https://orcid.org/0000-0002-3936-5029
Figures
Abstract
Introduction
The Upper Quarter Y Balance Test (UQYBT) is a validated tool used to assess unilateral upper extremity function in a closed kinetic chain. It evaluates parameters such as mobility, stability, and injury risk, and can inform rehabilitation planning. Normative data have been well established for adolescent and active adult populations in the United States. This study aims to establish normative UQYBT values for healthy adults aged 18–36 years in the Indian subcontinent.
Methods
A total of 190 healthy young adults (95 males and 95 females) aged 18–36 years who met the eligibility criteria were included. Baseline demographic data—age, height, weight, body mass index (BMI), and limb length—were collected. Participants performed the UQ-YBT by reaching in the inferolateral, medial, and superolateral directions using the three-reach box. Average reach distances were calculated for each limb, and composite scores (CS) were normalized using arm length.
Results
Age- and sex-specific reference values were established for both upper extremities and for average bilateral performance. Males demonstrated significantly greater reach distances than females; however, the difference decreased after normalization for limb length. Age-related variations were observed, with participants aged 26–30 years achieving the highest normalized reach scores (p < 0.05).
Citation: Pavithran A, Rajasekar S, Cleland J, Ramkumar V, Hazari A (2025) Normative value of upper extremity Y balance test in healthy subjects aged between 18 and 36 years from South India: A cross-sectional study. PLoS One 20(10): e0335443. https://doi.org/10.1371/journal.pone.0335443
Editor: Mário Espada, SPRINT - Sport Physical Activity and Health Research & Innovation Center, PORTUGAL
Received: July 11, 2025; Accepted: October 10, 2025; Published: October 27, 2025
Copyright: © 2025 Pavithran et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Data Availability: All data have been given in the manuscript and supplementary files.
Funding: The author(s) received no specific funding for this work.
Competing interests: The authors have declared that no competing interests exist.
Introduction
Shoulder pain is the third most common musculoskeletal complaint presenting in primary care [1]. The shoulder’s structural and functional complexity, characterized by a wide range of motion at the expense of joint stability, makes it susceptible to dislocations and overuse injuries [2]. Young adults and adolescents, particularly those engaged in sports, experience a disproportionately high rate of such injuries [3].
Shoulder injuries may result from cumulative low-energy stress (repetitive with gradual onset), high-energy trauma (acute with rapid onset), or a combination of both (repetitive with sudden onset) [4]. These injuries can vary in severity and may lead to functional impairment or absence from sport. Additionally, dysfunction in surrounding structures, such as the cervicothoracic spine, ribs, and muscles controlling scapular movement, can influence glenohumeral mechanics and contribute to shoulder pain [5]. Notably, altered scapular kinematics have been linked to shoulder dysfunction due to their role in coordinating upper limb movement [6].
In recent years, increasing attention has been given to the role of movement quality and neuromuscular control in both injury prevention and rehabilitation. Functional performance tests offer a means of assessing these qualities in a controlled and repeatable manner. These tests are not only useful for identifying current deficits but also serve as screening tools to predict future injury risk in athletic and physically active populations [7]. Among them, the Upper Quarter Y Balance Test (UQ-YBT) has emerged as a reliable and efficient method for evaluating upper extremity function in a closed kinetic chain position [8–10].
The UQ-YBT requires individuals to maintain stability on one upper limb while reaching with the contralateral arm in three directions—medial, inferolateral, and superolateral [11]. Reach distances are recorded and normalized to limb length, allowing for meaningful comparisons across individuals of different body sizes [12]. The test has been used to explore how variables such as sex, age, limb dominance, and training background affect upper limb performance [13,14]. Normative values for the UQ-YBT have been established in Western, adolescent, and athletic populations, but such data remain scarce for South Asian or Indian cohorts [14,15]. Given the anthropometric, cultural, and physical activity differences across populations, localized norms are crucial for accurate assessment. The UQ-YBT is also useful in identifying asymmetries or movement dysfunctions that may not be apparent during routine clinical assessment [15].
However, while reference values for the UQ-YBT exist for certain populations, there is a lack of normative data for young, healthy Indian adults. Such data are essential for clinicians and researchers seeking to interpret performance and identify deviations that may warrant intervention. Establishing such normative values is essential for informed clinical decision-making, particularly in the contexts of sports rehabilitation, injury risk screening, and return-to-play planning. Furthermore, the early detection of asymmetries or functional deficits may help prevent the progression of overuse injuries, especially in overhead athletes. We hypothesized that males would demonstrate greater UQYBT reach distances than females, and performance would vary by age, with young adults in their mid-20s exhibiting peak scores. Therefore, this study aimed to establish normative values for the UQ-YBT in healthy individuals aged 18–36 years in the Indian subcontinent.
Methods
Study design and settings
This cross-sectional observational study was conducted at the Institute of Physiotherapy, Srinivas University, City Campus, Mangaluru, Karnataka, India.
