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A comparison of augmented low-Dye taping and ankle bracing on lower limb muscle activity during walking in adults with flat-arched foot posture
Available online at www.sciencedirect.com
Journal of Science and Medicine in Sport 15 (2012) 8–13
Original research
A comparison of augmented low-Dye taping and ankle bracing on lower limb muscle activity during walking in adults with flat-arched foot posture Melinda M. Franettovich a,∗ , George S. Murley b,c , Bianca S. David b , Adam R. Bird b,c a
School of Physiotherapy, Australian Catholic University, Australia b Department of Podiatry, La Trobe University, Australia c Musculoskeletal Research Centre, La Trobe University, Australia
Received 8 October 2010; received in revised form 26 April 2011; accepted 20 May 2011
Abstract Objective: To compare the effect of taping and bracing on lower limb muscle activity during gait. Design: Cross-sectional laboratory study. Methods: Twenty-seven asymptomatic adults with flat-arched foot posture were recruited to this study. They walked over-ground under three randomly allocated conditions: (i) barefoot; (ii) augmented low-Dye taping; (iii) replaceable ankle brace. Electromyographic (EMG) activity from tibialis posterior, tibialis anterior, peroneus longus and medial gastrocnemius was measured for each condition. Peak EMG amplitude and time of peak EMG amplitude were assessed from stance phase data. A series of one-way repeated measure analysis of variance followed by Bonferroni post hoc tests were undertaken (α = 0.05). Results: Tibialis posterior peak EMG amplitude decreased by 22% and 33% with bracing and taping (respectively), compared to barefoot. Peak amplitude was also decreased for peroneus longus by 34% and 30% and for tibialis anterior by 19% and 13% with bracing and taping (respectively), compared to barefoot. Small significant changes in time of peak EMG amplitude were found for tibialis posterior and tibialis anterior with taping and bracing compared to barefoot. The effect of taping and bracing was only different for tibialis posterior peak EMG amplitude, with tape producing a 15% reduction compared to bracing. Conclusion: The augmented low-Dye tape and replaceable ankle brace used in this study could be useful in managing overuse and dysfunction of selected leg muscles, particularly tibialis posterior, by reducing their level of activation during walking. © 2011 Sports Medicine Australia. Published by Elsevier Ltd. All rights reserved. Keywords: Athletic tape; Braces; Electromyography; Gait; Ankle
1. Introduction External ankle support, in the form of taping and bracing, has long been used to assist with management of various lower limb conditions. A key distinction between taping and bracing modalities is that tape is adhered to the skin, whereas bracing is usually held in place by laces or Velcro®TM straps. Over time, taping and bracing have evolved to include features that reduce foot pronation. Anti-pronation taping has demonstrated efficacy in reducing pain in individuals with heel pain,1,2 plantar fasciitis,3 and there is preliminary evidence from case reports for its use in Achilles tendinopathy,4 iliotibial band friction syndrome,5 anterior knee pain,5 and ∗
Corresponding author. E-mail address: [email protected] (M.M. Franettovich).
medial tibial stress syndrome.5 With this in mind, several laboratory-based studies have investigated the biomechanical and neuromuscular effects of this modality, primarily to develop understanding of underlying mechanisms linking anti-pronation taping with positive clinical outcomes. An anti-pronation taping technique, termed the augmented low-Dye, has been reported to reduce activity of tibialis anterior, tibialis posterior and medial gastrocnemius in individuals with varied foot types, as well as those with and without musculoskeletal pain.6,7 Despite the clinical use of ankle bracing in the management of lower limb conditions, it remains unclear what effect anti-pronation bracing has on individuals with existing injuries. Given the neuromuscular effects of anti-pronation taping described above, this modality may counteract altered muscular activity associated in those with specific musculoskeletal disorders as well as with
1440-2440/$ – see front matter © 2011 Sports Medicine Australia. Published by Elsevier Ltd. All rights reserved. doi:10.1016/j.jsams.2011.05.009
M.M. Franettovich et al. / Journal of Science and Medicine in Sport 15 (2012) 8–13
altered foot posture. Firstly, there is preliminary evidence that altered neuromuscular control of the leg is associated with musculoskeletal disorders, such as tibialis posterior tendon dysfunction.8 Ringleb et al.8 investigated muscle activation in four females with stage II posterior tibial tendon dysfunction and reported that these individuals exhibited increased activity of tibialis posterior, tibialis anterior, peroneus longus and medial gastrocnemius during walking, compared to healthy controls. The authors hypothesised that the increase in muscle activity may be associated with the development of a valgus foot deformity (i.e. flattening of the medial arch), although conclusions from this study are limited due to the small sample size. Secondly, previous studies have reported increased activity of some leg muscles (tibialis posterior, tibialis anterior, toe flexors, calf) in individuals who exhibit excessive pronation.9–12 With the growing body of evidence that foot posture and musculoskeletal injuries systematically alter muscle activity during gait, there is a need to develop interventions that optimise muscle activity. To our knowledge, no published research has investigated the effect of anti-pronation bracing on tibialis posterior, one of the primary muscles that counteracts foot pronation during normal gait. It is of interest to clinicians to investigate and compare the effect of antipronation taping and bracing on lower limb muscle activity during gait as this may provide further information when deciding which modality is the best choice for treatment of lower limb overuse injuries. For example, taping can be problematic for some individuals such as those with allergic reactions to tape and those with vulnerable skin (e.g. elderly, presence of skin conditions such as psoriasis or eczema). For these individuals, bracing may be a more suitable treatment when support is needed for extended periods of time. Other comparisons between taping and bracing worth consideration relate to the skill and training required for application (whether an individual can apply independently at home) and the cost of the intervention (taping may be more cost effective in the short term, but bracing may be a more cost effective alternative for longer periods of time). Therefore, the aim of this study was to investigate whether anti-pronation taping and bracing has an effect on muscle activity of the lower leg when compared to barefoot walking in individuals with flat-arched foot posture. It was hypothesised that both the tape and brace would reduce the requirement of the muscular system (by providing external support) and therefore reduce the activity of lower leg muscles, particularly tibialis posterior, during gait.
