Jason C. Dorman

Sport concussion knowledge base, clinical practises and needs for continuing medical education: a survey of family physicians and cross-border comparison

Context Evolving concussion diagnosis/management tools and guidelines make Knowledge Transfer and Exchange (KTE) to practitioners challenging. Objective Identify sports concussion knowledge base and practise patterns in two family physician populations; explore current/preferred methods of KTE. Design A cross-sectional study. Setting Family physicians in Alberta, Canada (CAN) and North/South Dakota, USA. Participants CAN physicians were recruited by mail: 2.5% response rate (80/3154); US physicians through a database: 20% response rate (109/545). Intervention/instrument Online survey. Main and secondary outcome measures Diagnosis/management strategies for concussions, and current/preferred KTE. Results Main reported aetiologies: sports/recreation (52.5% CAN); organised sports (76.5% US). Most physicians used clinical examination (93.8% CAN, 88.1% US); far fewer used the Sport Concussion Assessment Tool (SCAT1/SCAT2) and balance testing. More US physicians initially used concussion-grading scales (26.7% vs 8.8% CAN, p=0.002); computerised neurocognitive testing (19.8% vs 1.3% CAN; p<0.001) and Standardised Assessment of Concussion (SAC) (21.8% vs 7.5% CAN; p=0.008). Most prescribed physical rest (83.8% CAN, 75.5% US), while fewer recommended cognitive rest (47.5% CAN, 28.4% US; p=0.008). Return-to-play decisions were based primarily on clinical examination (89.1% US, 73.8% CAN; p=0.007); US physicians relied more on neurocognitive testing (29.7% vs 5.0% CAN; p<0.001) and recognised guidelines (63.4% vs 23.8% CAN; p<0.001). One-third of Canadian physicians received KTE from colleagues, websites and medical school training. Leading KTE preferences included Continuing Medical Education (CME) courses and online CME. Conclusions Existing published recommendations regarding diagnosis/management of concussion are not always translated into practise, particularly the recommendation for cognitive rest; predicating enhanced, innovative CME initiatives.

Comparison and utility of King-Devick and ImPACT® composite scores in adolescent concussion patients

UNLABELLED The King-Devick (KD) oculomotor test has recently been advocated for sideline diagnosis of concussion. Although visual processing and performance are often impaired in concussion patients, the utility of KD as a concussion diagnostic tool is not validated. PURPOSE To examine the diagnostic value of KD, by comparing KD with post-concussion symptom scale (PCSS) and ImPACT® composite scores. We hypothesized that KD would be correlated with visual motor speed/memory (VMS, VIS) and reaction time (RT), because all require cognitive visual processing. We also expected parallel changes in KD and PCSS across recovery. METHODS Thirty-five concussed individuals (12-19 y; 18 females, 17 males) were evaluated with PCSS, ImPACT® composite and KD scores over four clinical visits (V). RESULTS KD times improved with each visit (ΔV1-V2: 7.86±11.82; ΔV2-V3: 9.17 ± 11.07; ΔV3-V4: 5.30 ± 7.87 s) and paralleled improvements in PCSS (ΔV1-V2: 8.97 ± 20.27; ΔV2-V3: 8.69 ± 14.70; ΔV3-V4: 6.31 ± 7.71), RT (ΔV1-V2: 0.05 ± 0.21; ΔV2-V3: 0.09 ± 0.19; ΔV3-V4 0.03 ± 0.07) and VMS (ΔV1-V2: -5.27 ± 6.98; ΔV2-V3: -2.61 ± 6.48; ΔV3-V4: -2.35 ± 5.22). Longer KD times were associated with slower RT (r = 0.67; P<0.0001) and lower VMS (r = -0.70; P<0.0001), respectively. CONCLUSION Cognitive visual performance testing using KD has utility in concussion evaluation. Validation would further establish KD as an effective ancillary tool in longitudinal concussion management and research.

Tracking postural stability of young concussion patients using dual-task interference

OBJECTIVES This study examined the diagnostic benefit of using dual-task interference balance testing in young concussion patients and the longitudinal changes in postural stability that occur relative to other standard clinical assessments of concussion injury. DESIGN Longitudinal, case-control. METHODS Eighteen patients (16.6 (1.6)y) diagnosed with a concussion provided 22 separate ratings to characterize the severity of their current concussion-related symptoms and were evaluated for postural stability at each of four clinical visits. Twenty-six injury-free adolescents (17 (2.8)y) performed balance testing on two occasions, separated by ∼1 week. RESULTS There was a progressive decrease in self-reported symptoms from visit 1 to visit 4 (P<0.0001-0.001). A similar improvement occurred in postural stability, indicated by 95% ellipse area and velocity. However, the differences in ellipse area and velocity were significant only between visit 1 and the rest of the visits as a whole (P<0.0001-0.05). There was a significant difference between concussion patients and healthy, injury-free participants in ellipse area and velocity during visit 1. A group difference was also observed in ellipse area on visit 2, but only during the two balance tests that involved a concomitant secondary cognitive task. CONCLUSIONS Improvements in postural stability coincide with reductions in reported symptoms, though apparent recovery of these selected measures of postural stability seemingly occurs sooner. Because of the distinguishing time course of recovery indicated by dual-task interference balance testing, this type of balance testing assessment may be particularly valuable in evaluating integrated functional impairment and recovery in young concussion patients.

