Influential Factors and Preliminary Reference Data for a Clinically Feasible, Functional Reaction Time Assessment: The Standardized Assessment of Reaction Time.

CONTEXT: Clinical reaction-time (RT) measures are frequently used when examining patients with concussion but do not correlate with functional movement RT. We developed the Standardized Assessment of RT (StART) to emulate the rapid cognitive demands and whole-body movement needed in sport. OBJECTIVE: To assess StART differences across 6 cognitive-motor combinations, examine potential demographic and health history confounders, and provide preliminary reference data for healthy collegiate student-athletes. DESIGN: Prospective, cross-sectional study. SETTING: Clinical medicine facilities. PATIENTS OR OTHER PARTICIPANTS: A total of 89 student-athletes (56 [62.9%] men, 33 [37.1%] women; age = 19.5 ± 0.9 years, height = 178.2 ± 21.7 cm, mass = 80.4 ± 24 kg; no concussion history = 64 [71.9%]). MAIN OUTCOME MEASURE(S): Student-athletes completed health history questionnaires and StART during preseason testing. The StART consisted of 3 movements (standing, single-legged balance, and cutting) under 2 cognitive states (single task and dual task [subtracting by 6's or 7's]) for 3 trials under each condition. The StART trials were calculated as milliseconds between penlight illumination and initial movement. We used a 3 × 2 repeated-measures analysis of variance with post hoc t tests and 95% CIs to assess StART cognitive and movement differences, conducted univariable linear regressions to examine StART performance associations, and reported StART performance as percentiles. RESULTS: All StART conditions differed (P ≤ .03), except single-task standing versus single-task single-legged balance (P = .36). Every 1-year age increase was associated with an 18-millisecond (95% CI = 8, 27 milliseconds) slower single-task cutting RT (P < .001). Female athletes had slower single-task (15 milliseconds; 95% CI = 2, 28 milliseconds; P = .02) and dual-task (28 milliseconds; 95% CI = 2, 55 milliseconds; P = .03) standing RT than male athletes. No other demographic or health history factors were associated with any StART condition (P ≥ .056). CONCLUSIONS: The StART outcomes were unique across each cognitive-motor combination, suggesting minimal subtest redundancy. Only age and sex were associated with select outcomes. The StART composite scores may minimize confounding factors, but future researchers should consider age and sex when providing normative data.

Relationship and Latent Factors Between Clinical Concussion Assessments and the Functional Standardized Assessment of Reaction Time (StART).

OBJECTIVE: To examine the relationships and latent factors within the Standardized Assessment of Reaction Time (StART), and between StART and current clinical assessments. DESIGN: Cross-sectional study. SETTING: Clinical medicine facility. PARTICIPANTS: Eighty-nine healthy collegiate student-athletes (63% male, age: 19.5 ± 0.9 years, 28% ≥1 concussion history). ASSESSMENT OF RISK FACTORS: Student-athletes completed StART and clinical assessments during preinjury testing. MAIN OUTCOME MEASURES: Standardized Assessment of Reaction Time consisted of 3 conditions (standing, single-leg balance, cutting) under 2 cognitive states (single task and dual task) for 3 trials each condition. Clinical assessments were the Sport Concussion Assessment Tool (SCAT) symptom checklist, Standardized Assessment of Concussion (SAC), tandem gait (single task and dual task), and Immediate PostConcussion Assessment and Cognitive Testing (ImPACT). We used Pearson- r correlation coefficients and exploratory factor analysis (EFA) to examine relationships and latent factors between StART and clinical assessments. RESULTS: Null to moderate correlations presented among the StART outcomes (r range: 0.06-0.70), and null to small correlations between StART and clinical assessments (r range: -0.16 to 0.34). The three-factor EFA for solely StART explained 70.6% total variance: functional movement (cutting), static dual-task (standing and single-leg balance), and static single task (standing and single-leg balance). The five-factor EFA for StART and clinical assessments explained 65.8% total variance: gait (single-task and dual-task tandem gait), functional movement (StART single-task and dual-task cutting), static dual-task (StART standing, single-leg balance), neurocognitive (ImPACT verbal memory, visual memory, visual-motor speed), and static single task (StART standing, single-leg balance). No other outcomes met the factor loading threshold. CONCLUSIONS: StART displayed 3 distinct categories and had minimal redundancy within its subtests. StART did not meaningfully correlate with clinical assessments, suggesting that StART provides unique information by examining more functional, reactive movement.

Association Between Collision Sport Career Duration and Gait Performance in Male Collegiate Student-Athletes.

