Omni Scale Perceived Exertion responses in obese and normal weight male adolescents during cycle exercise.

AIM: The Children's OMNI scale of perceived exertion (OMNI Scale) has been validated with children. However, the scale's validity to assess exertional perceptions in obese (OB) adolescents has not been investigated. The aim of this paper was to validate and compare exertional perceptions using the OMNI Scale between OB and normal weight (NW) adolescent males. METHODS: Eighteen OB and 23 NW adolescent males (age: 12-14) participated in a perceptual estimation paradigm with a load incremented cycle ergometer protocol. Heart rate (HR;beats·min-1), oxygen uptake (VO2 mL·min-1 and mL·kg-1·min-1) and rating of perceived exertion (RPE) for the overall body (RPE-O), legs (RPE-L), and chest (RPE-C) were determined at the end of each continuously administered 3-min power output stage as subjects cycled stage-wise incrementally to exhaustion beginning with 4 sub-maximal stages. RESULTS: For OB, 17 completed 4 stages and 3 attained maximal stage 7. For NW, all 18 completed stage 5, and 8 reached maximal stage 7. RPE ranges (i.e. stage 1 to stage 7) for OB and NW were: Stage 1: RPE-O (1.0±1.6, 1.2±0.6), RPE-L (0.9±1.4, 0.9±0.8) and RPE-C (0.9±1.1, 0.9±0.7). Stage 7: RPE-O (7.3±2.3, 8.8±1.4), RPE-L (8.0±2.0, 8.8±1.4) and RPE-C (7.7±2.1, 7.6±3.0). Linear regression for all three RPEs correlated significantly (P<0.001) with HR and VO2 (0.61 to 0.79) for both cohorts. ANOVA indicated no differences between RPE-O and differentiated RPE (RPE-C and RPE-L) at each stage. The RPE responses between OB and NW adolescent males were analyzed by the Bland Altman plot, which indicated significant agreement (95% CI) between the two groups. CONCLUSION: The OMNI Scale is valid for use with 12-14 year-old OB and NW adolescent males. The scale seems to be robust and RPE remained similar for the two cohorts with the same fat free mass but with different fat mass. Hence OMNI scale RPE seems to be able to reflect effort delivered by metabolically active muscle during cycle exercise.

Association of interleukin-15 protein and interleukin-15 receptor genetic variation with resistance exercise training responses.

Interleukin-15 (IL-15) is an anabolic cytokine that is produced in skeletal muscle and directly affects muscle anabolism in animal and in vitro models. The contribution of IL-15 variability in muscle responses to 10 wk of resistance exercise training in young men and women was examined by measuring acute and chronic changes in IL-15 protein in plasma and characterizing genetic variation in the IL-15 receptor-alpha gene (IL15RA). Participants trained 3 days a week at 75% of one repetition maximum, performing three sets (6-10 repetitions) of 13 resistance exercises. Plasma IL-15 protein was significantly increased (P < 0.05) immediately after acute resistance exercise but did not change with training and was not associated with variability in muscle responses with training. A single nucleotide polymorphism in exon 7 of IL15RA was strongly associated with muscle hypertrophy and accounted for 7.1% of the variation in regression modeling. A polymorphism in exon 4 was also independently associated with muscle hypertrophy and accounted for an additional 3.5% of the variation in hypertrophy. These results suggest that IL-15 is an important mediator of muscle mass response to resistance exercise training in humans and that genetic variation in IL15RA accounts for a significant proportion of the variability in this response.

Prediction of 2000 m indoor rowing performance using a 30 s sprint and maximal oxygen uptake.

The aim of this study was to predict indoor rowing performance in 12 competitive female rowers (age 21.3 +/- 3.6 years, height 1.68 +/- 0.54 m, body mass 67.1 +/- 11.7 kg; mean +/- s) using a 30 s rowing sprint, maximal oxygen uptake and the blood lactate response to submaximal rowing. Blood lactate and oxygen uptake (VO2) were measured during a discontinuous graded exercise test on a Concept II rowing ergometer incremented by 25 W for each 2 min stage; the highest VO2 measured during the test was recorded as VO2max (mean = 3.18 +/- 0.35 l.min-1). Peak power (380 +/- 63.2 W) and mean power (368 +/- 60.0 W) were determined using a modified Wingate test protocol on the Concept II rowing ergometer. Rowing performance was based on the results of the 2000 m indoor rowing championship in 1997 (466.8 +/- 12.3 s). Laboratory testing was performed within 3 weeks of the rowing championship. Submitting mean power (Power), the highest and lowest five consecutive sprint power outputs (Maximal and Minimal), percent fatigue in the sprint test (Fatigue), VO2max (l.min-1), VO2max (ml.kg-1.min-1), VO2 at the lactate threshold, power at the lactate threshold (W), maximal lactate concentration, lactate threshold (percent VO2max) and VEmax (l.min-1) to a stepwise multiple regression analysis produced the following model to predict 2000 m rowing performance: Time2000 = -0.163 (Power) -14.213.(VO2max l.min-1) +0.738.(Fatigue) 7.259 (R2 = 0.96, standard error = 2.89). These results indicate that, in the women studied, 75.7% of the variation in 2000 m indoor rowing performance time was predicted by peak power in a rowing Wingate test, while VO2max and fatigue during the Wingate test explained an additional 12.1% and 8.2% of the variance, respectively.

