What You Need To Know About Muscle Fibers If You Exercise

Everyone wants to get lean, strong, powerful muscles. Few people want to understand the significance or the reasons as to how your muscles get stronger from an exercise science standpoint. Here is what you need to know about muscle fibers if you exercise. Your muscles are made up of muscle fibers that come in numerous different types. In regards to power, the important distinction is between type 1, slow-twitch, red fibers and Type 2, fast-twitch, white fibers.

Slow-Twitch Fibers

Slow-twitch fibers are red because they have a large number of capillaries, which gives it a large blood supply. They also contain more mitochondria in order to create energy and higher levels of endurance enzymes than fast-twitch fibers. Slow-twitch fibers are sluggish to react (hence the name slow-twitch) so they cannot produce great power.

It should be noted that if you give slow-twitch fibers a continuing supply of glycogen and fat for fuel, and oxygen to burn it for energy they will continue to produce low-force muscle contractions for hours. Therefore, you should consider slow-twitch fibers the endurance components of your muscles.

Fast-Twitch Fibers

On the other hand, fast-twitch fibers do the opposite. They are white because they have little blood supply. They contain more contractile proteins than slow-twitch. They also contain more glycolytic enzymes for the production of energy in the absence of oxygen, and more creatine phosphate so you can quickly regenerate ATP, which is your primary energy molecule. Ultimately, fast-twitch fibers are the power components of your muscles. 

When you think of fast-twitch fibers you should correlate it to things like sprint speed and squat jump performance. When you think of slow-twitch fibers you should think of a 10 rep overhead shoulder press. Maximum intensity exercise such as a 5-rep bench press to failure with very heavy weights would recruit many fast-twitch fibers. And they are still firing at neat maximum at the end of the set, so the growth of strength is optimized.

Fast-twtich fibers grow stronger with heavy exercise more quickly than slow-twitch fibers. So for the greatest growth of strength – the first component of athletic power- weight programs must be and should be designed to first stimulate fast-twitch muscle fibers.

Forget about the pump you get at the gym that makes you look huge for 45 minutes. This is because the muscle stuffs itself with lactic acid and blood, and grows bigger and harder. It’s hard not to love this pumped-up look, but it’s not something that benefits you long term, only for a very short duration. If you want raw power, train for fast-twitch fiber growth and watch your results soar.