Acute Effects of Aerobic Exercise Intensity on Lower-Limb Muscle Strength and Power in Youth Gymnasts

This study is a randomized crossover trial designed to examine the acute, intensity-dependent effects of aerobic exercise on lower-limb muscle strength, power, and power endurance in elite male youth gymnasts. In high-performance gymnastics training, aerobic conditioning is frequently combined with strength and technical training within the same day. However, the immediate neuromuscular effects of aerobic exercise performed at different intensities remain unclear in youth power-oriented athletes. Eighteen elite male youth gymnasts (aged 15-18 years), free from musculoskeletal injury and with national-level competitive experience, were recruited. After baseline assessments, each participant completed three aerobic exercise conditions in a randomized order, with a minimum washout period of 72 hours between sessions. The exercise conditions included high-intensity interval training (HIIT), moderate-intensity continuous training (MICT), and low-intensity steady-state exercise (LSD), all performed on a motorized treadmill. Exercise intensity was individually prescribed based on maximal heart rate and maximal aerobic speed determined during baseline testing. Lower-limb muscle strength and power were assessed before and 15 minutes after each exercise condition using force-platform-based tests, including countermovement jump, squat jump, drop jump, repeated countermovement jumps, and isometric mid-thigh pull. Subjective fatigue and muscle discomfort were also recorded using standardized rating scales. The primary objective of the study is to compare the acute changes in explosive power, power endurance, and maximal strength following aerobic exercise performed at different intensities. This study focuses on short-term neuromuscular responses rather than long-term training adaptations. Findings from this trial are expected to provide practical evidence for optimizing the sequencing of aerobic and strength-power training in elite youth gymnastics.