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Sports medicine

Physical activity: the cheapest polypill on the market

Donald Kuah, BRANDI COLE
OPEN ACCESS

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Abstract

There is now strong evidence that regular physical activity reduces the risk of a range of health problems. Assessing patients for physical activity and encouraging regular participation should be part of routine care.

Physical inactivity is a major modifiable cause of disease burden worldwide and the fourth leading risk factor for global mortality behind tobacco smoking, hypertension and elevated blood glucose, yet 60% of Australians do not meet the recommended guidelines for physical activity.1,2 Traditionally, medical teaching has emphasised obesity as a risk factor for death and disease, with surrogate markers for obesity (BMI and waist circumference) easy to obtain in a physical examination. Weight loss via calorie restriction, exercise or a combination of both remains the cornerstone of therapy for overweight and obese individuals. However, emerging evidence suggests that a shift in focus to promoting increased cardiorespiratory fitness by encouraging regular participation in physical activity – rather than attempted weight loss – may actually decrease the burden of disease far more significantly.1,2

Fitness versus fatness

The association of cardiorespiratory fitness and weight status with mortality from all causes has been studied using meta-­analytical methodology.3 In this study, 92,986 participants were divided into three weight groups: normal weight (BMI 18 to 25 kg/m2), overweight (BMI 25 to 30 kg/m2) and obese (BMI >30 kg/m2); these groups were then split into ‘fit’ and ‘unfit’ groups based on cardio­respiratory fitness during VO2 testing, which measures maximum oxygen consumption and muscle efficiency. The fit group was defined as participants with the top 80% of fitness scores in each weight category and the unfit group was defined as those with the bottom 20% of fitness scores. The groups were followed over time and the risk of death in each group was compared to the normal-weight fit group. The overweight and obese fit groups had a small, insignificantly increased risk of death compared to the normal-weight fit group (1.13 and 1.21 more times likely to die, respectively). However, all three unfit groups had alarmingly increased risk. The unfit normal-weight group were 2.42 times more likely to die than their fit counterparts, and the increased risk was 2.14 times in the unfit overweight group and 2.46 times in the unfit obese group.

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This study highlights the importance of physical activity, and shows that it is better to be fit and fat than to be normal weight and unfit.

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Benefits of regular exercise

Regular participation in physical activity increases cardiorespiratory fitness and is known to reduce the risk of health problems (Figure 1). These include cardiovascular disease and stroke, type 2 diabetes, cancer, depression, osteoarthritis and osteoporosis.

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Exercise and cardiovascular disease

Exercising regularly decreases the risk of coronary disease, cardiac events, and cardiovascular death for both primary and secondary prevention. Physical inactivity is associated with almost double the risk of coronary heart disease and results in poorer prognosis in survivors of myocardial infarction compared with their more active counterparts.4 Regular exercisers are 25% less likely to die after a myocardial infarction than sedentary people.4 Exercise reduces cardio­vascular risk partly by improving lipid profiles, predominantly by a reduction in serum triglycerides and an increase in serum high-density lipoprotein (HDL) cholesterol, along with a less well-defined reduction in low-­density lipoprotein (LDL) cholesterol.4 Regular exercise can also lower blood pressure by 5 to 15 mmHg within four weeks in people with primary hypertension.4 Exercise improves functional capacity in people with existing heart disease and can reduce angina symptoms, lessen breathlessness associated with heart ­failure and reduce claudication associated with peripheral vascular disease.

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Dr Kuah is Sports and Exercise Physician at Sydney Sports Medicine Centre, Sydney. He is also Chairperson of the NRL Medical and Player Safety Advisory Group. Dr Cole is a Sports and Exercise Medicine Registrar at Sydney Sports Medicine Centre, Sydney, NSW. She is Team Doctor for the Sydney FC W-League football (soccer) team, Travelling Doctor with the Australian U17 women’s football (soccer) team, and Head Doctor for Australian Oztag and Australian Crossfit Games. SERIES EDITOR: Dr Seamus Dalton, MB BS, FAFRM, FACSP, Consultant Physician in Rehabilitation and Sports and Exercise Medicine, North Sydney Sports Medicine Centre, Sydney, NSW.