2. Methods Twenty-seven adults with flat-arched feet (13 males and 14 females) aged 18–37 years were recruited to this study (Supplementary File 1). The participants were without symptoms of macrovascular (e.g. angina, stroke, peripheral vascular disease) and/or neuromuscular disease, or any
9
biomechanical abnormalities that affected their ability to walk. Ethical approval was obtained for the study from the La Trobe University Human Ethics Committee (Ethics ID: FHEC06/205) and it was registered with the Radiation Safety Committee of the Victorian Department of Human Services. A foot screening protocol was used to include only participants with flat-arched foot posture – those most likely to benefit from anti-pronation taping or bracing. The foot screening protocol included both clinical and radiographic measures of foot posture.13 This protocol was derived from normative foot posture values for two clinical measurements (the arch index and normalised navicular height to truncated foot length) and four angular measurements obtained from antero-posterior and lateral X-rays (talus-second metatarsal angle, talonavicular coverage angle, calcaneal inclination angle and calcaneal-first metatarsal angle). To qualify for the flat-arched group, participants had to exhibit an arch index or normalised navicular height to truncated foot length measurement greater than two standard deviations from mean values obtained for people with normal-arched feet.13 Furthermore, their radiographic measurements had to be greater than one standard deviation from the mean values obtained for people with normal-arched feet for either the sagittal and or transverse plane measurements (Supplementary File 1).13 The X-rays were performed in accordance with the Australian Radiation Protection and Nuclear Safety Agency Code of Practice for the Exposure of Humans to Ionizing Radiation for Research Purposes (2005). Two types of anti-pronation external ankle support were investigated: (i) augmented low-Dye tape (ALD) and (ii) a commercially available prefabricated semi-rigid ankle brace (Push® Aequi, NEA International, Netherlands). ALD tape has been used in several gait studies.6,7,14,15 It features the low-Dye technique (spurs and mini-stirrups) with the addition of three reverse sixes and two calcaneal slings anchored to the lower third of the leg. The tape is applied with the talocrural joint in plantigrade and the rearfoot in approximately two-thirds of the total available range of motion of supination. A rigid sports tape (38 mm zinc oxide adhesive, Leukosport BDF) was used (Fig. 1). The brace featured a plastic semi-rigid medial ankle support, one diagonal band with Velcro® over the antero-lateral aspect of the ankle, and two adjustable elastic straps with Velcro® that wrapped from the medial and lateral aspects of the rearfoot (Fig. 1). Participants attended a single testing session in the EMG gait laboratory. Bipolar fine-wire intramuscular electrodes were used to record the EMG signal from tibialis posterior and peroneus longus. The electrodes were fabricated from 75 m Teflon® coated stainless steel wire (A-M Systems, Washington, USA) with 1 mm of insulation stripped to form the recording surface of the two wires. The electrode wires were inserted into a 23 gauge sterilized single use hypodermic needle with the exposed electrode tips bent 3 mm and 5 mm to prevent the contact areas from touching during recording. For tibialis posterior, the intramuscular electrode was inserted at a distance of approximately 50% between the popliteus
10
M.M. Franettovich et al. / Journal of Science and Medicine in Sport 15 (2012) 8–13
at approximately 25% of the distance from the medial side of the popliteus cavity to the calcaneal tubercle.19 The temporal characteristics of the walking cycle were measured using circular force sensitive resistors (footswitches) with a diameter of 13 mm (Model: 402, Interlink Electronics, California, USA). These were placed on the plantar surface of the interphalangeal joint of the hallux and the most posterior plantar aspect of the calcaneus to record the timing of heel contact, toe contact, heel off and toe off. During testing, participants first walked barefoot and then under two randomly allocated conditions: (i) barefoot with ALD taping; or (ii) barefoot with a replaceable ankle brace (Figs. 1 and 2). Participants walked continuously for three minutes with the brace and tape just prior to recording, to ensure the participant was comfortable and to reduce any cross-over effect from the respective condition (Fig. 2). They were instructed to walk at their self-selected walking speed, which was established following a warm-up period from two
Fig. 1. The ankle brace (top) and augmented low-Dye (ALD) taping method (bottom) are shown.
cavity to the medial malleolus.16 Peroneus longus – the intramuscular electrode was inserted at approximately 20% of the distance from the head of fibula to the lateral malleolus, starting from the head of fibula.16 Intramuscular electrodes were inserted under ultrasound guidance. The process of fine-wire electrode construction and positioning of wires in vivo was undertaken in accordance with previous work.12,17,18 Tibialis anterior and medial gastrocnemius EMG was recorded with the use of DE-3.1 surface electrodes (Delsys Inc., Boston, USA). The electrodes featured a double differential 3-bar type configuration with silver electrode and an inter-electrode distance of 10 mm. The application of surface electrodes followed the recommendations of SENIAM.19 For tibialis anterior, the surface electrode was placed at approximately 20% of the distance from the tuberosity of tibia to the inter-malleoli line, starting from the tuberosity of tibia.19 For medial gastrocnemius, the surface electrode was placed
Fig. 2. Diagram illustrates the two sequences of intervention during EMG testing. Participants were allocated intervention order (A) or (B) from a random number table. Intervention order (A) involved; (1) barefoot condition, (2) ankle brace condition, and (3) augmented low-Dye (ALD) condition. Intervention order (B) involved; (1) barefoot condition, (2) ALD condition, and (3) ankle brace condition.
