Gender-based differences in substrate use during exercise at a self-selected pace.

The aim of this study was to investigate gender-based differences in substrate use during exercise at a self-selected pace. Seventeen men and 17 women performed a maximal exercise test and a 20-minute bout of self-paced treadmill walking to determine carbohydrate and fat oxidation rates. Gas exchange measurements were performed throughout the tests, and stoichiometric equations were used to calculate substrate oxidation rates. For each individual, a best-fit polynomial curve was constructed using fat oxidation rate (g·min(-1)) vs. exercise intensity (percentage of maximal oxygen uptake, % VO(2)max). Each individual curve was used to obtain the following variables: maximal fat oxidation (MFO), the peak rate of fat oxidation measured over the entire range of exercise intensities; fat(max), the exercise intensity at which the MFO was observed; and fat(max) zone, range of exercise intensities with fat oxidation rates within 10% of fat oxidation rates at fat(max). Although the MFO was similar between genders, fat(max) was lower in men than in women. Similarly, the "low" and "high" borders of the fat(max) zone were lower in men than in women. During exercise at a self-selected pace, carbohydrate oxidation rates were greater in men than in women, despite no gender-based differences in fat oxidation rates. However, fat oxidation contribution to total energy expenditure (EE) was greater in women than in men, despite no gender-based differences in the exercise intensity. In conclusion, although both genders self-selected a similar exercise intensity, the contribution of fat oxidation to EE is greater in women than in men. Interestingly, both genders self-selected an exercise intensity that falls within the fat(max) zone.

Psychophysiological responses to self-paced treadmill and overground exercise.

UNLABELLED: Speculation exists that a positive affective response experienced during exercise may play an important role in predicting exercise adherence. Previous studies using self-paced exercise protocols have been associated with health benefits and pleasant experiences. However, all of these studies were conducted in laboratories, and consequently, the external validity of the findings may be questionable. PURPOSE: To determine whether environmental settings (treadmill vs overground) differentially influence physiological, perceptual, and affective responses to exercise at a self-selected pace. METHODS: Thirty-four individuals (17 men and 17 women) between 18 and 30 yr volunteered to participate in this study. During the orientation session, individuals underwent an initial screening, anthropometric measurements, and familiarization with the experimental procedures. Next, subjects underwent a maximal treadmill test. In the two experimental trials, participants performed 20-min bouts of treadmill and overground walking at a self-selected pace, which were completed in a counterbalanced order. At least 48 h separated experimental trials. RESULTS: Using repeated-measures ANOVA, overground walking speed was significantly faster than treadmill walking speed (P < 0.01) during the 20-min bout of self-paced exercise. However, exercise intensity (%VO2R and %HRR) and perceived exertion during the session of overground walking were significantly lower (P < 0.05) when compared with those during the treadmill session. In addition, affective valence was more positive during the session of overground walking than during the treadmill session (P < 0.01). CONCLUSIONS: These data extend previous findings by showing that environmental setting influences physiological, perceptual, and affective responses during exercise at a self-selected pace. Self-paced exercise performed over ground resulted in lower perceptual and more positive affective responses.

Comparação das respostas fisiológicas e perceptuais obtidas durante caminhada na esteira em ritmo autosselecionado entre os sexos / Physiological and perception responses comparison during treadmill walking at self-selected pace between genders

O objetivo do presente estudo foi comparar as respostas fisiológicas e perceptuais entre os sexos durante a caminhada na esteira em ritmo autosselecionado. Participaram 17 homens e 17 mulheres, fisicamente ativos, com média de idade de 23,32 ± 3,06 anos, submetidos a duas sessões experimentais: (I) avaliação antropométrica e teste incremental máximo, e (II) um teste de 20 minutos de caminhada na esteira em ritmo autosselecionado. Para a análise estatística, empregou-se teste t de Student para medidas independentes no intuito de verificar as possíveis diferenças entre os sexos, adotando p < 0,05. A velocidade de caminhada autosselecionada pela amostra masculina foi superior à verificada na feminina (1,65 ± 0,18 e 1,50 ± 0,12m·seg-1, respectivamente) o que consequentemente resultou em maior O2 absoluto nos homens comparado às mulheres (21,2 ± 5,5 e 18,3 ± 2,7, respectivamente). No entanto, ambos os sexos buscaram caminhar em mesma intensidade relativa % O2máx, (37,5 ± 10,7 homens e 40,3 ± 7,2 mulheres). Em relação à percepção subjetiva de esforço (PSE), podemos verificar que ambos os sexos não demonstraram diferenças significativas (10,2 ± 1,0 homens e 9,8 ± 1,2 mulheres). Os achados do presente estudo demonstram que, independente do sexo, jovens adultos fisicamente ativos autosselecionaram similar intensidade relativa que refletiu em similar PSE. Além disso, a caminhada em intensidade autosselecionada demonstra-se como estímulo insuficiente para proporcionar melhora no condicionamento cardiorrespiratório nesta população.

The aim of this study was to compare physiological and perception responses between genders during treadmill walking at self-selected pace. 17 men and 17 women aged 23.32 ± 3.06 yr were investigated: (I) anthropometric assessment and incremental exhaustion test, (II) a 20-minute walking bout on treadmill at their self-selected pace. The independent t test was utilized to verify any gender differences, with a level of p < 0.05. The self-selected walking pace was significantly greater in men than women (1.65 ± 0.18 and 1.50 ± 0.12 m·sec-1, respectively), and consequently resulted in higher absolute VO2 for men compared to women (21.2 ± 5.5 and 18.3 ± 2.7, respectively). However, both genders self-selected a similar relative exercise intensity %VO2max (37.5 ± 10.7 and 40.3 ± 7.2 for men and women, respectively). The subjective perceived exertion (SPE) did not differ between genders (10.2 ± 1.0 and 9.8 ± 1.2 for men and women, respectively). The results of the present study demonstrated that regardless of gender, physically active young adults self-selected a similar relative exercise intensity that reflected in similar SPE. Furthermore, gait at self-selected intensity was insufficient to improve cardiorespiratory fitness in this sample.

Urinary incontinence and waist circumference in older women.

OBJECTIVE: the study aims to determine the association between adiposity and fitness with urinary incontinence (UI) in older women. METHODS: a cross-sectional study was conducted in southern Brazil. A sample of 1,069 urban women, age 60+, was assessed for UI (in-person interview), adiposity (body mass index [BMI] and waist circumference [WC]) and fitness. Logistic regression models were developed to assess the association between UI and the independent variables-adiposity (BMI and WC) and fitness indicators. All models were adjusted for age, socioecomomic level, diabetes and hypertension. RESULTS: BMI and functional tests were not significantly associated with UI. WC was an independent and significant predictor. Relative to women in the lowest quartile of WC, odds ratios for UI were 1.98 for WC of 79-86 cm, 2.07 for WC of 86-94 cm and 2.24 for WC >94 cm (P = 0.03). CONCLUSION: central adiposity, as indicated by large WC, increases the risk of UI. Intra-abdominal pressure and its effect on urethral structures may be responsible for this increased risk. Older women should be counselled on the risk of central obesity for UI.