Ethical approval and consent for participation
The ethical approval was obtained from the Institutional Ethics Committee, Institute of Physiotherapy, Srinivas University, City Campus, Mangaluru, Karnataka, India (Approval No. SUIP/PG22/130/2022). All participants provided written informed consent before the data collection. Fig 1 illustrates the study’s flow, showing the number of participants screened, excluded, and included for data analysis.
Sample size
The required sample size was calculated using the formula for estimating a mean:
N = (Zα × σ/ D)² where Zα = 1.96 (for 95% confidence), σ = 21 (pooled standard deviation from prior research) [11], and D = 3 (acceptable margin of error). This yielded an estimated sample size of approximately 188. A final sample size of 190 participants was used.
Eligibility criteria
Participant eligibility was determined through a set of predefined criteria. The inclusion criteria comprised males and females aged between 18 and 36 years who were identified as young, active adults based on the International Physical Activity Questionnaire (IPAQ) [16]. Exclusion criteria included the presence of neck or upper back pain within the past six months, structural spinal deformities such as scoliosis, a history of soft tissue injury or fracture of the upper extremity within the past year, recurrent shoulder dislocations, a history of soft tissue injury or fracture in the lower extremity, low back pain within the previous six months, and any known neurological conditions.
Data collection procedure
Participants were classified based on age, sex, Body Mass Index (BMI), and physical activity level as assessed using the IPAQ. The IPAQ is a validated tool used to measure health-related physical activity levels [16,17]. For analysis, participants were divided into five age-based groups, each with a four-year class interval, except for the last group, which comprised a three-year class interval as per the set upper age eligibility criteria.
To ensure consistency and standardisation, the examiner provided all participants with a detailed explanation of the testing procedure. Additionally, the assessors underwent prior training and practiced administering the Upper Quarter Y Balance Test (UQ-YBT) on several individuals before the commencement of actual data collection.
Participants were familiarized with the testing procedure. Testers underwent training and practiced the Upper Quarter Y Balance Test (UQ-YBT) on multiple individuals before data collection to ensure reliability. Before testing, the length of each upper limb was measured separately from the spinous process of C7 to the tip of the middle finger with the shoulder abducted to 90°. A standardized warm-up, including multidirectional shoulder movements, was completed.
The Y Balance Tool (Functional Movement Systems™) was used to perform the test. This tool features a stance platform with three rods positioned at specific angles forming a “Y” to allow measurement in the medial (MD), inferolateral (IL), and superolateral (SL) directions. Participants assumed a push-up position with feet shoulder-width apart (Fig 2a) and performed four practice attempts on each side. For the actual test, participants reached in the three specified directions using the non-weight-bearing arm while maintaining balance on the opposite arm. The medial direction reach is shown in Fig 2b, the superolateral direction in Fig 2c, and the inferolateral direction in Fig 2d. The reaching arm was not allowed to touch the ground, and the participant had to return to the starting position to complete the movement. Each direction was reached once per trial, and three trials were performed for each arm. A 30-second rest was given between trials to reduce fatigue and ensure consistent performance [18]. Participants then switched sides, performing the same procedure with the opposite arm as the weight-bearing limb. Reach distances were measured in centimetres, and three values per direction were recorded. The average of the three attempts in each direction was used for analysis.
Data normalization and reporting
The data was normalized to limb length as given below:
The study adheres to all strengthening the Reporting of Observational Studies in Epidemiology (STROBE) guidelines and presents the required data accordingly.
Data analysis
Normality of the data was assessed using the Kolmogorov–Smirnov test. As the data were not normally distributed, descriptive statistics are reported as medians with interquartile ranges (IQR). Age-group comparisons were analysed using the Kruskal–Wallis test. The Mann–Whitney U test was used to examine differences between males and females in test scores. Statistical significance was set at p ≤ 0.05.
Results
A total of 190 participants (95 males and 95 females) aged 18–36 years were included. Descriptive demographic characteristics and between-sex comparisons are presented in Table 1. Statistically significant differences were observed between males and females in height, weight, BMI, and upper limb length (p < 0.001). Sex-specific percentile values and curves (10th, 50th, and 90th percentile) is presented in Fig 3.
Raw reach distances
As shown in Table 2, males demonstrated significantly greater absolute reach distances than females across all three directions, medial (MD), superolateral (SL), and inferolateral (IL),as well as higher composite scores (CS). For example, in the dominant arm, median MD reach was 77.5 cm (IQR: X–X) in males versus 70.2 cm (IQR: X–X) in females (p < 0.001). Similar trends were observed for SL and IL directions on both arms.
Normalized reach distances
When reach distances were normalized to limb length (Table 3), males continued to outperform females in most directions. However, the sex difference was attenuated, particularly for the medial direction of the dominant arm, where normalized scores were comparable (p = ns). Composite scores remained significantly higher in males after normalization (p < 0.05).
Age-based differences
The reach performance stratified by age groups is presented in Tables 4 and 5. Participants in the 26–30-year age group generally achieved the highest reach distances in both raw and normalized scores. Statistically significant differences were found across age groups in the superolateral and inferolateral directions (p < 0.05), suggesting an age-related variation in upper extremity dynamic stability and control. Table 6 indicates side-to-side asymmetry values per reach direction.