BACKGROUND: Investigations of estimated age of first exposure to repetitive head impacts from collision and contact sports have shown no associations with neurocognitive or neurobehavioral function at the collegiate level, but the effect of career duration may be a more comprehensive factor. Understanding whether longer career duration influences gait performance would provide insights into potential neurological impairment. PURPOSE: To examine the relationship between career duration of collision sports and single/dual-task gait performance in collegiate student-athletes. STUDY DESIGN: Cross-sectional study; Level of evidence, 3. METHODS: We recruited 168 male student-athletes from collision sports: football, lacrosse, ice hockey, and wrestling (mean ± SD age, 19.2 ± 1.3 years; height, 184.5 ± 7.2 cm; mass, 94.3 ± 15.9 kg; estimated age of first exposure, 8.6 ± 3.1 years; career duration, 10.6 ± 3.0 years). All participants completed a baseline single- and dual-task gait assessment before the start of their athletic season. Inertial measurement units were used to measure gait speed and stride length. During the dual task, participants were asked to perform working memory cognitive tasks while walking. The dependent variables were single/dual-task gait speed and stride length, cognitive accuracy, and dual-task cost. The relationship between career duration, analyzed as a continuous variable, and the dependent variables was analyzed using a linear regression. RESULTS: There were no significant associations between career duration and single-task gait speed (1.16 ± 0.16 m/s; ß = -0.004; P = .35; 95% CI = -0.012 to 0.004; η2 = 0.005) or dual-task gait speed (1.02 ± 0.17 m/s; ß = -0.003; P = .57; 95% CI = -0.011 to 0.006; η2 = 0.002). There were also no significant associations between career duration and single/dual-task stride length, cognitive accuracy, or dual-task cost. CONCLUSION: Career duration among collegiate collision sport athletes was not associated with single- or dual-task gait performance, suggesting that a greater exposure to repetitive head impacts is not detrimental to dynamic postural control at the college level. However, the effects of diminished gait performance over the lifetime remain to be elucidated.

Proteomic Discovery of Noninvasive Biomarkers Associated With Sport-Related Concussions.

BACKGROUND AND OBJECTIVES: Sport-related concussions affect millions of individuals across the United States each year, and current techniques to diagnose and monitor them rely largely on subjective measures. Our goal was to discover and validate objective, quantifiable noninvasive biomarkers with the potential to be used in sport-related concussion diagnosis. METHODS: Urine samples from a convenience series of healthy control collegiate athletes who had not sustained a concussion and athletes who sustained a concussion as diagnosed by a sports medicine physician within 7 days were collected prospectively and studied. Participants also completed an instrumented single-task gait analysis as a functional measure. Participants were recruited from a single collegiate athletic program and were ≥18 years of age and were excluded if they had a concomitant injury, active psychiatric conditions, or preexisting neurologic disorders. Using Tandem Mass Tags (TMT) mass spectroscopy and ELISA, we identified and validated urinary biomarkers of concussion. RESULTS: Forty-eight control and 47 age- and sex-matched athletes with concussion were included in the study (51.6% female, 48.4% male, average age 19.6 years). Participants represented both contact and noncontact sports. All but 1 of the postconcussion participants reported experiencing symptoms at the time of data collection. Insulin-like growth factor 1 (IGF-1) and IGF binding protein 5 (IGFBP5) were downregulated in the urine of athletes with concussions compared to healthy controls. Multivariable risk algorithms developed to predict the probability of sport-related concussion showed that IGF-1 multiplexed with single-task gait velocity predicts concussion risk across a range of postinjury time points (area under the curve [AUC] 0.786, 95% confidence interval [CI] 0.690-0.884). When IGF-1 and IGFBP5 are multiplexed with single-task gait velocity, they accurately distinguish between healthy controls and individuals with concussion at acute time points (AUC 0.835, 95% CI 0.701-0.968, p < 0.001). DISCUSSION: These noninvasive biomarkers, discovered in an objective and validated manner, may be useful in diagnosing and monitoring sport-related concussions in both acute phases of injury and several days after injury. TRIAL REGISTRATION INFORMATION: ClinicalTrials.gov Identifier: NCT02354469 (submitted February 2015, first patient enrolled August 2015). CLASSIFICATION OF EVIDENCE: This study provides Class III evidence that urinary IGF-1 and IGFBP5 multiplexed with single-task gait velocity may be useful in diagnosing sport-related concussion.

Evaluation of a Pharmacist Managed Telephone Pain Clinic for Neuropathy Treatment.

