Applying the Critical Velocity Concept to High-Intensity Intermittent Performances in Childrenʼs

Abstract

The knowledge of time to exhaustion (TTE) is an easy way to indicate which exercise duration, at a selected intensity, is acceptable for an individual. However, it is not possible to measure multiple TTE. An alternative is to calculate general models of performance based on the linear relationships between exercise distance to exhaustion (DTE) and TTE. This model allows the measurement of the critical velocity (slope of the relationship), and anaerobic distance capacity (intercept). Knowing this relationship, it is also possible to estimate individual performances over a wide range of distances or time. To date, only adults have been investigated. PURPOSE: This study was designed to investigate if the “critical velocity” concept could be applied high-intensity intermittent exercises in children. METHODS: Eleven 8 to 11-year-old children underwent a maximal graded field test to determine peak oxygen uptake (peakVO2) and maximal aerobic velocity (MAV). During the three following sessions, they randomly performed three intermittent runs (120%, 130%, and 140% of MAV) until exhaustion. Intermittent exercises consisted of repeated 15-s runs each one separated by a 15-s passive recovery interval. DTE versus TTE relationships was calculated to determine intermittent critical velocities (CVi). RESULTS: Values for peakVO2, MAV, and CVi were 45.8±5.3 ml.kg-1.min-1, 10.5±1.0 km.h-1, and 11.4±1.2 km.h-1 respectively. Mean values for TTE were 421±121s at 120%of MAV, 233±57s at 130% of MAV, and 136±34s at 140% of MAV. The mean for individual coefficients of determination between DTE and TTE was 0.998±0.003 (0.991<r2<1.0, 0.002<p<0.060). A significant relationship was found for means values between DTE and TTE: r2=0.99 (p<0.05): DTE=3.16TTE+137. Significant relationships were found between peakVO2, CVi (r2=0.47, p<0.05) and MAV(r2=0.70, p<0.001). CONCLUSION: The critical velocity model can successfully be used in children performing short high-intensity intermittent exercises. CVi was significantly related to peakVO2 but explained only 47% of its variance.