3 March 2015, Vol 162, No. 5
TAKE-HOME MESSAGE
- Researchers evaluated 217 patients to determine the impact of exercise amount and intensity on obesity. Patients exercising at low amount and low intensity, at high amount and low intensity, and at high amount and high intensity had greater reduction in waist circumference and body weight than patients not exercising. The high-amount and high-intensity group also had greater reduction in 2-hour glucose levels than the non-exercising group.
- Findings suggest that fixed amounts of exercise offer benefits for obesity independent of intensity.
Abstract
BACKGROUND
Exercise reduces obesity and related glucose tolerance, but whether increasing exercise intensity offers additional benefit at fixed exercise amounts is unknown.
OBJECTIVE
To determine the separate effects of exercise amount and intensity on abdominal obesity and glucose tolerance.
DESIGN
24-week, single-center, parallel-group trial from 2009 to 2013. (ClinicalTrials.gov: NCT00955071).
SETTING
Kingston, Ontario, Canada.
PARTICIPANTS
300 abdominally obese adults.
INTERVENTION
Control (no exercise) (n = 75) or 5 weekly sessions of low-amount, low-intensity exercise (LALI) (180 and 300 kcal/session for women and men, respectively, at 50% of maximum oxygen consumption [V̇o2peak]) (n = 73); high-amount, low-intensity exercise (HALI) (360 and 600 kcal/session, respectively, at 50% of V̇o2peak) (n = 76); or high-amount, high-intensity exercise (HAHI) (360 and 600 kcal/session, respectively, at 75% of V̇o2peak) (n = 76). Daily unsupervised physical activity and sedentary time were measured by accelerometer.
MEASUREMENTS
Waist circumference and 2-hour glucose level (primary outcomes) and cardiorespiratory fitness and measures of insulin action (secondary measurements).
RESULTS
217 participants (72.3%) completed the intervention. Mean exercise time in minutes per session was 31 (SD, 4.4) for LALI, 58 (SD, 7.6) for HALI, and 40 (SD, 6.2) for HAHI. Daily unsupervised physical activity and sedentary time did not change in any exercise group versus control (P > 0.33). After adjustment for age and sex in a linear mixed model, reductions in waist circumference were greater in the LALI (-3.9 cm [95% CI, -5.6 to -2.3 cm]; P < 0.001), HALI (-4.6 cm [CI, -6.2 to -3.0 cm]; P < 0.001), and HAHI (-4.6 cm [CI, -6.3 to -2.9 cm]; P < 0.001) groups than the control group but did not differ among the exercise groups (P > 0.43). After adjustment for covariates, reductions in 2-hour glucose level were greater in the HAHI group (-0.7 mmol/L [-12.5 mg/dL] [CI, -1.3 to -0.1 mmol/L {-23.5 to -1.5 mg/dL}]; P = 0.027) than the control group but did not differ for the LALI or HALI group versus the control group (P > 0.159). Weight loss was greater in all exercise groups than the control group (P < 0.001); however, reduction in body weight did not differ among the exercise groups (P > 0.182).
LIMITATION
The clinical importance of reducing 2-hour glucose level in nondiabetic adults remains undetermined.
CONCLUSION
Fixed amounts of exercise independent of exercise intensity resulted in similar reductions in abdominal obesity. Reduction in 2-hour glucose level was restricted to high-intensity exercise.