Table of Contents  

Bahadur and Irani: Sports and exercise medicine – how to change the health of a nation

Introduction

As the world’s population grows, inactivity, obesity and associated ill health have become widespread, with far-reaching effects on patients, physicians and all aspects of health care. There are very few medical disorders that universally affect young and old, male and female, rich and poor, those living in urban and rural areas, developed, and developing countries and almost every human on the planet – yet obesity-related conditions have that unenviable attribute. Indeed, the 21st-century ailments associated with obesity and inactivity can be likened to the morbidity associated with smoking which led to 1.7 million hospital admissions in 2014 despite decreasing year on year in the UK since 1974.1 The current and potential consequences of inactivity/obesity have not emerged unnoticed – an ‘obesity time bomb’ was forecast as early as the 1970s.2 Despite this, year on year increases in the prevalence of obesity are seen in almost every country. These increases now affect younger populations and children, with almost 33% of US children currently classified as obese.3

The medical community has not ignored this problem; however, despite extensive resources and research, it has failed to prevent the progression of obesity and/or effectively treat those already affected by obesity. Pharmaceutical therapy to reduce weight, increase metabolic activity or reduce calorific storage has had limited success and the proven interventional therapies of gastric banding/bypass involve expensive, time-consuming surgery that may reduce weight in the short term but are increasingly associated with poor longer-term outcomes. The current medical approach has been to treat the ailments within each specialty as they emerge – blood pressure and ischaemic heart disease are treated by cardiologists, insulin deficiency by diabetologists, and osteoarthritis and degenerative joint disease by rheumatologists and orthopaedic surgeons.

General practitioners and family physicians are closest to taking a more unifying holistic role, being able to view the patient across specialties and observe how comorbidities are related within an individual and common to a local community. Epidemiologists and public health physicians could potentially have the greatest impact, yet education and publicity campaigns have shown limited benefit and mass intervention remains elusive or inappropriate and expensive.

Governments across the world have foreseen the additional expense, and overburdened, under-resourced health care systems have predominantly viewed the problem as one of ‘overeating’, and have pressurized food manufacturers to produce healthier options using the threat of taxes on high-fat, high-sugar products. But manufacturers are always one step ahead of changing perceptions of what foods are healthy. This is well illustrated by changes in shopping habits for ‘healthy food’ and food manufacturers’ response – ‘low-fat’ (but still high calorie) products were favoured in the 1990s, ‘low-carbohydrate’ (but still high calorie) foods in the 2000s and today ‘natural, non-artificial’ (but still high calorie) foods are in vogue. Money, profits and jobs are at risk, and food manufacturers will always want the population to eat ‘more’ while convincing them it is ‘less’. Of course, poor nutrition is simply one contributing factor; inactivity also plays a role, increasing the risk of overweight or obesity even in individuals whose diet is composed solely of ‘healthy’ food. Furthermore, the objective of increasing activity levels is not simply to reduce weight, as ill health is not due to obesity alone.

The ambition, as always in medicine, is to find interventions that have the greatest effect on overall health. Sports and exercise medicine (SEM) is ideally suited to tackle the many facets of this current and impending global problem in the most efficient, effective and cost-conscious way. SEM is unique in its potential to tackle this problem from every direction (inactivity, nutrition, exercise, obesity, education), treating those already affected and preventing future generations of children from becoming obese adults. Moreover, this impact is not confined to the overweight and inactive. Exercise can ameliorate apparently unrelated established disease and prevent illness. Indeed, looking at the evidence, regular exercise can improve cardiovascular disease,4 lower blood pressure,5 improve sugar control in diabetes,6 reduce mental illness7 and anxiety disorders,8 and even moderate the symptoms of late-stage cancers.9 It could even reduce mortality rates; mortality due to inactivity is estimated worldwide at 6% (5.3 million deaths in 2008).10 All populations and communities are potentially able to benefit from SEM involvement: the elderly in particular will benefit from the chronic disease-modifying effects, as will those high-risk populations in which exercise was previously contraindicated (e.g. patients with cardiovascular/metabolic disease).11 On a wider economic level, given the increasing monetary burden of health care in every nation, SEM interventions are ideal global therapies, being inexpensive and universally available. SEM physicians potentially hold the ‘cure’ that every nation is seeking to tackle, improve and prevent ill health in a cost-conscious world where economic issues cannot be ignored.

All of these aspects of SEM and how these benefits could be achieved will now be explored.

Sports and exercise medicine and improving the detrimental effects of inactivity

Inactivity is often regarded as a consequence of modern living and privilege, yet surprisingly this phenomenon is not confined to affluent populations or developed countries, as would be expected. The evidence would suggest that inactivity is an aspect of 21st-century life all over the world (Figure 1). In 2003, assessment of physical activity levels in 76 countries found an average of 17% of adults could be classed as inactive.13 More recently, 2010 surveillance by the WHO shows a continuing trend with 23% of the global adults classified as inactive.14 As expected, age was a factor in activity levels, with the elderly being less active; however, being female and having low income also showed a trend towards increased susceptibility to inactivity. Sedentary behaviour is prominent in inactive people, and this is not confined to older age groups. In a survey of European adolescents, 60% exceeded the recommended European guidelines for inactivity.15

FIGURE 1

National inactivity prevalence comparison in 2010 (WHO estimates).12

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Of course, surveys are often subjective, and objective evidence would be a better way of measuring true levels of inactivity. A US study monitored individuals wearing activity devices to determine exactly when they were active or sedentary.16 The analysis showed that, on average, participants were inactive for 7.7 hours or 54.9% of the waking day. Among those aged < 30 years, females were less active than males, but men aged > 60 years were less active than women of the same age.16 Although the findings were widely publicized, the trend continued, with inactivity levels increasing further in subsequent years.

As physicians try to find reasons for increasing inactivity, the modern working lifestyle has been implicated. Prolonged sitting, as required by most modern clerical/computer-based roles (few roles exclude the use of a computer), has regularly been postulated as an independent risk factor for all-cause mortality.17,18 This was reinforced by a 2016 meta-analysis of 1 005 791 patients which found that all-cause morbidity and mortality increased with increasing time spent sitting, and concluded that 60–75 minutes of moderate-intensity physical activity daily could eliminate this increased risk.19

This need for increased activity levels has been recognized, and various national and international attempts have been made to improve exercise levels (Table 1). In the USA, primary care family physicians were considered the most influential and time-efficient change promoters, while also reaching the greatest number of people. Recommendations were made in 2012 with an emphasis on family physicians selecting those patients at increased risk of cardiovascular morbidity.21 This is a step in the right direction; however, patients usually attend family physicians for ailments rather than preventative advice, and time to address these additional issues is limited. In the UK, primary care physicians have, on average, 7 minutes to assess, diagnose and treat each patient. Thus, it is only to be expected that discussion of exercise/nutritional advice by physician and patient will be limited during this time as it will of necessity be secondary to consideration of the patient’s primary presenting ailment.

