I am 52 and last year started down the road to TRT. My levels were 350, with natural supplements it increased to 450. Of course my Dr. said that was good enough, even though I still suffered all the symptoms of low test. I kept pushing because despite my increased level my Free Test never changed, which was a 47, the lowest of the lab scale for normal. After a tripped to an Urologist they agreed I needed TRT. I am not superman now, but feel a whole lot better. I have always exercised and in great shape, so that was not an issue. I have lost 8-10lbs, without any changes in diet since starting. I take a 200mg injection every 3 weeks; I tried the Gel for 2 months with no benefit. Current injection have me in the 700 range and 100 on the Free.
Bottom line your free testosterone is what you body is actually absorbing and using. If it is low it does not matter what your total testosterone level is.