Body fat, but not muscle quality, is related to perceived fatigue in young-adult active and inactive women / Gordura corporal, mas não a qualidade muscular, é relacionada a fadiga percebida em mulheres adultas jovens ativas e inativas

Abstract The purpose of this study was to investigate the association of perceived fatigue with body composition and muscle quality (strength, thickness and specific torque) in young adult women. Fifty-one healthy women (31.98 ± 6.88 years) were assessed regarding perceived fatigue, body composition, knee extensors muscle strength, muscle thickness, and muscle quality. The short version of International Physical Activity Questionnaire was applied to classify subjects as active or inactive. To examine the relationship between perceived fatigue and dependent variables, the Pearson's correlation was performed. Perceived fatigue was significantly correlated (p < 0.05) with body weight (r = 0.469), body mass index (r = 0.369), fat mass (r = 0.469), percent body fat (r = 0.396), and relative peak torque (r = -0.378). Additionally, inactive women had significantly greater (p < 0.05) body weight, body mass index, fat mass, percent body fat, and perceived fatigue than active women. Perceived fatigue is related to body weight and fat mass, but not to muscle strength or muscle quality. Moreover, physically active women showed lower perceived fatigue, body weight, and body fat compared to physically inactive women. These results suggest that body fat may play a role in perceived fatigue and physical activity could attenuate such symptom.

Resumo O objetivo deste estudo foi investigar a associação da fadiga percebida com a composição corporal e a qualidade muscular (força, espessura e torque específico) em mulheres adultas jovens. Cinquenta e uma mulheres foram avaliadas quanto a fadiga percebida, a composição corporal, a força muscular de extensão de joelho, a espessura muscular e a qualidade muscular. A versão curta do Questionário Internacional de Atividade Física foi aplicada para classificar as voluntárias como ativas ou inativas.Para examinar a relação entre a fadiga percebida e as variáveis dependentes, a correlação de Pearson foi executada. A fadiga percebida apresentou relação significativa (p < 0,05) com o peso corporal (r = 0,469), IMC (r = 0,369), massa gorda (r = 0,469), percentual de gordura (r = 0,396) e pico de torque relativo (r = -0,378). Adicionalmente, mulheres inativas apresentaram maior (p < 0,05) peso corporal, índice de massa corporal, massa gorda, percentual de gordura e fadiga percebida, comparadas com mulheres ativas. A fadiga percebida se relaciona com o peso corporal e com a gordura corporal, mas não com a força muscular ou com a qualidade muscular. Além disso, mulheres fisicamente ativas tem uma menor fadiga percebida, peso corporal e gordura corporal do que mulheres fisicamente inativas. Esses resultados sugerem que a gordura corporal exerce um papel importante na fadiga percebida e que a atividade física pode atenuar esse sintoma.

Greater volumes are required to reduce muscle performance in well-trained individuals / Grandes volumes são necessários para reduzir o desempenho muscular em indivíduos bem treinados

Abstract A specific drop jumps (DJs) protocol (using 100 jumps) has been largely used to induce muscle damage. However, it failed to show relevant drop in performance in well-trained individuals. Trained subjects may require a protocol with greater volume to induce decrease of muscle performance. The aim of this study was to assess muscle performance after two DJs damaging protocols with different volumes in well-trained individuals. Eighteen strength and/or power-trained males (4.92 ± 2.78 years of training experience) were randomly assigned into one of two groups: DJ100 (five sets of 20 DJs) or DJ140 (seven sets of 20 DJs), with 2-min of rest interval. DJs were performed from a 60-cm box. After landing, the volunteers performed a maximal vertical rebound jump. Muscle swelling increased significantly on both DJ100 and DJ140 (p < 0.001). Maximal isometric torque (MIT) decreased significantly on both DJ100 (p = 0.005) and DJ140 (p < 0.001). MIT showed no between-group difference on pre-assessment (p = 0.815). However, on post-assessment, MIT was significantly lower on DJ140 than DJ100 (p = 0.043). Countermovement jump (CMJ) decreased significantly on DJ140 (p = 0.001), but not on DJ100 (p = 0.802). There was no between-group difference on pre-assessment (p = 0.978). However, on post-assessment, CMJ was significantly lower on DJ140 than DJ100 (p = 0.038). DJ140 induced greater drop in isometric strength than DJ100 and only DJ140 significantly reduced jump performance. These results demonstrated that well-trained individuals require a great volume of DJs to reduce substantially muscle performance.

