title: Adherence to exercise prescriptions: effects of prescribing moderate versus higher levels of intensity and frequency. Objectively measured physical activity is associated with parameters of bone in 70-year-old men and women. Objectively measured light and moderate-to-vigorous physical activity is associated with lower depression levels among older US adults Effect of the volume and intensity of exercise training on insulin sensitivity. Effects of moderate- and intermittent low-intensity exercise on postprandial lipemia. Minimum amount of physical activity for reduced mortality and extended life expectancy: a prospective cohort study Effects of the amount of exercise on body weight, body composition, and measures of central obesity: STRRIDE--a randomized controlled study. The Finnish Diabetes Prevention Study (DPS): Lifestyle intervention and 3-year results on diet and physical activity. Duration of exercise as a key determinant of improvement in insulin sensitivity in type 2 diabetes patients. Light physical activity determined by a motion sensor decreases insulin resistance, improves lipid homeostasis and reduces visceral fat in high-risk subjects: PreDiabEx study RCT Objective measures of activity level and mortality in older men. Effects of the amount and intensity of exercise on plasma lipoproteins. Effects of pre-exercise ingestion of carbohydrate on glycaemic and insulinaemic responses during subsequent exercise at differing intensities Postpartum exercise regardless of intensity improves chronic disease risk factors. Reduction in the incidence of type 2 diabetes with lifestyle intervention or metformin. Slow postmeal walking reduces postprandial glycemia in middle-aged women. Women walking for health and fitness. How much is enough? Breaking up prolonged sitting with light-intensity walking improves postprandial glycemia, but breaking up sitting with standing does not.
abstract: Sedentary adults ( N = 379 ) were r and omly assigned in a 2 x 2 design to walk 30 min per day at a frequency of either 3 - 4 or 5 - 7 days per week , at an intensity of either 45%-55 % or 65%-75 % of maximum heart rate reserve . Analyses of exercise accumulated over 6 months showed greater amounts completed in the higher frequency ( p = .0001 ) and moderate intensity ( p = .021 ) conditions . Analyses of percentage of prescribed exercise completed showed greater adherence in the moderate intensity(p = .02 ) condition . Prescribing a higher frequency increased the accumulation of exercise without a decline in adherence , whereas prescribing a higher intensity decreased adherence and result ed in the completion of less exercise As the world 's population ages , the occurrence of osteoporosis-related fractures is projected to increase . Low areal bone mineral density ( aBMD ) , a well-known risk factor for fractures , may be influenced by physical activity ( PA ) . In this cross-sectional study , we aim ed to investigate potential associations between objective measures of PA and bone properties , in a population -based cohort of 1228 70-year-old men and women . We measured volumetric BMD ( vBMD , mg/cm(3 ) ) together with cross-sectional area ( CSA , mm(2 ) ) by peripheral quantitative computed tomography at sites located 4 % and 66 % in the distal-proximal trajectory at the tibia and radius . We also measured aBMD ( g/cm(2 ) ) by dual energy X-ray absorptiometry at the femoral neck , lumbar spine ( L1-L4 ) and radius . Participants wore triaxial accelerometers for 7 consecutive days to obtain objective estimates of PA . The intensity of the objective PA was divided into light ( 100 - 1951 counts/min [ CPM ] ) , moderate ( 1952 - 5724 cpm ) and vigorous ( ≥ 5725 cpm ) . Maximal accelerations for the anterior-posterior ( z ) , medio-lateral ( x ) , and vertical ( y ) axes were also separately assessed . Associations were investigated using bivariate correlations and multiple linear regression , adjusted for height , weight and sex . Vigorous PA showed the strongest association with femoral neck aBMD ( β=0.09 , p<0.001 ) , while both moderate and vigorous PAs were associated with cortical area and trabecular vBMD in the weight-bearing tibia ( all p<0.05 ) . Peak vertical accelerations were associated significantly with cortical area ( β=0.09 , p<0.001 ) and trabecular vBMD ( β=0.09 , p=0.001 ) of the tibia , whereas peak anterior-posterior accelerations showed no correlation with these properties . No positive