Quote[/b] ]In order of importance:
1) Satellite cells must be activated, differentiated, and fuse with existing fibers, donating their nuclei.
2) Mechanical stress must be transmitted to the sarcolemma (mechanotransduction) and contractile protein structures within the sarcomeres. This will trigger focal adhesion kinases (FAK) that in turn initiate the downstream signaling events leading to an increase the contractile and cytoskeletal protein expression/synthesis.
3) pH and oxidative stress must be acutely increased within the muscle fiber.
Focusing just on the workout, this pretty much sums it up. If #1 doesn’t happen, you will not grow…ever. If number two doesn’t happen, you will grow a little, but you will soon reach the limits of the sarcoplasmic/nuclear ratio and growth will stop. If #3 doesn’t happen, you will still grow quite significantly, but the rate of growth might be enhanced or facilitated if #3 is achieved.
#1 is achieved when a certain level of microtrauma is experienced by the fibers. This is brought about by load, eccentric contractions, and to a much lesser extent, hypoxia (A.K.A. #3) When load, eccentric contractions and #3 occur, each fiber will produce and release muscle specific-IGF-1 (sometimes called mechano-growth factor) The IGF-1 in turn seeps out of leaky sarcolemmas and acts on nescient satellite cells to initiate #1. Microtrauma is rapidly reduced from workout to workout (Repeated bout effect) thereby limiting the effectiveness of any given load to induce further hypertrophy.
#2 is achieved by loading a muscle that is actively contracting.
#3 is achieved by contracting a muscle (doing reps) until you create an oxygen deficit and subsequent hypoxic byproducts (e.g. lactate and oxygen radicals).
The afore mentioned physiological principles of muscle growth are what we follow in order to ensure that 1,2 and 3 happen.
1 set is not necessarily "better" than 3 sets.
As far as muscle hypertrophy is concerned, high duration of load is best. The cellular signals that are initiated by strain on the structural and contractile proteins of the cell are increased as time under load increases. If it weren't for the involvement of fatigue in performing the actual reps and sets, you would be better off doing tons of sets and reps.
HST uses lower numbers of sets because the muscle is trained much more often. So, the muscle isn't actually loaded for less time, its just that the loading is more evenly spread out over time to keep the signal more constant. If there are any factors that allow a person to do more sets per workout, he/she should do them.
From what other research there is on the time course of genetic expression in response to overload, it is clear that we don’t even come close the amount of time needed to elicit the greatest hypertrophic effect. But what are you going to do? We have to lift the weight a lower it over and over in order to overload the muscle. From the overload research, I personally feel longer time under tension is better. But you have to balance that with CNS fatigue, and absolute load.
More sets with heavier weight is better than fewer sets with less weight. But there is a limit to our exercise tolerance. So you have to figure out a way to get as much loading of the muscle as you can, as often as you can, and still be able to constantly increase the load over time, without burning out or getting injured.
Keep in mind that HST does not dictate that the total volume (i.e. number of sets per body part) over the course of the week should be lower than what a person is accustomed to using with traditional routines. HST only advises that the volume be evenly distributed over more workouts in the same time period. So if you are used to doing 9 sets for back on "back day" using a traditional routine (e.g. training each body part once per week), HST would have you do 3 sets at a time for 3 different workouts.
Obviously, a guy who is used to doing something like 12 sets for back once per week, is not going to gain much by dropping to doing only 1 set for back even if it is 3 times per week. He went from 12 sets to 3 sets per week. Not only that, but HST would have him use submax weights most of the time where he is obviously plateaued and used to doing 100% max weights (Not true 100%, but 100% with the fatigue that inevitably accumulates by the 3rd set). This is just too great a reduction in training to provide him with significant gains. The key here of course is Strategic Deconditioning, that would then allow him to begin growing again, with less "average" weight and volume, but higher frequency.
Well, for me, 2 sets is enough on most bopdyparts. But then again, with body parts like back, I will usually do 3 sets at different angles of pull and grip widths.
But the amount of volume each person is used to varies. I am not saying that you have to train to your volume limit. I'm just saying that if 1 set isn't enough, do another. Do too much and you'll begin to get progressively weaker, and/or injured and you will lose your desire to train.
At first, you won't know how much is too much and how much is too little. So, start with 1 work set per body part per exercise, and work up from there.
Sometimes, you will find that you need to do more during the lighter workouts, and fewer sets during the heavier workouts. I hate to say this, but play it by ear, while you stick to the principles. You have to learn what it feels like. You have to actually experience growth from a series of workouts to be able to associate the specific feeling of "enough" work with subsequent growth.
all I am going to do is post an excerpt from Bryan in the FAQ, this really sums it up well.