TABLE 1

World Health Organization: global recommendations on physical activity for health 201020

Population Recommendation
Children aged 5–17 years 60 minutes of moderate-intensity to vigorous physical activity daily
Physical activity for > 60 minutes provides additional health benefits
Most of the daily physical activity should be aerobic
Adults aged 18–64 years 150 minutes of moderate-intensity aerobic physical activity throughout the week
Muscle-strengthening activities should be performed involving major muscle groups on ≥ 2 days per week
Adults aged ≥ 65 years 150 minutes of moderate-intensity aerobic physical activity throughout the week
Muscle-strengthening activities, involving major muscle groups, should be done on ≥ 2 days per week

Sports and exercise medicine physicians could fill this health-care gap in way that is focused on the individual patient, and in the community could achieve a greater impact than time-limited family physicians. The additional benefit for SEM would be an improvement in general health as well as treating inactivity-related morbidity. Indeed, individualized, targeted programmes have already been demonstrated to be effective in increasing activity22 and improving quality of life.23 Although every other specialty treats inactivity as a secondary concern, SEM physicians have this as their primary objective on a daily basis. As with other branches of medicine, the internet generation keeps up to date with the latest developments in medicine and will often ask about certain equipment, diets and exercises. Knowledge of the latest multifaceted approaches in exercise medicine, along with the usefulness of wearable technology (heart monitors, pulse-monitoring watches, etc.), is paramount. In an area where personal motivation is crucial (something that not unique to sports medicine, e.g. most patients admit to not taking any prescribed medication regularly), the knowledge base and experience of a SEM physician is key and better suited than any other medical specialist in improving activity levels and ultimately preventing inactivity-related morbidity. This personalized focused approach can lead to greater rewards beyond simply improving activity levels. The population is living longer and chronic diseases now need to be managed for a longer than in the past. This increasing elderly population has been highlighted as the main reason for increased health care expenditure in developed countries. This is having a daily effect in terms of resources, with one in four acute care hospitals in the UK declaring themselves unable to take more patients within the first 6 days of 2017.24

Sports and exercise medicine is potentially able to make a genuine impact on this critical situation at a fraction of the cost of building new hospitals. Exercise in middle age has been shown to directly reduce morbidity25 and decrease the risk of chronic conditions in the last 5 years of life (Table 2).26 Many politicians and health-care economists are blaming the success of medicine for allowing us to live longer. The associated apparent ‘disappointment’ is not aimed at longer life (which should be celebrated as a triumph of modern health care) but more a reflection of increasing cost of treating these chronic conditions for a longer period. SEM has the ability, knowledge and time to effect this change with short- and long-term benefits to the individual and society and, crucially, at a fraction of the cost of building new hospitals. Providing increased monetary resources may assist patients today, but this is an ever-increasing necessity and unsustainable in the current global economic situation. SEM physicians uniquely have the correct skills to reduce this predicted requirement within a relatively short time frame. Moreover, SEM interventions would improve overall health while potentially setting up better health for future generations. Again, these interventions are truly transferable to both the developed and developing world, requiring little technical equipment, and this one of the reasons why SEM should be considered by all health-care systems globally.

TABLE 2

Effects of exercise

Physiological system Beneficial effects
Metabolic Increased insulin sensitivity
Increased oxidative phosphorylation
Mitochondrial biogenesis
Vascular Increased angiogenesis
Increased aortic compliance and reduced aortic stiffness
Increased nitric oxide production
Decreased oxidative stress
Muscle Increased size and related fibre switching
Increased oxidative phosphorylation
Increased calcium handling
Cardiac Increased stroke volume and cardiac output
Increase in cardiac muscle mass
Improved calcium movement
Respiratory Increased vital capacity
Increased oxygen transport
Decreased blood viscosity
Decreased coagulation

Sports and exercise medicine and cardiovascular disease

Cardiovascular disease is the major cause of morbidity/mortality in the developed world and is set to overtake infectious disease as the leading cause in the developing world. A well-established robust reproducible association exists between regular exercise and a reduced incidence of cardiovascular disease (ischaemic heart disease, myocardial infarction) in both primary and secondary prevention.25 The precise pathological process is multifactorial; however, hypercholesterolaemia, hypertension, insulin deficiency, obesity, diet, smoking, alcohol and inactivity are all implicated. These factors were identified in the INTERHEART study, in which 15 152 individuals in 52 countries were analysed; significantly, these factors are important not only in developed, more affluent, populations but in men and women, and young and old, in all regions of the world.27

Sports and exercise medicine physicians can personalize their approach to target each of these factors, depending on which is dominant, while simultaneously achieving overall improvement in health. For example, those with abnormal lipid profiles would receive a predominantly aerobic training programme, as this has been proven to decrease very low-density lipoprotein and increase high-density lipoproteins.28,29 If hypertension is the prevailing pathology, resistance training with aerobics decreases systemic blood pressure by as much as 5–15 mmHg;30,31 increases are seen even when the causative factor is not known, as in ‘essential hypertension’. SEM is therefore well suited for tackling one of the greatest causes of morbidity and mortality at a fraction of the cost of current therapies. Thus, SEM should be considered by health services all over the world as a necessary addition to the variety of therapies available for engaging cardiovascular disease within their population.

Sports and exercise medicine and diabetes mellitus (management and prevention)

Diabetes mellitus has been described as a major epidemic in the developed world, and increasingly in the developing world. Many countries spend up to 15% of their disposable, non-infrastructure, health-care budget on treating the manifestations of this troublesome disabling condition. The effects on patients are many and far-reaching, including blindness, chronic infection, renal failure, poor healing of wounds and immobilizing neuropathy of varying degrees.

Sports and exercise medicine physicians are able to affect diabetes in a way that reaches beyond the purely direct glycaemic control that is the focus of diabetologists. SEM physicians can effect community-directed therapy, taking into account the environmental influences (a major factor in type 2 diabetes) that affect diet, sugar control during daily activities, control of patients’ symptoms to achieve an active life and weight management.

These SEM interventions are not based simply on weight reduction. Aerobic exercise has a direct modifying effect by increasing the amount of mitochondrial enzymes and increasing new vessel formation within muscle. This leads to improved glucose uptake32 and the creation of more glucose transport mechanisms, resulting in an increase in insulin sensitivity.33 Adding resistance training leads to reduced abdominal/visceral adipose tissue, increased muscle density and even greater insulin sensitivity.34 In patients with type 2 diabetes, exercise has been shown to improve control and reduce glycated haemoglobin (HbA1C) levels, which is a better indicator of long-term blood glucose control than values measured by daily blood testing, which can fluctuate.35 A combination of aerobic exercise and resistance training seems to show greater benefit than either method alone in those with type 2 diabetes.36 In those affected by type 1 diabetes, exercise tends to reduce insulin resistance and in such patients aerobic exercise has a greater beneficial effect than combined regimes.37 Optimal effects are achieved with longer-term programmes, which are ideally managed by a SEM physician who can offer individualized interventions and closely monitor their effects, rather than provided as an educational adjunct (often as a leaflet in a hospital waiting room). These programmes would not overwhelm existing resources and have been successfully compared to visiting the family physician twice a month (e.g. a SEM physician could monitor a programme comprising at least 150 minutes of aerobic exercise per week and resistance training twice per week38).

