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ABSTRACT The purpose of this study was to examine how the maximal fat oxidation rate is affected in two groups of women with different fat mass percentages. Thirty-four women with sedentary behavior (aged 18-25 years) were divided into 2 groups according to their body fat percentage. (<32% of body fat was considered as a threshold following American College Sport Medicine [ACSM] indications). Body fat percentages were assessed by anthropometry, then subjects performed an adapted graded exercise test on a treadmill to determine maximal oxygen consumption and fat oxidation rates during exercise. There were significant differences (p<0.05) in maximal cardiorespiratory capacity (34.4±4.4 vs 30.4±10.4 mL x kg-1 x min-1) and maximal fat oxidation rates (0.39±0.05 vs 0.31±0.06 g x min-1) between the lower risk group when compared to the higher risk group. There was no correlation between body fat percentage (BF%) and fat oxidation rates in both groups. In conclusion, cardiorespiratory capacity and substrate oxidation are different when two groups of women divided by ACSM recommendations are considered and these results could help clinicians and trainers to prevent weight gain and/or promote body fat and body weight loss.
RESUMEN El propósito de este estudio fue examinar el cambio de la tasa de oxidación de grasas en dos grupos de mujeres con diferentes porcentajes de masa grasa. Metodología: Treinta y cuatro mujeres con comportamiento sedentario (edades de 18 a 25 años) fueron divididas en dos grupos de acuerdo con su porcentaje de masa grasa (<32% fue considerado como umbral siguiendo las indicaciones del American College Sport Medicine [ACSM]). El porcentaje de masa grasa fue medido por antropometría y luego los sujetos realizaron una prueba adaptado en trotadora eléctrica para determinar el consumo máximo de oxígeno y las tasas de oxidación durante el ejercicio. Resultados: Existieron significativas (p<0,05) en la capacidad cardiorrespiratoria (34,4±4,4 vs 30,4±10,4 mL x kg-1 x min-1) y máxima tasa de oxidación de grasas (0,39±0,05 vs 0,31±0,06 g x min-1) entre el grupo de menor riesgo cuando se compara con el de mayor riesgo. No hubo correlación entre el porcentaje de masa grasa (BF%) vs oxidación máxima de grasas. Conclusión: la capacidad cardiorespiratoria y la oxidación de sustratos fue diferente cuando dos grupos de mujeres son divididos por las consideraciones de la ACSM.
RESUMO
Objective To investigate the effect of 10-week high-intensity intermittent training(HIIT) and maximum fat oxidation (FATmax)intensity training on body composition of female college students,and explore the difference between the 2 training types.Methods Thirty female college students were divided into an HIIT,an FATmax intensity training(FATmax)and a control(CON)group,each of 10.The HIIT and FATmax groups completed a 10-week high-intensity intermittent training and FATmax intensity continuous training with 90％ VO2 max and FATmax intensity respectively,while the CON group maintained the daily habitual behavior.The body weight,waist circumference,hip circumference and skinfold thickness of the triceps,midaxillary,chest,subscapular,abdomen,suprailiac and thigh were measured before and after the intervention.The body composition was evaluated using the Jackson/ Pollock seven-point method.Results The body max index(BMI),waist circumference,hip circumference and waist-hip ratio(WHR)decreased significantly in HIIT and FATmax groups after the 10-week training(P＜0.05),whereas the waist circumference and WHR of the CON group increased(P＜0.05).The decline rate of BMI,waist circumference,hip circumference and WHR of FATmax and HIIT groups were higher than that of the CON(P＜0.01),but there was no difference between the FATmax and HIIT groups.We further noticed no change in the bodyweight and body composition of the CON group,while a significant decrease in the bodyweight,fat percentage and fat mass (P＜0.001),but a significant increase(P＜0.01)in the lean body mass was observed in the FATmax and HIIT groups after the training.Ten weeks of HIIT significantly decreased the fat percentage and fat mass of the exercise groups compared with CON group(P＜0.05),and the rate of fat loss and lean body mass gain of the HIIT group was significantly higher than the FATmax group(P＜0.05).Moreover,the exercise intervention significantly decreased the skinfold thickness of the FATmax and HIIT groups(P＜0.001),but no changes in the CON group.Before the training,there was no significant difference in skinfold thickness among the three groups.However,after the training,the skinfold thickness of the chest,midaxillary,abdomen,suprailiac and thigh of the HIIT group was lower than CON(P＜0.05),and skinfold thickness of abdomen in HIIT group was lower than FATmax group(P＜0.05).Moreover,the decline rate of the skinfold thickness in the midaxillary,suprailiac,subscapular and thigh of the HIIT group was higher than the FATmax group(P＜0.05).Conclusion Both HITT and FATmax intensity continuous training of ten weeks sgnificantly improve the bodyweight,waist circumference,hip circumference and WHR without significant differences.Moreover,they both are effective in bettering the body composition and subcutaneous fat of female college students,with HITT superior to the FATmax intensity continuous training.