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Biomedical subjects

N Blondel

Publications and source records attributed to N Blondel.

7 recordsLinked to original sources
PubMed2003

Time spent at VO2max: a methodological issue.

This study was designed to propose a standardised procedure to determine the time spent at VO2max (tVO2max) based on the VO2max of the day (i. e. the VO2max value measured the day of the test). Ten male subjects first performed a graded field test, followed by a continuous running exercise to exhaustion, at the velocity of the Université de Montréal Track Test (V(UMTT)) plus 1 km x h(-1) (V(UMTT)(+1)). The second test consisted of an exhaustive run at 100 % of V(UMTT), followed by a V(UMTT)(+1) test. Different methods were used to compare time spent at VO2max, based on the VO2max of the graded field test, and time spent at VO2max, based on the VO2max of the day, during an exhaustive run at 100 % of V(UMTT). Results have shown that V(UMTT)(+1) tests were of sufficient intensity and duration to identify the VO2max of the day. Time spent at VO2max ranged from 25 +/- 53 s to 139 +/- 76 s according to the method used. However, the tVO2max method based on the sum of each value higher than 95 % of VO2max of the day appeared more robust than methods based on the time to exhaustion minus time to reach VO2 reference value, or the method based on the sum of values higher than VO2max minus 2.1 ml x kg(-1) x min(-1).

Adult↗
PubMed2002

Effects of high intensity intermittent training on peak VO(2) in prepubertal children.

This study was designed to examine peak VO(2) responses of prepubescent children following a 7-week aerobic training. Twenty-three boys and thirty girls (9.7 +/- 0.8 years) were divided into a high intensity experimental group (HIEG: 20 girls and 13 boys) and a control group (CG: 10 girls and 10 boys). A graded 20-m shuttle run with measurement of gas exchange values was performed prior to and after the 7-week training program. The test consisted of a 3-min run at 7 km x h(-1) to determine energy cost of running, immediately followed by a 20-meter shuttle run test. HIEG had two 30 min-sessions of short intermittent aerobic training per week at velocities ranging from 100 up to 130 % of the maximal aerobic speed. For HIEG, absolute peak VO(2)(9.1 %) and relative to body mass peak VO(2)(8.2 %) increased significantly (p < 0.001); it was unchanged in the CG. Similarly, maximal shuttle run improved significantly in HIEG (5.1 %, p < 0.001). In contrast, there was no significant change for CG. For both groups energy cost of running remained unchanged. These findings show that prepubescent children could significantly increase their peak VO(2) and maximal shuttle velocity with high intensity short intermittent aerobic exercises.

Age Factors↗
PubMed2001

Relationship between run times to exhaustion at 90, 100, 120, and 140% of vVO2max and velocity expressed relatively to critical velocity and maximal velocity.

The aim of the present study was to explain the inter-individual variability in running time to exhaustion (tlim) when running speed was expressed as a percentage of the velocity, associated with maximal oxygen uptake (vVO2max). Indeed for the same percentage of vVO2max the anaerobic contribution to energy supply is different and could be dependent on the critical velocity (Cv) and also on the maximal running velocity (vmax). Ten subjects ran four tlim at 90, 100, 120, and 140% of vVO2max; mean and standard deviation for tlim were 839 +/- 236 s, 357 +/- 110 s, 122 +/- 27 s, and 65 +/- 17s, respectively. Each velocity was then expressed 1) as a percentage of the difference between vVO2max and Cv (%AeSR); 2) as a percentage of the difference between vmax and Cv (%MSR); 3) as a percentage of the difference between vmax and vVO2max (%AnSR). Highest correlations were found between tlim90 and tlim100 and velocity expressed as %MSR (r = -0.82, p < 0.01 and r = -0.75, p < 0.01), and between tlim120 and tlim140 and velocity expressed as %AnSR (r = -0.83, p < 0.01 and r = -0.94, p < 0.001). These results show that the same intensity relative to aerobic contribution did not represent the same absolute intensity for all and could partly explain variability in tlim. Therefore expressing intensity as a percentage of MSR for sub-maximal and maximal velocities and as a percentage of AnSR for supra-maximal velocities allows individual differences in anaerobic work capacity to be taken into account and running times to exhaustion to be predicted accurately.

