14 Jan Fewer Workout Repetitions May Be At Least As Beneficial For Health Benefits
MedicalResearch.com Interview with:
Dr Niels Vollaard
Lecturer in Health and Exercise Science
Faculty of Health Sciences and Sport
MedicalResearch.com: What is the background for this study? What are the main findings?
Response: Although the health benefits of regular exercise are undisputable, many people do not manage to achieve the minimum recommended amount of exercise. Because lack of time is a commonly identified reason for not doing enough exercise, over the past decade researchers have increasingly focussed on sprint interval training (SIT) as a time-efficient alternative to aerobic exercise. However, while most SIT protocols do indeed only include a short duration of sprint exercise, they also require recovery periods after each sprint. Therefore, the total training time commitment per session tends to be close to half an hour, which is no less than what is recommended for less strenuous moderate intensity exercise.
To date, most sprint interval training studies have used the protocol that was employed in one of the first studies to look at aerobic adaptations following repeated sprints. This protocol consists of 6 repetitions of 30-second ‘all-out’ sprints. Very few studies have attempted to justify why this number of sprint repetitions would be optimal or even appropriate. Nonetheless, the number of sprint repetitions is of clear importance, as fewer sprints would result in more time-efficient training sessions. Thus, recent years have seen increasing interest in the benefits of SIT protocols with fewer sprints, which makes the protocol shorter and easier. However, up to now it remained unclear what the impact is of the number of sprint repetitions on key markers of health, such as maximal aerobic fitness (VO2max). This is of importance, as VO2max is the best predictor of risk of future disease and premature death.
MedicalResearch.com: What should readers take away from your report?
Response: The current meta-analysis clearly demonstrates that sprint interval training protocols with fewer sprint repetitions are not associated with attenuated improvements in VO2max, and may even be more effective. The magnitude-based inference estimated that the chance that performing fewer sprints is more effective is ~63%, and that the chance that this is less effective is 0%. This is a surprising finding as it means that performing a lower volume of exercise is associated with a more pronounced adaptation. To our knowledge there are no other types of exercise for which this is the case (providing that the intensity is kept constant in the comparison). The implication of our finding is that SIT as an alternative intervention for improving key health markers can be made more time-efficient as well as less tiring, both of which can be expected to enhance the uptake and adherence to sprint interval training by people who currently perceive lack of time to be a main barrier to performing sufficient exercise.
MedicalResearch.com: What recommendations do you have for future research as a result of this study?
Response: This research firmly established that performing fewer sprint repetitions in a SIT protocol is not associated with diminished adaptations for VO2max, and may even be more effective. However, the physiological reasons for this surprising finding remain unclear. As VO2max is a key marker of health, an understanding of the mechanisms by which exercise improves VO2max is of importance. Contrasting differences in acute and chronic molecular and physiological responses to various SIT protocols and aerobic exercise may help us to elucidate the mechanisms by which VO2max increases. Furthermore, a better understanding of these mechanisms may help us develop optimised and/or personalised interventions for improving health and reducing risk of chronic diseases like Type 2 diabetes and cardiovascular disease.
MedicalResearch.com: Is there anything else you would like to add?
Response: I am a researcher at the University of Stirling. I have no financial interest in promoting sprint interval training. My work has been funded by Diabetes UK and Nuffield Health.
MedicalResearch.com: Thank you for your contribution to the MedicalResearch.com community.
Niels BJ Vollaard, Richard S Metcalfe, Sean Williams. Effect of Number of Sprints in a SIT Session on Change in VO2max. Medicine & Science in Sports & Exercise, 2017; 1 DOI: 10.1249/MSS.0000000000001204
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