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Background Stroke-prone spontaneously hypertensive rats (SHRSP) exhibit slow-twitch muscle-specific hypotrophy compared with normotensive Wistar-Kyoto rats (WKY). Because slow-twitch muscles are prone to disuse atrophy, SHRSP may experience both disuse atrophy and impaired recovery from it. This study investigated the response of SHRSP to disuse atrophy and subsequent recovery, using WKY as a control. Results WKY and SHRSP were subjected to a 7-day tail suspension followed by reloading for 1, 3, and 7 days. The soleus of WKY and SHRSP showed similar atrophic rates following tail suspension; however, the recovery after reloading was delayed in SHRSP. Moreover, WKY, but not SHRSP, exhibited sarcomere structure disruption after tail suspension, followed by necrosis, inflammatory cell infiltration, and edema upon reloading. Phosphorylation of ribosomal protein S6 (RPS6), an indicator of protein translation, was significantly higher in tail-suspended WKY—but not SHRSP—than those in non-tail-suspended groups after reloading. p70-S6 kinase 1 (S6K1), an upstream protein of RPS6, was phosphorylated at Thr389 in a mechanistic target of rapamycin complex 1-dependent manner to the same extent in both WKY and SHRSP; however, the expression of p60-S6K1—a shorter isoform of p70-S6K1 that activates RPS6 without p60-S6K1 phosphorylation—significantly increased only in tail-suspended WKY compared with those in non-tail-suspended WKY and tail-suspended SHRSP. Previously, p60-S6K1 protein expression was thought to result from an alternative translation of the full-length S6K1 transcript that also produces other S6K1 isoforms. However, recent studies have identified a p60-S6K1-specific transcript, and our PCR results showed that this p60-S6K1-specific transcript, but not the full-length S6K1 transcript, was significantly increased only in tail-suspended WKY corresponding with the increase of p60-S6K1 protein expression. Conclusions SHRSP exhibited different phenotypes in disuse atrophy and recovery from it compared with WKY, which could be related to suppressed RPS6 phosphorylation associated with the lack of upregulation in p60-S6K1 expression. These findings suggest that p60-S6K1, in cooperation with p70-S6K1, activates RPS6 and promotes rapid recovery from disuse atrophy by enhancing the transcription of the p60-S6K1-specific transcript. The study also suggests a potential involvement of hypertension in disuse atrophy and its recovery.

Purpose: To determine the effect of vibrating rollers on skin blood flow after running for recovery from muscle fatigue. Method: 23 healthy runners, aged between 20 to 45 years, participated in a crossover trial. Muscle fatigue was induced by running, and recovery using a vibrating roller was determined before and after the intervention. Each subject was measured at three time points (prerun, postrun, and postroller) to compare skin blood flow perfusion and blood flow oscillation at the midpoint of the dominant gastrocnemius muscle. The results show that blood perfusion is greater when a vibrating roller is used than a foam roller, but there is no statistical difference. The analysis of blood flow oscillation shows that vibrating rollers induce 30% greater endothelial activation than a foam roller. Vibrating rollers significantly stimulate the characteristic frequency for myogenic activation (p < 0.05); however, the effect size is conservative.

Sarcopenia is characterized by decreased skeletal muscle mass and function with age. Aged muscles have altered lipid compositions; however, the role and regulation of lipids are unknown. Here we report that FABP3 is upregulated in aged skeletal muscles, disrupting homeostasis via lipid remodeling. Lipidomic analyses reveal that FABP3 overexpression in young muscles alters the membrane lipid composition to that of aged muscle by decreasing polyunsaturated phospholipid acyl chains, while increasing sphingomyelin and lysophosphatidylcholine. FABP3-dependent membrane lipid remodeling causes ER stress via the PERK-eIF2α pathway and inhibits protein synthesis, limiting muscle recovery after immobilization. FABP3 knockdown induces a young-like lipid composition in aged muscles, reduces ER stress, and improves protein synthesis and muscle recovery. Further, FABP3 reduces membrane fluidity and knockdown increases fluidity in vitro, potentially causing ER stress. Therefore, FABP3 drives membrane lipid composition-mediated ER stress to regulate muscle homeostasis during aging and is a valuable target for sarcopenia. Ageing leads to a loss of muscle mass and strength, called sarcopenia. Here, the authors show that fatty acid binding protein 3 (FABP3), a lipid chaperone, drives age-dependent lipidome remodeling in skeletal muscle and deteriorates muscle mass and contractility by modulating membrane fluidity and ER stress signaling.

