Lab 8 – Analyzing Muscle Fatigue



Name ______________________________________ Period __________ Date ___________

Clothespin Lab

Background: Muscle cells rely on aerobic cellular respiration for their energy needs. When muscles are deprived of their customary oxygen, they are capable of functioning but for only a short period of time. During intense activity, oxygen is often being used by the body faster than it can be supplied to the muscle. The muscle cells will continue to function. However, they begin to obtain the necessary energy through anaerobic lactic acid fermentation. In lactic acid fermentation, your body builds up lactic acid causing your muscles to experience a burning sensation. Following a period of the rest, allowing the lactic acid to be flushed out of your muscles, the muscle cells regain their normal condition.

Materials: Spring-type clothespin, stopwatch or second hand on wall clock, graph paper, ruler, dishpan of ice water

Procedure:

PART ONE: EFFECT OF TEMPERATURE ON MUSCLE CONTRACTION

1. Prediction: Read through the procedure for part one. How do you expect your baseline data to differ from your cold data? Explain your reasoning.

2. Using your “off” hand, count the number of times you can open and close a clothespin in 30 seconds. Hold the clothespin between your thumb and index finger and hold your other fingers out straight. Try to do so as many times as you can in 30 seconds. Be sure to open and close the clothespin completely each time. Record your data in the following table as the first baseline trial.

3. Shake out your hand and allow your fingers to rest for a few seconds. Then repeat the 30 second operation with the same hand and same technique. Record your data.

4. Calculate the average of the two baseline trials. Record the average in the table.

5. Now submerge your hand in an ice water bath for one full minute.

6. After one minute, remove your hand from the ice water bath and immediately count the number of times you can open and close the clothespin in 30 seconds. Be sure to use the same technique throughout this exercise. Record your data in the following table as the first cold trial.

7. Shake out your hand and allow your fingers to rest for a few seconds. Then repeat the 30 second operation with the same hand and same technique. Record your data.

8. Calculate the average of the two cold trials. Record the average in the table.

PART TWO: EFFECT OF SUSTAINED EXERCISE

9. Prediction: Read through the procedure for part two. How do you expect your data to change over time (through all ten trials)? Explain your reasoning.

10. Now using your dominant hand, count the number of times you can open and close a clothespin in 30 seconds. Hold the clothespin between your thumb and index finger and hold your other fingers out straight. Try to do so as many times as you can in 30 seconds. Be sure to open and close the clothespin completely each time. Record your data in the following table as the first dominant hand trial.

11. Repeat the 30 second operation again 9 more times with the same hand and record your data with each successive trial. DO NOT STOP TO REST any longer than it takes to record your data. Again, be sure to use the same technique (fingers) throughout this exercise.

12. Construct a line graph of your results for part two with the vertical axis being labeled “number of contractions” and the horizontal axis being labeled “number of trials”.

13. Answer the questions on your graph paper, using complete sentences.

Data:

|PART ONE | |PART TWO |

|“Off” hand |Number of contractions | |Dominant hand trial # |Number of contractions |

|baseline trial # | | | | |

|1 | | |1 | |

|2 | | |2 | |

|Total: | | |3 | |

|Baseline average: | | |4 | |

| | |5 | |

| | |6 | |

| | |7 | |

|“Off” hand cold trial # | | |8 | |

|1 | | |9 | |

|2 | | |10 | |

|Total: | | | |

|Cold average: | | | |

Questions: Answer question on the back of your graph paper.

1. What effect did the cold temperature have on the action of your hand muscles? Explain why. Was your prediction supported by the data?

2. Describe the shape (no need to explain why) of your line graph in as much detail as possible.

3. Examine your graph. Explain why the number of contractions changed over time (through all ten trials). Was your prediction supported by the data?

4. Did your hand/finger muscles experience a burning sensation during any parts of this lab? Explain why this occurred when it did and why it didn’t occur when it didn’t.

5. Explain why muscles must use lactic acid fermentation instead of cellular respiration during intense physical activity.

................
................

In order to avoid copyright disputes, this page is only a partial summary.

Google Online Preview   Download