Increasing muscle size for appearance or performance is a common motivation to weight train. Increased muscle mass is associated with increased muscular strength, which can enhance the performance of power and strength athletes such as American football players and powerlifters.1 Another important benefit of building muscle is to stave off the effects of age-related muscle loss. This article aims to give a basic introduction on how to increase muscle size.
How Do Our Muscles Get Bigger?
Our muscles get bigger or hypertrophy when they are subjected to an overload stimulus (physical stress), which results in microscopic muscle-building events. This process leads to an increase in size and amount of the contractile elements of muscle fibers. The cumulative increase in size of many individual muscle fibers leads to a greater cross-sectional area of the actual muscle.
Hypertrophy is also associated with increased fluid and sugar (glycogen) stores in the muscles.2 This does not contribute directly to muscle force production but adds additional size.
Weight training is an effective way to stimulate anabolic (muscle-building) cellular pathways and potentially magnify the anabolic effect of hormones on muscle.
To optimize weight training as a tool for hypertrophy we need to apply sufficient stress on the muscle. The weight trainer must pay attention to several factors including frequency, intensity, volume, exercise selection, rest interval, muscular failure and repetition speed.2,3
Traditionally, it is believed that significant hypertrophy does not begin until after the first 6-7 weeks of weight training; however, significant increases in muscle volume can be realized as early as 2-5 weeks.3 In my experience noticeable size changes take time (6-8 weeks).
To optimize hypertrophy in beginners evidence suggests that, 2-3 exercise sessions a week should be performed for each muscle group.3 Although a variety of frequencies have been shown to induce hypertrophy, I have not found an agreed upon standard for the advanced trainer.4 In my experience, 1-2 times a week seems to be sufficient.
Keep in mind that in many training programs, muscles such as the shoulders are being stimulated not only on “shoulder day” but also on “chest day”.
Generally 75-80% of 1-repetition max (1RM) or 6-12 repetitions is suggested for hypertrophy training.2,3 Other rep ranges can result in hypertrophy but may not maximize gains.4
Higher volume (sets and reps) is ideal for building muscle size.2 Greater physical stress is realized from increased volume, but over-training can be a problem. Programming in 1-6 sets a session per muscle group would be effective for muscle gain.3 This could be tapered up and down, depending on a host of factors such as recovery, sleep and nutrition.
Both multi-joint and single-joint exercises should be used.2,4 An example of a multi-joint exercise would be the squat, and a single joint exercise would be the knee extension. The squat involves a large number of muscles, but certain muscles may not be adequately stimulated. By using single-joint exercises, underrepresented muscles can be developed further.
Training the muscles from a variety of angles could be important as certain portions of muscles may be more active at different angles. For example, the lower portion of the chest is involved to a greater extent in the decline bench press than the incline.6
Rest intervals can be divided into several categories: short (<30 seconds), moderate (60-90seconds) and long (>3 minutes).2 Shorter rest periods are good for inducing metabolic stress, which is what we want to stimulate hypertrophy.2,7 The problem is that it may not be long enough to allow for strength to recover between sets. It takes around a minute to recover most of our strength capacity.2 A moderate rest period would allow a balance between hypertrophy-inducing metabolic stress and recovery of strength. Longer rest periods allow for full recovery of strength capacity but decreased metabolic stress.8
An example of training to muscular failure would be when a weight trainer is no longer able to lift a load. For instance, having lifted nine reps, the trainer cannot lift the tenth, and a spotter must help. This type of training is probably good to use in moderation. When training to failure, more muscle fibers are stimulated and increased metabolic stress likely leads to an increased hypertrophic response.2
When we lift a weight there are two basic phases of the lift. There is a concentric lift (think pushing the barbell up in a bench press) and the eccentric lift (think lowering the barbell). The speed at which we lift the weight may have an effect on hypertrophy.
Lifting a weight too slowly in repetition lifting may not be optimal for muscle gain; on the other hand, lifting too quickly may not provide enough stress to the muscles. During the lifting/concentric phase of the contraction, a fast to moderate speed is probably ideal.2,3 The lowering/eccentric phase should be slower, as this is associated with greater muscle trauma and muscle-building cellular events.2
A suitable repetition speed may be 1-2 seconds for concentric/lifting and 2-4 seconds for the eccentric/lowering contraction.
Example Shoulder Workout
Barbell Overhead Press 2 x 6-12 repetitions (1-2 seconds concentric/2-4 seconds eccentric)
Side Raises 2 x 6-12 repetitions (1-2 seconds concentric/2-4 seconds eccentric)
Cable Rear Raises 2 x 6-12 repetitions (1-2 seconds concentric/2-4 seconds eccentric)
To maximize hypertrophy shoulders may be trained 2-3 times a week, with changes and substitution of exercises, grips, and angles of pull. Rest between sets would be 60-90 seconds. It would also be a good idea to work in some sets to failure, depending on your recovery abilities.
How to use this Information
Muscle building can be worked into a strength-building program, a program aimed at aesthetics, or a way to decrease muscle loss as we get older. A man/woman who wants to have rounder, more shapely shoulders may want to perform the sample shoulder program provided. A football player or powerlifter may add this type of training to their strength/power program knowing that increased muscle size is associated with increased strength. Somebody over the age of 35 may just want to limit muscle loss as they age.
Please be mindful that this is meant only as an introduction to the basics of muscle building. Many factors play a role in how an individual responds to training.
In most instances, hypertrophy training is best utilized to complement focused strength building.