PURPOSE:: Dehydration is hypothesized to cause exercise-associated muscle cramps (EAMC). The theory states that dehydration contracts the interstitial space thereby increasing the pressure on nerve terminals and cramps ensue. Research supporting this theory is often observational and fatigue is rarely controlled. Inducing cramps with electrical stimulation minimizes many of the confounding factors associated with exercise-induced cramps (eg, fatigue, metabolites). Thus, our goal was to minimize fatigue and determine if hypohydration decreases the electrical stimuli required to elicit cramping (termed "threshold frequency"). METHODS:: Ten males cycled for 30 min bouts with their nondominant leg at 41 degrees C and 15% relative humidity until they lost ~3% of their body mass (~2 h). Dominant leg flexor hallucis brevis muscle cramps were induced pre and posthypohydration and threshold frequency was recorded. Plasma osmolality (OSMp) characterized hydration status. Total sweat electrolytes (Na, K, Mg, and Ca) lost during exercise was calculated. Subjects repeated the protocol 1 week later. RESULTS:: Subjects were hypohydrated postexercise (preexercise OSMp= 282.5 +/- 0.7 mOsm*kg H2O, postexercise OSMp=295.1+/-1.1 mOsm*kg H2O, P<0.001). Subjects lost 3.0+/-0.1% of their body mass, 144.9+/-9.8 mmol of Na, 11.2+/-0.4 mmol of K, 3.3+/-0.3 mmol of Mg, and 3.1+/-0.1 mmol of Ca. Mild hypohydration with minimal neuromuscular fatigue did not affect threshold frequency (euhydrated=23.7+/-1.5 Hz, hypohydrated=21.3+/-1.4 Hz; F1,9=2.81, P=0.12).