Influence of resistance training on muscle architecture in older adults: A systematic review and meta-analysis of randomized controlled trials.

BACKGROUND: Resistance training (RT) consists of planned exercise programs to increase muscle strength capacity through neural and structural adaptations, such as changes in the geometric arrangement of muscle fibers. This study aimed to analyze the influence of RT on muscle architecture in older people. METHODS: This PROSPERO-registered systematic review and meta-analysis (identification number CRD42022340477) followed the PRISMA guidelines. Four electronic databases were searched for eligible randomized controlled trials (RCTs) that observed older individuals submitted to RT programs that reported muscle architecture outcomes. RESULTS: Seventeen RCTs met the eligibility criteria with a total of 488 participants. The main results of the meta-analysis showed that RT interventions had a significant effect on the thickness of the medial gastrocnemius (SMD = 0.12; 95% CI: - 0.07 to 0.17; p < 0.00001; I2 = 0%). CONCLUSION: Based on available evidence, studies included in this review showed improvement in maximum isometric force, pennation angle, fascicle length, thickness, and muscle activation after RT interventions. In turn, the meta-analysis suggested a potential for improving the thickness of the medial gastrocnemius after the intervention. However, any clinical implications drawn from the analyses should be interpreted with caution, as these findings are substantially limited due to a low number of included studies and a potential heterogeneity between studies.

Correlation between pain, anthropometric measurements, stress and biochemical markers in women with low back pain.

Aim: To analyze the associations between pain duration, pain levels, anthropometric measures, perceived stress and biochemical markers in women with low back pain. Materials & methods: Forty-two participants were submitted to body mass, height, abdominal circumference, cortisol and creatine kinase (CK) collections. Pain duration, pain levels and stress were analyzed through specific questionnaires. Results: There were positive correlations between abdominal circumference and body mass, duration of pain and age, abdominal circumference, CK and age, CK and BMI, CK and abdominal circumference, and CK and duration of pain (p < 0.05). Conclusion: The higher the level of tissue damage over the years, the greater the tendency for higher levels of low back pain perception. Central fat was related to greater load on the spine.

Lay abstract Low back pain (LBP) is one of the factors that hinders the routine and productivity of women. LBP can cause functional disability and negatively interfere with work activities. The increase in pain can be caused by mechanical postural factors (such as behavioral habits), traumatic (such as accidents), and psychosocial factors (such as physical inactivity). Chronic LBP can influence behavioral aspects due to adaptations of pain feedback, such as postures to avoid pain and sedentary lifestyle. In this study, we observed that duration of LBP was related to higher levels of creatine kinase, which is an enzyme of our body that can be related to tissue damage. Moreover, the abdominal circumference, due to the accumulation of fat in this region, presented correlation with higher levels of tissue damage by creatine kinase and longer exposure time with LBP.

Effects of physical exercise on low back pain and cortisol levels: a systematic review with meta-analysis of randomized controlled trials.

Aim: To verify the effects of physical exercise on low back pain (LBP) and serum cortisol levels in individuals with chronic LBP. Materials & methods: Randomized controlled trials evaluating the effects of exercise on LBP perception and cortisol levels in adults with nonspecific chronic LBP were included. Results: Four randomized controlled trials were included, with a total of 85 participants in the exercise group and 84 in the control group. The interventions reduced -1.61 (95% CI: -2.36 to -0.85) with inconsistency I2 = 72% (p = 0.031) the LBP level and increased 1.05 (95% CI: 0.22-2.32) with inconsistency I2 = 86% (p < 0.0001) the cortisol levels. Conclusion: The practice of physical exercise for 6 weeks or more reduced LBP levels, whereas the rate of progression of an exercise-training program in people with chronic LBP is greater than 4 weeks, but increased the cortisol serum levels in individuals with LBP.