Preventing diabetes is the ultimate ambition as established end-organ damage is difficult to reverse. Evidence shows that SEM can help to prevent the development of type 2 diabetes. A systematic review of 10 prospective studies carried out in 200739 showed that the risk of developing type 2 diabetes was lower in those who exercised regularly (even walking) than in those with sedentary lifestyles. Even when the results were standardized for high body mass index (BMI), the association remained. More recent research has continued to confirm this finding, with the best results in those who combine regular aerobic (150 minutes per week) and resistance training.36 The input of a SEM physician into existing diabetes units would be a very useful asset to treat existing symptoms, improve glycaemic control, alleviate the comorbid risk factors and provide ongoing effects that last far beyond the consultation with their diabetologist.

Sports and exercise medicine and obesity

The development of obesity has a genetic component; however, the dominant processes involve individual and environmental factors. An excess calorific intake combined with lack of exercise will lead to this condition over a relatively short period of time, even in those not who are not genetically susceptible. However, it is now known that many factors contribute to this condition, and many are initiated very early in life.

Many factors are now being traced back even to gestation as mothers’ pre-pregnancy BMI and gestational BMI and, paradoxically, poor maternal nutrition are all associated with the baby’s body composition into childhood.40 Obesity in childhood is associated with obesity in adolescence, which is associated with severe obesity as an adult;41 therefore, the earlier we intervene with these patients, the less likely they are to progress to obesity.

Despite these earlier associations, most obese adults do not become obese until they are adults, and it still possible to intervene even at this stage in life to prevent the development of associated morbidity. Many women are susceptible to weight gain in pregnancy and at the time of menopause, and they subsequently find it difficult to reduce their weight without modifying their diet/exercise regime – yet few women are aware they may gain weight at these times. For adult men/women, insulin resistance and metabolic syndrome, social status (lower socioeconomic groups), low educational status, parental dietary influence, patterns of eating and nicotine withdrawal (on stopping smoking) can all result in excess weight gain and the development of obesity.

Although we can do little to alter our parental choices, the dominant factors common to all ages are an increasingly sedentary lifestyle with poor dietary choices and excess calorific intake. This perhaps reflects the dominant factors in rising obesity rates over the last 40 years (Figure 2). Research shows that the risk of developing obesity is very high, with 26% of normal-weight men and 14% of normal-weight women becoming overweight 4 years following their initial assessment. In a study in which participants were followed up for over 30 years, 50% of all participants developed clinical obesity.42

There are other associations that can serve as indicators for clinicians when evaluating risk for developing obesity. Time spent watching television is the single factor most closely related to developing obesity, which probably reflects a lifestyle associated with lack of exercise and dietary choices.43 Poor-quality sleep and particularly inadequate sleep has more recently been associated with significant weight gain.44

Diet is a major identifiable and modifiable direct causative factor in developing obesity – excess calories as well as the choice of food (e.g. sugar-loaded cereals) are associated with weight gain, whereas other foods (e.g. fruit, vegetables and nuts) are associated with weight loss.45

Unifying and modifying all of these factors is an area of expertise covered by SEM more than any other specialty, and input and direction from a knowledgeable SEM physician can potentially guide both patients and the people they interact with as regards weight management (e.g. exercise instructors, primary care primary prevention nurses, family physicians, hospital specialists and the highest-level tertiary care experts). Patients often get mixed messages and a unified voice from the SEM physician may prevent confusion.

FIGURE 2

Obesity levels since 1980.

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Indeed, a targeted multifactorial approach is better than simply thinking of obesity as excess calories that need to be removed through exercise. Exercise alone results in weight loss but appears more effective in reducing body fat.46 Exercise combined with diet results in slightly greater weight loss, and this combination seems to be the most effective. The SEM approach to obesity goes into more depth in ambitions for change; although some health-care providers will simply look at weight and BMI as the parameters of health, this is not the SEM approach. The patient is viewed in terms of treating medical morbidity, preventing the development of harmful disorders, as well as evaluating and considering other often-ignored facets such as improving mood and self-confidence. Viewing weight alone as the parameter for measuring obesity ignores the fact that exercise builds more muscle mass and this can offset weight loss.47 Similarly, the ambition for the SEM physician is to recognize that obesity goes beyond simply being overweight – it has associations with many comorbidities (e.g. insulin sensitivity, hypertension, increased mortality). Similarly, exercise goes beyond simply losing weight and an overall approach is best when confronted with an obese patient.

FIGURE 3

The annual cost of obesity in the UK.

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Obesity certainly is a phenomenon of modern life and is increasingly impacting on all specialties, including paediatrics and care of the elderly, with significant economic implications (Figure 3). Approaches thus far have not had a significant impact given the annual increases, and are gradually targeting younger age groups. An integrated approach is required, one that incorporates those strategies known to effectively reduce obesity and reduce the factors that cause obesity as well as the end-organ pathology; SEM physicians are able to provide this service and their involvement in regional and national strategies should be encouraged.

Sports and exercise medicine and osteoarthritis/degenerative joint disease

Osteoarthritis (OA) is a very common disorder thought to involve the combination of altered bone metabolism and physical remodelling influenced by applied force over the surfaces of opposing bones within joints. The duration and intensity of these repetitive forces seem to be significant factors given that the prevalence and severity of this condition increases with age. All chronic conditions are multifactorial, and OA is no exception; to attribute simply to bone surfaces clashing reflects of our lack of knowledge about the underlying process, and there are likely to be many undiscovered biochemical pathways involved. Although research continues to explore these mechanisms, recognizing those factors that we already know that contribute to the development of OA allows SEM physicians to establish a therapeutic approach aimed at preventing or modifying the detrimental effects of the condition.

Osteoarthritis is unique among diseases: although exercise improves almost all types of ill health (as shown throughout this review), it may actually contribute to causing OA given the extensive transmitted forces that are produced across joints when undertaking physical activity. Furthermore, exercise, and particularly intensive exercise (i.e. sport), involves repetitive forces applied to joint surfaces at high intensity in an adrenaline-fuelled environment that encourages participants to continue despite the pain response urging them to stop.

Sports and exercise medicine physicians therefore examine the effect of sport on joints, and are knowledgeable about how different sports load joints in different ways. Evaluating these activities can help answer the questions regarding whether or not these exercises may be responsible for causing OA. This is an area where SEM research has indirectly aided the understanding of non-exercise-related OA: sport is an exaggerated, concentrated (in terms of both load and frequency) version of daily activity, and a sportsperson’s joints may show damage equivalent to that incurred over decades through daily activities. Thus, understanding the link between sport and OA could benefit all patients with OA, and not only those engaging in sport (recreational and elite).

