***TASK*** the task is to summarize an input biomedical literature in six sentences 
    ***INPUT*** the input is a biomedical literature 
    ***OUTPUT*** the output is the summary of an input biomedical literature in six sentences 
    ***DOCUMENTATION*** 
    ***EXAMPLES*** 
    Input: Overweight and obesity affects more than 66 % of the adult population and is associated with a variety of chronic diseases . Weight reduction reduces health risks associated with chronic diseases and is therefore encouraged by major health agencies . Guidelines of the National Heart , Lung , and Blood Institute ( NHLBI ) encourage a 10 % reduction in weight , although considerable literature indicates reduction in health risk with 3 % to 5 % reduction in weight . Physical activity ( PA ) is recommended as a component of weight management for prevention of weight gain , for weight loss , and for prevention of weight regain after weight loss . In 2001 , the American College of Sports Medicine ( ACSM ) published a Position St and that recommended a minimum of 150 min wk(-1 ) of moderate-intensity PA for overweight and obese adults to improve health ; however , 200 - 300 min wk(-1 ) was recommended for long-term weight loss . More recent evidence has supported this recommendation and has indicated more PA may be necessary to prevent weight regain after weight loss . To this end , we have reexamined the evidence from 1999 to determine whether there is a level at which PA is effective for prevention of weight gain , for weight loss , and prevention of weight regain . Evidence supports moderate-intensity PA between 150 and 250 min wk(-1 ) to be effective to prevent weight gain .  Moderate-intensity PA between 150 and 250 min wk(-1 ) will provide only modest weight loss . Greater amounts of PA ( > 250 min wk(-1 ) ) have been associated with clinical ly significant weight loss .  Moderate-intensity PA between 150 and 250 min wk(-1 ) will improve weight loss in studies that use moderate diet restriction but not severe diet restriction . Cross-sectional and prospect i ve studies indicate that after weight loss , weight maintenance is improved with PA > 250 min wk(-1 ) . However , no evidence from well- design ed r and omized controlled trials exists to judge the effectiveness of PA for prevention of weight regain after weight loss .  Resistance training does not enhance weight loss but may increase fat-free mass and increase loss of fat mass and is associated with reductions in health risk . Existing evidence indicates that endurance PA or resistance training without weight loss improves health risk . There is inadequate evidence to determine whether PA prevents or attenuates detrimental changes in chronic disease risk during weight gain To examine the effects of acute altitude-induced hypoxia on the hormonal and metabolic response to ingested glucose , 8 young , healthy subjects ( 5 men and 3 women ; age , 26 + /- 2 years ; body mass index , 23.1 + /- 1.0 kg/m(2 ) ) performed 2  r and omized trials in a hypobaric chamber where a 75-g glucose solution was ingested under simulated altitude ( ALT , 4300 m ) or ambient ( AMB , 362 m ) conditions . Plasma glucose , insulin , C-peptide , epinephrine , leptin , and lactate concentrations were measured at baseline and 30 , 60 , 90 , and 120 minutes after glucose ingestion during both trials . Compared with AMB , the plasma glucose response to glucose ingestion was reduced during the ALT trial ( P = .04 ) . There were no differences in the insulin and C-peptide responses between trials or in insulin sensitivity based on the homeostasis model assessment of insulin resistance . Epinephrine and lactate were both elevated during the ALT trial ( P < .05 ) , whereas the plasma leptin response was reduced compared with AMB ( P < .05 ) . The data suggest that the plasma glucose response is suppressed at ALT , but this is not due to insulin per se because insulin and C-peptide levels were similar for both trials . Elevated plasma epinephrine and lactate during ALT are indicative of increased glycogenolysis , which may have masked the magnitude of the reduced glucose response . We conclude that , during acute altitude exposure , there is a rapid metabolic response that is