Adjusting Grip Strength to Body Size: Analyses From 6 Countries.

OBJECTIVES: Absolute handgrip strength and adjusted by body mass index are useful to identify age-related conditions. However, these values are not accurate for older adults with extreme body size because of the nonlinear relationship between strength, height, and body mass. The purpose of this study was to determine cut-off points for age-related conditions of older adults using allometric coefficients to normalize grip strength by body size. DESIGN: Cross-sectional study. SETTING AND PARTICIPANTS: Data from 13,235 older adults of Study on Global Aging and Adult Health conducted in 6 low- and middle-income countries were analyzed. METHODS: Country- and sex-specific allometric exponents for body-size variables (mass and height) were computed with log-linear models. Partial correlation verified whether allometric normalization removed the effect of body size on grip strength. Cut-off points were established (<20th percentile) for low allometrically adjusted grip strength. RESULTS: Allometric exponents for normalization of grip strength were provided for body-size variables, ranging from 0.19 to 2.45. Allometric normalization removed the effect of body size on grip strength (r < 0.30). Overall, frequencies of low muscle strength were overestimated with international criteria (absolute grip strength) compared with the cut-off points proposed in this study. CONCLUSIONS AND IMPLICATIONS: The proposed allometric exponents normalized grip strength according to body-size variables. These exponents improved the accuracy in identifying age-related conditions in older adults with extreme body size. The variability between strength reveals the need for developing specific cut-off points for low- and middle-income countries. New cut-off points of low normalized grip strength with automatized applicability were proposed for health care providers use in clinical practice.

Resistance training with blood flow restriction: Impact on the muscle strength and body composition in people living with HIV/AIDS.

The aim of the study was to compare the impact of 12-week resistance training with blood flow restriction (GRTBFR) versus, traditional resistance training (GTRT) and non-training on the muscle strength and body composition HIV/AIDS participants. Muscle strength was tested at baseline, and on the 6th, 21st and 36th training sessions, using maximal repetition test. Pre- and post-intervention body composition changes were measured by dual-energy X-ray absorptiometry. Resistance training was undertaken three times a week comprising bilateral elbow extension and flexion exercises, unilateral flexion and bilateral knee extension. Changes in strength and body composition (pre- and post-intervention) between groups were evaluated by mixed models of repeated measures, and by paired and unpaired comparisons, considering the Effect Size. All groups were similar at baseline for muscle strength and body composition. Post-intervention, the training groups showed similar, statistically significant increases in muscle strength (GRTBFR=25.7-57.4%; GTRT=24.5-52.3%) and skeletal muscle tissue (GRTBFR=8.4%; GTRT=8.3%). There was also a significant change in body fat (p=0.023-0.043), with significant effect sizes for strength and skeletal muscle tissue (0.41-2.27), respectively. These results suggest that both resistance training interventions promoted muscle hypertrophy, body fat reduction and positive impact on muscle strength in people living with HIV/AIDS. Resistance training with blood flow restriction proved to be an effective alternative to include patients with marked physical weakness, unable to engage in regular strength training programme.ClinicalTrials.gov identifier: NCT02783417.

Lipodystrophy diagnosis in people living with HIV/AIDS: prediction and validation of sex-specific anthropometric models.

BACKGROUND: Body composition alterations, or lipodystrophy, can lead to serious health problems in people living with HIV/AIDS (PLWHA). The objectives of this study are to predict and validate sex-specific anthropometric predictive models for the diagnosis of lipodystrophy in PLWHA. METHODS: A cross-sectional design was employed to recruit 106 PLWHA (men = 65 and women = 41) in Brazil during 2013-2014. They were evaluated using dual-energy X-ray absorptiometry, and 19 regions of body perimeters and 6 skinfold thicknesses were taken. Sex-specific predictive models for lipodystrophy diagnosis were developed through stepwise linear regression analysis. Cross-validations using predicted residual error sum of squares was performed to validate each predictive model. RESULTS: Results support the use of anthropometry for the diagnosis of lipodystrophy in men and women living with HIV/AIDS. A high power of determination with a small degree of error was observed for lipodystrophy diagnosis for men in model six (r2 = 0.77, SEE = 0.14, r2PRESS = 0.73, SEE PRESS = 0.15), that included ratio of skinfold thickness of subscapular to medial calf, skinfold thickness of thigh, body circumference of waist, formal education years, time of diagnosis to HIV months, and type of combined antiretroviral therapy (cART) (with protease inhibitor "WI/PI = 1" or without protease inhibitor "WO/PI = 0"); and model five for women (r2 = 0.78, SEE = 0.11, r2PRESS = 0.71, SEE PRESS = 0.12), that included skinfold thickness of thigh, skinfold thickness of subscapular, time of exposure to cART months, body circumference of chest, and race (Asian) ("Yes" for Asian race = 1; "No" = 0). CONCLUSIONS: The proposed anthropometric models advance the field of public health by facilitating early diagnosis and better management of lipodystrophy, a serious adverse health effect experienced by PLWHA.