Effects Of Hypoxic Training And Altitude Training On Body Composition,Resting Metabolism And Exercise Performance Of Overweight And Obese Adolescents

ObjectiveIn the last ten years,whether developed or developing countries,the number of overweight and obesity in children and adolescents increased dramatically,especially in city.It's an independent risk factor of cardiovascular disease,metabolic disease,and may increase the risk of nine different types of cancer at least.“Fatal five quartets”,including hypertension,diabetes,coronary heart disease,hyperlipidemia,and stroke,has been proved associating with obesity.Data published by WHO show that the number of obesity has doubled since 1980;in the world,15 billion aged 20are overweight,2 billion males and 3 billion females are obesity at 2008.The number is continuing to grow.Obesity has become a hidden danger threatening our health.Finding effective ways to control and loss weight has been a serious problem.In addition to drug and surgery,restricting diet and increasing daily energy consumption are two useful aspects in control and loss weight.It's recognized that moderate restricted diet combined with aerobic training is a valid intervention way for weight loss.In the early 70's and 80's of last century,many reports had pointed out that there is a weight loss of climbers during their exploration.The losing magnitude increased with the altitude.Chinese researchers also found a weight reduction phenomenon in 3to 4-weeks'altitude training of athletes.Whether stimulated hypoxia training or altitude training could be used as an effective method for reducing weight by overweight or obesity?In this study,overweight and obese adolescents were selected as the research object,aimed to explore the effects of restricted diet combined with aerobic endurance training in altitude or stimulated hypoxia?²300m?on body weight,body composition,resting metabolic rate,aerobic fitness and anaerobic capacity.And then provide a reference for altitude training and hypoxia training used in the weight loss practice of obesity.Methods50 healthy overweight or obese adolescents aged 16 to 22 years old,living in plain,without cardiovascular diseases,no bad habits such as smoking and drinking,no systematic training history,took part in this research.They were divided into sea-level training group?control group,CG?,hypoxic training group?living high-training high-training low group,HG?and altitude training group?Qinghai Duoba training base,HG?.The intervention last for four weeks.The control group live and exercise in sea-level,exercise six days per week.Hypoxia group sleep in simulated 2300m nomobaric hypoxia from 19:00 to 07:00,training 2 hours at this hypoxia environment in daytime,other arrangements is the same as the control group.Altitude group exercise and live in Qinghai Duoba training base every day.Restricted diet based on resting metabolic rate to ensure the basic energy demand.Daily exercise arrangements:1h-walk?07:30-08:30?,Am 2h-aerobic exercise?10:00-12:00?,Pm 2h-aerobic exercise?15:00-17:00?,both warm-up and warm-down time included in their exercise duration.Exercise forms included brisk walking,jogging,table tennis,badminton,swimming,aerobic dance and bicycle.We monitored heart rate every ten minutes in the process of movement to ensure the exercise intensity is in the target range.Target heart rate intensity was 40%of the heart rate reserve,which determined by the Karvonen equation.One day before and after the experiment,we tested the body weight,body circumference.Body composition was measured by dual energy X ray absorption?GE Lunar Prodigy,soft version:12.2?.Rest metabolic rate was measured at 3hours after dinner by indirect calorimetry?Cosmed K4b²?.Using the 2 step treadmill incremental test evaluated the aerobic fitness?Cosmed K4b²?and recorded the heart rate by ECG?ECG-6951?during their running.The treadmill speed were 4km/h and 6km/h.Every speed lasted 2min.Anaerobic capacity was measured by Wingate method?Monark839E?.The test lasted 30 seconds and the resistance was 7.5%of their body weight.During the anaerobic capacity test,using Sunnto T6C recorded their heart rate.Results1.?1?Compared with pre-training,body weight was significantly reduced in both male and female of three different interventions method.Regardless of gender,weight loss of CG,HG and AG were 9.27kg,8.99kg and 7.86kg,which HG lost significantly more than CG?P<0.05?and HG was significantly lower than CG?P<0.05?.In male,weight loss of HG was obviously more than CG?12.39kg vs 10.65kg,P<0.05?,but there was no notable difference in AG and CG?8.85kg vs 10.65kg?.In female,AG lost much more than HG and CG?7.30kg vs 6.77kg,7.16kg,P<0.05?and no striking difference existed in HG and CG.?2?Whether male or female or overall in three groups,weight loss amplitude showed