Effects of protein supplementation in older adults undergoing resistance training: a systematic review and meta-analysis.

BACKGROUND: Older individuals present reductions in muscle mass and physical function, as well as a blunted muscle protein synthesis response to amino acid administration and physical activity. Although resistance training is an effective intervention to slow down muscle impairments in the elderly, there is no consensus whether a combination with protein supplementation could offer additional benefits to an older population. OBJECTIVE: We aimed to systematically summarize and quantify whether protein supplementation could optimize the effects of resistance training on muscle mass and strength in an aged population. DESIGN: A structured literature search was conducted on MEDLINE (PubMed), Cochrane, EMBASE and LILACS databases. The search had no period or language restrictions. Inclusion criteria comprised study design (randomized controlled trials-RCTs), sample mean age (60 years and over) and intervention (a resistance training program for a period of 6 weeks or longer combined with protein or amino acids supplementation). Two independent reviewers performed the study selection and data extraction. Continuous data on fat-free mass, muscle mass and muscle strength were pooled using a random-effects model. RESULTS: Of the 540 articles reviewed, 29 eligible articles underwent full-text evaluation. Nine RCTs (462 subjects) met the inclusion criteria and were included in the study. The mean age of the participants ranged from 61 to 79 years old. Protein supplementation protocols varied widely throughout the studies. Three studies used quantities related to the body mass of the participants and the other six trials provided supplements in daily amounts, independently of subjects' body masses. Overall, protein supplementation in combination with resistance training was associated with gains in fat-free mass, resulting in a standardized mean difference (SMD) of 0.23 [95% confidence interval (CI), 0.05-0.42]. However, protein supplementation was not associated with changes in muscle mass (0.14, 95% CI -0.05 to 0.32) or muscle strength (0.13, 95% CI -0.06 to 0.32). LIMITATIONS: Studies among the very elderly population are scarce. The variation regarding the supplementation protocol, namely the different protein sources, amounts and timing of ingestion, also made it harder to compare the results. The general quality of the studies was low, reflecting increased risk of bias in some studies. Despite these limitations, this systematic review provides a general overview of the role of protein supplementation with no other added macronutrients to augment muscle mass and strength during resistance training in older adults. CONCLUSION: Combining protein supplementation with resistance training is effective for eliciting gains in fat-free mass among older adults, but does not seem to increase muscle mass or strength.

Echo intensity is negatively associated with functional capacity in older women.

Muscle quality is an important component of the functional profile of the elderly, and previous studies have shown that both muscle quantity and quality independently contribute to muscle strength of the elderly. This study aimed to verify the association between quadriceps femoris muscle quality, analyzed by specific tension and echo intensity (EI), and rate of torque development (RTD) of the knee extensor muscles with the functional performance in elderly active women. Forty-five healthy, active elderly women (70.28 ± 6.2) volunteered to participate in this study. Quadriceps femoris muscle thickness and EI were determined by ultrasonography. Knee extension isometric peak torque and RTD were obtained from maximal isometric voluntary contraction curves. The 30-s sit-to-stand-up (30SS) test and usual gait speed (UGS) test were applied to evaluate functional performance. Rectus femoris EI presented a significant negative correlation with 30SS (r = -0.505, P < 0.01), UGS (r s = -0.347, P < 0.05), and isometric peak torque (r = -0.314, P < 0.05). The quadriceps femoris EI correlated negatively with 30SS (r = -0.493, P < 0.01) and isometric peak torque (r = -0.409, P < 0.01). The EI of the quadriceps femoris and all quadriceps muscle portions significantly correlated with RTD. RTD significantly correlated with physical performance in both functional tests (30SS = r = 0.340, P < 0.05; UGS = r s = 0.371, P < 0.05). We concluded that muscle EI may be an important predictor of functional performance and knee extensor power capacity in elderly, active women.

Strength training prior to endurance exercise: impact on the neuromuscular system, endurance performance and cardiorespiratory responses.

