Both total testosterone:cortisol (T:C) and free testosterone:cortisol (FT:C) ratios have been studied for their association with training and overtraining heart disease risk, and a tendency toward psychological aggression. The ratios are thought to reflect the balance between anabolic (testosterone) and catabolic (cortisol) activities in the body.
The FT:C ratio is found to decrease relative to the intensity of physical or athletic training. A 30% or more decrease in FT:C after strenuous training is thought to reflect increased strain as well as a less than desirable recovery 24 hours after exercise.
A low T:C ratio may indicate an increased risk of heart disease, insulin resistance, severe sleep apnea, and increased stress.
An elevated T:C ratio appears to be associated with aggression.
We have been unable to establish optimal ranges for these but will add to this entry if and when we find something!