association was found between objective ly measured PA and bone parameters of the radius . In conclusion , vertical accelerations and moderate to vigorous PA  independently predict bone properties , especially in the weight-bearing tibia , in 70-year-old men and women Objectives : We have a limited underst and ing of the epidemiological association between objective ly measured physical activity and  depression among older adults . Therefore , the purpose of this study was to examine the association between accelerometer-assessed physical activity and depression symptoms among a nationally representative sample of US older adults . Methods : Data from the 2005–2006 National Health and Nutrition Examination Survey was used . 708 older adults ( 65 + years ) wore an ActiGraph 7164 accelerometer for at least 4 days , and completed data on the study covariates along with depression , as assessed by the Patient Health Question naire-9 . Results : After controlling for age , gender , race-ethnicity , body mass index , marital status , education , comorbidity index , and physical functioning , for every 60-minute increase in light-intensity physical activity , participants were 20 % ( OR = 0.80 ; 95 % CI : 0.67–0.95 ; p = 0.01 ) less likely to be depressed . Moderate-to-vigorous physical activity was also inversely associated with depression ( OR = 0.78 ; 95 % CI : 0.64–0.94 ; p = 0.01 ) . Conclusion : These findings suggest that promoting physical activity , even light-intensity physical activity , may have positive mental health effects  among older adults . Future prospect i ve and experimental studies are warranted Physical activity enhances insulin action in obese/overweight individuals . However , the exercise prescription required for the optimal enhancement is not known . The purpose of this study was to test the hypothesis that exercise training consisting of vigorous-intensity activity would enhance insulin sensitivity more substantially than moderate-intensity activity . Sedentary , overweight/obese subjects ( n = 154 ) were r and omly assigned to either control or an exercise group for 6 mo : 1 ) low-volume/moderate-intensity group [ approximately 12 miles walking/wk at 40 - 55 % peak O2 consumption ( Vo2 peak ) ] , 2 ) low-volume/high-intensity group ( approximately 12 miles jogging/wk at 65 - 80 % Vo2 peak ) , and 3 ) high-volume/high-intensity group ( approximately 20 miles jogging/wk at 65 - 80 % Vo2 peak ) . Training volume ( miles/wk ) was achieved by exercising approximately 115 min/wk ( low-volume/high-intensity group ) or approximately 170 min/wk ( low-volume/moderate-intensity and high-volume/high-intensity groups ) . Insulin action was measured with an insulin sensitivity index ( SI ) from an intravenous glucose tolerance test . In the control group , there was a decrement ( P < 0.05 ) in SI . In contrast , all the exercise groups significantly ( P < 0.05 ) increased SI ; the relative increment in the low-volume/moderate-intensity and high-volume/high-intensity groups ( approximately 85 % ) were greater than in the low-volume/high-intensity group ( approximately 40 % ) . In conclusion , physical activity encompassing a wide range of intensity and volume minimizes the insulin resistance that develops with a sedentary lifestyle . However , an exercise prescription that incorporated approximately 170 min of exercise/wk improved insulin sensitivity more substantially than a program utilizing approximately 115 min of exercise/wk , regardless of exercise intensity and volume . Total exercise duration should thus be considered when design ing training programs with the intent of improving insulin action UNLABELLED The elevation of postpr and ial  plasma triglycerides ( PPTG ) in the blood is an independent risk factor for atherosclerosis . Although acute exercise typically attenuates PPTG , the effect of exercise intensity on PPTG is less well established , particularly in well-controlled conditions for physical activities and diet . PURPOSE We sought to determine the efficacy of exercise at 65 % V˙O2max with an extended sitting time and isoenergetic intermittent walking exercise at a self-selected walking speed ( approximately 25 % V˙O2max ) on PPTG compared with that of a sitting control condition . In a r and omized crossover design , nine healthy young men completed three trials with a > 1-wk interval between trials . After 2 d of activity and diet normalization , participants performed