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PURPOSE: Recent anecdotal trends suggest a disproportionate number of head injuries in collegiate football players occur during preseason football camp. In warmer climates, this season also represents the highest risk for heat-related illness among collegiate football players. Because concussion and heat illnesses share many common symptoms, we need 1) to understand if environmental conditions, body temperature, and hydration status affect head impact biomechanics; and 2) to determine if an in-helmet thermistor could provide a valid measure of gastrointestinal temperature. METHODS: A prospective cohort of 18 Division I college football players (age, 21.1 ± 1.4 yr; height, 187.7 ± 6.6 cm; mass, 114.5 ± 23.4 kg). Data were collected during one control and three experimental sessions. During each session, the Head Impact Telemetry System recorded head impact biomechanics (linear acceleration, rotational acceleration, and severity profile) and in-helmet temperature. A wet bulb globe device recorded environmental conditions, and CorTemp™ Ingestible Core Body Temperature Sensors recorded gastrointestinal temperature. RESULTS: Our findings suggest that linear acceleration (P = 0.57), rotational acceleration (P = 0.16), and Head Impact Technology severity profile (P = 0.33) are not influenced by environmental or physiological conditions. CONCLUSIONS: We did not find any single or combination of predictors for impact severity. Rotational acceleration was approaching significance between our early experimental sessions when compared with our control session. More research should be conducted to better understand if rotational accelerations are a component of impact magnitudes that are affected due to changes in environmental conditions, body temperature, and hydration status.

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Multisport events continue to grow in popularity among recreational, amateur, and professional athletes around the world. This study aimed to determine the compounding effects of the initial run and cycling legs of an International Triathlon Union (ITU) Duathlon simulation on maximal oxygen uptake (VO2max), ventilatory threshold (VT) and running economy (RE) within a thermoneutral, laboratory controlled setting. Seven highly trained multisport athletes completed three trials; Trial-1 consisted of a speed only VO2max treadmill protocol (SOVO2max) to determine VO2max, VT, and RE during a single-bout run; Trial-2 consisted of a 10 km run at 98% of VT followed by an incremental VO2max test on the cycle ergometer; Trial-3 consisted of a 10 km run and 30 km cycling bout at 98% of VT followed by a speed only treadmill test to determine the compounding effects of the initial legs of a duathlon on VO2max, VT, and RE. A repeated measures ANOVA was performed to determine differences between variables across trials. No difference in VO2max, VT (%VO2max), maximal HR, or maximal RPE was observed across trials. Oxygen consumption at VT was significantly lower during Trial-3 compared to Trial-1 (p = 0.01). This decrease was coupled with a significant reduction in running speed at VT (p = 0.015). A significant interaction between trial and running speed indicate that RE was significantly altered during Trial-3 compared to Trial-1 (p < 0.001). The first two legs of a laboratory based duathlon simulation negatively impact VT and RE. Our findings may provide a useful method to evaluate multisport athletes since a single-bout incremental treadmill test fails to reveal important alterations in physiological thresholds. Key pointsDecrease in relative oxygen uptake at VT (ml·kg(-1)·min(-1)) during the final leg of a duathlon simulation, compared to a single-bout maximal run.We observed a decrease in running speed at VT during the final leg of a duathlon simulation; resulting in an increase of more than 2 minutes to complete a 5 km run.During our study, highly trained athletes were unable to complete the final 5 km run at the same intensity that they completed the initial 10 km run (in a laboratory setting).A better understanding, and determination, of training loads during multisport training may help to better periodize training programs; additional research is required.

