Progressive tension protocol for muscle strength with Kinesio tape in runners - double-blind randomized clinical trial

Abstract Introduction Kinesio tape (KT), although frequently used in sports, is still a matter of debate, and the results of studies that evaluated its effects on muscle strength (MS) in athletes are still inconclusive and contradictory. Objective To evaluate the effect of a progressive KT tension protocol on knee MS in runners over an eight-week intervention. Methods Clinical trial involving 49 runners of both sexes randomized into two groups: KT (KT with progressive tension protocol) and placebo (KT without tension). The MS of knee flexors and extensors was evaluated by isokinetic dynamometer (60º/s and 90º/s) at four moments: (1) without KT; (2) with KT and without tension; (3) without KT (after 8 weeks after of intervention); (4) with KT and with tension (after 8 weeks after of intervention). Inter- and intra-group comparisons were made. The significance level adopted was 95% (p < 0.05). Results There were no significant differences in MS between the groups at any of the evaluated moments. There was a statistically significant difference in MS (60º/s) in both groups (KT and placebo) when comparing moments 4 and 2 for knee flexors, and in the placebo group between moments 4 and 2 and moments 4 and 3 for knee extensors. Conclusion The progressive tension protocol of KT was not able to intervene in the SM gain of knee flexors and extensors of runners in inter and intragroup comparisons.


Introduction
Invented by Japanese chiropractor Kenzo Kase in the 1970s, Kinesio Tape (KT) or Elastic Bandage (EB) had its first worldwide appearance during the Seoul Olympic Games in 1988 and became popular after the 2008 Olympic Games in Beijing, where US beach volleyball gold medalist Kerri Walsh appeared wearing the tapes after a rotator cuff injury to her right shoulder.1,2 Clinical trials using KT have been published frequently, and among the various conditions investigated are studies that aim to assess the effects of KT on muscle strength in different populations and conditions.1,2 KT consists of a colored, adhesive tape (no latex), 100% cotton, with elasticity.[1][2][3] It can be applied directly to the skin and tensioned longitudinally to up to 140% of its original length (varying by brand).It can last for three to five days on the skin, and can even be used in water.1,3 The therapist decides which location, technique and tension level will be used on each patient according to their specific conditions.1,3 The combination of the elasticity of KT and its application to elongated muscles creates convolutions (waves formed in the skin after the application of KT in stretching tension) in the upon return to the neutral position and it is believed that these convolutions reduce pressure on the mechanoreceptors located below the dermis, thus reducing nociceptive stimuli and, consequently, pain.3 Convolutions are also believed to alter muscle recruitment through inhibitory and excitatory (facilitatory) neuromuscular mechanisms, depending on the direction of tape application.
When KT is applied at the muscle insertion and extended with adequate tension to its origin, it is proposed that the regression effect can inhibit motor neurons by stretching Golgi tendon organs at the distal end of the muscle.1,2,4,5 When applied in the opposite way, from the origin to the insertion of the muscle, it is believed that it can increase the contraction of the muscle spindle reflex and facilitate the contraction of the muscle, which would therefore result in an increase in muscle activity and consequently in muscle activity.1,2,4,5 There is also the hypothesis that the cutaneous stimulation provided by the tape, involving type II mechanoreceptors located in the depth of the dermis, may induce greater recruitment of motor units and facilitate muscle strength gain.(intervention group), since the first week of application must be performed without tension so that the patient adapts to KT (Figure 1).

