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 Léger, 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[Combining Dot Above]O2), 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[Combining Dot Above]O2 varied between 34.2 ± 2.5 and 54.6 ± 5.4 ml·kg·min, HR between 141 ± 14 and 184 ± 9 b·min, and [LA] between 4.2 ± 0.8 and 6.6 ± 0.9 mmol·L. In-line continuous running V[Combining Dot Above]O2 was lower than those of SR and FR at all intensities (p < 0.05). However, SR V[Combining Dot Above]O2 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[Combining Dot Above]O2 was affected by the introduction of a 180° 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[Combining Dot Above]O2, HR, and [LA] associated with accelerations while running with and without directional changes at submaximal speeds.

Oxygen uptake and heart rate response of 6 standardized tennis drills.

The purpose of this study was to compare the oxygen uptake of various on-court tennis drills. Eleven tennis players were monitored with a portable metabolic device to measure oxygen uptake of 6 different tennis drills at low and high speeds. The 6 drills were done with or without striking the ball, over half or full-width of the court, in attack or defense mode, using forehand or backhand strokes. Oxygen uptake values (mean ± SD) ranged from 33.8 ± 4.2 to 42.3 ± 5.1 mL·kg⁻¹·min⁻¹ when running at low speed on the full-width court in defense mode without striking the ball and when running at high speed on the full-width court in attack mode while striking the ball, respectively. Specific differences were observed. Attacking mode requires 6.5% more energy than defensive playing mode. Backhand strokes demand 7% more energy at low speed than forehand ones. Running and striking the ball costs 10% more energy than running without striking the ball. While striking the ball, shuttle running on half-width court costs 14% more energy than running on full-width courts. The specificity of the oxygen uptake responses obtained for these various tennis drills gives an improved representation of their energy cost and could be used to optimize training loads.