An interventional study of 8 x 30 m Repeated Sprint Exercise in Exercise-Induced Fatigue, sponsored by Pamukkale University. Completed at 1 site in Turkey (Türkiye). Open to male participants aged 18 Years to 26 Years, including healthy volunteers. Per ClinicalTrials.gov, last updated 2026-08-03.
Sponsored by Pamukkale University · Not applicable, Interventional, and Basic science
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.
Pamukkale University is the lead sponsor of 331 studies on the registry; 61 are open to participants now.
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Exclusion Criteria:
Participants complete an 8 × 30 m repeated sprint exercise protocol with maximal effort and 25 seconds of active recovery between sprints.
Other: 8 x 30 m Repeated Sprint Exercise
Participants perform eight 30-m maximal sprints under field conditions. A 25-second active recovery period consisting of light jogging is provided between consecutive sprints. Before the repeated sprint protocol, participants complete a standardized 10-minute warm-up consisting of low-intensity running, dynamic mobility exercises, and progressive acceleration runs.
Heart Rate Variability: RMSSD
RMSSD was calculated from 5-minute R-R interval recordings obtained using a Polar H10 chest strap and analyzed with Kubios HRV Standard software. RMSSD was expressed in milliseconds and used as an indicator of parasympathetic cardiac autonomic recovery.
Time frame: Baseline, 5 minutes, 30 minutes, and 24 hours after the repeated sprint protocol.
Baseline Muscle Oxygen Saturation
Baseline muscle oxygen saturation (SmO2) was measured as a percentage using portable Moxy Monitor near-infrared spectroscopy sensors placed on the vastus lateralis and biceps femoris muscles of the dominant leg.
Time frame: Immediately before the repeated sprint protocol.
Minimum Muscle Oxygen Saturation
The lowest muscle oxygen saturation (SmO2) value recorded during the repeated sprint protocol was determined separately for the vastus lateralis and biceps femoris muscles and expressed as a percentage.
Time frame: During the 8 × 30 m repeated sprint protocol.
Muscle Oxygen Desaturation Difference
The muscle oxygen desaturation difference was calculated separately for the vastus lateralis and biceps femoris as baseline SmO2 minus minimum SmO2 and expressed in percentage points.
Time frame: Baseline and during the 8 × 30 m repeated sprint protocol on Study Day 1.
Thirty-Second Muscle Reoxygenation
Muscle oxygen saturation was recorded 30 seconds after completion of the repeated sprint protocol using NIRS sensors placed on the vastus lateralis and biceps femoris muscles and expressed as a percentage.
Time frame: 30 seconds after completion of the repeated sprint protocol.
Muscle Reoxygenation Rate
Muscle reoxygenation rate was calculated separately for the vastus lateralis and biceps femoris using the formula \[(30-second reoxygenation SmO2 minus minimum SmO2) / 30\] and expressed as percentage points per second.
Time frame: During the first 30 seconds after completion of the repeated sprint protocol.
Countermovement Jump Height
Countermovement jump height was measured in centimeters using the My Jump 2 smartphone application. Three valid trials were performed at each time point, and the best valid trial was used for analysis.
Time frame: Baseline, 10 minutes after the repeated sprint protocol, and 24 hours after the protocol.
Blood Lactate Concentration
Blood lactate concentration was measured in mmol/L using a Lactate Plus portable analyzer with capillary blood samples obtained from the fingertip.
Time frame: Immediately before and 3 minutes after the repeated sprint protocol.
Rating of Perceived Exertion
Perceived exertion was assessed using the Borg CR10 scale ranging from 0 to 10, where higher values indicate greater perceived exercise intensity.
Time frame: Immediately after completion of the repeated sprint protocol.
Sprint Time Across Repetitions
Completion time for each of the eight 30-m maximal sprints was recorded in seconds using a Witty wireless electronic timing gate system.
Time frame: During each of the eight repetitions of the repeated sprint protocol on the test day.
Best Sprint Time
The fastest completion time among the eight 30-m maximal sprint repetitions was recorded in seconds.
Time frame: During the 8 × 30 m repeated sprint protocol on the test day.
Mean Sprint Time
The arithmetic mean of the completion times recorded for the eight 30-m maximal sprint repetitions was calculated and expressed in seconds.
Time frame: During the 8 × 30 m repeated sprint protocol on the test day.
Total Sprint Time
The sum of the completion times recorded for all eight 30-m maximal sprint repetitions was calculated and expressed in seconds.
Time frame: During the 8 × 30 m repeated sprint protocol on the test day.
Sprint Performance Decrement
Sprint performance decrement was calculated as \[(total sprint time / (best sprint time × number of sprints)) - 1\] × 100. Higher values indicate a greater decline in repeated sprint performance.
Time frame: Calculated from the eight sprint times recorded during the repeated sprint protocol on the test day.
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