Adult↗
PubMed2000

Oxygen kinetics and modelling of time to exhaustion whilst running at various velocities at maximal oxygen uptake.

The purpose of this study was to characterise the relationship between running velocity and the time for which a subject can run at maximal oxygen uptake (VO2max), (tlimVO2max). Seven physical education students ran in an incremental test (3-min stages) to determine VO2max and the minimal velocity at which it was elicited (vVO2max). They then performed four all-out running tests on a 200-m indoor track every 2 days in random order. The mean times to exhaustion tlim at 90%, 100%, 120% and 140% vVO2max were 13 min 22 s (SD 4 min 30 s), 5 min 47 s (SD 1 min 50 s), 2 min 11 s (SD 38 s) and 1 min 12 s (SD 18 s), respectively. Five subjects did not reach VO2max in the 90% vVO2max test. All the subjects reached VO2max in the runs at 100% vVO2max. All the subjects, except one, reached VO2max in the runs at 120% vVO2max. Four subjects did not reach VO2max in the 140% vVO2max test. Time to achieve VO2max was always about 50% of the time to exhaustion irrespective of the intensity. The time to exhaustion-velocity relationship was better fitted by a 3- than by a 2-parameter critical power model for running at 90%, 100%, 120%, 140% vVO2max as determined in the previous incremental test. In conclusion, tlimVO2max depended on a balance between the time to attain VO2max and the time to exhaustion tlim. The time to reach VO2max decreased as velocity increased. The tlimVO2max was a bi-phasic function of velocity, with a peak at 100% vVO2max.

Adult↗
PubMed1999

Determination of the velocity associated with the longest time to exhaustion at maximal oxygen uptake.

The so-called velocity associated with VO2max, defined as the minimal velocity which elicits VO2max in an incremental exercise protocol (v(VO2max)), is currently used for training to improve VO2max. However, it is well known that it is not the sole velocity which elicits VO2max and it is possible to achieve VO2max at velocities lower and higher than v(VO2max). The goal of this study was to determine the velocity which allows exercise to be maintained the longest time at v(VO2max). Using the relationship between time to exhaustion at VO2max in the all-out runs at 90%, 100%, 120% and 140% of v(VO2max) and distance run at VO2max, the velocity which elicits the longest time to exhaustion at VO2max (CV') was determined. For the six subjects tested (physical education students), this velocity was not significantly different from v(VO2max) (16.96+/-0.92 km x h(-1) vs 17.22+/-1.12 km x h(-1), P = 0.2 for CV' and v(VO2max), respectively) and these two velocities were correlated (r = 0.88, P = 0.05).

Adult↗
PubMed1999

Validity of the Université de Montréal Track Test to assess the velocity associated with peak oxygen uptake for adolescents.

BACKGROUND: The purpose of the study was to test the ability to determine the velocity associated with peak oxygen uptake for adolescents by means of a simple field test, the Université de Montréal Track Test (UMTT). METHODS: Fifteen adolescents, 13.4 +/- 1.0 years, performed two maximal field tests where oxygen uptake and heart rate were continuously monitored. The first test (graded field test, first stage 8 km.h-1, increment 1.5 km.h-1, duration 3 min) allowed the subjects to reach a steady-state oxygen uptake. Then, the velocity associated with peak oxygen uptake was calculated from the ratio between peak oxygen uptake above resting level to energy cost of running. The calculated velocity was kept as the criterion velocity. For the second test (UMTT, first stage 8 km.h-1; increment 1 km.h-1; duration 2 min), the velocity measured at the last completed stage was retained. RESULTS: The measured peak oxygen uptake for the graded field test (51.8 +/- 6.5 ml.kg-1.min-1) and for the UMTT (51.0 +/- 7.9 ml.kg-1.min-1) were not significantly different. The calculated velocity (12.9 +/- 1.0 km.h-1) and the measured velocity (12.7 +/- 0.9 km.h-1) were not significantly different and were significantly correlated (r = 0.80, p < 0.001). CONCLUSIONS: It was concluded that, for adolescents, the velocity measured at the last completed stage of the UMTT allows a valid estimation of the velocity associated with peak oxygen uptake.

Adolescent↗