Light weight or heavy weight ?
“Should I train with light weight and more repetitions or go heavier with a small amount of reps ?”, “ Lifting heavy will make me bulky ?”, “Doing heavy lifting is dangerous for my joints/back ?”. Or again “I do not want to look like a bodybuilder”. As a trainer, I am familiar with this type of questions and it is OK !
You can find everything and its opposite on internet and social medias so it can become confusing. So let’s be clear and simple ! Your overall health depends of your physical strength. That is a fact. There is no better treatment after an injury or a surgery than strength training to make your muscles, soft tissues, joints and bones healthy again. The point often missing is the concept of “progressive overload”.
Your body is smart, it is probably the smartest machine on this planet (robot vacuum is a good one too). Why ? Because it adapts ! When something becomes too easy for your body, it needs a stronger stress on it to be able to progress. That is progressive overload. The idea is to start with a small weight or no weight at all (Air Squat for instance) and a small volume of training and when you become able to do the mouvement more easily with a perfect form, you progressively add load, or series, or repetitions or even tempo to make your body adapts.
You will tell me, I did not answer the questions yet. Your muscle is made of fibers, and in each muscles you can find 3 different types of fibers. Muscle fibers of Type I are used during an effort on a long period of time, for example : the postural muscles or training for a long distance run. They are longer and thinner than the other ones. Fiber of Type II are divided in two smaller categories Type II a and Type II b for shorter and more intense effort. They are bigger than the fibers of Type I. So the amount of repetitions will depends of your goals and the type of fibers you want to work on. Short ranges of reps with high load target more a pure strength gain (1-5 reps), for a medium amount of repetitions (8-12) we will focus more on hypertrophy and if your goal is muscle endurance, it is advised in the literature to do longer ranges (12-20 reps).
But you can also gain the same amount of strength with long series than with the shortest ones. It does not make sense for you ? Let me explain to you ! You will have the same gain of strength on 20 repetitions with a lighter weight or with 5 reps of heavy lifting if you go to the point of exhaustion or just before. (It is not a good idea to repetitively go to failure so make sure to stop one or two reps before you can’t lift the weight up anymore.) It can be useful to know it as a trainer or just if you workout regularly that there is other ways to make gains than the traditional 10 repetitions with 75% of your RM.
And this is the moment you will use the concept of “progressive overload” : you are using a weight that challenges you (if it is difficult to perform your two last reps, you are in the right way). At a certain point this weight is not challenging you anymore, so you will add more weight to create a new adaptation and make your body stronger.
Personally I use more short or medium amount of repetitions but longer ranges are also really useful to target muscles that are difficult to feel in your training.
And why strength training will not make you bulky if you don’t want to ? Let’s discuss about it in another article. ;)