Thursday, March 13, 2014

Endocrine Side-Effects of Athletic Competition: Is Power Lifting for Pussies and Canoeing for Real Men? Sports Specific Hormone Profiles - Cause or Coincidence?

With only one female power lifter and fewer female athletes for all sports, I didn't copy the hardly legible data for them, as well.
Some of you will remember the sneak peak of the results of a recent study designed to measure the "profile of hormones in a group of elite athletes" I gave you on Facebook a couple of days ago (read more). In case you do belong to the >4,500 people who already liked the SuppVersity Facebook Page, you will also remember that the observational study a group of Irish + British researchers conducted was meant to provide information about "what may be considered as normal" in a group of people among whom the use of hormones as performance-enhancing agents is widespread.

The research question M.J. Healy and colleagues from the St James’s Hospital, the Tallaght Hospital and the University of Exeter in Ireland and the UK tried to answer is thus: "What's actually normal for someone who's voluntarily exposing his body to hardships with profound endocrine side effects."
You can learn more about testosterone at the SuppVersity

High protein = low testosterone?

Low T, low life expectancy

Treat diabesity with testosterone

T-Gel + aromatase inhibitor?

D-aspartic acid does not boost T

Understanding testosterone
It goes without sayin' that the answer to this question is of particular interest for the WADA, the World Anti Doping Association. Whether it's also relevant for the average gymbro, on the other hand, is something I want to discuss in the bottom line of this article and thus after we've taken a closer look at the main results, of which the extremely low testosterone : estrogen ratio in powerlifters I already mentioned in the previously cited Facebook post is just one out of several curiosities.
Figure 1: Endocrine parameters relative to minimum (% above the bars) and maximum of reference range (bars) for men; the data is based on a barely legible table from the manuscript version and subject to correction (Healy. 2014)
Curiosities and abnormalities, of which it's often hard to tell, whether they are brought about by the certain training techniques or physical demands of the corresponding sport, or it is just the other way around, and athletes with certain baseline hormone profiles chose specific sports because their endocrine programming is particularly conducive to high performance in their specific sporting discipline.

In a totally different context, Maïmoun et al. (2014) have only recently been able to show that the endocrine profile of female swimmers "was characterized by significantly increased serum T levels (0.56 ng/mL, vs 0.39 ng/mL for controls) - to be precise, "[s]eventy-two percent of these swimmers presented T values higher than 0.5 ng/mL, characterizing this population as hyperandrogenic" (Mïmoun. 2014). A percentage that's high enough for the French researchers to conclude that...
"[...] in these female athletes is perhaps not coincidental (16). A predisposition to hyperandrogenism might orient girls toward sports like swimming, where strength is a performance criterion." (Maïmoun. 2014)
Whether a similar explanation could be given for the extremely low testosterone levels of the powerlifters is highly questionable. There is after all no sex-difference in respect to the impact and importance of testosterone in strength sports that would dictate that women need abnormally high testosterone and abnormally low estrogen levels, while men need low testosterone and high estrogen levels for maximal strength performance.

Apropos men and women: There are similar extremes

If we stick to the analysis of abnormal testosterone levels, it appears as if excursions to both extremes are about equally likely in men and women, with...
  • 16.5% of the male athletes suffering (?) from serum testosterone levels below 8.4 nmol/l, the lower limit of the normal reference range (Bayer. 2013), and 
  • 13.7% of the female athletes exposing testosterone levels greater than 2.7 nmol/l, the upper limit of the normal reference range (Bayer. 2013)
... it's obvious that "normal" is a relative term, when it comes to the "Big T" levels of  elite athletes during / after competitive events.
Doping excluded: With one exception, all athletes with low testosterone levels had normal luteinizing hormone (LH) levels - a clear indicator that they were not using performance enhancing drugs like trenbolone, or nandrolone, which would obviously crush both, the T- and LH-levels.
For the women with testosterone levels above the normal range (> 8.3nmol/l) the scientists observed significant differences in fat mass, height, estradiol fT3, fT4, %body fat, BP2, Osteocalcin and IGF-I. Specifically, the women with elevated testosterone levels were...
  • taller and thinner, 
  • had lower estradiol, IGF-1 and osteocalcin levels, but
  • increased free T3, free T4 an IGFBP2 levels
In both groups, men and women, the outliers were predominantly younger athletes. In view of the fact that there is no suitable control group or age-specific reference data in athletes, we have to be very careful about drawing far-reaching conclusions based on data from this "high T outliers".