M.M. Franettovich et al. / Journal of Science and Medicine in Sport 15 (2012) 8–13
11
trials along a 9 m walkway. Six trials were recorded for each condition. Any trial exceeding ±5% of the average warm-up speed was excluded and the trial was repeated. The raw EMG signal was passed through a differential amplifier at a gain of 1000 with a sampling frequency of 2 kHz. A band pass filter (built into the amplifier; Delsys Inc., Boston, USA) of 20–2000 Hz was applied to the intramuscular electrodes and 20–450 Hz for the surface electrodes. EMG and footswitch data were analysed from the 3rd or 4th stride depending on the quality of the footswitch signal. Two consecutive strides (i.e. comprising three consecutive heel contacts from the ipsilateral limb) were analysed for each trial and averaged from the last four of six trials for each speed (i.e. four average gait cycles derived from 8 ipsilateral steps). Two EMG parameters were analysed for each muscle: (i) time of peak amplitude; and (ii) peak amplitude. These parameters have been utilised in previous single-session investigations.12,17,18,20 The following phases of the gait cycle were assessed (based on when these muscles are most active in normal-arched feet): tibialis posterior and peroneus longus – combined midstance/propulsion phase; tibialis anterior – contact phase; medial gastrocnemius – combined midstance/propulsion phase.18 Skewness and kurtosis values indicated that the data was normally distributed. To test for differences between conditions, a series of one-way repeated measure ANOVA tests were conducted. Where data violated the assumption for sphericity as determined by non-significant results (p < 0.05) for the Mauchley’s test, the F-ratio and degrees of freedom were taken from the Greenhouse–Geisser epsilon. To account for multiple comparisons, statistically significant univariate F-statistics were evaluated with Bonferroni post hoc analysis (p = 0.05). The percentage mean difference, 98% confidence intervals (98% CI) and effect sizes were calculated for significant post hoc findings. Effect size (d) was computed as a ratio of the mean change score divided by the standard deviation of the baseline scores. Cohen21 has suggested that an effect size of 0.20 or less represents a small change; 0.50 represents a moderate change; and 0.80 represents a large change.
3. Results Walking velocity was consistent between walking trials and conditions (p = 0.995). The ANOVA detected statistically significant differences for within-participant effects for peak amplitude and time of peak amplitude for tibialis posterior (p = <0.001, 0.006 respectively), peroneus longus (p = 0.002, 0.017 respectively) and tibialis anterior (p = <0.001, 0.030 respectively). As Fig. 3 illustrates, tibialis posterior peak EMG activation decreased by 22.0% (98% CI: 9.8–34.1%; p = 0.004) with the ankle brace and 33.1% (98% CI: 18.2–47.9%; p < 0.001) with ALD tape, when compared to barefoot. Peak activation was also decreased for peroneus longus by 34.0% (98% CI: 9.8–58.3%; p = 0.019) and 29.4% (98% CI:
Fig. 3. EMG ensemble average for tibialis posterior, peroneus longus and tibialis anterior derived from a single gait cycle for all participants. For clarity, error is not shown. The curves differ slightly to the actual results, as these curves are derived from a single gait cycle for each participant to illustrate the main findings. 0% represents heel contact, 100% represents ipsilateral heel contact.
9.0–49.8%; p = 0.015) and for tibialis anterior by 18.7% (98% CI: 11.4–25.9%; p < 0.001) and 13.1% (98% CI: 6.6–19.5%; p = 0.002) with the ankle brace and ALD tape (respectively), compared to barefoot. Effect size calculations suggest that
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M.M. Franettovich et al. / Journal of Science and Medicine in Sport 15 (2012) 8–13
these differences represent small to moderate changes in peak amplitude (effect sizes ranging from 0.36 to 0.60). Fig. 3 also illustrates that the time of peak EMG amplitude for tibialis posterior occurred 5.3% (98% CI: 1.8–8.7%; p = 0.026) earlier with ALD tape and 4.9% (98% CI: 1.8–8.0%; p = 0.015) earlier with the ankle brace, compared to barefoot. Earlier time of peak EMG amplitude was also observed for tibialis anterior, occurring 0.8% (98% CI: 0.3–1.3%; p = 0.010) earlier with the ankle brace compared to barefoot. Changes in timing of peak EMG amplitude were large for tibialis posterior (effect size = 0.85) and moderate for tibialis anterior (effect size = 0.70). The effect of ALD tape and the ankle brace was only different for tibialis posterior peak EMG activation (p = 0.005), with ALD tape producing a 14.5% (98% CI: 6.4–22.6) reduction compared to the ankle brace.