Examining how body weight is distributed across joints shows that different tissues carry different proportions of load, and this force can multiply depending on the sport being undertaken. All of the involved tissues (subchondral bone, ligaments, capsule, synovium, muscles) disperse body weight, and the articular cartilage covering the end-bone surface is central in distributing this force. Standing or sitting (static load) places different forces and stresses on these joint structures from walking, running and jumping (dynamic load).48 Dynamic loading exerts at least three times the force of static loading, and it is this significant extra applied force that causes the initial load-induced damage to joints. This increased load on bone articular surfaces is seen in both recreational and high-level sport and also the common activities of daily living. This is further evidence that non-sport-induced OA is due to increased repetitive load over time as a result normal daily activities rather than simply to time itself. Direct evidence of this specific loading was seen when using an instrumented knee implant that measured the stresses during routine activities of daily living.48 Peak forces were highest when descending stairs (364% of body weight), ascending stairs (316% of body weight), level walking (261% of body weight), one-legged stance (259% of body weight), knee bending (253% of body weight), standing up (246% of body weight), sitting down (225% of body weight) and two-legged stance (107% of body weight). These enormous forces could indicate that normal activities of daily life are to blame for OA associated with ageing. Individual factors are rarely to blame for its pathology and it is likely that the variety in muscle and joint units seen in sports practitioners equally applies to non-sporting joints. These include joint laxity, genetic predisposition, joint misalignment, previous trauma, sex and hypermobility, all of which can have an effect on joint disease,49 and this may explain why some people are more susceptible to developing OA.

The fact that normal activities may predispose people to OA over time suggests that exercise, and particularly sport (intensive exercise), may cause OA. To evaluate this further, a recent meta-analysis50 looked at the association between OA and different sports. Long-distance running and soccer were the most frequently researched because of high global participation, providing a large pool of subjects to review. Both of these sports involve repetitive force/loaded impact of the joints of the lower legs over long periods (soccer players run up to 7 miles during a typical 90-minute match) and are therefore ideal for evaluating the signs/effects of OA. The results showed that 15 (65.2%) studies demonstrated a significant link between sport and developing OA, with eight (34.8%) showing no link. All eight studies showing no link between sport and OA involved long-distance running. This suggests that long-distance running is not causative in developing OA.

This conclusion seems inconsistent in the case of a sport that involves repetitive forces on joints of the lower limbs on hard surfaces over a long duration of time. Part of SEM analysis encourages examining injury patterns, and injuries incurred as a result of running tend to affect tendons/muscles rather than knee menisci (as occurs in soccer). There is no evidence that running causes degradation of articular cartilage,51 which is a mark of OA. Furthermore, the applied dynamic forces during running are mainly longitudinal and not rotational, and runners try to reduce impact to cover maximal distance with minimal energy. Elite runners also develop those muscles surrounding the large joints and this protects the articular bone surfaces from direct contact.52 SEM attempts to apply findings from elite athletes to the general public who pursue sport recreationally rather than professionally. The available evidence also suggests that articular degradation does not occur in recreational distance runners.53 Magnetic resonance imaging carried out in recreational runners immediately after long-distance races (e.g. marathons), and which would be expected to cause maximal stress reactions and damage, has demonstrated no significant change.54 Distance running can therefore be safely recommended and is unlikely to cause OA. In fact, it may be that distance running is a method of reducing the risk of developing OA given that it prevents developing obesity, which is well known to predispose individuals to OA.55,56

In contrast to long-distance running, the evidence suggests that soccer can cause OA – all of the studies of soccer players found an increase in the incidence of OA,50 particularly in those with significant previous sporting or non-sporting injuries. The most common knee injury in soccer players is a tear of the anterior cruciate ligament (ACL). This link between previous injury and OA is well established57 in SEM circles and is something that many club physicians are very wary of in their players.

This association between OA and previous injury was confirmed more recently in a study of 124 consecutive patients requiring knee replacement for unilateral OA.58 A significant number of these patients were found to have suffered a sports-related injury in that leg in the past. This is not the only evidence demonstrating that sports-related trauma can have significant implications for the athlete not just at the time of injury, but many years later, perhaps even causing disability. This propensity to OA exists even when damaged tissue is repaired, for example ACL tears. The evidence shows that compression loads between the articular cartilages of the affected knee remain greater than they were before the injury occurred.59 This multiplication of force may be the factor that accelerates the formation of OA in that knee. Another equally plausible explanation for OA in soccer players comes from looking at the sport itself – most techniques involve rotational forces that are not present in long-distance running. It may be that the rotation of applied force adds greater pressure to the menisci. Long-distance running involves more linear movement that is better distributed throughout the joint.

Sports and exercise medicine physicians often face the dilemmas that patients and their clubs want a solution that allows the player to return to the sport while preventing further damage. Often these patients have been advised by other specialties that no such treatment exists. From the above evidence, it would indeed seem that soccer players are destined to develop OA. However, there is evidence that learning a landing technique incorporating hip/knee flexion reduces joint loads,60 which thereby reducing the potential for the development OA. Studying the biomechanics of soccer and evaluating an individual’s training and match performance can allow a SEM physician to protect players from injury without curtailing their careers. On a global level, soccer is the most played recreational sport in the world. In any country, rich or poor, there are children playing for hours in the school playgrounds and on the streets; given the enormous amount of time these children spend playing, this may be an area of potential involvement for SEM physicians to ensure that children and young people are not at risk of developing an associated pathology later in life.

Upper limb OA, caused through sporting activity and exercise, has not been researched as frequently as lower limb injuries; knee injuries are much more common and easier to evaluate/examine, and sports involving mainly the upper limbs are less popular and do not attract the same interest and funding. However, in terms of disability and overall effect on activities of daily living, OA is a common disorder affecting the joints of the shoulder, leading to disability and degeneration.61 Among those participating weight-bearing sport, women have been shown to have a higher risk than men of developing shoulder OA. This applies to those either with a previous injury or in those who are injury free.

