Context: The effects of caffeine on muscle cramp threshold frequency were investigated. Objective: To determine the effect of caffeine on muscle cramp threshold frequency. Design: Randomized Trial. Experimental Design Setting: Institutional Research Laboratory. Participants: 11 males, 6 females. Intervention: Each subject ingested different caffeine doses over three testing days. Main Outcome Measures: Muscle cramp threshold frequency, hemoglobin, hematocrit, plasma sodium concentration, plasma potassium concentration, plasma chloride concentration, and osmolality were recorded. Results: There was a significant difference between baseline and post ingestion threshold frequency as well as significant differences between 0 mg to 500 mg and 250 mg to 500 mg. Hemoglobin, plasma potassium concentration, and osmolality were significantly different from pre to post ingestion. Conclusions: There was a significant difference from pre to post muscle cramp threshold frequency. Hemoglobin, plasma potassium concentration, and osmolality were significantly different pre to post ingestion. The significance of these findings requires further study.