Diabetes mellitus induces a reduction in skeletal muscle mass and strength. Strength training is prescribed as part of treatment since it improves glycemic control and promotes increase of skeletal muscle mass. The mechanisms involved in overload-induced muscle hypertrophy elicited at the establishment of the type I diabetic state was investigated in Wistar rats. The purpose was to examine whether the overload-induced hypertrophy can counteract the hypotrophy associated to the diabetic state. The experiments were performed in oxidative (soleus) or glycolytic (EDL) muscles. PI3K/Akt/mTOR protein synthesis pathway was evaluated 7 days after overload-induced hypertrophy of soleus and of EDL muscles. The mRNA expression of genes associated with different signaling pathways that control muscle hypertrophy was also evaluated: mechanotransduction (FAK), Wnt/β-catenin, myostatin, and follistatin. The soleus and EDL muscles when submitted to overload had similar hypertrophic responses in control and diabetic animals. The increase of absolute and specific twitch and tetanic forces had the same magnitude as muscle hypertrophic response. Hypertrophy of the EDL muscle from diabetic animals mostly involved mechanical loading-stimulated PI3K/Akt/mTOR pathway besides the reduced activation of AMP-activated protein kinase (AMPK) and decrease of myostatin expression. Hypertrophy was more pronounced in the soleus muscle of diabetic animals due to a more potent activation of rpS6 and increased mRNA expression of insulin-like growth factor-1 (IGF-1), mechano-growth factor (MGF) and follistatin, and decrease of myostatin, MuRF-1 and atrogin-1 contents. The signaling changes enabled the soleus muscle mass and force of the diabetic rats to reach the values of the control group.

We determined the prevalence of metabolic syndrome (MetS) among military police officers (MPOs) from the radio patrol program of the Military Police of Sao Paulo State (PMESP). Towards this goal, we analyzed the following characteristics: shift duty (daytime or nighttime patrol), service length in the PMESP, education level attained, weekly alcohol consumption, smoking, and physical activity of 93 MPOs. The MPO groups were created based on work shift [daytime (n=48) or nighttime (n=45)], and years of MPO experience [≤3 years (n=48) or ≥10 years (n=45)]. The overall prevalence of MetS among the 93 MPOs was 43%. There was a higher prevalence of MetS in the group with ≥ten years (53.3%) than that with ≤three years (33.3%); so, 1,6 times higher. The more prevalent MetS indicators (n=93) included waist circumference (76.3%), hypertension (55.9%), reduced plasma HDL-cholesterol levels (44%), hypertriglyceridemia (32.2%), and hyperglycemia (20.4%). Greater waist circumference, hypertension, hypertriglyceridemia, higher glycated hemoglobin A1c (HbA1c) levels, and MetS itself were associated with the service length (i.e., ≥ten years). The work shift was not associated with any MetS indicator. Those who were overweight or obese were 2.2. times more likely to develop MetS. Hypertriglyceridemia, the best indicator of the MetS, increased the chance of developing MetS by 16 times. Conclusion: MPOs exhibit a high prevalence of MetS, associated with the years of service and age.

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Skeletal muscle electrical stimulation is commonly used for clinical purposes, assisting recovery, preservation, or even improvement of muscle mass and function in healthy and pathological conditions. Additionally, it is a useful research tool for evaluation of skeletal muscle contractile function. It may be applied in vitro, using cell culture or isolated fibers/muscles, and in vivo, using human subjects or animal models (neuromuscular electrical stimulation - NMES). This chapter focuses on the electrical stimulation of the sciatic nerve as a research method for evaluation of the contractile properties of murine hind limb muscles. Variations of this protocol allow for the assessment of muscle force, fatigue resistance, contraction and relaxation times, and can be used as a model of contraction-induced muscle injury, reactive oxygen species production, and muscle adaptation to contractile activity.

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