1Department of Mechanical & Materials Engineering, Queen's University, Kingston, ON, Canada 2Human Mobility Research Centre, Queen's University, Kingston, ON, Canada 3Department of Kinesiology & Nutrition, University of Illinois, Chicago, IL, USA.
Peak knee joint contact forces ("loads") in running are much higher than they are in walking, where the peak load has been associated with the initiation and progression of knee osteoarthritis. However, runners do not have an especially high risk of osteoarthritis compared to non-runners. This paradox suggests that running somehow blunts the effect of very high peak joint contact forces, perhaps to provide a load per unit distance traveled (PUD) that is relatively low.
To compare peak and PUD knee joint loads between human walking and running.
Fourteen healthy adults walked and ran at self-selected speeds. Ground reaction force and motion capture data were measured and combined with inverse dynamics and musculoskeletal modeling to estimate the peak knee joint loads, PUD knee joint loads, and the impulse of the knee joint contact force for each gait with a matched-pair (within-subject) design.
The peak load was three times higher in running (8.02 vs. 2.72 bodyweights, p < 0.001) but the PUD load did not differ between running and walking (0.80 vs. 0.75 bodyweights·m, p = 0.098). The impulse of the joint contact force was greater for running than for walking (1.30 vs. 1.04 bodyweights·s, p < 0.001). The peak load increased with increasing running speed, while the PUD load decreased with increasing speed.
Compared to walking, the relatively short duration of ground contact and relatively long length of strides in running seem to blunt the effect of high peak joint loads, such that the PUD loads are no higher than in walking. Waveform features other than or in addition to the peak value should be considered when studying joint loading and injuries.
[Show abstract][Hide abstract] ABSTRACT: We sought to determine if an in-field gait retraining program can reduce excessive impact forces and peak hip adduction without adverse changes in knee joint work during running. Thirty healthy at-risk runners who exhibited high-impact forces were randomized to retraining [21.1 (±1.9) years, 22.1 (±10.8) km/week] or control groups [21.0 (±1.3) years, 23.2 (±8.7) km/week]. Retrainers were cued, via a wireless accelerometer, to increase preferred step rate by 7.5% during eight training sessions performed in-field. Adherence with the prescribed step rate was assessed via mobile monitoring. Three-dimensional gait analysis was performed at baseline, after retraining, and at 1-month post-retraining. Retrainers increased step rate by 8.6% (P < 0.0001), reducing instantaneous vertical load rate (−17.9%, P = 0.003), average vertical load rate (−18.9%, P < 0.0001), peak hip adduction (2.9° ± 4.2 reduction, P = 0.005), eccentric knee joint work per stance phase (−26.9%, P < 0.0001), and per kilometer of running (−21.1%, P < 0.0001). Alterations in gait were maintained at 30 days. In the absence of any feedback, controls maintained their baseline gait parameters. The majority of retrainers were adherent with the prescribed step rate during in-field runs. Thus, in-field gait retraining, cueing a modest increase in step rate, was effective at reducing impact forces, peak hip adduction and eccentric knee joint work.
Scandinavian Journal of Medicine and Science in Sports 03/2015; DOI:10.1111/sms.12413 · 2.90 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: We investigated the association between objectively measured daily walking and knee structural change, defined either as radiographic worsening or as cartilage loss, in people at risk of or with knee osteoarthritis (OA).
Participants from the Multicenter Osteoarthritis Study (MOST) with Kellgren-Lawrence grades 0-2 and daily walking (measured with the StepWatch) at the 60-month visit were included. Participants had fixed-flexion, weight-bearing radiographs and knee magnetic resonance images (MRI) at 60 and 84 months. Radiographic worsening was read in both knees using the Osteoarthritis Research Society International grading, and MRI were read for 1 knee using the Whole-Organ MRI Score semiquantitative scoring. OR and 95% CI were calculated comparing those in the middle tertile against the lowest and highest tertiles of daily walking using logistic regression models and generalized estimating equations. Data on walking with moderate to vigorous intensity (min with > 100 steps/min/day) were associated to structural change using multivariate and logistic regression models.
The 1179 study participants (59% women) were 67.0 years old (± 7.6), with a mean (± SD) body mass index of 29.8 kg/m(2) (± 5.3) who walked 6981 (± 2630) steps/day. After adjusting for confounders, we found no significant associations between daily walking and radiographic worsening or cartilage loss. More time spent walking at a moderate to vigorous intensity was not associated with either radiographic worsening or cartilage loss.
Results from the MOST study indicated no association between daily walking and structural changes over 2 years in the knees of people at risk of or with mild knee OA.
The Journal of Rheumatology 06/2015; 42(9). DOI:10.3899/jrheum.150071 · 3.19 Impact Factor
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