Effects of 4 different stretching strategies on power, speed, and muscle strength performance are discussed. 60 soccer players (aged 20.06±1.25, height 177.37±2.62cm, weight 73.40±6.01kg), as the research subject, are randomly divided into static group, static+dynamic group, dynamic group, dynamic+static group, and control group. With balance-order repeat-measure experimental design, counter movement jump, 50m sprint, and isokinetic strength are tested before, during, and after each experiment, with the experiment interval 72hr. The results reveal that 1) static stretching shows negative eff ects on power performance, dynamic stretching presents gain eff ects on power performance, and static+dynamic stretching is the best stretching strategy for power training, 2) static stretching appears signifi cant eff ects on speed performance, dynamic stretching could remarkably enhance speed performance, and dynamic stretching is the best stretching strategy for speed training, and 3) static stretching shows notably eff ects on muscle strength performance, dynamic stretching presents signifi cantly positive eff ects on muscle strength, and dynamic+static stretching is the best stretching strategy for muscle strength training.

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The study aimed to compare the effects of the progressive bodyweight and barbell-back squat training program (60–80% 1RM) on muscle strength, muscle thickness, and body fat percentage in sedentary young women. Thirteen sedentary young women (19.77 ± 0.83 years) were randomly divided into the progressive bodyweight (n = 6) or barbell squat (n = 7) group. Each program consisted of 2 weekly training sessions for 6 weeks. Muscle strength (isokinetic knee extensor and flexor muscle peak torque of each leg), muscle thickness (gluteus maximus, rectus femoris, and gastrocnemius muscles), along with body fat percentage were measured objectively at baseline and post-testing. For the muscle strength, both groups showed a significant increase in isometric peak torque of the knee extensor and flexor (p < 0.05). However, there were no significant be-tween-group differences in isometric peak torque of the knee extensor and flexor (p > 0.05), as well as the mean concentric peak torque of the knee H/Q ratio (p > 0.05). For the muscle thickness, significant increases were also found within the two groups (p < 0.05) and without significant differences between the two groups (p > 0.05). The percentage of body fat significantly improved in the barbell (pre. 28.66 ± 4.58%. vs post. 24.96 ± 5.91%, p = 0.044), but not in the bodyweight group (pre. 24.18 ± 4.63% vs post. 24.02 ± 4.48%, p = 0.679). Although all of the groups increased maximum strength and muscle mass, our results suggest that the barbell back squat training may optimize the gains for decreasing the body fat percentage.