4. Discussion The findings of this study support the hypothesis that when compared to barefoot walking, ALD taping and ankle bracing reduce activity of the leg muscles during gait. Specifically, we observed that the application of both external ankle supports reduced activity of tibialis anterior, tibialis posterior and peroneus longus. Our results are in agreement with two previous reports that ALD taping reduces muscle activity of tibialis anterior and tibialis posterior.6,7 In contrast, one of these studies observed an increase in peroneus longus activity and a reduction in medial gastrocnemius activity, where as our study reported reduced activity of peroneus longus and no change in medial gastrocnemius activity following tape application.7 One explanation for this discrepancy may be the difference in individuals sampled in each of the studies as Franettovich et al.7 examined the effect of tape on a range of foot types (i.e. no inclusion/exclusion criteria based on foot characteristics), whereas our current study investigated these effects on specifically selected individuals with flat-arched feet (as assessed by radiographic measurement). The reduced activity of peroneus longus that we observed in our study following the application of an ankle brace is similar to previous reports of ankle brace induced reductions in peroneus longus activity during walking and running.22 Our results suggest that the ALD tape and ankle brace modalities utilised in this study may counteract altered muscular activity of selected leg muscles in those with specific musculoskeletal disorders by reducing their level of activation during walking. For example, individuals with stage II posterior tibial tendon dysfunction who exhibit increased activity of tibialis posterior, tibialis anterior and peroneus longus8 may benefit from ALD taping or bracing as it reduces activity in these leg muscles. It is plausible that in reducing activity of these leg muscles, taping or bracing may assist the resolution of symptoms and restoration of function by reducing tissue irritation and inflammation as proposed in the tissue stress model. How-
ever, this proposition would require further investigation in this population. Additionally, by reducing activity of tibialis anterior and tibialis posterior, ALD taping or ankle bracing could be useful in counteracting the increased activity of these specific muscles that has been observed in individuals who exhibit excessively pronated feet.9–12 With regard to the existing literature, the physiological basis of taping and bracing is not fully understood. Reductions in muscle activity following application of the ALD tape and brace could be explained by associated biomechanical effects of the external support, such as reductions of range of motion and/or changes in foot posture and foot mobility.23 Another plausible explanation is that external supports stimulate underlying sensory receptors via surface contact (tape and brace) or stretch of the skin (tape) that alters the sensory input to the central nervous system and subsequently influences its perception and execution of movement.23 Our findings are novel – to our knowledge there are no published studies that have compared anti-pronation taping with ankle bracing. We observed that ALD taping and ankle bracing induced a similar direction and size of effect for most muscles and EMG parameters, except taping had a significantly greater influence on reducing tibialis posterior peak amplitude. These findings may have important implications for clinical practice as they will help guide treatment choices for specific individuals. For example, if specifically aiming to address tibialis posterior overuse, such as in individuals with posterior tibial tendon dysfunction, our results suggest that ALD taping may be preferred over ankle bracing as ALD taping produces greater reductions in tibialis posterior activity. In contrast there may be situations where ankle bracing is preferred, such as an individual with sensitive/fragile skin or an allergy to tape, in which taping would not be a suitable treatment option. As the findings demonstrate that the overall effect of taping and bracing on leg muscle activity is similar, the clinician could consider ankle bracing as a reasonable alternative to taping when aiming to reduce leg muscle activity. One of the strengths of this study is that a rigorous protocol was used for screening foot posture and selecting individuals with flat-arched feet. This provided a reliable and valid method of identifying flat-arched feet. Another strength of this study was the use of intramuscular electrodes for tibialis posterior and peroneus longus which minimises cross-talk in recordings from deep (tibialis posterior) and small (peroneus longus) muscles compared to the use of surface electrodes. A potential limitation of this study, however, was that we investigated muscle activity during barefoot walking rather than shod conditions. However, we believe it was crucial to remove the confounding factor of the shoe to obtain a more robust understanding of effects of the taping and bracing modalities. Whilst we investigated these effects in an asymptomatic cohort, previous research supports the extrapolation of our results to symptomatic cohorts as the effect of ALD tape has been observed to be similar regardless of symptomatic status.7
M.M. Franettovich et al. / Journal of Science and Medicine in Sport 15 (2012) 8–13
5. Conclusion This study suggests that both ALD taping and ankle bracing have clinical utility in reducing muscle activity of tibialis anterior, tibialis posterior and peroneus longus during walking. However, if specifically targeting tibialis posterior, ALD taping has a significantly greater effect in reducing activity. These findings may have important implications for clinical practice as they will help guide treatment choices for specific individuals.
Practical implications
3.
4.
5.
6.
7.
• ALD taping and ankle bracing could be useful in managing overuse and dysfunction of tibialis posterior, tibialis anterior and peroneus longus by reducing their level of activation during walking. • The effect of ALD taping and ankle bracing on muscle activity of the lower limb are similar, with the exception that ALD taping produces a greater reduction in tibialis posterior activity. • These findings will help guide selection of treatment options (i.e. tape or brace) for specific individuals.
10.
Disclosures
13.
This project was supported by a research grant from the Australian Podiatry Education and Research Foundation (APERF).
8.
9.
11.
12.
14.
15.
Acknowledgements We thank NEA International (Netherlands) and Beiersdorf Australia Ltd (Australia) for supplying the braces and tape, respectively.
16. 17.
18.
Appendix A. Supplementary data 19.
Supplementary data associated with this article can be found, in the online version, at doi:10.1016/j.jsams.2011.05.009.
20.
21.
References 22. 1. Radford JA, Landorf KB, Buchbinder R, et al. Effectiveness of low-dye taping for the short-term treatment of plantar heel pain: a randomised trial. BMC Musculoskel Disord 2006;7:64. 2. Hyland MR, Webber-Gaffney A, Cohen L, et al. Randomised controlled trial of calcaneal taping, sham taping, and plantar fascia stretching for
23.
