Foot strike alters ground reaction force and knee load when stepping down during ongoing walking  

Sarah Moudy, Neale Tillin, Siobhan Strike, Amy R. Sibley

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BACKGROUND: When stepping down from a raised surface, either a toe or heel contact strategy is performed. Increased vertical momentum is likely to be experienced during a step descent, yet the extent to which these descent strategies influence the development of load at the ground and knee has not been examined.

RESEARCH QUESTION: Does descent strategy influence ground and knee joint loading? Does the contribution from leading and trailing limb joint mechanics differ between descent strategies?

METHODS: Twenty-two healthy male participants (age: 34.0 ± 6.5 years, height: 179 ± 6.3 cm, mass: 83.5 ± 13 kg) walked along a raised platform, stepped down from a 14 cm height utilising either a toe (n = 10) or heel (n = 12) initial contact, and continued walking. Vertical ground reaction forces and knee external adduction and flexor moments were extracted for the duration of the braking phase. Joint work was calculated for the ankle, knee, and hip in both the leading and trailing limbs.

RESULTS: Waveform analysis of the loading features indicated that a toe-contact strategy resulted in significantly reduced loading rates during early braking (1-32% of the braking phase) and significantly increased magnitude in late braking (55-96% of the braking phase). Individuals performing toe landings completed 33% greater overall work (p = 0.091) in the lead limb and utilised the lead limb ankle joint as the main shock absorber (79% of total lead limb work). Concurrently, the trailing limb performed 29% and 21% less work when lowering the centre of mass and propulsion, respectively, compared to a heel landing.

SIGNIFICANCE: A toe-contact strategy results in reduced limb and knee joint loading rates through greater utilisation of the lead limb ankle joint. A heel-contact strategy, however, can reduce loading during late braking by utilising the functionality of the trailing limb.

© 2019, Elsevier. The attached document (embargoed until 24/12/2020) is an author produced version of a paper published in GAIT & POSTURE uploaded in accordance with the publisher’s self- archiving policy. The final published version (version of record) is available online at the link. Some minor differences between this version and the final published version may remain. We suggest you refer to the final published version should you wish to cite from it.
Original languageEnglish
JournalGait and Posture
Early online date24 Dec 2019
Publication statusPublished - 1 Feb 2020

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