Multivariate analysis of lifestyle, constitutive and body composition factors influencing bone health in community-dwelling older adults from Madeira, Portugal

This study describes the association between habitual physical activity (PA), other lifestyle/constitutive factors, body composition, and bone health/strength in a large sample of older adults from Madeira, Portugal. This cross-sectional study included 401 males and 401 females aged 60-79 years old. Femoral strength index (FSI) and bone mineral density (BMD) of the whole body, lumbar spine (LS), femoral neck (FN), and total lean tissue mass (TLTM) and total fat mass (TFM) were determined by dual-energy X-ray absorptiometry-DXA. PA was assessed during face-to-face interviews using the Baecke questionnaire and for a sub-sample by Tritrac accelerometer. Demographic and health history information were obtained by telephone interview through questionnaire. The relationship between habitual PA variables and bone health/strength indicators (whole body BMD, FNBMD, LSBMD, and FSI) investigated using Pearson product-moment correlation coefficient was similar for females (0.098≤r≤0.189) and males (0.104≤r≤0.105). Results from standard multiple regression analysis indicated that the primary and most significant predictors for FNBMD in both sexes were age, TLTM, and TFM. For LSBMD, the most significant predictor was TFM in men and TFM, age, and TLTM in females. Our regression model explained 8.3-14.2% and 14.8-29.6% of the total variance in LSBMD and FNBMD for males and females, respectively. This study suggests that habitual PA is minimally but positively associated with BMD and FSI among older adult males and females and that body composition factors like TLTM and TFM are the strongest determinants of BMD and FSI in this population

Physical fitness in morbidly obese patients: effect of gastric bypass surgery and exercise training

Background There is a growing consensus that bariatric surgery is currently the most efficacious and long-term treatment for clinically severe obesity. However, it remains to be determined whether poor physical fitness, an important characteristic of these patients, improves as well. The purpose of this pilot study is to investigate the effect of gastric bypass surgery on physical fitness and to determine if an exercise program in the first 4 months is beneficial. Methods Fifteen morbidly obese patients (BMI 43.0 kg/m(2)) were tested before and 4 months after gastric bypass surgery. Eight of them followed a combined endurance and strength training program. Before and after 4 months the operation, anthropometrical characteristics were measured, and an extensive assessment of physical fitness (strength, aerobic, and functional capacity) was performed. Results Large-scale weight loss through gastric bypass surgery results in a decrease in dynamic and static muscle strength and no improvement of aerobic capacity. In contrast, an intensive exercise program could prevent the decrease and even induced an increase in strength of most muscle groups. Together with an improvement in aerobic capacity, functional capacity increased significantly. Both groups evolved equally with regard to body composition (decrease in fat mass and fat-free mass). Conclusions An exercise training program in the first 4 months after bariatric surgery is effective and should be promoted, considering the fact that physical fitness does not improve by weight loss only

The influence of muscular action on bone strength via exercise

Mechanical stimuli influence bone strength, with internal muscular forces thought to be the greatest stressors of bone. Consequently, the effects of exercise in improving and maintaining bone strength have been explored in a number of interventional studies. These studies demonstrate a positive effect of high-impact activities (i.e. where large muscle forces are produced) on bone strength, with benefits being most pronounced in interventions in early pubertal children. However, current studies have not investigated the forces acting on bones and subsequent deformation, preventing the development of optimised and targeted exercise interventions. Similarly, the effects of number and frequency of exercise repetitions and training sessions on bone accrual are unexplored. There are conflicting results as to gender effects on bone response to exercise, and the effects of age and starting age on the osteogenic effects of exercise are not well known. It also appears that exercise interventions are most effective in physically inactive people or counteracting conditions of disuse such as bed rest. Bone strength is only one component of fracture risk, and it may be that exercise resulting in improvements in, e.g., muscle force/power and/or balance is more effective than those whose effects are solely osteogenic. In summary, exercise is likely to be an effective tool in maintaining bone strength but current interventions are far from optimal. © Springer Science+Business Media 2013

