Objective: To assess whether Ramadan intermittent fasting (RIF) affects 5000-m running performance and physiological parameters classically associated with middle-distance performance. Design: Two experimental groups (Ramadan fasting, n = 9, vs control, n = 9) participated in 2 experimental sessions, one before RIF and the other at the last week of fasting. Setting: For each session, subjects completed 4 tests in the same order: a maximal running test, a maximal voluntary contraction (MVC) of knee extensor, 2 rectangular submaximal exercises on treadmill for 6 minutes at an intensity corresponding to the first ventilatory threshold (VT1), and a running performance test (5000 m). PARTICIPANTS:: Eighteen, well-trained, middle-distance runners. Main Outcome Measures: Maximal oxygen consumption, MVC, running performance, running efficiency, submaximal &OV0312;O2 kinetics parameters (&OV0312;O2, &OV0312;O2b, time constant τ, and amplitude A1) and anthropometric parameters were recorded or calculated. Results: At the end of Ramadan fasting, a decrease in MVC was observed (-3.2%; P < 0.00001; η 2, 0.80), associated with an increase in the time constant of oxygen kinetics (+51%; P < 0.00007; η, 0.72) and a decrease in performance (-5%; P < 0.0007; η, 0.51). No effect was observed on running efficiency or maximal aerobic power. Conclusions: These results suggest that Ramadan changes in muscular performance and oxygen kinetics could affect performance during middle-distance events and need to be considered to choose training protocols during RIF. © 2011 Lippincott Williams & Wilkins.
