Context A higher duration and intensity of exercise may improve long-term weight
Objective To compare the effects of different durations and intensities of exercise
on 12-month weight loss and cardiorespiratory fitness.
Design, Setting, and Participants Randomized trial conducted from January 2000 through December 2001 involving
201 sedentary women (mean [SD] age, 37.0 [5.7] years; mean [SD] body mass
index, 32.6 [4.2]) in a university-based weight control program.
Intervention Participants were randomly assigned to 1 of 4 exercise groups (vigorous
intensity/high duration; moderate intensity/high duration; moderate intensity/moderate
duration; or vigorous intensity/moderate duration) based on estimated energy
expenditure (1000 kcal/wk vs 2000 kcal/wk) and exercise intensity (moderate
vs vigorous). All women were instructed to reduce intake of energy to between
1200 and 1500 kcal/d and dietary fat to between 20% and 30% of total energy
Main Outcome Measures Body weight, cardiorespiratory fitness, and exercise participation.
Results After exclusions, 184 of 196 randomized participants completed 12 months
of treatment (94%). In intention-to-treat analysis, mean (SD) weight loss
following 12 months of treatment was statistically significant (P <.001) in all exercise groups (vigorous intensity/high duration
= 8.9 [7.3] kg; moderate intensity/high duration = 8.2 [7.6] kg; moderate
intensity/moderate duration = 6.3 [5.6] kg; vigorous intensity/moderate duration
= 7.0 [6.4] kg), with no significant difference between groups. Mean (SD)
cardiorespiratory fitness levels also increased significantly (P = .04) in all groups (vigorous intensity/high duration = 22.0% [19.9%];
moderate intensity/high duration = 14.9% [18.6%]; moderate intensity/moderate
duration = 13.5% [16.9%]; vigorous intensity/moderate duration = 18.9% [16.9%]),
with no difference between groups. Post hoc analysis revealed that percentage
weight loss at 12 months was associated with the level of physical activity
performed at 6 and 12 months. Women reporting less than 150 min/wk had a mean
(SD) weight loss of 4.7% [6.0%]; inconsistent (other) pattern of physical
activity, 7.0% [6.9%]; 150 min/wk or more, 9.5% [7.9%]; and 200 min/wk or
more of exercise, 13.6% [7.8%].
Conclusions Significant weight loss and improved cardiorespiratory fitness were
achieved through the combination of exercise and diet during 12 months, although
no differences were found based on different exercise durations and intensities
in this group of sedentary, overweight women.