Clothespin and Muscle Fatigue Prelab In order to contract (move), your muscles require energy in the form of ATP. (Adenosine Triphosphate) Muscles can produce ATP by using oxygen (aerobic respiration) or no oxygen (anaerobic respiration). Anerobic respiration in muscles cells produces lactic acid. When muscles do a lot of work quickly, the buildup of lactic acid reduces their ability to contract, until eventually exhaustion sets in and contraction stops altogether. This is called fatigue. Prelab Questions (Answer these questions on a separate sheet of paper and staple to the data table handout) 1. 2. 3. 4.

What is the type of energy that a muscle needs in order to contract? What is produced when there is no oxygen present for the muscle cells? When muscles use oxygen, what form of respiration is this? What causes muscle fatigue?

Lab: 1. Hold a clothespin between the thumb and index finger of your dominant hand (the one you use the most) 2. Count the number of times you can open and close the clothespin in 30 seconds, while holding the other fingers of the hand straight out. Make sure to squeeze quickly and completely to get the maximum number of squeezes for each trial. 3. Record the results in the data table 4. Repeat the process for nine more times, recording the number of squeezes. 5. Do not rest between trials. 6. Repeat steps 1-5 with your nondominant hand. Lab Questions: (Answer these questions on a separate sheet of paper and staple to the data table handout) 1. What happened to your strength as you progressed through each trial? 2. Describe how your hand and fingers felt near the end of your trial? 3. Were your results different for the dominant and the nondominant hand? If yes, explain why? 4. Why did your muscles become weak and fatigued?

Name:____________________________ _______________ Period________________

Clothespin and Muscle Fatigue DATA TABLE (Circle your dominant hand, ie. Are you right or left handed?) Trial 1 2 3 4 5 6 7 8 9 10

Right Hand

Left Hand

Name:____________________________ _______________ Period________________

Clothespin and Muscle Fatigue DATA TABLE (Circle your dominant hand, ie. Are you right or left handed?) Trial 1 2 3 4 5 6 7 8 9 10

Right Hand

Left Hand