Individual Differences and Predictive Models of Lower Limb Muscle Strength after Resistance Training

Objective To compare the individual differences in lower limb strength changes after different resistance training programs and construct a predictive model for improving lower limb strength through resistance training.

Methods 193 participants completed a 12-week 70% 1RM training program (MIST12), with ineffective trainees completed 8 weeks (HIST8) and 12 weeks (HIST12) of training at 87% 1RM. Lower limb strength indicators included peak force during concentric (PTf) and eccentric (PTe) knee extension/flexion, isometric peak force (PTi), and counter movement jump (CMJ). Logistic regression was used to construct a predictive model for training effectiveness.

Results After MIST12 intervention, PTf, PTe, and CMJ significantly increased (P < 0.01), while PTi showed no significant change (P > 0.05). After HIST8 intervention, PTf and PTe showed no significant change (P > 0.05), while PTi and CMJ significantly increased (P < 0.05). After HIST12 intervention, PTf, PTe, PTi, and CMJ significantly increased (P < 0.05). No significant differences were found in the proportion of low respondents in PTf and PTe among the three programs (P > 0.05), while there was a significant difference in the proportion of low respondents in PTi and CMJ (P < 0.05). The AUC values for the predictive models of PTf, PTe, PTi, and CMJ training effectiveness were 0.609, 0.602, 0.684, and 0.719, respectively. Back testing showed no significant differences between predicted values and actual values (P > 0.05).

Conclusion Individual differences exist in improving lower limb muscle strength through resistance training. Initial strength, training program, and muscle thickness are predictive factors for the effectiveness of lower limb strength training. They should be considered important factors in developing personalized strength training guidance for different strength goals.