Introduction
Physical activity can be defined as any bodily movement that requires energy expenditure (WHO, 2024) and is integral to physical, mental and overall well-being.1 2 Approximately 50 million Americans participate in hiking and approximately 60 million people participate in jogging, running and trail running.3 While physical activity has numerous benefits, injuries may occur. An estimated 8.6 million non-emergency sports-related and recreation-related injuries occur annually, leading to 3.8 million emergency room visits.4
Healthcare providers play a crucial role in guiding patients through recovery after injury. The aim is to facilitate a timely return to activity while minimising the risk of reinjury and negative psychological impact, such as increased anxiety.5 6 Providers use impairment-based markers (eg, muscle strength, range of motion)5 6 along with patient-reported outcome measures (PROMs)5 6 to monitor and guide return-to-activity decisions. Assessing psychological variables, like psychological readiness, is essential for gauging a patient’s preparedness to return to activity.5 6 Neglecting psychological readiness may lead to increased reinjury risk, decreased performance and adverse effects on mental health.7–10 Therefore, providers should include psychological PROMs in their assessments alongside disease-oriented variables to inform care decisions and determine the appropriate timing for a return to activity.
Psychological readiness lacks a widely accepted definition7 8; however, the presence of confidence and an absence of fear and anxiety are recognised as essential markers in determining psychological readiness to return to sport.7 9–11 Various questionnaires (eg, ACL Return to Sport after Injury Scale,12 Causes of Re-Injury Worry Questionnaire,13 Athlete Fear Avoidance Questionnaire14) have been designed to measure psychological readiness to return to sport, but most are limited to specific injury groups or may not encompass essential markers of psychological readiness (eg, confidence). The Injury Psychological Readiness to Return to Sport Scale (IPRRS) can be used across various injured populations to measure confidence to augment the fear-based instruments.10
A psychometrically sound scale should have a consistent factor structure, which may be tested using a classic test theory (CTT) approach using exploratory factor analysis (EFA) and confirmatory factor analysis (CFA) procedures.15 16 When using a CTT approach to determine the underlying latent factors, it is recommended performing an EFA and then a subsequent CFA in a separate sample after an initial factor structure has been identified.16 17 Because CTT is sample dependent, the factor structure needs to be established in each new sample.16 Moreover, identified factors should meet recommended Cronbach’s α levels. Low α levels (ie, ≤0.70) indicate poor internal consistency, while high α levels (≥0.90) likely indicate item redundancy, construct under-representation, reduce construct precision or parallel items.18 Further, when choosing appropriate sample size to sufficiently power factor analysis, it is ideal to have at least a 20:1 (ie, number of participants to number of items) ratio.16
While preliminary research provided some evidence for sound measurement properties (eg, test–retest reliability) of the IPRRS, multiple areas of concern have also been identified. For example, factor structure analyses of the IPRRS in different populations using different analysis approaches8 19 20 have yielded mixed solutions. One study using principal components analysis on a sample of 100 Persian athletes produced a two-factor solution with two items representing a ‘confidence to play’ factor and four items representing a ‘confidence in the injured body part and skill level’ factor,19 while another used EFA on a sample of 150 Dutch athletes suffering an ACL injury and produced a one factor, six-item solution.20 Another study that performed CFA on a sample of 100 Italian athletes was used to test two models: poor fit was found for the one factor, six-item model, while more acceptable fit was found for a two-factor model with each factor represented by three items.8 Lastly, internal consistency of the factors has been mixed with some meeting recommended values,8 while others had values outside the range (ie, 0.63; 0.94)19 20
Further psychometric analysis to establish the measurement properties of the IPRRS is needed, including using larger, more diverse (eg, recreational vs competitive athletes) samples to conduct multigroup and longitudinal invariance testing.16 21 Larger sample sizes (>200) would more appropriately support analysis procedures and accurately represent the intended population.16 Multigroup invariance testing ensures factorial stability across relevant subgroups (eg, sex, age, activity type), which indicates subsequently identified group differences are outside of measurement bias or scale error.15 16 22 Sex, age, injury type and athlete status were chosen for subgroup analysis, because they can influence the injury process (ie, injury occurrence, injury response, injury recovery).7 11 Sex and age can influence psychological responses to injury and readiness to return to sport due to biological and developmental differences.11 23 Injury type can impact psychological readiness through variations in recovery processes and perceived severity.7 Athlete status may influence psychological readiness as competitive athletes may experience different pressures and expectations compared with recreational athletes.7
Similarly, longitudinal invariance testing supports repeated use of the scale to assess change over time and establishes that factors are adequately measured across repeated testing.15 16 22 Therefore, the purpose of the study was to assess the factor structure of the IPRRS in a sample of physically active individuals by using CFA. Invariance testing will be used to further establish measurement properties of repeated use (ie, longitudinal invariance) and between groups (ie, multigroup invariance). Further, invariance testing will provide the ability to compare mean differences between groups and across time.