The Effects of Supraphysiologic Doses of Testosterone on Muscle Size and Strength...
http://www.nejm.org/doi/full/10.1056/NEJM199607043350101#t=articleResults
Well, this is the study I have in mind. Trust me, I hate reading studies as much as the next person. They often have flaws that become apparent once you take a very close look at the methodology. I can name a dozen flaws that encompass SO MANY studies.
1. Conducted on animals and elaborated to humans.
2. Small sample size.
3. Indicating an "association" as tantamount to causation.
4. Sampling method biases/recruitment method biases.
5. Weak correlation.
6. Non-replicable results.
7. Neglecting to control for confounding variables.
8. Projecting findings taken in vitro and ex vivo to in vivo.
9. Samples that are representative of a specific population being extrapolated to populations for which they are not representative.
10. Measurement errors.
11. Improper administration including giving cues and suggestions.
12. Tampering with results.
13. Inability to ensure participants' compliance with study design.
I'm sure there are more issues I can imagine on a case by case basis, but these are some I can think right off the top of my head.
That said, the study I linked above is probably not immune to all of these problems. However, it does address some of the biggest problems; namely, this study was conducted on humans and there were human controls. That means a lot to me. Also, take a look at who commissioned the study. Is it a supplement research company... no. I always ask myself, what would the study authors/sponsors stand to gain, given the results they have presented. Call it cynical, but money corrupts most people.
In this case (my own wording),
the results show that taking "600 mg of testosterone enanthate in sesame oil" and no exercise, each week for 10 weeks, induces greater gains ["fat free mass"](muscle) than taking intramuscular placebo and exercise each week for 10 weeks.
In plain english: there were four groups (hereafter the group #s are labeled in no particular order and with no significance or relation to specific naming convention(s) in the study)
Group 1. Placebo and no exercise.
Group 2. Placebo and exercise.
Group 3. Testosterone and no exercise.
Group 4. Testosterone and exercise.
[Group 1.] "Fat-free mass did not change significantly in the group assigned to placebo but no exercise"
[Group 2.] "...those in the placebo-plus-exercise group had an increase of 1.9 kg."
[Group 3.] "The men treated with testosterone but no exercise had an increase of 3.2 kg in fat-free mass..."
[Group 4.] "The increase in the testosterone-plus-exercise group was substantially greater (averaging 6.1 kg). The percentage of body fat did not change significantly in any group (data not shown)."
TO MAKE A LONG STORY SHORT.
NO EXERCISE AND NO GEAR OVER TEN WEEKS = ~0 lbs muscle increase/decrease
EXERCISE AND NO GEAR OVER TEN WEEKS = ~4 lbs muscle increase
NO EXERCISE AND GEAR OVER TEN WEEKS = ~7 lbs muscle increase
EXERCISE AND GEAR OVER TEN WEEKS = ~13.5 lbs muscle increase