OMNI scale perceived exertion at ventilatory breakpoint in children: response normalized.

PURPOSE: The Children's OMNI Scale of Perceived Exertion was used to identify a response normalized rating of perceived exertion (RPE)-Overall, RPE-Legs, and RPE-Chest that corresponds to the ventilatory breakpoint (Vpt) in 8- to 12-yr-old female and male children. METHODS: Subjects were a priori stratified into two fitness groups on the basis of peak oxygen uptake (VO2 peak): average (A) (41.0-49.0 mL x kg(-1) x min(-1); N = 24) and above average (AA) (50.0-58.0 mL x kg(-1) x min(-1); N = 24). Vpt was determined by a progressive cycle ergometer protocol to VO2 peak. RESULTS: A gender effect was not observed for any descriptive or dependent variable. Mean VO2peak for the A group was 1.72 L x min(-1) and for the AA group 2.04 L x min(-1). Vpt corresponded to 64.0% VO2 peak for A and 74.0% VO2peak for AA. RPE-Overall (mean A and AA, 6.1), RPE-Legs (mean A and AA, 7.2), and RPE-Chest (mean A and AA, 4.5) did not differ between the fitness groups. CONCLUSION: Findings indicated that undifferentiated and differentiated RPE-Vpt were similar between female and male children who varied in VO2peak and Vpt. A comparatively stable RPE-Vpt for 8- to 12-yr-old children that vary in VO2peak and Vpt indicates a group normalized perceptual response.

Children's OMNI scale of perceived exertion: mixed gender and race validation.

PURPOSE: The newly developed Children's OMNI Scale of Perceived Exertion (category range: 0 to 10) was validated using separate cohorts of female and male, African American and white subjects. Each of the four cohorts contained 20 clinically normal, nonobese children, 8-12 yr of age. METHODS: A cross-sectional, perceptual estimation paradigm using a single multi-stage cycle ergometer test protocol was used. Oxygen uptake (VO2; mL x min(-1)), heart rate (HR; beats x min(-1)) and ratings of perceived exertion for the overall body (RPE-Overall), legs (RPE-Legs), and chest (RPE-Chest) were determined at the end of each continuously administered 3-min power output (PO) (i.e., 25, 50, 75, and 100 W) test stage. RESULTS: The range of responses over the four POs for all cohorts was VO2: 290.8 to 1204.0 mL x min(-1); HR: 89.2 to 164.4 beats x min(-1); and RPE-Overall, RPE-Legs, and RPE-Chest: 0.85 to 9.1. First-order correlation and linear regression analyses were performed for each cohort separately and the total sample using a repeated measures paradigm over the four POs. For all correlation/regression paradigms RPE-Overall, RPE-Legs, and RPE-Chest distributed as a positive linear function of both VO2 and HR; r = 0.85 to 0.94; P < 0.01. Differences between RPE-Overall, RPE-Legs, and RPE-Chest were examined with ANOVA for the repeated measures paradigm. RPE-Legs was higher (P < 0.01) than RPE-Chest and RPE-Overall at 25, 50, 75, and 100 W. RPE-Chest did not differ from RPE-Overall at 25 and 50 W but was lower (P < 0.01) than RPE-Overall at 75 and 100 W. CONCLUSION: The psycho-physiological responses provide validity evidence for use of the Children's OMNI Scale over a wide range of dynamic exercise intensities.

Insulin sensitivity in African-American children with and without family history of type 2 diabetes.

OBJECTIVE: African-Americans are at increased risk for type 2 diabetes. We have previously demonstrated that African-American children are hyperinsulinemic and insulin resistant compared with their white American peers. The aim of the present investigation was to assess the impact of family history of type 2 diabetes on insulin sensitivity in African-American children. RESEARCH DESIGN AND METHODS: A total of 13 prepubertal healthy children with negative family history (FH-) and 9 with positive family history (FH+) of type 2 diabetes underwent a 3-h hyperinsulinemic (40 mU x m(-2) x min(-1))-euglycemic clamp study to assess insulin sensitivity. The groups were comparable for age, pubertal status, total body adiposity determined by dual-energy X-ray absorptiometry, abdominal adiposity assessed by computed tomography scan at the level of L4-5 lumbar vertebra, and physical fitness measured by maximal oxygen consumption (VO2max). RESULTS: The FH+, compared with the FH-, group had lower insulin-stimulated glucose disposal (10.9+/-1.2 vs. 14.2+/-0.9 mg x kg(-1) x min(-1), P = 0.035) and lower nonoxidative glucose disposal (5.7+/-0.8 vs. 8.3+/-0.6 mg x kg(-1) x min(-1), P = 0.015), with no differences in rates of glucose oxidation, fat oxidation, or insulin-mediated free fatty acid suppression. Fasting hepatic glucose production assessed with [6,6-2H2]glucose and basal rates of glucose and fat oxidation were not different between the two groups. CONCLUSIONS: These data suggest that in African-American children, family history of type 2 diabetes is a risk factor for insulin resistance. These children manifest important metabolic alterations, including impaired insulin-stimulated total and nonoxidative glucose disposal early in the first decade of life. We propose that this familial tendency, combined with environmental influences, could lead to type 2 diabetes decades later.