A common question we trainers often get asked is what is the difference between hypertrophy and strength and why is it necessary to work on both? Hypertrophy simply put is the increase of muscle fiber size. Muscle hypertrophy should not be confused with muscle hyperplasia, which is an increase in the number of muscle fibers. Muscle hyperplasia is thought to cease at an early on during development. The increase in muscle tone one undergoes through resistance training comes primarily from hypertrophy, or the increase in muscle fiber size one already had. Strength is how much force that specific muscle or a muscle group can exert in a single effort.
Muscle hypertrophy occurs when myofibril trauma, also known as micro tears, has occurred in the trained muscle and then stimulating protein synthesis to rebuild the damaged muscle. There are two factors that are most important to muscle hypertrophy that cause micro tears. One is volume or how much work was performed that day and that week. Volume is calculated from sets, reps, and weight lifted. The second factor is time under tension. The appropriate time under tension to elicit muscle hypertrophy is between 6-12 reps. Another way of accomplishing time under tension is to add tempo to the reps i.e. performing 3 reps with a 5 second eccentric component, 1 second pause and then 3 second concentric component. When this muscle damage occurs a nearby satellite cell, a specialized cell that acts very similarly to a stem cell, will move into the damaged area. The satellite cell then acts as a nucleus that controls a specific volume of muscle. This nucleus is now able to regulate protein synthesis and other processes the muscle needs to recover and perform other actions. Protein synthesis is an anabolic process where the muscle uptakes amino acids and uses them to repair the damaged muscle by adding additional contractile proteins to the muscle.
Muscular strength occurs when the nervous system has been trained to maximally recruit motor units, which is a motor neuron and all the muscle fibers it innervates, to produce maximal force. When training for strength the emphasis is training the nervous system rather than breaking down muscle. Strength training has much lower volume and less time under tension than hypertrophy training, so the stimulus that elicits muscle growth are minimal, thus muscle hypertrophy would be minimal during this training phase. Typical rep schemes are between 1-5 reps during strength training. The act of moving heavy loads for the indicated reps is what trains the nervous system to recruit muscle in a more efficient manner. When repeated over a microcycle, the end result is that maximal force can be expressed.
Now that we understand the differences between muscle hypertrophy and muscle strength we can answer the questions from earlier. Why is it important to have both hypertrophy and strength? Simple put the bigger the muscle is the more strength it will ultimately produce, and the more strength a muscle has the heavier weight it can move for more reps. For example, if someone wants to bench a certain amount and they focused on strength for a prolonged period of time and are still not capable of benching their goal weight then the issue may be that they do not have big enough muscles to produce the necessary force to move the weight. Another example would be if someone was interested in adding muscle mass, after a while of moving the same weights around they will not be eliciting the proper stimulus to have muscle grow. If they focused on improving strength, when they came back to muscle hypertrophy they would be able to move more weight for the same number of reps as they were performing previously.
Some sports like bodybuilding and powerlifting demand different training and emphasis. Bodybuilding is all about aesthetics and muscle mass. Bodybuilders typically train for hypertrophy since the amount of force they produce is meaningless to their sport. This being said you will still see bodybuilders dropping the amount of reps they perform and work on some strength training for the same reasons stated in the previously. Powerlifters on the other hand only care about how much weight they can move and do not typically care about how they look. Most of a powerlifters training is focused on expressing their strength by training with fewer reps and heavier loads. Again, you will see powerlifters train for hypertrophy when they are far put from competition. They have to do this so they have larger muscle that can be trained to express more strength. In both sports, there is a specific emphasis, yet both training phases are necessary for maximal performance.
By: Garrett Giles, Lead Trainer