European Journal of Applied Physiology

, Volume 111, Issue 8, pp 1561–1569

Neuromuscular function following prolonged intense self-paced exercise in hot climatic conditions

  • Julien D. Périard
  • Matthew N. Cramer
  • Phillip G. Chapman
  • Corinne Caillaud
  • Martin W. Thompson
Original Article

DOI: 10.1007/s00421-010-1781-3

Cite this article as:
Périard, J.D., Cramer, M.N., Chapman, P.G. et al. Eur J Appl Physiol (2011) 111: 1561. doi:10.1007/s00421-010-1781-3

Abstract

Muscle weakness following constant load exercise under heat stress has been associated with hyperthermia-induced central fatigue. However, evidence of central fatigue influencing intense self-paced exercise in the heat is lacking. The purpose of this investigation was to evaluate force production capacity and central nervous system drive in skeletal muscle pre- and post-cycle ergometer exercise in hot and cool conditions. Nine trained male cyclists performed a 20-s maximal voluntary isometric contraction (MVC) prior to (control) and following a 40-km time trial in hot (35°C) and cool (20°C) conditions. MVC force production and voluntary activation of the knee extensors was evaluated via percutaneous tetanic stimulation. In the cool condition, rectal temperature increased to 39.0°C and reached 39.8°C in the heat (P < 0.01). Following exercise in the hot and cool conditions, peak force declined by ~90 and ~99 N, respectively, compared with control (P < 0.01). Mean force decreased by 15% (hot) and 14% (cool) (P < 0.01 vs. control). Voluntary activation during the post-exercise MVC declined to 93.7% (hot) and 93.9% (cool) (P < 0.05 vs. control). The post-exercise decline in voluntary activation represented ~20% of the decrease in mean force production in both conditions. Therefore, the additional increase in rectal temperature did not exacerbate the loss of force production following self-paced exercise in the heat. The impairment in force production indicates that the fatigue exhibited by the quadriceps is mainly of peripheral origin and a consequence of the prolonged contractile activity associated with exercise.

Keywords

Central fatigueCore temperatureForce productionPerformance

Copyright information

© Springer-Verlag 2010

Authors and Affiliations

  • Julien D. Périard
    • 1
  • Matthew N. Cramer
    • 1
  • Phillip G. Chapman
    • 1
    • 2
  • Corinne Caillaud
    • 1
  • Martin W. Thompson
    • 1
  1. 1.Discipline of Exercise and Sport Science, Faculty of Health SciencesUniversity of SydneyLidcombeAustralia
  2. 2.School of Exercise Science, Faculty of Health SciencesAustralian Catholic UniversityStrathfieldAustralia