Question – does 3 reps, 6 reps, 12 reps or 20 reps bulk you up the fastest?
Answer – they can all bulk you up but via different ‘pathways’. However, for whatever reason, if I can only choose one, it will have to be 6 reps.
Let’s see how each can contribute to muscle growth.
Very low rep work (<6) can mainly help to increase strength quickly and have some carry over effect to higher rep work. When you do higher rep work with more weight, that leads to more muscle growth. Thus, low rep work indirectly accelerates muscle growth. On its own, it can be not very effective as there must be also enough work volume (reps x sets) in order to effectively build muscles.
Low – medium rep work (6-8) mainly increases the size and number of muscle fibres, a term called myofibrillar hypertrophy. There can also be significant increase in muscular strength. This is known to be ‘true’ muscle growth and creates a more toned and dense look.
High rep work (10-15 reps) produces sarcoplasmic hypertrophy which is basically an increase in muscle size due to increased formation of blood capillaries in the muscle and/or increased storage of fluids. This type of growth doesn’t lead to significant strength gains and cause a more ‘puffy’ look to the muscles.
Anything more than 15 reps is geared towards muscular endurance already.
For our purpose of bulking up, we really don’t care which kind of hypertrophy we get. The best is that we maximize both types – myofibrillar and sarcoplasmic hypertrophy.
Thus, we use different rep ranges to target both types of hypertrophy. A typical workout might have 3 exercises, each having a different rep range.
A sample chest workout might look like this:
1) Flat bench press – 4 sets of 6 reps (myofibrillar hypertrophy)
2) Incline dumbbell press – 3 sets of 9 reps (myofibrillar and sarcoplasmic hypertrophy)
3) Dumbbell flies – 3 sets of 12 reps (sarcoplasmic hypertrophy)
Using this principle, you can now work out the rep ranges for exercises for your other bodyparts.
Still have trouble or still not getting satisfactory results? Get yourself a professional personal trainer and see your progress skyrocket!