Lauren C. Olmsted-Kramer and Jay Hertel
Phillip Gribble, Jay Hertel, Craig Denegar, and William Buckley
The SMART™ software system offers low-cost kinematic analysis through digitization of video from a single camera. The reliability and validity of this product have not been reported.
To assess the reliability and validity of the SMART software during a simple static task and dynamic task.
Test–retest to compare assumed neutral and goniometrically measured joint angles in the sagittal plane of the lower extremity.
7 in a static task, 16 young, physically active in a dynamic task.
Measurement error of the SMART system ranged from 0.29° ± 1.98° to 11.07° ± 1.77°. The interrater reliability (ICC2,1) values ranged from .60 to .92 for the static task and from .76 to .89 for the dynamic task.
Based on the results of both studies, the SMART system offers a low-cost alternative for reporting single-plane kinematics during an individual frame of video during static stances and slow dynamic tasks with strong reliability and reasonable validity.
Kyung-Min Kim, Christopher D. Ingersoll, and Jay Hertel
Focal ankle-joint cooling (FAJC) has been shown to increase Hoffmann (H) reflex amplitudes of select leg muscles while subjects lie prone, but it is unknown whether the neurophysiological cooling effects persist in standing.
To assess the effects of FAJC on H-reflexes of the soleus and fibularis longus during 3 body positions (prone, bipedal, and unipedal stances) in individuals with and without chronic ankle instability (CAI).
15 young adults with CAI (9 male, 6 female) and 15 healthy controls.
All subjects received both FAJC and sham treatments on separate days in a randomized order. FAJC was accomplished by applying a 1.5-L plastic bag filled with crushed ice to the ankle for 20 min. Sham treatment involved room-temperature candy corn.
Main Outcome Measures:
Maximum amplitudes of H-reflexes and motor (M) waves were recorded while subjects lay prone and then stood in quiet bipedal and unipedal stances before and immediately after each treatment. Primary outcome measures were Hmax:Mmax ratios for the soleus and fibularis longus. Three-factor (group × treatment condition × time) repeated-measures ANOVAs and Fisher LSD tests were performed for statistical analyses.
Significant interactions of treatment condition by time for prone Hmax:Mmax ratios were found in the soleus (P = .001) and fibularis longus (P = .003). In both muscles, prone Hmax:Mmax ratios moderately increased after FAJC but not after sham treatment. The CAI and healthy groups responded similarly to FAJC. In contrast, there were no significant interactions or main effects in the bipedal and unipedal stances in either muscle (P > .05).
FAJC moderately increased H-reflex amplitudes of the soleus and fibularis longus while subjects were prone but not during bipedal or unipedal standing. These results were not different between groups with and without CAI.
Jennifer M. Medina McKeon, Craig R. Denegar, and Jay Hertel
The purpose of this study was to formulate a predictive equation to discriminate males from females using static and dynamic lower extremity (LE) alignments. Twenty-four healthy adults volunteered to participate. Three-dimensional motion analysis was used to assess the kinematics of the right hip and knee during two functional tasks. Six measures of static LE alignment were also performed. Statistical comparisons were made between males and females for all variables. Static and dynamic variables that were significantly different by sex were entered into separate discriminant analyses for each task. The resulting equations were each able to correctly predict 87% of the subjects by sex. Fifty-eight percent and 55% of the variance was explained by sex for the vertical jump and plant & jump, respectively. The frontal plane hip angle was the best predictor of sex for both tasks. While there were statistically significant differences between the sexes for static measures of LE alignment, kinematic measures were better at discriminating between sexes.
