vastus lateralis

The purpose of this study was to examine whether short-duration phase-change material cooling (PCM) applied at different temperatures influences acute recovery following fatigue induced by stretch-shortening cycle exercise (SSC). Sixty-four physically active participants were randomly assigned to 5°C, 10°C, or 15°C PCM cryotherapy group or a passive recovery control group. After completing a SSC fatigue protocol, participants underwent a 15-minute PCM intervention, and peak torque (PT), mean power, rate of force development (RFD), countermovement jump (CMJ) performance, Rating of perceived exertion (RPE), modified endurance ratio (MER), vastus lateralis (VL) and Rectus Femoris (RF) stiffness were assessed immediately after fatigue (Imm-fatigue), immediately after PCM cryotherapy (Imm-PCM), and 60 minutes post PCM cryotherapy (Post60-PCM). Mean power and RFD were significantly greater in PCM groups compared with the control group at Imm-PCM (P ≤ 0.01), with mean power remaining elevated in the 15°C PCM group at post-60-PCM (P ≤ 0.05). RPE was significantly lower in all PCM groups at Imm-PCM and post60-PCM compared with control (P ≤ 0.01). No between-group differences were observed for PT, CMJ, MER, or muscle stiffness, and no temperature-dependent effects were detected within the 5-15 °C. These findings indicate that 15-minute PCM cryotherapy selectively accelerates early-phase neuromuscular and perceptual recovery without affecting maximal strength, endurance capacity, or passive muscle mechanical properties. From an applied perspective, PCM cryotherapy may be an effective strategy to enhance explosive performance and perceived readiness during short recovery intervals in training or competition settings.

matched text: “vastus lateralis”

<h4>Background</h4>Neuromuscular fatigue can be characterized by an exercise-induced reduction in force-generating capacity involving both neural and muscular mechanisms. Previous research has suggested that the functional organization of the neuromuscular system differs between endurance-trained individuals and sedentary or recreationally active individuals. This difference may lead to distinct neuromuscular responses to fatigue. The aim of this study was to compare neuromuscular fatigue responses between endurance-trained (ET) and recreationally active (RA) males during a sustained submaximal isometric knee extension contraction.<h4>Methods</h4>Eleven ET and 11 RA participants performed maximal voluntary isometric contractions (MVIC) of the knee extensors (KE), followed by a trapezoidal contraction (ascending to 60% MVIC) and an isometric fatiguing task at 30% MVIC sustained to task failure. An additional MVIC was completed immediately post-fatigue task. High-density surface electromyography (HDsEMG) was simultaneously recorded from the vastus lateralis, and HDsEMG root mean square (RMS), median frequency (MDF) and muscle fibre conduction velocity (MFCV) were estimated. The MFCV-torque relationship during the ascending phase of the trapezoidal contraction (up to 60% MVIC) was assessed using the mixed linear model.<h4>Results</h4>Baseline MVIC of the KE did not differ between groups. The ET group showed a significantly lower rate of increase in MFCV (<i>p</i> < 0.001) during the ascending phase of the contraction and lower absolute MFCV at 60% MVIC (<i>p</i> < 0.001) compared to the RA group. During the sustained fatiguing task, both groups reached task failure at similar times with comparable MVIC reductions (∼25%). However, the RA group exhibited significant declines in both MDF (<i>p</i> < 0.001) and MFCV (<i>p</i> = 0.04), whereas these parameters remained unchanged in the ET group.<h4>Conclusion</h4>While ET and RA individuals exhibited similar levels of fatigue, the underlying neuromuscular mechanisms may differ. The ET group showed a lower rate of increase in MFCV with increasing voluntary force and unchanged MFCV and MDF during fatiguing contractions, whereas the RA group exhibited fatigue-induced decreases in both MFCV and MDF. These findings suggest that endurance training is associated with altered recruitment and/or muscle membrane properties, likely linked to differences in muscle fibre characteristics.

matched text: “vastus lateralis”