Effect of plantar skin resistance on sprint, balance, and jump performance in young elite football players

MURAT BİLGİN1, SERAP ÇOLAK2, MURAT SON2, DAMLA ERCAN KÖSE1

1Department of Physical Education, Istanbul Technical University, Istanbul, Turkey; 2Faculty of Sports Sciences, Kocaeli University, Kocaeli, Turkey.

Summary. Background. This study aimed to investigate the relationship between plantar skin resistance and performance parameters of football players. Methods. A total of twenty-one football players participated in the study. Ten participants were categorized into FSR-A (Foot Skin Resistance-A: below-average foot skin resistance, 17.40±0.51 years), and eleven participants were categorized into FSR-B (Foot Skin Resistance-B: above-average foot skin resistance, 17.55±0.68 years), forming two groups. Plantar skin resistance level measurements were made by fixing the electrodes to the plantar region of the foot with a multimeter instrument called Digital Multimeter (DT-890DL). Anthropometric measurements of the participants, balance measurements, speed measurements and vertical jump measurements were made. Results. A significant difference was found in 30-meter sprint performance in favor of the group with below foot skin resistance (p=0.03*) compared to the group with above foot skin resistance (p=0.77). However, no significant differences were observed in balance right, balance left, balance double, and CMJ (Countermovement jump) performance between the two groups. Conclusions. This research showed that simple parameters such as lower foot skin resistance can indirectly affect the 30-meter sprint performance of the athletes. According to these results, coaches should consider that specific measurements such as skin resistance levels can be effective in physical capacity assessments and training planning of athletes.

Key words. Skin resistance, football, performance.

Effetto della resistenza cutanea plantare sulla velocità, sull’equilibrio e sulla prestazione di salto nei giovani calciatori d’élite

Riassunto. Background. Questo studio ha avuto l’obiettivo di indagare la relazione tra la resistenza cutanea plantare e i parametri di performance nei calciatori. Metodi. Ventuno calciatori hanno partecipato allo studio. Dieci di essi sono stati assegnati al gruppo FSR-A (Foot Skin Resistance-A: resistenza cutanea plantare inferiore alla media; 17,40±0,51 anni) e undici al gruppo FSR-B (Foot Skin Resistance-B: resistenza cutanea plantare superiore alla media; 17,55±0,68 anni). Il livello di resistenza cutanea plantare è stato misurato fissando gli elettrodi alla regione plantare del piede mediante un multimetro digitale (Digital Multimeter, DT-890DL). Sono state inoltre effettuate misurazioni antropometriche, valutazioni dell’equilibrio, test di velocità e misurazioni del salto verticale. Risultati. È emersa una differenza significativa nella performance dello sprint sui 30 metri a favore del gruppo con resistenza cutanea plantare inferiore (p=0,03*) rispetto al gruppo con resistenza superiore (p=0,77). Tuttavia, non sono state riscontrate differenze significative tra i due gruppi nelle misurazioni dell’equilibrio destro, sinistro e bipodalico, né nella performance del CMJ (salto contro-movimento). Conclusioni. La presente ricerca mostra che parametri semplici, come una minore resistenza cutanea plantare, possono influenzare indirettamente la performance nello sprint sui 30 metri. Sulla base di tali risultati, gli allenatori dovrebbero considerare che misurazioni specifiche, come i livelli di resistenza cutanea, possono risultare utili nella valutazione della capacità fisica e nella pianificazione dell’allenamento degli atleti.

Parole chiave. Resistenza cutanea, calcio, performance.

Introduction

The concept of skin resistance (SR), which has been employed since the 1930s to identify pathological conditions, is defined as the resistance to the passage of an electric current and reflects the activity of the sympathetic nervous system1. The SR response or skin resistance level (SRL) is expressed as a component of alternating current and direct current changes in electrodermal activity, respectively, and both terms are commonly used as indices in the study of autonomic nervous system function2.

From a physiological perspective, the skin serves as the first interface that transmits signals from the tissues to the central nervous system and the normal resistance values of human skin tissue range between 1 and 100 (Ω)3.

