Statistical Primer for Athletic Trainers: The Essentials of Understanding Measures of Reliability and Minimal Important Change

Assessing the robustness of muscle strength and physical performance measures in women older than 40 years: a test-retest reliability study

OBJECTIVES

This study investigated the test-retest reliability and minimal detectable change (MDC) of muscle strength and physical performance tests in women older than 40 years.

METHODS

A total of 113 women, aged 58 ± 11 years (82% postmenopausal women), with a body mass index of 28.5 ± 5.8 kg/m 2 , participated in this study. One-repetition maximum (1RM) tests were conducted for seven strength exercises: 45° leg press, bench press, leg extension, pec deck, wide-grip lateral pull-down, leg curl, and seated cable row, with a retest after 48 hours. Timed Up and Go (TUG), 6-minute walk, and 30-second sit-to-stand tests were performed on the same day and retested after 72 hours. The tests and retests were administered by the same evaluators. Relative reliability (consistency of participant rank between test-retest) was assessed using the intraclass correlation coefficient for consistency and agreement, and absolute reliability (precision of score) was assessed using the MDC based on the standard error of prediction.

RESULTS

The 1RM and performance tests exhibited excellent reliability: 45° leg press (consistency, 0.99; agreement, 0.98), bench press (consistency, 0.96; agreement, 0.96), leg extension (consistency, 0.93; agreement, 0.91), pec deck (consistency, 0.90; agreement, 0.88), wide-grip lateral pull-down (consistency, 0.91; agreement, 0.89), leg curl (consistency, 0.84; agreement, 0.83), seated cable row (consistency, 0.92; agreement, 0.94), TUG (consistency, 0.87; agreement, 0.87), 6-minute walk (consistency, 0.96; agreement, 0.95), and 30-second sit to stand (consistency, 0.85; agreement, 0.80). These tests showed meaningful MDC values, particularly for the 1RM test performed on the machine and the 30-second sit-to-stand test: 45° leg press, 22.2 kg (15%); bench press, 4.9 kg (19%); leg extension, 9.2 kg (35%); pec deck, 8.8 kg (44%); wide-grip lateral pull-down, 9.4 kg (31%); leg curl, 9.2 kg (51%); seated cable row, 11.4 kg (29%); TUG, 1.4 seconds (20%); 6-minute walk, 50.9 m (10%); and 30-second sit to stand, 4.6 reps (30%).

CONCLUSIONS

Although the muscle strength and physical performance tests demonstrate excellent relative reliability in women older than 40 years, they exhibit low absolute reliability, particularly the 1RM test performed on the machine and the 30-second sit-to-stand test. Therefore, although these tests show good consistency in the positioning of women within the group after repeated measures, their precision measure is relatively low (high fluctuation). Changes in these tests that are smaller than the MDC may not indicate real changes in women at middle age and older.

Measuring what matters in healthcare: a practical guide to psychometric principles and instrument development

The provision of quality healthcare relies on scales and measures with robust evidence of their psychometric properties. Using measurement instruments with poor reliability, validity, or feasibility, or those that are not appropriate for the target diagnostic group or construct/dimension under consideration, may be unfavorable for patients, unproductive, and hinder empirical advancement. Resources from the COnsensus-based Standards for the selection of health status Measurement INstruments (COSMIN) group can assist in identifying and developing psychometrically sound measures. The COSMIN initiative is the only international, research-based practice taxonomy and methodological guidelines for measurement in healthcare. This manuscript aims to provide an accessible introduction to theories, principles and practices of psychometrics, instrument properties, and scale development, with applied examples from the COSMIN recommendations. It describes why measurement in healthcare is critical to good practice, explains the concepts of the latent variable and hypothetical construct and their importance in healthcare assessments, explores issues of flawed measurement and briefly explains key theories relevant to psychometrics. The paper also outlines a ten-step process to develop and validate a new measurement instrument, with examples drawn from a recently developed visuoperceptual measure for analysis of disordered swallowing to demonstrate key concepts and provides a guide for understanding properties of and terminology related to measurement instruments. This manuscript serves as a resource for healthcare clinicians, educators, and researchers who seek to develop and validate new measurement instruments or improve the properties of existing ones. It highlights the importance of using psychometrically sound measurement instruments to ensure high-quality healthcare assessments.

