EFFECTS OF THE MENSTRUAL-CYCLE PHASE ON THE BLOOD LACTATE RESPONSES TO EXERCISE

The effects of menstrual cycle phase on the blood lactate response to exercise were examined in eumenorrheic women (n=9). Exercise tests wer e performed at the mid-follicular and mid-luteal points in the menstru al cycle (confirmed by basal body temperature records and hormone leve ls). Blood lactates were measured at rest and during the recovery from exercise. Resting lactates were not different between the exercise te sts; however, recovery lactates were significantly (p<0.05) lower in t he luteal compared to the follicular phase. The mechanism for these di fferences is unclear, but may be related to an estrogen mediated incre ased lipid metabolism inducing a concurrent reduction in carbohydrate metabolism. The present findings question the use of blood lactate mon itoring as a suitable technique to measure exercise intensity in eumen orrheic women.