TY - JOUR
T1 - Menstrual cycle and oral contraceptives' effects on growth hormone response to sprinting
AU - Sunderland, C
AU - Tunaley, V
AU - Horner, Fleur
AU - Harmer, D
AU - Stokes, Keith A
PY - 2011
Y1 - 2011
N2 - The present study examined the impact of the menstrual cycle and oral contraceptive (OC) use on the growth hormone response to nonmotorized treadmill sprinting. Nine monophasic OC users (21.5 +/- 4.7 years old), and 8 normally menstruating women (NM; 21.4 +/- 2.9 years old) participated in the study. Each participant completed 2 main trials, each consisting of an all-out 30-s treadmill sprint. The NM group performed one trial in the midfollicular phase (NM follicular) and one in the midluteal phase (NM luteal); the OC group's trials occurred one week into the start of the pill-taking cycle and once during the week in which pills were not taken. Venous blood samples were analyzed for growth hormone, pH, lactate, glucose, and progesterone concentrations. Peak and mean power output did not differ between the groups or with menstrual phase, or between the OC-free and OC trials. Integrated growth hormone was greater in the OC group than in the NM group (p = 0.04) with no phase difference (p = 0.80, mean (SD); NM follicular: 421 (335) and NM luteal: 345 (304) vs. OC free: 737 (471) and OC: 758 (389) mu g.L-1.90 min(-1)). Blood lactate was higher in the OC group than in the NM group (p = 0.007) and, conversely, pH was lower in the OC group (p = 0.01). These results demonstrate that OC users who take high-androgenicity pills have a higher growth hormone response to sprint running than do normally menstruating women.
AB - The present study examined the impact of the menstrual cycle and oral contraceptive (OC) use on the growth hormone response to nonmotorized treadmill sprinting. Nine monophasic OC users (21.5 +/- 4.7 years old), and 8 normally menstruating women (NM; 21.4 +/- 2.9 years old) participated in the study. Each participant completed 2 main trials, each consisting of an all-out 30-s treadmill sprint. The NM group performed one trial in the midfollicular phase (NM follicular) and one in the midluteal phase (NM luteal); the OC group's trials occurred one week into the start of the pill-taking cycle and once during the week in which pills were not taken. Venous blood samples were analyzed for growth hormone, pH, lactate, glucose, and progesterone concentrations. Peak and mean power output did not differ between the groups or with menstrual phase, or between the OC-free and OC trials. Integrated growth hormone was greater in the OC group than in the NM group (p = 0.04) with no phase difference (p = 0.80, mean (SD); NM follicular: 421 (335) and NM luteal: 345 (304) vs. OC free: 737 (471) and OC: 758 (389) mu g.L-1.90 min(-1)). Blood lactate was higher in the OC group than in the NM group (p = 0.007) and, conversely, pH was lower in the OC group (p = 0.01). These results demonstrate that OC users who take high-androgenicity pills have a higher growth hormone response to sprint running than do normally menstruating women.
UR - http://www.scopus.com/inward/record.url?scp=80051972831&partnerID=8YFLogxK
UR - http://dx.doi.org/10.1139/h11-039
U2 - 10.1139/h11-039
DO - 10.1139/h11-039
M3 - Article
SN - 1715-5312
VL - 36
SP - 495
EP - 502
JO - Applied Physiology Nutrition and Metabolism
JF - Applied Physiology Nutrition and Metabolism
IS - 4
ER -