•The correlation between low circulating levels of vitamin D and muscle metabolism disorders is documented in various contexts, including muscle recovery, atrophy, sarcopenia, and cachexia.•The powerful role of vitamin D receptor on muscle health is evident.•Correcting deficiency or insufficiency of vitamin D is essential for human health, and is of paramount importance for muscle tissue. The relevance of vitamin D to skeletal muscle metabolism has been highlighted in recent years. The interest arises from the important findings of studies demonstrating multiple effects of vitamin D on this tissue, which can be divided into genomic (direct effects) and non-genomic effects (indirect effects). Another important aspect to be considered in the study of vitamin D and muscle fiber metabolism is related to different expression of vitamin D receptor (VDR), which varies in muscle tissue depending on age, sex, and pathology. The correlation between low circulating levels of vitamin D and muscle metabolism disorders is documented in various contexts, including muscle recovery, atrophy, sarcopenia, and cachexia. The aim of this review was to analyze recent results of both in vitro and in vivo studies to address the relationship between vitamin D and skeletal muscle biology. The words muscle atrophy, muscle hypertrophy, sarcopenia, and cachexia were crossed over with vitamin D in a Pubmed search. All original contributions, along with reviews on the topic, were included, and no publications in the past 10 y were discarded. The papers retrieved different topics such as vitamin D in skeletal muscle; vitamin D in circulation; vitamin D, sarcopenia, and muscle atrophy; vitamin D and cachexia; and vitamin D and muscle recovery.

Muscle hematomas can exacerbate inflammation, delay healing, and reduce function after muscle injury. This study examined whether early hematoma removal promoted recovery in a rat model of tibialis anterior muscle laceration. Hematomas were surgically removed 6 h after injury and compared with untreated animals. Histological analysis revealed that the hematoma removal group had a significantly reduced hematoma size 24 h after injury and a significantly reduced abnormal tissue area on days 3 and 14. Furthermore, the hematoma removal group demonstrated better muscle strength recovery at 3, 14, and 28 days post-injury. Gene expression analysis of the injured muscle tissue revealed that the expression levels of several genes related to inflammation and inflammatory pain (IL-6, IL-10, IL-1β, TNF-α, IL-1Ra, COX-1, COX-2, NGF) and macrophage marker molecules (CD68, ADGRE1, CD206, Arg1) during the acute phase were significantly lower in the hematoma removal group compared to the control group. No significant differences were observed in the transcription levels of the genes related to myogenic differentiation. In summary, early surgical hematoma removal in a rat laceration model reduced inflammation and abnormal tissue volume and promoted muscle strength recovery. This study provides new evidence suggesting that early hematoma removal after skeletal muscle injury is beneficial.

