A study of a sample provides only an estimate of the true (population) value of an outcome statistic. A report of the study therefore usually includes an inference about the true value. Traditionally, a researcher makes an inference by declaring the value of the statistic statistically significant or non significant on the basis of a P value derived from a null-hypothesis test. This approach is confusing and can be misleading, depending on the magnitude of the statistic, error of measurement, and sample size. The authors use a more intuitive and practical approach based directly on uncertainty in the true value of the statistic. First they express the uncertainty as confidence limits, which define the likely range of the true value. They then deal with the real-world relevance of this uncertainty by taking into account values of the statistic that are substantial in some positive and negative sense, such as beneficial or harmful. If the likely range overlaps substantially positive and negative values, they infer that the outcome is unclear; otherwise, they infer that the true value has the magnitude of the observed value: substantially positive, trivial, or substantially negative. They refine this crude inference by stating qualitatively the likelihood that the true value will have the observed magnitude (eg, very likely beneficial). Quantitative or qualitative probabilities that the true value has the other 2 magnitudes or more finely graded magnitudes (such as trivial, small, moderate, and large) can also be estimated to guide a decision about the utility of the outcome.
Alan M. Batterham and William G. Hopkins
Angela Papadimitriou and Mark Perry
is not of great clinical significance. Effect sizes are, however, a rather crude and arbitrary estimate of clinical effectiveness. A better estimate is derived from the minimum change in an outcome that has been found to make a difference to patients, often referred to as MICD ( Jaeschke, Singer
Garry T. Allison, Renee Weston, Rachael Shaw, Jocelyn Longhurst, Linda James, Kathleen Kyle, Katrina Nehyba, Suy May Low, and Michelle May
The purpose of this study was to assess the reliability of quadriceps muscle stiffness assessments in individuals with Osgood–Schlatter disease (OSD). Ten subjects were tested for four trials on two occasions within a 2-week period on a Kin-Com dynamometer. A regression coefficient was derived from force-angle data to determine stiffness. Intertriai and interday Intraclass correlations (ICC) and standard error of measurement (SEM) were derived from a repeated-measures ANOVA. Between-trial assessments were more reliable for the outer range 65 to 100° knee flexion (ICC = .95 & .81) than the inner range 35 to 65° knee flexion (ICC = .72 & .57) for both sessions. The average SEMs for outer and inner ranges (over 35°) were 1.1 and 1.3 N, respectively. Assessments between days were less reliable, which may reflect the weekly variation in the presentation of athletes' with- OSD. It remains unclear if the SEM lies within the limits of clinical significance.
Mark T. Suffolk
The sport of competitive bodybuilding is strongly associated with muscle dysmorphia, a body-image-related psychological disorder. This theoretical article draws on existing concepts, namely stereotyping, prejudice, and positive deviance in sport, to explicate the notion that competitive bodybuilding and body-image disturbance may be mistakenly conflated. The perspective offered here goes beyond the countercultural physique to argue that a negative social perception of competitive bodybuilders obscures the pragmatic necessity to develop a hypermesomorphic physique. Competitive bodybuilders (CBs) and athletes in mainstream competitive sport exhibit congruent psychobehavioral tendencies. In a competitive-sport context, behavior among CBs perceived as pathological may primarily represent a response to the ideological sporting ethic of “win at all costs,” not extreme body-image disturbance. Analyzing the psychobehavioral characteristics of CBs within a sporting rather than a pathological framework, allows for a contextual assessment of behaviors to then determine the clinical significance relative to the research population under investigation.
Robert G. McCulloch, Donald A. Bailey, Robert L. Whalen, C. Stuart Houston, Robert A. Faulkner, and Bruce R. Craven
This cross-sectional study compared differences in os calcis bone density and distal radius bone mineral content (BMC) among adolescent soccer players, competitive swimmers, and control subjects. Sixty-eight males and females (23 soccer players, 20 swimmers, 25 controls) ages 13 to 17 served as subjects. The results for os calcis trabecular density indicate a trend that may be of clinical significance and that may warrant further study. The swimmers had the lowest os calcis density in both sexes whereas the soccer players had the highest bone density at this weight-bearing site (F=2.54, p<.08). No differences with respect to distal radius BMC were observed among activity groups or between sexes.
The first sport-science-oriented and comprehensive paper on magnitude-based inferences (MBI) was published 10 y ago in the first issue of this journal. While debate continues, MBI is today well established in sport science and in other fields, particularly clinical medicine, where practical/clinical significance often takes priority over statistical significance. In this commentary, some reasons why both academics and sport scientists should abandon null-hypothesis significance testing and embrace MBI are reviewed. Apparent limitations and future areas of research are also discussed. The following arguments are presented: P values and, in turn, study conclusions are sample-size dependent, irrespective of the size of the effect; significance does not inform on magnitude of effects, yet magnitude is what matters the most; MBI allows authors to be honest with their sample size and better acknowledge trivial effects; the examination of magnitudes per se helps provide better research questions; MBI can be applied to assess changes in individuals; MBI improves data visualization; and MBI is supported by spreadsheets freely available on the Internet. Finally, recommendations to define the smallest important effect and improve the presentation of standardized effects are presented.