Reliability of Upper Extremity Functional Performance Tests for Overhead Sports Activities

Background

There is lack of consensus on which tests, particularly upper extremity functional performance tests (FPT) that should be used for clinical decision making to progress a patient through a rehabilitation program or criteria for return to sport (RTS). Consequently, there is a need for tests with good psychometric properties that can be administered with minimal equipment and time.

Purpose

(1) To establish the intersession reliability of several open kinetic chain FPT in healthy young adults with a history of overhead sport participation. (2) To examine the intersession reliability of the limb symmetry indices (LSI) from each test.

Study Design

Test-retest reliability, single cohort study.

Methods

Forty adults (20 males, 20 females) completed four upper extremity FPT during two data collection sessions three to seven days apart: 1) prone medicine ball drop test 90°shoulder abduction (PMBDT 90°), 2) prone medicine ball drop test 90°shoulder abduction/90° elbow flexion (PMBDT 90°-90°), 3) half-kneeling medicine ball rebound test (HKMBRT), 4) seated single arm shot put test (SSASPT). Measures of systematic bias, absolute reliability and relative reliability were computed between the sessions for both the original test scores and LSI.

Results

Except for the SSASPT, all tests demonstrated significant (p ≤ 0.030) improvements in performance during the second session. Generally, for the medicine ball drop/rebound tests, the absolute reliability was the highest (less random error) for the HKMBRT, next the PMBDT 90°followed by PMBDT 90°-90°. Excellent relative reliability existed for the PMBDT 90°, HKMBRT, and SSASPT, whereas fair to excellent relative reliability for the PMBDT 90°-90°. The SSASPT LSI revealed the highest relative and absolute reliability.

Conclusion

Two tests, HKMBRT and SSASPT demonstrated sufficient reliability; therefore, the authors' recommend those tests can be used for serial assessments to advance a patient through a rehabilitation program as well as criteria for progression to RTS.

Level of Evidence

3.

Between-Session Reliability of Strength- and Power-Related Variables Obtained during Isometric Leg Press and Countermovement Jump in Elite Female Ice Hockey Players

Isometric leg press (ILP) and countermovement jump (CMJ) are commonly used to obtain strength- and power-related variables with important implications for health maintenance and sports performance. To enable the identification of true changes in performance with these measurements, the reliability must be known. This study evaluates the between-session reliability of strength- and power-related measures obtained from ILP and CMJ. Thirteen female elite ice hockey players (21.5 ± 5.1 years; 66.3 ± 8.0 kg) performed three maximal ILPs and CMJs on two different occasions. Variables from the ILP (peak force and peak rate of force development) and CMJ (peak power, peak force, peak velocity, and peak jump height) were obtained. The results were reported using the best trial, an average of the two best trials, or an average of three trials. The intraclass correlation coefficient (ICC) and coefficient of variation (CV) were high (ICC > 0.97; CV < 5.2%) for all outcomes. The CV for the CMJ (1.5-3.2%) was lower than that for the ILP (3.4-5.2%). There were no differences between reporting the best trial, an average of the two best trials, or an average of the three trials for the outcomes. ILP and CMJ are highly reliable when examining strength- and power-related variables in elite female ice hockey players.

Self-performed Five Times Sit-To-Stand test at home as (pre-)screening tool for frailty in cancer survivors: Reliability and agreement assessment

AIMS AND OBJECTIVES

The self-performance of a Five-Times-Sit-To-Stand (FTSTS)-test, without the usual supervision by a medical professional, provides valuable opportunities for clinical practice and research. This study aimed: (1) to determine the validity of the self-performed FTSTS test in comparison to a supervised reference test and (2) to determine the reliability of a self-performed FTSTS test by cancer survivors.

BACKGROUND

Early detection of frailty in cancer survivors may enable prehabilitation interventions before surgery or intensive treatment, improving cancer outcomes.

DESIGN

A repeated measures reliability and agreement study, with one week in between measures, was performed.

METHODS

Cancer survivors (n = 151) performed two FTSTS tests themselves. One additional reference FTSTS test was supervised by a physical therapist. The intraclass correlation coefficient (ICC), structural error of measurement (SEM) and minimally important clinical difference (MID) were calculated comparing a self-performed FTSTS test to the reference test, and comparing two self-performed FTSTS tests. The Guidelines for Reporting Reliability and Agreement Studies (GRASS) have been used.