During standing, the plantar region, as the first area to contact the ground, plays an important role in providing sensory input through pressure and proprioceptive signals4. The skin of the plantar region of the foot contains numerous mechanoreceptors sensitive to joint pressure and tension, and blood vessels, sweat gland activity, and interstitial fluid production are maintained under normal physiological conditions for the foot5. In the study, plantar skin resistance values of the dominant foot were lower than those of the non-dominant foot. This finding was attributed to greater sweat gland activity, vascularization, and electrolyte concentration in the dominant leg6.

Team sport athletes are required to integrate multiple physical components to optimize their performance during training and competition7. Soccer is a sport in which not only physiological and technical attributes but also tactical and strategic elements play a prominent role8,9.

Variables such as cardiorespiratory capacity, muscular strength, power, speed, agility, coordination, and balance are increasingly recognized as significant determinants in athletes’ performance10. During a match, players typically change activities every ~5 seconds, engaging in varied actions such as jogging, sprinting, turning, dribbling, shooting, tackling, and jumping; also players cover approximately 10-13 km of which 185-190 m may be performed at maximal sprinting velocity11,12. The use of relative measurements (normalized to body mass) is recommended when comparing strength outcomes with sprint and countermovement jump (CMJ) performance13.

Balance, sprint, CMJ and foot skin resistance parameters can affect athletic performance in football. In this study, these parameters were evaluated specifically within the context of football.

Whether skin resistance has an impact on performance parameters is not fully understood. There are few studies5,6 on the the relationship between skin resistance and performance outcomes. This study was designed to examine whether skin resistance can serve as a potential indicator of performance.

We hypothesized that lower skin resistance results would be positive effects on 30-meter sprint, vertical jump, and balance due to sympathetic nerve activation responses in the sole of the foot. This study aimed to investigate whether there is a corellation between skin resistance and the countermovement jump, balance, 30-meter sprint results obtained with football players.

Materials and methods

Participants

A total of twenty-two football players participated in the study. One athlete was excluded from the study, resulting in the evaluation of a total of twenty-one participants. This study was designed as a cross-sectional, observational, two-group comparative study.

Participants were divided into two groups according to their plantar skin resistance levels: ten participants were categorized into FSR-A (Foot Skin Resistance-A: below-average foot skin resistance, 17.40±0.51 years), and eleven participants were categorized into FSR-B (Foot Skin Resistance-B: above-average foot skin resistance, 17.55±0.68 years), forming two groups (figure 1). Table 1 shows physical characteristics of the participants.







The sample size was estimated using the T test category in G Power 3.1.9.7 software [power (1-β)=0.7, effect size=0.56, type-1 error (β)=0.05, number of groups=2]. Before the initiation of the study, the subjects were asked to fill out a questionnaire to determine whether they had any musculoskeletal pain, discomfort, or known injury in their lower extremities. According to detailed health questionnaire and a clinical examination, all athletes were confirmed to be free of cardiovascular disease. Twenty-one elite football players from a top ranking team in the Turkish First League volunteered to participate in this study. Each player was informed of the testing procedures, potential benefits, and associated risks and written informed consent was obtained from each participant. This study was conducted according to the guidelines of the Declaration of Helsinki and was approved by Kocaeli University Non-Interventional Clinical Research Ethics Committee on 30.11.2020 with the decision number 2020/20.08 and project number 2020/11.

Study design

All measurements were made in the same environment following a standardized warm-up. The nature of the procedure was explained to the subjects. Assessments were carried out in a temperature-controlled room with the temperature maintained at temperature 23±1 °C, humidity 45–50. Anthropometric and balance measurements of the participants were performed on the same day. Participants with a recent lower extremity injury were excluded from the study. All approvals were obtained, and the measurements of the participants were made within the planned program. Anthropometric parameters, skin resistance level, balance performance, vertical jump and 30-meter sprint test measurements were performed on each participant (figure 1). After the anthropometric measurements, the balance levels of the participants were measured. Skin resistance, countermovement jump, and 30-meter sprint measurements were performed 24 hours later. The data were collected at Kocaeli Vinsan Stadium.

