Muscle Fatigue

Materials: ★☆☆ Easy to get from supermarket or hardware store
Difficulty: ★☆☆ Can be easily done by most teenagers
Safety: ★☆☆ Minimal safety procedures required

Categories: Body Systems, Respiration and Photosynthesis, Sports Science

Alternative titles: Finger Marathon

Summary

Students rapidly open and close a spring clothes peg in three 30-second bouts to observe muscle fatigue and recovery. Results are graphed to link falling repetitions with the switch from aerobic to anaerobic respiration and lactic acid buildup.

Procedure

  1. Gather materials per pair: 1 spring clothes peg (same type for all pairs), stopwatch or timer, data sheet, pencil, and optional alcohol wipes for shared pegs.
  2. Standardize the setup: use the same peg model and spring strength for all students; hold the peg between thumb and forefinger of the writing hand unless testing hand differences.
  3. Practice for 5–10 s to learn the full open–close motion. The peg must open fully each count; partial opens do not count.
  4. Assign roles: Performer (squeezes and counts aloud) and Timekeeper (calls time marks and records counts). You will swap roles after the first run.
  5. Run 1 (writing hand): on “go,” perform as many full opens as possible in 30 s. Timekeeper records the total for 0–30 s.
  6. Rest exactly 15–30 s (use the same rest for everyone).
  7. Continue immediately for the next two intervals without resetting the count aloud. Timekeeper records the additional opens achieved during 30–60 s, then during 60–90 s (counts per interval, not cumulative).
  8. Swap roles and repeat Run 1 with the partner following the same timing and rest.
  9. Optional Run 2 (non-writing hand): repeat the three 30 s intervals to compare hands.
  10. Graph results for each person: x-axis = interval (0–30 s, 30–60 s, 60–90 s); y-axis = opens per 30 s interval. Plot both partners on the same axes for comparison.
  11. Analyze briefly: note where performance drops, describe sensations (burning, slowing), and connect to energy use (aerobic early, increasing anaerobic contribution later). Record one or two sentences interpreting the pattern.

📄 ACTIVITY: Finger marathon - Science Learning Hub: https://www.sciencelearn.org.nz/resources/1926-finger-marathon

Variations

Safety Precautions

Questions to Consider