prolonged sitting nonexercise control ( CON ) , prolonged sitting with subsequent 1-h running at 65 % V˙O2max ( MOD ) , or isoenergetic intermittent walking at approximately 25 % V˙O2max ( LOW ) on day 3 . This was followed on day 4 by a 6-h high-fat tolerance test . RESULTS MOD and LOW reduced incremental triglyceride ( TG ) area under the curve ( TG AUCI ) compared with that in CON by 33.6 % ( P < 0.005 ) and 19.8 % ( P < 0.05 ) , respectively . MOD also reduced TG AUCI compared with that in LOW by 17.2 % ( P < 0.03 ) . The reduced TG AUCI in MOD was accompanied by reduced plasma glucose response and enhanced fat oxidation compared with those in LOW and CON ( for all , P < 0.05 ) , respectively . CONCLUSIONS Both MOD and LOW were effective in reducing PPTG compared with CON . However , MOD was more effective in reducing PPTG compared with LOW BACKGROUND The health benefits of leisure-time physical activity are well known , but whether less exercise than the recommended 150 min a week can have life expectancy benefits is unclear . We assessed the health benefits of a range of volumes of physical activity in a Taiwanese population . METHODS In this prospect i ve cohort study , 416,175 individuals ( 199,265 men and 216,910 women ) participated in a st and ard medical screening programme in Taiwan between 1996 and 2008 , with an average follow-up of 8·05 years ( SD 4·21 ) . On the basis of the amount of weekly exercise indicated in a self-administered question naire , participants were placed into one of five categories of exercise volumes : inactive , or low , medium , high , or very high activity . We calculated hazard ratios ( HR ) for mortality risks for every group compared with the inactive group , and calculated life expectancy for every group . FINDINGS Compared with individuals in the inactive group , those in the low-volume activity group , who exercised for an average of 92 min per week ( 95 % CI 71 - 112 ) or 15 min a day ( SD 1·8 ) , had a 14 % reduced risk of all-cause mortality ( 0·86 , 0·81 - 0·91 ) , and had a 3 year longer life expectancy . Every additional 15 min of daily exercise beyond the minimum amount of 15 min a day further reduced all-cause mortality by 4 % ( 95 % CI 2·5 - 7·0 ) and all-cancer mortality by 1 % ( 0·3 - 4·5 ) . These benefits were applicable to all age groups and both sexes , and to those with cardiovascular disease risks . Individuals who were inactive had a 17 % ( HR 1·17 , 95 % CI 1·10 - 1·24 ) increased risk of mortality compared with individuals in the low-volume group . INTERPRETATION 15 min a day or 90 min a week of moderate-intensity exercise might be of benefit , even for individuals at risk of cardiovascular disease . FUNDING Taiwan Department of Health Clinical Trial and Research Center of Excellence and National Health Research Institutes BACKGROUND Obesity is a major health problem due , in part , to physical inactivity . The amount of activity needed to prevent weight gain is unknown . OBJECTIVE To determine the effects of different amounts and intensities of exercise training . DESIGN R and omized controlled trial ( February 1999-July 2002 ) . SETTING AND PARTICIPANTS Sedentary , overweight men and women ( aged 40 - 65 years ) with mild to moderate dyslipidemia were recruited from Durham , NC , and surrounding communities . INTERVENTIONS Eight-month exercise program with 3 groups : ( 1 ) high amount/vigorous intensity ( calorically equivalent to approximately 20 miles [ 32.0 km ] of jogging per week at 65%-80 % peak oxygen consumption ) ; ( 2 ) low amount/vigorous intensity ( equivalent to approximately 12 miles [ 19.2 km ] of jogging per week at 65%-80 % ) , and ( 3 ) low amount/moderate intensity ( equivalent to approximately 12 miles [ 19.2 km ] of walking per week at 40%-55 % ) . Subjects were counseled not to change their diet and were encouraged to maintain body weight . MAIN OUTCOME MEASURES Body weight , body composition ( via skinfolds ) , and waist circumference . RESULTS Of 302 subjects screened , 182 met criteria and were r and omized and 120 completed the study . There was a significant ( P<.05 ) dose-response relationship between amount of exercise and amount of weight loss and fat mass loss . The high-amount/vigorous-intensity group lost significantly more body mass ( in mean [ SD ] kilograms ) and fat mass ( in mean [ SD ] kilograms ) ( -2.9 [ 2.8 ] and -4.8 [ 3.0 ] , respectively ) than the low-amount/moderate-intensity