Background
Elite athletes competing in physically demanding sports should have little concern about meeting recommended guidelines on physical activity to accrue health benefits. However, sedentary behaviour is now considered a health risk factor independent of physical activity time,1–5 and is recognised in updated public health guidelines that advise against prolonged sedentary time.6
There has been very little research on athletes’ physical activity behaviour outside elite sport. In the short term, athletes’ lifestyles may compromise their recovery and performance. In the long term, poor lifestyles may pose health risks after the athlete has retired.
Sedentary behaviour has been defined as any waking behaviour characterised by an energy expenditure under 1.5 metabolic equivalents (MET; one MET is the same as 1 kcal/kg/hour and is roughly equivalent to the energy cost of not moving) while in a sitting or reclining posture.7 In adults, excessive sitting has been independently associated with adverse health, including abnormal glucose tolerance and type 2 diabetes, the metabolic syndrome, obesity, cardiovascular disease and mortality.2 ,8 ,9
Epidemiological studies have demonstrated a correlation between sedentary time and health risk.10–12 Every 2 h of daily television viewing has been associated with a 20% increased risk of type 2 diabetes, and 13% increased risk of all-cause mortality, independently of physical activity.13 ,14 Sitting for more than 10 h per day has been associated with higher body mass index and waist circumference, systolic and diastolic blood pressure, total serum cholesterol, triglycerides and non-fasting glucose levels, compared to those reporting a total sitting time of less than 4 h per day.15 In a controlled trial, replacing sitting with just 2 min of walking every 20 min was shown to reduce serum insulin and postprandial blood glucose by 24%, and lower blood pressure by a mean of 2–3 mm Hg.16 These findings suggest that adults should be encouraged to reduce their daily total sedentary time.
What are the new findings
Whilst exceeding recommended levels of physical activity for health and fitness, professional footballers spend the majority of their leisure time in sedentary activity.
The majority (79%) of waking hours (excluding training/matches) was spent sedentary (500.6 min±59.0 per day).
These levels of sedentariness are far greater than comparable data published on non-athlete and athlete samples of a similar age and body mass index.
How might it impact on clinical practice in the near future
These findings raise important questions over leisure time management for optimum recovery, performance and perhaps reducing injury risk.
There is a likelihood of imbalance between physical activity and sedentariness following retirement, which, coupled with the possibility of a less athletic diet and increasing age, poses mounting risk factors for chronic disease.
Interventions could be provided by club medical staff and via professional sports governing bodies or athlete associations.
This study indicates a necessity to explore objective sedentary behaviour profiles and optimal recovery more widely and deeply in athletes.
The benefits of light intensity activity (1.6–3.0 METs) such as standing and gentle walking are gaining interest, having been shown to improve blood glucose profiles,17 as well as lipoprotein lipase activity and therefore triglyceride and high-density lipoprotein cholesterol levels, independently of moderate and vigorous physical activity.18 Genetics studies on muscle biopsy tissue have shown that compared with uninterrupted sitting, activity bouts favourably promote the expression of proteins modulating anti-inflammatory and anti-oxidative pathways.19 The procoagulant effects of prolonged sitting can also be ameliorated.20
Excessive sedentary time is also likely to have implications on recovery and therefore sport performance. Muscle soreness following increased or unaccustomed exercise has been linked with reduced strength and performance.21 Studies involving short bouts of high intensity exercise, making them applicable to many sports including football, have shown that active recovery strategies, including light and moderate intensity activity, appear favourable when compared with passive (sedentary) recovery. 22 ,23 Relative rest is necessary for recovery, but the impact of prolonged sedentariness on recovery and therefore athletic performance or injury risk is poorly understood.
Given these causes for concern, and the dearth of objective data on the physical activity behaviour of elite athletes outside of sport, we investigated post-training (or leisure-time) physical activity behaviour in elite professional footballers during the English Premiership football season.