Measurement of foot sole skin resistance level

Foot sole skin resistance level measurements were made by fixing the electrodes to the plantar region of the foot with a Digital Multimeter (DT-890DL) (figure 2).




All measurements were performed by the same trained operator under standardized environmental conditions (temperature 23±1 °C, humidity 45-50 %). Before data collection, preliminary trials were conducted to ensure measurement consistency. For this purpose, three consecutive readings were taken from each participant under identical conditions, and the obtained values were checked for internal consistency to confirm the stability of the measurements. Previous experimental research has demonstrated acceptable reliability (ICC=0.76–0.86) for single-operator electrodermal measurement systems operating on the same principle of skin resistance to electrical current14. These findings support the consistency of such devices when standardized protocols and single-operator measurements are applied. Participants were asked to clean and dry the soles of their feet before participating in the measurement. After the electrodes with conductive gel were placed from the heel to the metatarsal heads, the measurement was recorded as kilo ohms when the value was fixed while standing on one foot while connected to the dominant foot5. In the results that changed during the measurement, the value that remained constant after 10 seconds was accepted.

Anthropometric measurements

Basic anthropometric data such as height and body weight of all participants were collected. Foot lengths were measured as the distance between the calcaneare and the acropodion when the participants were in the standing anatomical position. Lower extremity lengths were measured as the distance between the anterior superior iliac spine and the medial malleolus while the participants were standing. The intermalleolar diameter of the foot was measured with participants in a 90-degree sitting position. The distance between the lateral malleolus process of the fibula and the medial maleous of the tibia was measured.

Performance measurements

Balance measurements

Balance measurements of the participants were performed using an Easy-Tech balance measurement device. Before the balance measurements, participants were provided with the necessary instructions to the participants and then they were asked to stand on the balance beam. The research group was tested following a standardized warm-up consisting of a 5-minute low-intensity run in light sportswear and stretching exercises. Each measurement was performed in three trials of 30 seconds each, first as the right and left single foot, and then as both feet. Since each numerical increase in the measurement is an indicator of the balance deviation, higher scores reflect lower balance performance.

Countermovement jump Test

Countermovement jump (CMJ) performance was assessed using a jump meter. A belt connected to the device was secured at the participant’s abdominal level and the participants were asked to stand on the exercise mat. Participants stood with their feet shoulder-width apart and arms free. When ready, they performed a countermovement jump by flexing the knees and hips; meanwhile, the arms are first brought back and then brought closer to the body, followed by an explosive upward jump, and then the feet are placed on the exercise mat. Jump height was recorded in centimeters.

30-meter Sprint Test

The 30 m sprint test was performed at maximal effort within the designated area and was performed using the Microgate brand photocell device. Sprint time was recorded in seconds.

Data analysis

Statistical evaluations of the research were made in the SPSS 29.0 package program. Normal distribution tests were performed on the data obtained, two sample T-test based on the average of two independent populations was used for the variables conforming to the normal distribution, Correlation analysis was performed to determine the relationship between the variables. Descriptive statistics of the variables were also calculated. The data were analyzed at 95% confidence interval and 0.05 significance level.

Results

Table 1 shows the descriptive statistics of the characteristics of the Foot skin resistance-A (FSR-A) and Foot skin resistance-B (FSR-B) football player groups. The descriptive statistics of participants divided into two groups based on foot skin resistance levels: FSR-A (below-average) and FSR-B (above-average). The groups were comparable in terms of age, with mean ages of 17.40 ± 0.52 years for FSR-A and 17.55 ± 0.69 years for FSR-B.

Foot number and intermalleolar diameter were similar across groups, foot skin resistance values clearly differed, validating the grouping: FSR-A showed a mean resistance of 43.78 ± 6.01 kΩ, whereas FSR-B averaged 59.70 ± 7.33 kΩ (table 1).

Table 2 presents the correlation between foot skin resistance and various performance measures including balance (right, left, double leg stance), 30-meter sprint, and countermovement jump in both FSR-A and FSR-B groups.




