Muscle Oxygenation and Autonomic Recovery After Repeated Sprint in Competitive Soccer Players

Overview

This study evaluates the acute and short-term recovery responses to repeated sprint exercise in competitive male soccer players. Forty-eight licensed male soccer players complete an 8 × 30 m repeated sprint protocol under field conditions, with 25 seconds of active recovery between sprints. The study examines several aspects of recovery. Muscle oxygenation is assessed using portable near-infrared spectroscopy sensors placed on the vastus lateralis and biceps femoris muscles. Cardiac autonomic recovery is evaluated using heart rate variability measurements obtained at baseline, 5 minutes, 30 minutes, and 24 hours after the repeated sprint protocol. Countermovement jump performance is measured before the protocol, 10 minutes after the protocol, and 24 hours later. Sprint performance, blood lactate concentration, and perceived exertion are also recorded to characterize the physiological and performance demands of the repeated sprint protocol. The study aims to determine how muscle oxygenation, cardiac autonomic recovery, and neuromuscular performance change during the recovery period following repeated sprint exercise and whether these recovery indicators are associated with repeated sprint performance.

This study uses a single-group repeated-measures design to investigate muscle oxygenation, cardiac autonomic recovery, and neuromuscular performance responses following repeated sprint exercise in competitive male soccer players. A total of 48 licensed male soccer players participate in the study. Participants regularly train and compete in soccer and have at least four years of soccer training experience. During the measurement session, demographic and anthropometric characteristics are recorded first. Baseline measurements include heart rate variability, muscle oxygen saturation, blood lactate concentration, and countermovement jump performance. After a standardized 10-minute warm-up, participants complete an 8 × 30 m repeated sprint protocol. Each sprint is performed with maximal effort, and a 25-second active/light jogging recovery period is provided between sprints. Sprint times are recorded using an electronic timing gate system. Muscle oxygenation is continuously assessed using portable near-infrared spectroscopy sensors placed on the vastus lateralis and biceps femoris muscles of the dominant leg. The evaluated muscle oxygenation variables include baseline muscle oxygen saturation, minimum muscle oxygen saturation, desaturation difference, 30-second reoxygenation muscle oxygen saturation, and reoxygenation rate. Cardiac autonomic recovery is evaluated using heart rate variability derived from R-R interval recordings obtained with a Polar H10 chest strap. Five-minute HRV recordings are obtained at baseline, 5 minutes after the repeated sprint protocol, 30 minutes after the protocol, and 24 hours after the protocol. RMSSD and SDNN are used as the primary time-domain HRV parameters. Neuromuscular performance is evaluated using countermovement jump height before the repeated sprint protocol, 10 minutes after the protocol, and 24 hours after the protocol. Blood lactate concentration is measured before the protocol and at 3 minutes after the protocol. Rating of perceived exertion is recorded after completion of the sprint protocol using the Borg CR10 scale. The study is designed to characterize the time course of recovery following repeated sprint exercise and to examine relationships among sprint performance, muscle oxygenation, cardiac autonomic recovery, and neuromuscular performance. Because the study uses a single-group design without a control group, the findings are interpreted as recovery-related associations rather than evidence of causal effects.