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Control Entropy (CE) Identifies Constraints of Treadmill Locomotion in Highly Trained Runners
Author(s) -
McGregor Stephen James,
Busa Michael A,
Yaggie James A,
Skufca Joseph D,
Bollt Erik M
Publication year - 2009
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.23.1_supplement.818.13
Subject(s) - treadmill , mathematics , physics , simulation , computer science , physical therapy , medicine
The purpose of this study was to test if Control Entropy (CE), a novel regularity measure not limited by the requirement of stationarity, could identify differential changes in system constraints of locomotion in highly trained runners using high resolution accelerometry (HRA). Procedures were approved by the local HSRC. Collegiate runners (n=8, 21.4±1.7yr, 65.5±5.7 kg, 70.1±6.2 ml/kg/min) performed two level treadmill tests starting at 2 kph and increasing 2 kph/2 min to exhaustion. Gaits ranged from slow walking to maximal running. Data was streamed at 625 Hz from wireless triaxial HRA (Microstrain, VT) affixed to subject's lower back. CE (CEKS[x(t)] =hKS[sign(dx/dt(t))] was calculated using 8 bit partitions and multi‐scale window lengths and compared using K‐L analysis. Dominant CE modes in K‐L analysis showed that CE initially increased in all axes during the walk phase, then declined during running first in the vertical (V), then lateral (M/L) and anterior/posterior (A/P) axes (p<.05). These results indicate that constraints in locomotion are apparent earliest in the V, and latest in the A/P axes. Accelerations increased most dramatically in the V axis during running to overcome gravity (energetic constraint), while constraints in the A/P axis are most likely due to biomechanical limitations. Therefore, CE may indeed identify differential constraints during treadmill locomotion.