Testosterone, Cortisol, and Creatine Kinase Levels in Male Distance Runners During Reduced Training J. A. Houmard, D. L. Costill, J. B. Mitchell, S. H. Park, W. J. Fink, andJ. M. Bums Human Performance Laboratory, Ball State University, Muncie, IN 47306
Introduction Abstract
Endurance training has been observed to
During Reduced Training. mt J Sports med, Vol 11, No!, pp 41—45, 1990.
Accepted after revision: May 1, 1989 The purpose of this study was to examine if re-
duced training would reestablish normal testosterone, cortisol, and creatine kinase (CK) levels in male distance runners. Ten male runners (mean SE) age 32.0 2.6 yrs, bodyfat9.6 l.0%,VO2max 61.8 1.1 mi/kg/mm) were
monitored during 4 weeks of normal training (baseline training, BT) and 3 weeks of reduced training (RI). During
BT running distance averaged 81
5 km/week, 6
days/week. During RT the runners reduced weekly training volume by 70% of BT to 24 2 km/week and training frequency to 5 days/week. Weekly resting blood samples were obtained between 0600—0900 hrs after an overnight fast. During BT resting total testosterone levels averaged
5.10 0.21 ng/ml, which is within the low ranges previously reported in male distance runners. Testosterone levels were not affected by RT(avg of 5.38 0.31 ng/ml).
are apparently adaptative responses to the physiological and psychological stresses associated with training (14, 16, 19, 21, 23, 32). Total CK has been used as a marker of muscle tissue damage (5—7, 25, 27, 28). The elevations in resting total CK may reflect increased damage with repeated days of training (12,17,19,25—29).
Reduced training has been observed to improve performance (9) due to a reduction of the stresses associated with intense training. A reduction in training stress may also return testosterone, cortisol, and CK levels to normal in training male runners. With testosterone this could be of im-
portance since oligospermia has been observed in male endurance runners with extremely low testosterone levels (1). However, few studies have examined the sensitivity of testost-
erone, cortisol (29), and CK (26) to a training reduction. Therefore, the purpose of this study was to determine if a 3
week reduction in weekly training volume (70%) and frequency (17 %) would reestablish normal testosterone, cortisol, and CKlevels in male distance runners.
Methods
Cortisol levels were in the high range of normal during BT 1.18 ug/dl) and were not altered with RI (avg of (23.61 23.14 1.56 ug/dl). Creatine kinase was elevated (168 15 U/L) during BT and was significantly reduced
(P < 0.001) at weeks 1—3 of RT (avg of 99 9 U/L). These results suggest that normally training male runners have low
resting total testosterone levels and cortisol levels in the high-normal range. Resting testosterone and cortisol were not responsive to the training reduction. Creatine kinase appears to be sensitive to relative changes in training.
Experimental Design Ten well-trained male distance runners volun-
teered to participate after being informed of the risks and benefits involved. The runners selected were serious competitive athletes, although not at the elite level. Subjects had maintained endurance training for at least 2 yrs. Characteristics of the subjects are presented in Table 1.
After initial testing for VO2max, the subjects were monitored while training at their normal weekly running
Key words
Testosterone, cortisol, creatine kinase, reduced training, male distance runners
Table I Subject characteristics Characteristic
Value
Age (yrs) Height (cm) Weight (kg)
32.0
2.6
175 62.2
2.0
Body fat (%)
VO2max (mi/kg/mm)
Int.J. Sports Med. 11(1990)41-45
GeorgmiemeVerlagStuttgart NewYork
Values are mean SE, N = 10; VO2max, maximal oxygen consumption.
9.6 61.81
1.4 1.0 1.08
Downloaded by: University of British Columbia. Copyrighted material.
J. A. Houmard, D. L. Costill, J. B. Mitchell, S. H. Park, W. J. Fink, andJ. M. Bums, Testosterone, Cortiso!, and Creatine Kinase Levels in Male Distance Runners
decrease resting total testosterone (1, 15, 32), and increase cortisol (2, 19, 23, 29) and total creatine kinase (CK) (12, 19, 25— 29) levels in males. These testosterone and cortisol alterations
42 mt. J. Sports Med. 11(1990)
J. A. Houmard, D. L. Costill, J. B. Mitchell, S. H. Park, W. J. Fink, and J.M. Burns
distance for 4 weeks. Based upon descriptions of their normal training, each subject was provided with a schedule detailing pace and distance. This period is described as baseline training
(BT). During BT subjects ran (mean SE) 81 5 km/week,
6 days/week. Approximately 60 km/week were run at normal training pace ( — 75% O2max, as based on VO2max results) with the remainder (21 km/week) at — 95% VO2max in the form of intervals and weekly 5km races.