RESULTS

Mean age of cancer survivors was 65.6 years (SD = 9.3), 54.6% were female, median time since diagnosis was 2 years [IQR = 1], and tumour type varied (e.g., breast cancer (31.8%), prostate cancer (17.2%), gastrointestinal cancer (11.9%) and haematological cancer (11.9%)). Validity of the self-performed FTSTS test at home was acceptable in comparison with the reference test (ICC = .74; SEM = 3.2; MID = 3.6) as was the reliability of the self-performed FTSTS test (ICC = .70; SEM = 2.2; MID = 3.8).

CONCLUSIONS

The self-performed FTSTS test is a valid and reliable measure to assess lower body function and has potential to be used as objective (pre-)screening tool for frailty in cancer survivors.

RELEVANCE TO CLINICAL PRACTICE

The self-performed FTSTS test at home may indicate the cancer survivors in need of prehabilitation in advance of surgery or intensive treatment. The feasibility, short amount of time needed and potential cost-effectiveness of the self-performed FTSTS test can make it a valuable contribution to personalised care and precision medicine.

Participant-Level Analysis of the Effects of Interventions on Patient-Reported Outcomes in Patients With Chronic Ankle Instability

CONTEXT

Intervention studies for chronic ankle instability (CAI) often focus on improving physical impairments of the ankle complex. However, using an impairments-focused approach may miss psychological factors that may mediate function and recovery. Patient-reported outcome (PRO) measures can be used to assess several dimensions of the health-related quality of life (HRQoL) and deliver enhanced patient-centered care. Therefore, the purpose of this investigation was to evaluate group-level improvements in HRQoL and treatment response rates following various interventions in patients with CAI.

DESIGN

Cross-sectional.

METHODS

Data from 7 previous studies were pooled by the chronic ankle instability outcomes network for participant-level analysis, resulting in 136 patients with CAI. Several interventions were assessed including balance training, gait biofeedback, joint mobilizations, stretching, and strengthening, with treatment volume ranging from 1 to 4 weeks. Outcome measures were PROs that assessed ankle-specific function (Foot and Ankle Ability Measure), injury-related fear (Tampa Scale of Kinesiophobia and Fear Avoidance Belief Questionnaire), and global well-being (Disablement in the Physically Active); the PROs assessed varied between studies. Preintervention to postintervention changes were evaluated using separate Wilcoxon signed-rank tests and effect sizes, and a responder analysis was conducted for each PRO.

RESULTS

Significant, moderate to large improvements were observed in PROs that assessed ankle-specific function, injury-related fear, and global well-being following intervention (P < .001). Responder rates ranged from 39.0% to 53.3%, 12.8% to 51.4%, and 37.8% for ankle specific function, injury-related fear, and global well-being, respectively.

CONCLUSIONS

Various interventions can lead to positive improvements in HRQoL in patients with CAI. Treatment response rates at improving HRQoL are similar to response rates at improving impairments such as balance, further reinforcing the need for individualized treatment approaches when treating a patient with CAI.

Differences in health-related quality of life among patients after ankle injury

Ankle sprains are the most common injuries sustained in the physically active, often associated with pain and functional limitations long after initial recovery. In recent years, the impact of ankle sprains on general health and health-related quality of life (HRQoL) has been noted in athletes, but is not well-documented in the general population. We examined differences in HRQoL and general health between individuals with ankle sprain history and healthy controls. Those with ankle sprain reported significantly higher body mass index and general body pain, and lower SF-8 physical component scores than healthy controls. Additionally, there is some indication that physical activity is lower in those with ankle sprain history. This is an important step in illustrating the adverse sequelae of ankle sprains on population health and HRQoL.

Longitudinal Changes in Ultrasound-Assessed Femoral Cartilage Thickness in Individuals from 4 to 6 Months Following Anterior Cruciate Ligament Reconstruction

OBJECTIVE

Diagnostic ultrasound provides a valid assessment of cartilage health that has been used to observe cross-sectional cartilage thickness differences post-ACLR (anterior cruciate ligament reconstruction), but has not been used longitudinally during early recovery post-ACLR.

