Still air resistance during walking and running

Area of Science:

• Biomechanics
• Human Locomotion
• Aerodynamics

Background:

• Overcoming ground reaction forces during locomotion is well-studied.
• Air resistance (drag) during human movement has been indirectly estimated.
• Direct measurement of air resistance on humans during locomotion was lacking.

Purpose of the Study:

• To directly measure the force of air resistance on human subjects during walking and running.
• To quantify the relationship between air resistance and velocity during terrestrial locomotion.
• To develop a predictive model for air resistance during running.

Main Methods:

• Eight male subjects walked and ran on an instrumented treadmill.
• A flow of laminar air, matching the subject's speed, was directed at the subjects.
• The force exerted by air resistance was directly measured.

Main Results:

• The effective drag coefficient (A_eff) was lower during running compared to walking.
• During running, A_eff decreased with increasing velocity until reaching a plateau.
• Measured A_eff values during running align with predictions from indirect methods.

Conclusions:

• Direct measurement provides a more accurate understanding of air resistance during human locomotion.
• Running generates less air resistance per unit velocity squared than walking.
• A predictive equation for estimating running air resistance based on speed and height is proposed.