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Background To propose cut-off points for older adults’ weakness for upper and lower limbs muscle strength normalized by body size with the ratio standard/muscle quality and allometric scaling. Methods Ninety-four community-dwelling older adults (69.1% women) were assessed for 49 body-size variables (anthropometry, body composition and body indexes), handgrip strength (HGS), one maximum repetition measurement for knee extensors (1RM), isokinetic knee extension peak torque at 60°/s (PT), and six-minute walk test (6MWT). Ratio standard or muscle quality (muscle strength/body size) and allometric scaling (muscle strength/body sizeb; when b is the allometric exponent) were applied for body-size variables significantly correlated with HGS, 1RM and PT. Cut-off points were computed according to sex based on mobility limitation (6MWT < 400 m) with ROC curve and Youden index. Results Absolute HGS, 1RM and PT cut-off points were not adequate because they were associated with body size (r > 0.30). But it was corrected with muscle strength normalization according to body size-variables: HGS (n = 1); 1RM (n = 24) and PT (n = 24). The best cut-off points, with the highest area under the curve (AUC), were found after normalization for men: HGS/forearm circumference (1.33 kg/cm, AUC = 0.74), 1RM/triceps skinfold (4.22 kg/mm, AUC = 0.81), and PT/body mass*height0.43 (13.0 Nm/kg*m0.43, AUC = 0.94); and for women: HGS/forearm circumference (1.04 kg/cm, AUC = 0.70), 1RM/body mass (0.54 kg/kg, AUC = 0.76); and PT/body mass0.72 (3.14 Nm/kg0.72; AUC = 0.82). Conclusions Upper and lower limbs muscle weakness cut-off points standardized according to body size were proposed for older adults of both sexes. Normalization removes the effect of extreme body size on muscle strength (both sexes) and improves the accuracy to identify weakness at population level (for women, but not in men), reducing the risk of false-negative/positive cases.

Background: Dynamic knee extensor muscle strength is a valid measure among healthy older adults but has not been tested in the sarcopenia condition. This study's objective was to test the validity of a one-repetition submaximal strength protocol to measure dynamic knee extension strength in older adults with and without sarcopenia. Methods: Ninety-four physically independent older adults (female: n = 64, 60 to 85 years; male: n = 29, 60 to 85 years) participated in this study in Brazil during 2016-2017. Sarcopenia was classified and isokinetic unilateral knee extension strength was measured at 60°/s. Bilateral dynamic knee extension strength was estimated with an extensor chair using one-repetition submaximal protocol. Validity was determined using Spearman's correlation with isokinetic muscle strength. Results: The frequency of sarcopenia was 11.7%. Sarcopenic individuals presented lower body mass, body mass index and skeletal muscle index. Only chronological age was higher among the sarcopenic individuals. A high correlation was found between isokinetic unilateral knee extension strength and bilateral estimated one-repetition with submaximal protocol (r = 0.74; p < 0.001), when the presence (r = 0.71; p = 0.014) and absence of sarcopenia (r = 0.74; p < 0.001) were considered. The validity of the one-repetition submaximal protocol for bilateral knee extension was confirmed. Conclusions: The estimated measure of bilateral knee extension muscle strength can be used to monitor adaptations promoted by physical exercise for older adults with and without sarcopenia. The validation enable studies that will propose cutoff points to identify sarcopenia with this submaximal protocol. This will enable early diagnosis and better management of sarcopenia, a disease with adverse impacts for older adults.

O sobrepeso e o desenvolvimento motor pobre nas crianças e adolescentes, que podem ser constatados em diferentes regiões e classes sociais, decorrem sobretudo do estilo de vida sedentário. Por si, o sedentarismo é um fator de risco para as doenças crônicas e mortalidade, principalmente na vida adulta, e por isso deve ser combatido desde a infância. Urbanização, desenvolvimento industrial, meios de comunicação, aparelhos eletrônicos, falta de estímulo e de exemplo dos pais se constituem num ambiente favorável para prática insuficiente de atividades físicas por até 81% das crianças e adolescentes. Por outro lado, há grande número de possibilidades para prática de exercícios de intensidade moderada a vigorosa, que efetivamente possam proporcionar benefícios para os jovens. Quando a Educação Física escolar não é suficiente, seja por seu conteúdo ou limitação de número de aulas, as escolas de esportes, os exercícios de musculação nas academias, o treinamento funcional e o CrossFit estão entre as opções que podem motivar os jovens. Os esportes e modalidades de treinamento proporcionam o desenvolvimento de uma gama de capacidades físicas, o pleno desenvolvimento somático e de aspectos cognitivos e emocionais. Cabem aos pais dois importantes papéis neste início de caminhada dos filhos para o estilo de vida ativo. Em primeiro estimular e deixar de lado crenças e informações enganosas sobre riscos de algumas modalidades de treinamento; em segundo garantir que os filhos pratiquem a modalidade escolhida sob supervisão de um profissional de Educação Física, de forma a garantir a correção postural durante os exercícios, execução correta dos movimentos, o feedback para os aprendizes, a adequada densidade das sessões e o cumprimento dos princípios do treinamento físico para proporcionar os melhores benefícios.

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