Question: Will my muscles get bigger if I lift weights?
Answer:
Hypertrophy (increasing muscle mass) depends on three factors: genetics, gender, and training intensity.
Genetics primarily dictates muscle fiber type – people with more fast-twitch fibers acquire larger muscles more easily than people with predominantly slow-twitch fibers. Fast-twitch fibers use anaerobic metabolism to create fuel and fatigue more quickly than slow-twitch fibers. Slow-twitch fibers are more efficient at using oxygen to generate fuel which sustains muscle contractions over a longer time.
Males acquire larger muscles than females due to greater amounts testosterone and other sex hormones that influence protein metabolism.
Training intensity is the only controllable factor. In the case of resistance training, intensity can be altered by controlling the load on the muscle (ie. the amount of weight that is lifted). To stimulate an increase in muscle mass, the muscle must be over loaded. For someone who is just beginning a resistance training program, this may occur by lifting a load that is 60 percent of the one-repetition maximum (the maximum amount of weight that can be lifted in a single repetition). Someone who has been lifting for a time and wishes to increase muscle size will need to increase the load to at least 80 percent of the one-rep max.
There are many factors that determine whether someone will get larger muscles by lifting weights. Each individual’s body will respond to the resistance in a unique way depending on their gender, genetic make-up, and specifics of their training regimen. Navigating this complex equation can be challenging at times and will require patience, consistency, and often, some trial and error. A personal trainer can guide you through this process and help find what works best for your body.
Adapted from:
IDEA, Health and Fitness Association. (2013). Top 10 Most Frequently Asked Questions in a Fitness Center. Retrieved on July 1, 2014 from https://www.ideafit.com/fitness-library/top-10-most-frequently-asked-questions-in-a-fitness-center-and-their-answers
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