Water and Fatigue
by G.C. Pitts
from "Factors Affecting Work Output in Hot Environments", American
Journal of Physiology
In the early 1940s a group of researchers at Harvard tested the effect
of dehydration on exercise fatigue in a group of conditioned athletes.
The athletes walked on a treadmill at a constant speed in a hot environment
under three conditions: no water, water on demand, and water replacement
commensurate with water loss. When the athletes were given no water,
their body temperatures reached 102 degrees in 3.5 hours, and they were
exhausted. When the athletes could drink as much as they wanted, they
lasted 6 hours before their temperatures reached 102 and they became
exhausted. But when the athletes drank enough water to replace all they
were losing as they were exercising, the researchers ended the experiment
at seven hours because the athletes felt they could continue indefinitely!
Their temperatures remained at a steady 99 degrees.
(G.C. Pitts et al, "Factors
Affecting Work Output in Hot Environments" American Journal of Physiology,
1944, 142: 254)