How many times can you open and close a clothespin in one minute? Two?
Paper and Pencil to Record Data
- Hold a spring-loaded clothespin between your thumb and index finger.
- Start a timer and count how many times you can open and close it in one minute.
- When your minute is up, DON’T STOP! See how many times you can open and close it during the second full minute.
- Once the second full minute is over, record your numbers for minute one and minute two.
Which minute were you able to open and close the clothespin more?
How It Works:
Did you slow down significantly during your second minute? This quick experiment displays how your muscles get the energy they need to function. When you were opening and closing the clothespin, your muscles were exercising anaerobically, drawing on their stores of glycogen to produce the adenosine triphosphate (ATP) molecules that supply the energy they needed to contract. As the glycogen ran out, your muscles ran low on ATP and their ability to contract decreased. If you squeeze the clothespin slowly, you’re exercising aerobically. In aerobic exercise, your muscles also draw on oxygen and the glucose and fatty acids carried in by the blood to produce ATP. Your ability to keep exercising aerobically depends on the delivery of oxygen and fuel molecules (glucose and fatty acids) to your muscles. And that depends on your circulation and respiration.
Lactic acid is what causes muscles to burn after strenuous exercise.
To create more ATP, your body needs extra oxygen, so breathing increases and your heart starts pumping more blood to your muscles.