ABSTRACT
Walking is the most accessible and common type of physical activity. Exercising at one's self-selected intensity could provide long-term benefits as compared to following prescribed intensities. The aim of this study was to simultaneously examine metabolic, perceptual, spatiotemporal and stability parameters at an absolute 3 km·h-1 speed range around the individual preferred walking speed (PWS). Thirty-four young sedentary adults (18 women) volunteered to walk at seven speeds relative to their PWS in 3-min trials interspaced with 3-min rest intervals. Results indicated a significant main effect of speed on all studied variables. While metabolic, perceptual and spatiotemporal values were sensitive to the smallest change in speed (i.e., 0.5 km·h-1), a significant increase in the rate of carbohydrate oxidation and decrease in %fat oxidation were only observed at speeds above PWS. Results also revealed significantly higher coefficients of variation for stride characteristics at speeds below PWS only. Moreover, analyses of best fit models showed a quadratic relationship between most variables and speed, with the exceptions of metabolic cost of transport, rating of perceived exertion and stride duration that changed exponentially with speed. PWS coincided with optimized mechanical efficiency, fuel oxidation and gait stability. This indicated that walking below PWS decreased both mechanical efficiency and stability of gait, while walking above PWS increased carbohydrate oxidation. Those factors seem to play an important role as determinants of PWS. We suggest that walking at PWS may provide benefits in terms of fat oxidation while optimizing gait stability.
ABSTRACT
Moderate-intensity physical activity is recommended for inactive adults with overweight/obesity (OW/OB). The objective of this study is to determine if differences exist in the selection of moderate intensity between inactive adults with juvenile-onset (JO) and adult-onset (AO) OW/OB. Participants (JO = 18, AO = 20) were stratified by onset and completed two separate 20-minute moderate-intensity exercise sessions on a treadmill and cycle ergometer (randomized order). Multiple linear regression was used to determine whether exercise intensity (average METS, % age-predicted HRmax ), self-reported pleasure or exertion differed by onset, controlling for age and gender. On the treadmill, JO and AO participants selected an average intensity of (mean [SD]) 3.5 (0.9) and 3.7 (0.9) METS, and 64.0 (7.7) and 64.9 (7.5) % of age-predicted HRmax , respectively. On the cycle, JO and AO participants selected an average intensity of 3.3 (0.9) and 3.3 (1.0) METS, and 65.2 (8.8) and 60.7 (7.2) % of age-predicted HRmax . After adjustment, participant intensity selection did not significantly differ by obesity onset when walking or cycling. There were no significant differences in pleasure or perceived exertion by onset, however, perception of exertion was on the high-end of moderate for both the cycle (13.0, 12.5) and treadmill (12.0, 12.1), in JO and AO participants, respectively. Perception of moderate intensity did not differ by obesity onset. Self-selected intensity was at the low end of moderate for walking and cycling.
Subject(s)
Exercise , Physical Exertion , Adult , Cross-Over Studies , Humans , Obesity , PerceptionABSTRACT
A randomized controlled study explored the effects of two intensity-oriented exercise interventions on affect to exercise and physical activity behavior. Inactive retirees finished the 12-week group-based exercise intervention and 3-month telephone follow-up with 27 in self-selected intensity group and 26 in prescribed intensity group. Repeated measures of daily step counts (measured by Yamax pedometers), positive and negative affect to exercise, weight, height, waist circumference, and blood pressure were done at baseline, postintervention, and 3-month follow-up. Increased daily step counts and positive affect, and reduced body mass index, waist circumference, blood pressure of both groups, and negative affect of self-selected intensity group were found at different measuring times. Although self-selected intensity group had no significantly different daily step counts from prescribed intensity group, the former had a more positive and less negative affect to exercise. Findings suggest that future exercise programs use self-selected intensity exercise programs to improve pleasure affect to exercise.
Subject(s)
Exercise Therapy , Health Behavior , Retirement/psychology , Affect , Aged , Body Mass Index , Exercise Therapy/psychology , Female , Humans , Male , Pleasure , Self Report , Surveys and QuestionnairesABSTRACT
O objetivo do presente estudo foi investigar a correlação entre aptidão cardiorrespiratória (ACR) e os parâmetros fisiológicos e perceptuais durante caminhada em ritmo auto-selecionado por mulheres adultas sedentárias. Participaram 41 sujeitos (idade 32,6±8,6 anos), que realizaram inicialmente um teste incremental em esteira, para a determinação dos parâmetros fisiológicos e perceptuais máximos, associados ao limiar ventilatório (LV), e posteriormente um teste de 20 minutos de caminhada em ritmo auto-selecionado. Correlação de Pearson (r) foi empregada para verificar a correlação entre ACR e os parâmetros fisiológicos e perceptuais, utilizando significância de p<0,05. A ACR foi inversamente correlacionada aos valores percentuais dos parâmetros fisiológicos, consumo máximo de oxigênio (%VO2máx; r = -0,77; p<0,01), consumo de oxigênio no LV (%VO2LV; r = -0,57; p<0,01), freqüência cardíaca máxima (%FCmáx; r = -0,50; p<0,01) e freqüência cardíaca no LV (%FCLV; r = -0,66; p<0,01) e diretamente associada ao valor absoluto do consumo de oxigênio (VO2; r = 0,43; p<0,01) durante caminhada em ritmo auto-selecionado. Com relação aos parâmetros perceptuais, a ACR foi inversamente correlacionada à percepção subjetiva de esforço (PSE; r = -0,36; p<0,05). Conclui-se que os sujeitos com menor ACR tendem a auto-selecionar uma maior intensidade de exercício físico apresentando uma maior PSE.
The purpose of this study was to investigate the relationship between cardiorrespiratory fitness (CRF) and physiological and perceptual responses during walking at a self-selected pace in sedentary women. The sample was composed by 41 women with age of 32.6 ± 8.6 years. Subjects participated of an incremental test to determine the maximal physiological and perceptual responses; subjects also participated of a 20 minutes treadmill walking bout at self-selected pace to determine the physiological and perceptual responses. Pearson correlation (r) was used to verify the association between CRF and physiological and perceptual responses during walking, with a level of significance of p<0.05. CRF was inversely associated to percentage of maximal oxygen consumption (%VO2max; r = -0,77; p<0,01), percentage of oxygen consumption at the ventilatory threshold (VT; VO2VT; r = -0,57; p<0,01), percentage of maximal heart rate (HRmax; r = -0,50; p<0,01) and percentage of HR at the VT (HRVT; r = -0,66; p<0,01) (p<0.01) and directly related to maximal oxygen consumption (VO2max; r = 0,43; p<0,01) during walking at a self-selected pace. In summary, the subjects with a lower CRF walked at a higher relative intensity and perceived effort.