Running workouts
The

Initial and final assessment
The muscle strength of the right knee extensors and flexors was evaluated using a Biodex Multi-Joint Pro isokinetic dynamometer at an angular velocity of 60° and 90° per second, respectively.Five repetitions were performed for each angulation analyzed (60º/s and 90º/s), with a 30-second rest interval between them, and the highest peak torque of the five repetitions collected was considered for analysis.the tape was immediately applied to the skin of the participant and no contact between the evaluator with this area was made so that there was no decrease in the adhesion capacity of the tape, thus the adhesive protection was not completely removed from the tape before application.
Regarding the application of KT, the base of the tape was applied 5 cm below the origin of the rectus femoris (inferior anterior iliac spine) -without tension in this part of the tape (2 to 3 cm at the beginning) -, going towards its insertion (base of the patella, through the suprapatellar ligament) with or without tension according to the group to which the participant was assigned (Figure 2).
The last 1 or 2 cm of tape was also applied without tension to avoid discomfort, regardless of the group to which they belonged.The tape was applied in "I" ("I-strip"), with the participants in the supine position on the stretcher, with the hip flexed at 30° and the knee flexed at 60° (these angles were measured using a goniometer).KT was applied without tension in the first week of intervention for both groups and tension increased once a week throughout the seven weeks only for the KT group (intervention group), while the placebo group remained tension-free throughout the intervention (Figure 2).
All participants were randomly divided into two groups: • Placebo group -no tension in any of their tape applications; that way, the size of the tape over the applied area was always the same; • KT group (intervention group) -progressive tension over the weeks; this protocol is based on reducing the length of the tape over the weeks, in relation to the size of the applied area (which will always be the same), which generates a longitudinal tension in the tape in relation to the participant's skin (protocol described below, in Figure 3).The percentage of 20% reduction in tension was distributed over the seven weeks of intervention, with the first week of the protocol including the application without tension.Tape reduction was controlled by the formula: (size of skin application area cm *20%/7 weeks = tape size to be cut in each of seven applications from the second week.Tape size and tape application area were calculated in centimeters (protocol described below in Figure 3).

Statistical analysis
Descriptive data were expressed as mean and standard deviation or median and interquartile range.

Results
The characterization of the sample is shown in Table 1 and, as stated, there were no statistical differences between the groups (p ≥ 0.05) for any of the variables analyzed.for knee flexors and extensors.There was no significant difference in intragroup comparisons for 90º/s angular velocity, in both groups (KT and placebo), between any of the evaluated moments, both for knee extensors and flexors.
The intra-and inter-group comparisons in the four evaluation moments are shown in Table 2.There were no significant inter-group differences (between the KT group and placebo group -in all comparisons: p ≥ 0.05) in both angular speeds (60º/s and 90º/s), both Stocco MR et al.
Fisioter Mov.2023;36:e36104 8 In the intragroup comparison (pre-and postintervention), for the angular velocity of 60º/s, there was a significant improvement for the KT group when the moment 4 (8 weeks with KT) and the moment 2 (postimmediate with KT) were compared for knee flexors.
The same occurred in the placebo group.Still in the intragroup comparison, in the placebo group, there significant differences in muscle strength between the groups at any of the angular velocities (60 and 90º/s), both for knee flexors and extensors; (2) there was no statistically significant difference in muscle strength for the 90º/s angular velocity, in both groups in intragroup comparisons (pre-and post-intervention), between any of the evaluated moments, both for extensors and for

Discussion
The aim of this study was to evaluate the effect of a progressive KT tension protocol on knee muscle strength (flexors and extensors) in runners.Therefore, a protocol of progressive tension (progressive increase of 0-20% tension) of KT was carried out over an eight-week intervention, with a weekly application.The main results of this intervention were: (1) there were no statistically  The application of KT is considered safe and presents few adverse events, and when applied correctly, it can still act as a complementary therapy and this study is not intended to discourage its use, only to demonstrate that it alone is not capable of directly intervening in strength gain muscle.

