Purpose To measure the rate at which muscles fatigue (tire) under different conditions. Materials Skills - Choose Your Own Stress Fundamentals - Why do Muscles Grow Tired? Graph Paper Test tube holders (1) or Clothespin Textbooks (2) -- used as a weight in Stress B and D Notebook Paper Watch or clock with second hand

Little League Pitcher Curacao Willemstad Courtesy USA Today

Background

Over use causes between 30-50% of all injuries seen in young teens. The process starts when a repeated motion weakens either bone or tendon. Little-league-elbow is an overuse injury that is very common in young baseball players. To prevent such an injury, teens should not throw more than 80-100 pitches in a week. Also they should not throw more than 1,000 pitches in a year.

You have volunteered to be the trainer of a Babe Ruth League baseball team. Your starting pitcher has a really bad pain in his pitching arm, but he doesn't want to miss his next start. When you look at his pitch count for the week you see that he has already thrown 110 pitches. You have no choice; he has to rest his arm.

You know that when muscles are tight and cold they are more likely to suffer overuse injury. But your pitchers already warm up by throwing a few practice pitches before they face a batter. You have decided to do an experiment. Does warming muscles before an activity slow the process of muscle fatigue or does it add to it? Is it better to warm a muscle by doing the same activity or by doing a different activity?

Procedure

• Read Fundamentals - Why do Muscles Grow Tired?
• Work together with two or three other trainers to perform the experiments listed in the Skills - Choose Your Own Stress.
• Examine data looking for patterns that indicate possible answers to the questions.

Conclusion

Based on team data, which condition causes muscles to tire the most? Write a training plan suggesting ways to prevent overuse injuries in young teens. Your plan should include at least 3 strategies with supporting data.

 

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This activity was developed by the Event-Based Science Institute with generous support from the Cal Ripken, Sr. Foundation. A teacher version of this and all other baseball/biology activities is available free from the Institute. This Muscle Fatigue activity was was written by Susan Fazio, science teacher at Tilden Middle School, North Bethesda, MD.