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How does the PowersTM strap influence lower limb muscle activation in individuals with patellofemoral pain?
Gait & Posture xxx (xxxx) xxx–xxx
Contents lists available at ScienceDirect
Gait & Posture journal homepage: www.elsevier.com/locate/gaitpost
How does the PowersTM strap influence lower limb muscle activation in individuals with patellofemoral pain? Henrike Greuel, Lee Herrington, Anmin Liu, Richard K. Jones University of Salford, Salford, Greater Manchester, UK
1. Introduction The quadriceps avoidance strategy has been described as a mechanism that minimises the demand of knee extensor muscles and is commonly observed in individuals with knee injuries such as patellofemoral pain1. Researchers in the USA invented the PowersTM strap that is designed to decrease knee pain and femoral internal rotation in individuals with PFP and has been shown to be successful in modifying lower limb biomechanics2. However, no study investigated the influence of this brace on lower limb muscle activation and the quadriceps avoidance strategy. 2. Research Question How does the PowersTM strap influence lower limb muscle activation of the hamstrings and quadriceps muscles in individuals with PFP?
Table 1 Differences in lower sEMG activity with and without the PowersTM strap. Task
Kinematic variables
Condition
Mean ± SD
p-value
Early stance phase (ESP)
Co-activation ratio
Without strap With strap Without strap With strap Without strap With strap Without strap With strap Without strap With strap Without strap With strap Without strap With strap Without strap With strap Without strap With strap
0.66 ± 0.19 0.7 ± 0.2 122.3 ± 68.9 135.1 ± 93.9 40.4 ± 33.4 34.0 ± 25.8 0.36 ± 0.3 0.39 ± 0.35 77.1 ± 46.8 82.4 ± 55.5 43.2 ± 24.7 41.2 ± 22.2 -0.29 ± 0.46 -0.25 ± 0.54 9.7 ± 14.6 14.7 ± 27.3 15.7 ± 10.0 12.8 ± 8.7
0.25
Mid stance phase (MSP)
Late stance phase (LSP)
4. Results The PowersTM strap condition significantly decreased the hamstrings activity during the early stance phase (ESP) (p=0.05) and late stance phase (LSP) (p=0.05). Furthermore, the pain was significantly reduced with the PowersTM strap (p=0.01) (NPRS: without 4.05 ± 1.96; with 2.18 ± 2.24 the PowersTM strap). (Table 1)
http://dx.doi.org/10.1016/j.gaitpost.2017.06.431
0966-6362/ © 2017 Published by Elsevier B.V.
Net activation knee extensors in % Net activation knee flexors in % Co-activation ratio Net activation knee extensors in % Net activation knee flexors in %
3. Methods 20 individuals with PFP, 11 males and 9 females (age: 29.55 ± 6.44years, height: 1.74 ± 0.09m, mass: 70.08 ± 8.78kg) were recruited. Each individual was asked to run on a 15m walkway at their own selected speed during two conditions: with and without the PowersTM strap, until five successful trials were collected. Muscle activity was collected with surface electromyography (sEMG). Co-activation ratios and the net activity of the quadriceps and the hamstrings muscles were calculated3. The normality was assessed using the ShapiroWilk test and paired sample t-tests were performed at the 95% confidence interval.
Net activation knee extensors in % Net activation knee flexors in % Co-activation ratio
0.34 0.05* 0.36 0.69 0.27 0.54 0.76 0.05*
5. Discussion The PowersTM strap decreased significantly the hamstrings activity during the ESP and LSP. Throughout the stance phase a tendency for an overall increased quadriceps activity and for an overall decreased hamstrings activity could be identified. These results demonstrate that the PowersTM strap has not only the potential to reduce pain, but is also able to modify lower limb muscle activation and might enable the reversal of the quadriceps avoidance strategy in individuals with PFP. References [1] Torry MR, et al. Clin Biomech, 15(3): 147-159. [2] Greuel H, et al. Proceedings of IPFRR, Brisbane, Australia, 2017. [3] T.L. Heiden, et al., Clin Biomech 24 (10) (2009) 833–841.