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INTRODUCTION: Cardiopulmonary exercise testing (CPET), the gold standard of cardiopulmonary evaluation, is used to determine VO2 levels at different aerobic exercise training intensities; however, it may not be feasible to conduct CPET in all clinical settings. AIMS: To compare the heart rate reserve (HRR) and percent of 220-age methods for prescribing cycle ergometry exercise intensity using heart rate (HR) against the HRs obtained during a CPET in adults undergoing treatment for acute leukemia (AL). METHODS: In this exploratory study, part of a larger randomized controlled trial, 14 adults with AL completed CPET on a cycle ergometer with indirect calorimetry within 96 hr of admission to a cancer hospital to determine VO2peak and HR corresponding to low (40% VO2peak), moderate (60% VO2peak), and high (75% VO2peak) exercise intensities. Analyses of variance were used to compare estimated HR for each intensity level using the HRR and percent of 220-age methods with HR determined via VO2peak. RESULTS: HR corresponding to low-intensity exercise differed significantly across all three methods (p ≤ .05). No significant differences were observed between HR estimated via the percent of 220-age method and determined via VO2peak at moderate (100 ± 8 and 113 ± 24 bpm, p = .122) or high intensities (125 ± 10 and 123 ± 25 bpm, p = .994). CONCLUSION: In adults with AL, HR-based methods for defining aerobic exercise intensities should be used with caution. At low intensity, neither should be used, while at moderate and high intensities, the percent of 220-age equation might serve as an adequate substitute for CPET.

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The purpose of this study was to determine if performing a morning total-body resistance exercise workout affects explosive power in an afternoon session. The secondary goal was to assess the usefulness of the backward overhead shot throw (BOST) as a measure of explosive power in experienced thrower in the sport of athletics. Throwers (N = 14) performed 1 control and 1 experimental trial on separate days. The control consisted of BOST and a vertical jump (VJ) testing performed in the afternoon. For the experimental trial, the participants reported for a short resistance training session in the morning then repeating the BOST and VJ testing 4-6 hours later. The BOST distance (meters) and VJ peak power (watts) were correlated in both trials (r ∼ 0.64, p < 0.05). The BOST distance improved in experimental trial over control (p < 0.05), but VJ power failed to improve. The results indicate that a morning resistance exercise bout can improve competitive throwing performance later on the same day. The results also suggest that BOST may be a useful performance testing tool for throwers in the sports of athletics.

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CONTEXT: Neurocognitive testing is a recommended component in a concussion assessment. Clinicians should be aware of age and practice effects on these measures to ensure appropriate understanding of results. OBJECTIVE: To assess age and practice effects on computerized and paper-and-pencil neurocognitive testing batteries in collegiate and high school athletes. DESIGN: Cohort study. SETTING: Classroom and laboratory. PATIENTS OR OTHER PARTICIPANTS: Participants consisted of 20 collegiate student-athletes (age = 20.00 ± 0.79 years) and 20 high school student-athletes (age = 16.00 ± 0.86 years). MAIN OUTCOME MEASURE(S): Hopkins Verbal Learning Test scores, Brief Visual-Spatial Memory Test scores, Trail Making Test B total time, Symbol Digit Modalities Test score, Stroop Test total score, and 5 composite scores from the Immediate Post-Concussion Assessment and Cognitive Testing (ImPACT) served as outcome measures. Mixed-model analyses of variance were used to examine each measure. RESULTS: Collegiate student-athletes performed better than high school student-athletes on ImPACT processing speed composite score (F(1,38) = 5.03, P = .031) at all time points. No other age effects were observed. The Trail Making Test B total time (F(2,66) = 73.432, P < .001), Stroop Test total score (F(2,76) = 96.85, P = < .001) and ImPACT processing speed composite score (F(2,76) = 5.81, P = .005) improved in test sessions 2 and 3 compared with test session 1. Intraclass correlation coefficient calculations demonstrated values ranging from 0.12 to 0.72. CONCLUSIONS: An athlete's neurocognitive performance may vary across sessions. It is important for clinicians to know the reliability and precision of these tests in order to properly interpret test scores.