O efeito do destreinamento de força muscular em meninos pré-púberes El efecto del desentrenamiento muscular en niños pre-puberes Effect of the muscular strength detraining in prepubertal boys

A treinabilidade da força em crianças tem sido bem explorada, mas ainda existe um questionamento a respeito de como a força diminui quando elas param de treinar. O objetivo deste estudo foi avaliar o efeito de 12 semanas de destreino na força muscular de meninos treinados por 12 semanas. Sete meninos pré-púberes (EX, 9,4 &plusmn; 1,6 anos) treinaram três séries de 15 repetições, três vezes por semana, por 12 semanas. O treinamento foi supervisionado e desenvolvido em equipamentos; consistiu de oito exercícios, incluindo extensão de joelhos (EJ) e flexão de cotovelos (FC). O teste de 1-RM de EJ e FC foi feito antes e após o treinamento e após 12 semanas de destreinamento. Um grupo similar de meninos (n = 7, 9,7 &plusmn; 1,7 anos), que não treinou, serviu como grupo controle (CO). Após o treinamento o grupo EX aumentou (p < 0,05) 1-RM de 14,6 &plusmn; 9,8 para 26,2 &plusmn; 12,9kg na EJ, e 4,7 &plusmn; 2 para 7,9 &plusmn; 4,1kg na FC. Após 12 semanas de destreinamento, 1-RM foi 19,6 &plusmn; 11,2 na EJ e 6,5 &plusmn; 3kg na FC. O decréscimo na força não foi estatisticamente significativo (p > 0,05). Quando corrigida pelo peso corporal e pela massa corporal magra (MCM), 1-RM de EJ diminuiu significativamente (p < 0,05), de 0,64 &plusmn; 0,1 para 0,45 &plusmn; 0,1 e de 0,83 &plusmn; 0,2 para 0,61 &plusmn; 0,2 do peso corporal e MCM respectivamente. A força de FC não diminuiu significativamente quando corrigida pelo peso corporal e pela MCM. O grupo CO não mudou os níveis de força nas primeiras 12 semanas, mas após 24 semanas, apresentou um aumento de 41% no 1-RM de EJ e 53% na FC. Conclui-se que após o destreinamento a força muscular em valores absolutos não apresenta redução significativa; os resultados são significativos apenas quando corrigido pelo peso e MCM, e isso se evidencia apenas nos membros inferiores.<br>El entrenamiento de la fuerza en niños ha sido bien explorada, mas existe en la actualidad un cuestionamiento al respecto de como la fuerza disminuye cuando los mismos paran de entrenar. El objetivo de este estudio fue evaluar el efecto del desentrenamiento de 12 semanas sobre la fuerza muscular en niños entrenados por 12 semanas. Siete niños pre-púberes (EX, 9,4 &plusmn; 1,6 años) entrenaron tres series de 15 repeticiones, tres veces por semana, por 12 semanas. El entrenamiento fué supervisado y desarrollado en equipamientos, consistió de ocho ejercicios, incluyendo extensión de los codos (EJ) y la flexión de las rodillas (FC). El test de 1-RM de EJ y FC fué hecho antes y después del entrenamiento y después de 12 semanas de desentrenamiento. Un grupo similar de niños (n = 7, 9,7 &plusmn; 1,7 años), que no entrenó sirvió como grupo control (CO). Después del entrenamiento el grupo EX aumentó (p < 0.05) 1-RM de 14,6 &plusmn; 9,8 para 26,2 &plusmn; 12,9 Kg. en la EJ, y 4,7 &plusmn; 2 para 7,9 &plusmn; 4,1 Kg. en la FC. Después de 12 semanas de desentrenamiento, 1-RM fué de 19,6 &plusmn; 11,2 en la EJ y 6,5 &plusmn; 3 Kg. en la FC. La disminución de la fuerza no fue estadísticamente significativo (p > 0,05). Cuando fue corregido por el peso corporal y por la masa corporal magra (MCM), 1-RM de EJ disminuyó significativamente (p < 0,05) de 0,64 &plusmn; 0,1 para 0,45 &plusmn; 0,1 y de 0,83 &plusmn; 0,2 para 0,61 &plusmn; 0,2 del peso corporal y MCM respectivamente. La fuerza de FC no disminuyó significativamente cuando corregida por el peso corporal y por la MCM. El grupo CO no cambió los niveles de fuerza en las primeras 12 semanas, mas después de las 24 semanas, presentó un aumento del 41% en el 1-RM de EJ y del 53% en la FC. Se concluye que después del desentrenamiento la fuerza muscular en valores absolutos no presenta ninguna reducción significativa; los resultados pasan a ser significativos cuando son corregidos por el peso y la MCM, y eso se evidencia apenas en los miembros inferiores.<br>The strength trainability in children has been widely explored, however, there is still a questioning with regard to how strength decreases when they stop training. The objective of this study was to evaluate the effect of 12 weeks of muscular strength detraining of boys trained for 12 weeks. Seven prepubertal boys (EX 9.4 &plusmn; 1.6 years of age) trained three series of 15 repetitions, three times a week for 12 weeks. The training, supervised and developed in equipments, consisted of eight exercises including knee extension (KE) and elbow flexion (EF). The 1-RM test of NE and EF was performed before and after training and 12 weeks after detraining. A similar group of boys (n = 7, 9.7 &plusmn; 1.7 years), who did not train served as control (CO). After training, the group EX increased (p < 0.05) 1-RM from 14.6 &plusmn; 9.8 to 26.2 &plusmn; 12.9 kg in KE, and 4.7 &plusmn; 2 to 7.9 &plusmn; 4.1 kg in FC. After 12 weeks of detraining, the 1-RM was 19.6 &plusmn; 11.2 in NE and 6.5 &plusmn; 3 kg in FC. The decrease on strength was not statistically significant (p > 0,05). When corrected by the body weight and by the lean body mass (LBM), the 1-RM of NE decreased significantly (p > 0,05) from 0.64 &plusmn; 0.1 to 0.45 &plusmn; 0.1 and from 0.83 &plusmn; 0.2 to 0.61 &plusmn; 0.2 of the body weight and LBM, respectively. The EF strength did not decrease significantly when corrected by the body weight and LBM. The strength levels did not change in the first 12 weeks for group CO, however, after 24 weeks, it presented an increase of 41% in the 1-RM of KE and 53% in EF. One concludes that, after detraining, the muscular strength presented no significant reduction in absolute values; the results are significant only when corrected by weight and LBM and it is only evidenced for the lower limbs