DESIGN

The purpose of this study was to assess longitudinal changes in femoral cartilage thickness via ultrasound in individuals at 4 to 6 months post-ACLR and compared to healthy controls. Twenty participants (50% female, age = 21.1 ± 5.7 years) completed testing sessions 4 and 6 months post-ACLR. Thirty healthy controls (57% female, age = 20.8 ± 3.8 years) without knee injury history completed 2 testing sessions (>72 hours apart). Femoral cartilage ultrasound images were captured bilaterally in ACLR participants and in the dominant limb of healthy controls during all sessions. Average cartilage thicknesses in the medial, intercondylar, and lateral femoral regions were determined using a semi-automated processing technique.

RESULTS

When comparing cartilage thickness mean differences or changes over time, individuals post-ACLR did not demonstrate between limb differences (P-range = 0.50-0.92), limb differences compared to healthy controls (P-range = 0.19-0.94), or changes over time (P-range = 0.22-0.72) for any femoral cartilage thickness region. However, participants demonstrated cartilage thickening (45%) or thinning (35%) that exceeded minimal detectable change (MDC) from 4 to 6 months post-ACLR, respectively.

CONCLUSIONS

Using MDC scores may help better identify within-subject femoral cartilage thickness changes longitudinally post-ACLR due to bidirectional cartilage thickness changes.

A systematic survey identified methodological issues in studies estimating anchor-based minimal important differences in patient-reported outcomes

OBJECTIVE

To systematically survey the literature addressing the reporting of studies estimating anchor-based minimal important differences (MIDs) and choice of optimal MIDs.

STUDY DESIGN AND SETTING

We searched Medline, Embase and PsycINFO from 1987 to March 2020. Teams of two reviewers independently identified eligible publications and extracted quotations addressing relevant issues for reporting and/or selecting anchor-based MIDs. Using a coding list, we assigned the same code to quotations capturing similar or related issues. For each code, we generated an 'item', i.e. a specific phrase or sentence capturing the underlying concept. When multiple concepts existed under a single code, the team created multiple items for that code. We clustered codes addressing a broader methodological issue into a 'category' and classified items as relevant for reporting, relevant for selecting an anchor-based MID, or both.

RESULTS

We identified 136 eligible publications that provided 6 categories (MID definition, anchors, patient-reported outcome measures, generalizability and statistics) and 24 codes. These codes contained 34 items related to reporting MID studies, of which 29 were also related to selecting MIDs.

CONCLUSION

The systematic survey identified items related to reporting of anchor-based MID studies and selecting optimal MIDs. These provide a conceptual framework to inform the design of studies related to MIDs, and a basis for developing a reporting standard and a selection approach for MIDs.

Validity and reliability of the DiCI for the measurement of shoulder flexion and abduction strength in asymptomatic and symptomatic subjects

Background

A higher risk of shoulder injury in the athletic and non-athletic population is frequently associated with strength deficits. Therefore, shoulder strength assessment can be clinically useful to identify and to quantify the magnitude of strength deficit. Thus, the aim of this study was to evaluate the validity and reliability of a DiCI (a new hand-held dynamometer) for the measurement of shoulder flexion and abduction strength in asymptomatic and symptomatic subjects.

Methods

Forty-three recreational athletes (29 males and 14 females; age: 22.1 ± 0.47 years; body mass: 68.7 ± 13.1 kg; height = 173.3 ± 9.7 cm) and 40 symptomatic subjects (28 males and 12 females; age: 49.9 ± 8.1 years; body mass: 70.6 ± 14.3 kg; height = 171.7 ± 9.0 cm) completed shoulder flexion and abduction strength tests in two identical sessions one-week apart. Both types of movement were evaluated at 45º and 90º.

Results

Relative reliability analysis showed excellent intra-class correlation coefficients (ICC) for all evaluated movements (ICC range = 0.90 to 0.99). Absolute reliability analysis showed a standard error of measurement (SEM) ranging from 1.36% to 2.25%, and minimal detectable change (MDC) ranging from 3.93% to 6.25%. In conclusion, the DiCI is a valid and reliable device for assessing shoulder strength both in recreational athletes and in subjects with restricted mobility and loss of strength.