group ( -0.9 [ 1.8 ] and -2.0 [ 2.6 ] , respectively ) , the low-amount/vigorous-intensity group ( -0.6 [ 2.0 ] and -2.5 [ 3.4 ] , respectively ) , and the controls ( + 1.0 [ 2.1 ] and + 0.4 [ 3.0 ] , respectively ) . Both low-amount groups had significantly greater improvements than controls but were not different from each other . Compared with controls , all exercise groups significantly decreased abdominal , minimal waist , and hip circumference measurements . There were no significant changes in dietary intake for any group . CONCLUSIONS In nondieting , overweight subjects , the controls gained weight , both low-amount exercise groups lost weight and fat , and the high-amount group lost more of each in a dose-response manner . These findings strongly suggest that , absent changes in diet , a higher amount of activity is necessary for weight maintenance and that the positive caloric imbalance observed in the overweight controls is small and can be reversed by a modest amount of exercise . Most individuals can accomplish this by walking 30 minutes every day OBJECTIVE To describe the 1 ) lifestyle intervention used in the Finnish Diabetes Prevention Study , 2 ) short- and long-term changes in diet and exercise behavior , and 3 ) effect of the intervention on glucose and lipid metabolism . RESEARCH DESIGN AND METHODS There were 522 middle-aged , overweight subjects with impaired glucose tolerance who were r and omized to either a usual care control group or an intensive lifestyle intervention group .  The control group received general dietary and exercise advice at baseline and had an annual physician 's examination . The subjects in the intervention group received additional individualized dietary counseling from a nutritionist . They were also offered circuit-type resistance training sessions and advised to increase overall physical activity .  The intervention was the most intensive during the first year , followed by a maintenance period . The intervention goals were to reduce body weight , reduce dietary and saturated fat , and increase physical activity and dietary fiber . RESULTS The intervention group showed significantly greater improvement in each intervention goal . After 1 and 3 years , weight reductions were 4.5 and 3.5 kg in the intervention group and 1.0 and 0.9 kg in the control group , respectively . Measures of glycemia and lipemia improved more in the intervention group . CONCLUSIONS The intensive lifestyle intervention produced long-term beneficial changes in diet , physical activity , and clinical and biochemical parameters and reduced diabetes risk . This type of intervention is a feasible option to prevent type 2 diabetes and should be implemented in the primary health care system Exercise duration and intensity are important parameters in exercise prescription and play a major role in improving insulin sensitivity ( including transient and persistent improvement effects following cessation of training ) in patients with type 2 diabetes mellitus ( T2DM ) . However , whether duration or intensity of exercise is the more important factor has yet to be established . Therefore , we aim ed to determine whether exercise prescriptions differing in duration and intensity differ in their ability to aid T2DM patients to retain insulin sensitivity following the conclusion of a period of training . Sedentary T2DM patients ( age 51.2 ± 1.3 years ) were assigned to either a low-intensity ( 50 % VO(2peak ) , n = 27 ) or a high-intensity exercise group ( 75 % VO(2peak ) , n = 28 ) , and followed a 12-week exercise program of 5 sessions/week and 240 kcal/session . Insulin sensitivity ( oral glucose tolerance test , ISI ) was measured when subjects were sedentary and at 16 - 24 h and 15 days after the final training bout . The low-intensity group spent more training time to training per exercise session than the high-intensity group ( 56.1 ± 3.0 min/session vs. 34.3 ± 2.4 min/session ) ( P < 0.01 ) , but the total amount of energy expended was the same . ISI was increased in both groups 16 - 24 h after the final training session , but only the low-intensity group still had elevated ISI 15 days after the cessation of training . These findings suggest that in T2DM patients , the persistent training-induced improvements in insulin sensitivity may be more dependent on exercise duration than exercise intensity in regimens with the same level of energy expenditure Objective : To examine physical