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Concussions sustained during college and professional football careers have been associated with both acute and chronic neurologic impairment. The contribution of subconcussive impacts to this impairment has not been adequately studied. Therefore, we investigated the relationship between subconcussive impacts and concussion history on clinical measures of neurologic function. Forty-six collegiate football players completed five clinical measures of neurologic function commonly employed in the evaluation of concussion before and after a single season. These tests included the Automated Neuropsychological Assessment Metrics, Sensory Organization Test, Standardized Assessment of Concussion, Balance Error Scoring System, and Graded Symptom Checklist. The Head Impact Telemetry (HIT) System recorded head impact data including the frequency, magnitude, and location of impacts. College football players sustain approximately 1,000 subconcussive impacts to the head over the course of a season, but for the most part, do not demonstrate any clinically meaningful changes from preseason to postseason on measures of neurologic function. Changes in performance were mostly independent of prior concussion history, and the total number, magnitude and location of sustained impacts over one season as observed R(2) values ranged between 0.30 and 0.35. Repetitive subconcussive head impacts over a single season do not appear to result in short-term neurologic impairment, but these relationships should be further investigated for a potential dose-response over a player's career.

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CONTEXT: Recent evidence has revealed deficiencies in the ability to divide attention after concussion. OBJECTIVE: To examine the effects of a single vs a dual task on cognition and balance in healthy subjects and to examine reliability of 2 dual-task paradigms while examining the overall feasibility of the tasks. DESIGN: Pretest-posttest experimental design. SETTING: Sports medicine research laboratory. PATIENTS: 30 healthy, recreationally active college students. INTERVENTION: Subjects performed balance and cognitive tasks under the single- and dual-task conditions during 2 test sessions 14 d apart. MAIN OUTCOME MEASURES: The procedural reaction-time (PRT) test of the Automated Neuropsychological Assessment Metrics (eyes-closed tasks) and an adapted Procedural Auditory Task (PAT; eyes-open tasks) were used to assess cognition. The NeuroCom Sensory Organization Test (SOT) and the Balance Error Scoring System (BESS) were used to assess balance performance. Five 2-way, within-subject ANOVAs and a paired-samples t test were used to analyze the data. ICCs were used to assess reliability across 2 test sessions. RESULTS: On the SOT, performance significantly improved between test sessions (F1,29 = 35.695, P < .001) and from the single to the dual task (F1,29 = 9.604, P = .004). On the PRT, performance significantly improved between test sessions (F1,29 = 57.252, P < .001) and from the single to the dual task (F1,29 = 7.673, P = .010). No differences were seen on the BESS and the PAT. Reliability across test sessions ranged from moderate to poor for outcome measure. CONCLUSIONS: The BESS appears to be a more reliable and functional tool in dual-task conditions as a result of its increased reliability and clinical applicability. In addition, the BESS is more readily available to clinicians than the SOT.

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Serial assessments of neurocognitive functioning in athletes with concussion are commonly used for return to play decisions. This study provides reliable change indices (RCIs) for computerized tests from 40 NCAA Division I collegiate athletes that suffered a sports-related concussion. The normative data that resulted from the RCIs and subsequent analyses of differences between improved and not improved athletes may aid both clinicians and researchers to assess whether observed change on neuropsychological measures is reliable change or change due simply to practice effects. Hence, the RCIs presented herein provide information that may be used judiciously by a clinician for assessing meaningful change.

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The purpose of this study was to examine performance differences between drafted and nondrafted athletes (N = 321) during the 2004 and 2005 National Football League (NFL) Combines. We categorized players into one of 3 groups: Skill, Big skill, and Linemen. Skill players (SP) consisted of wide receivers, cornerbacks, free safeties, strong safeties, and running backs. Big skill players (BSP) included fullbacks, linebackers, tight ends, and defensive ends. Linemen (LM) consisted of centers, offensive guards, offensive tackles, and defensive tackles. We analyzed player height and mass, as well as performance on the following combine drills: 40-yard dash, 225-lb bench press test, vertical jump, broad jump, pro-agility shuttle, and the 3-cone drill. Student t-tests compared performance on each of these measures between drafted and nondrafted players. Statistical significance was found between drafted and nondrafted SP for the 40-yard dash (P < 0.001), vertical jump (P = 0.003), pro-agility shuttle (P < 0.001), and 3-cone drill (P < 0.001). Drafted and nondrafted BSP performed differently on the 40-yard dash (P = 0.002) and 3-cone drill (P = 0.005). Finally, drafted LM performed significantly better than nondrafted LM on the 40-yard dash (P = 0.016), 225-lb bench press (P = 0.003), and 3-cone drill (P = 0.005). Certified strength and conditioning specialists will be able to utilize the significant findings to help better prepare athletes as they ready themselves for the NFL Combine.