Pain is prevalent in our society, affecting more than a quarter-million U.S. adults and leading to poor patient outcomes. At the Veteran's Affairs San Diego Healthcare System (VASDHS), a Telephone Pain Clinic (TPC) was developed to improve these outcomes. The purpose of this study was to evaluate the effectiveness of TPC in improving neuropathic pain. A retrospective cohort study was conducted at the VASDHS comparing pre- and post- self-rated Numeric Rating Scale (NRS-11), an 11-point scale from 0 to 10 with 0 equaling no pain and 10 equaling most severe pain. Patients were included if they were referred and enrolled to the TPC for neuropathic pain. They were excluded if they were co-managed by another pain provider or were referred for any other pain conditions. A total of 830 TPC patients were screened between January 2008 to December 2009 and 52 patients met criteria. Patients who participated in the clinic were found to have a significant 0.83 (p = 0.014) reduction in mean pain score from baseline (6.62, SD 1.96) to discharge (5.79, SD 2.49). At discharge, pain medications that were increased were use of serotonin and norepinephrine reuptake inhibitors (SNRIs), pregabalin, and capsaicin. Management by the TPC showed promise and trends toward reducing pain experienced by patients with diabetic neuropathy, fibromyalgia, or postherpetic neuralgia. The TPC also may be more effective in maximizing evidenced-based pharmacotherapy for neuropathic pain, suggesting expertise by pharmacist clinical specialists.

Dual-Task Gait Recovery after Concussion among Female and Male Collegiate Athletes.

PURPOSE: Few studies have investigated recovery between sexes using objective outcome measures. Our purpose was to examine the independent association between biological sex and recovery of postconcussion gait among collegiate athletes. METHODS: We evaluated participants with a diagnosed concussion <7 d postinjury, and approximately 1.5 months and 3.5 months postinjury. Participants completed a single/dual-task gait evaluation and symptom inventory. During dual-task trials, they completed a mental task (backward subtraction, spelling, or month recitation). The primary outcome measure was height-adjusted gait velocity recovery, defined as achieving normal gait velocity using established values: >0.56 and >0.50 gait velocity (m·s)/height (m) under single and dual-task conditions, respectively. We used a multivariable Cox proportional hazard model to identify associations between sex and dual-task recovery, controlling for age, concussion history, symptom severity, and loss of consciousness at the time of injury. RESULTS: Ninety-four individuals participated in the study: 47 (50%) were female athletes (mean age = 20.1, SD = 1.3 yr) and 47 (50%) were male athletes (mean age = 20.3, SD = 1.3 yr). Sex was not independently associated with height-adjusted single-task gait velocity recovery after controlling for potential confounders (hazard ratio = 1.62, 95% confidence interval = 0.87-3.01). However, male sex was independently associated with longer dual-task gait recovery time after controlling for potential confounders (hazard ratio = 2.43, 95% confidence interval = 1.11-5.35). CONCLUSION: Male athletes required a longer duration of time after concussion to achieve dual-task gait recovery than female athletes. Thus, functional dual-task abilities after concussion may be affected differentially by sex and should be accounted for within individualized concussion management strategies.

Exercise in the first week following concussion among collegiate athletes: Preliminary findings.

OBJECTIVES: Our purpose was to examine the association between exercise after concussion with symptom severity, postural control, and time to symptom-resolution. DESIGN: Longitudinal cohort. METHODS: Collegiate athletes (n = 72; age = 20.2 ±â€¯1.3 years; 46% female) with concussion completed a symptom questionnaire at initial (0.6 ±â€¯0.8 days post-injury) and follow-up (2.9 ±â€¯1.4 days post-injury) evaluations, and a postural control assessment at follow-up. Participants were grouped into those who exercised in between the time of injury and the follow-up evaluation and those who did not. Decisions regarding post-concussion exercise were made by a sports medicine team consisting of a single team physician and athletic trainers. RESULTS: Thirteen athletes were not included in the current study, resulting in an 85% response rate. Thirteen of the athletes who completed the study exercised between evaluations (18%). There was no symptom resolution time difference between groups (median = 13 [IQR = 7-18] days vs. 13 [7-23] days; p = 0.83). Symptom ratings were similar between groups at the acute post-injury assessment (median PCSS = 18.5 [7.5-26] vs. 17 [14-40]; p = 0.21), but a main effect of group after adjusting for time from injury to assessment indicated the exercise group reported lower symptom severity than the no exercise group across both assessments (p = 0.044). The dual-task gait speed of the exercise group was higher than the no exercise group (0.90 ±â€¯0.15 vs. 0.78 ±â€¯0.16 m/s; p = 0.02). CONCLUSIONS: Athletes who were recommended aerobic exercise after concussion did not have worse outcomes than those who were not. Exercise within the first week after concussion does not appear to be associated with detrimental clinical outcomes.

Myocardial Adaptations to Competitive Swim Training.

