| Object: To investigate the effect of acute aerobic exercise with same external exerciseworkload on subjects with different fat percent (Fat%), to analyse the relationship betweenfat percent and excess postexercise oxygen consumption (EPOC), and to discuss the possiblemechanism that how Fat%influence EPOC.Methods: Thirty male healthy College students without training experience were dividedinto three groups according to their fat percent, obese group (Fat%>32%, n=10), overweightgroup (24%<Fat%<30%, n=10) and normal groups (Fat%<24%, n=10). To determine therange of workload with45~60%VO2max by an incremental exercise workload experiment,and calculate that the same external exercise workload in this range for all groups was85W.Then all subjects received a bout of acute cycling exercise with85W for40mins. Parametersrelated to physiological function and energy metabolism were determined before, during andpost exercise, which including fat mass (FM) and Fat%, relative and absolute value offat-free mass (FFM and FFM%), magnitude and duration of EPOC, EPOC for each5mins andthe percent of each to total EPOC (which is called P5, P10, P15, P20and P25in turn), heartrate (HR), respiratory exchange ratio (RER) and rating of perceived exertion (RPE).Results:(1) Fat%in obese and overweight group were significantly higher than its innormal group (P<0.01, P<0.01) and Fat%in obese was also higher than its in overweightgroup (P<0.01). No significant difference of FFM in three groups. VO2max, VO2max/BM andVO2max/FFM in obese group were significant lower than those in normal group (P<0.01,P<0.01, P<0.01), and VO2max and VO2max/FFM in overweight group were also significantlower than those in normal group (P<0.01, P<0.01). There was only significant lower level ofVO2max/BM in obese group compared to overweight group (P<0.05). In the aspect of energymetabolism, resting RER were higher (P<0.05, P<0.05), while basal metabolic rate (BMR)were lower (P<0.01, P<0.01) in obese and overweight groups than their in normal group, andBMR/BM in obese group was lower than its in overweight group (P<0.05).(2) The change patterns of HR during exercise were similar in three groups. Theincreased magnitude of HR in the first5mins were relative more, and then HR increasedrelative stable and slow. HR before and each time point during exercise in obese andoverweight group were still higher than those in normal group (P<0.05for before, P<0.01forall during exercise). Only at the end of exercise, HR in obese group was higher than its in overweight group (P<0.05).The change patterns of RPE during exercise were also similar. It gradually increasedover time, and there were no change and slight decreased in1~2time points during exercise.RPE during exercise except the first5mins in obese and overweight group were higher thanthose in normal group (P<0.05for all), and it was same in obese group compared tooverweight group (P<0.05for all).The change patterns of RER during exercise were still similar. There were no clearelevated at the5mins, reached the top level after10mins exercise, and slight decreased at theend of cycling with the values of exceed0.90. Only significant higher level immediately afterexercise in obese group compared to normal group was detected (P<0.05).(3) Total EPOC, excess post-exercise energy metabolism, EPOC/BM, EPOC/FFM andEPOC duration in obese and overweight group were lower than those in normal group(P<0.05for all). Only higher EPOC duration in obese group was found compared tooverweight group (P<0.05). Divided total EPOC into smaller components for each5mins,EPOC for5min and P5in obese and overweight groups were higher than their in normalgroup (P<0.05for both), while the magnitude and percent of EPOC for all resting time pointsin obese and overweight groups were lower than their in normal group (P<0.05for all).Absolute values of oxygen expenditure during exercise, total oxygen expenditure and totalenergy expenditure in obese and overweight groups were higher than their in normal group(P<0.05for all), while relative values of oxygen expenditure during exercise, total oxygenexpenditure, EPOC energy expenditure, and the percent of EPOC to total energy expenditurein obese and overweight groups were higher than their in normal group (P<0.05for all). Onlylower level of relative oxygen expenditure during exercise and total oxygen expenditure inobese group compared to overweight were found.HR of all time points in obese group and overweight groups except20min were higherthan its in normal group (obese vs. normal: P<0.01for all, overweight vs. normal: P<0.01,P<0.01, P<0.05). Duration of recovery in normal was shorter than its in obese group andoverweight groups (P<0.05, P<0.001), and also in obese compared to overweight group(P<0.05). Average speed of recovery in normal was higher than its in obese group andoverweight groups (P<0.01, P<0.05). During recovery, RER decreased quickly to the levelbefore exercise in all groups after10mins. Only higher RER after5min in obese group wasfound compared to normal group (P<0.05).(4) In total subjects, Fat%was positively correlated to P5(r=0.68, P<0.01), while wasnegatively correlated to P15, P20and P25(r=-0.56, P<0.05; r=-0.67, P<0.01; r=-0.68, P<0.01), and also was negatively correlated to EPOC/BM and EPOC duration(r=-0.61,P<0.05; r=-0.78, P<0.01). FM was positively correlated to P5(r=0.65, P<0.01), while wasnegatively correlated to P15, P20and P25(r=-0.55, P<0.05; r=-0.65, P<0.01; r=-0.69,P<0.01), and also was negatively correlated to EPOC/BM and EPOC duration(r=-0.61,P<0.05; r=-0.78, P<0.01). There was no any correlation between FFM and EPOC, whileFFM%was negatively correlated to P5(r=-0.68，P<0.01), while was negatively correlated toP15, P20, P25, EPOC/BM and EPOC duration (r=0.56, P<0.05; r=0.66, P<0.01; r=0.68,P<0.01; r=0.61, P<0.05; r=0.78, P<0.01).Conclusion:(1) Decreased cardiovascular function and aerobic exercise capacity, andmetabolism disturbance to some extent during rest in overweight to obese subjects declinedthe tolerance and adaptation responded to exercise with same external workload.(2) Subjects with different Fat%also produced different physiological response postexercise under same external exercise workload. Obese people showed lower level ofmetabolism during recovery, more rapid EPOC component and higher percent of EPOCcomponent.(3) In the condition of similar FFM, FM and the extent of obese mainly influenced rapidEPOC component, which showed higher percent of rapid EPOC component, relative lowerpercent of prolonged EPOC component, and less total EPOC and shorter EPOC duration.Details mechanism of this phenomenon needed to be clarified by further research. |
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