For gaining muscle, you usually have to do between 8-15 reps with multiple sets. My problem is, for example, if I do close grip chin ups in my first set cleanly and without cheating 8 reps, and, as I progress to next sets with 1-1, 30 min rest between each sets, I can't do the exact amounts of reps which I did in first set. And, it will fall to 4-5 reps in 3rd or 4th set (because of lack of energy) and it will be changed from hypertrophy to strength. So, what do you suggest? Should I cheat in last sets in order to hit the first set's rep range, or, should I increase my rest time? Will it preserve it's hypertrophy effect?
First, let me correct your understanding of hypertrophy:
- You get bigger by more fatigue inducing reps (see this article for more info)
- There's nothing inspired or sacred about rep ranges or even set targets. They are just tools (see this article for more info)
Second, you need to understand the concept of fatigue. The articles I linked to above are excellent places to start, but there's some other foundational information:
- Your body uses Adenosine Triphosphate (ATP) to generate force
- When ATP is consumed, the byproduct is Adenosine Diphosphate (ADP)
- Creatine (naturally existing protein) can then react with most ADP and turn it back to ATP. This process takes roughly 2 minutes to complete.
- When your creatine reserves are exhausted, your body has to resort to much less efficient means to fuel your training
NOTE: taking creatine as a supplement will increase the reserves you have, allowing you to train longer. The affects like most supplements are marginal, but present. If you have a creatine deficiency, more common in vegetarians, creatine supplementation will have a much more noticeable impact.
The bottom line is that when you are targeting As Many Reps As Possible (AMRAP) in each set, your body can only recover so quickly. Even if you extended your rest periods to 2 minutes, you'll still lose reps from set to set.
Fatigue as a training variable
It's not uncommon to intentionally run fatigued in training. Some of the benefits include:
- Increased training efficiency (less time to do the same work)
- Increased cardiovascular training
- Lifting in a fatigued state can cause more muscle micro-tears, which in turn get repaired into bigger/stronger muscle
The only way to have your last set have the same number of reps as your first set is to stop your first set before failure.
Answering your questions directly
what do you suggest? Should I cheat in last sets in order to hit the first set's rep range, or, should I increase my rest time?
Just keep training the way you are training. There's no need for the symmetry between each set. Only resort to cheat reps when there is a specific training reason to do it. If you can't come up with it, then just work on increasing the total number of reps over time.
Will it preserve it's hypertrophy effect?
The hypertrophy affect happens because you demand more of your muscles today than you did yesterday. If you increase your total reps, or add resistance (i.e. more weight), or do the same work in less time, you are keeping the hypertrophy affect.
Also understand that if you never demand more of your body, it will never grow beyond your initial demands. Just focus on increasing the demands a little at a time, and your muscles will grow. It doesn't matter if you are doing several sets with the same number of reps, or if the reps decrease each set.
It's quite common to have too short rest periods between sets, so increasing it will lower the effect you are noticing. The effect won't vanish however, I would suggest that you set your goal like 10 reps, 8 reps, 6 reps (3 sets), that way, you will challenge yourself in every set instead of just the last ones.
In exercises where you are able to decrease the amount of weight, do that instead, if you want to keep the number of reps the same. For chins, use a rubber band or do negative reps instead.