Women generally seem to be more susceptible to developing OA as a result of sport, and yet very little research into the reasons for this has been carried out; there have been calls for more in-depth investigation in this population group, such as in a recent meta-analysis62 of sporting injuries. Possible explanations could be that specific hormonal variations are known to affect the laxity/elasticity of ligaments within joints. OA affects post-menopausal women to a much greater extent than men of the equivalent age and pseudomenopausal endocrine states can occur in elite athletes, in whom menstrual cycles diminish as a result of either body weight fluctuations or extreme training schedules aiming for advantages in competition. Furthermore, there is strong historical evidence that women are more prone to hypermobility syndrome in varying degrees (this often remains undiagnosed until these patients are reviewed by a SEM physician), which is thought to be a factor predisposing to OA.63

Despite the strong link between certain sports and OA, it is important to be aware of the many positive benefits that exercise brings, including prognostically significant improvements in longevity and the absence of debilitating musculoskeletal symptoms. It should also be borne in mind that trauma, obesity and military service have all been associated with a higher risk of developing OA than any of the sports in the above analysis.64 Indeed, it could be argued that most of the evidence showing a link between sport and OA could be due to small injuries sustained to the joint because of the high sporting level of study subjects. This has been described as ‘the confounding effect of injury’ and highlights the difficulty in attributing the development of OA to sport or sport-induced trauma.65 For the SEM physician, trauma is accepted as a possible causative factor in developing OA, and injury prevention is therefore regarded as being of paramount importance in both recreational sportspersons as well as elite athletes. Some have suggested that rule changes should be introduced in those sports that are particularly prone to inducing trauma in order to minimize injury. Although this would be ideal, such significant major changes will require time and agreement between national and international bodies. An alternative is to educate athletes to be aware of the future risks of OA to minimize impact/trauma by the use of protective gear, such as taping and bracing equipment. In addition, it is recommended that such advice should be available to the general public, and particularly young people, and those susceptible should be targeted for prevention of future OA, highlighting the cost benefits of prevention over subsequent treatment.66

Sports and exercise medicine and mortality

Prolonging life and improving quality of life is the ambition in treating all disease. Exercise (recreational and elite) has been shown to reduce mortality from all causes as well as indirectly in terms of improving chronic diseases.67 The level of exercise to achieve this reduction was previously thought to be extensive and time-consuming; however, more recent evidence suggests that small amounts of daily exercise can also prolong life expectancy.68 Although exercise at a younger age will have a greater effect, there is evidence that taking up exercise at an older age also prolongs life by reducing all-cause mortality.69 Indeed, a study of 30 640 Danish adults of all ages (men and women aged 20–93 years) demonstrated decreased mortality secondary to increased leisure-time physical activity, with even better results among those participating in sports or cycling to work.70

The exercise levels required to achieve such benefits were previously thought to be excessive and time-consuming, yet this is not the case. A prospective study compared walking with vigorous exercise in 72 488 women over 8 years.71 Brisk walking (3 hours per week) was associated with a 30–40% risk reduction in coronary events, and this was similar to that achieved in those who undertook vigorous physical exercise.71 In 2011, another prospective study of 416 175 people from Taiwan correlated the minimum activity levels with reduced mortality, and found that 15 minutes per day or 90 minutes per week of moderate-intensity exercise was effective at reducing all-cause mortality by 14%, or prolonged life by 3 years.68 Increasing daily activity by 15 minutes per day reduced survival from all-cause mortality by 4% and all-cause cancer mortality by 1%.

Most people would want to participate in exercise given these positive benefits; however, SEM physicians are able to extract the reasons preventing participation. Much confusion exists about the different programmes, activity levels and types of exercise to undertake. An individualized approach is best; however, most medical practitioners have little time to assess a patient’s lifestyle and adapt a programme to achieve the desired health improvements. SEM physicians are capable of fulfilling this role in a time-efficient manner on an individual basis.

This is especially important in those patients who are coming back to physical exercise for health benefits and have a background of lower physical activity through their lifestyle (e.g. work, parenthood, dislike of gyms). A starting point is advising that all energy-expending activities are increased (e.g. using stairs at work instead of the lift, walking the last public transport stop to work, exercises at home). This approach means that any enjoyable activity can be adopted to improve health and new activities can be added as fitness and motivation levels improve. Indeed, there is evidence that the type of exercise is irrelevant and energy expenditure is the prime factor in how exercise reduces all-cause mortality.69,72

Although increased life expectancy is admirable, the ideal ambition is to have a good quality of life during these extra years. The expense of providing personal care for those living longer but with a poorer quality of life is something that is increasingly being identified as a reason why health-care systems all over the world are overburdened. SEM has the advantage here in being able to influence all aspects of health (mobility, respiration, cardiovascular reserve, mood); thus, incorporating SEM physicians into patient care in later life could result in dramatic improvements in quality of life where other methods have failed, and this should be seriously considered by all health-care providers.

Sports and exercise medicine and other illnesses

Exercise is rarely associated with improvement in mood and psychological illness, yet there is increasing evidence that exercise improves low mood and also reduces stress and anxiety.73 Furthermore, this effect is dose dependent, with higher levels of exercise associated with even greater improvement.74 In addition, there is now evidence that moderate-intensity exercise for only 30 minutes results in improved concentration and cognition.75

Cancer is an illness that many dread, even though current statistics suggest that one in two people in the UK will be diagnosed with this disease at some point in their life.76 A recent 2016 meta-analysis suggested that exercise can help prevent breast, prostate, endometrial, pancreatic and colorectal cancer.77 However, the benefits of exercise are not confined to prevention: exercise can also alleviate many of the effects that are associated with cancer treatment. The positive effects do not stop here – exercise can also alleviate those symptoms that remain even though treatment has finished (e.g. fatigue). This is valuable advice for those clinicians faced with patients who suffer such symptoms and who are usually not amenable to pharmaceutical therapy.

Sports and exercise medicine physicians have the advantage of being able to see the benefits of exercise beyond simply treating the medical ailment. This approach can therefore impact those areas where many patients feel reluctant to seek help (e.g. low mood) and many physicians are unaware of the link between exercise and improvement (e.g. cancer, cognitive decline). SEM physicians should therefore routinely be involved in these life-changing conditions as the benefits could multiply the effect of conventional therapy.

Have we convinced you to become a sports and exercise medicine physician?

Sports and exercise medicine is a relatively recent post-graduate specialization in medicine that has evolved from being a part-time additional interest to a fully fledged medical training programme, resulting in specialist status. Interest has grown recently because high-profile physicians are linked to famous sports teams. Governments are now recognizing the potential for exercise as a cost-effective method for preventing long-term illness and have incorporated formal SEM post-graduate training programmes approved by their national universities. Investment into training doctors in this field is now standard in many countries.

Sports and exercise medicine involves in-depth study of a number of other disciplines (e.g. cardiology, respiratory, rheumatology). The knowledge base is musculoskeletal medicine and all of the injuries and management that may occur within the musculoskeletal system. Physiology and understanding exercise and nutrition is, again, studied in depth as this has a direct influence on all aspects of recreational sports participants as well as elite athletes.

Even at the elite level, which is the ambition for most SEM physicians, it must be taken into consideration that these patients are not exempt from the diseases that affect the rest of society (e.g. diabetes, asthma, psoriasis). Thus, SEM physicians tend to be good generalists and often have a background of specialist medicine, general practice or surgery, reflecting a high level of previous experience. Unlike doctors in many other specialties, SEM physicians are expected to be proficient in paediatrics and adolescent medicine; many UK schools are now employing SEM physicians to care for their school teams and create physical education programmes.

Sports and exercise medicine physicians typically work with professional teams during their training. This often means working weekends and evenings and lots of national and international travel. SEM physicians are often adopted as a team member and on first-name terms with all the players and managerial staff. This loyalty makes the SEM physician unique and closer to the team than in many hospital-based specialties. SEM physicians often feel privileged to work with players on improving results as much as the coaches. The drawback is that, being permanently on call, you may be contacted at any time for advice.

