Here's a list of effective supps for stimulating muscle growth
Bicarbonate
-300-500mg/kg weight/day.
Creatine
- laoding dose 20g/day for 5 days - 5g maintainace (or just let it build up over time in your system at 5g flat (do not take with sugar, or pre-mixed in "special" formulas ( a con) - you can get an insulin boost from the food you eat (so just take it with meals.
HMB-1.5g-3g/day
Protein and amino acid mixtures- 1.6-1.7g/kg day
Replenishing DEFICIENCIES of essential minerals (magnesi.um,zinc) 450mg magnesium and 30mg zinc/day
-Others (less evidence)
1.Antioxidants 9N-acetyl-L-cysteine, ascorbate, caretenoids,coenzyme Q10, gluthione, lipoic acid, soy isoflavones, elenium, tocopherols and combos)
2. Caffeine (green tea an excellent choice - detoxifies liver and kidneys, reduces LDL cholesterol, enhances mood, produces alpha wave patterns in the brain aiding concentration (high lycine content) and does not raise BP like other forms of caffeine (6 cups per day reccomended)
3. L-carnite
4. CLA
5. l-Glutamine and L-Ornathine-alpha-ketoglutarate (OKG)
6.Herbals (e.g. Eleutherococcus,Panax Gingseng, Rhodiola, longax)
7.***** 3 fatty acids (flax seed oil/ hemp oil / soy bean oil good choices)
8. Vitamin C
Of courese there are drugs that cannot be detected in drugs tests that boost strength/muscle mass and improve rbc count. These are either difficult or impossible to detect, have short half lifes, so are out of the system quickly. There are alsO masking drugs.
It is impossible to test for EPO, insulin or Growth hormone - the last 2 working together to potentiate huge gains.
Final point, athletes should primarily be looking to improve power and strength without gaining too much muscle. It is important to keep your power to weight ratio as high as possible (but this is sport dependent - e.g a rugby prop may not be too concerned by this, but a weight class limited powerlifter/ boxer or 400m runner would.
Creatine is of course the most effecting supplement availiable for gaining muscle mass (I'm sure you know about the action on ADP-ATP synthesi via improved phosphate pool), combined with dragging water molecules into the muscle (Malate/ribose show similar promise via different mechanisms).
In truth, most supplements (taken on their own) do not make a big difference. BUT, if taken in combination - they can provide additive effects.
Other supps, protect your health and boost imunity - if you are ill less often, you will be able to gain more muscle.