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the short-term management of plantar heel pain. J Orthop Sports Phys Ther 2006;36(6):364–371. Landorf KB, Radford JA, Keenan AM, et al. Effectiveness of low-dye taping for the short-term management of plantar fasciitis. J Am Podiatr Med Assoc 2005;95(6):525–530. Smith M, Brooker S, Vicenzino B, et al. Use of anti-pronation taping to assess suitability of orthotic prescription: case report. Aust J Physiother 2004;50(2):111. Meier K, McPoil TG, Cornwall MW. Use of antipronation taping to determine foot orthoses prescription: a case series. Res Sports Med 2008;16:257–271. Franettovich M, Chapman A, Vicenzino B. Tape that increases medial longitudinal arch height also reduces leg muscle activity: a preliminary study. Med Sci Sports Exerc 2008;40(4):593–600. Franettovich M, Chapman AR, Blanch P, et al. Augmented low-dye tape alters foot mobility and neuromotor control of gait in individuals with and without exercise related leg pain. J Foot Ankle Res 2010;3:5. Ringleb SI, Kavros SJ, Kotajarvi BR, et al. Changes in gait associated with acute stage ii posterior tibial tendon dysfunction. Gait Posture 2007;25:555–564. Gray EG, Basmajian JV. Electromyography and cinematography of leg and foot (“normal” and flat) during walking. Anat Rec 1968;161(1):1–15. Gray ER. The role of leg muscles in variations of the arches in normal and flat feet. Phys Ther 1969;49(10):1084– 1088. Hunt AE, Smith RM. Mechanics and control of the flat versus normal foot during the stance phase of walking. Clin Biomech 2004;19:391– 397. Murley GS, Menz HB, Landorf KB. Foot posture influences the electromyographic activity of selected lower limb muscles during gait. J Foot Ankle Res 2009;2(35):1–9. Murley GS, Menz HB, Landorf KB. A protocol for classifying normaland flat-arched foot posture for research studies using clinical and radiographic measurements. J Foot Ankle Res 2009;2(22):1–13. Franettovich M, Chapman A, Blanch P, et al. Continual use of augmented low-dye taping increases arch height in standing but does not influence neuromotor control of gait. Gait Posture 2010;31(2):247–250. Franettovich M, Chapman AR, Blanch P, et al. Altered neuromuscular control in individuals with exercise-related leg pain. Med Sci Sports Exerc 2010;42(3):546–555. Leis AA, Trapani VC. Atlas of electromyography. Oxford: Oxford University Press; 2000. Murley GS, Buldt AK, Trump PJ, et al. Tibialis posterior emg activity during barefoot walking in people with neutral foot posture. J Electromyogr Kinesiol 2009;19(2):e69–e77. Murley GS, Menz HB, Landorf KB, et al. Reliability of lower limb electromyography during overground walking: a comparison of maximal- and sub-maximal normalisation techniques. J Biomech 2010;43(4):749–756. Hermens HJ, Freriks B, Merletti R, et al. Seniam 8 – European recommendations for surface electromyography. 2nd ed. Enschede: Roessingh Research and Development;; 1999. Murley GS, Bird AR. The effect of three levels of foot orthotic wedging on the surface electromyographic activity of selected lower limb muscles during gait. Clin Biomech 2006;21(10):1074–1080. Cohen J. Statistical power analysis for the behavioral sciences. 2nd ed. Hillsdale, NJ: L. Erlbaum Associates; 1988. Konradsen L, Hojsgaard C. Pre-heel-strike peroneal muscle activity during walking and running with and without an external ankle support. Scand J Med Sci Sports 1993;3:99–103. Franettovich M, Chapman A, Blanch P, et al. A physiological and psychological basis for anti-pronation taping from a critical review of the literature. Sports Med 2008;38(8):617–631.
Journal of Science and Medicine in Sport 15 (2012) 8–13
Original research
A comparison of augmented low-Dye taping and ankle bracing on lower limb muscle activity during walking in adults with flat-arched foot posture Melinda M. Franettovich a,∗ , George S. Murley b,c , Bianca S. David b , Adam R. Bird b,c a
School of Physiotherapy, Australian Catholic University, Australia b Department of Podiatry, La Trobe University, Australia c Musculoskeletal Research Centre, La Trobe University, Australia
Received 8 October 2010; received in revised form 26 April 2011; accepted 20 May 2011
Abstract Objective: To compare the effect of taping and bracing on lower limb muscle activity during gait. Design: Cross-sectional laboratory study. Methods: Twenty-seven asymptomatic adults with flat-arched foot posture were recruited to this study. They walked over-ground under three randomly allocated conditions: (i) barefoot; (ii) augmented low-Dye taping; (iii) replaceable ankle brace. Electromyographic (EMG) activity from tibialis posterior, tibialis anterior, peroneus longus and medial gastrocnemius was measured for each condition. Peak EMG amplitude and time of peak EMG amplitude were assessed from stance phase data. A series of one-way repeated measure analysis of variance followed by Bonferroni post hoc tests were undertaken (α = 0.05). Results: Tibialis posterior peak EMG amplitude decreased by 22% and 33% with bracing and taping (respectively), compared to barefoot. Peak amplitude was also decreased for peroneus longus by 34% and 30% and for tibialis anterior by 19% and 13% with bracing and taping (respectively), compared to barefoot. Small significant changes in time of peak EMG amplitude were found for tibialis posterior and tibialis anterior with taping and bracing compared to barefoot. The effect of taping and bracing was only different for tibialis posterior peak EMG amplitude, with tape producing a 15% reduction compared to bracing. Conclusion: The augmented low-Dye tape and replaceable ankle brace used in this study could be useful in managing overuse and dysfunction of selected leg muscles, particularly tibialis posterior, by reducing their level of activation during walking. © 2011 Sports Medicine Australia. Published by Elsevier Ltd. All rights reserved. Keywords: Athletic tape; Braces; Electromyography; Gait; Ankle
1. Introduction External ankle support, in the form of taping and bracing, has long been used to assist with management of various lower limb conditions. A key distinction between taping and bracing modalities is that tape is adhered to the skin, whereas bracing is usually held in place by laces or Velcro®TM straps. Over time, taping and bracing have evolved to include features that reduce foot pronation. Anti-pronation taping has demonstrated efficacy in reducing pain in individuals with heel pain,1,2 plantar fasciitis,3 and there is preliminary evidence from case reports for its use in Achilles tendinopathy,4 iliotibial band friction syndrome,5 anterior knee pain,5 and ∗
Corresponding author. E-mail address: [email protected] (M.M. Franettovich).
