The Interrelation of Clarke’s Angle with Body Composition and Lower Extremity Explosive Muscle Strength in School-going Adolescents: A Cross-sectional Study

1. INTRODUCTION

Adolescence is a critical period with many important physiological and behavioral changes, including alterations in body composition, changes in fitness attitudes, physical activity, and sedentary behavior [1]. The foot posture of children varies from adolescence to adulthood due to periodical changes in growth and musculoskeletal maturation [2, 3].

However, with gradual growth and development, plantar fat gradually disappears, the valgus angle decreases, and the longitudinal and transverse arches of the foot become prominent [4]. The process of progressive development of the foot arch ends mostly between 10 and 13 years of age and is characterized by specificity in comparison to overall somatic development [5]. In the most common foot disorders, i.e., flat foot (pes planus, a biomechanical change), there are significant changes to the talocalcaneal and talonavicular joints, which increases the risk of foot pain, knee pain, and poor exercise performance [6, 7] and puts an individual at risk of injury [8].

It has been proposed that flatfoot is associated with body composition [9, 10]. More distinctively, the amount of muscle mass (appendicular lean mass index) [11] may be associated with the development of flatfoot. During any closed kinetic chain activity, the foot serves as a terminal part of the chain, and any deviation from normal foot posture may affect the motor abilities of the lower extremities, which may indirectly influence physical performance related to sports and leisure activities. Fundamentally, physical performance has been regarded as a useful and powerful marker of health in adolescence [12]. For that reason, it is important to investigate the degree of flatfoot and its connection with body composition and lower extremity physical performance in adolescence. Therefore, the primary purpose of this study was to characterize foot posture in school-going adolescents aged 11-17 years and investigate the relationship of foot posture with BMI and lower extremity muscular explosive strength.

2. MATERIALS AND METHODS

2.2. Testing Protocol

All the measurements and tests were carried out in the morning hours during the physical education classes. The test protocol in all the schools was the same, and the measurements were carried out by the same group of researchers to avoid any measurement error. The test was carried out in random order to avoid the carryover effect of one testing method over the other. Before the test measurements were started, verbal instructions and demonstrations were given to all the participants regarding the testing procedures. The test procedure was subsequently conducted in a 3-part system.

2.2.1. Anthropometric Measurements

Weight: It was measured without shoes with an electronic weighing scale to the nearest 0.1 kg.

Height: Height was measured using a height meter, without shoes or arms hanging loosely by the side of the body, and the height meter was pulled on the top of the head with enough impact to feel bony resistance; the reading was then taken in centimeters.

Body Mass Index (BMI): BMI was calculated via the Quetelet index [14].

2.2.2. Measurement of pes Planus

2.2.2.1. Clarke Angle (CA)

For CA measurement, a static footprint was obtained. Each student was asked to step both feet onto a steel tray with water-soluble ink and ask them to press firmly over the ink pad; then, they were asked to step forward, placing their right foot onto a white sheet and, similarly, his/her left foot. They were asked to stand stable in a relaxed bipedal stance position with equal weight on both feet. If the footprint was not clear because of an inadequate amount of ink, the footprint was discarded, and the procedure was repeated to obtain a good footprint. The

footprints were then allowed to dry for some time. The CA was calculated via a marker pen, ruler, and protractor marked at one-degree intervals, and the angle between the medial tangential line that connects the medial edges of the first metatarsal head and the heel and the second line that connects the first metatarsal head and the medial longitudinal arch concavity was calculated [15].

2.2.3. Physical Performance Assessment

2.2.3.1. Standing Long Jump Test

A line was drawn on a ground hard surface that served as the starting line. The student had to stand behind the line marked on the ground with feet slightly apart. The student was asked to jump horizontally as far as possible, landing on both feet. Each student was given 3 trials, and the distance of the best jump was measured, to the nearest 1 cm, from the line to the point where the heel closest to the starting line landed. The length of the jump was determined via a tape measure. If the subject fell backward, the distance where the body part closest to the starting line touched the ground was measured as the jump length [16].

