Three Minutes of All-Out Intermittent Exercise per Week Increases Skeletal Muscle Oxidative Capacity and Improves Cardiometabolic Health

We investigated whether a training protocol that involved 3 min of intense intermittent exercise per week — within a total training time commitment of 30 min including warm up and cool down — could increase skeletal muscle oxidative capacity and markers of health status. Overweight/obese but otherwise healthy men and women (n = 7 each; age = 2969 y; BMI = 29.862.7 kg/m2) performed 18 training sessions over 6 wk on a cycle ergometer. Each session began with a 2 min warm-up at 50 W, followed by 3620 s ‘‘all-out’ ’ sprints against 5.0 % body mass (mean power output:,450–500 W) interspersed with 2 min of recovery at 50 W, followed by a 3 min cool-down at 50 W. Peak oxygen uptake increased by 12 % after training (32.664.5 vs. 29.164.2 ml/kg/min) and resting mean arterial pressure decreased by 7 % (78610 vs. 83610 mmHg), with no difference between groups (both p,0.01, main effects for time). Skeletal muscle biopsy samples obtained before and 72 h after training revealed increased maximal activity of citrate synthase and protein content of cytochrome oxidase 4 (p,0.01, main effect), while the maximal activity of b-hydroxy acyl CoA dehydrogenase increased in men only (p,0.05). Continuous glucose monitoring measured under standard dietary conditions before and 48–72 h following training revealed lower 24 h average blood glucose concentration in men following training (5.460.6 vs. 5.960.5 mmol/L, p,0.05), but not women (5.560.4 vs. 5.560.6 mmol/L). This was associated with a greater increase in GLUT4 protein content in men compared to women (138 % vs. 23%, p,0.05). Short-term interval training using a 10 min protocol that involved only 1 mi