Voluntary Wheel Running Exercise Improves Aging-Induced Sarcopenia via Activation of Peroxisome Proliferator-Activated Receptor Gamma Coactivator-1α/Fibronectin Type III Domain-Containing Protein 5/Adenosine Monophosphate-Activated Protein Kinase Signaling Pathway

Rodent model intervention for prevention and optimal management of sarcopenia: A systematic review on the beneficial effects of nutrients & non-nutrients and exercise to improve skeletal muscle health

Sarcopenia is a common musculoskeletal disorder characterized by degenerative processes and is strongly linked to an increased susceptibility to falls, fractures, physical limitations, and mortality. Several models have been used to explore therapeutic and preventative measures as well as to gain insight into the molecular mechanisms behind sarcopenia. With novel experimental methodologies emerging to design foods or novel versions of conventional foods, understanding the impact of nutrition on the prevention and management of sarcopenia has become important. This review provides a thorough assessment of the use of rodent models of sarcopenia for understanding the aging process, focusing the effects of nutrients, plant extracts, exercise, and combined interventions on skeletal muscle health. According to empirical research, nutraceuticals and functional foods have demonstrated potential benefits in enhancing physical performance. In preclinical investigations, the administration of herbal extracts and naturally occurring bioactive compounds yielded advantageous outcomes such as augmented muscle mass and strength generation. Furthermore, herbal treatments exhibited inhibitory effects on muscle atrophy and sarcopenia. A substantial body of information establishes a connection between diet and the muscle mass, strength, and functionality of older individuals. This suggests that nutrition has a major impact in both the prevention and treatment of sarcopenia.

Biomarkers of frailty

Several biomarkers have been proposed to identify frailty, a multisystemic age-related syndrome. However, the complex pathophysiology and the absence of a consensus on a comprehensive and universal definition make it challenging to pinpoint a singular biomarker or set of biomarkers that conclusively characterize frailty. This review delves into the main laboratory biomarkers, placing special emphasis on those associated with various pathways closely tied to the frailty condition, such as inflammation, oxidative stress, mitochondrial dysfunction, metabolic and endocrine alterations and microRNA. Additionally, we provide a summary of different clinical biomarkers encompassing different tools that have been proposed to assess frailty. We further address various imaging biomarkers such as Dual Energy X-ray Absorptiometry, Bioelectrical Impedance analysis, Computed Tomography and Magnetic Resonance Imaging, Ultrasound and D3 Creatine dilution. Intervention to treat frailty, including non-pharmacological ones, especially those involving physical exercise and nutrition, and pharmacological interventions, that include those targeting specific mechanisms such as myostatin inhibitors, insulin sensitizer metformin and with special relevance for hormonal treatments are mentioned. We further address the levels of different biomarkers in monitoring the potential positive effects of some of these interventions. Despite the availability of numerous biomarkers, their performance and usefulness in the clinical arena are far from being satisfactory. Considering the multicausality of frailty, there is an increasing need to assess the role of sets of biomarkers and the combination between laboratory, clinical and image biomarkers, in terms of sensitivity, specificity and predictive values for the diagnosis and prognosis of the different outcomes of frailty to improve detection and monitoring of older people with frailty or at risk of developing it, being this a need in the everyday clinical practice.

Highlighting the effect of reduced training volume on maintaining hormonal adaptations obtained from periodized resistance training in sarcopenic older women

BACKGROUND

This study investigated the impact of the High Intensity Interval Resistance Training (HIIRT) protocol on hormonal changes in older women.

RESEARCH DESIGN AND METHODS

Forty sarcopenic women were divided into an experimental group (EX = 30) and a control group (C = 10). The EX-group was further divided into Maintenance Training 1 (MT1 = 10), Maintenance Training 2 (MT2 = 10), and Detraining (DT = 10). The participants underwent 8 weeks of resistance training, consisting of hypertrophy and strength cycles. Following this, the EX-group had a 4-week period with no exercise or a reduced training volume. Measurements were taken at three time points.

RESULTS

After 8 weeks, the EX-group showed significant improvements in Insulin Like Growth Factor-1 (IGF-1), Myostatin (MSTN), Follistatin (Fstn), Growth Hormone (GH) and Cortisol (Cort) compared to the control group. During the volume reduction period, there were no significant differences between MT1 and MT2 groups, but both groups saw increases in IGF-1, Fstn, GH, and decreases in MSTN and Cort compared to the DT group.

CONCLUSIONS

These findings suggest that performing at least one training session per week with the HIIRT protocol is crucial for maintaining hormonal adaptations in sarcopenic older women.

Exercise and mitochondrial mechanisms in patients with sarcopenia

Sarcopenia is a severe loss of muscle mass and functional decline during aging that can lead to reduced quality of life, limited patient independence, and increased risk of falls. The causes of sarcopenia include inactivity, oxidant production, reduction of antioxidant defense, disruption of mitochondrial activity, disruption of mitophagy, and change in mitochondrial biogenesis. There is evidence that mitochondrial dysfunction is an important cause of sarcopenia. Oxidative stress and reduction of antioxidant defenses in mitochondria form a vicious cycle that leads to the intensification of mitochondrial separation, suppression of mitochondrial fusion/fission, inhibition of electron transport chain, reduction of ATP production, an increase of mitochondrial DNA damage, and mitochondrial biogenesis disorder. On the other hand, exercise adds to the healthy mitochondrial network by increasing markers of mitochondrial fusion and fission, and transforms defective mitochondria into efficient mitochondria. Sarcopenia also leads to a decrease in mitochondrial dynamics, mitophagy markers, and mitochondrial network efficiency by increasing the level of ROS and apoptosis. In contrast, exercise increases mitochondrial biogenesis by activating genes affected by PGC1-ɑ (such as CaMK, AMPK, MAPKs) and altering cellular calcium, ATP-AMP ratio, and cellular stress. Activation of PGC1-ɑ also regulates transcription factors (such as TFAM, MEFs, and NRFs) and leads to the formation of new mitochondrial networks. Hence, moderate-intensity exercise can be used as a non-invasive treatment for sarcopenia by activating pathways that regulate the mitochondrial network in skeletal muscle.

Resistance Exercise Improves Spatial Learning Ability Through Phosphorylation of 5'-Adenosine Monophosphate-Activated Protein Kinase in Parkinson Disease Mice

Purpose

Exercise is a representative noninvasive treatment that can be applied to various diseases. We studied the effect of resistance exercise on motor function and spatial learning ability in Parkinson disease (PD) mice.

Methods

The rotarod test and beam walking test were conducted to evaluate the effect of resistance exercise on motor function, and the Morris water maze test was conducted to examine the effect of resistance exercise on spatial learning ability. The effect of resistance exercise on brain-derived neurotrophic factor (BDNF) and tropomyosin receptor kinase B (TrkB) expression and 5’-adenosine monophosphate-activated protein kinase (AMPK) phosphorylation was investigated by Western blot analysis. New cell generation was confirmed by immunohistochemistry for 5-bromo-2’-deoxyuridine.

Results

Resistance exercise improved coordination, balance, and spatial learning ability in PD mice. Resistance exercise enhanced new cell production, BDNF and TrkB expression, and AMPK phosphorylation in PD mice. The effect of such resistance exercise was similar to that of levodopa application.

Conclusions

In PD-induced mice, resistance exercise enhanced AMPK phosphorylation to increase BDNF expression and new neuron generation, thereby improving spatial learning ability. Resistance exercise is believed to help improve symptoms of PD.