According to the statistical findings, a significant difference was observed only in the performance of the 30-meter sprint (p=0.03). This difference was identified in the FSR-A football group, characterized by below average foot skin resistance. In the FSR-B group with above average foot skin resistance, no significant differences were observed in the 30-meter sprint (p=0.77), countermovement jump (p=0.65) and balance tests (balance right (p=0.97), balance left (p=0.98), balance double (p=0.39)). In the FSR-A group, no statistically significant results were observed except for the 30-meter sprint test.

Effect size analyses indicated trivial to small differences for balance tests (d=0.02–0.25) and a small effect for the 30-meter sprint (d=0.20), favoring the low-resistance group. A large effect was observed for CMJ (d=1.09), although this difference was not statistically significant (p=.65). The large effect size despite non-significant results may be attributed to the small sample size and the high variability in jump performance.

Discussion

Football is one of the most popular sports globally. However, considerable uncertainty and debate persist regarding its physical demands. This is primarily due to the frequent prioritization of skill development over physical fitness, the limitations of conventional training approaches and the inherent challenges associated with scientifically investigating football15. In this context, the present study provides a novel and physiologically oriented perspective for evaluating athletic performance in football players. Although football performance has traditionally been analyzed through technical and tactical dimensions, the physiological and sensory mechanisms underlying on-field performance remain insufficiently explored. During a 90-minute match, players execute numerous explosive and high-intensity movements, such as jumping, shooting, tackling, turning, and sprinting11,16-19 while constantly adjusting pace, maintaining balance, and sustaining ball control under defensive pressure through rapid neuromuscular responses. These multidimensional demands require the integration of motor control, sensory feedback, and fatigue management, yet current training practices often prioritize skill acquisition over physiological readiness. By examining the relationship between plantar skin resistance and performance parameters, this study aims to bridge this gap and provide insight into how peripheral physiological responses may influence sport-specific performance. Football is globally practiced by men and women across all ages and levels of expertise21, making such findings potentially relevant for both professional and developmental contexts.

In this study, we assessed the performance levels of athletes from the same football team, who were matched for age, body weight, and height, in relation to their foot skin resistance values The central research question addressed was: does lower or higher foot skin resistance in football players lead to significant differences in performance outcomes? In a study investigating the effects of sole skin resistance on proprioceptive sensation and balance, it was reported that there was no statistically significant difference between the mean values of the dominant and non-dominant footpads skin resistance levels. However, the same study also noted that the footpad skin resistance values of the control group were higher than the foot skin resistance values of the experimental group, and the difference between them was statistically significant6. Based on these findings, in the present study, foot skin resistance measurements were taken from the dominant foot.

Several studies have examined the influence of regular exercise habits on skin resistance, suggesting that physically active individuals typically demonstrate lower resistance levels than their sedentary counterparts. This phenomenon is largely attributed to increased sympathetic nervous system activity during exercise, which enhances sweat gland responsiveness and thereby reduces skin resistance22. In line with this, the negative correlation observed in the present study between skin resistance and performance level supports the notion that higher sympathetic activation facilitates both thermoregulatory efficiency and neuromuscular readiness23. These results are consistent with the idea that regular exercise promotes adaptations in autonomic function, leading to improved peripheral responsiveness. Moreover, the importance of sweat evaporation in thermoregulation becomes particularly evident during strenuous physical activity or heat exposure, where impaired sweating capacity can compromise performance and homeostasis24. From a biomechanical standpoint, the plantar surface – being the first point of contact with the ground – plays a crucial role in providing sensory feedback related to pressure and proprioception4. The motor system adjusts movement patterns according to the mechanical load detected by the foot to minimize stress and maintain stability25,26. Collectively, these mechanisms may explain why athletes with lower plantar skin resistance exhibited superior sprint performance in the present study. This research was conducted with the awareness that the plantar surface is a key focus of sensory-motor integration, and that future studies in this area may offer more meaningful and effective contributions to the field of football performance and training. In our study, statistically significant result was observed only in the 30-meter sprint test among football players with lower foot skin resistance values (p <0.05). In previous research investigating sprint performance, the initial 5–10 meters were identified as the acceleration phase, while the 30-meter distance was considered a key indicator of maximal sprinting speed capacity27. The significance observed in our findings may be attributed to the longer ground contact time of the foot associated with the 30-meter sprint compared to balance tests and countermovement jumps (CMJ). This suggests that foot skin resistance may have limited impact on short-duration activities but could play a more influential role in performance tasks involving prolonged foot-ground interaction. Future studies should consider evaluating foot skin resistance across different sports disciplines that involve varying ground contact durations in order to obtain clearer and more generalizable results. In a study investigating the effects of plantar pressure on sprint performance, it was reported that load transfers across the plantar surface during sprinting – such as medial, lateral, and posterior shifts could either impair or enhance sprint performance28. Additonally, it has been suggested that foot pressure distribution may influence athletic performance in soccer players29 which in turn could have an effect on plantar skin resistance. In our study, the overall resistance of the plantar surface was assessed as a whole. This highlights the potential value of evaluating regional variations in plantar skin resistance for a more nuanced interpretation of the findings. Therefore, future studies should consider measuring and analyzing resistance in specific regions of the plantar surface separately, particularly during exercises of varying durations. The sympathoadrenal system plays a critical role during exercise by contributing to cardiovascular regulation, fuel mobilization, and hormonal secretion. Norepinephrine, in particular, helps regulate blood flow and optimizes metabolic processes, which can result in physiological responses such as sweating and thermoregulation at the skin surface30. Increased sympathetic activity and norepinephrine release during dynamic exercises may lead to changes in foot skin resistance. The plantar surface of the foot is essential in providing the central nervous system with pressure and proprioceptive feedback. To maintain postural balance during standing, the motor system generates appropriate based on the mechanical load perceived through the foot – an especially important function for football players who remain physically active throughout the match23.

