Multifactorial Mechanism of Sarcopenia and Sarcopenic Obesity. Role of Physical Exercise, Microbiota and Myokines

Obesity and ageing place a tremendous strain on the global healthcare system. Age-related sarcopenia is characterized by decreased muscular strength, decreased muscle quantity, quality, and decreased functional performance. Sarcopenic obesity (SO) is a condition that combines sarcopenia and obesity and has a substantial influence on the older adults’ health. Because of the complicated pathophysiology, there are disagreements and challenges in identifying and diagnosing SO. Recently, it has become clear that dysbiosis may play a role in the onset and progression of sarcopenia and SO. Skeletal muscle secretes myokines during contraction, which play an important role in controlling muscle growth, function, and metabolic balance. Myokine dysfunction can cause and aggravate obesity, sarcopenia, and SO. The only ways to prevent and slow the progression of sarcopenia, particularly sarcopenic obesity, are physical activity and correct nutritional support. While exercise cannot completely prevent sarcopenia and age-related loss in muscular function, it can certainly delay development and slow down the rate of sarcopenia. The purpose of this review was to discuss potential pathways to muscle deterioration in obese individuals. We also want to present the current understanding of the role of various factors, including microbiota and myokines, in the process of sarcopenia and SO.

Effects of a Web-based Intervention on Cardiovascular and Physical Health of Korean Older Adults During the Pandemic

During the lockdown, 97.5% of Korean senior centers in South Korea were closed to prevent the spread of the coronavirus disease 2019 (COVID-19). The threat of the COVID-19 presented the need for alternative interventions for Korean older adults to maintain cardiovascular and physical health. Korean senior centers implemented web-based interventions to provide physical health services, but their effectiveness was not yet assessed. Thus, our study aimed to identify the effects of a web-based intervention using a smartwatch and mobile app in older adults when compared to center-based intervention during the pandemic. This study collected 117 Korean older adults (≥ 60) who participated in the 12-week web-based and center-based physical interventions using a smartwatch and mobile app. This quasi-experimental study was conducted between August and December in 2020. We analyzed the pre-posttest of cardiovascular and physical health across two intervention types. Our regression results indicated that participants in the 12-week web-based intervention reported better cardiovascular (systolic blood pressure: b = -13.77, p < .001; cholesterol: b = -11.71, p < .05) and physical health (muscular function: b = 2.99, p < .001; body balance: b = -1.31, p < .001; cardiopulmonary endurance: b = 33.33, p < .001) than those in center-based intervention at posttest. The findings imply a web-based intervention is likely to become an innovative therapeutic strategy for older adults' health to respond to the rapidly changing social service systems amid the pandemic.

Volumetric MRI is a promising outcome measure of muscle reinnervation

The development of outcome measures that can track the recovery of reinnervated muscle would benefit the clinical investigation of new therapies which hope to enhance peripheral nerve repair. The primary objective of this study was to assess the validity of volumetric Magnetic Resonance Imaging (MRI) as an outcome measure of muscle reinnervation by testing its reproducibility, responsiveness and relationship with clinical indices of muscular function. Over a 3-year period 25 patients who underwent nerve transfer to reinnervate elbow flexor muscles were assessed using intramuscular electromyography (EMG) and MRI (median post-operative assessment time of 258 days, ranging from 86 days pre-operatively to 1698 days post- operatively). Muscle power (Medical Research Council (MRC) grade) and Stanmore Percentage of Normal Elbow Assessment (SPONEA) assessment was also recorded for all patients. Sub-analysis of peak volitional force (PVF), muscular fatigue and co-contraction was performed in those patients with MRC > 3. The responsiveness of each parameter was compared using Pearson or Spearman correlation. A Hierarchical Gaussian Process (HGP) was implemented to determine the ability of volumetric MRI measurements to predict the recovery of muscular function. Reinnervated muscle volume per unit Body Mass Index (BMI) demonstrated good responsiveness (R2 = 0.73, p < 0.001). Using the temporal and muscle volume per unit BMI data, a HGP model was able to predict MRC grade and SPONEA with a mean absolute error (MAE) of 0.73 and 1.7 respectively. Muscle volume per unit BMI demonstrated moderate to good positive correlations with patient reported impairments of reinnervated muscle; co- contraction (R2 = 0.63, p = 0.02) and muscle fatigue (R2 = 0.64, p = 0.04). In summary, volumetric MRI analysis of reinnervated muscle is highly reproducible, responsive to post-operative time and demonstrates correlation with clinical indices of muscle function. This encourages the view that volumetric MRI is a promising outcome measure for muscle reinnervation which will drive advancements in motor recovery therapy.

A rare but treatable inborn error of metabolism: Arginine glycine amidinotransferase (AGAT) deficiency

AGAT deficiency is a rare and treatable autosomal recessive disorder. The symptoms are early-onset developmental mild to moderate intellectual disability, delayed speech acquisition, behavioral problems or proximal muscle weakness. Biochemical screening for creatine, creatinine and urinary guanidinoacetate and genetic tests are used for diagnosis. Electromyography may be normal or may have a myopathic pattern with low amplitude polyphasic waves. Muscle biopsy may show abnormalities including small myocytes. Creatine supplementation can fully prevent the neurological disability, if the treatment is started early in life; the muscular function improves irrespective of the supplementation moment.