Sports and exercise medicine physicians also play an important role in the military in almost every country given the physical nature of the armed services. In large cities, SEM physicians are often employed in the private sector, as both amateurs and professionals prefer to see a sports physician rather than their own doctor. This work can be very rewarding financially; however, the working hours tend to involve day, evening and weekend shifts, and working ‘unsociable’ hours is certainly something prevalent in a career in SEM.

In terms of employment security, the outlook remains promising. The increasing prevalence of obesity means that there will be much demand for those involved in managing this condition and its many effects. Interest in fitness has increased and SEM physicians are the most specialized medical doctors that are best suited to address the needs of these patients.

The route into SEM depends on the degree of involvement that you foresee:

  1. a basic medical degree is required (taking 5 or 6 years);

  2. apprentice/house years (2 years covering basic medicine, basic surgery and other specialties at a junior level);

  3. specialty training (4–6 years depending on route taken);

    • SEM training programme – a post-graduate medical qualification is required (membership of the Royal Colleges in the UK). This will mean either completing a core medical/surgical training programme for 2 or 3 years and gaining the MRCP/MRCS or engaging in a general practice training programme and gaining the MRCGP. The SEM programme then lasts for 4 years and enables you to register in the UK on the specialist register.

    • general practice/family physician – completing a diploma in SEM will give you the knowledge to be able to work in SEM. This is not mandatory, however many teams will want evidence of expertise in SEM.

    • rheumatology/orthopaedics/cardiology/respiratory/other – any other specialty can work in SEM either with/without a diploma in SEM. Of course, teams will want evidence of aptitude in SEM.

Most SEM doctors have a very high level of job satisfaction, high earning capability and consider themselves privileged as a result of their work with high-level athletes.

References

1. 

Health and Social Care information Centre. Statistics on Smoking: England, 2016. Leeds: Health and Social Care information Centre; 2016.

2. 

Galka M. How the world got fat: a visualiation of global obesity over 40 years. The Guardian, 3 Jan 2017.

3. 

Ogden CL, Carroll MD, Kit BK, Flegal KM. Prevalence of obesity and trends in body mass index among US children and adolescents, 1999–2010. JAMA 2012; 307:483–90. https://doi.org/10.1001/jama.2012.40

4. 

Bernhard S, Dynic M, Presser A, Halle M. [Prevention of cardiovascular diseases through sport and physical activity: a question of intensity?] Hers 2015; 40:361–8. http://dx.doi.org/10.1007/s00059-015-4216-4

5. 

Rossi AM, Moulled G, Lavoie KL, Gourd-Provençal G, Bacon SL. The evolution of a Canadian Hypertension Education Program recommendation: the impact of resistance training on resting blood pressure in adults as an example. Can J Cardiol 2013; 29:622–7. http://dx.doi.org/10.1016/j.cjca.2013.02.010

6. 

Myers VH, McKay MA, Brashear MM, et al. Exercise training and quality of life in individuals with type 2 diabetes: a randomized controlled trial. Diabetes Care 2013; 36:1884–90. https://doi.org/10.2337/dc12-1153

7. 

Zschucke E, Gaudlitz K, Ströhle A. Exercise and physical activity in mental disorders: clinical and experimental evidence. J Prev Med Public Health 2013; 46(Suppl. 1):12–21. http://dx.doi.org/10.3961/jpmph.2013.46.S.S12

8. 

Jayakody K, Gunadasa S, Hosker C. Exercise for anxiety disorders: systematic review. Br J Sports Med 2013; 48:187–96. https://doi.org/10.1136/bjsports-2012-091287

9. 

Cheville AL, Kollasch J, Vandenberg J, et al. A home-based exercise program to improve function, fatigue, and sleep quality in patients with stage IV lung and colorectal cancer: a randomized controlled trial. J Pain Symptom Manage 2012; 45:811–21. https://doi.org/10.1016/j.jpainsymman.2012.05.006

10. 

Lee IM, Shiroma EJ, Lobelo F, Puska P, Blair SN, Katzmarzyk PT, Lancet Physical Activity Series Working Group. Effect of physical inactivity on major non-communicable diseases worldwide: an analysis of burden of disease and life expectancy. Lancet 2012; 380:219–29. http://dx.doi.org/10.1016/S0140-6736(12)61031-9

11. 

Shiraev T, Barclay G. Evidence based exercise – clinical benefits of high intensity interval training. Aust Fam Physician 2012; 41:960–2.

12. 

World Health Organisation. Prevalence of insufficient physical activity among adults. URL: http://apps.who.int/gho/data/node.main.A893?lang=en (accessed 24 February 2017).

13. 

Dumith SC, Hallal PC, Reis RS, Kohl HW 3rd. Worldwide prevalence of physical inactivity and its association with human development index in 76 countries. Prev Med 2011; 53:24–8. https://doi.org/10.1016/j.ypmed.2011.02.017

14. 

World Health Organisation. Physical Activity: Fact sheet. 2017. URL: www.who.int/mediacentre/factsheets/fs385/en/ (accessed 24 February 2017).

15. 

Rey-López JP, Vicente-Rodriguez G, Ortega FB, et al. Sedentary patterns and media availability in European adolescents: The HELENA study. Prev Med 2010; 51:50–5. https://doi.org/10.1016/j.ypmed.2010.03.013

16. 

Matthews CE, Chen KY, Freedson PS, et al. Amount of time spent in sedentary behaviors in the United States, 2003–2004. Am J Epidemiol 2008; 167:875–81. http://dx.doi.org/10.1093/aje/kwm390

17. 

van der Ploeg HP, Chey T, Korda RJ, Banks E, Bauman A. Sitting time and all-cause mortality risk in 222 497 Australian adults. Arch Intern Med 2012; 172:494–500. https://doi.org/10.1001/archinternmed.2011.2174

18. 

Biswas A, Oh PI, Faulkner GE, et al. Sedentary time and its association with risk for disease incidence, mortality, and hospitalization in adults: a systematic review and meta-analysis. Ann Intern Med 2015; 162:123–32. http://dx.doi.org/10.7326/M14-1651

19. 

Ekelund U, Steene-Johannessen J, Brown WJ, et al. Does physical activity attenuate, or even eliminate, the detrimental association of sitting time with mortality? A harmonised meta-analysis of data from more than 1 million men and women. Lancet 2016; 388:1302–10. https://doi.org/10.1016/S0140-6736(16)30370-1

20. 

World Health Organisation. Global Recommendations On Physical Activity For Health. Geneva, Switzerland: World Health Organisation; 2010.

21. 

Grandes G, Sanchez A, Sanchez-Pinilla RO, et al. Effectiveness of physical activity advice and prescription by physicians in routine primary care: a cluster randomized trial. Arch Intern Med 2009; 169:694–701. https://doi.org/10.1001/archinternmed.2009.23

22. 

