Increasing the size of muscles, also known as hypertrophy, is generally achieved by progressively increasing weight and/or amount of times said weight is moved. To build muscle, 3 main things need to happen:
Mechanical tension occurs when our muscles contract against a load such as the biceps working during a barbell bicep curl. To produce tension on the muscle not only is load or resistance important, but also the time we spend moving that weight. The slower we do our reps, the longer the time under tension for those particular muscles.
While muscle damage may sound like something you want to avoid, the type of (microscopic) damage we are referring to here is essential for the growth of muscles. When you perform heavy resistance training, you are altering the structural integrity of the muscle cells. This signals to the body it needs to be more resilient to resistance.
Metabolic stress comes down to the chemical environment in your muscles during your workout. When you require energy in greater quantities than can be generated through aerobic (or oxygen) pathways, then we rely on anaerobic (non oxygen) pathways. This leads to the build-up of by-products that increase the metabolic stress on muscle cells.
Traditional strength training can and will contribute to muscle hypertrophy, especially if you’re new to heavy resistance training. However, due to the very high loads of traditional strength training and the stress it places on the nervous system, you generally lift for fewer reps and rest for much longer periods between sets. The much higher resistance requirements of true strength training also require good technique under heavy loading so if building muscle mass is your goal, we recommend going a little lighter on your lifts and focussing on repetitions between 8 and 15.
What is fairly clear is that a decent amount of volume should be moved by the muscles though-out the training session. A combination of moderate-heavy weight, low-medium reps and medium-high rest seems to be the most beneficial for hypertrophy training to keep the body in an anaerobic state of exercise. Whilst keeping in mind the number of sets and reps, the main focus should be on the amount of volume your muscles move in the session. Volume being measured by the amount of weight lifted for the selected reps and sets.
As always, consistency counts for lots as well. Consistent demands on the body produce changes in line with them. If we ask our body to move high volumes of load on a consistent basis, it will build.