Intermittent high-intensity sports encompass those sports requiring athletes to perform exercise, predominantly of anaerobic nature, interspersed with less demanding, active recovery and/or variable rest periods. Far less is understood about how hypohydration and dehydration impact strength, power, and subsequent performance in intermittent high-intensity sports. High-quality literature reviews of older and newer studies report dehydration or hypohydration up to 7% body mass loss inconsistently affects strength and power, both in frequency and magnitude of effect. While single-effort measures of strength and power provide some insight into the dehydration-performance interaction, intermittent high-intensity sports frequently demand repeated strength and power generation. Dehydration clearly alters aerobic metabolism, potentially creating a butterfly effect that diminishes strength and power performance during subsequent bouts. The effects of dehydration on cognitive performance appear transient, lasting only hours or minutes following dehydration in the heat and with exercise so long as fluid is adequately replenished.