that HG>CG>AG.Both HG and CG male were marked higher than AG male?11.55%,9.81%vs8.57%,P<0.05?and there was a significantly difference in HG male and CG male.Both HG and CG female were marked higher than AG female?9.09%,8.81%vs 6.99%,P<0.05?,but no significantly difference between HG female and CG female.In three groups,weight loss amplitude of male was bigger than female,but only remarkable difference in HG.?3?There was a significantly difference of weight loss amplitude in every week of three intervention.In the first three weeks,HG male week weight loss amplitude was bigger than CG and AG,while in 1^st week and 3^rd week had notable difference?W₁:4.39%vs 4.04%,2.80%;W₃:3.07%vs 2.20%,2.15%?.However,there was no remarkable difference in different weeks of female.2.After four-weeks intervention,hip circumference and thigh circumference decreased significantly in three groups.?1?Regardless of gender,hip circumference decreased range showed that HG>AG>CG?9.32%,7.83%,6.69%?and there was a notable difference between HG and CG?P<0.05?.Hip circumference decreased range of male showed that HG>CG>AG?10.88%,7.37%,7.26%?and HG was a notable higher than CG and AG?P<0.05?.No significantly difference of hip circumference decreased range in female of three groups.?2?Regardless of gender,thigh circumference loss amplitude showed that CG>HG>AG?5.37%,4.28%,3.59%?and there was a significantly difference between AG and CG?P<0.05?and a significance trend between CG and HG?P=0.07?.3.?1?After 4-week intervention,it showed that someone took an increase but someone decrease in whole body bone mineral content?BMC?.Whole body BMC of CG showed a significant increment?1.95%?.HG and AG also had a little increment but no notable difference.?2?Total BMD increased obviously after 4-weeks training in three groups.The increase amplitude showed that CG>AG>HG?3.01%,2.76%,1.39%?and there was a conspicuous difference between CG and HG?P<0.05?.?3?BMD of arm had a remarkable increase compared with pre-intervention.The amplitude showed CG>AG>HG?17.45%,14.46%,10.65%?.The difference was significant between CG and HG?P<0.05?.However,only AG had an obvious increase after intervention in trunk BMD?1.37%?.The amplitude of them were significant different?CG:0.11%,HG:-0.11%?.4.Whether male or female or all,fat mass?FM?of arm,leg,trunk and whole body took a significant loss after intervention?P<0.05?.?1?Total body FM change percent of AG male was significantly higher than HG and CG male?AG:22.67%vs HG:17.27%,CG:14.65%?.No difference between HG and CG male.In female,it showed that AG>HG>CG?18.13%,15.98%,14.08%?and no difference existed in three interventions.?2?Regardless of gender,trunk FM change percent were AG:18.13%,HG:15.98%and CG:14.08%and there was a notable trend between AG and CG?P-0.08?.In male,trunk FM loss amplitude of AG was significantly higher than HG and CG?25.57%vs 18.21%,15.60%,P<0.05?but no remarkable difference between HG and CG.No outstanding difference of trunk FM loss percent existed in female of three groups?HG:14.19%,AG:13.89%,CG:12.56%?.?3?FM loss range of arm and leg in these groups were bigger,but no marked difference among them.5.Compared the FM loss of different parts to total FM loss in three interventions,we found that trunk>leg>arm in all groups.FM loss of leg to total FM loss in HG was highest?34.94%?.FM loss of trunk to total FM loss in AG?63.18%?was much bigger than others.6.Fat mass of android and gynoid region were decreased significantly after four weeks intervention.?1?Regardless of male or female or all,FM loss in android region showed that AG>HG>CG and the amplitude of AG male was obviously higher than CG male?27.19%vs 20.26%?.FM loss of AG female was significant higher than HG and CG female,however,the difference disappeared in FM loss amplitude.?2?Regardless of male or female,FM loss in gynoid region showed that HG>AG>CG?14.06%,13.60%,12.69%?,but no conspicuous difference in three groups.FM loss amplitude of male in gynoid region showed AG>HG>CG?19.26%,15.87%,14.36%?and the difference between AG and CG male was remarkable?P<0.05?.While,in female,FM loss amplitude of gynoid in CG and HG expressed a significant higher trend than AG?12.85%,12.61%vs 8.94%?and no obvious difference between CG and HG.7.Total FM loss to body weight loss was much more 50%.Regardless of gender,it showed as AG>HG>CG?86.84%,60.47%,58.52%?and the difference between AG and CG or HG were significant?P<0.05?.But no remarkable difference existed between CG and HG.8.?1?Lean soft mass?LSM?of trunk and whole body decreased obviously after intervention in CG and HG,but no significance in AG.It was worthwhile to note that LSM of arm and leg of AG male had a little increase compared with pre-intervention.?2?Whether male or female or all,the LSM loss amplitude showed as CG>HG>AG.Compared with AG male,the