activity ( PA ) thresholds affecting glucose , insulin and lipid concentrations and body fat composition in high-risk patients for type 2 diabetes (T2D).Intervention : A total of 113 subjects of both genders having abnormal glucose levels in the oral glucose tolerance test were contacted . A total of 78 subjects with age 58.8±10.4 years and body mass index 31.7±5.3 kg m−2 were r and omly assigned to intervention and control groups . Intervention consisted of a supervised walking ( 60 min three times weekly ) for 3 months . All the subjects received st and ard care for PA and weight reduction and wore an accelerometer during the whole wakeful time . Results : Over 80 % of the daily steps clustered at an acceleration level of 0.3–0.7 g ( 2–3 km h−1 of walking ) and were 5870 in the intervention and 4434 in the control group ( P<0.029 ) . Between 0 and 3 months no significant changes were observed in fasting and 2-h glucose , body weight or maximal oxygen uptake . In contrast , changes in fasting and 2-h insulin ( −3.4 mU l−1 , P=0.035 and −26.6 , P=0.003 , respectively ) , homeostasis model assessment -estimated insulin resistance ( −1.0 , P=0.036 ) , total cholesterol ( −0.55 mmol l−1 , P=0.041 ) , low-density lipoprotein ( LDL ) cholesterol ( −0.36 mmol l−1 , P=0.008 ) and visceral fat area ( −5.5 cm2 , P=0.030 ) were significantly greater in the intervention than in control subjects . The overall effects of PA were analyzed by quartiles of daily steps of all subjects . There were significant reductions in total and LDL cholesterol and visceral fat area between the highest ( daily steps over 6520 ) and the lowest quartile ( 1780–2810 daily steps ) . The changes associated with PA remained significant after adjustments of baseline , sex , age and body weight change . Conclusion : Habitual and structured PAs with the acceleration levels of 0.3–0.7 g and daily steps over 6520 , equivalent to walking at 2–3 km h−1 for 90 min daily , st and ing for the relative PA intensity of 30–35 % of the maximal oxygen uptake , are clinical ly beneficial for overweight/obese and physically inactive individuals with a high risk for T2D OBJECTIVES To examine associations between objective measures of activity level and mortality risk in older men . DESIGN Prospect i ve cohort study . SETTING Six U.S. sites . PARTICIPANTS Men aged 71 and older followed an average of 4.5 years ( N = 2,918 ) .  MEASUREMENTS Time awake spent in sedentary behavior  ( metabolic equivalent ( MET ) level ≤1.50 ) , light activity  ( MET level 1.51 - 2.99 ) , and at least moderate activity  ( MET level ≥3.00 ) measured using an activity monitor worn for 5 days or longer and expressed as quartiles . Deaths were confirmed with death certificates ; cause of death was adjudicated by review of certificates and records . RESULTS During follow-up , 409 ( 14 % ) men died . After multivariable adjustment , comparing Q4 with Q1 , more time spent in sedentary behavior ( Q4 vs Q1 , hazard ratio ( HR ) = 1.51 , 95 % confidence interval ( CI ) = 1.10 - 2.08 ) , less time spent in light activity ( Q1 vs Q4 , HR = 1.54 , 95 % CI = 1.06 - 2.24 ) , and less time spent in at least moderate activity ( Q1 vs Q4 , HR = 1.56 , 95 % CI = 1.09 - 2.25 ) were similarly associated with greater mortality risk primarily due to higher risks of cardiovascular and noncardiovascular , noncancer death . The association between time spent in sedentary behavior and mortality varied according to time spent at higher activity level . More time spent in sedentary behavior was associated with greater risk of death in men spending 1.2 ( median ) h/d or more in at least moderate activity ( Q4 vs Q1 , HR = 2.09 , 95 % CI = 1.26 - 3.49 ) but not in those spending less time ( Q4 vs Q1 , HR = 1.02 , 95 % CI = 0.62 - 1.66 ) ( P = .005 for interaction ) . CONCLUSION In older men exceeding current guidelines on physical activity , more time spent in sedentary behavior is associated with greater mortality risk BACKGROUND Increased physical activity is related to reduced risk of cardiovascular disease , possibly because it leads to improvement in the lipoprotein profile . However , the amount of exercise training required for optimal benefit is unknown . In a prospect i ve , r and omized study , we investigated the effects of the amount and intensity of exercise on lipoproteins . METHODS A total of 111 sedentary , overweight men and women with mild-to-moderate dyslipidemia were r and omly assigned