Conclusion
The progressive tension protocol of KT did not present significant effects in relation to the gain in muscle strength of knee flexors and extensors of runners when compared with a placebo group.Although, for an angular velocity of 60º/s, in both groups (KT and

4 Figure 1 -
Figure 1 -Flow diagram of the study (KT = Kinesio tape).Procedure running training lasted approximately 60 minutes, three times a week on alternate days (Monday, Wednesday and Friday), and included: interval training (sprints of 800, 1000, 400 and 500 m, interspersed with walks), strength/resistance training (with a protocol with educational exercises for running), and continuous or volume training (distances between 5 and 12 km) with each day of the week being a specific training, using as training load the percentage that was achieved by the participants in the Léger test 18 or in the 20-meter running test, a field test to check the cardiorespiratory fitness of participants.The running workouts included initial stretches lasting 5 to 10 minutes for the main muscle groups worked (such as quadriceps, hamstrings, hip, shoulder and trunk adductors and abductors), 5-minute warmups (global mobility exercises and sprints -short and light), total running times of 40 to 45 minutes, and final 5-minute stretches of the main muscle groups worked (such as quadriceps, hamstrings, hip adductors and abductors).Continuous training intensities (subjectively controlled by the Borg scale) were 80%, progressing to 100% of maximum speed, with distances between 5 and 12 km.In the interval training, they ranged from 100 to 115% in the 800 m and 1000 m distances, while in the 400 m and 500 m training the intensities were 105%, progressing to 120%, with stimuli from 4 to 10 shots per training and with walking rest.Strength/endurance training consisted of specific educational exercises for running, for the development of strength and power, where it was possible to identify faulty movements, and thus develop strategies to improve them, and consequently improve the economy and performance of the race.This training used body weight as resistance, alternating the strengthening of upper and lower limbs and trunk -5-8 exercises were performed, of 4-5 series, lasting 20 seconds each series, seeking the maximum number of repetitions in this interval of duration time, with a rest of 60 to 90 seconds.