BackgroundPreoperative skeletal muscle deficiency is an established risk factor for poor survival outcomes in patients with renal cell carcinoma (RCC). However, given the dynamic nature of skeletal muscle associated with malignancy, there is a need to evaluate the prognostic benefit of muscle area change from the preoperative to postoperative period. We hypothesize that an improvement in muscle area following nephrectomy, measured by linear segmentation of L3 psoas and paraspinal musculature, is associated with improvement in overall survival (OS) and cancer specific survival (CSS) for patients with pT3 and pT4 RCC.MethodsWe retrospectively analysed 270 pT3 and pT4 RCC patients who underwent nephrectomy from March 2004 to February 2020 with available preoperative and postoperative axial CT or MRI studies segmented at the L3 vertebrae. The majority were N0 (79%) and M0 (68%). Psoas and paraspinal muscles were measured bilaterally using a validated digital ruler tool. Total muscle area (TMA) was calculated by aggregating the area of all four muscles and total muscle area index (TMI) by dividing the TMA by height squared (m2). The prognostic value of postoperative muscle improvement, defined as any increase in muscle area index, was analysed using Kaplan–Meier and Cox proportional stepwise hazard models.ResultsMedian time between preoperative scans and surgery was approximately 22 days and between surgery and postoperative scans 172 days. One hundred twenty‐one patients (44.8%) had an increase in total muscle area index post‐nephrectomy (IQR = 33.4; P ≤ 0.0001). On Kaplan–Meier analysis, postoperative improvement in TMI was associated with decreased odds of mortality (P = 0.0024) with a median follow‐up of 38.6 months. In a multivariable Cox regression analysis, improvement of TMI was associated with increased OS (HR = 0.52, 95% CI 0.35–0.78, P < 0.001) and increased CSS (HR = 0.55, 95% CI 0.32–0.94, P = 0.030). A 5% or more improvement in TMI was also associated with increased OS (HR = 0.53, 95% CI 0.34–0.84, P = 0.006) and increased CSS (HR = 0.46, 95% CI 0.24–0.86, P = 0.015).ConclusionsAny improvement in TMI between preoperative and initial postoperative imaging after nephrectomy was associated with increased OS and CSS in patients with pT3 and pT4 RCC. Perioperative linear segmentation is an efficient tool that may improve current prognostication methods and can be performed on any imaging software platform.

This study compared the effects of cold water immersion (CWI) and hot water immersion (HWI) on muscle recovery following a muscle-damaging exercise protocol in women. Thirty healthy women (23.3 ± 2.9 years) were randomly assigned to either the CWI, HWI, or control (CON) groups. Participants completed a standardised exercise protocol (5 x 20 drop-jumps), followed by a 10 min recovery intervention (CWI, HWI, or CON) immediately and 120 min post-exercise. Physiological responses, including muscle oxygen saturation (SmO 2 ), core and skin temperature, and heart rate, were assessed at baseline, immediately post-exercise, after the first recovery intervention (postInt), and during 30 min follow-up. Recovery was evaluated through maximal voluntary isometric contraction, muscle swelling, muscle soreness ratings, and serum creatine kinase at baseline, 24, 48, and 72 h post-exercise. A mixed-effects model was used to account for repeated measures over time. Results showed lower SmO 2 values in the CWI compared to the HWI group at 20 min (Δ-6.76%, CI: −0.27 to −13.25, p = 0.038) and 30 min (Δ-9.86%, CI: −3.37 to −16.35, p = 0.001), and compared to CON at 30 min (Δ-7.28%, CI: −13.77 to −0.79, p = 0.022). Core temperature was significantly higher in the HWI than the CWI group (postInt and 30 min), while it was significantly lower in the CWI group than CON (30 min). CWI caused a substantial decrease in skin temperature compared to HWI and CON between postInt and 30 min follow-up (all p < 0.001). Skin temperature was higher in the HWI group compared to CON at postInt and throughout 30 min follow-up (all p < 0.001). No significant differences in recovery markers were observed between CWI and HWI groups, although HWI led to slightly higher creatine kinase levels (24 h and 72 h) and greater muscle swelling (24 h) compared to CON. Despite distinct acute physiological responses to CWI and HWI, neither improved subjective or objective recovery outcomes during the 72 h follow-up compared to CON in women following a muscle-damaging exercise protocol.

