Studies have found an array of endocrine disturbances related to energy deprivation in women with functional hypothalamic amenorrhea.
Purpose: We examined the catecholamine response to exercise in five eumenorrheic (EU) and five amenorrheic (AM) athletes, matched by age (mean ± SEM: EU = 29.8 ± 2.5 yr and AM = 31.0 ± 4.3 yr) and running volume (EU = 56.4 ± 8.1 km·wk−1 and AM = 61.5 ± 6.4 km·wk−1).
Methods: Subjects performed a maximal treadmill test followed by a 30-min recovery and then a submaximal running test, consisting of 4-min stages at 60%, 70%, and 80% and 15 min at 85% of peak oxygen consumption (V˙O2peak). Blood was drawn after each stage to measure glucose, lactate, epinephrine, norepinephrine, and cortisol concentrations. HR, blood pressure, and rate of perceived exertion were also measured at each stage.
Results: There were no differences between groups in body composition or V˙O2peak (EU = 57.3 ± 2.3 mL·kg−1·min−1 and AM = 54.1 ± 1.2 mL·kg−1·min−1). Resting HR and mean arterial pressure were significantly (P ≤ 0.05) lower in AM. Norepinephrine was lower in AM at 70%, 80%, 85%, and 100% of V˙O2peak (EU = 7784.5 ± 582.9 pg·mL−1 and AM = 3626.1 ± 271.4 pg·mL−1 at V˙O2peak). Epinephrine (EU = 1470.3 ± 275.1 pg·mL−1 and AM = 416.9 ± 67.5 pg·mL−1) and blood lactate (EU = 10.1 ± 1.2 mmol·L−1 and AM = 6.7 ± 0.9 mmol·L−1) were lower at V˙O2peak in AM.
Conclusions: Our results demonstrate a reduced adrenergic response to intense exercise in AM athletes as indicated by reduced blood lactate and catecholamine concentrations. A suppressed catecholamine response could decrease performance by reducing the sympathetic drive essential for the cardiovascular and metabolic adjustments needed to maintain high intensities of exercise.