Discussion
This study aimed to establish normative values for the Upper Quarter Y Balance Test (UQYBT) among healthy adults aged 18–36 years in the Indian subcontinent. To our knowledge, this is among the first studies to generate such region-specific data, addressing a notable gap in the literature on functional assessment in South Asian populations. A key strength of this study lies in its balanced male–female ratio and relatively large sample size, which enhances the reliability of sex-based comparisons. Consistent examiner training and standardized protocols further minimized measurement bias. We hypothesized that males would demonstrate greater UQYBT performance and that scores would vary by age, peaking in mid-adulthood. Our findings supported both assumptions. The study confirmed sex- and age-related differences in UQYBT performance, with males demonstrating significantly greater reach distances. The subgroup analysis for age revealed maximum reach distance in the 22–25 age group among females, and the 26–29 age group among males. These differences likely result from physiological and biomechanical factors. Males typically have greater upper-body strength and power [19], due in part to higher testosterone levels, which promote muscular hypertrophy and neuromuscular efficiency. Enhanced shoulder girdle and trunk strength likely contribute to postural control and dynamic stability in the closed kinetic chain position used during the test. Additionally, better proprioceptive acuity [20] and core stability may support multidirectional reaching, explaining the higher performance observed in males.
Our findings are broadly consistent with those reported in U.S. military cohorts. Teyhen et al. (2014) observed that performance on functional movement tasks, including the UQYBT, was significantly influenced by age and sex, with younger service members and males performing better [11]. In our study, the 26–30-year age group demonstrated peak scores, aligning with the notion that neuromuscular efficiency and control are optimal in young adulthood. Schwiertz et al. (2021) established normative UQYBT values for European adolescents and reported substantial variability across age categories, with performance stabilizing in later adolescence [15]. Compared with their data, our South Indian adult cohort showed lower absolute reach distances but similar normalized scores, emphasizing the importance of anthropometric adjustments and region-specific norms. More recently, Steele and Valentin (2024) synthesized evidence from multiple cohorts and highlighted that both intrinsic (e.g., sex, limb dominance) and extrinsic (e.g., sport participation, training background) factors influence UQYBT performance [21]. Our results support this framework, demonstrating sex-related differences that diminish after normalization, as well as age-related trends consistent with physiological development and neuromuscular adaptations. However, these differences diminished after normalization to limb length, aligning with previous U.S.-based studies that reported no significant sex or age differences post-normalization [11].
In addition, to support our findings, a study reported that age and sex influence UQYBT scores, with older individuals and males generally performing better [21]. Our data also revealed a curvilinear performance distribution, peaking between ages 26 and 29 (Fig 4), possibly reflecting optimal neuromuscular control, proprioception, and mobility during this life stage [22]. Although adolescent scores tend to vary more, this study broadens the understanding of normative values within a stable adult population.
The UQYBT has demonstrated moderate-to-excellent test-retest reliability and low side-to-side asymmetry in healthy adults [23,24]. Our results further validate its utility as a tool for assessing closed-chain upper extremity function. Beyond clinical diagnostics, the UQYBT can aid in injury prevention screening and guide individualized rehabilitation, particularly in overhead sports like swimming, volleyball, and handball where shoulder injuries are prevalent [25–27]. Establishing region-specific normative values improves clinical decision-making and supports more tailored interventions. Together, these findings place our work within a broader international context. While normative UQYBT data from Western cohorts provide useful benchmarks, our study contributes region-specific reference values for South Indian adults, which are necessary for accurate injury risk screening, return-to-play decisions, and rehabilitation planning in this population.
Clinical Implications
The normative reference values from this study serve as practical benchmarks for physical therapists, athletic trainers, and sports physicians evaluating upper limb function in young adults. They may assist with return-to-sport decisions, early identification of individuals at risk for shoulder dysfunction, and development of sport- or task-specific rehabilitation programs.
Limitations
This study was conducted at a single center, which may limit generalizability. Larger multicentre studies with a larger sample and more diverse cohorts would further enhance the generalizability of these reference values. The absence of randomized testing sequences may have introduced fatigue-related bias. Furthermore, not controlling for the socioeconomic status of participants, along with the focus on adults aged 18–36 years, limits the applicability of the findings to individuals from different economic backgrounds and to older populations.
Future directions
Future research should include multicenter trials with more diverse age groups (particularly >40 years), broader ethnic representation, and various athletic populations. Studies should assess test–retest and inter-rater reliability in injured cohorts and explore the predictive value of UQYBT asymmetry in injury prevention. Sport-specific applications also warrant further exploration.
Conclusion
This study establishes normative UQYBT values in healthy Indian adults aged 18–36 years. The observed sex-specific differences and age-related trends provide important reference data for clinicians and researchers conducting upper extremity assessment. These findings enhance the test’s value in injury screening, rehabilitation planning, and performance optimization in active populations.
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