Backward walking alters vastus medialis oblique/vastus lateralis muscle activity ratio in females with patellofemoral pain syndrome.
Level 4 - case-series / case-control
Case-control observational physiological study
PubMed 31453558 · doi:10.5606/tftrd.2019.2445
What was done
Researchers evaluated the effect of backward walking versus forward walking on vastus medialis oblique (VMO) and vastus lateralis (VL) muscle activation in 40 female participants (mean age 20.9 ± 1.9 years). Participants were divided into a unilateral patellofemoral pain syndrome (PFPS) group (n = 20) and a healthy control group (n = 20). Surface electromyography (EMG) of the VMO and VL was recorded while participants walked forward and backward at 3 km/h using the Myomonitor IV EMG system.
What was found
Both groups showed a significant increase in VMO and VL EMG activities during backward walking compared to forward walking (p = 0.001). During backward walking, the PFPS group had significantly higher VMO activity than healthy controls (p = 0.013), with no significant difference in VL activity (p = 0.916). During forward walking, there was no significant difference between groups for VMO (p = 0.348) or VL (p = 0.705). The VMO/VL ratio in the PFPS group was significantly higher during backward walking than forward walking (p = 0.001), whereas healthy controls showed no difference between walking directions (p = 0.841). During backward walking, the ratio in the PFPS group was significantly higher than in healthy controls (p = 0.016), with no between-group difference during forward walking (p = 0.100). Exact mean values and standard deviations for EMG amplitudes and ratios were not reported in the abstract.
Why it matters
Backward walking preferentially increases VMO activation and normalizes the VMO/VL activation ratio in women with PFPS, providing a biomechanical rationale for incorporating backward walking into rehabilitation programs.
Limits
The study only measured acute, single-session EMG responses and did not evaluate clinical outcomes such as pain reduction, functional recovery, or long-term training adaptations. The sample is small (n = 40) and limited exclusively to young adult females with unilateral symptoms, limiting generalizability to males, older individuals, or bilateral presentations. Absolute numerical values and effect sizes for EMG data were omitted from the abstract.
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