Exercise Selection Differentially Influences Lower Body Regional Muscle Development

This study had 2 primary aims (1) compare the effects of multi-joint vs. single-joint lower body exercise on regional muscular development of the quadriceps; and (2) compare the effects of exercises performed at different knee-joint angles on hypertrophy of the triceps surae.

Thirty young, resistance-trained participants unilaterally performed a combination of the following lower body exercises: leg press, leg extension, straight-leg toe press, and seated calf raise. The participants’ right legs were randomly allocated to perform 1 of the following 4 conditions: (1) leg press and straight-leg toe press; (2) leg-press and seated calf raise; (3) leg extension and straight-leg toe press; (4) leg extension and seated calf raise. Based on the allocated condition, the contralateral leg performed the other 2 exercises included in the protocol. Training was carried out twice per week on non-consecutive days for 8 weeks.

Point estimates for the rectus femoris outcomes favored the single-joint exercise intervention with posterior probabilities ranging from 0.910 ≤ P ≤ 0.990. In contrast, point estimates for the vastus lateralis outcomes favored the multi-joint exercise intervention with posterior probabilities ranging from 0.875 ≤ P ≤ 0.994. Regarding the triceps surae, the point estimate favored straight-leg plantar flexion for muscle thickness of the medial gastrocnemius (P = 0.991), with equivocal results observed for the lateral gastrocnemius and soleus.

Our findings indicate that exercise selection can influence regional hypertrophy of the muscles of the lower limbs and evidence of differences can be measured within 8 weeks.