Test-Retest Reliability of a Functional Reaction Time Assessment Battery

CONTEXT

Reaction time is commonly assessed postconcussion through a computerized neurocognitive battery. Although this measure is sensitive to postconcussion deficits, it is not clear if computerized reaction time reflects the dynamic reaction time necessary to compete effectively and safely during sporting activities. Functional reaction time assessments may be useful postconcussion, but reliability must be determined before clinical implementation.

OBJECTIVE

To determine the test-retest reliability of a functional reaction time assessment battery and to determine if reaction time improved between sessions.

DESIGN

Cohort.

SETTING

Laboratory.

PARTICIPANTS

Forty-one participants (21 men and 20 women) completed 2 time points. Participants, on average, were 22.5 (2.1) years old, 72.5 (11.9) cm tall, had a mass of 71.0 (13.7) kg, and were mostly right leg and hand dominant (92.7%).

INTERVENTIONS

Participants completed 2 clinical reaction time tests (computerized Stroop and drop stick) and 5 functional reaction time tests (gait, jump landing, single-leg hop, anticipated cut, and unanticipated cut) across 2 sessions. Drop stick and functional reaction time assessments were performed in single (motor task only) and dual task (motor task with cognitive task).

MAIN OUTCOME MEASURES

Reaction time (in seconds) was calculated during all assessments. Test-retest reliability was determined using 2-way mixed-effects intraclass correlation coefficients (3, k). Paired samples t tests compared mean reaction time between sessions.

RESULTS

Test-retest reliability was moderate to excellent for all reaction time outcomes (intraclass correlation coefficients [3, k] range = .766-.925). Several statistically significant between-session mean differences were observed, but effect sizes were negligible to small (d range = 0.05-0.44).

CONCLUSIONS

The functional reaction time assessment battery displayed similar reliability to the standard computerized reaction time assessment battery and may provide important postinjury information, but more research is needed to determine clinical utility.

Innovative alignment of sprinting prostheses for persons with transfemoral amputation: Exploratory study on a gold medal Paralympic athlete

BACKGROUND

Recommendations for the alignment of the socket and foot in the sprinting prosthesis of athletes with transfemoral amputation are either based on walking biomechanics or lack public scientific evidence.

OBJECTIVES

To explore the biomechanical changes and the sensations of a gold medal Paralympic sprinter, while running with three bench alignments: a conventional reference (A0), an innovative alignment based on the biomechanics of elite able-bodied sprinters (A2), and an intermediate alignment (A1).

STUDY DESIGN

Single subject with repeated measures.

METHODS

A1 and A2 feature a progressively greater socket tilt and a plantar-flexed foot compared to A0. The 30-year-old female athlete trained with three prostheses, one per alignment, for at least 2 months. We administered a questionnaire to collect her impressions. Then, she ran on a treadmill at full speed (5.5 m/s). We measured the kinematics and moments of the prosthetic side, and the ground reaction forces of both sides.

RESULTS

A2 reduced the prosthetic side hip extension at foot-off while preserving hip range of motion, decreased the impulse of the hip moment, and increased the horizontal propulsion, leaving sufficient margin to prevent knee buckling without increasing sound side braking forces. Biomechanical outcomes matched well with subjective impressions.

CONCLUSIONS

A2 appears promising to improve the performance and comfort of sprinters with transfemoral amputation, without compromising safety.

CLINICAL RELEVANCE

Observation of elite able-bodied sprinters led to the definition of a new specific alignment for the sprinting prosthesis of athletes with transfemoral amputation, which appears promising to improve performance and comfort, without compromising safety. This may constitute a major improvement compared to alignments based on walking biomechanics.

Heart Rate Variability in Women with Systemic Lupus Erythematosus: Association with Health-Related Parameters and Effects of Aerobic Exercise

Abnormal heart rate variability (HRV) has been observed in patients with systemic lupus erythematosus (SLE). In a combined cross-sectional and interventional study approach, we investigated the association of HRV with inflammation and oxidative stress markers, patient-reported outcomes, and the effect of 12 weeks of aerobic exercise in HRV. Fifty-five women with SLE (mean age 43.5 ± 14.0 years) were assigned to either aerobic exercise (n = 26) or usual care (n = 29) in a non-randomized trial. HRV was assessed using a heart rate monitor during 10 min, inflammatory and oxidative stress markers were obtained, psychological stress (Perceived Stress Scale), sleep quality (Pittsburg Sleep Quality Index), fatigue (Multidimensional Fatigue Inventory), depressive symptoms (Beck Depression Inventory), and quality of life (36-item Short-Form Health Survey) were also assessed. Low frequency to high frequency power (LFHF) ratio was associated with physical fatigue (p = 0.019). Sample entropy was inversely associated with high-sensitivity C-reactive protein (p = 0.014) and myeloperoxidase (p = 0.007). There were no significant between-group differences in the changes in HRV derived parameters after the exercise intervention. High-sensitivity C-reactive protein and myeloperoxidase were negatively related to sample entropy and physical fatigue was positively related to LFHF ratio. However, an exercise intervention of 12 weeks of aerobic training did not produce any changes in HRV derived parameters in women with SLE in comparison to a control group.

