The Scientific Basis for High-Intensity Interval Training

Abstract

While the physiological adaptations that occur following endurance training in previously sedentary and recreationally active individuals are relatively well understood, the adaptations to training in already highly trained endurance athletes remain unclear. While significant improvements in endurance performance and corresponding physiological markers are evident following submaximal endurance training in sedentary and recreationally active groups, an additional increase in submaximal training (i.e. volume) in highly trained individuals does not appear to further enhance either endurance performance or associated physiological variables [e.g. peak oxygen uptake (VO2peak), oxidative enzyme activity]. It seems that, for athletes who are already trained, improvements in endurance performance can be achieved only through high-intensity interval training (HIT). The limited research which has examined changes in muscle enzyme activity in highly trained athletes, following HIT, has revealed no change in oxidative or glycolytic enzyme activity, despite significant improvements in endurance performance (p < 0.05). Instead, an increase in skeletal muscle buffering capacity may be one mechanism responsible for an improvement in endurance performance. Changes in plasma volume, stroke volume, as well as muscle cation pumps, myoglobin, capillary density and fibre type characteristics have yet to be investigated in response to HIT with the highly trained athlete. Information relating to HIT programme optimisation in endurance athletes is also very sparse. Preliminary work using the velocity at which VO2max is achieved (V(max)) as the interval intensity, and fractions (50 to 75%) of the time to exhaustion at V(max) (T(max)) as the interval duration has been successful in eliciting improvements in performance in long-distance runners. However, V(max) and T(max) have not been used with cyclists. Instead, HIT programme optimisation research in cyclists has revealed that repeated supramaximal sprinting may be equally effective as more traditional HIT programmes for eliciting improvements in endurance performance. Further examination of the biochemical and physiological adaptations which accompany different HIT programmes, as well as investigation into the optimal HIT programme for eliciting performance enhancements in highly trained athletes is required.

Metabolic profile of a crossfit training bout

“…Improvements in body fat percentage were also noted; males incurred an average decrease of 4.2% while females experienced a 3.4% decrease. This finding is similar to investigations of other forms of high-intensity interval-type training and resistance exercise-based circuit training that have resulted in improved measures of fitness (Laursen & Jenkins, 2002). Franch et al (Franch, Madsen, Djurhuus, & Pedersen, 1998) showed that 6 weeks of intense interval training using 4 to 6 sets of 4 minute intervals resulted in a 6% improvement in VO2max and a greater increase in time to exhaustion at 85% VO2max compared to 6 weeks of continuous running (+93% vs. +67%, respectively).…”

Effect of Aerobic High-Intensity Interval Training on VO2max and Anaerobic Power in Cross-Country Skiers

“…Parallel with earlier findings [10,11,14], this study reported that high-intensity aerobic training is effective for improving VO 2max in cross-country skiers. It can be advantageous for endurance performance to slightly reduce intensity and use longer duration of intervals in endurance athletes [10].…”

“…Several studies have reported that similar effects of aerobic high-intensity endurance training on performance and aerobic characteristics [14]. Parallel with earlier findings [10,11,14], this study reported that high-intensity aerobic training is effective for improving VO 2max in cross-country skiers.…”

Roller-Ski Aerobic High-Intensity Interval Training Improves the VO2max and Anaerobic Power in Cross-Country Skiers

“…Several studies have reported that similar effects of aerobic high-intensity endurance training on performance and aerobic characteristics [19]. Parallel with earlier findings [12,15,19], it can be said that high-intensity aerobic interval training has significant effects on VO2max in crosscountry skiers. With the start of using the skating technique, importance of upper body anaerobic capacity stated by several studies [10,22].…”