Effect of different exercise intervals and work: Recovery ratios on oxygen uptake

This study examined the acute effect of varied interval lengths and work: recovery (W:R) ratios on the ability to reach and maintain a high level of aerobic power. Eight female rowers (mean XVO2max of 3.46 [0.64] L · min−1) completed 1 continuous and 7 interval sessions on a Concept II rowing ergometer. Exercise intensity was set at a power output that elicited each individual's VO2max (VO2maxPO) and work was terminated when PO remained below 90% VO2maxPO for 15 seconds. The interval protocols were a 2:1 W: R ratio for work intervals of 30 seconds, 1,2, and 3 minutes, respectively, and a 1:1 W: R ratio for respective work intervals of 1,2, and 3 minutes. Venous blood lactate concentration (BLa) was taken after the first 3 or 4 minutes of exercise and 2 minutes post‐exercise. Total work time (TWT) was greater (p ≤ 0.05) with an interval protocol compared with continuous exercise and decreased both when the exercise interval was lengthened and when the W:R ratio changed from 1:1 to 2:1. The average work‐rate VO2 (WVO2) was highest during the continuous and the two 3‐minute interval protocols. The greatest post BLa was observed after continuous work (13.7 ± 3.1 mmol L−1). During intermittent exercise sessions BLa increased (3.3 ± 1.7 to 9.0 + 1.3 mmol L−1) as the work interval was lengthened. The heart rate at the end of such recovery period was greater in the 30:15 (s) session and in the 2:1 W: R protocol, respectively, compared with the 1:1 W:R condition. The continuous exercise (4.2 ± 1.7 min) and both 3‐minute work intervals (3.1 ± 2.8 and 5.4 ± 3.7 min) induced the most time spent at VO2max but the 3:3 (min) design elicited the greatest TWT of these three conditions. Therefore, of the protocols studied, the 3:3 (min) interval was optimal for reaching and maintaining a high level of aerobic power when working at 90 to 100% of a PO that elicites VO2max in rowing exercise.