Tibial Acceleration and Spatiotemporal Mechanics in Distance Runners During Reduced Body Weight Conditions

Document Type

Peer-Reviewed Article

Publication Date

5-2017

Program

Exercise Science

Abstract

Context: Treadmills that unload runners via a differential air pressure bladder (DAP; e.g. AlterG Anti-Gravity Treadmill) are commonly used to reduce effective body weight in a clinical setting, however, the relationship between the level of unloading and tibial stress is currently unknown.

Objective: To determine the relationship between tibial impact acceleration and level of body weight (BW) unloading during running.

Design: Cross-sectional.

Setting: University motion-analysis laboratory.

Participants: 15 distance runners (9M, 6F; 20.4 ± 2.4 years; 60.1 ± 12.6 kg).

Interventions: None.

Main Outcome Measures: Peak tibial acceleration and peak-to-peak tibial acceleration was measured via a uniaxial accelerometer attached to the tibia during a 37-min continuous treadmill run that simulated reduced BW conditions via a DAP bladder. The trial began with a 10-min run at 100% BW followed by nine 3-min stages where BW was systematically reduced from 95% to 60% in 5% increments.

Results: There was no significant relationship between level of BW and either peak tibial acceleration or peak-to-peak tibial acceleration (p>.05). Both heart rate and step rate were significantly reduced with each 5% reduction in BW level (p<.01).

Conclusions: Although ground reaction forces are reduced when running in reduced BW conditions on a DAP treadmill, tibial shock magnitudes are unchanged as an alteration in spatiotemporal running mechanics (e.g. reduced step rate) may nullify the unloading effect.


Comments

epub ahead of print 2016

DOI

10.1123/jsr.2015-0141

PMID

26797694

Publication

Journal of Sport Rehabilitation

Volume

26

Issue

3

Pages

221-226

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