Background/Purpose: To determine (a) if there is a metabolic equivalence (MET) difference among healthy weight (n=22), overweight (n=7), and obese (n=15) individuals when engaging in low- or moderate- intensity walking; and (b) if there are MET differences between controlled and perceived speed levels.
Method: 44 participants (21 males, 23 females; age = 31.3 ± 7.7 yr) were classified into three groups based on percentage body fat (%BF) determined by hydrodensitometry. Resting metabolic rate (RMR) was measured via oxygen consumption ( VO2, TrueMax 2400). Randomly ordered exercise protocols were walking on a level treadmill at controlled speeds, low = 2.0mph, 2.5 MET; moderate = 3.5mph, 3.8 MET. After recovery to 110% of resting heart rate, participants estimated the appropriate intensity by walking on the treadmill without speed feedback (this was the perceived condition). VO2 was measured and METs calculated.
Analysis/Results: Overweight and obese participants had higher true MET (walking VO2/participant's RMR) for each walk than healthy/underweight, with and without controlling for %BF, p < 0.005. Overweight and obese participants also showed higher calculated MET (walking VO2/standardized RMR of 3.5 mL/min) than healthy/underweight when controlled for %BF, p < 0.005. MET values were higher when walking at the moderate/controlled speed than walking at moderate/perceived speed, with or without controlling for %BF, p < 0.005.
Conclusions: Exercise intensity, METs, at the same walking speeds are higher for overweight and obese than for healthy/underweight. Individuals, regardless of body weight, will unknowingly self-select for a slower speed than prescribed when asked to walk at a moderate intensity.
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