# Does cardio lower testosterone?



## BillytK03 (Dec 7, 2006)

does intense cardio lower testosterone even when accompanied with strength training?


----------



## DontStop (Dec 7, 2006)

the only thing i can see lowering your testosterone is "roids"


----------



## Risiko (Dec 8, 2006)

...

I thought roids raises testosterone...


----------



## kcoleman (Dec 8, 2006)

Risiko said:


> ...
> 
> I thought roids raises testosterone...



Taking steroids can shut down or lower your body's natural testosterone production. Test levels can also drop if you weighttrein for too long, like > an hour. That's why they say short, intense sessions of weight training is best, like 30 minutes.


----------



## JimSnow (Dec 8, 2006)

I suspect most pro bodybuilders have destroyed their bodies' ability to produce testosterone at all.


The conventional wisdom is intense, short and well-structured programs w/ plenty of rest and variation... at least for us "natural" atheletes. And cardio, in my estimation, is no different. It's part of the program.

I'm 45... I crap out all my testosterone in the morning.


Running on Fumes Jim.


----------



## mike456 (Dec 8, 2006)

kcoleman said:


> Taking steroids can shut down or lower your body's natural testosterone production. Test levels can also drop if you weighttrein for too long, like > an hour. That's why they say short, intense sessions of weight training is best, like 30 minutes.



where have you been?


----------



## P-funk (Dec 8, 2006)

Like Kcoleman said, training intensly for prolonged periods of time will lead to declines in test levels and elevations in cortisol leves.

As far as endurance training....here are some things I found:
*
Reproducibility of low resting testosterone concentrations in endurance trained men.*

Gulledge TP, Hackney AC., Eur J Appl Physiol Occup Physiol. 1996;73(6):582-3. 


Previous reports indicate endurance trained (ET) men have low resting testosterone concentrations without any significant increases in their luteinizing hormone (LH) concentrations. The purpose of this study was to examine the reproducibility of these resting hormonal findings in ET men. Resting blood samples were collected at three separate trials (2 weeks apart) in groups of ET men (n = 15) and age-matched, untrained (UT, n = 13) men. Blood specimens were analyzed for total testosterone, LH, cortisol and prolactin. Results indicated that testosterone was significantly (p < 0.01) lower in ET than UT at each of the three trials. LH, cortisol, and prolactin were not different (p > 0.05) between the groups at any trial. These results confirm earlier findings reported for ET men. Furthermore, the results indicate the resting reproductive hormonal status (i.e., low testosterone) of ET men is reproducible and does not appear to be an artifact of the timing of the blood sampling methodology used.

*Basal reproductive hormonal profiles are altered in endurance trained men.*

Hackney AC, Fahrner CL, Gulledge TP., J Sports Med Phys Fitness. 1998 Jun;38(2):138-41. 

OBJECTIVE: The purpose was to examine the basal reproductive hormonal profiles in age-matched groups of endurance trained (ET) and sedentary (SED) men under controlled conditions. EXPERIMENTAL DESIGN: Resting basal blood samples were obtained from groups of ET and SED men after a 24-hr control period. Blood specimens were analyzed for testosterone (T), free-testosterone (fT), sex-hormone binding globulin (SHBG), luteinizing hormone (LH), cortisol, and prolactin. The design of the study was retrospective and cross-sectional in nature. SETTING: Laboratory setting at the University of North Carolina, North Carolina USA. PARTICIPANTS: ET men (n = 53) who had been involved with chronic endurance exercise training for > or = 5 years. SED men (n = 35) were selected of comparable ages and the fact that they had done no formal exercise training. RESULTS: Results indicated that the basal T and fT of the ET men were significantly (p < 0.01) lower than that of the SED men. The levels of these hormones in the ET men where in the normal clinical range, but represented only 55% to 85% of those seen in the SED men. For SHBG, LH, cortisol, and prolactin, no significant differences (p > 0.05) were found between the ET and SED men. CONCLUSIONS: ET men have lowered basal T and fT levels and this suppression may be related to an alteration in the hypothalamic-pituitary-testicular regulatory axis since the LH of the ET was not elevated. Whether these hormonal changes have any significant beneficial (i.e., protective cardiovascular) or negative (i.e., decrease anabolic-androgenic processes) physiologic consequences remains to be determined.

*Reproductive hormonal profiles of endurance-trained and untrained males.*

Hackney AC, Sinning WE, Bruot BC., Med Sci Sports Exerc. 1988 Feb;20(1):60-5. 