Contents lists available at ScienceDirect
Gait & Posture journal homepage: www.elsevier.com/locate/gaitpost
How does the PowersTM strap influence lower limb muscle activation in individuals with patellofemoral pain? Henrike Greuel, Lee Herrington, Anmin Liu, Richard K. Jones University of Salford, Salford, Greater Manchester, UK
1. Introduction The quadriceps avoidance strategy has been described as a mechanism that minimises the demand of knee extensor muscles and is commonly observed in individuals with knee injuries such as patellofemoral pain1. Researchers in the USA invented the PowersTM strap that is designed to decrease knee pain and femoral internal rotation in individuals with PFP and has been shown to be successful in modifying lower limb biomechanics2. However, no study investigated the influence of this brace on lower limb muscle activation and the quadriceps avoidance strategy. 2. Research Question How does the PowersTM strap influence lower limb muscle activation of the hamstrings and quadriceps muscles in individuals with PFP?
Table 1 Differences in lower sEMG activity with and without the PowersTM strap. Task
Kinematic variables
Condition
Mean ± SD
p-value
Early stance phase (ESP)
Co-activation ratio
Without strap With strap Without strap With strap Without strap With strap Without strap With strap Without strap With strap Without strap With strap Without strap With strap Without strap With strap Without strap With strap
0.66 ± 0.19 0.7 ± 0.2 122.3 ± 68.9 135.1 ± 93.9 40.4 ± 33.4 34.0 ± 25.8 0.36 ± 0.3 0.39 ± 0.35 77.1 ± 46.8 82.4 ± 55.5 43.2 ± 24.7 41.2 ± 22.2 -0.29 ± 0.46 -0.25 ± 0.54 9.7 ± 14.6 14.7 ± 27.3 15.7 ± 10.0 12.8 ± 8.7
0.25
Mid stance phase (MSP)
Late stance phase (LSP)
4. Results The PowersTM strap condition significantly decreased the hamstrings activity during the early stance phase (ESP) (p=0.05) and late stance phase (LSP) (p=0.05). Furthermore, the pain was significantly reduced with the PowersTM strap (p=0.01) (NPRS: without 4.05 ± 1.96; with 2.18 ± 2.24 the PowersTM strap). (Table 1)
http://dx.doi.org/10.1016/j.gaitpost.2017.06.431
0966-6362/ © 2017 Published by Elsevier B.V.
Net activation knee extensors in % Net activation knee flexors in % Co-activation ratio Net activation knee extensors in % Net activation knee flexors in %
3. Methods 20 individuals with PFP, 11 males and 9 females (age: 29.55 ± 6.44years, height: 1.74 ± 0.09m, mass: 70.08 ± 8.78kg) were recruited. Each individual was asked to run on a 15m walkway at their own selected speed during two conditions: with and without the PowersTM strap, until five successful trials were collected. Muscle activity was collected with surface electromyography (sEMG). Co-activation ratios and the net activity of the quadriceps and the hamstrings muscles were calculated3. The normality was assessed using the ShapiroWilk test and paired sample t-tests were performed at the 95% confidence interval.
Net activation knee extensors in % Net activation knee flexors in % Co-activation ratio
0.34 0.05* 0.36 0.69 0.27 0.54 0.76 0.05*
5. Discussion The PowersTM strap decreased significantly the hamstrings activity during the ESP and LSP. Throughout the stance phase a tendency for an overall increased quadriceps activity and for an overall decreased hamstrings activity could be identified. These results demonstrate that the PowersTM strap has not only the potential to reduce pain, but is also able to modify lower limb muscle activation and might enable the reversal of the quadriceps avoidance strategy in individuals with PFP. References [1] Torry MR, et al. Clin Biomech, 15(3): 147-159. [2] Greuel H, et al. Proceedings of IPFRR, Brisbane, Australia, 2017. [3] T.L. Heiden, et al., Clin Biomech 24 (10) (2009) 833–841.