Stephan G. Bodkin, Jay Hertel, and Joseph M. Hart
Context: Individuals following anterior cruciate ligament reconstruction (ACLR) demonstrate altered postural stability and functional movement patterns. It is hypothesized that individuals following ACLR may compensate with sensory adaptations with greater reliance on visual mechanisms during activities. It is unknown if visual compensatory strategies are implemented to maintain postural stability during functional tasks. Objective: To examine visual gaze accuracy during a single-leg balance task in individuals following ACLR compared with healthy, active controls. Design: Case control. Setting: Controlled laboratory. Participants: A total of 20 individuals (10 ACLR and 10 healthy controls) participated in the study. Data Collection and Analysis: Visual gaze patterns were obtained during 20-second single-leg balance trials while participants were instructed to look at presented targets. During the Stationary Target Task, the visual target was presented in a central location for the duration of the trial. The Moving Target Task included a visual target that randomly moved to 1 of 9 target locations for a period of 2 seconds. Targets were stratified into superior, middle, and inferior levels for the Moving Target Task. Results: The Stationary Target Task demonstrated no differences in visual error between groups (P = .89). The Moving Target Task demonstrated a significant interaction between group and target level (F 2,36 = 3.76, P = .033). Individuals following ACLR demonstrated greater visual error for the superior targets (ACLR = .70 [.44] m, healthy = .41 [.21] m, Cohen d = 0.83 [0.06 to 1.60]) and inferior targets (ACLR = .68 [.25] m, healthy = .33 [.16] m, Cohen d = 1.67 [0.81 to 2.52]). Conclusion: Individuals following ACLR demonstrate greater visual error during settings of high or low visual stimuli compared with healthy individuals to maintain single-limb postural stability. This population may rely on visual input to compensate for the somatosensory changes following injury.
Jennifer E. Earl, Jay Hertel, and Craig R. Denegar
Dynamic malalignment (DM), abnormal muscle activation, and static malalignments all might lead to patellofemoral pain (PFP) but have not been examined using a multifactorial approach.
To determine which measures of static malalignment, DM, and muscle-onset times best predict PFP.
Design and Setting:
2 groups (PFP and uninjured) of 16 subjects each.
EMG and 3-D kinematic data were recorded during a step-down. Five static-alignment assessments were performed.
Three discriminant analyses using injury as the grouping variable and static measures, joint angles, and EMG onsets as the predictor variables. A final combined discriminant analysis using the most predictive variables from each set.
The static-alignment discriminant function was most predictive (81.3% correct), followed by the kinematic (69%) and the EMG (67%) functions. The final discriminant function included iliotibial-band flexibility, navicular drop, pronation, knee flexion, hip adduction, gluteus medius, and vastus medialis obliquus onset time and correctly classified 92.3% of PFP subjects.
PFP can most accurately be predicted when multiple measures of lower extremity function are considered together.
Caroline Lisee, Lindsay Slater, Jay Hertel, and Joe M. Hart
Context: Strength, functional performance, and limb symmetry are common objective clinical assessments used by clinicians to guide safe return to physical activity following injury. Population-specific unilateral limb outcomes or estimates of limb symmetry of these assessments should be established. Objective: To compare lower-extremity strength, functional performance, and limb symmetry in healthy participants based on sex and level of activity. Design: Descriptive laboratory study. Setting: Laboratory. Participants: A total of 117 healthy participants (72 males and 45 females; mass = 73.67 [13.60] kg, height = 1.76 [0.12] m, and age = 21.44 [2.92] y) without history of injury within 6 months were included. Interventions: Participants completed isokinetic concentric and isometric knee extension and flexion strength tasks at 90°/s, 180°/s, and 90°, respectively, and 4 hop tasks (single, cross-over, triple, and 6-m timed) during 1 session. Groups were separated by sex (male and female) and activity level (athlete and nonathlete). Participants rostered on National Collegiate Athletic Association (NCAA) Division I (DI) teams were considered as athletes, and non-NCAA DI healthy, uninjured participants were considered as nonathletes. Main Outcome Measures: Limb symmetry index (LSI), maximal voluntary isometric contraction (N·m/kg), peak torque (N·m/kg), average power (N·m/s), distance (m), and time hopped (s) were assessed. LSI was calculated by dividing the lower limb outcome by the higher limb outcome of the nondominant or dominant limb. Group differences were assessed through Mann–Whitney U tests and Cohen’s d effect sizes for all comparisons. Results: LSI differences did not exist between groups. Mean LSIs for all participants ranged between 83.52% (12.54%) and 96.16% (3.82%). On average, males were stronger (range: d = 0.63–1.54), hopped farther (range: d = 1.52–1.63), and hopped faster (range: d = 1.67–1.68) than females. On average, some strength differences existed between athletes and nonathletes, but athletes hopped farther (range: d = 0.71–0.82) and faster (range: d = 0.87–0.88) than nonathletes. Conclusions: Unilateral limb strength and functional performance outcomes differ between sex and activity level, but not limb symmetry. These differences may be important for a clinician’s understanding of normative values of common return-to-play assessment tasks.
