vastus lateralis

This study examined how lower-body lengthened partial (LP) versus full range of motion (FULL) resistance training affects acute post-exercise signaling, chronic hypertrophy, and cellular adaptations of the vastus lateralis (VL) muscle in resistance-trained men. Eight males (22+/-1 years old, 5.6+/-1.4 years training) completed a crossover study whereby VL biopsies were collected pre-exercise and 0, 3, and 24 hours following LP and FULL leg extension bouts for transcriptomic and anabolic signaling analyses (Experiment 1). Another 16 males (26+/-5 years old; 8.0+/-4.9 years training) completed an 8-week, twice-weekly lower-body intervention using a within-subject design (Experiment 2). One leg was assigned to FULL and the contralateral leg to LP training across three exercises (leg press, leg extension, and lying leg curl). Pre- and post-intervention outcomes included VL muscle cross-sectional area (mCSA) summed across five equidistant MRI-derived transverse slices and mid-thigh VL biopsy outcomes. As a secondary outcome, other hip and thigh muscles from Experiment 2 MRI scans were assessed. Condition*Time interactions for all outcomes were assessed using linear mixed-effects models. In Experiment 1, both conditions produced similar time-dependent changes in the VL transcriptome and anabolic (mTORC1 and Hippo) signaling, but minimal between-protocol interactions. In Experiment 2, VL summed mCSA significantly increased over time (mean change: 9.3 cm sq., 95% CI [6.8, 11.8], P<0.001), but there was no clear evidence of differential change between protocols (LP−FULL change: −1.4 cm sq., 95% CI [−6.1, 3.8], P=0.640). Additionally, no significant interactions existed for type I fiber CSA (P=0.476), type II fiber CSA (P=0.350), type I fiber myonuclei (P=0.813), type II fiber myonuclei (P=0.589), type I and II satellite cell number (P=0.102 and P=0.797, respectively), or total RNA content (P=0.537). Despite these null VL-centric findings, secondary Experiment 2 analyses provided some evidence that whole hamstring hypertrophy was greater following LP versus FULL (LP−FULL change: 3.9 cm sq., 95% CI [−0.2, 7.9], P=0.058). In conclusion, 8 weeks of LP and FULL resistance training broadly elicit similar acute and chronic VL responses in previously trained men, though secondary hamstring findings suggest that differential responses may depend on exercises included in the resistance training program.

matched text: “vastus lateralis”

Background The effects of velocity-based resistance training (VBRT) in institutionalized older adults remain poorly explored. This protocol aims to describe a study designed to i) analyze the effects of a 9-month VBRT program on skeletal muscle size, muscle function, physical performance, disability, cognitive function and frailty in nursing home residents, ii) compare the impact of different velocity loss (VL) thresholds (10% vs. 20%), and iii) determine the residual effect of the intervention after 6 months exercise cessation. Methods Nursing home residents aged ≥65 years will participate in this experimental study. Participants will complete a 4-week control period followed by a 9-month VBRT program and 6 months of follow-up after exercise cessation. The intervention will consist of VBRT twice a week using the leg press exercise for 9 months. The participants will be randomly assigned to two VL groups: 10% vs. 20% VL, performing n repetitions at 60% of estimated maximal isometric force until reaching their prescribed VL. To minimize training volume differences, the 10% VL group will complete 4 sets, while the 20% VL group will complete 3 sets. Outcomes will include muscle size of rectus femoris and vastus lateralis (ultrasound), muscle function (sit-to-stand muscle power and force-velocity relationship parameters), physical performance (Short Physical Performance Battery and walking tests), disability (Barthel and Lawton Indexes), cognitive function (Mini-Mental State Examination) and frailty (Fried Phenotype and Frailty Trait Scale). The time course of the exercise-induced adaptations will be assessed throughout the study. Discussion We hypothesize that VBRT will exhibit meaningful benefits in muscle size, muscle function, physical performance, disability, cognitive function and frailty among institutionalized older adults, with no significant differences between 10% and 20% VL thresholds. While deconditioning is predictable after 6 months of exercise cessation, the investigated outcomes are expected to remain significantly and positively elevated compared to baseline values. This study will help to identify innovative actions to improve overall health and endorse exercise practice in older adults living in nursing homes. Trial Registration ClinicalTrials.gov , identifier NCT07027397.

matched text: “vastus lateralis”