Body weights were recorded weekly, and body fat was estimated using skinfolds (3) on BT weeks 1 and 4, and RT week 3. To insure that the conditioning level of the subjects did not change, VO2max was determined on BT weeks 2 and 4,
and RT week 3 with an incremental treadmill test. Expired gases were analyzed continuously for 02 (Applied Electrochemistry S-3A 02 Analyzer), C02 (Beckman, LB-2 Medical Gas Analyzer), and total volume (Parkinson/Cowan gas meter).
training volume was reduced by 70% of BT to 24 2
km/week and training frequency by 17% to 5 days/week. The subjects ran 17 km/week at normal pace (— 75% VO2max), with the remaining 7 km/week as intervals and weekly 5 km races ( — 95 % VOmax). The percentage of weekly distance performed as intervals and 5 km races was approximately the same during RT(29 %) and BT(26 %).
Statistical analysis: All measures are expressed
as mean SE. Repeated measures analysis of variance (ANOVA) was used to identify differences between the dependant variables. Specific mean differences were identified using a Newman-Keuls post-hoc test. The level of significance was P < 0.05. There were no significant differences between any measures during the 4 weeks of BT; results were, thus, averaged and compared with each week of RT. Results
To insure adherance to RT, subjects under-
Resting Testosterone, Cortisol, Creatine Kinase, and Plasma Volume
stood that monetary reward for participation in the study would be witheld if there was any deviation. The subjects were
reminded to maintain BT and RT during testing and by telephone calls. The runners were also required to periodically report to the laboratory before and after training. We felt that these safeguards insured that all subjects followed the BT and RT schedules.
Testing Procedures
Resting total testosterone, cortisol, and the tes-
tosterone/cortisol ratio were not altered with RT (Table 2). Total CK levels decreased significantly (P < 0.001) during all 3 weeks of RT as compared to BT (Fig. 1). Plasma volume decreased slightly, but significantly, as compared to BT, (P < 0.01) by 5.6 1.3 % at RT week 3. Since hemoconcentration did not confound the data (Table 2, Fig. I), the results presented are not corrected for hemoconcentration at RT week 3.
Weekly Testing: Each subject was tested at the same time (0600—0900 hrs) on the same day of each week to ac-
count for diurnal variation in hormone responses (14,21). The subjects reported to the laboratory 0.5—1 hr after waking and an overnight fast. Subjects had not exercised in the previous 12 hrs. After the subjects had remained seated for 20 mm, a blood sample (— 10 ml) was drawn from an antecubital vein. No anticipatory rise in cortisol occurs in this setting, as demonstrated in other studies (18, 30). A portion of the blood sample was im-
mediately analyzed for hemoglobin (cyanmethemoglobin) and hematrocrit (microcentrifugation) for the determination of percent changes in plasma volume (PV) (11). The remainder was placed in a sterile collection tube and allowed to clot. The blood was then centrifuged, separated, and stored at —80 °C
Anthropometic Measures and Maximal Oxygen Consumption There were no significant differences in body weight (kg) during RT (mean for 3 weeks, 62.5 2.1) versus BT (62.2 2.0). Percent body fat (9.6 1.1 for BT versus 9.6 0.9 for RT week 3) was not affected by RT. Aerobic capacity, as indicated by VO2max, was not altered with RT 1.1 versus 60.9 1.2 ml/kg/min for BT and RT week (61.8 3, respectively). Body fat and aerobic capacity, therefore, did not influence the blood measures obtained in this study. Discussion
for subsequent analysis. Serum cortisol was determined by solid-phase radioimmunoassay (RIA) using a commercially available test kit (NML, Organon Teknika Corp. Irving, TX), which had minimal cross-reactivity (< 10%) with cortisol analogs. Total testosterone was also determined by using a solid-phase RIA kit (Radioassay Systems Labs, INC:, Carson, CA), with minimal cross-reactivity (
Introduction Abstract
Endurance training has been observed to
During Reduced Training. mt J Sports med, Vol 11, No!, pp 41—45, 1990.