Sport is not just one, it's the most significant determinant of endocrine disturbances

Irrespective of the fact that we have to be similarly cautious on the other end of the high vs. low testosterone level divide, the mere age-difference between the oldest athletes, the power lifters, and the youngest, the swimmers, is similarly unsuited to explain the differences I plotted in Figures 1-2 (note: I decided against plotting the data for the female athletes, because (a) the table was even harder to read and (b) the number of athletes in many sports was very low), as the height (basketball players were the tallest and the power lifters the shortest) and weight differences (contact sports like ice hockey, handball and basketball had the highest BMI while cross-country skiing the lowest). In fact, Healy et al. found only two instances where age alone could account for the differences between sports (IGF-BP2 and IGF-BP3 in women).
Figure 2: Power lifters don't even have the lowest testosterone : estrogen ratio, track & field athletes are - assuming that I deciphered their estrogen levels correctly, even worse off (Healy. 2014)
Overall, there were fewer significant differences in hormone levels between groups among the female athletes (Table 3b) but this is most likely due to the smaller numbers of volunteers in many of the groups as the pattern between sports seems quite similar. This takes us back to where we came from. As surprising as it may sound: At least in men, the predominant factor for inter-athlete differences is the category of sport the corresponding athletes are competing in. As Healy et al. point out, here are a number of recognisable patterns and many unexpected:
"For example, there was the inevitable relationship between height, weight, body fat, lean body mass (LBM) and BMI. Weight correlated very closely with BMI which in turn correlated less closely with LBM, body-fat and height. For LBM and body-fat the relationship with BMI is distinctly different between the sexes reflecting the increased body fat in women at all levels of BMI." (Healy. 2014)
And while I know that you would probably like to hear more about the underlying mechanisms, an observational study like the one at hand simply doesn't allow for a detailed analysis of the general mechanism behind this complex network of changes.
High / low testosterone not a performance factor? Because the samples were anonymized it's not possible to tell whether there significant correlations between high or low hormone levels and the overall success of the athletes in the events, but in view of the fact that all athletes, overtrained or not, successfully competed at national or international level. The study at hand does, as Healy et al. point out "indicate that serum testosterone does not determine athletic performance" and will thus add "another 'nail in the coffin' for the strange IAAF/IOC definition" of normal values for testosterone - specifically in female athletes (IOC).
Let's get back to the T:E ratio: In view of the fact that there is remarkably little information published in peer-reviewed journals concerning hormonal profiles in elite athletes. It's hard to compare the data from the study at hand to previous data in a way that would allow definite conclusions.

It is thus not clear why there are so many low testosterone values in men and why they occur particularly often in power lifters. Their body fat levels are higher than those of the other athletes, which ~17% yet still far away from those levels, where the increased aromatization (=conversion of testosterone to estrogen; learn more) becomes a problem. The psychological stress from the event should have been similar in all athletes and the physiological demands would suggest lowered testosterone levels particularly in aerobic sports, which are well-known for their association with functional hypothalamic hypogonadism, stress fractures and reduction in serum testosterone (Bennell. 1996). Moreover, even physical strain as observed in army personnel on a combat course also leads to a dramatic fall in testosterone to very low levels that recover rapidly after a good night's sleep (1978).
References:
  • Aakvaag, A., et al. "Hormonal changes in serum in young men during prolonged physical strain." European journal of applied physiology and occupational physiology 39.4 (1978): 283-291.
  • Bayer Diagnostics. Total (Serum) Testosterone by Advia Centaur System (2013). Ref Type: Online Source: labmed.ucsf.edu/labmanual/db/resource/Centaur_Testosterone.pdf  
  • Bennell, Kim L., Peter D. Brukner, and Susan A. Malcolm. "Effect of altered reproductive function and lowered testosterone levels on bone density in male endurance athletes." British journal of sports medicine 30.3 (1996): 205-208.
  • Healy, M. L., et al. "Endocrine Profiles in 693 Elite Athletes in the Post‐Competition Setting." Clinical endocrinology (2014).
  • IOC Regulations on Female Hyperandrogenism (2012). Ref Type: Internet Communication: www.olympic.org/Documents/Commissions_PDFfiles/Medical_commission/2012-06-22-IOC-Regulations-on-Female-Hyperandrogenism-eng.pdf
  • Maïmoun, Laurent, Neoklis A. Georgopoulos, and Charles Sultan. "Endocrine Disorders in Adolescent and Young Female Athletes: Impact on Growth, Menstrual Cycles, and Bone Mass Acquisition." The Journal of Clinical Endocrinology & Metabolism (2014).