3. RESULTS

4. DISCUSSION

There is no clear specific clinical or radiologically accepted universal definition of flatfoot, and in simpler terms, it is a condition in which the longitudinal arch of the foot collapses, and only 4% of cases persist after 10 years of age in children [17]. Flexible flatfoot is usually asymptomatic. However, if it is associated with a short Achilles tendon, it can give rise to pain and functional disability [18]. This impairment often goes unnoticed, and in the time ahead, it may affect sports and recreational activity performance among adolescents. Therefore, the present study aimed to determine which type of association may occur between flexible flatfoot and body composition and lower limb explosive muscular strength among school-going adolescents. The major outcome of the present study was that an insignificant statistical association existed between pes planus and the Standing Long Jump Test (SLJT), irrespective of body composition. These results have revealed that flat feet do not have any negative influence on horizontal jumping ability in this studied population and, second, counter parental clinical concerns regarding flat feet.

Barabas and Malina et al. specified that during the period of childhood, the average Standing Long Jump (SLJ) performance increases linearly with age in both sexes until the age of 12 in girls and 13 in boys [19, 20]. In the present study, we aimed to investigate the correlation of flatfoot with lower extremity explosive muscle strength in general. Biomechanically, the SLJ movement system has two main phases: preparation (arms swing and flexion of hips, knees, and ankles) and action (take-off, flight, landing, and standing recovery) [20, 21]. Electrophysiological assessments with electromyography, EMG, or motion capture technology to assess muscle activation during each phase of a long jump were not performed in the present study. Therefore, the distinct effect of Pes planus on horizontal jumping performance cannot be explained well in terms of biomechanical characteristics, which could have enhanced the depth of the analysis in the study.

Numerous authors have clearly described the gradual increase in jump height performance from childhood to adolescence [22-24]. The standing long jump test is commonly used in practice to assess the explosive power of the lower extremity, and the literature has shown varied results across different studies. Ho M et al. reported that flat-footed basketball players produced a lower horizontal ground reaction force and lower hip angular velocity than did normal-arched players in standing long jump test performance, and this characteristic lower extremity biomechanical variance suggests that flat-footed individuals must work hard to achieve the same performance [23]. In another study by Sagat et al., test performance in children with flat feet was below the standard in a few physical performance tasks, and the same participants presented significantly poorer results in bilateral and unilateral SLJT [24]. The current study also revealed a non-significant statistical association between the standing long jump test and Clarke’s angle measures. The occurrence of flat feet can be multifactorial and can be present from birth or develop later in life; most of these conditions are physiological or pathological causes associated with laxity of the ligament, midfoot laxity, posterior tibial tendon insufficiency, and tarsal coalitions. Most often, flatfoot remains asymptomatic, and clinicians consider it an essentially normal condition. Variability in clinical assessment techniques and consideration of physical and biomechanical factors in the evaluation of flat feet across various studies have revealed conflicting results regarding the associations of pes planus with lower extremity explosive muscle test performance. Therefore, a clearer explanation of the influence of flatfoot on horizontal jumping performance is difficult without a detailed analysis of the characterization of ankle and foot biomechanics.

With respect to vertical jumping ability, most studies have focused on determining the effect of the pes planus on vertical jump height across different age groups, i.e., children to adulthood along with athletes to nonathlete participants, and the results have revealed a non-significant association between jump height and the existence of the pes planus. Alexandrovic et al., in a pilot study in which the vertical jump height of adolescent individuals was related to the degree of pes planus, reported no significant differences [25]. Thus, the vertical jump ability is clearly unlinked with the degree of pes planus.

Another additional finding of a non-significant correlation between body composition and a flat foot stood as a cofounding result in our study, and the pattern appeared to be like that of the study by Daneshmandi et al., in which the researchers reported no meaningful association between BMI and a flat foot [26]. In contrast, Chen et al. and Pourghasem et al. reported a strong positive correlation between increased BMI and flatfoot in children [27, 28]. Another study in South India by Reddy and Kishve investigated 300 medical students in the 17-23 year age group and reported a flat foot to be associated with BMI and weight and to have a weak relationship with foot length and height [29]. This variability in the association of BMI with flatfoot may be due to factors related to the developmental and biomechanical characteristics of the lower extremity, which may further affect the usual development of the foot structure. With the correlational analysis of BMI and horizontal jumping ability tested with SLJT, we found a non-significant relationship, and the results have been found to be in line with those of a study by Kwiecinski et al., in which the association between BMI and performance ability tested with the standing long jump was not significantly linear in either sex [30].

