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Candace D. Perkins, James M. Pivarnik and Matthew R. Green

Background:

The reliability and validity of the SensorMedics VmaxST was tested.

Methods:

Thirty subjects (age = 24.5 ± 4.0 years, height = 174.8 ± 9.8 cm, weight = 70.3 ± 12.6 kg) performed treadmill exercise on three occasions, twice using the VmaxST and once using the SensorMedics 2900 system. Oxygen consumption (VO2; L/min) and heart rate (HR; beats/min) were measured continuously during three, 6- minute stages: 80 m/min, 0% grade; 94 m/min, 5% grade; and 160 m/min, 0% grade, and VO2max.

Results:

Reliability was high, and measurement error was low for VO2 (Rxx range = 0.97 - 0.99, CI = 0.94 - 1.00, SEM = 0.03 - 0.08 L/min) and HR (Rxx = 0.94 - 0.99, CI = 0.88 - 1.00, SEM = 1.8 - 3.2 beats/min). Validity was high for VO2 (Rxy range = 0.92 - 0.98, CI = 0.84 - 0.99, SEE = 0.08 - 0.21 L/min) and HR (Rxy = 0.97 - 0.99, CI = 0.94 - 1.00, SEE = 0.9 - 1.8 beats/min). Mean differences in VO2 between VmaxST and 2900 were small yet significant (P < 0.001).

Conclusions:

The VmaxST demonstrated excellent reliability and validity for measuring VO2 and HR over several exercise intensities. Small overestimates in VO2 by the VmaxST are countered by low measurement error.

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M. Kathleen Ellis and Lynn A. Darby

This study compared balance and peak oxygen consumption (peak VO2) among hearing, congenital nonhearing, and acquired nonhearing female intercollegiate athletes. Twenty-seven subjects completed two measures of peak VO2 and two measures of balance (static and dynamic). Two pieces of exercise equipment requiring different levels of balance were used: the bicycle ergometer (minimal balance) and the bench-step (maximal balance). Significant differences were found for dynamic balance and for peak VO2 for all subject groups. The significant difference remained among the groups for peak VO2 using the bicycle ergometer when dynamic balance was used as a covariate. There was no significant difference for peak VO2 dependent on type of test when dynamic balance was controlled. The results indicated that dynamic balance affected peak VO2 performance on the bench-step, but not on the bicycle ergometer. These findings suggest that if dynamic balance is required for an assessment of peak VO2, balance should be tested in nonhearing populations.

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Juliane R. Fenster, Patty S. Freedson, Richard A. Washburn and R. Curtis Ellison

The relationship between physical activity measured using the LSI (Large Scale Integrated Activity Monitor), and questionnaire, with physical work capacity 170 (PWC 170) and aerobic capacity (peak V̇O2) was evaluated in 6- to 8-year-old children (n = 18). The mean (± SD) peak V̇O2 was 44.1 ± 5.6 ml • kg−1 • min−1. Peak V̇O2 was not significantly different for children (n = 8) who had completed two treadmill trials (45.4 vs. 43.5 ml • kg−1 • min−1; R = 0.67, p<0.05). The log LSI expressed as counts per hour (M ± SD = 2.1 ±.22 cts/hr) was the only activity method significantly related to peak V̇O2 (r = 0.59, p<0.05). The correlation between peak V̇O2 with the questionnaire was positive but nonsignificant (r = 0.20). PWC 170 was not related to peak V̇O2 (r = 0.21) or the activity variables (r = 0.12 questionnaire; r = 0.18 log LSI). When the group was divided into high and low peak V̇O2 groups (high: M = 48.8 ml • kg−1 • min−1; low: M = 39.5 ml • kg−1 • min−1), the log LSI was able to distinguish significant differences in activity levels (high: 2.23 ±. 19 cts/hr; low: 1.99±.19 cts/hr). This study suggests that activity measured with the LSI and aerobic capacity are related in this sample of 6- to 8-year-old children.

