Challenging Traditional Training Regimens
Traditionally, exercise physiologists have recommended one of three regimens to improve aerobic power: continuous exercise at a moderate to high intensity; long, slow (low-intensity) exercise; or interval training. However, a growing body of research suggests that high-intensity interval training (HIT) is a time-efficient way to induce many adaptations normally associated with traditional endurance training. Scientists at McMaster University in Canada have studied the effects of training using short bursts of very intense cycling, interspersed with up to a few minutes of rest or low-intensity cycling for recovery.12 A common training mode employed is based on the Wingate test, a test that consists of 30 s of “all-out” cycling and generally produces mean power outputs that are two to three times higher than what subjects typically generate during a maximal oxygen uptake test.
In one study, young healthy subjects performed four to six 30 s sprints separated by 4 min of recovery, three times a week. These men showed the same beneficial changes in their heart, blood vessels, and muscles as another group who underwent a traditional training program involving up to an hour of continuous cycling, five days per week. Improvements in exercise performance—whether measured as cycling time to exhaustion at a fixed work intensity or in time trials that more closely resemble normal athletic competition—were comparable between groups, despite considerable differences in training time commitment.12 HIT appears to stimulate some of the same molecular signaling pathways that regulate skeletal muscle remodeling in response to endurance training, including mitochondrial biogenesis and changes in the capacity for carbohydrate and fat transport and oxidation. Researchers are currently studying whether “modified” forms of HIT—which might be safer and better tolerated by older, less fit individuals or people with metabolic diseases such as type 2 diabetes—are equally effective for improving health and fitness.