Sarcopenia is a multifactorial process defined by loss of strength and skeletal muscle mass, which leads to a reduction in muscle cross-sectional area (CSA). Although resistance training (RT) has been indicated as a tool to counteract sarcopenia, the protein profile associated with skeletal muscle adaptations remains to be determined. We investigated the effects of 12 weeks of RT on the skeletal muscle proteome profile and CSA of young and older rats. Twenty-four animals were divided into four groups: young sedentary or trained and older sedentary or trained (six animals per group). A 12-week RT protocol was performed, which consisted of climbing a vertical ladder.The proteins from the gastrocnemius were analysed by LC-ESI-MS/MS. Onehundred and thirty-one proteins were identified, of which 28 were assessed between the groups. Ageing induced an increase in proteins associated with the glycolytic pathway, transport and stress response, which represent crucial mechanisms for muscle adaptation. RT upregulated metabolic enzymes, anti-oxidant activity and transport proteins, besides increasing hypertrophy, regardless of age, suggesting a beneficial adaptation to mitigate age-related sarcopenia. RT reduced muscle atrophy through the regulation of stress response and by increasing proteins related to energy production and transport, which in turn might protect tissue damage arising from exercise and ageing.Significance of the study: Protein abundance levels related to the metabolic process and stress response were increased in the aged muscle. RT proved to be an important intervention capable of inducing significant effects on muscle proteome regardless of ageing, due to upregulation of glycolytic enzymes, and anti-oxidant and transport proteins. This effect could lead to a beneficial adaptation in muscle structure, cellular function and overall homeostasis maintenance. This study contributes to better understanding of the basic biology of ageing and clarifies more profoundly the molecular networks behind physiological adaptations promoted by exercise training.ABBREVIATIONS: ENOB, beta-enolase; CAH3, carbonic anhydrase 3; KCRM, creatine kinase M-type; ALDOA, fructose-bisphosphate aldolase A; G3P, glyceraldehyde-3 phosphate dehydrogenase; G6PI, glucose-6-phosphate isomerase; HBA, haemoglobin subunit alpha-1/2; HBB1, haemoglobin subunit beta1; LDHA, L lactate dehydrogenase A chain; MYG, myoglobin; MYL1, myosin light chain 1/3; MLRS, myosin regulatory light chain 2; PRVA, parvalbumin alpha; KPYM, pyruvate kinase; PGM1, phosphoglucomutase 1; PGK1, phosphoglycerate kinase 1; PGAM2, phosphoglycerate mutase 2; TPIS, triosephosphate isomerase; PARK7, protein deglycase DJ 1; SODC, superoxide dismutase-Cu-Zn. † Both authors contributed equally.
Objective: The objective of this study was to verify the effects of resisted and proprioceptive exercises program for the treatment of patients diagnosed with patellofemoral pain syndrome (PFPS). Design method: Randomized Controlled Trial e level of evidence, II. Methods: Sixty female patients, clinically diagnosed with PFPS, were allocated into two experimental groups. The exercise group (ExG) underwent 6 weeks of a resisted and proprioceptive exercises for the trunk muscles, abductors and lateral hip rotators and knee extensors. The Guidance Group (GG) received educational, cognitive and behavioral guidance on healthcare. Before and after the program implementation period, all participants were evaluated in relation to the injured limb for pain assessment, subjective functionality, maximum isometric strength and 2D biomechanical analysis. Results: After a six-week follow-up, ExG showed significant improvement in the Numerical Pain Rating Scale, Anterior Knee Pain Scale and Knee Outcome Survey-Activities of Daily Living Scale when compared to the control group (p 0,05). The ExG also proved superior for increased muscle strength of knee extensors, hip abductors, decreased dynamic knee valgus and pelvic drop in relation to GG (p 0.05). However, when we consider the strength of the hip lateral rotator muscles there was no difference between the two interventions (p > 0.05). Conclusion:Resisted and proprioceptive exercises yielded superior results to those of a treatment focused on educational, cognitive and behavioral guidance in improving pain and lower limb function for women with PFPS.
Cross-talk between skeletal muscle and tendon is important for tissue homeostasis. Whereas the skeletal muscle response to tendon injury has been well-studied, to the best of our knowledge the tendon response to skeletal muscle injury has been neglected. Thus, we investigated calcaneal tendon extracellular matrix (ECM) remodeling after gastrocnemius muscle injury using a rat model. Wistar rats were randomly divided into four groups: control group (C; animals that were not exposed to muscle injury) and harvested at different time points post gastrocnemius muscle injury (3, 14, and 28 days) for gene expression, morphological, and biomechanical analyses. At 3 days post injury, we observed mRNA-level dysregulation of signaling pathways associated with collagen I accompanied with disrupted biomechanical properties. At 14 days post injury, we found reduced collagen content histologically accompanied by invasion of blood vessels into the tendon proper and an abundance of peritendinous sheath cells. Finally, at 28 days post injury, there were signs of recovery at the gene expression level including upregulation of transcription factors related to ECM synthesis, remodeling, and repair. At this time point, tendons also presented with increased peritendinous sheath cells, decreased adipose cells, higher Young’s modulus, and lower strain to failure compared to the uninjured controls and all post injury time points. In summary, we demonstrate that the calcaneal tendon undergoes extensive ECM remodeling in response to gastrocnemius muscle injury leading to altered functional properties in a rat model. Tendon plasticity in response to skeletal muscle injury merits further investigation to understand its physiological relevance and potential clinical implications.
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