Heat Regulation in Bicycling and Human Powered Vehicles

 

Elevations in Core and Muscle Temperature Impairs Repeated Sprint Performance

Acta Physiol Scand. 2005 Feb;183(2):181-90.

Hyperthermia impaired power output during sprints. Researchers found no evidence excess heat caused accumulation of muscle fatigue agents and theorized impaired performance resulted from affect of increased core temperature on central nervous system.

 

The Cardiovascular Challenge of Exercising in the Heat

The Journal of Physiology, Jan 1, 2008  586, 45-53

In short, high-intensity exercises such as sprints, physiological adjustments meet muscular needs for energy. As exercise continues, need for blood flow in the skin competes for muscular blood flow requirements. Continued competition between skin and muscle for blood flow impairs central nervous system cooling. Increased brain temperatures make it difficult to continue exercise.

 

Heat Stress and Baroreflex Regulation of Blood Pressure

Med Sci Sports Exerc. Dec 2008; 40(12): 2063
Heat stress does not impair baroreflex control of heart rate. Muscle sympathetic nerve activity is either unchanged or elevated during heat stress. Postsynaptic vasoconstrictor responses in the skin are weakened by heat stress. Similar to the effects of exercise, heat stress drives baroreflexes toward prevailing heart rate, muscle sympathetic nerve activity and blood pressure.

Brain Temperature and Limits on Transcranial Cooling in Humans

Eur J Appl Physiol Occup Physiol. 1998 Sep;78(4):353-9.
Brain temperature is a product of arterial temperature and systemic thermoregulation unrelated to scalp temperature. Surface cooling of the head may not directly protect against cranial heat damage, but scalp temperatures above core temperatures may contribute to environmental heat injury.

The effects of passive heating and head-cooling on perception of exercise in the heat

European Journal of Applied Physiology Sept 2008, Volume 104, Issue 2, pp 281-288

Increased core temperatures increase perception of exercise in heat

Cooling the neck region during exercise in the heat

J Athl Train. 2011 Jan-Feb;46(1):61-8. doi: 10.4085/1062-6050-46.1.61

Cooling the neck can reduce perceptions of heat stress during exercise.

 

The Effect of Two Cycling Helmets on Thermoregulation and Heat Perceptions During Exercise...

D. Jason Gillis Dept. of Sport and Exercise Science Univ. of Portsmouth, England, UK.
Well ventilated helmet did not make a significant difference in perceptions of cooling.