Muscle Fatigue Investigation Essay Example

  • Category: Biology, Science,
  • Words: 607 Pages: 3
  • Published: 20 August 2020
  • Copied: 198

The aim of the investigation is to measure the effect of break time between activities on the performance of muscles. This will demonstrate muscle fatigue. During the beginning stages of activity, cells use energy from aerobic respiration (utilizing oxygen). Aerobic respiration is carried out in slow twitch muscle fibres. As the activity progresses, oxygen cannot be supplied to the muscles fast enough, thus, anaerobic respiration begins in the fast twitch muscle fibres. Anaerobic respiration does not require oxygen to produce energy, however, it produces lactic acid as a waste product. Lactic acid builds up, causing the sensation of pain or tiredness. 

The muscles also fatigue because anaerobic respiration produces much less ATP than aerobic (two compared to 34). One final reason why muscle fatigue occurs is that the active muscle begins to run out of its store of glucose, and can only get a small amount from the blood. During the recovery stage (a break between activity), oxygen and glucose are restored to the muscles and the lactic acid is expelled within the blood, replenishing the muscle. 

I hypothesis that as break time increases, the time taken to complete the tasks will be shorter. The Independent variable in this invention is the break time provided between tests. Finally, the Dependent variable of the investigation is the time taken to complete the task.

Materials and Method




3) Device to record data (paper and pen or electronic devices)


*Refer to task outline provided below for explanation of trials 

1). Time how long it takes to complete trial 1. Subtract break time from total and record final data.

2). Time how long it takes to complete trial 2. Subtract break time from total and record final data.

3). Time how long it takes to complete trial 3. Subtract break time from total and record final data.

4). Take a 1 minute break and repeat steps 1-3 in reverse order. 

5). Average and record the time for each trial. 

Task Outline:

a) Trial 1. 30 squeezes of peg between thumb and index finger on strong hand, 5 second break, 30 squeezes, 5 second break, 30 squeezes. 

20 second break between trials

b) Trial 2. 30 squeezes of peg between thumb and index finger on strong hand, 10 second break, 30 squeezes, 10 second break, 30 squeezes.

20 second break between trials 

c) Trial 3. 30 squeezes of peg between thumb and index finger on strong hand, 20 second break, 30 squeezes, 20 second break, 30 squeezes

Ethics of experiment:

This experiment had no ethical value and was safe for all participants as well as provided consent.

Improving Validity

Validity is improved by ensuring that the experiment accurately measures what was set out to be achieved. Each trail had a constant set break time. Break time between trials was consistent. The amount of repetitions in each set within the trials was kept the same throughout the investigation. Finally, the person accomplishing the task stayed the same. Overall, by controlling these variables, there was less chance of the dependent variable measured being affected by other factors, making the experiment more valid. 


Seconds Attempt 1 Attempt 2 Attempt 3 Average

Trial 1 13sec 15sec 14sec 14sec

Trial 2 17sec 11sec 12sec 13sec

Trial 3 11sec 11sec 9sec 10sec

Dependent variable-

Time taken to complete task

Independent variable-

Time of rest period/break

Controlled variable-

Amount of squeezes, same hand used each time, same subject doing each trial, temperature of the room 


Factors that impacted reliability/validity of test:

1. Position effect- you will be more fatigued in trial 3, after trial 2, after trial 1.

2. Difficult to keep track of squeezes (count 30 exactly)

3. Poor grip on peg- made some squeezes inconsistent. 

How to improve validity of test:

1. Could have increased time between trials. So the trial before had less of an effect on the trial after.

2. Could have repeated test after a long break with trial reversed and average the times

3. Could have used an easier to grip peg/tool



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