Muscle Fatigue Lab - Mrs. Carswell



Muscle Fatigue Lab

Purpose To determine the relationship between stimuli and skeletal muscle fatigue.

Materials Timer, laboratory tubing, textbook, pencil, paper clip, tennis ball

Background Within muscle cells, fatigue is a temporary loss of ability to respond to stimuli. Fatigue occurs when the energy supply to muscle cells has been depleted and waste products have accumulated. During moderate exercise, the blood supplies enough oxygen from inhaled air to provide the muscles with energy (aerobic exercise). Well-conditioned marathon runners pace themselves so that their body’s need for oxygen is equivalent to the amount of air they inhale. Athletes play sports that require intense, anaerobic exertion, such as weightlifters, draw on sources of energy that do not depend on inhaled oxygen. Proper exercise improves aerobic capacity of the cardiovascular system.

Procedure

A. Continual Muscle Stimulation

1. Your partner should have a timer, pencil, and paper to record your data.

2. Hold your arm straight in front of you at a 90° angle (perpendicular to floor).

3. With palm supine, open and close your hand into a fist as many times as possible in 20 seconds.

4. Without resting between trials, repeat this procedure 9 more times.

5. Average all the trials and record the average count.

6. Using the same arm position, squeeze a tennis ball hard in your fist one time every second.

7. Record how many seconds you can continue every second until you stop. This is about how often your heart beats. You are testing to see the difference between cardiac muscle fatigue and skeletal muscle fatigue.

B. Weight Lifting

1. Hold one textbook in each hand. Keep one arm straight by your side and extend the other arm to be perpendicular to the ground. Hold this position as long as you can.

2. Record the time

3. Repeat with other arm.

C. Varying Temperature

1. Write (USE PENCIL) your full name three times in space on data sheet.

2. Tightly hold two ice cubes in your hand for one minute. Drop the ice cubes into the beaker.

3. IMMEDIATELY write your full name three times. DO NOT dry your hand before writing.

4. Warm your hands by rubbing them together.

5. Write your full name three more times.

D. Continual Use

After just 7 seconds of use the muscle begins producing lactic acid as glycogen is broken down to provide energy. To help delay muscle fatigue, the muscle fibers are constantly switching on an off to allow individual fibers a moment to rest. This activity will demonstrate the effects of action of muscle fibers.

1. Hold a popsicle stick in front of you, parallel to the table top.

2. Place a bent paper clip on the stick.

3. Raise the stick until the legs of the paper clip just touch he table.

4. The top of the paper clip should rest on the stick.

5. Hold the stick as steady as you can for about 30 seconds and observe.

6. Grip the stick tighter and repeat step 5.

7. Answer the questions on your answer sheet.

E. Leg Fatigue

If you have time, complete this part of the lab.

Name ______________________________________________________ Date _____________ Per ______

Muscle Fatigue Lab Data Sheet

Part A

|Trial |Part A Count |

|1 | |

|2 | |

|3 | |

|4 | |

|5 | |

|6 | |

|7 | |

|8 | |

|9 | |

|10 | |

|Avg | |

1. How does the feeling in your arm and hand change as you progress through your trials?

2. Do you think your results would have been different if you restricted blood flow to your arm? Explain.

3. How long did your heart survive the fatigue trials? _______________ (time you were able to squeeze tennis ball)

4. How is your heart (cardiac) muscle different from your arm (skeletal) muscle? (just compare how tired your arm got doing the work of the heart)

5. Does cardiac muscle experience fatigue? Does skeletal muscle experience fatigue?

Part B

| |Seconds |

|Left arm | |

|Right arm | |

1. Explain why one arm lasted longer than the other.

2. Are you surprised by your results? Why/Why not?

Part C

|Normal |Ice |Warmed-up |

| | | |

| | | |

| | | |

1. Look at all your signatures. How did the three different temperatures affect your ability to write? Explain why.

Part D

1. What happened to the paper clip even when you kept your hand steady?

2. What caused this?

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

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

Google Online Preview   Download