Research has shown that an active lifestyle, which includes regular exercise, promotes physical capacity, quality of life and self-esteem, as well as reducing the risk of certain diseases. In this area, the effects of aerobic exercise have received particular attention because of its link with a reduced risk of cardiovascular disease.

Evidence for the benefits of regular aerobic activity include its effects in producing increased concentrations of high density lipoprotein cholesterol (HDL-C), and the proportion of HDL-C/low density lipoprotein cholesterol (LDL-C). The implications of these changes have been linked to the prevention or slowing down of atherosclerotic process and consequently have clear benefits to an individual’s cardiovascular health. In addition, exercise has also been shown to decrease total cholesterol, triacylglycerol, and very-low density lipoprotein.

It is therefore unfortunate that even though the benefits of regular exercise have been widely publicised, the findings of the Allied Dunbar National Fitness Survey and a recent study in the US indicate that the large majority of people do not reach the activity levels required to have a beneficial effect on their health. Few are succeeding in incorporating the traditionally prescribed 20-30 min of vigorous exercise, 3-5 times a week into their lifestyle.

Reasons offered for not participating in physical activity include a lack of time and not being the ‘sporty’ type. Therefore to overcome these barriers, the health promoter has recently tried to convey to the general population that a physically active lifestyle is not synonymous with sport and that appropriate forms of exercise can be included within an individual’s daily routine without placing greater demands upon their time.

Furthermore, it is recognised that the formation of exercise habits is an essential stepping-stone towards regular exercise participation and adherence. Consequently completing short bouts of exercise throughout the day would seem to be an eminently suitable way of exercising, but has yet to be proven to be as effective as the traditionally prescribed 20-30 minutes sustained bout of moderately vigorous exercise.

In 1995 the Centre for Disease Control and Prevention and American College of Sports Medicine published a statement suggesting that health benefits may be accrued from accumulating 30 minutes of moderate intensity exercise during a day. However, to date, research evidence on the effects of accumulated short bouts of activity is limited and the findings are sometimes inconsistent.

For example, some studies on the effects upon aerobic fitness report that exercise regimens consisting of repetitive short bouts are less effective than single prolonged bouts at improving aerobic fitness of those who previously did not exercise on a regular basis or who previously exercised for less than 60 minutes per week. Conversely, others have found little difference in the effectiveness of continuous and accumulative bouts with untrained males and individuals whose habitual exercise was less than 60 min/week.

Similarly research into the effects of accumulated exercise upon blood lipids has also been unequivocal. Some researchers have suggested that accumulative bouts of daily exercise could be more effective in enhancing blood lipid profile than a singly daily bout, whereas others have found neither accumulated or single bouts of daily exercise to produce any change in blood lipid.

The Department of Sport and Exercise Science, Canterbury Christ Church University conducted a study with the aim of investigating the effects of single and accumulated short bouts of walking upon aerobic capacity and blood lipid profile. Fifty-six subjects aged between 40 and 66 completed the study. They were allocated into three walking groups and a control group. The three walking groups performed the same total amount of walking for 18 weeks, but completed it in bouts of differing durations and frequencies.

The results of the Study demonstrated that benefits to aerobic fitness may be achieved from both accumulated and extended bouts of exercise. However, whilst the benefits may be similar for aerobic fitness they are not for blood lipid profile. It would appear that the greatest health benefit may be gained from extended session rather that accumulated bouts of exercise - although for sedentary/low activity members of the population any improvement in these factors may be considered desirable.

Furthermore, these findings have demonstrated that the benefits for aerobic fitness and blood lipid profile may be achieved from exercise bouts of 15 minutes or more (at 70-75% of an individual’s VO2 max) over a relatively short time span (18 weeks) for about 150 - 175 minutes per week.

Consequently, these findings suggest that fitness and health benefits may be gained from moderate intensity exercise accumulated in 15 minute bouts during a day and could provide an effective exercise prescription for those who find it difficult to achieve the traditionally prescribed 20-30 min prolonged bout of physical activity.

Summary

Accumulated bouts of exercise are as effective as a larger single bout for improving aerobic fitness.

Larger single bouts of exercise are more effective than accumulated bouts for improving blood lipid profile.

To gain fitness and health benefits one should engage in exercise for 15 minutes, at about 70% VO2 max, on a daily basis.

However, for some personnel, initially prescribing accumulated short bouts of exercise in order to establish the ‘exercise habit’ may still be the most appropriate way to introduce activity into a sedentary persons lifestyle.

Source: http://www.meirafitness.com

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