Published in:
Open Access 01-09-2020 | Original Article
Effect of intensive prior exercise on muscle fiber activation, oxygen uptake kinetics, and oxygen uptake plateau occurrence
Published in: European Journal of Applied Physiology | Issue 9/2020
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Purpose
We tested the hypothesis that the described increase in oxygen uptake (\(\dot{V}{\text{O}}_{{2}}\))-plateau incidence following a heavy-severe prior exercise is caused by a steeper increase in \(\dot{V}{\text{O}}_{{2}}\) and muscle fiber activation in the submaximal intensity domain.
Methods
Twenty-one male participants performed a standard ramp test, a \(\dot{V}{\text{O}}_{{{\text{2max}}}}\) verification bout, an unprimed ramp test with an individualized ramp slope and a primed ramp test with the same ramp slope, which was preceded by an intensive exercise at 50% of the difference between gas exchange threshold and maximum workload. Muscle fiber activation was recorded from vastus lateralis, vastus medialis, and gastrocnemius medialis using a surface electromyography (EMG) device in a subgroup of 11 participants. Linear regression analyses were used to calculate the \(\dot{V}{\text{O}}_{{2}}\)-(\(\Delta \dot{V}{\text{O}}_{{2}} /\Delta P\)) and EMG-(∆RMS/∆P) ramp test kinetics.
Results
Twenty out of the 21 participants confirmed their \(\dot{V}{\text{O}}_{{{\text{2max}}}}\) in the verification bout. The \(\dot{V}{\text{O}}_{{2}}\)-plateau incidence in these participants did not differ between the unprimed (n = 8) and primed (n = 7) ramp test (p = 0.500). The \(\Delta \dot{V}{\text{O}}_{{2}} /\Delta P\) was lower in the primed compared to the unprimed ramp test (9.40 ± 0.66 vs. 10.31 ± 0.67 ml min−1 W−1, p < 0.001), whereas the ∆RMS/∆P did not differ between the ramp tests (0.62 ± 0.15 vs. 0.66 ± 0.14% W−1; p = 0.744).
Conclusion
These findings do not support previous studies, which reported an increase in \(\dot{V}{\text{O}}_{{2}}\)-plateau incidence as well as steeper increases in \(\dot{V}{\text{O}}_{{2}}\) and muscle fiber activation in the submaximal intensity domain following a heavy-severe prior exercise.