Many people believe that lifting a heavy weight for low repetitions and lifting a lighter weight for high repetitions requires the same level of effort from the body. This is totally incorrect. To measure the level of effort in weight training we have a formula called as ‘per rep max’. This stands for the amount of maximum repetitions that a particular weight will allow. For example, if you were to take a weight with which you would hit failure on the 16th rep, then you are said to be training at an intensity of a 15 rep max.
If you choose a weight that does not allow you to do more than 1 repetition despite all your effort, then you are said to be training at a 1-Rep Max intensity which is considered the Zenith of intensity. This kind of effort is extremely demanding on your musculoskeletal system and your central nervous system. As you start using weights that allow you to do more repetitions, the demands placed on the body, especially on the central nervous system, are less taxing and therefore lower on the intensity scale. A low rep max set, such as a 6-rep max is a lot more effective at causing muscle wear and tear and increasing strength than a higher rep max set.
What is the place of high rep training??
An intelligent question to ask here would be that if the sole purpose of weight training is to increase strength performance & Hypertrophy induced by wear and tear at the cellular level and if a lower rep max, such as a 6-rep max set is more effective than 15-rep max sets then what is the significance of high rep training?
The purpose of high rep training has been largely misunderstood. Some wrongly believe that high rep training builds muscular endurance. Muscular endurance is only needed in endurance events where the number of repetitions done by the skeletal muscles involved in that endurance activity go into multiples of 100 in just one session (e.g. a session on cross trainer). Doing 25-30 rep sets is not going to equip the muscles with the endurance required to last through an endurance activity. When you strength train, the best way to get the most out of your training is to go with low rep max sets (6-8 rep max sets).
The other misconception related to high rep training is that it imparts a fat burning effect that contributes to a more muscular or defined body. Again, nothing could be further from the truth. To get definition, you require 2 things – muscular development and fat loss. You are aware that weight training causes fat loss via the EPOC effect and the extent of EPOC depends on two things – Intensity and the area of damage. The higher the intensity (low rep max), the more the micro trauma and thus more repair work leading to greater EPOC. The lower the intensity (high rep max), less the micro trauma and conversely less intense is the EPOC. Thus, if you want to get defined or muscular train intensely with heavy weights that offer you no more than 6-8 reps. (Obviously coupled with a proper diet plan).
Low rep max High Intensity, heavy training requires the human body to have gone through central nervous system (CNS) adaptation.
Our body has to learn all movements in weight training so that the body instinctively, without thinking, moulds itself into the correct form and technique. If the body has not learnt the movement, and the central nervous system adaptation has not occurred, then the body is bound to get injured using heavy weights.
For example, to use outdoor cycling as a mode of cardiorespiratory exercise, you first have to learn cycling. Similarly, you first have to learn swimming to be able to use it as a cardiorespiratory exercise. If you attempt to swim without knowing how to swim you are bound to drown. So, every beginner must start weight training using high rep max weights that allow him 15-20 reps. This is his learning phase, at such a low intensity whenever the trainer corrects his form he is in a position to process the information and make necessary changes in the positioning of his body. The low intensity also minimizes the risk of injury due to bad form. As he practises with high reps his CNS is slowly adapting to the movements. High rep training is simply a means of creating CNS adaptation so that one uses perfect form and technique while using heavy weights without even having to think about it.
The difference between a low rep max and a high rep max set is exactly the same as the difference between running and walking. Beginners walk in their endurance programs then graduate on to brisk walking, then to jogging and then on to running and some advanced athletes even use sprinting. In a similar fashion, beginners in weight training start out at 15-20 rep max, then move on to 12-15 rep max (intermediates), then on to 6-8rep max (Advanced) . It's like swimming or cycling, once you learn it you can do it without thinking about it and that's when you can swim or cycle fast.
Now since it is clear that a lower rep max set is better in all respects to a higher rep max set, the question arises – Why not just zap the muscles with 1-rep max sets? The answer is fairly simple. The overload is just too much for the body's recovery abilities to handle. It is too much intensity. All good things in excess turn bad.