medial tibial stress syndrome.5 With this in mind, several laboratory-based studies have investigated the biomechanical and neuromuscular effects of this modality, primarily to develop understanding of underlying mechanisms linking anti-pronation taping with positive clinical outcomes. An anti-pronation taping technique, termed the augmented low-Dye, has been reported to reduce activity of tibialis anterior, tibialis posterior and medial gastrocnemius in individuals with varied foot types, as well as those with and without musculoskeletal pain.6,7 Despite the clinical use of ankle bracing in the management of lower limb conditions, it remains unclear what effect anti-pronation bracing has on individuals with existing injuries. Given the neuromuscular effects of anti-pronation taping described above, this modality may counteract altered muscular activity associated in those with specific musculoskeletal disorders as well as with
1440-2440/$ – see front matter © 2011 Sports Medicine Australia. Published by Elsevier Ltd. All rights reserved. doi:10.1016/j.jsams.2011.05.009
M.M. Franettovich et al. / Journal of Science and Medicine in Sport 15 (2012) 8–13
altered foot posture. Firstly, there is preliminary evidence that altered neuromuscular control of the leg is associated with musculoskeletal disorders, such as tibialis posterior tendon dysfunction.8 Ringleb et al.8 investigated muscle activation in four females with stage II posterior tibial tendon dysfunction and reported that these individuals exhibited increased activity of tibialis posterior, tibialis anterior, peroneus longus and medial gastrocnemius during walking, compared to healthy controls. The authors hypothesised that the increase in muscle activity may be associated with the development of a valgus foot deformity (i.e. flattening of the medial arch), although conclusions from this study are limited due to the small sample size. Secondly, previous studies have reported increased activity of some leg muscles (tibialis posterior, tibialis anterior, toe flexors, calf) in individuals who exhibit excessive pronation.9–12 With the growing body of evidence that foot posture and musculoskeletal injuries systematically alter muscle activity during gait, there is a need to develop interventions that optimise muscle activity. To our knowledge, no published research has investigated the effect of anti-pronation bracing on tibialis posterior, one of the primary muscles that counteracts foot pronation during normal gait. It is of interest to clinicians to investigate and compare the effect of antipronation taping and bracing on lower limb muscle activity during gait as this may provide further information when deciding which modality is the best choice for treatment of lower limb overuse injuries. For example, taping can be problematic for some individuals such as those with allergic reactions to tape and those with vulnerable skin (e.g. elderly, presence of skin conditions such as psoriasis or eczema). For these individuals, bracing may be a more suitable treatment when support is needed for extended periods of time. Other comparisons between taping and bracing worth consideration relate to the skill and training required for application (whether an individual can apply independently at home) and the cost of the intervention (taping may be more cost effective in the short term, but bracing may be a more cost effective alternative for longer periods of time). Therefore, the aim of this study was to investigate whether anti-pronation taping and bracing has an effect on muscle activity of the lower leg when compared to barefoot walking in individuals with flat-arched foot posture. It was hypothesised that both the tape and brace would reduce the requirement of the muscular system (by providing external support) and therefore reduce the activity of lower leg muscles, particularly tibialis posterior, during gait.
2. Methods Twenty-seven adults with flat-arched feet (13 males and 14 females) aged 18–37 years were recruited to this study (Supplementary File 1). The participants were without symptoms of macrovascular (e.g. angina, stroke, peripheral vascular disease) and/or neuromuscular disease, or any
9
biomechanical abnormalities that affected their ability to walk. Ethical approval was obtained for the study from the La Trobe University Human Ethics Committee (Ethics ID: FHEC06/205) and it was registered with the Radiation Safety Committee of the Victorian Department of Human Services. A foot screening protocol was used to include only participants with flat-arched foot posture – those most likely to benefit from anti-pronation taping or bracing. The foot screening protocol included both clinical and radiographic measures of foot posture.13 This protocol was derived from normative foot posture values for two clinical measurements (the arch index and normalised navicular height to truncated foot length) and four angular measurements obtained from antero-posterior and lateral X-rays (talus-second metatarsal angle, talonavicular coverage angle, calcaneal inclination angle and calcaneal-first metatarsal angle). To qualify for the flat-arched group, participants had to exhibit an arch index or normalised navicular height to truncated foot length measurement greater than two standard deviations from mean values obtained for people with normal-arched feet.13 Furthermore, their radiographic measurements had to be greater than one standard deviation from the mean values obtained for people with normal-arched feet for either the sagittal and or transverse plane measurements (Supplementary File 1).13 The X-rays were performed in accordance with the Australian Radiation Protection and Nuclear Safety Agency Code of Practice for the Exposure of Humans to Ionizing Radiation for Research Purposes (2005). Two types of anti-pronation external ankle support were investigated: (i) augmented low-Dye tape (ALD) and (ii) a commercially available prefabricated semi-rigid ankle brace (Push® Aequi, NEA International, Netherlands). ALD tape has been used in several gait studies.6,7,14,15 It features the low-Dye technique (spurs and mini-stirrups) with the addition of three reverse sixes and two calcaneal slings anchored to the lower third of the leg. The tape is applied with the talocrural joint in plantigrade and the rearfoot in approximately two-thirds of the total available range of motion of supination. A rigid sports tape (38 mm zinc oxide adhesive, Leukosport BDF) was used (Fig. 1). The brace featured a plastic semi-rigid medial ankle support, one diagonal band with Velcro® over the antero-lateral aspect of the ankle, and two adjustable elastic straps with Velcro® that wrapped from the medial and lateral aspects of the rearfoot (Fig. 1). Participants attended a single testing session in the EMG gait laboratory. Bipolar fine-wire intramuscular electrodes were used to record the EMG signal from tibialis posterior and peroneus longus. The electrodes were fabricated from 75 m Teflon® coated stainless steel wire (A-M Systems, Washington, USA) with 1 mm of insulation stripped to form the recording surface of the two wires. The electrode wires were inserted into a 23 gauge sterilized single use hypodermic needle with the exposed electrode tips bent 3 mm and 5 mm to prevent the contact areas from touching during recording. For tibialis posterior, the intramuscular electrode was inserted at a distance of approximately 50% between the popliteus
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at approximately 25% of the distance from the medial side of the popliteus cavity to the calcaneal tubercle.19 The temporal characteristics of the walking cycle were measured using circular force sensitive resistors (footswitches) with a diameter of 13 mm (Model: 402, Interlink Electronics, California, USA). These were placed on the plantar surface of the interphalangeal joint of the hallux and the most posterior plantar aspect of the calcaneus to record the timing of heel contact, toe contact, heel off and toe off. During testing, participants first walked barefoot and then under two randomly allocated conditions: (i) barefoot with ALD taping; or (ii) barefoot with a replaceable ankle brace (Figs. 1 and 2). Participants walked continuously for three minutes with the brace and tape just prior to recording, to ensure the participant was comfortable and to reduce any cross-over effect from the respective condition (Fig. 2). They were instructed to walk at their self-selected walking speed, which was established following a warm-up period from two
Fig. 1. The ankle brace (top) and augmented low-Dye (ALD) taping method (bottom) are shown.