Tyler B. Weaver, Christine Ma, and Andrew C. Laing
The Nintendo Wii Balance Board (WBB) has become popular as a low-cost alternative to research-grade force plates. The purposes of this study were to characterize a series of technical specifications for the WBB, to compare balance control metrics derived from time-varying center of pressure (COP) signals collected simultaneously from a WBB and a research-grade force plate, and to investigate the effects of battery life. Drift, linearity, hysteresis, mass accuracy, uniformity of response, and COP accuracy were assessed from a WBB. In addition, 6 participants completed an eyes-closed quiet standing task on the WBB (at 3 battery life levels) mounted on a force plate while sway was simultaneously measured by both systems. Characterization results were all associated with less than 1% error. R 2 values reflecting WBB sensor linearity were > .99. Known and measured COP differences were lowest at the center of the WBB and greatest at the corners. Between-device differences in quiet stance COP summary metrics were of limited clinical significance. Lastly, battery life did not affect WBB COP accuracy, but did influence 2 of 8 quiet stance WBB parameters. This study provides general support for the WBB as a low-cost alternative to research-grade force plates for quantifying COP movement during standing.
J.D. DeFreese, Michael J. Baum, Julianne D. Schmidt, Benjamin M. Goerger, Nikki Barczak, Kevin M. Guskiewicz, and Jason P. Mihalik
Context: Concussion baseline testing helps injury evaluation by allowing postinjury comparisons to preinjury measures. To facilitate best practice, common neurocognitive, balance, and symptom report metrics used in concussion baseline testing merit examination relative to participant life stressors. Objective: The purpose of this study was to determine if life stressors are associated with college athlete neurocognitive function, postural control, and symptom scores at preseason baseline assessment. Design: All study variables were collected in a single laboratory session where athletes completed valid and reliable psychometrics as well as a computerized neurocognitive and balance assessments. Setting: Sports medicine research center on an American university campus. Participants: A convenience sample of 123 college student-athletes: 47 females (age = 18.9 [4.3] y) and 76 males (age = 19.4 [1.6] y). Main Outcome Measures: Participants were categorized into low, moderate, or high life stressors groups using scores from the Social Readjustment Rating Scale-Revised. Dependent variables included outcomes from the CNS Vitals Signs test, the Sensory Organization Test, and the graded symptom checklist indexing neurocognition, balance, and symptom severity, respectfully. Results: One-way analysis of variance revealed that the moderate life stressors group performed significantly worse than the low life stressors group on the baseline verbal memory domain of the CNS Vital Signs (F 2,119 = 3.28; P = .04) only. Conclusion: In the current college athlete sample, few baseline concussion assessment variables were found to be significantly associated with life stressors. Considering the clinical significance of these variables, psychological life stressors may not be a confounding factor in concussion evaluation.
Sean M. Burfeind and Nicole Chimera
Athletes participating in upper-extremity-dominant sports such as softball and volleyball are at increased risk for glenohumeral-joint pain and injury. For these athletes, an integral part of many injuryprevention and -rehabilitation programs includes improving joint proprioception. One way to measure joint proprioception is through the reproduction of joint angles, or joint-reposition sense (JRS). Kinesiology tape is purported to enhance neuromuscular feedback; therefore, it may influence JRS. However, conflicting findings and the lack of research in the upper extremity warrant further investigation.
To determine the effects of kinesiology tape on shoulder-joint proprioception by actively reproducing joint angles, or measurement of JRS.
Randomized controlled trial.
9 men and 7 women 24 ± 3 y old.
SpiderTech kinesiology tape precut Shoulder Spider was applied to the shoulder of participants block randomized to the experimental group, following product-specific instructions, to measure its influence on JRS compared with a control group.
Main Outcome Measurement:
JRS-error scores in shoulder flexion, extension, internal rotation, and external rotation (ER).
There was a significant interaction between groups pre- to postintervention resulting in decreased JRS errors in flexion (P = .04) and ER (P = .03) in the experimental compared with the control group. The 95% confidence intervals suggest a clinically relevant difference in the variability of JRS errors between postintervention movements for the experimental group in flexion and ER, such that the control group demonstrated much more variability in JRS errors than the experimental group.
After the application of kinesiology tape the JRS errors were smaller in flexion and ER. This may be of clinical significance in improving proprioception and thus improving joint stability. Additional research should determine the effectiveness of kinesiology tape in reducing joint injury.
Han-Kyu Park, Dong-Woo Kim, and Tae-Ho Kim
Context: Several factors, such as balance and respiration training programs, have been identified as contributing to a shooting performance. However, little is known about the benefits of these programs on the shooting records of adolescent air rifle athletes. Objective: The purpose of this study was to investigate whether balance and respiration training can contribute to the shooting performance required for adolescent air rifle shooting athletes. Design: Case-control study. Setting: Shooting range. Participants: A total of 21 adolescent air rifle athletes were recruited from the local school community and assigned to an experimental (n = 11; EG) or control (n = 10; CG) group. Intervention: The EG performed respiration and balance training for 30 minutes 3 times a week for 6 weeks, and the CG performed balance training only. Main Outcome Measures: Data were collected on the respiratory function, muscle activity, and shooting record before and after the 6-week intervention. Results: The forced vital capacity (FVC), forced expired volume in 1 second (FEV1), FEV1 as a percentage of FVC, peak expiratory flow, and maximum voluntary ventilation were significantly increased in the EG, and FEV1 as a percentage of FVC was significantly increased in the CG (P < .05). The FVC and peak expiratory flow postintervention were significantly different between the groups (P < .05). The activity of the right internal oblique (IO) and left IO muscles of the FVC were significantly different in the EG (P < .05). Within-group changes in right external oblique, right IO, and left IO of the maximum voluntary ventilation were significantly increased in the EG (P < .05). The right IO and left IO activity improved more significantly in the EG than CG (P < .05). There was no difference between the groups with respect to the shooting records. Conclusions: The clinical significance of this study is the balance and respiration training affected the respiration function capacity and muscle activity, but did not affect the shooting record. Nevertheless, these training are a potential approach method to improve athletes’ shooting record.