Overtrained or in the Zone? Tests & Analyses of Samples of Athletes' Saliva Shall Help Determine Objective Criteria

Could something as simple as a saliva test tell you if you or your clients are overtraining? I mean, common sense would dictate that cortisol, free T and IL-6 should tell us something.

Salivary testosterone, cortisol, and interleukin-6, those are the three parameters Travis Anderson and colleagues had on their list of candidates when they conducted their latest study at the University of North Carolina (Anderson. 2016).

As you will remember from previous articles I wrote about overtraining. The only decently reliable method of seeing it coming is to assess you heart rate variability. On the other hand, athletes who are complaining of general fatigue and decreasing performances in the latter phase of their overtraining, when the symptoms become often almost unbearable, will also show high cortisol, low free testosterone and increased IL-6 levels.
It is thus only logical that the scientists assumed that it would be possible to evaluate the (overtraining) response of 20 moderate-to-highly trained young men to a standardized 6-week pre-season workout by the means of the said three parameters.

For this purpose, each subject was assessed at six separate sessions, next to their body composition, the scientists also measured the subjects' individual Recovery-Stress by the means of the standardized Recovery-Stress Questionnaire. In conjunction with the orally administered hormone / cytokine tests (always at 15:00-17:00 h) and the independently recorded training intensities and volumes (that was done by the researchers, not the subjects) on the bench, the back squat and the Olympic-style clean (+ auxiliary movements, see Table 1 | total session length including warm-up 45-60 minutes) these measurements were the basis for the scientists analysis.

Table 1: Overview of the primary and auxiliary exercises in the std. RT protocol (Anderson. 2016).

To make the subjects more overtraining-prone, the scientists kept gradually increasing the training load and began adding in conditioning runs to the workouts from week two on. The latter were done immediately after the RT workouts and consisted of 100 or 300m runs, of which the latter were replaced in week five with a speed/agility circuit that lasted another whopping 45 minutes.

Figure 1: Cortisol, IL-6 and free testosterone (left axes) and body weight (blue, right axis) development (Anderson. 2016).

As you may see with some surprise, the subjects' weight knew only one direction. Unfortunately, the body fat and lean muscle data was either only measured at baseline or simply omitted from the respective table, which holds nothing but the weight information.

Since the subjects' performance on all the prime movers increased significantly, though, we can assume that at least some of these gains were muscle - and that in spite of the significant reduction of the free testosterone / cortisol ratio and the skyrocketing IL-6 levels.

Table 2: REST-Q score by affective category (Anderson. 2016); * denotes sign. difference from baseline (p < 0.05); values for the score range from 1 = low anger, depression, etc. to 5 = high anger, depression, etc.

For the latter, it is, by the way, easy to see that the thing that "hurt" the trainees the most was the late addition of the agility work (another 45 minutes of intense aerobic workouts | -20% free T, +110% cortisol, +600% IL-6 |  note: this is in line with previous studies showing that aerobic exercise is more likely to result in overtraining than anaerobic training). Strength training alone (week 1) and combined with the sprints (weeks 2-4), on the other hand, didn't affect the alleged anabolism gauge, the testosterone / cortisol ratio, significantly.

Based on both the accepted physiological (weight, performance) and psychological (REST-Q) the subjects were, as the authors rightly point out "not symptomatic of overtraining". A conclusion that leaves us with the question...
References:

• Anderson, Travis, Et Al. "Changes in Resting Salivary Testosterone, Cortisol and Interleukin-6 as Biomarkers of Overtraining." Sport And Health (2016): 2.
• Robson-Ansley, Paula J., Andrew Blannin, and Michael Gleeson. "Elevated plasma interleukin-6 levels in trained male triathletes following an acute period of intense interval training." European journal of applied physiology 99.4 (2007): 353-360.