Test-retest repeatability reveals a temporal kinematic signature for an upper limb precision grasping task in adults

Hand-eye coordination skills, such as reaching and grasping, are fundamentally important for the performance of most daily activities. Upper limb kinematics recorded by motion tracking systems provide detailed insight into the central nervous system control of movement planning and execution. For example, kinematic metrics can reveal deficits in control, and compensatory neuromotor strategies in individuals with neuropathologies. However, the clinical utility of kinematic metrics is currently limited because their psychometric properties, such as test-retest repeatability, have not been well characterized. Therefore, the purpose of this study was to examine the degree of repeatability of spatiotemporal kinematic metrics and determine which, if any, measures form a kinematic signature for a precision grasping task. Healthy adults (n = 40) were tested on two occasions separated by 5-10 days on a bead threading task consisting of reaching and precision grasping. Results showed good test-retest repeatability for reach peak velocity, reach and grasp durations, whereas poor to moderate reliability was observed for measures of spatial precision and maximum grip aperture. In addition, analysis showed that reliable estimates of kinematic metrics can be obtained using 10 trials. Overall, our results indicate that reach peak velocity and temporal metrics form a stable characteristic, or a kinematic signature, of individual performance on a standardized bead threading task. These findings suggest potential utility in applying kinematic metrics for clinical assessment of upper limb reaching tasks.

WITHIN-SESSION RELIABILITY FOR INTER-LIMB ASYMMETRIES IN ANKLE DORSIFLEXION RANGE OF MOTION MEASURED DURING THE WEIGHT-BEARING LUNGE TEST

BACKGROUND

The identification of asymmetrical inter-limb ankle dorsiflexion range of motion (DF ROM) has the potential to influence the course of treatment during the rehabilitation process, with limitations in ankle DF ROM potentially increasing injury risk. However, reliability for methods to identify ankle DF ROM asymmetries remain under described in the literature.

PURPOSE

To determine the reliability of the trigonometric calculation method for measuring ankle DF ROM during the weight-bearing lunge test (WBLT) for both a single limb and the symmetry values. The secondary purpose was to establish values of ankle DF ROM asymmetry and identify the influence of leg dominance on ankle DF ROM.

STUDY DESIGN

Cross-sectional study.

METHODS

Ankle DF ROM was measured bilaterally in 50 healthy and recreationally active participants (28 men, 22 women, age = 22 ± 4 years, height = 172.8 ± 10.8 cm, body mass 71.5 ± 15.1 kg), using the trigonometric measurement method during the WBLT. Each ankle was measured twice in a single testing session to establish within-session reliability.

RESULTS

Values are presented for asymmetries in DF ROM. No differences were identified between the dominant and non-dominant limb (p = 0.862). Within-session reliability for measuring a single limb was classified as 'good' (ICC = 0.98) with a minimal detectable change value of 1.7 °. For measuring ankle DF ROM asymmetry, reliability was established as 'good' (ICC = 0.85) and a minimal detectable change value of 2.1 ° was determined.

CONCLUSIONS

Although symmetry in ankle DF ROM may not be assumed, the magnitude of asymmetry may be less than previously reported in a population of recreationally active individuals. Discrepancies between previous research and the findings of the present study may have been impacted by differences in measurement methods. Furthermore, clinicians should be aware that the error associated with measures of asymmetry for ankle DF ROM during the WBLT is greater than that of a single limb.

LEVEL OF EVIDENCE

2b.

