Abstract: BACKGROUND: Youth is a critical window for physical development in the human body. During this stage, optimization of skeletal muscle function—including muscle strength, power output, and muscular endurance—is not only essential for athletic performance but also serves as a frontline defense against muscle decline and metabolic disorders caused by modern lifestyles. Meanwhile, cardiorespiratory endurance reflects the overall function of the cardiovascular and respiratory systems, which is a key predictor of health risks.
OBJECTIVE: To investigate the effects of different arrangement order of strength and endurance training (strength priority vs. endurance priority) on lower limb skeletal muscle function (maximum strength and strength endurance) and aerobic metabolic capacity (maximum oxygen uptake) in young people.
METHODS: Thirty healthy young college students from Hebei Sport University were randomly divided into three groups: strength priority group (n=10), endurance priority group (n=10) and control group (n=10). The strength priority group received strength training followed by endurance training, the endurance priority group had the opposite order, and the control group maintained daily activities. The intervention in each group lasted for 8 weeks, twice a week. The one repetition maximum (1RM) in squat/deadlift of the lower limb (maximum strength), the maximum repetitions at 70% 1RM squat/deadlift (strength endurance), and maximal oxygen uptake (estimated by indirect methods) were measured before and after the intervention.
RESULTS AND CONCLUSION: After 8 weeks of intervention, 1RM squat/deadlift were significantly increased in strength priority group (P < 0.05, P < 0.01), and the maximum repetitions at 70% 1RM squat/deadlift were significantly increased (P < 0.01). In the endurance priority group, the maximum repetitions at 70% 1RM squat/deadlift were significantly increased (P < 0.01), but there was no significant change in 1RM squat/deadlift. The maximum oxygen uptake increased significantly in the endurance priority group (P < 0.05), remained unchanged in the strength priority group, and decreased significantly in the control group (P < 0.05). There were significant differences in the maximum repetitions at 70% 1RM squat/deadlift and maximum oxygen uptake between groups (P < 0.01), and the maximum oxygen uptake in the endurance priority group was significantly higher than that in the strength priority group (P < 0.05) and control group (P < 0.01). The above results suggest that, during synchronic training, the priority of strength training is more conducive to improving the maximum strength of the lower limbs and maintaining aerobic capacity in young people, while the priority of endurance training is more conducive to improving the strength endurance and aerobic metabolic capacity.

Key words: synchronic training, training sequence, youth population, strength, endurance, lower limbs, skeletal muscle