150 minutes per week of moderate-intensity aerobic exercise is the recommendation for improving health markers in adults. However, adherence to these recommendations remains low in the overall population. Lack of time has been identified as one of the main barriers to becoming and remaining physically active.
High-intensity training (HIIT) as well as sprint interval training (SIT) has proven to be a time-efficient alternative for improving maximal aerobic capacity (VO2 max) as well as health markers. The most commonly used SIT protocol consists of 30 second intervals repeated 4-7 times, thus resulting in less than 4 minutes of high-intensity exercise per session.
Evidence suggests that the improvements in aerobic capacity can be attained with fewer sprints but the effect of various set volume on the magnitude of improvement remain unknown. A meta-analysis aimed to provide estimates of the modifying effect of the number of sprint repetitions in SIT protocols on the increase in VO2 max in untrained adult (1). Using data from 34 training studies and 418 participants the study showed that fewer repetitions with SIT does not attenuate the improvement of VO2 max, it may even enhance the effect.
Two studies investigated the effect of SIT protocol involving two sprints and observed a 10% increase in VO2 max (2, 3). The effect was also seen with SIT protocol involving 4 sprints (4). In conclusion, the available evidence suggests that SIT is possibly more effective at improving maximal aerobic capacity if fewer sprint repetitions are performed.
Article by Maria Ekblom, licensed physiotherapist and personal trainer.
Sources:
1. Vollaard N et al. Effect of Number of Sprints in a SIT Session on Change in VO2max. Medicine & Science in Sports & Exercise. 2017;:1.
2. Metcalfe R et al. European Journal of Applied Physiology. 2011;112(7):2767-2775.
3. Metcalfe RS et al. Physiological and molecular responses to REHIT. European journal of applied physiology. 2015;115(11):2321-34.
4. Gillen J et al. PLOS ONE. 2016;11(4):e0154075.