Accepted after revision: May 1, 1989 The purpose of this study was to examine if re-
duced training would reestablish normal testosterone, cortisol, and creatine kinase (CK) levels in male distance runners. Ten male runners (mean SE) age 32.0 2.6 yrs, bodyfat9.6 l.0%,VO2max 61.8 1.1 mi/kg/mm) were
monitored during 4 weeks of normal training (baseline training, BT) and 3 weeks of reduced training (RI). During
BT running distance averaged 81
5 km/week, 6
days/week. During RT the runners reduced weekly training volume by 70% of BT to 24 2 km/week and training frequency to 5 days/week. Weekly resting blood samples were obtained between 0600—0900 hrs after an overnight fast. During BT resting total testosterone levels averaged
5.10 0.21 ng/ml, which is within the low ranges previously reported in male distance runners. Testosterone levels were not affected by RT(avg of 5.38 0.31 ng/ml).
are apparently adaptative responses to the physiological and psychological stresses associated with training (14, 16, 19, 21, 23, 32). Total CK has been used as a marker of muscle tissue damage (5—7, 25, 27, 28). The elevations in resting total CK may reflect increased damage with repeated days of training (12,17,19,25—29).
Reduced training has been observed to improve performance (9) due to a reduction of the stresses associated with intense training. A reduction in training stress may also return testosterone, cortisol, and CK levels to normal in training male runners. With testosterone this could be of im-
portance since oligospermia has been observed in male endurance runners with extremely low testosterone levels (1). However, few studies have examined the sensitivity of testost-
erone, cortisol (29), and CK (26) to a training reduction. Therefore, the purpose of this study was to determine if a 3
week reduction in weekly training volume (70%) and frequency (17 %) would reestablish normal testosterone, cortisol, and CKlevels in male distance runners.
Methods
Cortisol levels were in the high range of normal during BT 1.18 ug/dl) and were not altered with RI (avg of (23.61 23.14 1.56 ug/dl). Creatine kinase was elevated (168 15 U/L) during BT and was significantly reduced
(P < 0.001) at weeks 1—3 of RT (avg of 99 9 U/L). These results suggest that normally training male runners have low
resting total testosterone levels and cortisol levels in the high-normal range. Resting testosterone and cortisol were not responsive to the training reduction. Creatine kinase appears to be sensitive to relative changes in training.
Experimental Design Ten well-trained male distance runners volun-
teered to participate after being informed of the risks and benefits involved. The runners selected were serious competitive athletes, although not at the elite level. Subjects had maintained endurance training for at least 2 yrs. Characteristics of the subjects are presented in Table 1.
After initial testing for VO2max, the subjects were monitored while training at their normal weekly running
Key words
Testosterone, cortisol, creatine kinase, reduced training, male distance runners
Table I Subject characteristics Characteristic
Value
Age (yrs) Height (cm) Weight (kg)
32.0
2.6
175 62.2
2.0
Body fat (%)
VO2max (mi/kg/mm)
Int.J. Sports Med. 11(1990)41-45
GeorgmiemeVerlagStuttgart NewYork
Values are mean SE, N = 10; VO2max, maximal oxygen consumption.
9.6 61.81
1.4 1.0 1.08
Downloaded by: University of British Columbia. Copyrighted material.
J. A. Houmard, D. L. Costill, J. B. Mitchell, S. H. Park, W. J. Fink, andJ. M. Bums, Testosterone, Cortiso!, and Creatine Kinase Levels in Male Distance Runners
decrease resting total testosterone (1, 15, 32), and increase cortisol (2, 19, 23, 29) and total creatine kinase (CK) (12, 19, 25— 29) levels in males. These testosterone and cortisol alterations
42 mt. J. Sports Med. 11(1990)
J. A. Houmard, D. L. Costill, J. B. Mitchell, S. H. Park, W. J. Fink, and J.M. Burns
distance for 4 weeks. Based upon descriptions of their normal training, each subject was provided with a schedule detailing pace and distance. This period is described as baseline training
(BT). During BT subjects ran (mean SE) 81 5 km/week,
6 days/week. Approximately 60 km/week were run at normal training pace ( — 75% O2max, as based on VO2max results) with the remainder (21 km/week) at — 95% VO2max in the form of intervals and weekly 5km races.
