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Air resistance modulates horizontal ground reaction forces during treadmill running
Jared R Steele1, Luke VanKeersbilck1, Iain Hunter1
1Department of Exercise Sciences, Brigham Young University, Provo, UT, USA.
Journal of Biomechanics
|October 24, 2025
Summary
Runners adapt to air resistance by adjusting ground reaction forces, increasing propulsion and decreasing braking, especially at faster speeds. This highlights the importance of simulating airflow in treadmill running studies.
Area of Science:
- Biomechanics
- Exercise Physiology
- Sports Science
Background:
- Air resistance significantly impacts running economy and performance, particularly during overground running.
- Understanding how runners adapt to aerodynamic forces is crucial for optimizing training and performance strategies.
- Previous research has not fully elucidated the specific changes in ground reaction forces (GRFs) and spatiotemporal parameters due to airflow during treadmill running.
Purpose of the Study:
- To investigate the effects of simulated air resistance (headwind and tailwind) on GRFs and stride characteristics during constant-speed treadmill running.
- To determine whether runners primarily alter anteroposterior (AP) GRFs or vertical loading and spatiotemporal parameters to counteract air resistance.
- To compare the influence of different airflow conditions (headwind, tailwind, no wind) and running speeds on running biomechanics.
Main Methods:
- Twenty-four trained male runners ran at two speeds (3.35 and 4.46 m/s) on a treadmill under four airflow conditions: headwind (HW), tailwind (TW), no wind (NW), and no fan (NF).
- A custom fan-based system simulated aerodynamic drag comparable to overground running conditions.
- Ground reaction forces (GRFs) and spatiotemporal parameters (contact time, step frequency, stride length) were measured and analyzed.
Main Results:
- Headwind (HW) significantly increased propulsive impulse and reduced braking impulse compared to no fan (NF) at both speeds, with more pronounced effects at the faster speed.
- Tailwind (TW) and no wind (NW) conditions also showed consistent, albeit smaller, differences in propulsive and braking impulses compared to NF.
- Vertical GRFs and spatiotemporal parameters did not differ significantly across airflow conditions, although they scaled with running speed.
Conclusions:
- Trained runners primarily adapt to air resistance by modulating anteroposterior (AP) GRFs, specifically increasing propulsion and reducing braking, rather than altering vertical loading or stride characteristics.
- These biomechanical adjustments are more pronounced at higher running speeds.
- The findings underscore the importance of simulating realistic airflow conditions in laboratory treadmill studies to accurately reflect overground running biomechanics.
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