Reducing the volume of sprint interval training does not diminish maximal and submaximal performance gains in healthy men

Abstract

Together, these results indicate that reducing SIT work-interval duration from 30 to 15 s had no impact on training-induced increases in aerobic or anaerobic power, or on increases in lactate threshold (absolute) and critical power.

Modified sprint interval training protocols. Part I. Physiological responses

“…While the current investigation involved acute exercise, SIT protocols involving 10-, 15-, and 20-s bouts of intense exercise have shown significant improvements in aerobic and anaerobic performance (Hazell et al 2010;Ma et al 2013;Zelt et al 2014) as well as cardiometabolic health (Metcalfe et al 2012;Gillen et al 2014Gillen et al , 2016) over 2-12 weeks of training. Therefore, our acute data combined with these chronic training adaptations emphasize the importance of peak power generation during the initial seconds (≤15 s) of a SIT bout, which may be a more potent metabolic stimulus for driving adaptive mechanisms than the maintenance of power output that follows (Hazell et al 2010).…”

“…Interestingly, SIT-induced improvements in aerobic and anaerobic parameters (i.e., V O 2max , time-trial performance, Wingate power) as well as cardiometabolic health (i.e., muscle oxidative capacity, insulin sensitivity) are not compromised with even shorter work bouts involving 10 s (Hazell et al 2010), 15 s (Zelt et al 2014), and 20 s Metcalfe et al 2012;Gillen et al 2014Gillen et al , 2016 of supramaximal exercise. When considering the metabolic demands of SIT (predominantly anaerobic), a traditional 30-s bout is characterized by rapid peak power generation during the initial seconds of exercise (<10 s) followed by a precipitous power decline over the remainder of the effort.…”

“…Similar benefits are achieved with a more intense form of intermittent exercise known as sprint interval training (SIT) that involves supramaximal (>100% V O 2max ) work bouts, traditionally structured as four to six 30-s "all-out" efforts separated by 4 min of recovery . The potent physiological effects of SIT are highlighted by numerous studies reporting central (cardiovascular) and peripheral (muscular) adaptations that facilitate increases in both aerobic (Gibala et al 2006;Burgomaster et al 2008;MacPherson et al 2011;Hazell et al 2014a) and anaerobic (MacDougall et al 1998;Hazell et al 2010;Zelt et al 2014) performance. Additionally, SIT has been shown to improve body composition (i.e., decreased fat mass, in-creased lean mass) following 2-6 weeks of training, despite only 2-3 min of actual exercise performed per session (Whyte et al 2010;MacPherson et al 2011;Hazell et al 2014a).…”

Impact of low-volume, high-intensity interval training on maximal aerobic capacity, health-related quality of life and motivation to exercise in ageing men

“…Using a lowfrequency protocol comprising one session per week with bouts at 80 % maximum work rate to volitional exhaustion, they demonstrated a 13 % increase inV O 2max over 3 months. Similarly, there is evidence that reducing the volume of work within HIIT sessions, but maintaining their frequency at three sessions per week does not adversely impact on the improvements in aerobic capacity in young men (Matsuo et al 2014;Zelt et al 2014).…”

Effect of Number of Sprints in an SIT Session on Change in V˙O2max

“…Therefore, effective SIT protocols with fewer sprint repetitions will likely offer the best chance 260 of sedentary target populations taking up and adhering to a SIT intervention for improving 261 health (18) SIT are caused by improved skeletal muscle oxygen extraction due to increased mitochondrial 284 density (22,36,57,65,77). Although it remains unclear whether the improvement in V O2max 285 with SIT is due to central or peripheral adaptations, we propose that both increased blood 286 volume and increased mitochondrial density could plausibly be explained by the rapid 287 glycogen depletion associated with supramaximal exercise (51).…”