The number of reps depends on your goals and preferences. Many athletes train with heavy weight within 4-6 repetitions, while fitness enthusiasts do somewhere between 6-12 repetitions to achieve muscle hypertrophy. If you want to pump your muscles you need to do 12 or more reps.
Depending on your goals, you can select one of the following options:
1-6 reps = strength
6-8 reps = balance between strength and hypertrophy
8-10 reps = hypertrophy and some strength
10-12 reps = hypertrophy and some endurance
12-15 reps = durability and some hypertrophy
15-20 reps = durability
If you are satisfied with the size of your muscles or you practice sport in which you need more power, I recommend to go for the option with the least repetition. This type of series is extremely demanding - suitable for more advanced athletes, as it requires a perfect technique to prevent injuries in the joints.
Those of you who want to increase muscle mass, I recommend to stay in the range of 6-12 repetitions. Rest 60 to 90 seconds after each series
If you want to improve your endurance, do between 12-20 repetitions. Since the goal is endurance, do not overdo the breaks between sets - no more than 30-60 seconds.
Can we combine the advantages of the different methods?
When you want to combine the advantages of different methods to achieve both strength and muscle growth, you should do series with a different number of reps.
The first option is for a week to focus on muscle hypertrophy and in the next - to train for more strength.
The second option is to use the fitness pyramid method in which the weight increase in each round, reducing the reps. It is best to give yourself some range. For example, 3 sets of 8-12 reps. This way you will know when the time has come to put more weight without overtraining.
First week: 50 kg - 8 reps.
Second week: 50 kg - 9 reps.
Third week: 50 kg - 10 reps.
Fourth week: 50 kg - 12 reps. (time to increase the weight)
Fifth week: 55 kg – 8 reps.
Do more reps mean greater fat loss?
Numerous repetitions will help you burn more fat, but will definitely make your strength training workout less effective. Try to fit most of the time in the range of hypertrophy (8-12 reps). Remember that we burn fat when we are in a calorie deficit. If you frequently overdo with reps you will burn a lot of your muscles, which slows metabolism. Therefore, it is pointless to do more than 20 repetitions per session, and in most cases, 20 are more than you need!