I haven't seen evidence that exercise has a significant effect on the metabolism of testosterone, which occurs mainly in the liver. This study found long-term resistance training had no effect. "No changes were observed in T metabolism due to [resistance training] indicating a homeostatic stability for this hormone in men of different ages." Metabolism is the primary factor influencing your average serum (free) testosterone on a particular dosing schedule. However, exercise can affect the rate of absorption by increasing blood flow, etc. This changes the observed half-life of the testosterone delivery method. If the dosing interval is short relative to the half-life then the decrease in half-life caused by exercise would have little effect. For example, on daily injections of testosterone cypionate you probably wouldn't notice any changes; serum testosterone would remain constant. However, testosterone pellets might be implanted only every few months, which is on the order of the half-life. Therefore, when the half-life is reduced by exercise, serum testosterone is higher in the first part of the cycle and lower in the last part. Total testosterone absorbed and used is the same across different half-lives.