Pavey TG, Taylor AH, Fox KR, et al. Effect of exercise referral schemes in primary care on physical activity and improving health outcomes: systematic review and meta-analysis. BMJ 2011; 343:d6462. http://dx.doi.org/10.1136/bmj.d6462

23. 

Lawton BA, Rose SB, Elley CR, Dowell AC, Fenton A, Moyes SA. Exercise on prescription for women aged 40–74 recruited through primary care: two year randomised controlled trial. Br J Sports Med 2009; 43:120–3.

24. 

Donnelly L. A&E crisis deepens with 65 hospital trusts issuing emergency alerts. The Telegraph, 13 Jan 2017.

25. 

Kodama S, Saito K, Tanaka S, et al. Cardiorespiratory fitness as a quantitative predictor of all-cause mortality and cardiovascular events in healthy men and women: a meta-analysis. JAMA 2009; 301:2024–35. http://dx.doi.org/10.1001/jama.2009.681

26. 

Willis BL, Gao A, Leonard D, Defina LF, Berry JD. Midlife fitness and the development of chronic conditions in later life. Arch Intern Med 2012; 172:1333–40. http://dx.doi.org/10.1001/archinternmed.2012.3400

27. 

Yusuf S, Hawken S, Ounpuu S, et al. Effect of potentially modifiable risk factors associated with myocardial infarction in 52 countries (the INTERHEART study): case–control study. Lancet 2004; 364:937–52. https://doi.org/10.1016/S0140-6736(04)17018-9

28. 

Wood PD, Haskell W, Klein H, Lewis S, Stern MP, Farquhar JW. The distribution of plasma lipoproteins in middle-aged male runners. Metab Clin Exp 1976; 25:1249–57. https://doi.org/10.1016/S0026-0495(76)80008-X

29. 

Williams PT, Krauss RM, Wood PD, Lindgren FT, Giotas C, Vranizan KM. Lipoprotein subfractions of runners and sedentary men. Metab Clin Exp 1986; 35:45–52. https://doi.org/10.1016/0026-0495(86)90094-6

30. 

Strasser B, Siebert U, Schobersberger W. Resistance training in the treatment of the metabolic syndrome: a systematic review and meta-analysis of the effect of resistance training on metabolic clustering in patients with abnormal glucose metabolism. Sports Med 2010; 40:397–415. https://doi.org/10.2165/11531380-000000000-00000

31. 

Stewart KJ, Bacher AC, Turner KL, et al. Effect of exercise on blood pressure in older persons: a randomized controlled trial. Arch Intern Med 2005; 165:756–62. https://doi.org/10.1001/archinte.165.7.756

32. 

Jensen TE, Richter EA. Regulation of glucose and glycogen metabolism during and after exercise. J Physiol 2012; 590:1069–76. http://dx.doi.org/10.1113/jphysiol.2011.224972

33. 

McAuley KA, Williams SM, Mann JI, et al. Intensive lifestyle changes are necessary to improve insulin sensitivity: a randomized controlled trial. Diabetes Care 2002; 25:445–52. https://doi.org/10.2337/diacare.25.3.445

34. 

Cuff DJ, Meneilly GS, Martin A, Ignaszewski A, Tildesley HD, Frohlich JJ. Effective exercise modality to reduce insulin resistance in women with type 2 diabetes. Diabetes Care 2003; 26:2977–82. https://doi.org/10.2337/diacare.26.11.2977

35. 

Umpierre D, Ribeiro PA, Kramer CK, et al. Physical activity advice only or structured exercise training and association with HbA1c levels in type 2 diabetes: a systematic review and meta-analysis. JAMA 2011; 305:1790–9. https://doi.org/10.1001/jama.2011.576

36. 

Church TS, Blair SN, Cocreham S, et al. Effects of aerobic and resistance training on hemoglobin A1c levels in patients with type 2 diabetes: a randomized controlled trial. JAMA 2010; 304:2253–62. https://doi.org/10.1001/jama.2010.1710

37. 

Murillo S, Brugnara L, Novials A. One year follow-up in a group of half-marathon runners with type-1 diabetes treated with insulin analogues. J Sports Med Phys Fitness 2010; 50:506–10.

38. 

American Diabetes Association. Standards of medical care in diabetes – 2013. Diabetes Care 2013; 36(Suppl. 1):11–66. https://doi.org/10.2337/dc13-S011

39. 

Jeon CY, Lokken RP, Hu FB, van Dam RM. Physical activity of moderate intensity and risk of type 2 diabetes: a systematic review. Diabetes Care 2007; 30:744–52. https://doi.org/10.2337/dc06-1842

40. 

Oken E, Taveras EM, Kleinman KP, Rich-Edwards JW, Gillman MW. Gestational weight gain and child adiposity at age 3 years. Am J Obstet Gynecol 2007; 196:322.e1–8. https://doi.org/10.1016/j.ajog.2006.11.027

41. 

The NS, Suchindran C, North KE, Popkin BM, Gordon-Larsen P. Association of adolescent obesity with risk of severe obesity in adulthood. JAMA 2010; 304:2042–7.

42. 

Vasan RS, Pencina MJ, Cobain M, Freiberg MS, D’Agostino RB. Estimated risks for developing obesity in the Framingham Heart Study. Ann Intern Med 2005; 143:473–80. https://doi.org/10.7326/0003-4819-143-7-200510040-00005

43. 

Hu FB, Li TY, Colditz GA, Willett WC, Manson JE. Television watching and other sedentary behaviors in relation to risk of obesity and type 2 diabetes mellitus in women. JAMA 2003; 289:1785–91. https://doi.org/10.1001/jama.289.14.1785

44. 

Cappuccio FP, Taggart FM, Kandala NB, et al. Meta-analysis of short sleep duration and obesity in children and adults. Sleep 2008; 31:619–26.

45. 

Mozaffarian D, Hao T, Rimm EB, Willett WC, Hu FB. Changes in diet and lifestyle and long-term weight gain in women and men. N Engl J Med 2011; 364:2392–404. http://dx.doi.org/10.1056/NEJMoa1014296

46. 

Irwin ML, Yasui Y, Ulrich CM, et al. Effect of exercise on total and intra-abdominal body fat in postmenopausal women: a randomized controlled trial. JAMA 2003; 289:323–30. https://doi.org/10.1001/jama.289.3.323

47. 

Chomentowski P, Dubé JJ, Amati F, et al. Moderate exercise attenuates the loss of skeletal muscle mass that occurs with intentional caloric restriction-induced weight loss in older, overweight to obese adults. J Gerontol A Biol Sci Med Sci 2009; 64:575–80. https://doi.org/10.1093/gerona/glp007

48. 

Kutzner I, Heinlein B, Graichen F, et al. Loading of the knee joint during activities of daily living measured in vivo in five subjects. J Biomech 2010; 43:2164–73. http://dx.doi.org/10.1016/j.jbiomech.2010.03.046

49. 