These findings may offer valuable insights for coaches, as monitoring plantar skin resistance could help assess physical readiness, contribute to the development of sport-specific conditioning strategies, and potentially enhance athletic performance.

Limitations of the study

This study has several limitations that should be acknowledged. First, plantar skin resistance measurements were taken across the entire plantar surface, without distinguishing between specific regions (forefoot, midfoot, and heel). This approach may obscure the potential differential effects of regional plantar pressure and sensory feedback on performance. Second, the sample was limited to players from a single football team, restricting the generalizability of the findings across age groups, sexes, skill levels, and competitive contexts. Third, the digital multimeter used, while calibrated and verified through repeated readings, was not specifically designed for physiological research. Nevertheless, previous studies with similar electrodermal systems have shown acceptable reliability for single-operator measurements under standardized conditions14.

Conclusions

The study demonstrated a statistically significant improvement in 30-meter sprint performance in football players with lower plantar skin resistance. No significant differences were observed in vertical jump or balance tests, indicating that plantar skin resistance primarily affects activities involving sustained foot-ground contact rather than short-duration or postural tasks. The observed effect on the 30-meter sprint may be explained by the extended ground contact time and the continuous application of plantar pressure during this distance, which likely enhances sensory feedback and neuromuscular efficiency. Given the limited literature on the relationship between plantar skin resistance and athletic performance, future studies should consider region-specific measurements of plantar resistance such as forefoot, midfoot, and heel – to determine whether localized variations correlate more strongly with sprinting, jumping, or balance outcomes. Additionally, examining performance tasks of varying durations could clarify the temporal thresholds at which plantar skin resistance meaningfully influences performance.

Future research should address these limitations by employing larger and more diverse samples, incorporating region-specific plantar resistance assessments, conducting longitudinal studies, and examining different football movements and sports disciplines. Additionally, integrating neurophysiological measures (e.g., EMG, postural sway analysis) could provide further insight into the mechanisms linking plantar resistance with athletic performance. Investigating the potential interactions between plantar resistance, footwear or insole interventions, and performance outcomes may also yield valuable practical applications for performance optimization and injury prevention.

Conflicts of interest. The authors declare that there is no conflict of interest.

Authors’ contributions. Conception – design of the manuscript: MB, SC; Data acquistion: MB, SC, MS, DEK; Data analyses: MB, SC, MS, DEK; Interpretation of the Data: MB, SC, MS, DEK. All authors worked on finishing the manuscript.

Acknowledgments. The authors thank all the volunteers for their participation in the study.

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