Investigating Muscle Fatigue

Lydia Guo (Period 1)

Hypotheses

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Claim

The dominant hand has a higher average rate of opening and shutting the binder clip and overall higher free energy compared to that of the non-dominant hand.

Evidence

The data collected appears to support the prediction and alternative hypotheses. When the dominant hand was using the binder clip, the number of repetitions was consistently higher in the personal data, and it was generally higher in the class data. When looking at the average of repetitions, my personal data showed that the dominant hand had an average of 26.6 repetitions, whereas the non-dominant hand had an average of 22.6 repetitions, which is a difference of 4. The class data showed that the dominant hand had an average of 36.4 repetitions, and the non-dominant hand had an average of 27.8 repetitions, which is a difference of 8.6.

Reasoning

The number of repetitions for each subsequent trial decreased continuously because of the limits of cellular respiration. The first trial had the most amount of times opening and shutting the binder clip because oxygen intake was able to keep up with the processes of aerobic respiration, which creates the optimum maximum amount of ATP (36-68) that will provide the energy for muscle contraction. Since the trials were done without any period of time for resting in between, the continuous exercise became too strenuous, and oxygen intake decreased as temperature (heat) increased in the fingers' muscles. Thus without enough oxygen, cells turned to anaerobic respiration (fermentation) to recycle NAD+ in glycolysis to continue producing ATP for muscle contraction. However, anaerobic respiration is much less efficient in comparison to aerobic respiration as it creates only 2 ATP per glucose molecule. With less ATP and decreasing amounts of free energy, muscle contraction slows and thus reduces the number of repetitions for each trial. The dominant hand generally had a larger average of repetitions per trial, because the dominant hand has more/stronger muscle than the non-dominant hand. This occurs because an individual will use his or her dominant hand much more in day-to-day activities compared to the non-dominant hand. Thus this results in the dominant hand being capable of opening and shutting the binder clip at a faster rate (number of repetitions over the same trial time period).

Quantitative Data

Personal Data for Number of Times Opening/Shutting a Binder Clip
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Class Average Data for Number of Times Opening/Shutting a Binder Clip
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Qualitative Data

  • Sweaty fingers/higher temperature of skin
  • Red fingers
  • Soreness and/or pain in muscles

Graph

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Reflection

  1. I learned that continuous and strenuous exercise will increase muscle fatigue. Weaker muscles will become tired at a faster rate compared to stronger muscles.
  2. This activity helped me understand what circumstances may cause a cell to turn from aerobic respiration to anaerobic respiration (lactic acid fermentation in this case). It reminded me that ATP was used for muscle contraction, and that oxygen intake decreased when temperature increased. Free energy also decreases when heat increases.