The demographic characteristics of the 150 school-aged adolescents in our study included a median BMI of 17.1kg/m² for males and 17.0kg/m² for females, indicating the participants to have adequate nutrition and age-appropriate physical growth. This finding was consistent, although marginally like that reported by Khadilkar et al. [31]. Furthermore, genetic and environmental factors differ across geographical areas and ethnicities [32], and because of these factorial variations, it is difficult to generalize the anthropometric findings. The analysis of the minimum-maximum degree of flat foot measured with Clarke’s Angle (CA) revealed the right and left angle ranges to be between 12-60° (IQR 9.75) and 10-55° (IQR 9.00) in male participants, whereas among females, they were 27-57° (IQR 10.00) and 26-55° (IOR 8.25), respectively, indicating considerable variability in the pes planus angle among the studied population. With respect to Clarke’s angle, the literature suggests CA 42°–54° (normal), 35°-41° mild flatfoot, 30°–34.9° (moderate), < 30° (severe), and > 54° (high arched) to be the reference value criteria for adolescents [17, 33-35].

Jumping is an important motor skill, and its performance depends entirely on physical health-related fitness, body composition, muscular flexibility and strength, speed, agility, and many other factors. Any sort of jumping requires a definite explosive muscle strength of the lower extremity, and an individual’s performance may vary depending on several factors in relation to anthropometry and physiological and biomechanical characteristics [36]. However, the findings of the present study have shown that the pes planus does not negatively influence horizontal jumping ability. Ultimately, these findings show that for physical educators and sports coaches to fully unlock the potential of those with flat feet, they must take a proactive approach to encourage all children and adolescents to participate in sports activities. Most importantly, the findings of the current study have supported the practical utility of Clarke’s angle measurement to thoroughly screen and characterize pes planus during the developmental transition age period from childhood to adolescence. Early identification and evaluation of pes planus in school-going children by health care professionals, sports coaches, or physical educators are important to prevent the lower extremity biomechanical pattern from being negatively affected and lessen other secondary foot problems associated with flat feet. Furthermore, with the knowledge of foot posture, adolescent readiness for sport and leisure activity participation can be well planned in a more integrated and interdependent approach by physical educators and sports coaches.

There are many studies pertaining to flat feet in children and adolescents, with conflicting evidence indicating the associations of flat feet with sports- and recreational-specific physical performance. Previous studies have shown that flatfoot in children causes parental anxiety because of concerns that it may develop into a pathological flatfoot later in life [37]. With our study results, we can conclude that flexible flat feet are not a challenging concern related to the required explosive physical strength of the lower extremity in this specific adolescent population, which is essentially a major strength of the current study. However, there have been certain limitations in the present study. First, the study population was confined to two schools, and we considered children with flexible flat feet. Second, we examined the biomechanical activation of the selected muscles during each phase of the horizontal jump test and did not consider the physical, psychological, and environmental influences. Third, by drawing upon a cross-sectional study design, we could not determine the causal relationship between flat feet and the explosive muscle strength of the lower extremities. Given these limitations, the generalizability of the findings to other populations seems to be difficult in terms of a comprehensive understanding. Therefore, future research with a larger sample from a wider geographical region and with more comprehensive biomechanical assessments may help clarify the relationships among flat feet, body composition, and lower extremity physical performance ability. Further longitudinal studies are needed to establish the influence of ankle and foot biomechanical factors on jumping ability to provide greater evidence of their cause-effect relationships.

CONCLUSION

Our study results have indicated that flat feet do not influence horizontal jumping ability. These results counter the adverse effects of flat feet on participation in low- to high-impact sports and leisure activities, which require explosive muscular strength of the lower extremities. However, the study has involved several limitations, including a restricted population scope, a lack of biomechanical analysis, and a cross-sectional design limiting causal inference. Future research with larger, more diverse samples and thorough comprehensive biomechanical assessments could help clarify the relationships among flat feet, body composition, and lower extremity explosive muscular strength. Furthermore, early identification and evaluation of pes planus in school-going children and adolescents by health professionals, sports coaches, and physical educators will assist them in developing and planning a more integrated and interdependent approach toward their readiness for sport and leisure activity participation.

REFERENCES