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Health‐related fitness values during childhood (from age 11 to 16 years) were analyzed in relation to changes in physical activity level. One hundred fifty‐eight children were monitored over a 4‐year period. Twice a year, they performed six physical fitness tests: standing broad jump, 10 × 5‐meter shuttle run, sit‐and‐reach, handgrip, number of sit‐ups in 30 s, and 20‐m shuttle run. Height was measured four times per year to assess age at peak height velocity. Physical activity was assessed with a self‐administered questionnaire at baseline and at the end of the follow‐up. The physical activity level was defined by the frequency and the time spent in moderate‐to‐vigorous physical activities. Two groups were constituted: regularly active and sedentary. A multiple linear multilevel regression analysis was used to analyze the longitudinal relationships between changes in physical activity and physical fitness levels. Corrections were made for both time‐dependent (time) and time‐independent (sex) variables. Except for flexibility, boys' fitness performances increased more than that for the girls. Positive and significant (P< 0.05) regression coefficients were found with the regularly active for standing broad jump, 20‐m shuttle run, number of sit‐ups, 10 × 5‐m shuttle run in both sexes, and for the girls' sit‐and‐reach performance. Increasing or decreasing physical activity level was not associated with changes in fitness performances over time, except for flexibility for the girls and the 20‐m shuttle run for the boys. From childhood to adolescence, increasing physical activity is not sufficient to be more fit. The children who are stayed the most active were the fittest, particularly the girls. Am. J. Hum. Biol. 18:51–58, 2006. © 2005 Wiley‐Liss, Inc.

The measurement of maximal aerobic speed (MAS) and the prediction of maximal oxygen uptake (VO2 max) by means of field tests were carried out on 17 students studying physical education. The subjects underwent a continuous multi-stage track test (Léger and Boucher, 1980), shuttle test (Léger et al., 1984) and VO2 max measurement on a treadmill.The VO2 max values estimated using the track test (56.8 ± 5.8 ml kg-1 min-1) were not significantly different from the values measured in the treadmill test (56.8 ± 7.1 ml kg-1 min-1), but were higher than those estimated using the shuttle test (51.1 ± 5.9 ml kg-1 min-1). The maximal nature of the tests was checked by measurement of heart rate and lactate concentration, taken within 2 min post-test.The means of the MAS observed in the track test (15.8 ± 1.9 km h-1) and in the treadmill test (15.9 + 2.6 km h-1) were not significantly different (P>0.10). The mean of the shuttle test MAS (13.1 ± 1 km h-1) was significantly lower (P < 0.01) than those of the other tests. However, the MAS of the shuttle test and track test are linked. The equation for linear regression between MAS values in these two tests is MAStrack= 1.81 × MASshuttle - 7.86 (r = 0.91), allowing estimation of one of these MAS values when the other is known. Thus these values may be used within diversified training.

The so-called velocity associated with V?O 2max, defined as the minimal velocity which elicits V?O 2max in an incremental exercise protocol ( v V? O2max), is currently used for training to improve V?O 2max. However, it is well known that it is not the sole velocity which elicits V?O 2max and it is possible to achieve V?O 2max at velocities lower and higher than v V? O2max. The goal of this study was to determine the velocity which allows exercise to be maintained the longest time at V?O 2max. Using the relationship between time to exhaustion at V?O 2max in the all-out runs at 90%, 100%, 120% and 140% of v V? O2max and distance run at V?O 2max, the velocity which elicits the longest time to exhaustion at V?O 2max (CV') was determined. For the six subjects tested (physical education students), this velocity was not significantly different from v V? O2max (16.96?±?0.92?km?·?h -1 vs 17.22?± 1.12?km?·?h -1, P?=?0.2 for CV' and v V? O2max, respectively) and these two velocities were correlated ( r?=?0.88, P?=?0.05).