What is the VO2 Decrease before Exhaustion during Constant Load Exercise?

Research Paper Title

VO2 decrease Before Exhaustion During Constant Load Exercise. Role of Respiratory Muscles.

Background

The aim of this study was to analyse the VO2 kinetic during a constant load exercise, to check the existence of a VO2 decrease at the end of this kind of exercise and finally to study the respiratory muscles strength evolution, before and after this kind of exercise.

Methods

Eight endurance trained athletes (20.6 ± 2.7 yrs) performed three field-tests until exhaustion:

  • Firstly a maximal graded test to determine their maximal oxygen uptake (VO2max) and maximal aerobic velocity (MAV); and
  • Secondly two constant velocity exercises on track at 100% (tlim100) and 95% of MAV (tlim95) until exhaustion.

Results

The study outcomes revealed a VO2decrease before the end of exercise for three subjects.

The mean decrease duration was 51.3 ± 13.4 s and represented 8.3 ± 2.1 % of the total exercise duration.

Maximal inspiratory and expiratory pressures (PImax and PEmax), measured before and after exercise were considered as respiratory muscle strength indices and were not significantly different before or after the exercise.

Conclusions

The existence of a VO2 decrease before the end of the exercise, already highlighted in the literature is confirmed.

The results indicated that respiratory muscle fatigue was not explicative for VO2 decrease.

However, further studies are necessary to confirm these results.

Reference

Abderrahman, A.B., Bouguerra, L., Rhibi, F., Cretual, A., Ansari, M., Chebbi, A., & Prioux, J. (2019) VO2 decrease Before Exhaustion During Constant Load Exercise. Role of Respiratory Muscles. The Swedish Journal of Scientific Research. 6(1), pp.1-7.

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