This study aimed to investigate the acute effects of two strength-training protocols on the neuromuscular and cardiorespiratory responses during endurance exercise. Thirteen young males (23.2 ± 1.6 years old) participated in this study. The hypertrophic strength-training protocol was composed of 6 sets of 8 squats at 75% of maximal dynamic strength. The plyometric strength-training protocol was composed of 6 sets of 8 jumps performed with the body weight as the workload. Endurance exercise was performed on a cycle ergometer at a power corresponding to the second ventilatory threshold until exhaustion. Before and after each protocol, a maximal voluntary contraction was performed, and the rate of force development and electromyographic parameters were assessed. After the hypertrophic strength-training and plyometric strength-training protocol, significant decreases were observed in the maximal voluntary contraction and rate of force development, whereas no changes were observed in the electromyographic parameters. Oxygen uptake and a heart rate during endurance exercise were not significantly different among the protocols. However, the time-to-exhaustion was significantly higher during endurance exercise alone than when performed after hypertrophic strength-training or plyometric strength-training (p <0.05). These results suggest that endurance performance may be impaired when preceded by strength-training, with no oxygen uptake or heart rate changes during the exercise.

Disordered eating behaviors and body image in male athletes.

OBJECTIVE: To identify disordered eating behaviors and body image dissatisfaction, as well as their relationship to body fat (BF), among male athletes in high risk sports for eating disorders. METHODS: One hundred and fifty-six male athletes were divided into the following categories: weight-class sports, sports where leanness improves performance, and sports with aesthetic ideals. BF was assessed and three questionnaires were used: the Eating Attitudes Test; the Bulimic Investigatory Test, Edinburgh; the Body Shape Questionnaire. RESULTS: Disordered eating behaviors and body image dissatisfaction were found in 43 (27.6%) and 23 athletes (14.7%), respectively, and an association was detected between the two variables (p < 0.001). Athletes with and without disordered eating behaviors did not differ in %BF (11.0 ± 5.2% and 9.8 ± 4.0%, respectively; p = 0.106). However, athletes with body image dissatisfaction had higher %BF than those who were satisfied (12.6 ± 5.9% and 9.7 ± 3.9%, respectively; p = 0.034). There were no differences in BF, frequency of disordered eating behaviors, and body image dissatisfaction between sports categories. CONCLUSION: Nearly one-quarter of athletes showed disordered eating behaviors, which was associated with body image dissatisfaction. Athletes with higher %BF were more likely to be dissatisfied with body image. There was no difference in eating behavior and body image between athletes from different sports categories.

Disordered eating behaviors and body image in male athletes

Objective: To identify disordered eating behaviors and body image dissatisfaction, as well as their relationship to body fat (BF), among male athletes in high risk sports for eating disorders. Methods: One hundred and fifty-six male athletes were divided into the following categories: weight-class sports, sports where leanness improves performance, and sports with aesthetic ideals. BF was assessed and three questionnaires were used: the Eating Attitudes Test; the Bulimic Investigatory Test, Edinburgh; the Body Shape Questionnaire. Results: Disordered eating behaviors and body image dissatisfaction were found in 43 (27.6%) and 23 athletes (14.7%), respectively, and an association was detected between the two variables (p < 0.001). Athletes with and without disordered eating behaviors did not differ in %BF (11.0±5.2% and 9.8±4.0%, respectively; p = 0.106). However, athletes with body image dissatisfaction had higher %BF than those who were satisfied (12.6±5.9% and 9.7±3.9%, respectively; p = 0.034). There were no differences in BF, frequency of disordered eating behaviors, and body image dissatisfaction between sports categories. Conclusion: Nearly one-quarter of athletes showed disordered eating behaviors, which was associated with body image dissatisfaction. Athletes with higher %BF were more likely to be dissatisfied with body image. There was no difference in eating behavior and body image between athletes from different sports categories. .