Resumo Um protocolo específico de Drop Jumps (DJs), com 100 saltos, tem sido amplamente utilizado para induzir o dano muscular. Entretanto, este protocolo tem falhado em mostrar uma queda relevante em indivíduos treinados. Objetivou-se avaliar o desempenho muscular após dois protocolos de DJs com diferentes volumes em indivíduos treinados. Dezoito homens treinados em força e/ou potência (4,92 ± 2,78 anos de treinamento) foram aleatoriamente designados em um dos dois grupos: DJ100 (cinco séries de 20 DJs) ou DJ140 (sete séries de 20 DJs), com 2 minutos entre as séries. Os DJs foram executados de uma caixa de 60 cm de altura. Após a aterrisagem, os voluntários executaram um salto vertical máximo. O inchaço muscular aumentou significativamente em ambos os grupos (p < 0,001). O torque isométrico máximo (TIM) reduziu significativamente tanto no DJ100 (p = 0,005) quanto no DJ140 (p < 0,001). O TIM não apresentou diferenças entre grupos no momento pré (p = 0,815). Entretanto, no momento pós, o TIM foi significativamente inferior no DJ140 em relação ao DJ100 (p = 0,043). O salto com contra movimento (SCM) reduziu significativamente no DJ140 (p = 0,001), mas não no DJ100 (p = 0,802). No momento pós, o SCM foi significativamente inferior no DJ140 em relação ao DJ100. O DJ140 induziu uma queda maior na força isométrica em relação do DJ100, e somente o DJ140 reduziu significativamente o desempenho no salto. Esses resultados demonstraram que indivíduos bem treinados requerem um grande volume DJs para reduzir substancialmente o desempenho muscular.

Pre-exercise ß-hydroxy-ß-methylbutyrate free-acid supplementation improves work capacity recovery: a randomized, double-blinded, placebo-controlled study.

The purpose of this study was to investigate the effects of a single-dose of ß-hydroxy-ß-methylbutyrate free acid (HMB-FA) supplementation on muscle recovery after a high-intensity exercise bout. Twenty-three trained young males were randomly assigned to receive either a single-dose supplementation of 3 g of HMB-FA (n = 12; age, 22.8 ± 3.0 years) or placebo (PLA; n = 11; age, 22.9 ± 3.1 years). A muscle damage protocol was applied 60 min after supplementation, and consisted of 7 sets of 20 drop jumps from a 60-cm box with 2-min rest intervals between sets. Muscle swelling, countermovement jump (CMJ), maximal voluntary isometric torque (MVIT), and work capacity (WC) were measured before, immediately after, and 24, 48, and 72 h after the exercise protocol. Muscle swelling, CMJ, and MVIT changed similarly in both groups after the exercise protocol (p < 0.001), but returned to pre-exercise levels after 24 h in both groups. WC decreased similarly in both groups after the exercise protocol (p < 0.01). For HMB-FA, WC returned to pre-exercise level 24 h after exercise protocol. However, for PLA, WC did not return to pre-exercise level even 72 h after the exercise protocol. In summary, a single-dose of HMB-FA supplementation improved WC recovery after a high-intensity exercise bout. However, HMB-FA did not affect the time-course of muscle swelling, MVIT, and CMJ recovery.

Association between obesity, risk of falls and fear of falling in older women / Associação entre obesidade, risco de quedas e medo de cair em mulheres idosas

Abstract The aim of this cross-sectional study was to investigate the association between obesity, risk of falls and fear of falling in older women. Two hundred and twenty-six volunteers (68.05 ± 6.22 years, 68.06 ± 11.79 kg, 1.56 ± 0.06 m) were classified as normal weight, overweight or obese, according to the body mass index. Risk of falls and fear of falling were evaluated using QuickScreen Clinical Falls Risk Assessment and Falls Efficiency Scale - International (FES-I), respectively. Comparisons between groups were conducted using Chi-square and ANOVA One-way tests. The significance level was set at p< 0.05. Obesity was associated with greater probability of falls (p< 0.001), which may be partly explained by decreased muscle strength (p< 0.001) and reaction time (p< 0.001). In addition, significant differences between groups was observed in FES-I score (p< 0.01), with obese women showing more pronounced fear of falling (30.10 ± 8.4) than normal weigh (25. 33 ± 7.11, p< 0.01) and overweight subjects (26.97 ± 7.05, p< 0.05). These findings corroborate previous evidence pointing obesity as a major risk factor for falls. Therefore, health professionals dealing with fall prevention should consider the effects of overweight.