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Neil Armstrong and Melitta McNarry

Peak oxygen uptake (V̇O2) is widely recognized as the criterion measure of young people’s aerobic fitness. Peak V̇O2 in youth has been assessed and documented for over 75 years but the interpretation of peak V̇O2 and its trainability are still shrouded in controversy. Causal mechanisms and their modulation by chronological age, biological maturation and sex remain to be resolved. Furthermore, exercise of the intensity and duration required to determine peak V̇O2 is rarely experienced by most children and adolescents. In sport and in everyday life young people are characterized by intermittent bouts of exercise and rapid changes in exercise intensity. In this context it is the transient kinetics of pulmonary V̇O2 (pV̇O2), not peak V̇O2, which best describe aerobic fitness. There are few rigorously determined and appropriately analyzed data from young people’s pV̇O2 kinetics responses to step changes in exercise intensity. Understanding of the trainability of pV̇O2 kinetics is principally founded on comparative studies of trained and untrained youth and much remains to be elucidated. This paper reviews peak V̇O2, pV̇O2 kinetics, and their trainability in youth. It summarizes “what we know,” identifies significant gaps in our knowledge, raises relevant questions, and indicates avenues for future research.

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Lee N. Cunningham

To compare the physiologic differences between adolescent male and female cross-country runners, 12 male and 12 female high school nonelite distance runners who had competed successfully at the All State 5-km championship cross-country meet were tested in the laboratory. Data were analyzed in relation to maximal oxygen consumption (VO2max), ventilatory threshold (VT), and running economy (RE). Male runners were taller, heavier, had less body fat, and ran faster by 2 minutes and 18 seconds than female runners. Running economy was similar between gender. VO2 at a 215 m•min−1 pace was 46.7 ml•kg−1•min−1 for male runners and 47.8 ml•kg−1•min−1 for female runners. At the VT, males demonstrated a higher VO2 and treadmill velocity than females. Heart rate, percent HR max, and percent VO2 max at the VT were not different between gender. Males demonstrated a higher VO2 max of 74.6 versus 66.1 ml•kg−1•min−1 than female runners. The fractional utilization of VO2 at race pace was not different between males (90%) and females (91%). In conclusion, the primary physiologic determinant for performance differences between nonelite, competitive male and female adolescent distance runners is associated with VO2 max.

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Han C.G. Kemper, Jos W.R. Twisk and Willem van Mechelen

In the Amsterdam Growth And Health Longitudinal Study (AGAHLS), a group of approximately 650 12- to 14-year-old boys and girls was followed in their growth, and development of their health their lifestyle including diet, physical activity and smoking. One of the main interests was the change in their aerobic fitness. From 12 to 36 years of age in total, eight repeated measurements were performed to measure peak oxygen uptake (peak VO2). In this study the data of peak VO2 are revisited and extended: We made use of all collected data as a mixed longitudinal design including cross-sectionally measured subjects as well as longitudinally measured subjects. This led to the availability of 1,194 boys and 1356 girls. With generalized estimating equations (GEE) the longitudinal changes with chronological age and differences between boys and girls were analyzed. Teenage boys and girls increased their peak VO2 (ml/min) significantly (p < .001) until age 14 in girls and until age 17 in boys. However peak VO2 relative to bodyweight (peak VO2/BW) had significantly (p < .001) decreased over the whole age range from 12 to 36 in both sexes. Vigorous physical activity (VPA) also showed a decrease and was significantly (p < .001) related with lower peak VO2/BW (Beta = 0.001). This relation was stronger in boys than in girls. Because at the start of AGAHLS no fast responding metabolic instruments were available, future longitudinal studies about aerobic fitness should include also measurement of VO2 kinetics.

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Benoit Capostagno and Andrew Bosch

This study examined the differences in fat and carbohydrate oxidation during running and cycling at the same relative exercise intensities, with intensity determined in a number of ways. Specifically, exercise intensity was expressed as a percentage of maximum workload (WLmax), maximum oxygen uptake (%VO2max), and maximum heart rate (%HRmax) and as rating of perceived exertion (RPE). Ten male triathletes performed maximal running and cycling trials and subsequently exercised at 60%, 65%, 70%, 75%, and 80% of their WLmax. VO2, HR, RPE, and plasma lactate concentrations were measured during all submaximal trials. Fat and carbohydrate oxidation were calculated from VO2 and VCO2 data. A 2-way ANOVA for repeated measures was used to determine any statistically significant differences between exercise modes. Fat oxidation was shown to be significantly higher in running than in cycling at the same relative intensities expressed as either %WLmax or %VO2max. Neither were there any significant differences in VO2max and HRmax between the 2 exercise modes, nor in submaximal VO2 or RPE between the exercise modes at the same %WLmax. However, heart rate and plasma lactate concentrations were significantly higher when cycling at 60% and 65% and 65–80%WLmax, respectively. In conclusion, fat oxidation is significantly higher during running than during cycling at the same relative intensity expressed as either %WLmax or %VO2max.

