Foot-Strike Impact Measured with a Phone Accelerometer

Using a sensor app (such as phyphox) with the phone secured at the waist in a waist pack, pairs record vertical acceleration while running in different ways. They compare impact peaks to see how technique and surface change the load on the joints.

How to play

1. Explain the app and how to read the acceleration graph; each pair places the phone at the low back with the waist pack snug (4 min).
2. Recording 1: a 20-meter jog with a long stride, landing on the heel in front of the body (4 min).
3. Recording 2: the same jog with a short stride, landing midfoot under the hips; recording 3: same as 2 but on grass or sand if available (6 min).
4. Each pair reads the peak value of each recording and logs it in the class spreadsheet (5 min).
5. Class discussion using the averages: which technique and surface produce the least impact, and when each makes sense (6 min).

Rules

• The waist pack is snug so the phone doesn't bounce or fall out.
• Run at a jog, no sprinting.
• Keep lanes separate and send one pair at a time.
• Anyone without a compatible phone shares their partner's.

Variations

Adaptations

• Wheelchair user: records the chair's vibration over different surfaces and compares them.
• Knee injury: records only walking and analyzes the group's data.
• Autism: has the steps in writing and always works with the same partner.

Learning goals

• Record acceleration data with the phone's sensors.
• Connect running technique to the impact the body absorbs.
• Suggest technique changes to prevent overuse injuries.

Equipment for a class of 25

• tablets or phones: 14
• waist packs: 14
• cones: 8

Teacher tip

Test a few phone models beforehand, since some limit the sampling rate. The peak value depends on the phone and how it's attached, so only compare recordings from the same person.

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