Oxygen Uptake, Heart Rate, and Lactate Responses for Continuous Forward Running and Stop-and-Go Running With and Without Directional Changes.

Bekraoui, N, Boussaidi, L, Cazorla, G, and Leger, L. Oxygen uptake, heart rate, and lactate responses for continuous forward running and stop-and-go running with and without directional changes. J Strength Cond Res 34(3): 699-707, 2020-The purpose of this study is to measure and quantify the differences for the gross oxygen uptake (V?o(2)), heart rate (HR), and blood lactate ([LA]) responses to various modes of in-line running. Twelve healthy participants did an indirect continuous multistage field test to determine the maximal aerobic speed (MAS) before randomly performing in separate sessions 1 of the 3 running protocols at 3 intensities (60, 70, and 80% MAS) (a) in-line continuous running (IR), (b) fractioned running (FR) with stop and go every 20 m, and (c) 20-m shuttle run (SR). V?o(2) varied between 34.2 +/- 2.5 and 54.6 +/- 5.4 ml center dot kg(-1)center dot min(-1), HR between 141 +/- 14 and 184 +/- 9 b center dot min(-1), and [LA] between 4.2 +/- 0.8 and 6.6 +/- 0.9 mmol center dot L-1. In-line continuous running V?o(2) was lower than those of SR and FR at all intensities (p < 0.05). However, SR V?o(2) were higher than those of FR at 80% MAS only. Heart rate was similar in SR and FR but lower in IR at all intensities (p < 0.05). No significant differences were recorded in [LA]. Because only V?o(2) was affected by the introduction of a 180 degrees angle directional change (SR vs. FR) at 80% MAS, the use of HR to assess such activities at such intensities will result in underestimating workloads. This study offers new insights into V?o(2), HR, and [LA] associated with accelerations while running with and without directional changes at submaximal speeds.