Fit to Play with Jim Johnson: Fast twitch softball 

  • Jim Johnson

  • The high school softball season is well underway throughout Western Massachuestts. Here’s a shot from Frontier Regional earlier this season. STAFF FILE PHOTO/PAUL FRANZ

Published: 5/9/2022 4:28:02 PM
Modified: 5/9/2022 4:28:01 PM

A few years back I had the misfortune of being in the emergency room at Cooley Dickinson Hospital. As I was leaving I saw several pairs of cleats sticking out of various curtains. I asked the emergency room physician about this and he said, “Softball started today. This happens every year.” Interestingly, I recognized two of the players who had been recently jogging around the Smith College track, presumably to get in shape for softball.

I suspect that people are occasionally mistaken when they say they are playing slow pitch softball, but the slow part actually ends the moment the ball leaves the pitcher’s hand. After that, all of the action occurs in short spurts; that action is fast and short. Softball is a fast twitch, anaerobic sport. Jogging is not part of softball; in fact a slow repetitive activity like jogging is the antithesis of softball. Some studies show that the more you jog, the slower you get.

Unfortunately, some of these players suffered injuries that prevented them from enjoying a season of softball. There is the occasional broken arm in softball, but most injuries are to soft tissue, like ligaments and muscles. Sprained knees, ankles, torn hamstrings, and strained elbows all take time to heal. Most of these injuries can be prevented by proper preparation. Participating in a pre-season conditioning program will not only reduce injury, you will also play better. But you cannot just rely on pre-season conditioning to stay healthy; conditioning activities should be conducted throughout the season.

The basic principle of injury prevention is to analyze the requirements of the activity, then design exercises that will specifically train the body to perform those activities in competition. Almost all sports have a significant anaerobic component and the pre-season should address that demand. Softball is a high velocity sport, involving running at top speed, either from a standing start or while turning. Quick stops are often required. Running, catching, and then throwing at high speed is not unusual. Batting requires a vigorous rotation of the trunk in order to maximize bat velocity.

To prepare for softball, not only do you need to replicate the activities, you have to train the specific muscle fibers within the muscle. Most people have heard or read that we have different types of muscle fibers. Within each muscle is a combination of slow and fast twitch muscle fibers. These muscles are recruited, called upon, for different activities. Slow twitch fibers develop less tension and more slowly. Slow twitch fibers have a good blood supply and great endurance. Fast twitch fibers are larger, develop tension quickly and with greater force. Fast twitch fibers are mostly anaerobic and fatigue quickly.

Fast twitch fibers require a higher neurological stimulus, a signal that results in a short powerful contraction. Running may use your leg muscles but only sprinting actually uses the fast twitch fibers within the muscle. Playing catch in the front yard may warm your shoulder and arm muscles, but only high speed throwing really recruits the fast twitch fibers.

Your goal in pre-season is to prepare yourself for high-speed action, but make sure you don’t hurt yourself in pre-season. High-speed activities are not part of normal life, or even normal workouts, so start slowly and always warm up prior to conditioning drills as well as games. The warm up is one of the best things you can do to prevent injury.

Use your own intuition and experience to replicate softball activities like sprinting and throwing. Remember you are not ready to run full speed or throw all out in the beginning; build up to this, training 2-3 times a week for about 30 minutes. You should be ready after only a few weeks.

The hamstring muscles require special attention. Hamstring tears are particularly problematic and common in softball, and the injury tends to recur. The hamstrings are complicated because they cross the hip and knee joint. Running at high speed requires intricate timing. Research shows that the hamstrings often tear as the knee is rapidly extending as the hamstrings are lengthening but exerting tension to slow down the extending knee. The Nordic hamstring curl prepares you for this action. Watch it on YouTube, but it requires a partner to hold your ankles while you sway forward from a kneeling position during which the hamstrings exert tension while lengthening. Like all new exercises, start slowly, allowing your hamstrings to adapt.

Jim Johnson is a retired professor of exercise and sport science after teaching 52 years at Smith College and Washington University in St. Louis. He comments about sport, exercise, and sports medicine. He can be reached at

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