Previous research has shown that, once diet has been accounted for, scientists cannot consistently explain weight increases simply by lower levels of physical activity or decreased exercise over time. Therefore, a team from the National Institute of Health and Nutrition in Tokyo, Japan, led by Shigeho Tanaka, tested whether the frequency and duration of exercise performed influences the degree of fat utilisation by the body in nine healthy young men at an average age of 22.2.
During two 39-hour sessions of two nights and three days, the participants completed 85 minutes of exercise on a cycling ergometer at a workload of 5.5 metabolic equivalents, in a respiratory chamber that allows carbon dioxide and oxygen measurement. For three days before this, the men also consumed a high carbohydrate calorie-controlled diet, and ate four high-fat meals during their activity. In the first session, the participants performed continuous exercises, whilst in the other session, the same type and difficulty of exercise was performed for 5 minutes every 30 minutes a total of 17 times.
The results, which were reported in Medicine and Science in Sport and Exercise, were that the intermittent physical activity session produced a greater fat, rather than carbohydrate, utilisation for fuel than the continuous session. Yet, the researchers admit that these results must be taken with a pinch of salt. As they wrote in their report, ‘Because these results were obtained from only a few subjects during a short-term laboratory experiment, additional longitudinal studies and intervention studies are needed to confirm whether intermittent physical activity rather than continuous physical activity is effective for preventing obesity.’
Yet this did not prevent them from making the conclusion that, ‘the present study specifically suggests that the intervals between dynamic body movements should be as short as possible for more efficient utilization of ingested fat.’