Muscles

This study compared elbow flexor hypertrophy and maximal strength adaptations after eight weeks of resistance training performed either to momentary muscular failure or with 1–3 repetitions in reserve (RIR). Nineteen resistance-trained adults completed a unilateral within-participant protocol in which one arm trained to failure and the contralateral arm trained with 1–3 RIR. Participants trained twice weekly using the unilateral preacher curl exercise at 70–80% one-repetition maximum (1RM). Elbow flexor muscle thickness and 1RM strength were assessed before and after the intervention. Bayesian mixed-effects models estimated between-condition differences. Both protocols increased muscle thickness and 1RM strength. The estimated between-condition differences for muscle thickness were 0.032 cm (95% highest density interval [HDI]: −0.044 to 0.113) while the estimated difference in 1RM strength was 0.588 kg (85% HDI: −0.491 to 1.66), with both 95% HDIs spanning zero and including values favoring either protocol. Sex-specific analyses showed the same general patter of responses. Overall, resistance training performed with 1–3 RIR produces similar elbow flexor hypertrophy and maximal strength adaptations to training performed to momentary muscular failures under the loading and volume conditions examined.

Primary dystrophin deficiency, caused by X-chromosome mutations within the DMD gene, encompasses a continuous clinical spectrum of neurological, muscular, and cardiac disorders known as dystrophinopathies that exhibit profound phenotypic variability driven by specific mutation profiles and epigenetic factors. This comprehensive review analyzes the clinical and molecular characteristics of seven primary classifications: Duchenne muscular dystrophy (DMD), a severe childhood myopathy caused by a complete absence of the protein that leads to loss of ambulation and fatal cardiorespiratory failure in youth; Becker muscular dystrophy (BMD), a milder variant with partial protein deficiency that preserves walking capabilities into adulthood and prolongs life expectancy; pseudometabolic dystrophinopathic syndrome, featuring exercise intolerance, cramps, and recurrent rhabdomyolysis that mimics metabolic diseases; asymptomatic dystrophinopathy, representing the mild end of the spectrum identified incidentally through chronically elevated creatine kinase levels; brain dystrophin-related syndrome, where the disruption of distal isoforms like Dp140 and Dp71 results in neurodevelopmental and neuropsychiatric comorbidities such as ADHD, autism, and intellectual disability; X-linked dilated cardiomyopathy (XLDCM), a cardiac-selective condition causing severe heart failure and arrhythmias while sparing skeletal muscle function; and female dystrophin-related syndrome, distinguishing between familial carriers—who can manifest symptoms due to skewed X-chromosome inactivation—and rare sporadic females who develop an exceptional, severe, Duchenne-like phenotype due to cytogenetic accidents such as Turner syndrome or chromosomal translocations. Ultimately, advancements in molecular testing (NGS and WGS) have significantly optimized diagnostic precision, proving essential for implementing early cardioprotective care, accurate genetic counseling, and the development of future tissue-specific targeted gene therapies. The present study also discusses the psychosocial impact that the disease has on patients.

Charcot–Marie–Tooth (CMT) is a rare, genetic, slowly progressive disorder that affects nerve conduction, particularly in the limbs and, therefore, the muscles. Phenotypes vary, but the impact on quality of life is always present. CMT1A is the most prevalent type. There is no pharmacological cure, so physiotherapy is essential, but nutritional and exercise aspects are rarely considered. In this case report, we demonstrate how, even in this condition, effective results can be achieved with strength training if properly supervised, coordinated with physiotherapy, and combined with an appropriate nutritional plan.