Submitted on September 10, 2004
Accepted on December 9, 2004
Heat Acclimation and Physical Training Adaptations of Young Women Using Different Contraceptive Hormones
Lawrence E. Armstrong1*, Carl M. Maresh1, NiCole R. Keith2, Tabatha A. Elliott2, Jaci L. VanHeest2, Timothy P. Scheett2, James Stoppani2, Daniel A. Judelson2, and Mary Jane De Souza3
1 Human Performance Laboratory, Department of Kinesiology, University of Connecticut, Storrs, CT, USA; Department of Physiology and Neurobiology, University of Connecticut, Storrs, CT, USA
2 Human Performance Laboratory, Department of Kinesiology, University of Connecticut, Storrs, CT, USA
3 Human Performance Laboratory, Department of Kinesiology, University of Connecticut, Storrs, CT, USA; Women's Exercise and Bone Health Laboratory, Department of Exercise Science, University of Toronto, Toronto, ON, Canada
* To whom correspondence should be addressed. E-mail: lawrence.armstrong{at}uconn.edu.
Although endogenous and exogenous steroid hormones affect numerous physiologic
processes, the interactions of reproductive hormones, chronic exercise training and heat
acclimation are unknown. This investigation evaluated the responses and adaptations of 36
inactive females (mean ± SD; age, 21 ± 3y) as they undertook a 7-8 wk program (HAPT) of
indoor heat acclimation (90 min.d-1, 3 d.wk-1) and outdoor physical training (3 d.wk-1) while
using either an oral estradiol-progestin contraceptive (ORAL, n=15), a contraceptive
injection of depot medroxyprogesterone acetate (DEPO, n=7), or no contraceptive (EU-OV,
n=14; control). Standardized physical fitness and exercise-heat tolerance tests (EHT;
36.5°C, 37%rh), administered before and after HAPT, demonstrated that the three subject
groups successfully (P<0.05) acclimated to heat (i.e., rectal temperature, heart rate) and
improved muscular endurance (i.e., situps, pushups, 4.6-km run time), and body
composition characteristics. The stress of HAPT did not disrupt the menstrual cycle
length/phase characteristics, ovulation, or plasma hormone concentrations of EU-OV. No
between-group differences (P>0.05) existed for rectal and skin temperatures, metabolic,
cardiorespiratory, muscular endurance, or body composition variables. A significant
difference post-HAPT in the onset temperature of local sweating, ORAL (37.2 ± 0.4°C)
versus DEPO (37.7 ± 0.2°C), suggested that steroid hormones influenced this adaptation.
In summary, virtually all adaptations of ORAL and DEPO were similar to EU-OV, suggesting
that exogenous reproductive hormones neither enhanced nor impaired the ability of women
to complete 7- 8 wk of strenuous physical training and heat acclimation.
