Title

Oral contraceptive use, physical conditioning, and heat exposure in college women

Date of Completion

January 1999

Keywords

Health Sciences, Obstetrics and Gynecology|Biology, Animal Physiology|Women's Studies|Health Sciences, Recreation

Degree

Ph.D.

Abstract

The present study examined the cardiovascular and thermoregulatory responses of college women who ingested oral contraceptives (ORAL, n = 10) and those who were eumenorrheic and ovulatory (EU-OV, n = 9). Subjects performed maximum volume of oxygen uptake (VO2max) tests and exercise heat tolerance (EHT) tests during the early follicular phase, before and after an eight-week exercise training-heat acclimation (ET-HA) program. Prior to the EHT tests subjects were dehydrated to –2.69 ± 0.58% (ORAL, EHT test one), –2.94 ± 0.50% (EU-OV, EHT test one), –2.88 ± 0.57% (ORAL, EHT test two), and –2.94 ± 0.46 (EU-OV, EHT test two) via supervised exercise and water restriction. Each week, the ETHA program involved three days of exercise-heat exposure in an environmental chamber and three days of outdoor group running, sit-ups, and push-ups. Results from this research showed that the ORAL group had a significantly higher mean VO 2max value (p < .05) following ET-HA when compared to the ORAL mean pre-training value. When ORAL and EU-OV VO2max values were compared, there were no between-group differences in VO2max, maximum heart rate (HRmax), total exercise time, or rating of perceived exertion (RPE) before or after ET-HA. During the EHT test there were no between-group differences in fluid responses (i.e. dehydration percent weight loss, EHT test arrival weight, urine specific gravity, and EHT test body sweat loss) HR, rectal temperature (Tre), mean weight skin temperature (Tsk), thermal sensation (TS), or RPE before or after ET-HA. The ORAL group exhibited between-test differences (p < .01) in HR at the time period corresponding to the end of exercise during EHT test 1 (END 1).^ Between-test differences in Tsk were seen in the EU-OV group (p < .05) five minutes following the end of the EHT tests. Between-test differences in TS were seen in the ORAL group (p < .05) at the 30 minute EHT test stage. The ORAL group showed between-test differences in RPE (p < .05) at the END 1 EHT test stage. Results from this research suggested that ORAL and EU-OV groups were not different when cardiovascular fitness and heat tolerance status were examined before and after ET-HA. In addition, these groups responded similarly to the processes of ET-HA during menstruation. ^