Intersession reliability of the upper quarter Y balance test score

1

Keywords:

• Shoulder
• instability
• return to sport
• upper limb

1. Introduction

Shoulder injuries occur frequently in sports involving upper extremities, leading to temporary retirement from sport for conservative or surgical treatment. The decision to return to sport after injury is mainly time-based, which limits a return at the pre-injury level safely. Currently, several studies focused on shoulder functional tests to improve the decision-making process for returning-to-sport.

In this context, the Upper Quarter Y Balance Test (UQYBT) is performed to assess the dynamic stability and proprioception of the upper limbs (Gorman et al. 2012). While the participant stands in one-handed push up position, the other hand has to reach maximal distance in medial, superolateral and inferolateral directions (Figure 1). The maximal distance in each direction and the average of these three distances present all high test-retest reliability for both upper extremities (Intraclass Correlation Coefficient (ICC) ranged from 0.91 to 0.95; (Gorman et al. 2012; Westrick et al. 2012). However, UQYBT performed by both upper extremities allows a score to be computed when divided the distances reached with a hand by those reached with controlateral hand. Such score is commonly used to assess side-to-side difference in reference to the dominant limb (Westrick et al. 2012) but, in the field of rehabilitation, such a score may be used to express performance of the injured limb with respect to the uninjured one (Thomeé et al. 2011), assessing the limb symmetry index. Regardless the upper extremity used as reference and to the best of our knowledge, the test-retest reliability of the UQYBT score has not been evaluated yet, limiting its use as a criterion for return to sport.

Figure 1. Illustration of the UQYBT performance for the medial (left), inferolateral (middle) and superolateral (right) directions.

The purpose of this study was to assess the intersession reliability of the score set from UQYBT. It was hypothesized that the score met all reliability criteria.

2. Methods

Ten right handed male athletes (Age: 25.8 ± 4.4 years; height: 176.5 ± 8.6 cm; mass: 75.2 ± 4.9 kg) were recruited to participate in this study, which was approved by the ethical committee (#2018-A0301352). Inclusion criteria were being 18–35 years-old and having declared no upper limb problems at the time of the study. Exclusion criteria were having undergone surgery at the upper limb, or sustaining any injury at the upper limb in the past six months preceding the study. For each participant, the limb lengths between the spinous process of C7 and tip of the middle finger, when the arms were abducted at 90° in the frontal plane, were measured for both upper limbs, using a tape (right: 88.8 ± 4.6 cm; left: 88.8 ± 4.5 cm).

Each participant performed two sessions of UQYBT one week apart. After a standardized warm up, the participant performed UQYBT using YBT Kit (Move2Perform, Evansville, IN, USA), as described by Gorman et al. (2012). Briefly, while standing in one-handed push up position with feet at shoulder width apart and extended elbow, the participant was instructed to push boxes, as far as possible, in the medial (M), inferolateral (IL), and superolateral (SL) directions (Figure 1), orderly, with no hip motion.

Three trials were performed per upper extremity, with 1-min recovery between trials. The maximal distances in each direction and in each side were recorded and normalized by the respective moving limb length to set reach distances by direction (D_M, D_IL, D_SL) reported as a percentage of limb length (%LL). These distances were averaged to compute the composite distance (D_C) per side. Four scores were also calculated when dividing distance of the dominant side by that of controlateral one for each and composite directions (SM, SIL, SSL, SC).

Test-retest reliability for distances and scores was assessed using ICC with confident interval at 95% confidence level, Standard Error of Measurement (SEM) with confident interval at 95% confidence level, Minimal Detectable Change at 95% confidence level (MDC_95%) and coefficient of stability (R²) (Hopkins, 2007). Reliability and stability were good when ICC and R² values, respectively, higher than 0.70, with minimal values for SEM and MDC_95%.

3. Results and discussion

Regardless of the dominance and the session, the medial distance was higher than inferolateral and superolateral ones (Figure 2), as previously reported (Gorman et al. 2012). For the two sessions, mean scores were ranged from 99.7% for the medial direction to 101.7% for the superolateral direction, with a mean composite score of 100.5%. In line with our results, Westrick et al. (2012) described scores ranged from 95.1% for the superolateral direction to 99.4% for the medial direction, and a composite score of 97.9%.

Figure 2. Mean (± standard deviation) distances (top) and scores (bottom) in medial (M), inferolateral (IL), superolateral (SL), and composite (C) directions for sessions 1 (light grey) and 2 (dark grey) D_M, D_IL, D_SL and D_C as well as S_M, S_SL, S_C showed good test-rest reliability and stability (Table 1). S_IL presented fair reliability. Concerning distances, the superolateral direction produced the highest reliability whereas the inferolateral direction produced the lowest reliability, as described by Gorman et al. (2012).

4. Conclusions

Composite score set from UQYBT met all reliability criteria. It can be considered as a reliable tool to quantify side-to-side difference in upper limbs. Its use may be relevant on healthy athletic population for asymmetry measurement or after an injury to objectify functional deficit. Thus, in a rehabilitation context, the UQYBT score may be used as a criterion to complete the decision-making process for returning-to-sport. Further studies however need to assess also the validity and sensitivity of the UQYBT.

Table 1. Intersession reliability for distances and scores by directions.

ICC		SEM	MDC95%	R^2
DM	0.95 [0.80;0.99]	1.6 [1.1;3.0]	4.5	0.88
DIL	0.89 [0.63;0.97]	2.3 [1.6;4.2]	6.4	0.77
DSL	0.97 [0.89;0.99]	1.8 [1.3;3.4]	5.1	0.94
DC	0.96 [0.85;0.99]	1.5 [1.0;2.7]	4.1	0.90
SM	0.92 [0.72;0.98]	1.8 [1.1;3.2]	4.9	0.82
SIL	0.57 [-0.05;0.87]	3.2 [2.2;5.8]	8.9	0.88
SSL	0.94 [0.75;0.99]	3.5 [2.4;6.5]	9.8	0.88
SC	0.93 [0.76;0.98]	1.6 [1.1;3.0]	4.5	0.86

Acknowledgements

Authors thank G. Vigne, V. Bourquin, D. Juré (Athletic) for their help.

Additional information

Funding

This study was supported by “Ramsey Générale de Santé”, Paris, France (COSRGDS-2018-06-037).