Rationale behind Rep Range recommendations - Strength vs Hypertrophy

Question

It makes no sense to me why the rep range for “hypertrophy” and body builders is according to NSCA and many other sources is 3 sets and 10-12 reps.

At the most basic level cross bridges formation determines strength, hypertrophy (muscle size), cross-sectional area and force are all and direct related.

So in theory current training recommendations for strength such as 5 x 5's would lead to a greater increase in both size and hypertrophy.

Assuming all major factors to be equal (diet, rest, volume load etc.) How does that recommendation make sense? What am I missing?

(Related research is always a huge plus) – thanks!

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UPDATE: Just read that study. He definitely makes some great points. The article is literally what quite a number of strength training foundations are based on.

HOWEVER -- he draws some very BROAD conclusions and at times selectively uses one way data to provide single sided explanations to support what have been adopted as industry standards. IMO crazy we place so much weight on certain aspects of his findings....

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UPDATE #2 The 3-5 min just provides more recovery time so you're moving more weight per rep and avoiding muscular endurance training (nothing too earth shattering) - glycogen obviously is replenished to a greater degree the longer you rest.

The study below talks about the same range for power. No study would be complete if it did end by contradicting itself -- 30-60 sec is best if according to the last paragraph.

I guess it's too idealistic to expect a clear rep range (there are too many factors to take into account). I also don't agree with their recommendation to rest 3-5 min for power in favor of a shorter rest time. If it's used for sport specific training, not exactly a realistic timeframe to rest vs game scenarios. Even in a general sense; to me power based training make the most sense as a mix b/n endurance and power (for efficiency etc).

https://www.ncbi.nlm.nih.gov/pubmed/19691365

Answer 1

I did a little digging around, and I found a review article that was published in the Journal of Strength and Conditioning Research in 2010 (So relatively recent), with a full link to the PDF here.

The author went through 200+ articles to try and determine the best mechanisms for muscular hypertrophy as noted by the abstract (Emphasis mine):

Schoenfeld, BJ. The mechanisms of muscle hypertrophy and their application to resistance training. J Strength Cond Res 24(10): 2857-2875, 2010-The quest to increase lean body mass is widely pursued by those who lift weights. Research is lacking, however, as to the best approach for maximizing exercise-induced muscle growth. Bodybuilders generally train with moderate loads and fairly short rest intervals that induce high amounts of metabolic stress. Powerlifters, on the other hand, routinely train with high-intensity loads and lengthy rest periods between sets. Although both groups are known to display impressive muscularity, it is not clear which method is superior for hypertrophic gains. It has been shown that many factors mediate the hypertrophic process and that mechanical tension, muscle damage, and metabolic stress all can play a role in exercise-induced muscle growth. Therefore, the purpose of this paper is twofold: (a) to extensively review the literature as to the mechanisms of muscle hypertrophy and their application to exercise training and (b) to draw conclusions from the research as to the optimal protocol for maximizing muscle growth.

As a conclusion, the author determined after the reviews that the apparent optimal workout routine should have the following points:

• Reps should be in the range of 6-12 reps
• 60 to 90 second rest intervals between sets
• Multiplanar, multiangled exercises to give maximal stimulation of all muscle fibers (i.e. flat, incline, decline, fly for chest)
• Multiple sets should be done in a split training routine
• Some sets should be carried out to concentric muscle failure
• Concentric repetitions done moderate/fast (1 to 3 sec)
• Eccentric repetitions done slower (2 to 4 sec)
• Hypertrophy phase should culminate in a brief period of higher-volume overreaching followed by a taper to allow for supercompensation.

The linked article also gives all the papers that he researched to come up with these conclusions. I have not gone through the list to determine the validity of all the studies.

I am still looking for a similar study for pure strength gains as opposed to hypertrophic gains.