Long sprint intervals increase muscle oxygen consumption better than short ones

Physical activities such as running, walking, cycling and sprinting are known to use the musculoskeletal system and cause energy expenditure. Sprint interval training (SIT) is a type of sprinting exercise that involves cycles of intense exercise followed by a short rest period. The pattern of exercise and rest duration may influence the body's physiological responses to SIT.

In recent years, the field of sports physiology has seen increased interest in optimizing SIT protocols. This increase in interest is driving recognition of SIT's effectiveness in improving athletic performance and overall well-being, highlighting its versatility as a health and fitness tool.

In an attempt to highlight the benefits of SIT, a team of researchers from Japan, including Dr. Takaki Yamagishi from the Department of Sports Science and Research at the Japan Sports Science Institute and the Human Performance Laboratory at Waseda University Integrated Research Organization, and Professor Yasuo Kawakami, who directs the Human Performance Laboratory and is a member of the Department of Sports Science at Waseda University and conducted SIT experiments with healthy volunteers in a recent study.

The study was published in the journal of Medicine & Science in Sports & Exercise.

Explaining the motivation behind his research work, Yamagishi says, “Establishing the minimum dose of training required to achieve training effects such as aerobic fitness has been one of my main research interests. Thanks to the support of Professor Kawakami and other co-authors, as well as collaboration with Waseda University, this unique study using a multidisciplinary approach was made possible."

A team of researchers compared two different sprint interval exercises (SIE) in terms of total sprint duration and sprint-to-rest ratio. They analyzed the effects of SIE on physiological and metabolic responses by examining pulmonary oxygen uptake (V̇O2) levels and tissue oxygenation index (∆TOI) changes in the thigh muscles. They also used T2-weighted magnetic resonance imaging (MRI) to assess thigh muscle activation.

The researchers found that SIE20, which involved two 20-second sprints with 160 seconds of recovery, outperformed SIE10, which involved four 10-second sprints with 80 seconds of recovery. Although both SIE protocols significantly increased total and peripheral oxidative metabolism and core muscle activation, as demonstrated by increases in V̇O2, ∆TOI, and MRI T2 values, respectively, greater peripheral oxidative metabolism was achieved with SIE20. They also found that consecutive sprint repetitions in SIE10 did not correlate with greater oxidative metabolism.

Sprint interval exercise can stimulate beneficial physiological and metabolic responses through muscle activation and increased tissue oxygen consumption. Source: Medicine & Science in Sports & Exercise (2024). DOI: 10.1249/MSS.00000000000003420

In discussing the practical application and impact of this study, Yamagishi says, “In today’s fast-paced world, lack of time is a major barrier to regular physical activity. However, the exercises used in our study require less than 15 minutes to complete and provide significant health benefits.”

In conclusion, the results of this study may help fill important gaps in SIT research, such as the effects of minimum sprint duration and repetitions on aerobic and metabolic responses in humans. In-depth research on low-volume SIT may improve training programs and exercise regimens.

Yamagishi adds, “Exercise guidelines from major organizations such as the American College of Sports Medicine are updated every five to ten years, and we hope our study can be part of that process. Future studies on SIE could build on our findings to establish a dose-dependent relationship between exercise volume or intensity and the extent of training adaptations."