The essential amino acid leucine (LEU) plays a crucial role in promoting resistance-training adaptations. Dileucine (DILEU), a LEU-LEU dipeptide, increases MPS rates, however its impact on resistance training outcomes remains unexplored. This study assessed the effects of DILEU supplementation on resistance training adaptations. Using a randomized, double-blind, placebo-controlled approach, 34 resistance-trained males (age: 28.3 ± 5.9 years) consumed 2 grams of either DILEU monohydrate (RAMPS™, Ingenious Ingredients, L.P.), LEU, or placebo (PLA) while following a 4-day per week resistance training program for 10 weeks. Changes in body composition, 1-repetition maximum (1RM) and repetitions to failure (RTF) for leg press (LP) and bench press (BP), anaerobic capacity, countermovement jump (CMJ), and maximal voluntary contraction (MVC) were assessed after 0 and 10 weeks. Significant main effects for time (p < 0.001) were realized for LP and BP 1RM and RTF. A significant group × time interaction was identified for changes in LP 1RM (p = 0.02) and LP RTF (p = 0.03). Greater increases in LP 1RM were observed in DILEU compared to PLA (p = 0.02; 95% CI: 5.8, 73.2 kg), and greater increases in LP RTF in DILEU compared to LEU (p = 0.04; 95% CI: 0.58, 20.3 reps). No significant differences were found in other measures. DILEU supplementation at 2 grams daily enhanced lower body strength and muscular endurance in resistance-trained males more effectively than LEU or PLA. These findings suggest DILEU as a potentially effective supplement for improving adaptations to resistance training. NCT06121869 retrospectively registered.

Skeletal muscle fibers have a unique capacity to adjust their metabolism and phenotype in response to alternations in mechanical loading. Indeed, chronic mechanical loading leads to an increase in skeletal muscle mass, while prolonged mechanical unloading results in a significant decrease in muscle mass (muscle atrophy). The maintenance of skeletal muscle mass is dependent on the balance between rates of muscle protein synthesis and breakdown. While molecular mechanisms regulating protein synthesis during mechanical unloading have been relatively well studied, signaling events implicated in protein turnover during skeletal muscle recovery from unloading are poorly defined. A better understanding of the molecular events that underpin muscle mass recovery following disuse-induced atrophy is of significant importance for both clinical and space medicine. This review focuses on the molecular mechanisms that may be involved in the activation of protein synthesis and subsequent restoration of muscle mass after a period of mechanical unloading. In addition, the efficiency of strategies proposed to improve muscle protein gain during recovery is also discussed.

Background/Objectives: In this study, we aimed to examine the effect of creatine monohydrate (CrM) supplementation on recovery from eccentric exercise-induced muscle damage (EIMD) in diverse populations, including different sexes and age groups. EIMD decreases maximal voluntary contraction (MVC), restricts the range of motion (ROM), and increases muscle stiffness and delayed-onset muscle soreness, all of which negatively impact athletic performance. Therefore, developing effective recovery strategies is essential. Methods: A double-blind, randomized, placebo-controlled trial was conducted with 40 healthy male and female participants. After 33 days of supplementation with either CrM or placebo (crystalline cellulose), the participants performed eccentric exercises. Recovery indices, including MVC, muscle stiffness, subjective muscle extensive soreness, fatigue, and upper arm circumference, were measured at baseline, immediately after exercise, 48 h post-exercise, and 96 h post-exercise. Results: The creatine supplementation group (CRE) demonstrated a significantly quicker recovery of MVC than the placebo group (PLA). Furthermore, reductions in shear modulus and muscle fatigue were observed in the CRE group. Notably, females in the CRE group exhibited a significant suppression of post-exercise edema, suggesting a sex-specific response. Conclusions: These findings indicate that CrM supplementation may enhance recovery from EIMD, contributing to the maintenance of muscle function and the reduction of discomfort after exercise. CrM has the potential to serve as a practical nutritional strategy to promote recovery, not only for athletes, but also for a broader population.