The literature suggests that the oxygen uptake (VO2) response to the onset of moderate-intensity exercise may be both mature from childhood and independent of sex. Yet the cardiorespiratory response to exercise and the metabolic profile of the muscle appear to change with growth and development and to differ between the sexes. The aim of this study was to investigate further changes in the VO2 kinetic response with age and sex. Participants completed a series of no less than four step change transitions, from unloaded pedalling to a constant work rate corresponding to 80% of their previously determined ventilatory threshold. Each participant's breath-by-breath responses were interpolated to 1 s intervals, time aligned and then averaged. A single exponential model that included a time delay was used to analyse the averaged response following phase 1 (15 s). Participants with parameter confidence intervals more than +/- 5 s were removed from the sample; the results for the remaining 13 men and 12 women (age 19-26 years), 12 boys and 11 girls (age 11-12 years) were used for statistical analysis. Children had a significantly shorter time constant than adults, both for males (19.0+/-2.0 and 27.9+/-8.6 s respectively; P<0.01) and females (21.0+/-5.5 and 26.0+/-4.5 s respectively; P<0.05). There were no significant differences in the time constant between the sexes for either adults or children (P>0.05). A significant relationship between the time constant and peak VO2 was found only in adult males (P<0.05). A shorter time constant in children may reflect an enhanced potential for oxidative metabolism.

The purposes of this investigation were to quantify the noise component of child breath-by-breath data, investigate the major determinants of the breath-to-breath noise, and to characterise the noise statistically. Twenty-four healthy children (12 males and 12 females) of mean (SD) age 13.1 (0.3) years completed 25 min of steady-state cycle ergometry at an exercise intensity of 50 W. Ventilatory and gas exchange variables were computed breath-by-breath. The mean (SD) oxygen consumption (VO2) ranged from 0.72 (0.16) to 0.92 (0.26) l x min(-1); mean (SD) carbon dioxide production (VCO2) ranged from 0.67 (0.20) l x min(-1) to 0.85 (0.16) l x min(-1); and mean (SD) minute ventilation ranged from 17.81 (3.54) l x min(-1) to 24.97 (5.63) l x min(-1). The majority of the breath-to-breath noise distributions differed significantly from Gaussian distributions with equivalent mean and SD parameters. The values of the normalised autocorrelation functions indicated a negligible breath-to-breath correlation. Tidal volume accounted for the majority of the VO2 (43%) and VCO2 (49%) variance. The breath-to-breath noise can be explained in terms of variations in the breathing pattern, although the large noise magnitude, together with the relatively small attainable response amplitudes in children reduces the certainty with which ventilatory and gas exchange kinetics can be measured.

exploratory study of cardiac function and oxygen uptake during cycle ergometry in overweight children. Obesity. 2007;15:2673-2682. Objective: Obesity has been proposed to negatively impact cardiac function in overweight (OW) individuals. The relationship between diastolic dysfunction and oxygen uptake (V O 2 ) kinetics is equivocal. This exploratory investigation evaluated the relationship between resting left ventricular function and V O 2 kinetics during cycle ergometry in OW and non-overweight (NO) children and adolescents. Research Methods and Procedures: Fourteen OW (Ͼ85 percentile for BMI for age and gender) children, 10 boys and 4 girls (age, 11.7 Ϯ 1.9 years; body mass, 80.6 Ϯ 45.5 kg) and 10 NO children (4 boys, 6 girls) volunteered to participate in the study (age, 12.5 Ϯ 2.1 years; body mass, 45.8 Ϯ 13.8 kg). Resting cardiovascular structure and function were assessed using spectral Doppler echocardiography. All subjects underwent two sub-maximal exercise stages on a cycle ergometer (3 minutes unloaded and 5 minutes at 50 W, both at a cadence of 50 rpm). Respiratory data were measured on a breath-by-breath basis at both workloads and the mean response time (MRT) was calculated. Results:Analysis of the MRT data demonstrated that there were no significant differences between OW and NO (OW, 52.6 Ϯ 11.7 seconds vs. NO, 45.6 Ϯ 7.4 seconds). Significant correlations (p Ͻ 0.05) were obtained between MRT V O 2 and echocardiographic-derived mitral valve inflow pressure half-time (r ϭ 0.55) and between MRT V O 2 , and mitral valve inflow deceleration time (r ϭ 0.55). Discussion: The evidence from this research suggests a possible link between left ventricular diastolic function at rest and oxygen uptake kinetics during sub-maximal exercise in OW and NO children and adolescents.

Despite the vigorous nature of rock/pop drumming, there are no precise data on the energy expenditure of this activity. The aim of this study was to quantify the energy cost of rock/pop drumming. Fourteen male drummers (mean?SD; age 27?8 yrs.) completed an incremental drumming test to establish the relationship between energy expenditure and heart rate for this activity and a ramped cycle ergometer test to exhaustion as a criterion measure for peak values (oxygen uptake and heart rate). During live concert performance heart rate was continuously measured and used to estimate energy expenditure (from the energy expenditure vs. heart rate data derived from the drumming test). During concert performance, estimated energy expenditure (mean?SD) was 623?168?kcal.h?1 (8.1?2.2 METs) during performances of 38.6?15.6?min, and drummers achieved a peak heart rate of 186?16 b.min?1 During the drumming test participants attained 78.7?8.3% of the cycle ergometer peak oxygen uptake. Rock/pop drumming represents a relatively high-intensity form of physical activity and as such involves significant energy expenditure. Rock/pop drumming should be considered as a viable alternative to more traditional forms of physical activity.

This study assessed age-related changes in power and heart rate in 114 competitive male cyclists age 15–73 years. Participants completed a maximal Kingcycle™ ergometer test with maximal ramped minute power (RMPmax, W) recorded as the highest average power during any 60 s and maximal heart rate (HRmax, beats/min) as the highest value during the test. From age 15 to 29 (n= 38) RMPmaxincreased by 7.2 W/year (r= .53, SE 49 W,p< .05). From age 30 to 73 (n= 78) RMPmaxdeclined by 2.4 W/year (r= –.49, SE 49 W,p< .05). Heart rate decreased across the full age range by 0.66 beats · min–1· year–1(r= –.75, SE 9 beats/min,p< .05). Age accounted for only 25% of the variance in RMPmaxbut 56% in HRmax. RMPmaxwas shown to peak at age 30, then decline with age, whereas HRmaxdeclined across the full age range.