The independent and combined effects of exercise training and reducing sedentary behavior on cardiometabolic risk factors
2014
Kozey Keadle, Sarah | Lyden, Kate | Staudenmayer, John | Hickey, Amanda | Viskochil, Richard | Braun, Barry | Freedson, Patty S.
This pilot study examined if the combination of exercise training and reducing sedentary time (ST) results in greater changes to health markers than either intervention alone. Fifty-seven overweight/obese participants (19 males/39 females) (mean ± SD; age, 43.6 ± 9.9 years; body mass index (BMI), 35.1 ± 4.6 kg·m–²) completed the 12-week study and were randomly assigned to (i) EX: exercise 5 days·week–¹ for 40 min·session–¹ at moderate intensity; (ii) rST: reduce ST and increase nonexercise physical activity; (iii) EX-rST: combination of EX and rST; and (iv) CON: maintain behavior. Fasting lipids, blood pressure (BP), peak oxygen uptake, BMI, and 2-h oral glucose tolerance tests were completed pre- and post-intervention. EX and EX-rST increased peak oxygen uptake by ∼10% and decreased systolic BP (both p < 0.001). BMI decreased by –3.3% (95% confidence interval: –4.6% to –1.9%) for EX-rST and –2.2% (–3.5% to 0.0%) for EX. EX-rST significantly increased composite insulin-sensitivity index by 17.8% (2.8% to 32.8%) and decreased insulin area under the curve by 19.4% (–31.4% to –7.3%). No other groups improved in insulin action variables. rST group decreased ST by 7% (∼50 min·day–¹); however, BP was the only health-related outcome that improved. EX and EX-rST improved peak oxygen uptake and BMI, providing further evidence that moderate-intensity exercise is beneficial. The within-group analysis provides preliminary evidence that exercising and reducing ST may result in improvements in metabolic biomarkers that are not seen with exercise alone, though between-group differences did not reach statistical significance. Future studies, with larger samples, should examine health-related outcomes resulting from greater reductions in ST over longer intervention periods.
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