LSM loss amplitude of CG was significant bigger?4.72%vs 0.14%,P<0.05?and there was a significance trend between HG and AG?3.85%vs0.14%,P=0.07?.Regardless of gender,LSM loss amplitude of CG and HG were remarkable bigger than AG?4.71%?3.29%vs 1.84%,P<0.05?.9.?1?REE,REE/BSA and REE/kg increased after four-week intervention in all groups and the increase range was expressed as CG>HG>AG,but only significance existed between CG and AG.The incremental amplitude of these indexes showed that CG>AG>HG in male of three groups and there was remarkable difference trend between CG male and HG male.The incremental amplitude of these indexes of female expressed as CG>HG>AG and the difference was significant between CG,HG and AG?P<0.05?,no obvious difference existed between CG and HG.?2?The proportion of fat for energy at rest increased after intervention.Regardless of gender,the growth was expressed as CG>HG>AG and there was a significance trend between CG and AG?41.14%vs 21.92%,P=0.06?.In female,we found that the growth range was expressed as CG>HG>AG and CG increased significantly more than HG and AG?57.61%vs 36.38%,11.54%,P<0.05?,which of HG was remarkable higher than AG?P<0.05?.The growth of male show that AG>HG>CG?40.10%,29.84%,24.67%?,however,there were no conspicuous difference among three groups.10.?1?After four-week experiment,the volume of oxygen uptake under 4km/h and6km/h treadmill of three intervention were all increased in different degree and we found both the volume of carbon dioxide output and the respiratory quotient were decreased.At the same time,heart rate and the proportion of fat for energy during exercise,whether 4km/h or 6km/h,declined in all groups compared with pre-intervention.?2?Regardless of gender,peak power to weight?PP/kg?in Wingate tests increased in different degree and the amplitude could be expressed as AG>HG>CG?16.20%,10.56%,5.59%?.There was a significance trend between AG and CG.Except HG male of PP/kg had a little decline?-1.00%?,others increased more or less especially the HG female?19.56%?and AG male or female?7.50%,22.00%?increased significantly compared with pre-intervention.?3?The instance heart rate after Wingate test in all groups increased obviously.However,the heart rate at 3^rd minute of recovery period decreased significantly compared with pre-training and we found that the decline amplitude of HG and AG were remarkable greater than CG?-19.23%,-18.92%vs-11.68,P<0.05?.Interestingly,3-minute heart rate recovery speed of HG and AG were both significantly higher than CG?66.10%,103.48%vs35.05%,P<0.05?.Conclusion1.Four-week restricted diet combined with aerobic endurance training in sea-level,hypoxia and altitude could reduce body weight of overweight and obese adolescent effectively,especially in male.From the amount and amplitude of weight reduction point,hypoxic training had a better effect than normoxic training,while altitude training didn't show any more effect than normoxic training.2.Four-week restricted diet combined with aerobic endurance training in sea-level,hypoxia and altitude could reduce whole body mass and different parts of body fat mass.Most of the fat loss occurred in trunk,it accounted for 50%⁶0%of total fat loss.Secondly was in leg,it accounted for about 30%of total fat loss.Fat loss to body weight loss after altitude training was significantly higher than normoxic training,which accounted for 87%in altitude training.It suggested that altitude training was helpful to decrease the loss of other composition except for fat.From the perspective of total fat loss volume and amplitude,male training in hypoxia and altitude had better effect than in normoxia,especially training in altitude.When reduced fat mass effectively,altitude training didn't result in obvious changes in lean soft tissue mass.However,hypoxic training and normoxic training led to a remarkable loss in lean soft tissue mass,especially in normoxic training.All of these intervention methods were helpful to improve bone heath of overweight and obese adolescents.The improvement of normoxia training was much bigger than others.There was some difference of BMD change in different parts of their body.3.All of these intervention methods were useful to increase the rest energy expenditure and its related indexes,which increased most in normoxic training.Fat for energy at rest increased in all three methods,which of female increased most in normoxia but of male was altitude training.4.For overweight and obese adolescents,four-week restricted diet combined with aerobic endurance training could result in increment of fat oxidation during low intensity exercise and some improvement of aerobic fitness,which was greater in hypoxic training and altitude training.It also led to some improvement of anaerobic capacity,especially female training in hypoxia and altitude.