Statistical Primer for Athletic Trainers: Using Confidence Intervals and Effect Sizes to Evaluate Clinical Meaningfulness

The influence of exercise therapy dosing on pain and functional outcomes in patients with subacromial pain syndrome: A systematic review

Background

The objective was to identify exercise therapy dosing parameters for subacromial pain syndrome (SAPS) associated with improved pain and function outcomes (via effect sizes) and determine the extent of exercise intervention reproducibility.

Methods

An electronic search of PubMed/MEDLINE, Cumulative Index to Nursing and Allied Health Literature, EMBASE, Cochrane Database of Systematic Reviews, and SportDiscus identified studies that used exercise therapy exclusively to treat SAPS. Exercise therapy dosing parameters were extracted and within-group effect sizes were calculated for all pain and functional outcomes. Template for Intervention Description and Replication and Consensus on Exercise Reporting were used to record intervention reporting. The risk of bias and Grading of Recommendations, Assessment, Development, and Evaluation were assessed by two reviewers.

Results

Twenty-one trials with 674 subjects were included. Effect sizes for pain and function were large in 18 studies, medium in six studies, and small or no effect in four studies, despite the type of supervision. With moderate certainty, effect sizes of pain and function were not influenced by exercise therapy dosing parameters. Intervention reporting was generally poor.

Discussion

Exercise therapy for SAPS was associated with large effect sizes for improvement in pain and function but optimal exercise therapy dosing parameters could not be identified. Strong recommendations conditionally suggest treating SAPS with a variety of exercise therapy dosing parameters.

The Effects Of Differing Density Of Swim-Training Sessions On Shoulder Range Of Motion and Isometric Force Production In National and University Level Swimmers

Background

Well-developed physical qualities (i.e., greater load capacity) in athletes can provide protection against injuries. Although higher competitive level swimmers have more developed physical qualities, no studies have investigated how physical qualities of the shoulder respond to a swim-training session in different competitive levels.

Purpose

To compare baseline shoulder external rotation range of motion (ER ROM) and isometric peak torque of the shoulder internal rotators (IR) and external rotators (ER) between national and university level swimmers with differing training volumes. To compare the post-swim changes of these physical qualities between groups.

Study design

Cross-sectional.

Methods

Ten male swimmers (age= 18.7 ± 1.2 years) were divided into high-load (N= 5 national-level, weekly swim-volume= 37.0 ± 2.7 km) and low-load groups (N= 5 university-level, weekly swim-volume= 6.8 ± 1.8 km). For each group, shoulder active ER ROM and isometric peak torque of the shoulder IR and ER were measured before and immediately after a high-intensity swim-training session (for each group, the hardest swim-session of the week was analyzed). The results were evaluated by the level of significance (p-value), effect size, and whether changes exceeded the measurement error.

Results

University-level swimmers had lower baseline ER torque (p= 0.006; d= 2.55) and IR torque (p= 0.011; d= 2.42) than national-level swimmers. For post-swim analysis, ER ROM decreased more in university swimmers (change= -6.3° to -8.4°; d= 0.75-1.05) than national counterparts (change= -1.9° to -5.7°; d= 0.43-0.95). Greater drops in rotation torque were found in university swimmers (IR change= -15% to -21.0%; d= 0.83-1.66; ER change= -9.0% to -17.0%; d= 1.14-1.28) compared to national swimmers (IR change= -10.0% to -13.0%; d= 0.61-0.91; ER change= -3.7% to -9.1%; d= 0.50-0.96). The average change of all tests in university swimmers exceeded the minimal detectable change (MDC), whereas in national level swimmers some tests exceeded the MDC. Despite this, only post-swim ER torque in the dominant side (p= 0.003; d= 1.18) was significantly lower in university swimmers (possibly due to the small sample size).

Conclusions

University swimmers have less baseline shoulder external and internal rotator torque and had greater drops of all shoulder physical qualities after a swim-training session, which may have implications for injury risk. However, due to the sample size, the results have to be interpreted with caution.

Level of evidence

3.

Preseason weight-bearing ankle dorsiflexion in male professional football players with and without a history of severe ankle injury: A novel analysis in an English Premier League club

OBJECTIVES

Ankle injuries are common in professional football and have profound player/team/club consequences. The weight-bearing lunge-test (WBLT) assesses ankle dorsiflexion range-of-motion in football primary/secondary injury prevention and performance contexts. Data for uninjured and previously ankle-injured players in the English Premier League (EPL) is not available. This study analysed WBLT measurements (cm) within and between uninjured and previously severe ankle-injured players (injured-stiff group, injured-lax group) in one EPL club.

DESIGN

Cross-sectional.

SETTING

Preseason.