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OBJECTIVE: It has been speculated that a theoretical injury threshold of 70 to 75 g may exist for concussions in football players. We aimed to investigate acute balance and neurocognitive performance after head impacts exceeding a theoretical injury threshold in the absence of both self-reported symptoms and a concussion diagnosis 24 hours before testing. METHODS: Forty-three Division I collegiate football players participated in this double-blind, repeated-measures study. Subjects participated in three test sessions (baseline, low impact, and high impact) separated by at least 2 weeks. The Head Impact Telemetry System (Simbex, Lebanon, NH) recorded real-time head impacts sustained during practices and games. The Automated Neuropsychological Assessment Metrics assessed neurocognitive performance. The NeuroCom Sensory Organization Test (NeuroCom International Inc., Clackamas, OR) assessed postural stability. The Graded Symptom Checklist evaluated symptom presence and severity in our participants. RESULTS: After the low-impact test session (<60 g), we observed improvements in the Math Processing (F(1, 26) = 9.797; P = 0.004), Matching to Sample (F(1, 26) = 6.504; P = 0.017), and Sternberg Procedure (F(1, 26) = 5.323; P = 0.030) Automated Neuropsychological Assessment Metrics test modules. Statistically significant differences were also observed after the high-impact test session (>90 g) with improvements in Math Processing (F(1, 22) = 16.629; P < 0.001), Procedural Reaction Time (F(1, 22) = 14.668; P < 0.001), and the total number of symptoms reported (F(1, 22) = 10.267; P = 0.004). Neurocognitive improvements were likely attributed to a learning effect. CONCLUSION: Our findings suggest that sustaining an impact greater than 90 g does not result in acute observable balance and neurocognitive deficits within 24 hours of sustaining the impact. Although previous studies have suggested a theoretical injury threshold, none have been founded on empirical data collected on the playing field in real-time. Future studies should consider the cumulative effects of impacts of varying magnitudes.

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OBJECTIVE: To examine effects of preseason baseline headache and posttraumatic headache (PTH) on neurocognitive function. DESIGN: Retrospective repeated measures study with headache groups formed regarding baseline headache score (0 = negative headache; 1-6 = positive headache) and day 1 postinjury headache score (0 = no headache; 1-2 = mild headache; 3-6 = moderate-severe headache). SETTING: Clinical athletic training setting and sports medicine research laboratory. PARTICIPANTS: High-school and collegiate athletes with a concussion. INDEPENDENT VARIABLES: Preseason baseline headache, PTH, test-day. MAIN OUTCOME MEASURES: A Graded Symptom Checklist (GSC) was used to assess symptoms. The Automated Neuropsychological Assessment Metrics (ANAM) and the Standardized Assessment of Concussion (SAC) were used to assess neuropsychological function and mental status. The Balance Error Scoring System (BESS) was used to assess postural stability. RESULTS: Both baseline headache groups displayed a higher symptom endorsement and higher symptom severity at day 1 postinjury and improved by day 7 postinjury. The positive headache group reported an even greater increase in symptom severity and presence (P < 0.05). ANAM revealed deficits in both groups 1 day postinjury. All PTH headache groups displayed a difference in symptom number and severity with the increase being magnified by headache severity (P < 0.05). Individuals reporting moderate-severe PTH displayed increased deficits subacutely but improved by 5-7 days postinjury on overall neuropsychological performance, reaction time, and working memory (P < 0.05). Deficits were observed for all ANAM measures except simple reaction time 1 (SRT 1) and match to sample subacutely and improved over time (P < 0.05). The SAC yielded an interaction (P < 0.05) for baseline headache. The BESS yielded no significant findings. CONCLUSIONS: Clinicians should consider headache when assessing concussion and during preseason baseline assessments because headache may affect symptom presence and other clinical measures of concussion.

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