cavity to the medial malleolus.16 Peroneus longus – the intramuscular electrode was inserted at approximately 20% of the distance from the head of fibula to the lateral malleolus, starting from the head of fibula.16 Intramuscular electrodes were inserted under ultrasound guidance. The process of fine-wire electrode construction and positioning of wires in vivo was undertaken in accordance with previous work.12,17,18 Tibialis anterior and medial gastrocnemius EMG was recorded with the use of DE-3.1 surface electrodes (Delsys Inc., Boston, USA). The electrodes featured a double differential 3-bar type configuration with silver electrode and an inter-electrode distance of 10 mm. The application of surface electrodes followed the recommendations of SENIAM.19 For tibialis anterior, the surface electrode was placed at approximately 20% of the distance from the tuberosity of tibia to the inter-malleoli line, starting from the tuberosity of tibia.19 For medial gastrocnemius, the surface electrode was placed
Fig. 2. Diagram illustrates the two sequences of intervention during EMG testing. Participants were allocated intervention order (A) or (B) from a random number table. Intervention order (A) involved; (1) barefoot condition, (2) ankle brace condition, and (3) augmented low-Dye (ALD) condition. Intervention order (B) involved; (1) barefoot condition, (2) ALD condition, and (3) ankle brace condition.
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trials along a 9 m walkway. Six trials were recorded for each condition. Any trial exceeding ±5% of the average warm-up speed was excluded and the trial was repeated. The raw EMG signal was passed through a differential amplifier at a gain of 1000 with a sampling frequency of 2 kHz. A band pass filter (built into the amplifier; Delsys Inc., Boston, USA) of 20–2000 Hz was applied to the intramuscular electrodes and 20–450 Hz for the surface electrodes. EMG and footswitch data were analysed from the 3rd or 4th stride depending on the quality of the footswitch signal. Two consecutive strides (i.e. comprising three consecutive heel contacts from the ipsilateral limb) were analysed for each trial and averaged from the last four of six trials for each speed (i.e. four average gait cycles derived from 8 ipsilateral steps). Two EMG parameters were analysed for each muscle: (i) time of peak amplitude; and (ii) peak amplitude. These parameters have been utilised in previous single-session investigations.12,17,18,20 The following phases of the gait cycle were assessed (based on when these muscles are most active in normal-arched feet): tibialis posterior and peroneus longus – combined midstance/propulsion phase; tibialis anterior – contact phase; medial gastrocnemius – combined midstance/propulsion phase.18 Skewness and kurtosis values indicated that the data was normally distributed. To test for differences between conditions, a series of one-way repeated measure ANOVA tests were conducted. Where data violated the assumption for sphericity as determined by non-significant results (p < 0.05) for the Mauchley’s test, the F-ratio and degrees of freedom were taken from the Greenhouse–Geisser epsilon. To account for multiple comparisons, statistically significant univariate F-statistics were evaluated with Bonferroni post hoc analysis (p = 0.05). The percentage mean difference, 98% confidence intervals (98% CI) and effect sizes were calculated for significant post hoc findings. Effect size (d) was computed as a ratio of the mean change score divided by the standard deviation of the baseline scores. Cohen21 has suggested that an effect size of 0.20 or less represents a small change; 0.50 represents a moderate change; and 0.80 represents a large change.
3. Results Walking velocity was consistent between walking trials and conditions (p = 0.995). The ANOVA detected statistically significant differences for within-participant effects for peak amplitude and time of peak amplitude for tibialis posterior (p = <0.001, 0.006 respectively), peroneus longus (p = 0.002, 0.017 respectively) and tibialis anterior (p = <0.001, 0.030 respectively). As Fig. 3 illustrates, tibialis posterior peak EMG activation decreased by 22.0% (98% CI: 9.8–34.1%; p = 0.004) with the ankle brace and 33.1% (98% CI: 18.2–47.9%; p < 0.001) with ALD tape, when compared to barefoot. Peak activation was also decreased for peroneus longus by 34.0% (98% CI: 9.8–58.3%; p = 0.019) and 29.4% (98% CI:
Fig. 3. EMG ensemble average for tibialis posterior, peroneus longus and tibialis anterior derived from a single gait cycle for all participants. For clarity, error is not shown. The curves differ slightly to the actual results, as these curves are derived from a single gait cycle for each participant to illustrate the main findings. 0% represents heel contact, 100% represents ipsilateral heel contact.
9.0–49.8%; p = 0.015) and for tibialis anterior by 18.7% (98% CI: 11.4–25.9%; p < 0.001) and 13.1% (98% CI: 6.6–19.5%; p = 0.002) with the ankle brace and ALD tape (respectively), compared to barefoot. Effect size calculations suggest that
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these differences represent small to moderate changes in peak amplitude (effect sizes ranging from 0.36 to 0.60). Fig. 3 also illustrates that the time of peak EMG amplitude for tibialis posterior occurred 5.3% (98% CI: 1.8–8.7%; p = 0.026) earlier with ALD tape and 4.9% (98% CI: 1.8–8.0%; p = 0.015) earlier with the ankle brace, compared to barefoot. Earlier time of peak EMG amplitude was also observed for tibialis anterior, occurring 0.8% (98% CI: 0.3–1.3%; p = 0.010) earlier with the ankle brace compared to barefoot. Changes in timing of peak EMG amplitude were large for tibialis posterior (effect size = 0.85) and moderate for tibialis anterior (effect size = 0.70). The effect of ALD tape and the ankle brace was only different for tibialis posterior peak EMG activation (p = 0.005), with ALD tape producing a 14.5% (98% CI: 6.4–22.6) reduction compared to the ankle brace.
