I think its a good idea to point out aswell failure in HST isnt the point where you can no longer lift the weight anymore, it is technical failure when your form starts to suffer, from the FAQ:
"Since rep speed deteriorates before technical breakdown, end a set when a rep is noticeably slower than the first. So - if you slow down, you STOP. This ensures that you stay at a safe rep number short of failure."
Also as totentanz said, because your Max's are determined before you start, by the time you've reached them you may well be stronger anyway so they may no longer be your maximum weights.
Heres a whole load of information as to why it isnt necessary to train to failure atall for hypertrophy that i found very helpful:
<div></div><div id="QUOTEHEAD">QUOTE</div><div id="QUOTE">The conventional notion is that you must work to momentary muscular failure before all fiber types will receive a growth stimulus. The mechanical load principle, however, states that all muscle fiber types participate when the muscles are exposed to heavy enough loads. Recruitment patterns involved in lifting weights heavy enough to cause hypertrophy activate all fibers, both fast and slow
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Inducing fatigue is a principle specific to endurance. "Load" and "muscle tension," on the other hand, are principles specific to hypertrophy. Further, methods based on fatigue/exhaustion (training to failure and rest/pause stuff) are really methods of increasing strength (CNS adaptations). There’s nothing wrong with this, but by inducing more fatigue, you’ll have to train less frequently as the CNS can take a week to recover.
Keep in mind that "failure" is an indicator of central fatigue, not muscle strain. If you want to increase your resistance to fatigue, train to failure all the time. If you're only interested in effectively straining the muscle so that it'll get bigger, just focus on that and get past the idea that you have to go all out on every set.
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It is commonly misunderstood that muscle failure is the stimulus for muscle growth. Intuitively, it makes sense. How can someone not sustain growth if they are working to the very limits of their capacity? Unfortunately, this is not true! The tension (load) on the muscle is what actually causes growth, especially during the eccentric action of the rep. One can go to failure, yet the load can still be too light to induce hypertrophy. See Hortobagyi T, Hill JP, Houmard JA, Fraser DD, & colleagues. Adaptive responses to muscle lengthening and shortening in humans. J. Appl. Physiol. 80(3): 765-772, 1996 “…eccentric muscle actions are associated with greater neural adaptation and muscle hypertrophy than concentric exercise”
Also, see Warren GL, Hayes DA, Lowe DA, Armstrong RB. Mechanical factors in the initiation of eccentric contraction-induced injury in rat soleus muscle. J Physiol. 1993 May;464:457-75 “These data support the hypothesis that eccentric contraction-induced injury is initiated by mechanical factors, with muscle tension playing the dominant role”
If progressive load, rather than chronic fatigue, is the primary stimulus for tissue hypertrophy, it isn’t necessary to “train to failure” if hypertrophy is the objective. This makes the practice of “adding more weight only after you can do more reps” terribly inefficient if muscle growth is the goal. It also refutes the logic of the “muscle confusion” practice, which is primarily a neurological phenomenon.
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HST does not require that you train to failure because that prevents you from training frequently enough. It’s better to train according to the recovery of the muscle (48 hours) than according to the CNS (up to a week or longer).
"Failure" is an indication of exhuastion, not activation. A motor unit can be activated without failing. If the weight is heavy enough, all motor units will participate.
Yes, the reason you avoid training to failure and especially using "forced reps" is to avoid undue CNS drain. After all, "fatigue" is not what makes you grow. Taining to exhaustion only delays your next workout, thus slowing your ability to grow. However, if strength is your goal rather than growth, you should "generally" be using a 2/week schedule rather than 3/week anyway. I say general because it changes as fatigue should be periodized.
Training to failure during an HST cycle will not make you any stronger than stopping short of failure. If you are concerned with strength, take weeks 7 and 8 to work on strength. Reduce the number of exercises and do more sets. Delay the next workout 1 day if you begin to fall behind in CNS recovery.
As for training to "failure" begin required to elevate protein synthesis, it isn't. Training to failure is a neurological issue, not a metabolic issue.
The reason subjects train to failure in most training studies is because that's the only way they know how to judge effort. Once the subject can lift his/her 10RM 12 times (just an example) they increase the weight.
Again, as the weight gets heavier, the ability to achieve sufficient time under tension diminishes. It’s simply too heavy to support long enough. On the other hand, increasing volume will quickly diminish the amount of weight you can use. Not only that, but as you increase volume or begin to train to failure, you also increase the amount of time it takes the CNS to recover (see Int J Sports Med. 2003 Aug;24(6):410-8). But don't forget that the CNS does adapt to different levels of volume. This is what traditional “Periodization” is all about.
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For one, it does not allow for more frequent training. Secondly, when training to failure, you are not really working the muscle(s) to a greater degree, just taxing the CNS. The bodybuilding community is the only one that lends any credence to HIT. Olympic lifters and elite strength athletes have been performing squats, deadlifts, bench, etc. several times per week for decades now. The BB community is just THAT far behind. The influence of steroids is a major contrubuting factor. </div>