accompanied by a shift in the hormonal milieu that appears to favor increased glucose utilization Training in mild to moderate hypoxia ( 14–17 % O2 in breathing air ) and extended resting in moderate hypoxia ( 9–13 % O2 ) have been shown to have effects in animals and humans on lipid and glucose metabolism , appetite loss , and , in part , on body weight . The causality for these effects is not yet known in detail , and the available data in humans from high-altitude and low-pressure chamber studies are scarce . New technical developments by German companies in the production of artificial climates with normobaric hypoxic conditions in larger rooms at reasonable energy costs allow now to perform hypoxia weight loss studies in obese humans with stable experimental conditions and protocol s with a sham hypoxia control . Thirty-two obese people were recruited for a mild intense training study in normobaric hypoxia ( 15 vol.% O2 ) and normoxia/sham hypoxia ( 20.1 vol.% O2 ) . Twenty of these [ mean age 47.6 years , mean body mass index ( BMI ) 33.1 , 16 m , 4 f ) were willing to follow up on an 8-week , three times per week , 90-min low intense physical exercise in their individual fat burning mode , which has been determined by an exercise testing with spiro-ergometry upfront . The subjects were evenly r and omized into a hypoxia and sham hypoxia group . The difference of the two groups in weight loss and changes in HBa1C values were analyzed before and after the training period . No nutritional diet was applied . Subjects in the hypoxia group in mean lost significantly more weight than in the sham hypoxia group ( Δ1.14 kg vs Δ0.03 kg ; p = 0.026 ) . This result ed in a tendency to reduce the BMI more in the hypoxia group ( p = 0.326 ) . In the mean , there was no HbA1C exceeding normal values ( mean 5.67 and 5.47 % ) , and the HbA1C stayed basically unchanged after the 8-week training . Mild physical exercise three times per week for 90 min in normobaric hypoxia for 8 weeks led to significantly greater weight loss in obese persons  than the exercise in sham hypoxia in this , to our knowledge , first sham hypoxia controlled study The reason for weight loss at high altitudes is largely unknown . To date , studies have been unable to differentiate between weight loss due to hypobaric hypoxia and that related to increased physical exercise . The aim of our study was to examine the effect of hypobaric hypoxia on body weight at high altitude in obese subjects . We investigated 20 male obese subjects ( age 55.7 + /- 4.1 years , BMI 33.7 + /- 1.0 kg/m(2 ) ) .  Body weight , waist circumference , basal metabolic rate ( BMR ) , nutrition protocol s , and objective activity parameters as well as metabolic and cardiovascular parameters , blood gas analysis , leptin , and ghrelin were determined at low altitude ( LA ) ( Munich 530 m , D1 ) , at the beginning and at the end of a 1-week stay at high altitude ( 2,650 m , D7 and D14 ) and 4 weeks after returning to LA ( D42 ) . Although daily pace counting remained stable at high altitude , at D14 and D42 , participants weighed significantly less and had higher BMRs than at D1 . Food intake was decreased at D7 . Basal leptin levels increased significantly at high altitude despite the reduction in body weight . Diastolic blood pressure was significantly lower at D7 , D14 , and D42 compared to D1 . This study shows that  obese subjects lose weight at high altitudes . This may be due to a higher metabolic rate and reduced food intake . Interestingly , leptin levels rise in high altitude despite reduced body weight . Hypobaric hypoxia seems to play a major role , although the physiological mechanisms remain unclear . Weight loss at high altitudes was associated with clinical ly relevant improvements in diastolic blood pressure OBJECTIVE To investigate the relation between the progressive effects of chronic intermittent hypoxia ( CIH )  on cognitive function and the change of cholinergic neuron . METHODS Forty adult male Sprague-Dawley rats were r and omly averagely divided into four groups : control group , CIH 1 week group , CIH 3 week group and CIH 5 week group . The cognitive function was assessed by the Morris Water Maze . The necrosis neurons in prefrontal