4. Discussion The findings of this study support the hypothesis that when compared to barefoot walking, ALD taping and ankle bracing reduce activity of the leg muscles during gait. Specifically, we observed that the application of both external ankle supports reduced activity of tibialis anterior, tibialis posterior and peroneus longus. Our results are in agreement with two previous reports that ALD taping reduces muscle activity of tibialis anterior and tibialis posterior.6,7 In contrast, one of these studies observed an increase in peroneus longus activity and a reduction in medial gastrocnemius activity, where as our study reported reduced activity of peroneus longus and no change in medial gastrocnemius activity following tape application.7 One explanation for this discrepancy may be the difference in individuals sampled in each of the studies as Franettovich et al.7 examined the effect of tape on a range of foot types (i.e. no inclusion/exclusion criteria based on foot characteristics), whereas our current study investigated these effects on specifically selected individuals with flat-arched feet (as assessed by radiographic measurement). The reduced activity of peroneus longus that we observed in our study following the application of an ankle brace is similar to previous reports of ankle brace induced reductions in peroneus longus activity during walking and running.22 Our results suggest that the ALD tape and ankle brace modalities utilised in this study may counteract altered muscular activity of selected leg muscles in those with specific musculoskeletal disorders by reducing their level of activation during walking. For example, individuals with stage II posterior tibial tendon dysfunction who exhibit increased activity of tibialis posterior, tibialis anterior and peroneus longus8 may benefit from ALD taping or bracing as it reduces activity in these leg muscles. It is plausible that in reducing activity of these leg muscles, taping or bracing may assist the resolution of symptoms and restoration of function by reducing tissue irritation and inflammation as proposed in the tissue stress model. How-
ever, this proposition would require further investigation in this population. Additionally, by reducing activity of tibialis anterior and tibialis posterior, ALD taping or ankle bracing could be useful in counteracting the increased activity of these specific muscles that has been observed in individuals who exhibit excessively pronated feet.9–12 With regard to the existing literature, the physiological basis of taping and bracing is not fully understood. Reductions in muscle activity following application of the ALD tape and brace could be explained by associated biomechanical effects of the external support, such as reductions of range of motion and/or changes in foot posture and foot mobility.23 Another plausible explanation is that external supports stimulate underlying sensory receptors via surface contact (tape and brace) or stretch of the skin (tape) that alters the sensory input to the central nervous system and subsequently influences its perception and execution of movement.23 Our findings are novel – to our knowledge there are no published studies that have compared anti-pronation taping with ankle bracing. We observed that ALD taping and ankle bracing induced a similar direction and size of effect for most muscles and EMG parameters, except taping had a significantly greater influence on reducing tibialis posterior peak amplitude. These findings may have important implications for clinical practice as they will help guide treatment choices for specific individuals. For example, if specifically aiming to address tibialis posterior overuse, such as in individuals with posterior tibial tendon dysfunction, our results suggest that ALD taping may be preferred over ankle bracing as ALD taping produces greater reductions in tibialis posterior activity. In contrast there may be situations where ankle bracing is preferred, such as an individual with sensitive/fragile skin or an allergy to tape, in which taping would not be a suitable treatment option. As the findings demonstrate that the overall effect of taping and bracing on leg muscle activity is similar, the clinician could consider ankle bracing as a reasonable alternative to taping when aiming to reduce leg muscle activity. One of the strengths of this study is that a rigorous protocol was used for screening foot posture and selecting individuals with flat-arched feet. This provided a reliable and valid method of identifying flat-arched feet. Another strength of this study was the use of intramuscular electrodes for tibialis posterior and peroneus longus which minimises cross-talk in recordings from deep (tibialis posterior) and small (peroneus longus) muscles compared to the use of surface electrodes. A potential limitation of this study, however, was that we investigated muscle activity during barefoot walking rather than shod conditions. However, we believe it was crucial to remove the confounding factor of the shoe to obtain a more robust understanding of effects of the taping and bracing modalities. Whilst we investigated these effects in an asymptomatic cohort, previous research supports the extrapolation of our results to symptomatic cohorts as the effect of ALD tape has been observed to be similar regardless of symptomatic status.7
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5. Conclusion This study suggests that both ALD taping and ankle bracing have clinical utility in reducing muscle activity of tibialis anterior, tibialis posterior and peroneus longus during walking. However, if specifically targeting tibialis posterior, ALD taping has a significantly greater effect in reducing activity. These findings may have important implications for clinical practice as they will help guide treatment choices for specific individuals.
Practical implications
3.
4.
5.
6.
7.
• ALD taping and ankle bracing could be useful in managing overuse and dysfunction of tibialis posterior, tibialis anterior and peroneus longus by reducing their level of activation during walking. • The effect of ALD taping and ankle bracing on muscle activity of the lower limb are similar, with the exception that ALD taping produces a greater reduction in tibialis posterior activity. • These findings will help guide selection of treatment options (i.e. tape or brace) for specific individuals.
10.
Disclosures
13.
This project was supported by a research grant from the Australian Podiatry Education and Research Foundation (APERF).
8.
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12.
14.
15.
Acknowledgements We thank NEA International (Netherlands) and Beiersdorf Australia Ltd (Australia) for supplying the braces and tape, respectively.
16. 17.
18.
Appendix A. Supplementary data 19.
Supplementary data associated with this article can be found, in the online version, at doi:10.1016/j.jsams.2011.05.009.
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21.
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