to participate for six months in a control group or for approximately eight months in one of three exercise groups : high-amount-high-intensity exercise , the caloric equivalent of jogging 20 mi ( 32.0 km ) per week at 65 to 80 percent of peak oxygen consumption ; low-amount-high-intensity exercise , the equivalent of jogging 12 mi ( 19.2 km ) per week at 65 to 80 percent of peak oxygen consumption ; or low-amount-moderate-intensity exercise , the equivalent of walking 12 mi per week at 40 to 55 percent of peak oxygen consumption . Subjects were encouraged to maintain their base-line body weight . The 84 subjects who complied with these guidelines served as the basis for the main analysis . Detailed lipoprotein profiling was performed by nuclear magnetic resonance spectroscopy with verification by measurement of cholesterol in lipoprotein subfractions . RESULTS There was a beneficial effect of exercise on a variety of lipid and lipoprotein variables , seen most clearly with the high amount of  high-intensity exercise .  The high amount of exercise result ed in greater improvements than did the lower amounts of exercise ( in 10 of 11 lipoprotein variables ) and was always superior to the control condition ( 11 of 11 variables ) . Both lower-amount exercise groups always had better responses than the control group ( 22 of 22 comparisons ) . CONCLUSIONS The highest amount of weekly exercise , with minimal weight change , had widespread beneficial effects on the lipoprotein profile . The improvements were related to the amount of activity and not to the intensity of exercise or improvement in fitness Abstract . The development of rebound hypoglycaemia has been reported after pre-exercise carbohydrate ( CHO ) ingestion in some studies but not in others . Differences in the experimental design and factors such as the exercise intensity are likely to be responsible for the discrepancies between these studies . Exercise intensity might be a crucial factor since it affects both insulinaemia and glucose uptake . Therefore the aim of the present study was to compare the glycaemic and insulinaemic responses to exercise at different intensities after ingestion of a st and ardized pre-exercise CHO load .  Eight moderately trained subjects consumed 75 g of glucose 45 min prior to 20 min of exercise at 40 % , 65 % or 80 % maximal power output . Blood sample s were collected before glucose ingestion , at 15 min intervals at rest and 5 min intervals during exercise . During exercise , measurements of heart rate and breath-by-breath analysis of expired gas were performed continuously . The trials were performed at [ mean ( SEM ) ] 55 ( 1 ) , 77 ( 1 ) and 90 ( 1 ) percentages maximal oxygen uptake . At the onset of exercise , plasma glucose concentration returned to pre-ingestion levels , while the insulin concentration was more than three times higher than at rest [ on average 57 ( 7 ) compared to 16 ( 1 ) μU·ml–1 ) . During exercise , plasma glucose concentrations decreased during the first 5 min of exercise and then stabilized in all trials at concentrations that would not be considered to be hypoglycaemic . There were no significant differences in glucose or insulin concentrations between the three trials during exercise . These data suggest that the glycaemic response to ingestion of 75 g of CHO 45 min pre-exercise is similar during exercise of different intensities PURPOSE Women who are unable to return to a healthy weight by 6 months postpartum increase their risk factors for the development of chronic disease ( CD ; including metabolic syndrome , obesity , and cardiovascular disease ) . In a prospect i ve r and omized intervention study , we examined the effect of exercise intensity on risk factors for CD in the postpartum . We hypothesized that women receiving an intervention targeting healthy weight loss would have improved CD risk factors compared with women not receiving the intervention . Further , we hypothesized that nutrition control and moderate-intensity exercise would have the greatest improvement in CD risk factors versus low-intensity exercise . METHODS Women were r and omly assigned to a nutrition plus low-intensity ( 30 % HR reserve ; n = 20 ) or moderate-intensity ( 70 % HR reserve ; n = 20 ) exercise intervention group . The program consisted of supervised walking for 45 min , three to four times per week for 16 wk . All women were screened for CD at the beginning ( 7 - 8 wk postpartum ) and at the end ( 23 - 25 wk postpartum ) of the study . A historical control group of 20 sedentary postpartum women was matched by body mass index , age , and parity . RESULTS The low- and moderate-intensity groups lost more body mass ( -4.2 ± 4.0 and -5.0 ± 2.9 kg , respectively ) compared with the control group ( -0.1 ± 3.3 kg , P < 0.01 ) . Plasma low-density lipoprotein was reduced for the low- and moderate-intensity groups ( -0.29 ± 0.21 and -0.28 ± 0.17 mmol · L ) compared with the control group ( 0.03 ± 0.18 mmol · L , P = 0.015 ) . In addition , glucose concentrations were reduced and adiponectin concentrations increased ( P = 0.037 ) , regardless of exercise intensity , although the sedentary controls remained unchanged or at increased risk for CD . CONCLUSIONS Women receiving a postpartum intervention targeting healthy weight loss , regardless of exercise intensity , improved CD risk factors compared with women not receiving the intervention BACKGROUND Type 2 diabetes affects approximately 8 percent of adults in the United States . Some risk factors -- elevated plasma glucose concentrations in the fasting state and after an oral glucose load , overweight , and a sedentary lifestyle -- are potentially reversible . We hypothesized that modifying these factors with a lifestyle-intervention program or the administration of metformin would prevent or delay the development of diabetes . METHODS We r and omly assigned 3234 nondiabetic persons with elevated fasting and post-load plasma glucose concentrations to placebo , metformin ( 850 mg twice daily ) , or a lifestyle-modification program  with the goals of at least a 7 percent weight loss and at least 150 minutes of physical activity per week . The mean age of the participants was 51 years , and the mean body-mass index ( the weight in kilograms divided by the square of the height in meters ) was 34.0 ; 68 percent were women , and 45 percent were members of minority groups . RESULTS The average follow-up was 2.8 years . The incidence of diabetes was 11.0 , 7.8 , and 4.8 cases per 100 person-years in the placebo , metformin , and lifestyle groups , respectively . The lifestyle intervention reduced the incidence by 58 percent ( 95 percent confidence interval , 48 to 66 percent ) and metformin by 31 percent ( 95 percent confidence interval , 17 to 43 percent ) , as compared with placebo ; the lifestyle intervention was significantly more effective than metformin . To prevent one case of diabetes during a period of three years , 6.9 persons would have to participate in the lifestyle-intervention program , and 13.9 would have to receive metformin . CONCLUSIONS Lifestyle changes and treatment with metformin both reduced the incidence of diabetes in persons at high risk . The lifestyle intervention was more effective than metformin Postpr and ial blood glucose concentration is a risk factor for the development of cardiovascular diseases and diabetes , even at states well below hyperglycemic levels . A previous study has shown that postmeal exercise of moderate intensity blunts the blood glucose increase after carbohydrate intake ( Høstmark et al. Prev . Med . 42(5 ) : 369 - 371 ) . The objective of the present study was to examine whether even postmeal slow walking would have a similar effect . Fourteen healthy women aged > 50 years participated in 3 experiments in a r and om crossover design : after a carbohydrate-rich meal , either they were seated ( control experiment ) or they performed slow postmeal walking for 15 min ( W15 ) or 40 min ( W40 ) . Blood glucose concentration was determined prior to the meal ( fasting ) , and at 11 time points throughout each experiment . The W15 trial lowered the blood glucose values during walking and delayed the peak blood glucose value ( p = 0.003 ) . In W40 , the postmeal blood glucose increase during walking was blunted , the peak glucose value was delayed ( p = 0.001 ) , and the incremental area under the 2-h blood glucose curve ( IAUC ) was reduced ( p = 0.014 ) . There was a negative relationship between IAUC and walking time ( p = 0.016 ) . The individual reducing effect of walking on IAUC correlated strongly with IAUC on the control day ( p < 0.001 ) . We conclude that even slow postmeal walking can reduce the blood glucose response to a carbohydrate-rich meal . The magnitude of this effect seems to be related to the duration of walking and to the magnitude of the postpr and ial blood glucose response