This study compares the resting reproductive hormonal profiles of untrained (N = 11) and endurance-trained (N = 11) males. Testosterone, free testosterone, estradiol, luteinizing hormone (LH), prolactin, and cortisol were measured by radioimmunoassay in resting blood samples (8 h fast) collected every 60 min for 4 h. The endurance-trained group had been active for (mean +/- SE) 12.4 +/- 6.7 yr, 6.6 +/- 0.2 d.wk-1, 68.5 +/- 4.4 min.d-1, while the untrained group was sedentary. Neither group had histories of hypothalamic-pituitary-testicular disorders. The overall 4 h mean testosterone and free testosterone levels were significantly (P less than 0.05) lower in the trained group (4.99 +/- 0.46 vs 7.25 +/- 0.67 ng.ml-1, and 17.2 +/- 1.4 vs 23.6 +/- 0.6 pg.ml-1, for the trained and untrained groups, respectively). The LH of the endurance-trained group was higher (15.3 +/- 1.9 vs 11.7 +/- 1.2 mIU.ml-1, P = 0.06); however, LH pulse frequency and amplitude did not differ between groups. An enhanced estradiol feedback to the hypothalamus-pituitary could not account for the elevated LH, as estradiol levels were similar in the groups. Prolactin and cortisol levels were normal and did not differ between groups. The results suggested normal hypothalamic-pituitary function existed in the trained subjects, and prolactin and cortisol were not causative factors in the lowered resting testosterone and free testosterone levels. The findings indicate that chronic endurance training lowers testosterone and free testosterone in males possibly by impairing testicular function.

*Relationship between stress hormones and testosterone with prolonged endurance exercise.*

Daly W, Seegers CA, Rubin DA, Dobridge JD, Hackney AC., Eur J Appl Physiol. 2005 Jan;93(4):375-80. Epub 2004 Nov 20.

Previous pharmacological and pathological studies have reported negative relationships between circulating testosterone and certain stress hormones (i.e., cortisol and prolactin) in humans. These relationships have subsequently been used in hypotheses explaining the subclinical resting testosterone levels often found in some endurance-trained males, but as of yet no one has specifically examined these relationships as they relate to exercise. Thus, we examined the relationship between total and free testosterone levels and cortisol, and between total and free testosterone and prolactin following prolonged endurance exercise in trained males. Twenty-two endurance-trained males volunteered to run at 100% of their ventilatory threshold (VT) on a treadmill until volitional fatigue. Blood samples were taken at pre-exercise baseline (B0); volitional fatigue (F0); 30 min (F30), 60 min (F60), and 90 min (F90) into recovery; and at 24 h post-baseline (P24 h). At F0 [mean running time = 84.8 (3.8) min], exercise induced significant changes (P<0.05) from B0 in total testosterone, cortisol and prolactin. All three of these hormones were still significantly elevated at F30; but at F60 only cortisol and prolactin were greater than their respective B0 values. Free testosterone displayed no significant changes from B0 at F0, F30, or the F60 time point. At F90, neither cortisol nor prolactin was significantly different from their B0 values, but total and free testosterone were reduced significantly from B0. Cortisol, total testosterone and free testosterone at P24 h were significantly lower than their respective B0 levels. Negative relationships existed between peak cortisol response (at time F30) versus total testosterone (at F90, r=-0.53, P<0.05; and at P24 h, r=-0.60, P<0.01). There were no significant relationships between prolactin and total or free testosterone. In conclusion, the present findings give credence to the hypothesis suggesting a linkage between the low resting testosterone found in endurance-trained runners and stress hormones, with respect to cortisol.


----------



## Adamjs (Dec 8, 2006)

^ P - where is the dumbed down crib notes you always give at the end of your posts along the lines of: 

"so in otherwords endurance training lowers testosterone which is why marathon runners are piss-weak and don't look like strength athletes and strength athletes don't do marathon running."


----------



## P-funk (Dec 9, 2006)

Adamjs said:


> ^ P - where is the dumbed down crib notes you always give at the end of your posts along the lines of:
> *
> "so in otherwords endurance training lowers testosterone which is why marathon runners are piss-weak and don't look like strength athletes and strength athletes don't do marathon running."*



lol...that sounds pretty good.


----------



## Sexybeast777 (Dec 10, 2006)

That's true, marathon runners have great endurance, but they are not that strong. I have also heard that heavy squatting increases testosterone levels, is this true?


----------