cortex and hippocampus were observed and counted . The cholin acetyltransferase ( ChAT ) immunostained cells in prefrontal cortex and hippocampus were identified and quantitated . RESULTS The spatial learning and memory impairments progressed from 1 to 5 5 weeks in rats . Compared with the control group , the cognitive impairments in CIH5w group were significant ( P < 0.05 ) . The degeneration or necrosis neurons in prefrontal cortex and hippocampus were significantly increased in CIH rats , and worsen gradually along with the hypoxia . The ChAT immunostained cells in prefrontal cortex and hippocampus were gradually reduced . The ChAT immunostained cells of prefrontal cortex and hippocampus in CIH3w group and CIH5w group were less than that in control group ( P < 0.05 ) . CONCLUSION Chronic intermittent hypoxia induced slowly progressive spatial learning and memory impairments in rats , which maybe associated with the damage of neurons and the reduction of ChAT in prefrontal cortex and hippocampus Background Intermittent normobaric hypoxia training , an alternative to altitude training for athletes , may be beneficial to treat overweight and obesity . The purpose of this study is to investigate whether normobaric hypoxia training combined with low-caloric diet has the additive effect on weight loss compared with normoxia training in obese young adults . Methods Twenty-two subjects ( age 17–25 years , body mass index > 27.5 kg/m2 ) were recruited for a 4-week residential camp of weight loss with low caloric intake , and trained at 60–70 % maximal heart rate of aerobics and 40–50 % of maximal strength of training . They were r and omly assigned to either a normobaric hypoxia ( HT , FiO2 = 16.4–14.5 % ) or normoxia training group ( NT , FiO2 = 21 % ) , and subjects in HT and NT groups experienced weekly 16-h normoxia and 6-h hypoxia or 22-h normoxia training , respectively . Body composition , resting blood pressure ( BP ) and brachial-ankle pulse wave velocity ( baPWV ) were determined before and after the intervention . Results Weight loss was found in HT ( −6.9 kg or −7.0 % , p < 0.01 ) and NT groups ( −4.3 kg or −4.2 % , p < 0.01 ) significantly , and the former lost more weight than the latter ( p < 0.01 ) . Hypoxia training improved systolic BP ( −7.6 % ) and mean BP ( −7.1 % ) significantly ( p < 0.05 ) despite having no effect on baPWV . Conclusion Four weeks of normobaric hypoxia residential training with low caloric diet has an additive improvement on weight loss . It seems that normobaric hypoxia training might be a promising method to treat obesity Objectives : To test the hypothesis that daily acute intermittent hypoxia ( dAIH ) and dAIH combined with overground walking improve walking speed and endurance in persons with chronic incomplete spinal cord injury ( iSCI ) . Methods : Nineteen subjects completed the r and omized , double-blind , placebo-controlled , crossover study . Participants received 15 , 90-second hypoxic exposures ( dAIH , fraction of inspired oxygen [ Fio2 ] = 0.09 ) or daily normoxia ( dSHAM , Fio2 = 0.21 ) at 60-second normoxic intervals on 5 consecutive days ; dAIH was given alone or combined with 30 minutes of overground walking 1 hour later . Walking speed and endurance were quantified using 10-Meter and 6-Minute Walk Tests . The trial is registered at Clinical Trials.gov ( NCT01272349 ) . Results : dAIH improved walking speed and endurance . Ten-Meter Walk time improved with dAIH vs dSHAM after 1 day ( mean difference [ MD ] 3.8 seconds , 95 % confidence interval [ CI ] 1.1–6.5 seconds , p = 0.006 ) and 2 weeks ( MD 3.8 seconds , 95 % CI 0.9–6.7 seconds , p = 0.010 ) . Six-Minute Walk distance increased with combined dAIH + walking vs dSHAM + walking after 5 days ( MD 94.4 m , 95 % CI 17.5–171.3 m , p = 0.017 ) and 1-week follow-up ( MD 97.0 m , 95 % CI 20.1–173.9 m , p = 0.014 ) . dAIH + walking increased walking distance more than dAIH after 1 day ( MD 67.7 m , 95 % CI 1.3–134.1 m , p = 0.046 ) , 5 days ( MD 107.0 m , 95 % CI 40.6–173.4 m , p = 0.002 ) , and  
    Output:
    
Inconclusive findings , however , exist in determining the impact of acute and chronic HC on markers such as triglycerides , cholesterol levels , and fitness capacity .