when resting after a carbohydrate-rich meal OBJECTIVE We studied whether the quantity and quality of walking necessary to decrease the risk of cardiovascular disease among women differed substantially from that required to improve cardiorespiratory fitness . DESIGN A r and omized , controlled , dose-response clinical trial with a follow-up of 24 weeks . SETTING A private , nonprofit biomedical research facility . PARTICIPANTS One hundred two sedentary premenopausal women , 20 to 40 years of age , were r and omized to one of four treatment groups ; 59 completed the study  ( 16 aerobic walkers [ 8.0-km/h group ] , 12 brisk walkers [ 6.4-km/h group ] , 18 strollers [ 4.8-km/h group ] , and 13 sedentary controls ) . Eighty-one percent were white , 17 % black , and 2 % Hispanic . INTERVENTION Intervention groups walked 4.8 km per day , 5 days per week at 8.0 km/h , 6.4 km/h , or 4.8 km/h on a tartan-surfaced , 1.6-km track for 24 weeks . MAIN OUTCOME MEASURES Fitness ( determined by maximal oxygen uptake ) and cardiovascular risk factors ( determined by resting blood pressure and serum lipid and lipoprotein levels ) . RESULTS As compared with controls , maximal oxygen uptake increased significantly ( P less than .0001 ) and in a dose-response manner ( aerobic walkers greater than brisk walkers greater than strollers ) . In contrast , high-density lipoprotein cholesterol concentrations were not dose related and increased significantly ( P less than .05 ) and to the same extent among women who experienced considerable improvements in their physical fitness ( 8.0-km/h group , + 0.08 mmol/L ) and those who had only minimal improvements in fitness ( 4.8-km/h group , + 0.08 mmol/L ) . High-density lipoprotein cholesterol also increased among the 6.4-km/h group , but did not attain statistical significance ( + 0.06 mmol/L ; P = .06 ) . Dietary patterns revealed no significant differences among groups . CONCLUSION Thus , we conclude that vigorous exercise is not necessary for women to obtain meaningful improvements in their lipoprotein profile . Walking at intensities that do not have a major impact on cardiorespiratory fitness may nonetheless produce equally favorable changes in the cardiovascular risk profile OBJECTIVES To explore the effects of breaking up prolonged sitting time with st and ing or light-intensity walking on a range of cardiometabolic risk markers . DESIGN A r and omised three-period , three-treatment acute crossover trial . METHODS Ten non-obese adults took part in three trials : ( 1 ) uninterrupted sitting ; ( 2 ) seated with 2-min bouts of st and ing every 20 min ; and ( 3 ) seated with 2-min bouts of light-intensity walking every 20 min . Two st and ardised test drinks ( total 80.3 carbohydrate , 50 g fat ) were provided after an initial 1-h period of uninterrupted sitting .  Plasma glucose and blood pressure were assessed hourly to calculate area under the curve . Total cholesterol , HDL , and triglycerides were assessed at baseline and 5-h . ANOVAs were used to explore between-trial differences . RESULTS Glucose area under the curve was lower in the activity-break condition compared to the uninterrupted sitting and st and ing-break conditions : mean area under the curve 18.5 ( 95 % CI 17 , 20 ) , 22.0 ( 20.5 , 23.5 ) , and 22.2 ( 20.7 , 23.7 ) mmol L/5-h , respectively , p<0.001 ; no difference between uninterrupted sitting and st and ing-break conditions ( p>0.05 ) . Systolic and diastolic blood pressure area under the curve did not differ significantly between conditions , nor did responses in lipid parameters ( p>0.05 ) . CONCLUSIONS This study suggests that interrupting sitting time with frequent brief bouts of light-intensity activity , but not st and ing , imparts beneficial postpr and ial responses that may enhance cardiometabolic health . These findings may have importance in the design of effective interventions to reduce cardiometabolic disease risk
target: Light-intensity PA was found to be beneficially associated with obesity , markers of lipid and glucose metabolism , and mortality .
  Conclusions Observational evidence that light-intensity PA can confer health benefits is accumulating .
background: Background The health effects of light-intensity physical activity ( PA ) are not well known today .
  Objective We conducted a systematic review to assess the association of accelerometer-measured light-intensity PA with modifiable health outcomes in adults and older adults .