Fatigue from cycling…is it in your head?

When an athlete gets tired we usually think that it is solely because of muscle fatigue. New research from the Nicholas Institute of Sports Medicine and Athletic Trauma (NISMAT), however, suggests that our brain can fatigue as well (Central Fatigue). In a study by Kremenic et al, trained cyclists rode for 2 hours at ~66% of VO2 max with 5, 1-min sprints interspersed followed by a 3-km time trial at the end of the cycling bout. Quadriceps strength testing was performed before and after cycling to record the following: 1) Maximum voluntary contraction (MVC), 2) MVC with superimposed magnetic stimulation to measure the central activation ratio (CAR), 3) Femoral nerve stimulation alone. The results demonstrated that the MVC declined by 22% indicating fatigue. Force elicited by the magnetic stimulation alone decreased 17% and the CAR decreased from 83% before exercise to 71% after exercise indicating a loss of central drive (brain fatigue).

Translation: Trained cyclists demonstrate significant central fatigue during prolonged cycling. Both central and peripheral mechanisms contribute to fatigue in cyclists. You are not as much of a headcase as you think…

Happy Training

Kremenic IJ, Glace BW, Ben-Avi SS, Nicholas SJ, McHugh MP. Central fatigue after cycling evaluated using peripheral magnetic stimulation. Med Sci Sports Exerc. 2009 Jul;41(7):1461-6.