Reliability of two-dimensional measures associated with bilateral drop-landing performance

The aim of this study was to establish the within-session reliability for two-dimensional (2D) video analysis of sagittal- and frontal-plane measures during bilateral drop-landing tasks. Thirty-nine recreational athletes (22 men, 17 women, age = 22 ± 4 years, height = 1.74 ± 0.15 m, body mass 70.2 ± 15.1 kg) performed five bilateral drop-landings from 50, 100 and 150% of maximum countermovement jump height, twice on the same day. Measures of reliability for initial contact angle, peak flexion angle and joint displacement for the hip, knee, and ankle joints, frontal-plane projection angles (FPPA), as well as inter-limb asymmetries in joint displacement were assessed. No systematic bias was present between trials (P>0.05). All kinematic measurements showed relative reliability ranging from large to near perfect (ICC = 0.52–0.96). Absolute reliability ranged between measures, with CV% between 1.0–1.6% for initial contact angles, 1.9–7.9% for peak flexion angles, 5.3–22.4% for joint displacement, and 1.6–2.3% for FPPA. Absolute reliability for inter-limb asymmetries in joint displacement were highly variable, with minimal detectable change values ranging from 6.0–13.2°. Therefore, 2D video analysis is a reliable tool for numerous measures related to the performance of bilateral drop-landings.

Relative and absolute within-session reliability of the modified Star Excursion Balance Test in healthy elite athletes

Background

The Star Excursion Balance Test (SEBT) is commonly used to assess dynamic postural balance both in clinical practice and research. The aim of our study was to assess the within-session relative and absolute reliability of participants’ performance of the modified SEBT (mSEBT) using a single practice trial in healthy elite athletes who were familiar with the test.

Methods

An intra-session repeated-measures design was used to investigate the relative and absolute reliability of participants’ (healthy athletes partaking in sports at a high-risk of ankle sprain injury) performance of the mSEBT. A total of 122 healthy elite athletes from soccer (n = 73), basketball (n = 15), and volleyball (n = 34) performed one practice trial and three test trials within one session, in three directions (anterior, postero-medial, and postero-lateral), for both legs. Intraclass correlation coefficient (ICC), standard error of measurement (SEM), and smallest detectable change at a 95% confidence were calculated.

Results

We found a good to excellent relative within-session intra-rater reliability between the three trials on specified directions, with an ICC (3,1) from 0.90 to 0.95. SEM and SDC₉₅ for normalized and composite scores, for both legs ranged from 0.91 to 2.86, and 2.54 to 7.94, respectively.

Conclusions

In conclusion, we report good to excellent within-session reliability for the mSEBT. Our results confirm that the test can be reliably used with only one practice trial in healthy elite athletes familiar with the test.

Low Back Pain: The Potential Contribution of Supraspinal Motor Control and Proprioception

Motor control, which relies on constant communication between motor and sensory systems, is crucial for spine posture, stability and movement. Adaptions of motor control occur in low back pain (LBP) while different motor adaption strategies exist across individuals, probably to reduce LBP and risk of injury. However, in some individuals with LBP, adapted motor control strategies might have long-term consequences, such as increased spinal loading that has been linked with degeneration of intervertebral discs and other tissues, potentially maintaining recurrent or chronic LBP. Factors contributing to motor control adaptations in LBP have been extensively studied on the motor output side, but less attention has been paid to changes in sensory input, specifically proprioception. Furthermore, motor cortex reorganization has been linked with chronic and recurrent LBP, but underlying factors are poorly understood. Here, we review current research on behavioral and neural effects of motor control adaptions in LBP. We conclude that back pain-induced disrupted or reduced proprioceptive signaling likely plays a pivotal role in driving long-term changes in the top-down control of the motor system via motor and sensory cortical reorganization. In the outlook of this review, we explore whether motor control adaptations are also important for other (musculoskeletal) pain conditions.

Principles of Statistics: What the Sports Medicine Professional Needs to Know

Understanding the results and statistics reported in original research remains a large challenge for many sports medicine practitioners and, in turn, may be among one of the biggest barriers to integrating research into sports medicine practice. The purpose of this article is to provide minimal essentials a sports medicine practitioner needs to know about interpreting statistics and research results to facilitate the incorporation of the latest evidence into practice. Topics covered include the difference between statistical significance and clinical meaningfulness; effect sizes and confidence intervals; reliability statistics, including the minimal detectable difference and minimal important difference; and statistical power.