Background: Knee kinematics when running, specifically knee valgus, have been linked to patellofemoral pain syndrome. Assessing running biomechanics requires skill, equipment and time. Clinically, the single leg squat is used to make inferences about knee kinematics during running. No evidence supports this practice. Methods: Sixteen asymptomatic runners and sixteen runners with patellofemoral pain syndrome were recruited. Asymptomatic runners were subdivided by dominant and non-dominant leg and runners with patellofemoral pain syndrome by painful and non-painful leg. This gave four groups. Participants were videoed performing single leg squats and running on a treadmill. Frontal plane knee kinematics were calculated using the frontal plane projection angle. Correlation in frontal plane projection angle between running and single leg squat were calculated using Pearson's correlation coefficient. Differences in frontal plane projection angle between groups for running and single leg squat were calculated using multiple independent t-tests with Bonferroni correction. Findings: Correlation in frontal plane projection angle between running and the single leg squat was not statistically significant for the painful leg group (p = 0.19) but was for the remaining groups (p < 0.05). There was no statistically significant difference in frontal plane projection angle between the four groups when running. Single leg squat frontal plane projection angle was significantly larger for the painful leg group (10.3°) than the dominant leg (−0.2°(p = 0.003)) and non-dominant leg (−0.4°(p = 0.004)) in the asymptomatic runners group. Interpretation: The single leg squat cannot be used to make inferences about frontal plane knee kinematics in running gait in patellofemoral pain syndrome sufferers.

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ObjectiveDifferences in postural control and gait have been identified between people with and without chronic low back pain (CLBP); however, many previous studies present data from small samples, or have used methodologies with questionable reliability. This study, employing robust methodology, hypothesised that there would be a difference in postural control, and spatiotemporal parameters of gait in people with CLBP compared with asymptomatic individuals.MethodsThis cross-sectional case–control study age-matched and gender-matched 16 CLBP and 16 asymptomatic participants. Participants were assessed barefoot (1) standing, over three 40 s trials, under four posture challenging conditions (2) during gait. Primary outcome was postural stability (assessed by root mean squared error of centre of pressure (CoP) displacement (CoPRMSEAP) and mean CoP velocity (CoPVELAP), both in the anteroposterior direction); gait outcomes were hip range of movement and peak moments, walking speed, cadence and stride length, assessed using force plates and a motion analysis system.ResultsThere were no differences between groups in CoPRMSEAP (P=0.26), or CoPVELAP (P=0.60) for any standing condition. During gait, no differences were observed between groups for spatiotemporal parameters, maximum, minimum and total ranges of hip movement, or peak hip flexor or extensor moments in the sagittal plane.ConclusionsIn contrast to previous research, this study suggests that people with mild to moderate CLBP present with similar standing postural control, and parameters of gait to asymptomatic individuals. Treatments directed at influencing postural stability (eg, standing on a wobble board) or specific parameters of gait may be an unnecessary addition to a treatment programme.

BackgroundPeople with chronic low back pain (CLBP) demonstrate greater postural instability compared with asymptomatic individuals. Rocker-sole shoes are inherently unstable and may serve as an effective balance training device. This study hypothesised that wearing rocker-sole shoes would result in long-term improvement in barefoot postural stability in people with CLBP.Methods20 participants with CLBP were randomised to wear rocker-sole or flat-sole shoes for a minimum of 2 hours each day. Participants were assessed barefoot and shod, over three 40 s trials, under 4 posture challenging standing conditions. The primary outcome was postural stability assessed by root mean squared error of centre of pressure (CoP) displacement (CoPRMSE AP) and mean CoP velocity (CoPVELAP), both in the anteroposterior direction, using force plates. Participants' were assessed without knowledge of group allocation at baseline, 6 weeks and 6 months (main outcome point). Analyses were by intention-to-treat.ResultsAt 6 months, data from 11 of 13 (84.6%) of the rocker-sole and 5 of 7 (71.4%) of the flat-sole group were available for analysis. At baseline, there was a mean increase in CoPRMSE AP (6.41 (2.97) mm, p<0.01) and CoPVELAP (4.10 (2.97) mm, p<0.01) in the rocker-sole group when shod compared with barefoot; there was no difference in the flat-sole group. There were no within-group or between-group differences in change in CoP parameters at any time point compared with baseline (1) for any barefoot standing condition (2) when assessed shod eyes-open on firm ground.ConclusionsAlthough wearing rocker-sole shoes results in greater postural instability than flat-sole shoes, long-term use of rocker-sole shoes did not appear to influence postural stability in people with CLBP.