Stop reading forums, pick up a physiology textbook and educate yourselves. Do a PubMed search on muscle protein synthesis in healthy, non-AAS using adult men.
I cant even believe this retarded discussion is still going.
Unlike the tendons and ligaments, studies have shown that muscle responds by adapting after a period of several weeks or even months of progressive loading (McDough & Davies, 1984). It also should be noted that the protein turnover rate in collagen occurs approximately every 1000 days.
In a healthy male NOT taking steroids, your rate of skeletal muscle hypertrophy is not going to exceed what your connective tissues can handle. Unless you have a 1 in 5,000,000 genetic mutation that has disabled your natural signaling mechanisms for negative regulation of skeletal muscle development, you CANNOT gain pounds of muscle in one week.
Those who scoff at this and continue to believe they've gained super size over such a short period forget that much of the increased bodyweight is largely due to increased body fat stores, glycogen and water. Of course you will FEEL like you have gained 2-3 pounds of muscle, that's a phenomenon called transient hypertrophy. Basically when you are training intensely and getting sufficient nutrition, your muscles will swell with water and glycogen stores, giving them that "full" feeling. This does NOT equate to a gain in sustainable tissue.
There are so many variables in muscular development that it is not only impractical but irrational to try and develop a "standardized" rule for how much muscle tissue the human body can synthesize in a given time. Your natural build and genetics play a significant role. We DO know, however, that unless you are on some serious hormonal supplementation, even the fastest of gainers will not be putting on more than ~.5 kg of actual muscle tissue in a week. That's not including fat, water, glycogen, etc.
Here's some references to get you armchair bodybuilders started:
1. Kraemer, W.J., Adams, K., Cafarelli, E., Dudley, G.A., Dooly, C., Feigenbaum, M.S., Fleck, S.J., Franklin, B., Fry, A.C., Hoffman, J.R., Newton, R.U., Potteiger, J., Stone, M.H., Ratamess, N.A., & Triplett-McBride, T. (2002). American College of Sports Medicine position stand. Progression models in resistance training for healthy adults. Medicine and Science in Sports and Exercise, 34, 364-380
2. Paddon-Jones, D., Leveritt, M., Lonergan, A., & Abernethy, P. (2001). Adaptation to chronic eccentric exercise in humans: the influence of contraction velocity. European Journal of Applied Physiology, 285, 466-471
3. Volek, J.S., Duncan, N.D., Mazzetti, S.A., Staron, R.S., Putukian, M., Gomez, A.L, Pearson, D.R, Fink, W.J., & Kraemer WJ. (1999). Performance and muscle fiber adaptations to creatine supplementation and heavy resistance training. Medicine and Science in Sports and Exercise, 31, 1147-1156
4. McLester, J.R. Jr., Bishop, P., & Guilliams, M.E. (2000). Comparison of 1 day and 3 days per week of equal-volume resistance training in experienced subjects. Journal of Strength and Conditioning Research, 14, 273–281
5. Strauss, R.H., Lanese, R.R., & Malarkey, W.B. (1985). Weight loss in amateur wrestlers and its effect on serum testosterone levels. Journal of the American Medical Association, 254, 3337-3338
6. Forbes, G.B. (2000). Body fat content influences the body composition response to nutrition and exercise. Annals of the New York Academy of Sciences, 904, 359-365
7. Van Etten, L.M., Verstappen, F.T., & Westerterp, K.R. (1994). Effect of body build on weight-training-induced adaptations in body composition and muscular strength. Medicine and Science in Sports and Exercise, 26, 515-521
8. Candow, D.G., & Burke, D.G. (2007). Effect of short-term equal-volume resistance training with different workout frequency on muscle mass and strength in untrained men and women. Journal of Strength and Conditioning Research, 21, 204-207