5 , 6 , 11
The assessment was performed in concentric/concentric mode and the knee ranged from 0° to 90° to test the flexors, and from 90° to 0° to test the right knee extensors.5,6,11Before testing the dynamometer, the device was properly calibrated and ready to store participant data.The assessment was performed with the participant sitting and stabilized in the chair with hip flexion of 85°, with a strap positioned horizontally in the pelvic region and two straps crossed in front of the trunk, in the thoracic region, while another strap stabilized the thigh of the lower limb contralateral to the assessed limb.5,11The equipment rotation axis was aligned parallel to the axis of the evaluated knee joint (lateral epicondyle), and the lower limb was fixed to the lever arm of the dynamometer, with the support pad two centimeters from the heel.5,11The participant had a brief familiarization with the equipment in relation to strength and range of motion after being properly instructed by the evaluator on the proper execution of the test.They were verbally encouraged and given visual feedback on the monitor screen about the test.The same protocol was repeated after 30 seconds of recovery for the second test speed.11 The evaluations were carried out in four moments: two initial evaluations, to verify the acute effect of the elastic bandage without tension (moment 1: without KT; moment 2: with KT, but without voltage applied to Stocco MR et al.Fisioter Mov.2023;36:e36104 6 the KT); two final evaluations, to verify the chronic effect of eight weeks and consequently eight KT applications (moment 3: without KT; moment 4: with KT, with or without tension according to randomization).Intervention KT was applied only to the rectus femoris muscle of the dominant lower limb.The skin was free of moisturizing lotions or oils, hairless and cleansed with alcohol and cotton wool prior to KT application.When removing the protective paper from the KT adhesive,
Data normality was verified by the Shapiro-Wilk test.The homogeneity of variances was determined by Levene's test.To verify whether the two groups showed preintervention differences, Student's t test for independent samples or the Mann-Whitney U test was used.Pearson's χ 2 test was used for gender comparison.For comparison between groups, analysis of variance (ANOVA) was used mixed with two factors and repeated measures, with post hoc Bonferroni test.Effect sizes were calculated using Cohen's d, which were considered small (0.20), medium (0.50) or large (0.80).Intent-to-treat analysis was used, including all randomized participants (missing postintervention data were imputed to baseline data).For all tests, the significance level was 95% (p < 0.05).Analyzes were processed in the SPSS 20.0 program (Chicago, IL, USA), except for effect size calculations (Cohen's d), which were processed in the G Power 3.1 program (Franz Faul, Universita Ä Kiel, Germany).
placebo) there was a statistically significant difference in the comparison between moments 4 and 2 for knee flexors; and in the placebo group, between moments 4 and 2 and moments 4 and 3, for knee extensors.These effects can be attributed to the effect of time and training and not the presence of KT.Future studies involving different populations, in order to verify the chronic effect of KT application, are still necessary.Currently, few systematic reviews with and without meta-analysis have been published involving muscle strength outcomes and KT, and none of them exclusively included athletes.1,2,27 Regardless of the population, there is still no consensus on the influence of KT on muscle strength, however, the methodological quality of the studies currently found in the literature on the subject is still questionable and except for Koç et al., 13 all others found only assess the acute effect of KT and include only one application of the tape.1-3,6,27 We can consider as limitations of this study the number of participants, the angular velocities used, and the intervention time.We observed that the 90º/s angular velocity did not obtain any positive result in relation to strength gain, and that the 60º/s velocity showed positive results.These favorable results for muscle strength gain can be attributed to the effect of time and training, as both flexors (which did not receive intervention) and knee extensors (which received intervention) showed positive results in relation to strength gain.If an angular velocity of 30º/s were used in the evaluations and both lower limbs (those that did not receive any intervention) were evaluated, we would certainly have different results and perhaps favorable to muscle strength gain.Based on conflicting results and methodological limitations in the current literature, additional studies using more rigorous methodology may lead to further clarification on the influence of KT on muscle strength and come to fill in the gaps left by the limitations of this study.However, to date, we know that KT has not been able to significantly alter runners' muscle strength and we cannot extrapolate these findings to athletes in other sports or in conditions other than healthy individuals.
In view of the contradictory results reported in the literature and the emergence of new studies in recent years, in an attempt to resolve the doubts that still exist in the literature about the application of KT in relation to 10 facilitates increased muscle strength in athletes 6,9,10or not.11-16Thesefindings can be explained by the variable methodological quality and small samples, usually of convenience, of the primary studies, which limits the strength of the results of current research on the subject.(após8semanas);(4)com KT e com tensão (pós-protocolo 8 semanas).Comparações inter e intragrupos foram feitas.O nível de significância adotado foi de 95% (p < 0,05).Resultados: Não houve diferenças signi-ficativas na FM entre os grupos em nenhum dos momentos avaliados.Houve diferença estatisticamente significante na FM (60º/s) em ambos os grupos (KT e placebo, quando comparados os momentos 4 e 2 para flexores de joelho, e no grupo placebo entre os momentos 4 e 2 e os momentos 4 e 3 para extensores de joelho.Conclusão: O protocolo de tensão progressiva de KT não foi capaz de intervir no ganho de FM de flexores e extensores de joelho de corredores em comparações inter e intragrupos.Palavras-chave: Atletas.Ensaio clínico.Força muscular.Torque.Stocco MR et al.Fisioter Mov.2023;36:e36104 3MethodsStudy designThis is a randomized controlled clinical trial that included 52 runners who met the eligibility criteria: aged between 18 and 60 years; to be physically able to participate in the experimental study; to be completely independent in performing basic activities of daily living; not present physical, hearing or visual impairment that prevents the performance of the exams or the use of prostheses or orthopedic orthotics; no history of knee, ankle, or hip injuries; no allergies to elastic bandages;

Table 1 -
Baseline characteristics of participants

Table 2 -
Intra-group and between-group comparisons for isokinetic muscular strength (in Nm) Choi and Lee 5 in their study whose objective was to determine the effects of the direction of application of the kinesiological tape on the strength of the fatigued quadriceps muscles that included 15 athletes, concluded that the application of the KT can improve Stocco MR et al.Fisioter Mov.2023;36:e36104 10