Body weights were recorded weekly, and body fat was estimated using skinfolds (3) on BT weeks 1 and 4, and RT week 3. To insure that the conditioning level of the subjects did not change, VO2max was determined on BT weeks 2 and 4,
and RT week 3 with an incremental treadmill test. Expired gases were analyzed continuously for 02 (Applied Electrochemistry S-3A 02 Analyzer), C02 (Beckman, LB-2 Medical Gas Analyzer), and total volume (Parkinson/Cowan gas meter).
training volume was reduced by 70% of BT to 24 2
km/week and training frequency by 17% to 5 days/week. The subjects ran 17 km/week at normal pace (— 75% VO2max), with the remaining 7 km/week as intervals and weekly 5 km races ( — 95 % VOmax). The percentage of weekly distance performed as intervals and 5 km races was approximately the same during RT(29 %) and BT(26 %).
Statistical analysis: All measures are expressed
as mean SE. Repeated measures analysis of variance (ANOVA) was used to identify differences between the dependant variables. Specific mean differences were identified using a Newman-Keuls post-hoc test. The level of significance was P < 0.05. There were no significant differences between any measures during the 4 weeks of BT; results were, thus, averaged and compared with each week of RT. Results
To insure adherance to RT, subjects under-
Resting Testosterone, Cortisol, Creatine Kinase, and Plasma Volume
stood that monetary reward for participation in the study would be witheld if there was any deviation. The subjects were
reminded to maintain BT and RT during testing and by telephone calls. The runners were also required to periodically report to the laboratory before and after training. We felt that these safeguards insured that all subjects followed the BT and RT schedules.
Testing Procedures
Resting total testosterone, cortisol, and the tes-
tosterone/cortisol ratio were not altered with RT (Table 2). Total CK levels decreased significantly (P < 0.001) during all 3 weeks of RT as compared to BT (Fig. 1). Plasma volume decreased slightly, but significantly, as compared to BT, (P < 0.01) by 5.6 1.3 % at RT week 3. Since hemoconcentration did not confound the data (Table 2, Fig. I), the results presented are not corrected for hemoconcentration at RT week 3.
Weekly Testing: Each subject was tested at the same time (0600—0900 hrs) on the same day of each week to ac-
count for diurnal variation in hormone responses (14,21). The subjects reported to the laboratory 0.5—1 hr after waking and an overnight fast. Subjects had not exercised in the previous 12 hrs. After the subjects had remained seated for 20 mm, a blood sample (— 10 ml) was drawn from an antecubital vein. No anticipatory rise in cortisol occurs in this setting, as demonstrated in other studies (18, 30). A portion of the blood sample was im-
mediately analyzed for hemoglobin (cyanmethemoglobin) and hematrocrit (microcentrifugation) for the determination of percent changes in plasma volume (PV) (11). The remainder was placed in a sterile collection tube and allowed to clot. The blood was then centrifuged, separated, and stored at —80 °C
Anthropometic Measures and Maximal Oxygen Consumption There were no significant differences in body weight (kg) during RT (mean for 3 weeks, 62.5 2.1) versus BT (62.2 2.0). Percent body fat (9.6 1.1 for BT versus 9.6 0.9 for RT week 3) was not affected by RT. Aerobic capacity, as indicated by VO2max, was not altered with RT 1.1 versus 60.9 1.2 ml/kg/min for BT and RT week (61.8 3, respectively). Body fat and aerobic capacity, therefore, did not influence the blood measures obtained in this study. Discussion
for subsequent analysis. Serum cortisol was determined by solid-phase radioimmunoassay (RIA) using a commercially available test kit (NML, Organon Teknika Corp. Irving, TX), which had minimal cross-reactivity (< 10%) with cortisol analogs. Total testosterone was also determined by using a solid-phase RIA kit (Radioassay Systems Labs, INC:, Carson, CA), with minimal cross-reactivity (