PARTICIPANTS

Forty-nine players (age 22.9 ± 4.6 yr; height 181.6 ± 5.2 cm; mass 77.7 ± 7.6 kg).

MAIN OUTCOME MEASURES

Prevalence (%) of previous unilateral severe ankle injury (USAI). Side-to-side (right/left, dominant/nondominant, injured/uninjured) WBLT comparisons at group-level (t-test [within-group]; Welch's ANOVA [between-group]; effect sizes [within-/between-group]) and individual-level (limb symmetry index [%]; absolute-asymmetry [%]).

RESULTS

Prevalence of USAI was 38.7%. There were no statistically-significant side-to-side differences for within-/between-group comparisons. Effect sizes: just-below-large (injured-stiff) and extremely-large (injured-lax) for within-group injured-side/uninjured-side comparisons; just-below-medium (injured-lax) to just-above-medium (injured-stiff) for injured-side comparisons to uninjured players. Absolute-asymmetries: uninjured players, 15.4±13.2%; injured-stiff, 21.8±33.6%; injured-lax 20.4±13.6%.

CONCLUSIONS

Over one-third of players had previous USAI. Effect sizes indicate substantial within-group side-to-side differences and less substantial between-group differences. Across groups, some players had absolute-asymmetries that may elicit concern in ankle primary/secondary injury prevention and performance contexts.

Cardiac-autonomic and hemodynamic responses to a hypertonic, sugar-sweetened sports beverage in physically active men

Hydration practices may confound heart rate variability (HRV) measurements when collected in the pre-training period. We aimed to determine the effects of ingesting a hypertonic, sugar-sweetened sports beverage on HRV and hemodynamic parameters in physically active young men. Fifteen subjects consumed 591 mL of Gatorade (6% carbohydrate, ∼330 mOsmol/kg), 591 mL water, or 10 mL water (control) in random order on separate days following overnight fasting. HRV and hemodynamics were evaluated in 5-min windows immediately before (T1) and 5-10 min (T2), 25-30 min (T3), 40-45 min (T4), and 55-60 min (T5) post-drinking. Root-mean square of successive differences and the standard deviation of normal RR intervals increased post-water intake at all time-points relative to T1 (P < 0.05). No increases were observed post-Gatorade intake, though small effect sizes were noted at T2 and T3 (P > 0.05, ES = 0.27-0.32). Systemic vascular resistance increased at T2 post-Gatorade intake and at T2 and T3 post-water intake (P < 0.05). No interactions were observed for blood pressure measures, stroke volume, or cardiac output. Gatorade does not evoke cardiovascular adjustments to the same magnitude as water. Practitioners should wait at least 45 min to record HRV post-Gatorade intake and >60 min post-water intake. Novelty: Equal volumes of cold water and Gatorade produce inequivalent cardiac-autonomic and hemodynamic responses. HRV responses of greater amplitude and duration were observed following intake of water versus Gatorade. Failure to account for recent fluid intake may result in misinterpretation of autonomic status.

Influence of NICU Nurse Education on Intention to Support Lactation Using Tailored Techniques: A Pilot Study

BACKGROUND

Preterm infants' outcomes improve when fed their mothers' milk. Low percentages of neonatal intensive care unit (NICU) nurses support mothers facing barriers to establishing and sustaining adequate milk supplies. Nurses' motivations and attitudes are instrumental, but understudied, factors in their intention to promote maternal lactation.

PURPOSE

Using the Theory of Reasoned Action, this study explored (1) NICU nurses' attitudes, social pressures, feelings of preparedness, perceptions of comfort, and intention to support lactation; and (2) magnitude of relationships among these concepts before and after undertaking an educational module.

METHODS

A descriptive pre-/postintervention design included a sample of 24 NICU nurses who completed a module, including general lactation and hands-on expressing information. The Nursing Support for Breastfeeding Questionnaire was administered before and after completing the module.

RESULTS

Attitudes, social norms, perception of preparedness, and intention were moderate to high before and after completion of the module. Perception of comfort was moderate. When comparing pre- and postintervention, effect sizes for intention and perception of comfort were moderate. Magnitude of the relationship between attitudes and intention was strong before intervention and moderate after intervention. Subjective norms demonstrated stronger relationships with attitudes and intention after intervention. Preparedness and comfort had stronger relationships with attitudes than with intention both before and after intervention.

IMPLICATIONS FOR PRACTICE

Nurses' attitudes, perception of preparedness, and comfort are modifiable considerations in developing strategies to support evidence-based lactation techniques.

IMPLICATIONS FOR RESEARCH

Additional studies are needed with fully powered and stronger designs to validate findings to guide interventions for nurse support for NICU mothers to optimize lactation.