Analysis of Seated and Standing Triple Wingate Tests

Wilson, RW II, Snyder, AC, and Dorman, JC. Analysis of seated and standing triple Wingate tests. J Strength Cond Res 23(3): 868-873, 2009-Observations of athletes in seated and standing cycling positions in laboratory and field settings have led to the perception that they produce different outputs. The purpose of this study was to determine whether there are differences in power output and physiological responses between seated and standing positions of athletes during 3 consecutive Wingate tests. Seven (n = 7) elite-level speedskaters completed 3 × 30-second Wingate tests (resistance = 7.5% body weight) with 3.5 minutes of recovery between each test in both seated and standing positions. During the recovery period, athletes pedaled against no resistance in the seated position. Testing was randomized and separated by at least 48 hours. Power output, heart rate, blood lactate, and muscle oxygenation data were collected. Statistical analysis of comparable tests (i.e., seated Wingate test 1 [WinD1] compared with standing Wingate test 1 [WinU1]; WinD2:WinU2; WinD3:WinU3) revealed no significant differences between the seated and standing variables. Position during a short-duration maximal-effort exercise test on a stationary bike did not produce statistically different results in power, maximal heart rate, blood lactate, or muscle oxygenation. As no differences were detected between positions, practitioners can allow subjects to choose their position. Also, if a subject rises out of the seat during a “seated” test, this change may not affect the subjects physiological variables. However, transitioning from one position to the other during the test is not advised due to the possible chance of injury. It should be acknowledged that there may be reasons for stipulating one position over another (e.g., injuries, leg length).

Recurrent Heat Stroke in a Runner: Race Simulation Testing for Return to Activity.

Exertional heat stroke (EHS) occurs in distance runners and is a life-threatening condition. A 30-yr-old healthy recreational male distance runner (CR) collapsed at the 12-mile mark in two half marathon races 6 wk apart in fall 2009. In both episodes, CR was found on the ground confused, incoherent, sweaty, and warm to touch. The emergency medical team responded, and he was treated empirically for suspected EHS by cooling en route to the emergency department. In the emergency department, rectal temperatures were 40°C and 40.5°C for each episode, respectively. The first race start temperature was 16°C with 94% relative humidity (RH), and the second was 3°C, 75% RH. Heat tolerance test was within the normal range indicating low EHS risk. A race simulation test (environmental chamber, 25°C, 60% RH) at a treadmill pace of 10.5-12.9 km·h was stopped at 70 min coincident with a rectal temperature of 39.5°C. CRs body weight dropped 3.49 kg with an estimated sweat loss of 4.09 L and an estimated total sweat Na loss of 7610 mg. We recommended that he limit his runs to <1 h and replace salt and fluid during and (mostly) after activity, run with a partner, acclimate to heat before racing, and reduce his pace or stop at the first sign of symptoms. Race simulation testing should be considered in athletes with recurrent EHS to assist with the return-to-activity recommendation.

Oxygen Saturation in Right and Left Vastus Lateralis During Split Squat Exercise in Speed Skaters

Many athletes use resistance training to enhance muscular strength and endurance, with resistance determined as a percentage of a repetition maximum. However, the stress placed on the muscles is rarely determined. During a split squat exercise, it is essential to distribute weight equally in both legs to insure equal development. Near-infrared spectroscopy (NIRS) allows for noninvasive examination of muscle oxygenation during exercise. PURPOSE: The purpose of this study was to examine the right and left leg muscle oxygen usage during a typical split squat exercise workout to assess whether proper muscle emphasis could be determined. We hypothesized that muscle oxygen usage would be tractable by NIRS during resistance training exercise and that with elite athletes muscle oxygen usage would be similar in both legs during the split squat exercise. METHODS: Six (5 male and 1 female) National and International caliber speed skaters (aged 24 6 6 yrs) were monitored while performing a split squat training session. The procedure consisted of three sets of fifteen repetitions. A set consisted of fifteen repetitions with both the left and right legs forward. After each leg and between sets the athletes had a one minute rest period. The exercise protocol used was similar to the athletes’ regular workout. Percent oxygen saturation (StO2) of the right and left vastus lateralis muscles was measured continuously throughout the individual’s exercise. RESULTS: The results showed a large variation between subjects. Resting StO2 ranged from 96-53%, while the exercising StO2 ranged from 68-0%. With the left leg forward there was a large difference between subjects on which leg the emphasis was placed. Two placed greater emphasis on the left leg, three on the right leg and one subject put equal emphasis on both. When the right leg was forward, all subjects but one placed the emphasis on that right leg; the one placed greater emphasis on the left leg. CONCLUSION: Our results indicate that StO2 should be able to be used as an indicator of leg preference during the performance of a split squat training session. However, further research is needed on the usage of StO2 to monitor muscle utilization during resistance exercise. PRACTICAL SIGNIFICANCE: The use of muscle oxygenation to determine muscle usage during exercises such as the split squat has the potential to assist coaches and athletes to correctly critique and modify activity during a training session to maximize adaptations, especially at the elite level.