High - Intensity Interval Training : New Insights

Regular endurance training improves performance during tasks that rely mainly on aerobic energy metabolism, in large part by increasing the body’s ability to transport and utilize oxygen and by altering substrate metabolism in working skeletal muscle (Saltin & Gollnick, 1983). In contrast, highintensity “sprint”-type exercise training is generally thought to have less of an effect on oxidative energy provision and endurance capacity. However, many studies have shown that high-intensity interval training (HIT) — performed with suffi cient volume for at least several weeks — increases peak oxygen uptake (VO 2 peak) and the maximal activities of mitochondrial enzymes in skeletal muscle (Kubekeli et al., 2002; Laursen & Jenkins, 2002; Ross & Leveritt, 2001). Recent evidence suggests that many adaptations normally associated with traditional high-volume endurance training can be induced faster than previously thought with a surprisingly small volume of HIT. The present article briefl y summarizes skeletal muscle adaptations to HIT and highlights recent work that sheds new light on the potency of HIT to induce rapid skeletal muscle remodeling and improve exercise capacity.