Influence of puberty on muscle development at the forearm.

Despite its fundamental importance for physical development, the growth of the muscle system has received relatively little consideration. In this study, we analyzed the relationship between cross-sectional area (CSA) of forearm muscles and maximal isometric grip force with age and pubertal stage. The study population comprised 366 children, adolescents, and young adults from 6 to 23 yr of age (185 female) and 107 adults (88 female) aged 29 to 40 yr. By use of peripheral quantitative computed tomography, muscle CSA was determined at the site of the forearm, whose distance to the ulnar styloid process corresponded to 65% of forearm length. Both muscle CSA and grip force were higher in prepubertal boys than in girls. The gender differences decreased until pubertal stage 3 and reincreased thereafter. In girls at pubertal stage 5, muscle CSA no longer increased with age (P > 0.4), whereas there was still some age-related increase in grip force (P = 0.02). In boys at pubertal stage 5, both muscle CSA and grip force continued to increase significantly with age (P < 0.005 each). Specific grip force (grip force per muscle CSA) adjusted for forearm length increased by almost one-half between 6 and 20 yr of age, with no difference between the genders. In conclusion, forearm muscle growth takes a gender-specific course during puberty, indicating that it is influenced by hormonal changes. However, the increase in specific grip force is similar in both genders and thus appears to be independent of sex hormones

Avaliação da saúde e aptidão física para recomendação de exercício em pediatria

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