The purposes of this study were to (a) present a theoretical model to explain the methods by which individuals accommodate impact force in response to increases in an applied stressor, (b) use the model and a correlation procedure to classify a sample of individuals based on their observed response patterns, and (c) statistically evaluate the classification process. Ten participants performed landings from three heights while video and force platform data were being collected. Magnitudes of impact-force characteristics from ground reaction force and lower extremity joint moments were evaluated relative to changes in landing momentum. Correlation between impact force and landing momentum was used to classify participant responses into either a positive or negative biomechanical strategy, as defined by the model. Positive and negative groups were compared using the Mann-Whitney U test. Results indicated that all responses fit within the categories defined by the model. Some individuals preferred positive strategies while others preferred negative ones depending on the specific variable. Only one participant consistently exhibited the negative strategy for all variables. Positive and negative groups were determined to be statistically different, p ≤ 0.05, for 61% of the comparisons, suggesting actual differences between groups. The proposed model appeared robust and accounted for all responses in the current experiment. The model should be evaluated further using landing and other impact activities; it should be refined and used to help researchers understand individual impact-response strategies in order to identify those who may be at risk for impact related injuries.
C. Roger James, Barry T. Bates and Janet S. Dufek
Patti Syvertson, Emily Dietz, Monica Matocha, Janet McMurray, Russell Baker, Alan Nasypany, Don Reordan and Michael Paddack
Achilles tendinopathy is relatively common in both the general and athletic populations. The current gold standard for the treatment of Achilles tendinopathy is eccentric exercise, which can be painful and time consuming. While there is limited research on indirect treatment approaches, it has been proposed that tendinopathy patients do respond to indirect approaches in fewer treatments without provoking pain.
To determine the effectiveness of using a treatment-based-classification (TBC) algorithm as a strategy for classifying and treating patients diagnosed with Achilles tendinopathy.
11 subjects (mean age 28.0 ±15.37 y) diagnosed with Achilles tendinopathy.
Participants were evaluated, diagnosed, and treated at multiple clinics.
Main Outcome Measures:
Numeric Rating Scale (NRS), Disablement in the Physically Active Scale (DPA Scale), Victorian Institute of Sport Assessment–Achilles (VISA-A), Global Rating of Change (GRC), and Nirschl Phase Rating Scale were recorded to establish baseline scores and evaluate participant progress.
A repeated-measures ANOVA was conducted to analyze NRS scores from initial exam to discharge and at 1-mo follow-up. Paired t tests were analyzed to determine the effectiveness of using a TBC algorithm from initial exam to discharge on the DPA Scale and VISA-A. Descriptive statistics were evaluated to determine outcomes as reported on the GRC.
The results of this case series provide evidence that using a TBC algorithm can improve function while decreasing pain and disability in Achilles tendinopathy participants.
Mark Abel, James Hannon, David Mullineaux and Aaron Beighle
Current recommendations call for adults to be physically active at moderate and/or vigorous intensities. Given the popularity of walking and running, the use of step rates may provide a practical and inexpensive means to evaluate ambulatory intensity. Thus, the purpose of this study was to identify step rate thresholds that correspond to various intensity classifications.
Oxygen consumption was measured at rest and during 10 minute treadmill walking and running trials at 6 standardized speeds (54, 80, 107, 134, 161, and 188 m·min-1) in 9 men and 10 women (28.8 ± 6.8 yrs). Two observers counted the participants’ steps at each treadmill speed. Linear and nonlinear regression analyses were used to develop prediction equations to ascertain step rate thresholds at various intensities.
Nonlinear regression analysis of the metabolic cost versus step rates across all treadmill speeds yielded the highest R 2 values for men (R 2 = .91) and women (R 2 = .79). For men, the nonlinear analysis yielded 94 and 125 step·min-1 for moderate and vigorous intensities, respectively. For women, 99 and 135 step·min-1 corresponded with moderate and vigorous intensities, respectively.
Promoting a step rate of 100 step·min-1 may serve as a practical public health recommendation to exercise at moderate intensity.
Marieke J.G. van Heuvelen, Martin Stevens and Gertrudis I.J.M. Kempen
This study investigated differences in physical-fitness test scores between actively and passively recruited older adults and the consequences thereof for norm-based classification of individuals. Walking endurance, grip strength, hip flexibility, balance, manual dexterity, and reaction time were measured in participants age 57 years or older: 1 sample recruited through media announcements (passively recruited) and 1 sample recruited through personal contact (actively recruited). Classifications on a 5-point scale based on norms were cross-tabulated. Compared with the actively recruited sample, performance of the passively recruited sample was significantly better on all tests except, for women, hip flexibility and manual dexterity. Cross-tabulation of the 2 classifications showed that percentages of agreement varied from 27.4% to 87.4%. Cohen's Kappa varied from .11 to .84. Caution should be used when giving feedback on test performance and subsequently making physical activity recommendations if norms are based on the performance of passively recruited older adults.
Carolina F. Wilke, Felipe Augusto P. Fernandes, Flávio Vinícius C. Martins, Anísio M. Lacerda, Fabio Y. Nakamura, Samuel P. Wanner and Rob Duffield
in multifaceted conditions (eg, disease diagnosis) assists professionals in selecting the most effective intervention. 9 , 10 Similar methods in sport have reported; whereby the application of a statistical classification tool to 8 screening tests classified 28 professional rugby union players into
David R. Howell, Jessie R. Oldham, Melissa DiFabio, Srikant Vallabhajosula, Eric E. Hall, Caroline J. Ketcham, William P. Meehan III and Thomas A. Buckley
Gait impairments have been documented following sport-related concussion. Whether preexisting gait pattern differences exist among athletes who participate in different sport classifications, however, remains unclear. Dual-task gait examinations probe the simultaneous performance of everyday tasks (ie, walking and thinking), and can quantify gait performance using inertial sensors. The purpose of this study was to compare the single-task and dual-task gait performance of collision/contact and noncontact athletes. A group of collegiate athletes (n = 265) were tested before their season at 3 institutions (mean age= 19.1 ± 1.1 years). All participants stood still (single-task standing) and walked while simultaneously completing a cognitive test (dual-task gait), and completed walking trials without the cognitive test (single-task gait). Spatial-temporal gait parameters were compared between collision/contact and noncontact athletes using MANCOVAs; cognitive task performance was compared using ANCOVAs. No significant single-task or dual-task gait differences were found between collision/contact and noncontact athletes. Noncontact athletes demonstrated higher cognitive task accuracy during single-task standing (P = .001) and dual-task gait conditions (P = .02) than collision/contact athletes. These data demonstrate the utility of a dual-task gait assessment outside of a laboratory and suggest that preinjury cognitive task performance during dual-tasks may differ between athletes of different sport classifications.