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December 18, 2003
First-of-its kind study concludes circulating endogenous hormone profile is more dependent on exercise mode or intensity than exercise volume as measured by caloric expenditure in men
DECEMBER 3, 2003 (Bethesda, MD) -- There are a number of reasons why, in men, the manipulation of anabolic hormones (such as testosterone) and the anabolic/catabolic hormone ratio (e.g., testosterone/cortisol) might be beneficial. From the perspective of an athlete, an increase in anabolic-androgenic hormones can improve performance by decreasing body fat and increasing lean body mass and muscular strength. Among older men, it may help to replace the decline in testosterone, which can negatively affect body composition and physical function.
Studies have shown that endurance-trained men tend to have lower levels of testosterone compared to their sedentary counterparts and that resistance-trained men have higher basal testosterone levels. Studies have also found that both endurance- and resistance-trained males had lower testosterone levels than sedentary control subjects. Thus, while it is known that training status can influence the hormone response to exercise, it is not clear whether the mode of training can affect the hormone response to different modes of exercise. Such information could be useful in designing training regimes that will result in the most favorable ratio of anabolic and catabolic hormones.
A first-of-its-kind study attempts to determine the acute steroid hormone response to endurance and resistance exercise bouts of equitable volume in subjects with differing training status. The newly released findings conclude that the circulating endogenous hormone profile is more dependent on exercise mode or intensity than on exercise volume as measured by caloric expenditure. The study also provides evidence that hormone levels and exercise-induced hormone changes are different in subjects of different training status.
A New Study
The authors of the study, entitled, “Effect of Training Status and Exercise Mode on Endogenous Steroid Hormones in Males,” are Mark S. Tremblay, Jennifer L. Copeland, and Walter Van Helder, all of the College of Kinesiology, University of Saskatchewan, Saskatoon, SK, Canada. Their findings appear in the “Articles in Press” section of the Journal of Applied Physiology. The Journal of Applied Physiology is one of 14 scientific journals published each month by the American Physiological Society (APS).
Summary of Methodology
Twenty-two healthy males were recruited who were resistance-trained (RES, N=7), endurance-trained (END, N=8) or sedentary (SED, N=7). Each screened volunteer participated in four late afternoon sessions. This time was chosen because it best represented the typical time period during which the subjects trained and because variation of testosterone is minimized during this period.
During session one, baseline anthropometric and fitness measurements were obtained. During session two subjects rested quietly. A resting blood sample was drawn at 0.5 hours and subsequent blood samples were drawn each hour for the subsequent four hours. Plasma was analyzed for luteinizing hormone (LH), dehydroepiandrosterone sulfate (DHEAS), cortisol, and free and total testosterone. Endurance and resistance exercise bouts were completed during sessions three and four. These exercise sessions were matched according to caloric expenditure (calculated from expired gases). Each testing session was separated by at least one week.
Height, body mass, and skinfold thickness were taken, and strength measurements were performed. Maximal aerobic power was determined using a progressive, incremental treadmill protocol. Minute ventilation (VE), oxygen consumption (VO2), carbon dioxide production (VCO2), and respiratory exchange ratio (RER) were monitored.
All data were presented as means ± standard deviation, and statistical significance was set at p<0.05. Total testosterone/cortisol, free testosterone/cortisol and DHEAS/cortisol ratios were calculated and compared in the same manner as individual hormones.
Results
Highlights of the findings include:
· Subject Characteristics: The resistance-trained subjects (RES) were significantly heavier and stronger than the endurance-trained (END) or sedentary (SED) subjects. The END subjects had significantly greater maximal aerobic power. Body mass did not change prior to or during the study.
· Exercise Sessions: Cardiorespiratory data were collected every minute during the exercise sessions, and the individual means for each session were averaged by group. The 40-minute run resulted in greater VO2 and VCO2 and lower RER than the resistance exercise. END subjects had significantly higher relative VO2 values and significantly lower RER during the run compared to RES and SED subjects. RES subjects had a higher mean heart rate during resistance exercise compared to END subjects.
· Luteinizing Hormone: When subjects were taken as a whole, there was a significant main effect for the resistance exercise session, resulting in greater LH concentrations than for the rest or the run. In the RES subjects, there was a significant increase in LH during recovery from the run.
· DHEAS: When the subjects were analyzed together, the resistance exercise session resulted in significantly greater DHEAS concentrations compared with rest or the run. The levels of DHEAS during the resistance exercise session were significantly greater in RES subjects compared to SED or END. During the run session, END subjects showed greater DHEAS concentrations than RES subjects. DHEAS levels remained elevated in recovery after resistance exercise in RES subjects.
· Cortisol: The concentrations of cortisol tended to decline across time, particularly in the resting session, consistent with the typical diurnal pattern of cortisol. However, when all subjects were analyzed together, cortisol concentrations were significantly higher in the resistance exercise session compared to the rest or the run, and was higher in the run session compared to rest. There were no significant group differences in the cortisol concentrations, although there was a significant group by session interaction that indicated a dampened response to resistance exercise in endurance-trained subjects.
· Total Testosterone: There was an increase in total testosterone after exercise, particularly after resistance exercise. There was a significant session by time interaction due to the pronounced decline in total testosterone during recovery from resistance exercise. Area under the curve results indicated that the SED subjects had significantly greater total testosterone concentrations compared to END or RES subjects.
· Free Testosterone: The changes in free testosterone across sessions closely matched the changes in total testosterone. When all subjects were analyzed together, free testosterone was significantly greater during the resting session than during the run or resistance exercise session. As seen with total testosterone, there was a significant decline in free testosterone during recovery from resistance exercise, despite an initial increase after exercise. Testosterone increased back to baseline levels by time 4 following resistance exercise.
· Ratios: The total and free testosterone/cortisol ratios were significantly higher during the resting session and the run compared to the resistance exercise. The DHEAS/cortisol ratio was significantly greater during rest than exercise session and was also greater during the run compared to the resistance session. There were no significant differences between groups for any of the ratios.
· Plasma Volume Changes. Hematocrit levels were significantly greater during the resistance exercise session than the resting session and were higher at time 1 than at time 0, 2, 3 or 4 (p<0.05) in the resistance exercise session. All groups showed similar changes in hematocrit following exercise, but there was a significant group by session interaction indicating that resistance-trained subjects had greater increases in hematocrit following resistance exercise.
Conclusions
Sedentary, resistance-trained, and endurance-trained subjects were used in this study to identify differences in testosterone, LH, DHEAS, and cortisol, as well as the ratios of testosterone and DHEAS to cortisol. Based on the results of this study, it appears that the circulating endogenous hormone profile is more dependent on exercise mode or intensity than on exercise volume as measured by caloric expenditure. The relatively catabolic environment observed during the resistance session may indicate an intensity-dependent rather than mode-dependent response. The study also provides evidence that hormone levels and exercise-induced hormone changes are different in subjects of different training status.
Source: Journal of Applied Physiology, “Articles in Press” section. The Journal is one of 14 scientific journals published each month by the American Physiological Society (APS).
The American Physiological Society (APS) was founded in 1887 to foster basic and applied science, much of it relating to human health. The Bethesda, MD-based Society has more than 10,000 members and publishes 3,800 articles in its 14 peer-reviewed journals every year.
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