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Ventilatory threshold: a useful method to determine aerobic fitness in children?
H Hebestreit1, B Staschen, A Hebestreit
1Universität Kinderklinik, Würzburg, Germany. Hebestreit@mail.uni-wuerzburg.de
Insights
Determining ventilatory threshold (VT) in children is reliable when plotting gas exchange over VO2. This method provides a valid measure of aerobic fitness, even in children born prematurely.
Area of Science:
- Pediatric Exercise Physiology
- Cardiorespiratory Fitness Assessment
- Sports Medicine
Background:
- Accurate assessment of aerobic capacity is crucial for evaluating children's fitness.
- Ventilatory threshold (VT) is a key indicator of aerobic fitness.
- Reliability of VT determination methods in pediatric populations requires validation.
Purpose of the Study:
- To evaluate the reliability and validity of ventilatory threshold (VT) determination in children.
- To compare the accuracy of plotting gas exchange data over time versus over VO2.
- To assess intra- and inter-evaluator consistency in VT measurements.
Main Methods:
- 55 children (35 premature, 20 term-born) aged 6-12 years performed incremental cycling tests.
- Ventilatory data (VE/VO2, VE/VCO2) were plotted over time (X-time) and over VO2 (X-VO2).
- Two blinded evaluators assessed VT twice, 6 weeks apart, for both plotting methods.
Main Results:
- VT determination was successful in 40/55 children using X-time and 45/55 using X-VO2 plots.
- Plotting over VO2 (X-VO2) demonstrated higher intra- and inter-evaluator reliability (ICC 0.92-0.96) compared to plotting over time (X-time) (ICC 0.79-0.98).
- VT showed a strong association with peak oxygen uptake (VO2peak) (r=0.92), confirming its validity as a marker of aerobic capacity.
Conclusions:
- Plotting gas exchange data over VO2 is the preferred method for determining VT in children.
- VT determination is reliable in most children, serving as a valid measure of aerobic fitness.
- This method is applicable for assessing aerobic fitness in diverse pediatric groups, including those born prematurely.
Purpose:
The objective of this study was to assess intra- and inter-evaluator reliability and validity of ventilatory threshold (VT) determination in children.
Methods:
At the age of 6-12 yr, 35 children born prematurely and 20 controls born at term performed an incremental continuous cycling task until volitional fatigue. Fifteen-second averages of VE/VO2, VE/VCO2, and respiratory exchange ratio were plotted 1) over time (X-time) and 2) over VO2 (X-VO2). VCO2 was plotted over VO2 only (X-VO2). Two experienced evaluators, blind to the identity of plots, independently assessed VT from X-time and X-VO2 plots on two occasions, 6 wk apart. Thus, for each of the 55 subjects, four VT values were expected from X-time plots and four from X-VO2 plots (2 evaluators, 2 occasions).
Results:
VT expressed as VO2 in mL x min(-1) could be determined by both evaluators on both occasions in 40/55 children from X-time and in 45/55 children from X-VO2. VT was significantly different between evaluators for X-time plots. Using X-time plots, intraevaluator ICC were 0.88 and 0.98 and interevaluator ICC were 0.82 and 0.79. The respective values for X-VO2 plots were 0.94 and 0.95, and 0.96 and 0.92. Intra- and inter-evaluator reliability of VT determinations tended to be slightly lower in children born prematurely compared with those born at term. There was a close association between VT and VO2peak (r = 0.92).
Conclusion:
Plotting gas exchange data over VO2 is likely to be the method of choice for determining VT. Although a minority of children have uninterpretable X-VO, plots, VT can be reliably interpreted in the remainder. Furthermore, VT is a valid marker of aerobic capacity. Thus, VT is a useful measure of aerobic fitness in children.