Protein Metabolization
http://www.ncbi.nlm.nih.gov/pubmed/11255140
Muscle Fibers
In general, it appears that type II muscle fibers have a greater growth potential than type I muscle fibers, as a result of long-term programs of resistance training. This has led most experts to recommend focusing on type II muscle fiber types in resistance-training for hypertrophy. However, as Ogborn and Schoenfeld (2014) have explained, type I muscle fibers can also be developed in order to maximize the overall increase in size of a muscle. Moreover, there are some very preliminary indications from some (Campos et al. 2002; Mitchell et al. 2012) but not all (Schuenke et al. 2012) studies that training with higher repetitions and low loads in order to target type I muscle fibers may lead to preferential growth of these fibers (see review by Ogborn and Schoenfeld, 2014).
Hypertrophy-Specific Training is a training method designed specifically to cause muscle hypertrophy (growth). Although significant increases in strength are often experienced while using HST, the program is not centered around strength gains.
HST is based on principles of muscle growth that have been demonstrated in recent research. In light of current published research, it would be incorrect to say “we don’t know how muscle grows in response to training.” Yes, we do! The whole point of HST is to present the body of research that explains how hypertrophy occurs and the method of training that we can derive from this research.
As we go over these hypertrophy principles, you’ll notice that you’ll already be familiar with several of them. This should come as no surprise. After all, though our understanding of muscle growth has expanded, our tools in the gym remain the same. When all that we know about how muscle cells grow is laid out on the table, a picture begins to emerge. HST, I believe, is that picture.
You might be thinking all this sounds a bit presumptuous, or at least pretty cocky. Well, the principles of hypertrophy were gathered, a method was tailored accordingly, and the results speak for themselves. What’s most interesting is that much of the positive HST feedback comes from people who’ve made serious gains even after years of training. Guys training naturally usually gain about five to eight pounds during their first HST cycle.
Mechanical load is necessary to induce muscle hypertrophy. This mechanism involves, but isn’t limited to: calcineurin, satellite cells, growth factors, calcium, and a number of other fairly well-understood factors associated with tissue strain. So, the primary stimulus for muscle-fiber growth is the physical effects of loading the muscle (lifting and lowering a weight), not the “effort” required to lift or lower it.
You may be wondering how in the world you’re supposed to focus on the load and not on the effort it takes to lift it. To better understand the principle of mechanical load, keep in mind that fatigue (or exhaustion) isn’t inseparably linked to the effect of load on muscle growth. Lifting a weight doesn’t have to make you tired in order to make you grow; it only has to be heavy enough to strain the muscle tissue a bit.
So in the gym, you needn’t focus only on how tired you are to judge whether you’ve had an effective workout. Instead, focus on whether you’re lifting more than you did the last time you trained that muscle. If you are, your workout will be effective.
References:
1: Nosaka K, Newton M. Repeated Eccentric Exercise Bouts Do Not Exacerbate Muscle Damage and Repair. J Strength Cond Res. 2002 Feb;16(1):117-122.
2: Nosaka K, Newton M. Concentric or eccentric training effect on eccentric exercise-induced muscle damage. Med Sci Sports Exerc. 2002 Jan.
3: Proske U, Morgan DL. Muscle damage from eccentric exercise: mechanism, mechanical signs, adaptation and clinical applications. J Physiol. 2001 Dec 1;537(Pt 2):333-45.
4: Nosaka K, Newton M, Sacco P. Responses of human elbow flexor muscles to electrically stimulated forced lengthening exercise. Acta Physiol Scand. 2002 Feb;174(2):137-45.
5: Allen DG. Eccentric muscle damage: mechanisms of early reduction of force. Acta Physiol Scand. 2001 Mar;171(3):311-9.