Hart LE, Haaland DA, Baribeau DA, Mukovozov IM, Sabljic TF. The relationship between exercise and osteoarthritis in the elderly. Clin J Sport Med 2008; 18:508–21. http://dx.doi.org/10.1097/JSM.0b013e3181865ed4

50. 

Bahadur S. Does Sport and Exercise Cause Osteoarthritis? Royal Society of Medicine, Sports Medicine Conference, London, UK, January 2016.

51. 

Willick SE, Hansen PA. Running and osteoarthritis. Clin Sports Med 2010; 29:417–28. https://doi.org/10.1016/j.csm.2010.03.006

52. 

Hohmann E, Wörtler K, Imhoff A. [Osteoarthritis from long-distance running?] Sportverletz Sportschaden 2005; 19:89–93. http://dx.doi.org/10.1055/s-2005-858043

53. 

Boocock M, McNair P, Cicuttini F, Stuart A, Sinclair T. The short-term effects of running on the deformation of knee articular cartilage and its relationship to biomechanical loads at the knee. Osteoarthr Cartil 2009; 17:883–90. http://dx.doi.org/10.1016/j.joca.2008.12.010

54. 

Hohmann E, Wörtler K, Imhoff AB. MR imaging of the hip and knee before and after marathon running. Am J Sports Med 2004; 32:55–9. https://doi.org/10.1177/0363546503258904

55. 

Williams PT. Effects of running and walking on osteoarthritis and hip replacement risk. Med Sci Sports Exerc 2013; 45:1292–7. http://dx.doi.org/10.1249/MSS.0b013e3182885f26

56. 

Cymet TC, Sinkov V. Does long-distance running cause osteoarthritis? J Am Osteopath Assoc 2006; 106:342–5.

57. 

Conaghan PG. Update on osteoarthritis part 1: current concepts and the relation to exercise. Br J Sports Med 2002; 36:330–3. https://doi.org/10.1136/bjsm.36.5.330

58. 

Tjoumakaris FP, Van Kleunen J, Weidner Z, Huffman GR. Knee sports injury is associated with an increased prevalence of unilateral knee replacement: a case-controlled study. J Knee Surg 2012; 25:403–6. http://dx.doi.org/10.1055/s-0032-1313753

59. 

Markolf K, Jackson S, Foster B, McAllister DR. ACL forces and knee kinematics produced by axial tibial compression during a passive flexion–extension cycle. J Orthop Res 2014; 32:89–95. https://doi.org/10.1002/jor.22476

60. 

Tsai LC, Powers CM. Increased hip and knee flexion during landing decreases tibiofemoral compressive forces in women who have undergone anterior cruciate ligament reconstruction. Am J Sports Med 2013; 41:423–9. http://dx.doi.org/10.1177/0363546512471184

61. 

Killian ML, Cavinatto L, Galatz LM, Thomopoulos S. Recent advances in shoulder research. Arthritis Res Ther 2012; 14:214. http://dx.doi.org/10.1186/ar3846

62. 

Driban JB, Hootman JM, Sitler MR, Harris KP, Cattano NM. Association between sports participation and the risk of knee osteoarthritis: a systematic review. Proceedings of the Annual Scientific Meeting of the American College of Rheumatology and Association of Rheumatology Health Professionals, Chicago, IL, USA, 2011.

63. 

Boyan BD, Hart DA, Enoka RM, et al. Hormonal modulation of connective tissue homeostasis and sex differences in risk for osteoarthritis of the knee. Biol Sex Differ 2013; 4:3. http://dx.doi.org/10.1186/2042-6410-4-3

64. 

Antony B, Jones G, Jin X, Ding C. Do early life factors affect the development of knee osteoarthritis in later life: a narrative review. Arthritis Res Ther 2016; 18:202. https://doi.org/10.1186/s13075-016-1104-0

65. 

Bennell K, Hunter DJ, Vicenzino B. Long-term effects of sport: preventing and managing OA in the athlete. Nat Rev Rheumatol 2012; 8:747–52. http://dx.doi.org/10.1038/nrrheum.2012.119

66. 

Emery CA, Roy TO, Whittaker JL, Nettel-Aguirre A, van Mechelen W. Neuromuscular training injury prevention strategies in youth sport: a systematic review and meta-analysis. Br J Sports Med 2015; 49:865–70. https://doi.org/10.1136/bjsports-2015-094639

67. 

Franco OH, de Laet C, Peeters A, Jonker J, Mackenbach J, Nusselder W. Effects of physical activity on life expectancy with cardiovascular disease. Arch Intern Med 2005; 165:2355–60. https://doi.org/10.1001/archinte.165.20.2355

68. 

Wen CP, Wai JP, Tsai MK, et al. Minimum amount of physical activity for reduced mortality and extended life expectancy: a prospective cohort study. Lancet 2011; 378:1244–53. http://dx.doi.org/10.1016/S0140-6736(11)60749-6

69. 

Manini TM, Everhart JE, Patel KV, et al. Daily activity energy expenditure and mortality among older adults. JAMA 2006; 296:171–9. https://doi.org/10.1001/jama.296.2.171

70. 

Andersen LB, Schnohr P, Schroll M, Hein HO. All-cause mortality associated with physical activity during leisure time, work, sports, and cycling to work. Arch Intern Med 2000; 160:1621–8. https://doi.org/10.1001/archinte.160.11.1621

71. 

Manson JE, Hu FB, Rich-Edwards JW, et al. A prospective study of walking as compared with vigorous exercise in the prevention of coronary heart disease in women. N Engl J Med 1999; 341:650–8. http://dx.doi.org/10.1056/NEJM199908263410904

72. 

Leitzmann MF, Park Y, Blair A, et al. Physical activity recommendations and decreased risk of mortality. Arch Intern Med 2007; 167:2453–60. https://doi.org/10.1001/archinte.167.22.2453

73. 

Sharma S, Madaan V, Petty FD. Exercise for mental health. Prim Care Companion J Clin Psychiatry 2006; 8:106. https://doi.org/10.4088/PCC.v08n0208a

74. 

Martin CK, Church TS, Thompson AM, Earnest CP, Blair SN. Exercise dose and quality of life: a randomized controlled trial. Arch Intern Med 2009; 169:269–78. http://dx.doi.org/10.1001/archinternmed.2008.545

75. 

Loprinzi PD, Kane CJ. Exercise and cognitive function: a randomized controlled trial examining acute exercise and free-living physical activity and sedentary effects. Mayo Clin Proc 2015; 90:450–60. http://dx.doi.org/10.1016/j.mayocp.2014.12.023

76. 

Cancer Research UK. One in two people in the UK will get cancer, experts forecast. ScienceDaily. ScienceDaily, 3 Feb 2015.

77. 

Kyu HH, Bachman VF, Alexander LT, et al. Physical activity and risk of breast cancer, colon cancer, diabetes, ischemic heart disease, and ischemic stroke events: systematic review and dose–response meta-analysis for the Global Burden of Disease Study 2013. BMJ 2016; 354:i3857. https://doi.org/10.1136/bmj.i3857


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