This paper aimed to systematically review the literature regarding the effects of resistance training (RT) performed at longer-muscle length (LML) versus shorter-muscle length (SML) on proxy measurements for longitudinal hypertrophy.

We included studies that satisfied the following criteria: (1) be a resistance training intervention with a comparison of LML vs SML-RT; (2) assess both fascicle length (FL) and muscle size pre- and post-intervention; (3) involve healthy adults aged ≥ 18 years; (4) be published in an English-language journal, and; (5) have a minimum training intervention duration of 4 weeks. Three databases were searched in February 2024 (Google Scholar, PubMed/Medline, Scopus) for relevant articles, alongside 'forward' and 'backward' citation searching of articles included and additions via authors' personal knowledge. The results of studies were described narratively, compared, and contrasted. Eight studies met the inclusion criteria, totaling a sample size of 120.

Our results suggest that both muscle size and fascicle length increases may be greater following LML-RT versus SML-RT, suggesting LML-RT may lead to greater longitudinal hypertrophy than SML-RT. Notably, evidence is largely mixed; no studies to date have attempted to estimate serial sarcomere number changes from LML versus SML-RT, and all but one study used linear extrapolation methods to estimate FL, which has questionable validity. Therefore, the structural adaptations underlying hypertrophy from LML-RT remain undetermined.

In conclusion, results suggest that LML-RT may be superior to SML-RT for inducing muscle hypertrophy and, more specifically, longitudinal growth, though evidence is mixed.

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.