Investigating Muscle Fatigue (AQA A Level Biology): Revision Note

Investigating rate of muscle fatigue

• Repeated contraction of muscles may result in muscle fatigue due to:

  • production of lactate during anaerobic respiration

  • a decrease in the availability of calcium ions after repeated contractions

• It is possible to investigate the effect of repeated contraction on the rate of muscle fatigue

Apparatus

• A hand grip strengthener

• A stopwatch

• Willing human subjects

Method

1. Squeeze the handgrip strengthener to bring the two handles together as many times as they possible over 20 seconds

2. Record the number of successful squeezes

3. Rest for 10 seconds

4. Repeat steps 1-3 several more times

5. Repeat the experiment with other human subjects

Results and analysis

• The results can be plotted on a graph that should show how the number of successful squeezes decreases over time

  • The same hand muscles are being used repeatedly, so we would expect fatigue to reduce the ability of these muscles to contract

Limitations

• This experiment only looks at muscle fatigue in hand muscles

  • Other skeletal muscles may fatigue at different rates

  • Ideally, an experiment would study multiple muscle groups

• The exercise intensity may not be high enough to cause muscle fatigue for some individuals

• The hand grip strengthener may be too difficult to open and close for some individuals, even at the start of the experiment