A Quasi-experimental study with pretest – posttest design was conducted to evaluate the effects of two anti-pronation taping models on the maximum plantar pressure and ground reaction force distribution related to individuals with flat foot before and after a period of fatigue.
Twenty flat footed individuals (male and female) participated in this study. The age (mean ± standard deviation), height, mass, and foot size of the participants respectively were 22.4 ± 2.0 years, 171 ± 6.8 cm, 71.4 ± 8.4 kg, and 43.3 ± 2.6. An a priori sample size estimate using an α = 0.05, a β = 0.20, a within-factor correlation of 0.7, and a partial eta squared effect size statistic of 0.06 (moderate effect size) was conducted using G*Power software (Version 3.1, University of Dusseldorf, Dusseldorf, Germany) 30,33−35. This sample size estimate indicated that a minimum of 20 subjects was needed in order to ensure adequate power considering our planned statistical analysis (repeated measures analysis of variance).
The protocol of the study was approved by the Institutional Review Board at Kharazmi University, Tehran, Iran. The study was conducted in accordance with the Declaration of Helsinki and the International Committee of Medical Journal Editors after approval by the Ethics Committee in Research of Sport Sciences Research Institute of Iran. Before enrollment volunteered athletes were informed of the risks associated with the study, and then the signed informed consent document was obtained from all the participants. Participants had the right to withdraw from the study at any time without any consequences.
Inclusion criteria consisted of people with navicular drop greater than 10 mm 6 and being able to walk pain free 30. Exclusion criteria included any sensitivity or abnormal reaction to rigid taping, such as redness, having rash or discomfort 6,30, lower limb injuries in the past six months 6,30, surgery on the lower limb 33, and neurological disorders 33. Before measuring the variables, a summary of the research design was explained to the subjects. They were then initially screened based on the research inclusion and exclusion criteria, and those who were voluntarily willing to cooperate completed the consent form. Having met the inclusion criteria, the included subjects were let to enter the laboratory for performing the testing process based on the previously announced time. On the test day, their background information including height, weight, and age were recorded in the demographic data collection form.
Initial Subjective Interview
The subjects' demographic information, disease details and duration if applied, medical history and related injuries were determined through personal interviews with the subjects. The interviews were conducted by a researcher with more than ten years of experiences in assessing and rehabilitating musculoskeletal disorders.
Maximum plantar pressure and ground reaction force were recorded while walking in three different conditions (untaping, low-dye taping and reverse-6 taping) as well as in two time points, before and after fatigue; the data collection has been randomly conducted through three different days with one-week interval.
Prior to each measurement session, the participants were first familiar with the laboratory environment, and the testing procedures e.g. walking, and/or stepping at their desired speed in the designated path. Five walking repetitions were recorded on the foot-scan device in both the pre-and post-fatigue conditions, along with applying each of three intended taping conditions (untaping, low-dye taping and reverse-6 taping). In this study, it was tried to control all the testing conditions, including testing time points, conditions, fatigue and other factors affecting the results so that the testing conditions were similarly performed in all three days.
How to record maximum plantar pressure variables and maximum ground reaction force: Foot-scan device (RsScan international, Belgium, 40–100 cm, 8192 sensors, 253 Hz) was used to record the variables related to plantar pressure and force distribution during walking; foot-scan 7 gait generation software was then used to analyze the obtained data. The foot-scan device was located in the center of a 12-meter-long path to record individuals' natural gait. To record the participants’ plantar pressure and force distribution, they were asked to walk in a certain direction at their normal speed, and walk over the foot-scan. To avoid changes in the step length, they were asked to go back and forth several times, and were asked not to change their gait pattern or not to adjust their steps before going on the foot-scan so that their second step was exactly felling on the foot-scan. Each gait test was repeated three times, and a one minute rest interval between two gait recordings was considered. In order to analyze the studied variables, foot-scan 7 gait generation software automatically divided the foot sole into ten anatomical areas including first toe (Toe 1), second to fifth toes (Toe 2–5), first to fifth metatarsal heads (Meta1-5), midfoot, medial heel, and lateral heel (see Fig. 1). Then, the dependent variables of maximum plantar pressure and force respectively in terms of N/cm2 and N were recorded in the ten foot sole areas using the Foot-scan device (RsScan International, Belgium, 40 _ 100 cm, 8192 sensors, 253 Hz) 35.
Figure 1 about here.
Low-dye taping: the low-dye taping technique consisted of a rigid and sticky white LP tape (LP athletic tape comprises of 100% cotton/zinc oxide professional grade athletic tape. Width: 38 mm, company: LP support UK). In order to apply the taping, the participants’ ankle was placed in a neutral position. Longitudinal anchor strips were pulled lateral-to-medial along the lateral aspect of the foot starting at the head of the fifth metatarsal and ending at the head of the first metatarsal. Then, the transverse arch support strip was pulled lateral-to-medial along the plantar surface of the foot starting at the anterior surface of the calcaneus to the heads of the metatarsals. Finally, the taping was completed with an additional longitudinal anchor strip applied to help secure the transverse arch support strips (see Fig. 2) 36.
Reverse-6 Taping: reverse-6, which its effect has already been shown to increase the navicular height, included a LP strip (LP athletic tape comprises of 100% cotton/zinc oxide professional grade athletic tape. Width: 38 mm, company: LP support UK), started from the medial malleolus and coursed anterolaterally over the foot, and then, it continued from under the midfoot up to the medial side of the foot and distal leg to support the mid and rear-foot. The ankle and foot were placed in a slight supination position in order to effectively apply the taping (see Fig. 2) 37.
Figure 2 about here.
The fatigue protocol included running on a treadmill. Having familiarized the participants with the test conditions and the fatigue protocol, each participant began to walk on a treadmill at a speed of 6-km/h. Participants were asked to report perceived exertion according to the 15-point Borg Scale while walking on treadmill (6–20). Furthermore, participants' heart rate was simultaneously monitored. Speed was increased in increments of 1 km/h every 2 min until an intensity of 13 on the Borg scale was reached. After reporting a score of 13, subjects continued to run at the given steady state speed until a Borg score of 17 or 80% of their age related heart rate peak was reached. As reached this very point, they continued to run for 2 additional minutes. Then, the participants were immediately tested for walking on the foot scan to evaluate the effect of foot taping on the research variables in the fatigue condition. Finally, the participants performed the cool-down protocol at a self-selected speed. As a further matter, in order to equalize the test conditions for all the participants and to prevent the bias in this regard, they were all provided with a new neutral running shoes for the running-induced fatigue protocol 35.
Descriptive statistics was used to describe the data (mean and standard deviation) for all the variables and participants’ demographic information. Shapiro-Wilk test was also used to measure normality of data distribution. A 3*2 factorial ANOVA (three groups consisting of control vs. revers-6 vs. low dye taping * time points consisting of pre vs. post fatigue) was used to compare the taping and fatigue-caused main effects, and their interactive effects. If the variance analysis results were significant, a Bonferroni post hoc test was used to compare taping levels between different treatments. All the statistical comparisons were performed using SPSS software version 20, at a significance level set at ≤ 0.05.