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Bulk vs. Strength: Your 5-minute Guide to Optimal Muscular Hypertrophy | BridgeAthletic

Posted by Megan Fischer-Colbrie on Feb 20, 2015 11:07:00 AM

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I was recently approached by an athlete who asked me how to put on more muscle mass. He wanted to bulk up a little bit, and was curious to know how his strength program could accommodate this goal. My usual response to this is, “Do you want to get stronger, or really just bulk up?” for how you define your fitness goals usually affects the end result. Athletes and non-athletes alike should seek to build strength, in which hypertrophy can be a happy byproduct, over bulk. Since these terms are often used interchangeably, let’s take a look at how to distinguish them to fit your strength goals.

You Can’t Ignore Your Genes

You can try to put on mass, and try to achieve that coveted muscle tone through hard work and commitment to a strength program, but the fact remains that no matter who you are, genetics play a large role in determining your muscular composition. If mom and dad don’t express the genes for these traits, then you’ll be fighting an uphill battle to achieve a particular degree of muscular mass or tone. That is one reason why distinguishing between building strength and building muscle size is so key to athletes. Not all athletes will experience significant muscle hypertrophy, but all athletes who progress through proper strength training will get stronger. Some individuals are genetically prone to putting on muscle mass quickly, while others become more defined but may not experience a visible change in size. What matters is the degree of strength an athlete obtains relative to his or her bodyweight. As this value increases, performance skyrockets.

Building for Bulk

Rarely is it useful for athletes or exercise enthusiasts to build muscle tissue for “bulk”. When this is a primary goal, the increase in size is not accompanied by a concomitant increase in strength. Building for bulk employs the use of higher reps and lower resistance in the weight room. Think of your muscle tissue as being comprised of many fibers, or strands of rope. Together, a high density of strands will add up to a much stronger rope. When you build for bulk, you actually increase the fluid in the space between the strands, inflating the size of the muscle without increasing its contractile capacity. This is known as sarcoplasmic hypertrophy, common in bodybuilding, in which high-volume training boosts the sarcoplasmic fluid in the muscle. Individuals with this high-volume profile will have little increase in strength but a significant increase in muscle endurance due to an increase in mitochondria.

Building for Strength

Let’s take the opposite example. Building for strength and peak power will lead to an increase in the density of muscle fibers (strands of rope) in your tissue, thereby increasing the strength of contraction of your muscles.  This is known as myofibrillar hypertrophy, in which the contractile unit of the muscle gets stronger and larger, ultimately leading to greater force production. Exercises with fewer repetitions and higher resistance trigger this form of hypertrophy. They increase the functional muscle tissue (the fiber density) without changing the non-functional muscle tissue (the volume of sarcoplasmic fluid).

An Integrated Approach

Now it may make more sense to see a smaller power-lifter squat heavier than a bodybuilder who showcases larger muscles. Like many concepts in sport, however, strength and size are not mutually exclusive. A proper strength program will usually begin with a phase of high-volume/low resistance exercises to increase muscle endurance, and transition later in the season to power lifting, because both elements are necessary in athletic performance. In fact, the mitochondria (produced in the endurance phase) help stimulate protein synthesis in the muscle. When power lifting produces more muscle fibers than the mitochondria can keep up with, protein synthesis can halt. It becomes clear that a healthy strength program will balance both of these strategies to deliver positive changes in performance.  


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While the bulk vs. strength debate is entwined, building for strength should remain the end goal. If you want to learn more about designing your own successful strength program or how BridgeAthletic puts it all together, visit us here. Check out our blog to dispel more myths about your exercise physiology.

Topics: Performance Trends