Comparison of perceived exertion ratings during graded peak cycle exercise between cigarette smokers and nonsmokers.

This study compared differentiated Ratings of Perceived Exertion (RPE) for the chest (RPE-Chest) and legs (RPE-Legs) and undifferentiated ratings (RPE-Overall) between cigarette smokers (n = 10) and nonsmokers (n = 10) during graded, peak cycle exercise. Linear regression analyses expressed RPE-Chest, RPE-Leg, and RPE-Overall as a function of VO2 for smokers and nonsmokers. RPE equivalent to 50, 70, and 90% VO2 peak were compared between. Chest, Leg, and Overall RPE were similar at each % VO2 peak. In the combined smokers and nonsmokers, RPE-Chest was lower (p < .05) than the RPE-Overall at each % VO2 peak. RPE-Leg did not differ from RPE-Overall at 50% VO2 peak, but was higher (p < .05) at 70% and 90% VO2 peak. These results validate Assumption 4 for application of the Borg 15-category scale in that this assumption is also valid for differentiated RPE. Smoking did not influence the intensity of differentiated or undifferentiated RPE during graded cycle exercise.

Rating perceived exertion during short duration, very high intensity cycle exercise.

This study compared undifferentiated ratings of perceived exertion (RPE) during short duration, very high intensity cycle exercise using high and low resistance. 30 recreationally trained males (24.2 +/- 2.4 yr.) were memory-anchored to the Borg 15-category scale. The high and low resistance exercises were defined by 30-sec. maximum tests assigned in counterbalanced order, with resistances set before testing during an orientation session. High resistance was 10% of body mass. Low resistance resulted in the same total work as the high resistance over the 30-sec. sessions (+/-5%) but increased pedal rate. RPE was taken at 8, 13, 18, 23, and 28 sec. during the high and the low resistance exercises. Measurements were compared using a 2-way repeated-measures analysis of variance. RPE was significantly greater (p=.005) for the high than the low resistance exercise at each interval. RPE increased when the subjects were required to pedal against a greater resistance and produce the highest forces. These RPE data are consistent with data from both aerobic cycle and resistance exercise. The data suggest that instantaneous force production, not summed work, is a primary determinant of RPE. All of these observations support Cafarelli's theoretical model of effort sense. In conclusion, as an individual generates more force during high resistance exercise than in light resistance exercise, a potential explanation of our results is that the increased motor outflow and corollary sensory signal lead to a greater sense of effort.

Comparison of memory and combined exercise and memory-anchoring procedures on ratings of perceived exertion during short duration, near-peak-intensity cycle ergometer exercise.

The purpose of this study was to compare ratings of perceived exertion (RPE) following memory-anchoring and two different types of combined exercise and memory-anchoring during short duration, near-peak-intensity cycle exercise. Thirty recreationally trained males volunteered to participate. The M group, n = 10, received only verbal instructions prior to the experimental trial. The EM1 group, n = 10, and the EM2 group, n = 10, received the same verbal instructions, but these were administered while participants performed maximal, graded cycle ergometer exercise. The low perceptual anchor was established during light pedaling for both EM1 and EM2. The high perceptual anchor was established during the final stage of the maximal cycle test for EM1 and during a 30-sec. sprint immediately following the final stage of the maximal cycle ergometer testing for EM2. On the experimental trial pedaling at maximal intensity for 30-sec. was against a resistance equal to .10 x body mass (kg) on a cycle ergometer. The Borg 15-category RPE scale was used to record exertional perceptions. RPE was reported at 8, 13, 18, 23, and 28 sec. each trial. Ratings were similar among the three groups. Their linear regression slopes and intercepts were also similar. Memory-anchoring produced similar RPE for two different combined exercise and memory-anchoring procedures. In conclusion, memory-anchoring and combined exercise and memory-anchoring produce similar RPE during high intensity, short duration cycle exercise in young recreationally trained athletes.

Fat patterning of adolescents: Allometry of fatfolds.

The relationship between fatfold thickness and fat mass of 101 male and 66 female adolescents (10-16 yr) was examined with the allometric equation y = bxa . Body composition was assessed by underwater weighing and 5 fatfolds were measured: triceps, subscapular, suprailiac, abdominal, and thigh. Percent body fat ranged from 4.9% to 56.1%. The log of each fatfold thickness was plotted versus the log of fat mass. All the relationships were linear and exhibited monophasic allometry. All the alpha coefficients (slope of the log-log plots) exhibited positive allometry. The prepubescent male and female alphas were similar and had the same pattern. The pattern contrasted the trunk with the extremity fatfolds. No differences (P > .05) were found between the alphas for the pubescent males. The triceps alpha of the pubescent females was less (P < .05) than the subscapular, suprailiac, and abdominal alphas. The thigh, subscapular, suprailiac, and abdominal alphas were not significantly (P > .05) different. In conclusion, the trunk was the predominant site of subcutaneous fat deposition for prepubescents, while pubescents exhibit a more general pattern of fat distribution. © 1992 Wiley-Liss, Inc.

Basal metabolism of obese adolescents: Evidence for energy conservation compared to normal and lean adolescents.

To test if obese adolescents systematically conserve energy, comparisons of basal metabolic rate (BMR) of obese, normal, and lean male and female adolescents were made. Obese had eleevated values by as much as 23% (P ≤ 0.05) expressed as kJ · 24 hr-1 compared to the normal and lean. When indexed to body mass (kJ · kg-BM-1 · hr-1 ), the BMR for the obese was depressed by as much as -53% (P ≤ 0.01), and when indexed to fat free mass (kJ · kg-FFM-1 · hr-1 ) it was depressed by -33% compared to normal and lean adolescents. A "theoretical metabolic rate" (TMR), based on the observed fat free mass, fat mass, and their thermal equivalents, was proposed as a theoretical way to properly index basal metabolism, referenced to body composition. Comparisons of the TMR between the obese, normal, and lean revealed that the obese values were depressed by an average -22% (P ≤ 0.05). In comparison, differences in TMR between the normal and lean males and females were no larger than 8% (ns). It was concluded that since both the observed BMR (expressed relative to body composition), and the derived TMR values were depressed for the obese compared to the normal and lean adolescent, the data suggest an energy saving hypothesis for obese adolescents.