Resting metabolic rate variability as influenced by mouthpiece and noseclip practice procedures

Mouthpiece and noseclip introduction affect resting physiologic function (i.e., hyperventilation, anxiety), which can influence a resting metabolic rate measurement. It also is obvious that practice is required to minimize this influence when such apparatuses are used. However, the type of practice that best minimizes this influence has not been established. To determine the effect of acute and longer term practice on measurement variability of resting metabolic rate, 27 healthy, premenopausal women were randomly assigned to one of three groups: (1) a practice group, involving three 10-minute practice sessions 1 day to 1 week before resting metabolic rate was measured (n = 9); (2) an acclimation group, in which each subject acclimated to the mouthpiece and noseclip for 5 minutes before the resting metabolic rate measurement (n = 8); and (3) a control group (no practice) (n = 10). Resting metabolic rate was measured three times for each subject via a 5-minute oxygen uptake in the early morning (5:00 to 8:30 am) after a 25-minute supine rest. Resting metabolic rate measurements (kJ/day) and intraindividual variance estimates, adjusted for age and weight, were calculated to determine which practice group had the lowest resting metabolic rate measurement and the lowest variability around each individual's repeated resting metabolic rate measures. Of the three averaged resting metabolic rate measures, significantly lower 24-hour energy expenditures were found with the practice (5647 kJ) and acclimation (5550 kJ) groups when compared with those of the control group (6077 kJ) (p < 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)