How Type 2 are You?

Our skeletal muscle is made up of two fiber types. Type 1 (slow twitch) and Type 2 (fast twitch). Our muscle fiber type may influence what sports we are naturally good at or whether we are fast or strong. Olympic athletes tend to fall into sports that match their genetic makeup. Olympic sprinters have been shown to possess about 80 percent fast twitch fibers, while those who excel in marathons tend to have 80 percent slow twitch fibers. Keep in mind that genetic differences may be dramatic at the elite levels of athletic competition. But following the principles of conditioning can dramatically improve personal performance of a typical athlete.

With consistent endurance training, muscle fibers can develop more and improve their ability to cope with and adapt to the stress of exercise. Fiber type is part of a great athlete's success, but it alone is a poor predictor of performance. There are many other factors that go into determining athleticism, including mental preparedness, proper nutrition and hydration, getting enough rest, and having appropriate equipment and conditioning.

Andersen, JL; Schjerling, P; Saltin, B. Muscle, Genes and Athletic Performance. Scientific American. 9/2000

Thayer R, Collins J, Noble EG, Taylor AW. A decade of aerobic endurance training: histological evidence for fiber type transformation. Journal of Sports Medicine & Phys Fitness. 2000 Dec;40(4).