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Andrew M. Jones and Mark Burnley

The rate at which VO2 adjusts to the new energy demand following the onset of exercise strongly influences the magnitude of the “O2 defcit” incurred and thus the extent to which muscle and systemic homeostasis is perturbed. Moreover, during continuous high-intensity exercise, there is a progressive loss of muscle contractile efficiency, which is reflected in a “slow component” increase in VO2. The factors that dictate the characteristics of these fast and slow phases of the dynamic response of VO2 following a step change in energy turnover remain obscure. However, it is clear that these features of the VO2 kinetics have the potential to influence the rate of muscle fatigue development and, therefore, to affect sports performance. This commentary outlines the present state of knowledge on the characteristics of, and mechanistic bases to, the VO2 response to exercise of different intensities. Several interventions have been reported to speed the early VO2 kinetics and/or reduce the magnitude of the subsequent VO2 slow component, and the possibility that these might enhance exercise performance is discussed.

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Robert G. McMurray, Joanne S. Harrell, Shrikant I. Bangdiwala, Shibing Deng and Chris Baggett

This study evaluated factors that contribute to the increased energy cost of locomotion in youth. The subjects were 321 8-18-year-old youth, similar dispersed by age and sex. Oxygen uptake (VO2) was measured during rest (REE), running at 8 km · h−1 and cycling at 16 km · h−1, using a COSMED K4b2 metabolic system. Developmental stage was obtained via questionnaire. Stature, body mass, and skinfolds (triceps & subscapular) were measured. Both sexes had similar absolute VO2 (mL · min−1) at rest (p = 0.065) and running (p = 0.084), but the males had a higher VO2 during cycling (p = 0.046). There were no sex differences in relative VO2 (mL · kg−1 · min−1) at rest (p = 0.083); however, the males had a higher VO2 than the females during cycling and running (p £ 0.002). Multiple regression, tested for collinearity, found that absolute VO2 during cycling and running was mostly related to fat-free mass (p = 0.0001). Similar analyses for relative VO2 (mL · kg−1 · min−1) during cycling found that fat-free mass, sex, and skinfolds were significant contributors (p ‡ 0.003). During running the relative VO2 was related to skinfolds, fat-free mass, and resting energy expenditure (p < 0.05). Neither age nor developmental stage was a significant contributor. The results indicate that the VO2 of locomotion is most closely associated with fat-free mass. Thus, to compare youth of varying age or pubertal developmental status, fat-free mass should be taken into consideration.

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Peter A. Hosick, Robert G. McMurray, A.C. Hackney, Claudio L. Battaglini, Terry P. Combs and Joanne S. Harrell

Reports suggest children with high aerobic fitness (VO2max; mL/kg/min) have healthier profiles of TNF-α and IL-6; however, research has not accounted for differences in adiposity between high-fit and low-fit individuals. Thus, this study examined differences in inflammatory markers of obese and normal weight children of different fitness levels, using two different VO2max units: per unit of fat free mass (VO2FFM) or total body mass (VO2kg). Children (n = 124; ages 8–12) were divided into four matched groups; normal weight high-fit (NH), normal weight low-fit (NL), obese high-fit (OH), and obese low-fit (OL). Height, weight, skinfolds, body mass index (BMI), and predicted VO2max were measured and a morning, fasting blood sample taken. IL-6 was elevated in the NL and OL groups compared with the NH group, as well as the OL group compared with the OH group. No differences were found in TNF-α. The relationship between IL-6 or TNF-α and the two units of predicted VO2max did not differ suggesting that either VO2FFM or VO2kg can be used to describe aerobic power when studying inflammation and exercise in youth. The relationship between IL-6 or TNF-α and predicted VO2max, whether expressed per mass or per fat-free mass was similar, suggesting that both can be used to describe aerobic power when studying inflammation and exercise in youth. Given the polar design of this study, this relationship should be confirmed including overweight subjects.