Running Velocity Does Not Influence Lower Limb Mechanical Asymmetry

Abstract

We examined the effect of running velocity upon magnitude and range of asymmetry in the main kinetics and kinematics of treadmill running at constant, submaximal velocities. Nine well-trained, uninjured distance runners ran, in a random order, at seven running velocities (10, 12.5, 15, 17.5, 20, 22.5, and 25 km.h −1) for 60 s (separated by > 90 s of rest) on an instrumented treadmill (ADAL3D-WR, Medical Development, France). Continuous measurement (1,000 Hz) of spatio-temporal, horizontal force production, and spring-mass characteristics was performed and data over 10 consecutive steps (5 right and 5 leg foot contacts after ∼50 s of running) were used for subsequent comparisons. Group mean and the range of asymmetry scores were assessed from the "symmetry angle" (SA) formulae where a score of 0%/100% indicates perfect symmetry/asymmetry. Mean SA scores for spatio-temporal variables were lower than 2%: contact time (0.6 ± 0.1%; range: 0.4-0.7%), aerial time (1.7 ± 0.2%; range: 1.3-2.1%) as well as step length and step frequency (0.7 ± 0.2%; range: 0.5-0.9%). Mean loading rate (5.3 ± 1.1%; range: 4.1-6.9%) and spring mass model [peak vertical force: 3.2 ± 1.6% (range: 2.9-3.4%); maximal downward vertical displacement: 11.2 ± 6.0% (range: 9.2-14.0%); leg compression: 3.6 ± 1.9% (range: 2.9-5.6%); vertical stiffness: 8.8 ± 1.9% (range: 7.1-11.6%); leg stiffness: 1.6 ± 0.6% (range: 1.2-2.9%)] presented larger mean SA values. Mean SA scores ranged 1-4% for duration of braking (1.3 ± 0.3%; range: 0.9-2.0%) and push-off (1.6 ± 0.9%; range: 1.2-2.4%) phases, peak braking (2.4 ± 1.1%; range: 1.6-3.6%), and push-off (1.7 ± 0.9%; range: 1.2-2.2%) forces as well as braking (3.7 ± 2.0%; range: 2.8-5.8%) and push-off (2.1 ± 0.8%; range: 1.3-2.6%) impulses. However, with the exception of braking impulse (P = 0.005), there was no influence of running velocity on asymmetry scores for any of the mechanical variables studied (0.118<P<0.920). Modifying treadmill belt velocity between 10 and 25 km.h −1 induced large adjustments in most running kinetics and kinematics. However, there was no noticeable difference in group mean and the range of asymmetry values across running velocities, with the magnitude of these scores being largely dependent on the biomechanical variable of interest. Finally, the relatively large range of asymmetry between participants for some variables reinforces the importance of assessing asymmetry on an individual basis.

Increases in speed do not change gait symmetry or variability in world-class race walkers

“…This demonstrates that these athletes maintained their magnitude of symmetry (or asymmetry) in these variables despite changes in kinetic and spatiotemporal variables in response to increasing speed (Figure 2). This is in line with similar research on symmetry in sprinting where no changes were evident with increasing speed (Girard et al, 2019). The results from the study of Girard et al (2019) and our study on race walking indicate that the movement variability and symmetry present are unique to the individual's motor system.…”

“…This is in line with similar research on symmetry in sprinting where no changes were evident with increasing speed (Girard et al, 2019). The results from the study of Girard et al (2019) and our study on race walking indicate that the movement variability and symmetry present are unique to the individual's motor system. These findings suggest that practitioners should not be concerned that increasing speed in either running (Girard et al, 2019) or race walking heightens the risk of injury through increasing their client's asymmetry; however, athletes recovering from injury might show increased asymmetry (Thomson et al, 2018), but this should be differentiated from the effects of increased speed alone.…”

“…Increased gait asymmetry has been associated with injury (Impellizzeri, Rampinini, Maffiuletti, & Marcora, 2007) or decreased performance (Bell, Sanfilippo, Binkley, & Heiderscheit, 2014), and indeed some race walk coaches believe that symmetry is needed for adopting a legal and efficient technique (Salvage & Seaman, 2011). Increased asymmetry in the vertical GRF pattern has been reported with increased running speed in participants returning to sport after anterior cruciate ligament reconstruction (Thomson, Einarsson, Hansen, Bleakley, & Whiteley, 2018), whereas a study on healthy competitive sprinters at a range of speeds found no change in asymmetry across the analysed speeds (Girard, Morin, Ryu, Read & Townsend, 2019). It has been established that symmetry did not change with distance walked in a sample of elite race walkers, nor were there large differences between senior and junior race walkers (Tucker & Hanley, 2017), but these tests were conducted at a constant pace, which is unusual in race walking competitions (Hettinga et al, 2019).…”

“…The aim of this study was to analyse the extent of any changes in gait variability and symmetry in world-class race walkers across a range of speeds. Based on previous research (Girard et al, 2019;Hanley & Tucker, 2018), it was hypothesised that variability and symmetry scores would not change with increases in speed.…”

Running mechanics adjustments to perceptually-regulated interval runs in hypoxia and normoxia

“…It is well described that the mechanical behaviour is substantially influenced by running velocity variations. 18 This implies that, during self-paced runs, it is difficult (if not impossible) to distinguish the effects of fatigue from auto-regulatory mechanisms associated with a pacing strategy on stride mechanics parameters. To overcome this limitation, despite being free to vary during the proposed HIIE, the running velocity was externally imposed for 30 s both at the onset and end of each 4-min interval for the purpose of assessing acute changes in stride mechanics.…”