Testosterone: Relationship Between Dose & Gains

Conclusion: linear relationship between dose, test levels and muscle size, but declining relationship in terms of strength, with 600mg per week resulting in a very modest 5% increase in strength over 300mg per week.

Full article: http://www.physiology.org/doi/full/10.1152/ajpendo.2001.281.6.e1172

The administration of the GnRH agonist plus graded doses of testosterone resulted in mean nadir testosterone concentrations of 253, 306, 542, 1,345, and 2,370 ng/dl at the 25-, 50-, 125-, 300-, and 600-mg doses, respectively.

OK, nothing surprising here. You inject a dose of Test and you have a corresponding spike in Test in the body.

However...

The leg press strength did not change significantly in the 25- and 125-mg-dose groups but increased significantly in those receiving the 50-, 300-, and 600-mg doses (Table 5). The changes in leg press strength correlated with log testosterone levels during treatment (r = 0.48, P = 0.0005, Fig. 2) and changes in muscle volume (r = 0.54,P = 0.003) and fat-free mass (r = 0.74,P < 0.0001).

Table 5 - those at 300mg and 600mg had a significant change from baseline in terms of leg press kg - improvements of 72.2kg and 76.5kg respectively. And a huge jump compared to 125mg with an improvement of only 18.8kg. What's most surprising is the similarity at 300mg and 600mg. The higher dose didn't have a linear relationship with strength, at all.

However, the 600mg dose did display significant increases in muscle size. Table 4 shows that at 600mg users experienced 150% growth in comparison to users at 300mg, and is linear in doses higher than 125mg.

So, larger muscles at the higher dose, but only marginally more strength. I graphed this out based on the results, and while it's not perfect because of the sample size, feel like it might help this message be better communicated.

  1. Change in Strength at different doses
  2. Change in Muscle Size at different doses