Feasibility of a set of wrist-worn novice devices for dual motion comparison of the upper limbs during lateral raise motions

Comparison of the upper limbs during natural kinematic motions is necessary for early detection of musculoskeletal imbalance between ipsilateral and contralateral sides in natural settings. Therefore, this study aims to evaluate the feasibility of a novice set of wrist-worn devices designed to assess and compare the dual kinematic motions of the upper limbs during lateral raises. The test-retest and the golden standard and novice device result comparisons were conducted for feasibility assessment of the novice set of devices. Pearson correlation coefficients between 0.65 and 0.88 (P<0.01) and effect sizes between 0.02 and 0.42 indicated feasible application of the novice devices. Considering correlation coefficient of 0.65 between the left and right upper limbs, the results show applicable feasibility of the novice device during lateral raises. In conclusion, the novice set of devices for comparing dual upper limb motions may be applied to assessing and comparing dual upper limb motions for limb motion comparisons and early detection of dysfunctional movements between the limbs.

Instrument-Assisted Soft Tissue Mobilization: A Systematic Review and Effect-Size Analysis

OBJECTIVE

To determine the overall effectiveness of instrument-assisted soft tissue mobilization (IASTM) in improving range of motion (ROM), pain, strength, and patient-reported function in order to provide recommendations for use. We also sought to examine the influence of IASTM on injured and healthy participants, body part treated, and product used.

DATA SOURCES

We searched the Academic Search Premier, Alt Healthwatch, CINAHL Complete, Cochrane Library, MEDLINE with full text, NLM PubMed, Physical Education Index, Physiotherapy Evidence Database (PEDro), SPORTDiscus with full text, and Web of Science databases for articles published from 1997 through 2016. The Boolean string advantEDGE OR astym OR graston OR iastm OR "instrument assist* soft tissue mobil*" OR "augment* soft tissue mobil*" OR "myofascial release" OR "instrument assist* massage" OR "augment* massage" OR "instrument assist* cross fiber massage" was used.

STUDY SELECTION

Included articles were randomized controlled trials that measured ROM, pain, strength, or patient-reported function and compared IASTM treatment with at least 1 other group.

DATA EXTRACTION

Thirteen articles met the inclusion criteria. Four independent reviewers assessed study quality using the PEDro and Centre for Evidence-Based Medicine scales. Twelve articles were included in the effect-size analysis.

DATA SYNTHESIS

The average PEDro score for studies of uninjured participants was 5.83 (range = 5 to 7) and that for studies of injured participants was 5.86 (range = 3 to 7). Large effect sizes were found in outcomes for ROM (uninjured participants), pain (injured participants), and patient-reported function (injured participants). The different IASTM tools used in these studies revealed similar effect sizes in the various outcomes.

CONCLUSIONS

The current literature provides support for IASTM in improving ROM in uninjured individuals as well as pain and patient-reported function (or both) in injured patients. More high-quality research involving a larger variety of patients and products is needed to further substantiate and allow for generalization of these findings.

Statistical Primer for Athletic Trainers: Understanding the Role of Statistical Power in Comparative Athletic Training Research

OBJECTIVE

  To describe the concept of statistical power as related to comparative interventions and how various factors, including sample size, affect statistical power.

BACKGROUND

  Having a sufficiently sized sample for a study is necessary for an investigation to demonstrate that an effective treatment is statistically superior. Many researchers fail to conduct and report a priori sample-size estimates, which then makes it difficult to interpret nonsignificant results and causes the clinician to question the planning of the research design.

DESCRIPTION

  Statistical power is the probability of statistically detecting a treatment effect when one truly exists. The α level, a measure of differences between groups, the variability of the data, and the sample size all affect statistical power.

RECOMMENDATIONS

  Authors should conduct and provide the results of a priori sample-size estimations in the literature. This will assist clinicians in determining whether the lack of a statistically significant treatment effect is due to an underpowered study or to a treatment's actually having no effect.

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.

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

OBJECTIVE

  To describe the concepts of measurement reliability and minimal important change.

BACKGROUND

  All measurements have some magnitude of error. Because clinical practice involves measurement, clinicians need to understand measurement reliability. The reliability of an instrument is integral in determining if a change in patient status is meaningful.

DESCRIPTION

  Measurement reliability is the extent to which a test result is consistent and free of error. Three perspectives of reliability-relative reliability, systematic bias, and absolute reliability-are often reported. However, absolute reliability statistics, such as the minimal detectable difference, are most relevant to clinicians because they provide an expected error estimate. The minimal important difference is the smallest change in a treatment outcome that the patient would identify as important.

RECOMMENDATIONS

  Clinicians should use absolute reliability characteristics, preferably the minimal detectable difference, to determine the extent of error around a patient's measurement. The minimal detectable difference, coupled with an appropriately estimated minimal important difference, can assist the practitioner in identifying clinically meaningful changes in patients.