Relationship between shock attenuation and stride length during running at different velocities

Abstract

The purpose of the study was to investigate the characteristics of shock attenuation during high-speed running. Maximal running speed was identified for each subject [n = 8 males, 25 (SD 4.6) years; 80 (8.9) kg; 1.79 (0.06) m] as the highest speed that could be sustained for about 20 s on a treadmill. During testing, light-weight accelerometers were securely mounted to the surface of the distal antero-medial aspect of the leg and frontal aspect of the forehead. Subjects completed running conditions of 50, 60, 70, 80, 90, and 100% of their maximal speeds with each condition lasting about 20 s. Stride length, stride frequency, leg and head peak impact acceleration were recorded from the acceleration profiles. Shock attenuation was analyzed by extracting specific sections of the acceleration profiles and calculating the ratio of head to leg power spectral densities across the 10-20 Hz frequency range. Both stride length and stride frequency increased across speeds (P < 0.05) and were correlated with running speed (stride length r = 0.92, stride frequency r = 0.89). Shock attenuation increased about 20% per m x s(-1) across speeds (P< 0.05), which was similar to the 17% increase in stride length per m x s(-1). Additionally, shock attenuation was correlated with stride length (r = 0.71) but only moderately correlated with stride frequency (r = 0.40) across speeds. It was concluded that shock attenuation increased linearly with running speed and running kinematic changes were characterized primarily by stride length changes. Furthermore, the change in shock attenuation was due to increased leg not head peak impact acceleration across running speeds.

Muscular strategy shift in human running: dependence of running speed on hip and ankle muscle performance

“…Second-order polynomial trends have also been used to describe the relationship between stride frequency and running speed (Mercer et al, 2002). Taken together, these results suggest a causal link between the actions of the hip muscles and stride frequency.…”

“…Runners appear to use two different strategies to increase their speed. Up to ~7ms -1 , running speed is increased by exerting larger support forces during ground contact, which has been shown to correlate with increases in stride length (Derrick et al, 1998;Frederick, 1986;Mercer et al, 2005;Mercer et al, 2002;Weyand et al, 2000). Using a simple point-mass model of running, it is relatively straightforward to show that a larger support force produces a larger stride length because the body spends more time in the air (see Appendix).…”

Acute effect of different minimalist shoes on foot strike pattern and kinematics in rearfoot strikers during running

“…The runners analysed by those authors progressively adopted shorter stride lengths and higher stride frequencies when running condition changes from cushioned to minimalist and from minimalist to barefoot. Reduced stride length has been shown to decrease impact characteristics and to increase shock attenuation (Derrick, Hamill, & Caldwell, 1998;Mercer, Vance, Hreljac, & Hamill, 2002). Therefore, once again, the attempt to reduce the possible pain caused by the heel-ground contact, while barefoot or in minimalist footwear would suggest these alterations.…”

Method analysis of accelerometers and gyroscopes in running gait: A systematic review

“…Mercer et al 34 reported that when the subject was standing the axis of the accelerometer was aligned with the longitudinal axis of the tibia however with any manipulation of stride length, as can happen in fatiguing long distance running, the axis alignment became distorted. Although previous research has stated that this misalignment leads to minimal differences in acceleration Abt et al 1 Bergamini et al 17 Butler et al 24 Channells et al 12 Clansey et al 25 Clansey and Hanlon 26 Clark et al 27 Crowell et al 28 Derrick et al 29 Gullstrand et al 10 Laughton et al 30 Le Bris et al 31 Lee et al 32 Lee et al 5 McGregor et al 33 Mercer et al 34 Mercer et al 35 Mercer et al 36 Milner et al 37 Patterson et al 38 Stohrmann et al 22 Stohrmann et al 23 Tan et al 14 power spectral density (PSD) using a previously published method 44 . Using the aforementioned methods tibial acceleration has been successfully identified to be reduced in high arched runners when running in cushion trainers shoes compared to motion control shoes 24 and also decrease when provided as visual feedback to those running on treadmills 28 .…”