Revay O. Corbett, Tyler R. Keith, and Jay Hertel
Context: Patient-reported outcome measures (PROs) and functional performance tests are recommended in the National Athletic Trainers’ Association’s position statement on the prevention and management of ankle sprains during the return-to-play process. Evaluating perceived confidence may be another valuable method to evaluate an athlete’s readiness to return-to-play following an ankle sprain. Objective: To evaluate the relationship between PROs and perceived confidence when performing functional performance tasks in high school athletes with a history of ankle sprain. Design: Descriptive study. Setting: Public high school. Patients or Other Participants: A total of 25 high school student-athletes (6 males and 19 females, age 16.2 [1.1] y, height 169.3 [7.7] cm, mass 63.2 [9.8] kg). Intervention(s): None. Main Outcome Measures: The Cumberland Ankle Instability Tool, visual analog scale (VAS) for pain, Identification of Functional Ankle Instability, and Tampa Scale of Kinesiophobia-11 were completed by all participants. Participants then completed the weight-bearing lunge test; star excursion balance test; lateral, up–down, and triple hop tests; the single-leg vertical jump; and Southeast Missouri agility test and were asked to report their confidence in completing each task using a VAS with anchors of “no confidence” and “complete confidence.” Pearson r correlations were calculated between the PROs and the confidence VAS scores of the functional tests. Results: Moderate to strong negative correlations were identified between pain VAS measures and confidence VAS measures for all functional tests except the star excursion balance test and vertical jump. Moderate negative correlations were found between Tampa Scale of Kinesiophobia-11 scores and perceived confidence during the star excursion balance test and vertical jump. Finally, a moderate positive correlation was identified between Cumberland Ankle Instability Tool scores and perceived confidence measures during the Southeast Missouri agility test. Conclusions: High school athletes with a history of ankle sprain demonstrated significant correlations between several PROs and perceived confidence during various functional performance tests. The value of perceived confidence measures when making return-to-play decisions after ankle sprains warrants further investigation.
Jay Hertel, S. John Miller, and Craig R. Denegar
To estimate intratester and intertester reliability and learning effects during the Star Excursion Balance Tests (SEBTs).
A university athletic training research laboratory.
Sixteen healthy volunteers with no history of balance disorders or significant lower extremity joint pathology.
Length of excursion was measured manually for each trial.
ICCs for intratester reliability were .78–.96 on day 1 and 32–.96 on day 2. ICCs for intertester reliability were .35–.84 on day 1 and .81–.93 on day 2. Significant learning effects were identified for 4 of the 8 tests.
Estimates of intratester and intertester reliability were high, but adequate practice trials should be performed before taking baseline measures.
John Goetschius, Mark A. Feger, Jay Hertel, and Joseph M. Hart
Context: Measurements of center-of-pressure (COP) excursions during balance are common practice in clinical and research settings to evaluate adaptations in postural control due to pathological or environmental conditions. Traditionally measured using laboratory force plates, pressure-mat devices may be a suitable option for clinicians and scientist to measure COP excursions. Objective: Compare COP measures and changes during balance between MatScan® pressure mat and force plate. Design: Validation study. Setting: Laboratory. Participants: 30 healthy, young adults (19 female, 11 male, 22.7 ± 3.4 y, 70.3 ± SD kg, 1.71 ± 0.09 m). Main Outcomes: COP excursions were simultaneously measured using pressure-mat and force-plate devices. Participants completed 3 eyes-open and 3 eyes-closed single-leg balance trials (10 s). Mean of the 3 trials was used to calculate 4 COP variables: medial-lateral and anterior-posterior excursion, total distance, and area with eyes open and eyes closed. Percent change and effect sizes were calculated between eyes-open to eyes-closed conditions for each variable and for both devices. Results: All COP variables were highly correlated between devices for eyes-open and eyes-closed conditions (all r > .92, P < .001). Bland-Altman plots suggest the pressure-mat COP measurements were smaller than those of the force-plate, and the differences between devices appeared to increase as the measurement magnitude increased. Percent change in COP variables was highly correlated between devices (r > .85, P < .001). Cohen d effect sizes between eyes-open and eyes-closed were all large (d > 2.25) and similar in magnitude between devices. Conclusion: COP measures were correlated between devices, but values tended to be smaller using the pressure mat. The pressure mat and force plate detected comparable magnitude changes in COP measurements between eyes-open and eyes-closed. Pressure mats may provide a viable option for detecting large magnitude changes in postural control during short-duration testing.