One repetition maximum prediction models for children using the OMNI RPE Scale.

This investigation developed statistical models to estimate one repetition maximum (1 RM) muscular strength using submaximal ratings of perceived exertion (RPE) as predictor variables. Ten- to 14-year-old girls (n = 35) and boys (n = 35) performed two sets (10 repetitions) of biceps curl (BC) and knee extension (KE) exercise using weights approximating 30% and 50% 1 RM. RPE was assessed during the final repetition of each set using the children's OMNI Resistance Exercise Scale (0-10). Sex-specific statistical models predicted 1 RM using RPE derived from both sets of BC and KE exercises. For both girls and boys, RPE ranged from 3.7 to 6.6 for BC and 4.1 to 7.2 for KE. Group mean 1 RM was (a) girls: BC, 7.44 kg, KE, 13.25 kg and (b) boys: BC, 9.19 kg, KE, 16.24 kg. One repetition maximum prediction models for girls were significant (P < 0.01) for BC (r = 0.87) and KE (r = 0.89). One repetition maximum prediction models for boys were significant (P < 0.01) for BC (r = 0.89) and KE (r = 0.87). The RPE predictors were practical and accurate measures, making the 1 RM models potentially applicable when assessing large numbers of children in short time periods.

Physiological responses during graded treadmill exercise in chemical-resistant personal protective equipment.

BACKGROUND: As the likelihood of terrorist acts increases, prehospital personnel have been forced to train in the proper use of chemical-resistant personal protective equipment (PPE). This protective ensemble has been reported to be physiologically taxing for the wearer, imposing an additional thermal load resulting in hypohydration, hyperthermia, and reduced work time. Victim extrication, the rescue-the-rescuer role of the rapid intervention team and rapid self-extrication, typically requires high-intensity work that can be maintained only for short time intervals. The additional physiological burden imparted by the level C PPE during high-intensity work is unknown. OBJECTIVE: We hypothesized that the added thermal burden resulting from work in PPE would shorten work time and result in a higher core temperature during incremental treadmill exercise. METHOD: In this prospective, crossover, laboratory study, EMS providers (n = 8, 5 male) completed a Bruce treadmill test on two occasions: once in a chemical-resistant coverall and air-purifying respirator (PPE) and once in shorts and t-shirt (CON). Oxygen consumption, vital signs, core and skin temperature, and perceptual measures of exertion, thermal sensation, and comfort were monitored throughout the test. RESULTS: Subjects achieved maximal oxygen consumption and more than 90% of age-predicted maximum heart rate in both conditions. Heart rate, skin temperature, and measures of perceived exertion, comfort, and thermal sensation increased during the treadmill exercise but did not differ between the PPE and CON conditions. Core temperature increased in both the CON and PPE conditions (0.8 +/- 0.5 vs. 0.7 +/- 0.3, p = 0.40). CONCLUSION: High-intensity work in level C PPE is primarily limited by cardiovascular capacity. The thermal burden associated with this short bout of work in PPE (approximately 10 minutes) is not different than high-intensity work in short pants and cotton t-shirt. Consideration should be given to cardiorespiratory fitness when assigning providers to work in chemical-resistant PPE, especially on tasks that require high-intensity work.

Observation of perceived exertion in children using the OMNI pictorial scale.

PURPOSE: Concurrent and construct validity of a kinematic exertional observation procedure was examined for 10- to 14-yr-old female (N = 22) and male (N = 22) healthy children. METHODS: A load-incremented treadmill test protocol employing speed/grade changes every 3 min was used. RPE for the overall body (RPE-Overall), legs (RPE-Legs), and chest (RPE-Chest) were simultaneously estimated by an independent observer and self-rated by a subject during each treadmill stage using the Children's OMNI-Walk/Run Scale. Subjects' HR and oxygen consumption (VO2) were measured during each stage. Concurrent validity was established by correlating the observer's RPE with the subject's HR and VO2. Construct validity was examined by correlating submaximal RPE estimated by the observer with RPE estimated by the subject. RESULTS: The range of responses for the females and males was VO2 = 18.4-43.5 mL x kg(-1) x min(-1), HR = 121-185 bpm, and OMNI Scale RPE- (Overall, -Legs, -Chest) ranging from 1 to 9. Observer RPE (Overall, -Legs, -Chest) for the female and male subjects ranged from 1 to 9. For both female and male groups regression analyses indicated that observer's RPE distributed as a positive function of subject's HR and VO2; r = 0.80-0.91 (P < 0.01). Observer's RPE distributed as a positive function of subject's RPE for both females and males; r = 0.87-0.92 (P < 0.01). CONCLUSION: Results support the validity of a direct kinematic observation procedure to estimate OMNI Scale RPE for female and male children performing treadmill exercise. Exertional observation provides an unobtrusive perceptual estimate of exercise intensity and could be included in standardized physical activity assessments for children.

Evaluation of the SenseWear Pro Armband to assess energy expenditure during exercise.

PURPOSE: To assess the accuracy of the SenseWear Pro Armband for estimating energy expenditure during exercise. METHODS: : Forty subjects (age = 23.2 +/- 3.8 yr; body mass index = 23.8 +/- 3.1 kg x m) performed four exercises (walking, cycling, stepping, arm ergometry) with each exercise lasting 20-30 min and workload increasing at 10-min intervals. Subjects wore the SenseWear Pro Armband on the right arm, and energy expenditure was estimated using proprietary equations developed by the manufacturer. Estimated energy expenditure from the SenseWear Pro Armband was compared with energy expenditure determined from indirect open-circuit calorimetry, which served as the criterion measure. RESULTS: : When a generalized proprietary algorithm was applied to the data, the SenseWear Pro Armband significantly underestimated total energy expenditure by 14.9 +/- 17.5 kcal (6.9 +/- 8.5%) during walking exercise, 32.4 +/- 18.8 kcal (28.9 +/- 13.5%) during cycle ergometry, 28.2 +/- 20.3 kcal (17.7 +/- 11.8%) during stepping exercise, and overestimated total energy expenditure by 21.7 +/- 8.7 kcal (29.3 +/- 13.8%) during arm ergometer exercise (P < or = 0.001). At the request of the investigators, exercise-specific algorithms were developed by the manufacturer and applied to the data that resulted in nonsignificant differences in total energy expenditure between indirect calorimetry and the SenseWear Pro Armband of 4.6 +/- 18.1 kcal (2.8 +/- 9.4%), 0.3 +/- 11.3 kcal (0.9 +/- 10.7%), 2.5 +/- 18.3 kcal (0.9 +/- 11.9%), and 3.2 +/- 8.1 kcal (3.8 +/- 9.9%) for the walk, cycle ergometer, step, and arm ergometer exercises, respectively. CONCLUSIONS: It appears that it is necessary to apply exercise-specific algorithms to the SenseWear Pro Armband to enhance the accuracy of estimating energy expenditure during periods of exercise. When exercise-specific algorithms are used, the SenseWear Pro Armband provides an accurate estimate of energy expenditure when compared to indirect calorimetry during exercise periods examined in this study.