Resumo O objetivo deste estudo transversal foi verificar a associação entre obesidade, risco de quedas e medo de cair em mulheres idosas. Duzentas e vinte e seis voluntárias (68,05 ± 6,22 anos; 68,06 ± 11,79 kg; 1,56 ± 0,06 m) foram classificadas em eutróficas, sobrepesadas ou obesas, de acordo com o índice de massa corporal. O risco de quedas e o medo de cair foram mensurados por meio do QuickScreen Clinical Falls Risk Assessment e da Escala de Eficácia de Quedas - Internacional (FES-I), respectivamente. Para comparação entre grupos, empregaram-se os testes Qui-quadrado e ANOVA One-way. O nível de significância adotado foi de p< 0,05. A obesidade foi associada a uma probabilidade de quedas aumentada (p< 0,001), o que pode ser parcialmente explicado pela diminuição da força muscular (p< 0,001) e do tempo de reação (p< 0,001). Adicionalmente, observou-se diferença significativa entre os grupos no escore da FES-I (p< 0,01), sendo que as idosas obesas exibiram um medo de cair mais acentuado (30,10 ± 8,4) que as eutróficas (25,33 ± 7,11; p< 0,01) e as sobrepesadas (26,97 ± 7,05; p< 0,05). Esses achados se agregam a evidências prévias que apontam a obesidade como um importante fator de risco para quedas em idosos. Portanto, profissionais da saúde devem considerar os efeitos do excesso de peso ao lidar com prevenção de quedas.

Obesity is Associated With Altered Plantar Pressure Distribution in Older Women.

Increased plantar pressure has been found to be related with greater risk of falling. Although there is evidence suggesting that obesity is linked to foot disorders, the association between obesity and plantar pressure of older adults has been poorly investigated. The purpose of this study was to examine the association between obesity and plantar pressure distribution and to explore its relationship with body fat distribution. Two hundred and eleven older women took part in this cross-sectional study. Body mass index was taken for obesity classification. Whole body, android, and gynoid fat percentage was assessed using dual-energy x-ray absorptiometry. Peak plantar pressure was evaluated during gait using an Emed AT-4 pressure platform. Obese volunteers generated greater peak pressure at midfoot (187.26 kPa) compared to both normal weight (128.52 kPa, p < .001) and overweight (165.74 kPa, p < .001). Peak plantar pressure at midfoot was also greater in overweight compared to normal weight (p < .001). At forefoot, peak pressure was higher in the obese (498.15 kPa) compared to normal weight volunteers (420.41 kPa, p = .007). Additionally, whole body, android, and gynoid fat percentage were significantly associated with peak pressure at midfoot and forefoot. Therefore, clinicians dealing with falls should consider the effect of increased body weight on plantar pressure.

Acute metabolic response to fasted and postprandial exercise.

The aim of this study was to analyze the acute metabolic response to exercise in fasting and postprandial. For this, ten individuals were submitted to an incremental treadmill test, with an initial speed of 5 and 1 km/h increments every minute, with no inclination, and a body composition assessment. After this 1st day, all volunteers were submitted to two experimental procedures (fasting and postprandial), with an aerobic exercise performed for 36 minutes at 65% of maximal oxygen consumption. At postprandial procedure, all subjects ingested a breakfast containing 59.3 g of carbohydrate (76.73%), 9.97 g of protein (12.90%), 8.01 g of lipids (10.37%), with a total energy intake of 349.17 kcal. An analysis of plasma concentration of triglycerides, lactate, and glucose was performed in two stages: before and after exercise. The Shapiro-Wilk test was used to verify the normality of the data. For analysis of glucose concentration, plasma lactate, and triglycerides, we used a repeated measures analysis of variance factorial 2×2, with Bonferroni multiple comparison test. The significance level of P<0.05 was adopted. The results indicated a maintenance level of glucose at fasting and a decrease in glucose concentration at postprandial exercise. Both conditions increase plasma lactate. Triglycerides also increased in the two experimental conditions; however, after exercise fasting, the increase was significantly higher than in the postprandial exercise. These data suggest that both exercises could increase plasma lactate and triglycerides. However, exercise performed in fasting condition decreases glucose concentration and increases triglycerides, even more than postprandial exercise.