This week we’re going back to 1997 for Maffet et al. study on shoulder muscle firing patterns. In this study, the researchers wanted to see how the muscles in the shoulder work during a windmill-style softball pitch. They used eight healthy college-aged women who pitched at a competitive level. To measure which muscles were being used, the scientists placed small electrodes on and in the shoulder muscles to record when and how strongly they fired. Each pitcher threw several full-effort pitches while the researchers recorded the muscle activity along with video to match the timing of the pitch to the muscle firing. The focus was on six main shoulder muscles that help control movement and protect the joint. They found:
- Different muscles were active during different phases of the pitching motion.
- The biceps were most active at the beginning of the arm circle, helping lift the arm.
- The deltoid muscles fired as the arm moved around and up.
- The rotator cuff muscles (supraspinatus, infraspinatus, subscapularis) worked hard to stabilize the shoulder as the arm rotated.
- The pectoralis major became most active right before the ball release to generate power.
- Muscle firing overlapped a lot, showing that several muscles worked together to control and protect the shoulder through the motion.
Implications: The researchers explained that pitching underhand in softball puts unique demands on the shoulder, different from overhand throwing. Even though the motion looks smooth, the muscles have to work in a very coordinated way to both create power and protect the joint from injury. The study showed that the rotator cuff and larger shoulder muscles work together at different points in the pitch, which helps explain why softball pitchers can throw so many pitches without the same injury rates seen in baseball pitchers. However, the study also pointed out that if this careful muscle balance is disrupted—such as by fatigue or weakness—pitchers could be at risk for shoulder injuries.
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We are now into fall training and for most that means gaining muscle. This is a good post regarding some simple eccentric muscle building exercises that can help throwers of all sorts. I am starting to like a lot of the posts from Alex Simone.
