A lot of people, myself included, have at one time or another underestimated the complexity behind achieving muscular hypertrophy (growth). While many view the process in a simplistic light, the fact is that the entire sequence involves the individual muscle fibers of each muscle interacting with satellite cells, the immune system, growth factors and various hormones to produce structural changes such as an increase in myofibrils and sarcoplasm (Wilmore & Costill, 1999). Far from simple, right?
Considering there are entire books written on this process, it would be impossible to do the topic due justice in a single post. Instead, my goal will be to break down the concept of hypertrophy into a simple 3-step process that should be enough for anyone to go out and begin building muscle. From there, we’ll be able to pick up things like growth factors, fiber types, etc and create a more complete picture as we go.
ACME: Muscle Growth Kit …
While the exact process of muscle growth is still a mystery in many ways, popular belief currently breaks hypertrophy into three stages:
Stimulus – Recovery – Growth
These steps form a feedback loop which, if implemented, should form a continuous pattern leading to ongoing gains.
Step 1: Stimulus
When muscles are used they adapt to change, plain and simple. These changes will depend on the type of activity, load exerted, duration of the contraction, etc. (Marieb, 2004). Muscle hypertrophy occurs primarily through continual anaerobic, high-intensity resistance activity, such as that which occurs during weight training. According to Fleck and Kraemer (2004), resistance training causes neural adaptations, which produce first changes in endurance and strength and eventually, the size of the muscle. Conventional wisdom states that, to allow these adaptations to take place, muscle hypertrophy requires ‘progressive overload’. In other words, as your body adapts and begins to find your weight, set and rep range less demanding, you must increase the intensity of the training by up-regulating one of the three mentioned factors in order to continue to build bigger and stronger muscles.
Recently, several studies have emerged which have found that pushing a muscle to the point of failure using lighter weights stimulates the same amount of muscle protein synthesis as using heavy-loads. These have given some grounding to the benefits of employing ‘low-intensity’ resistance training methods for achieving hypertrophy (Burd et al., 2012). However, this research was focused purely on muscle hypertrophy, ignoring the strength aspect of the training. For increases in both size AND STRENGTH, traditional high-intensity, heavy-load exercises still reign supreme.
Step 2: Recovery
Recovery is just as important as training. Particularly when you’re a beginner, ensure that you allow your body adequate time to rest, repair and rebuild muscle. Also, the greater the stress of the workout, the greater the overall muscle recruitment – leading to an increased need for longer recovery time. Rhea (2003) concluded that for untrained individuals, a frequency of 3 days per week, per muscle group is optimal. For trained individuals, a frequency of 2 days per week, per muscle group is ideal. Naturally, this will depend on volume, individual training status as well as your goals (i.e. whether you’re training for size, strength, endurance, etc). An additional consideration is that compound, multi-joint movements such as deadlift, squat, etc will require more rest due to the increase in motor unit recruitment, and extra stress placed on the Central Nervous System.
Step 3: Growth
The final step is the one that everyone aims for. This is the result you’ve been seeking – an increase in overall lean body mass & size. But don’t get complacent … Your body is EXTREMELY adaptable and is always trying to return to a state of homeostasis (balance). As such, you must keep varying weight, sets and rep ranges. This will CHALLENGE your body, place it under new and greater stress and lead to continued progress. The next step? Return to Step 1 of the progress, and REPEAT THE CYCLE AD INFINITUM!
References:
Marieb, E. N. (2004). Human anatomy & physiology (6th ed.). San Francisco, CA, USA: Pearson Benjamin Cummings.
Wilmore, J.H. and D. L. Costill. Physiology of Sport and Exercise (2nd Edition).Champaign, IL: Human Kinetics, 1999.
Fleck, S. J. & Kraemer, W. J. (2004). Designing Resistance Training Programs (3rd ed.). Champaign, Illinois, USA: Human Kinetics.
Nicholas A. Burd, Cameron J. Mitchell, Tyler A. Churchward-Venne, Stuart M. Phillips. (2012). Bigger weights may not beget bigger muscles: evidence from acute muscle protein synthetic responses after resistance exercise. Applied Physiology, Nutrition, and Metabolism, DOI: 10.1139/h2012-022
Rhea, M.R., Alvar, B.A., Burkett, L.N., & Ball S.D. (2003). A meta-analysis to determine the dose response for strength development. Medicine and Science in Sports and Exercise, 35(3):456-464.
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