Influence of exercise intensity on time spent at high percentage of maximal oxygen uptake during an intermittent session in young endurance-trained athletes

The purpose of this study was to compare, during a 30s intermittent exercise (IE), the effects of exercise intensity on time spent above 90% \({\dot{\hbox{V}}\hbox{O}}_{{{\rm 2max}}} (t90\,{\dot{\hbox{V}}\hbox{O}}_{{{\rm 2max}}})\) and time spent above 95% \({\dot{\hbox{V}}\hbox{O}}_{{{\rm 2max}}} (t95\,{\dot{\hbox{V}}\hbox{O}}_{{{\rm 2max}}})\) in young endurance trained athletes. We hypothesized that during a 30sIE, an increase in exercise intensity would allow an increase in \(t90\,{\dot{\hbox{V}}\hbox{O}}_{{{\rm 2max}}}\;\hbox{and}\;t95\,{\dot{\hbox{V}}\hbox{O}}_{{{\rm 2max}}}\) due to a decrease in time to achieve 90% or 95% of \({\dot{\hbox{V}}\hbox{O}}_{{{\rm 2max}}}.\) Nine endurance-trained male adolescents took part in three field tests. After determination of their \({\dot{\hbox{V}}\hbox{O}}_{{{\rm 2max}}}\) and maximal aerobic velocity (MAV), they performed, until exhaustion, two intermittent exercise sessions alternating 30s at 100% of MAV (IE₁₀₀) or 110% of MAV (IE₁₁₀) and 30s at 50% of MAV. Mean time to exhaustion (t _lim) values obtained during IE₁₀₀ were significantly longer than during IE₁₁₀ (p < 0.01). Moreover, no significant difference was found in \(\hbox{t}90{\dot{\hbox{V}}\hbox{O}}_{{{\rm 2max}}}\;\hbox{or}\; \hbox{t}95 {\dot{\hbox{V}}\hbox{O}}_{{{\rm 2max}}}\) expressed in absolute or relative (%t _lim) values between IE₁₀₀ and IE₁₁₀. In conclusion, an increased of 10% of exercise intensity during a 30s intermittent exercise model (with active recovery), does not seem to be the most efficient exercise to solicit oxygen uptake to its highest level in young endurance-trained athletes.