PURPOSE: Swim training is performed in the prone or supine position and obligates water immersion, factors that may augment cardiac volume loading more than other endurance sports. At present, prospective data defining the cardiac responses to swim training are lacking. We therefore studied myocardial adaptations among competitive swimmers to establish a causal relationship between swim training and left ventricular (LV) remodeling. METHODS: Collegiate swimmers were studied before and after a 90-d period of training intensification. Transthoracic echocardiography was used to examine LV structural and functional adaptations under resting conditions and during an acute LV afterload challenge generated by isometric handgrip testing (IHGT). A sedentary control population was identically studied with IHGT. RESULTS: In response to a discrete period of swim training intensification, athletes (n = 17, 47% female, 19 ± 0.4 yr old) experienced eccentric LV remodeling, characterized by proportionally more chamber dilation than wall thickening, with attendant enhancements of resting LV systolic (LV twist) and diastolic (early and late phase tissue velocities) function. Compared with baseline and controls, athletes posttraining demonstrated greater systolic twist impairment during IHGT. However, training-induced LV dilation coupled with gains in diastolic function offsets this acquired systolic susceptibility to acute afterload, resulting in the relative preservation of stroke volume during IHGT. CONCLUSION: Swim training, a sport characterized by unique cardiac loading conditions, stimulates eccentric LV remodeling with the concomitant augmentation of systolic twist and diastolic relaxation. This volume-mediated cardiac remodeling appears to result in greater systolic susceptibility to acute afterload challenge. Further work is required to establish how training-induced changes in function translate to human performance and whether these are accompanied by physiologic trade-offs with relevance to common forms of heart disease.

Identification of Post-Concussion Dual-Task Gait Abnormalities Using Normative Reference Values.

Our purpose was to identify the rate of abnormal single-task and dual-task gait performance acutely post-concussion relative to uninjured controls using previously established normative reference values. We examined athletes with a concussion (n=54; mean age=20.3±1.1 years of age, 46% female, tested 2.9±1.5 days post-injury) and healthy controls tested during their preseason baseline examination (n=60; 18.9±0.7 years of age, 37% female). Participants completed an instrumented single/dual-task gait evaluation. Outcome variables included average walking speed, cadence, and step length. A significantly greater number of those with concussion walked with abnormal dual-task gait speed compared to the control group (56% vs. 30%; p= 0.008). After adjusting for potential confounding variables (age, concussion history, symptom severity, and sleep), concussion was associated with lower dual-task gait speed (ß=-0.150; 95% CI=-0.252,-0.047), cadence (ß= -8.179; 95% CI=-14.49,-1.871), and stride length (ß=-0.109; 95% CI=-0.204,-0.014). Although group analyses indicated that those with a concussion performed worse on single-task and dual-task gait compared to controls, a higher rate of abnormal gait was detected for the concussion group compared to the control group for dual-task gait speed only. Dual-task gait speed, therefore, may be considered as a measure to compare against normative values to detect post-concussion impairments.

Self-reported sleep duration affects tandem gait, but not steady-state gait outcomes among healthy collegiate athletes.

BACKGROUND: Sleep deficits are associated with motor and cognitive function deficits, even in the absence of a recent concussion. RESEARCH QUESTION: Does the amount of self-reported sleep prior to pre-season concussion testing affect single-task and dual-task instrumented steady-state gait and timed tandem gait test performance? METHODS: One hundred and fourteen healthy collegiate athletes (mean age 18.8 ±â€¯0.7 years; 60% female) reported the amount of sleep they received during the prior night and completed a timed tandem gait test and an instrumented assessment of steady-state gait in both single-task and dual-task conditions. Outcome variables included spatio-temporal gait parameters during steady-state gait, best and mean tandem gait times, and cognitive test accuracy. RESULTS: Participants who reported sleeping <7 h of sleep during the night prior to testing (n = 62) had significantly longer tandem gait times in single-task and dual-task conditions (11.1 ±â€¯2.2 vs. 10.1 ±â€¯2.0 s and 14.5 ±â€¯4.3 vs. 12.3 ±â€¯2.6 s, respectively; p = .009) compared to those who reported sleeping ≥7 h (n = 52). No significant differences between groups were observed for spatio-temporal steady-state gait variables or for cognitive test accuracy. SIGNIFICANCE: Self-reported sleep duration may be associated with baseline testing tandem gait performance. Thus, as sleep can play a role in motor abilities, clinicians may consider interpreting tandem gait performance in light of sleep duration during the night prior to testing.

The utility of instrumented dual-task gait and tablet-based neurocognitive measurements after concussion.

OBJECTIVES: Quantitative and non-invasive measurements acquired by neurocognitive or gait evaluations are useful concussion management components. Emerging technology has allowed for the development of portable and objective tests which may be potentially useful across many settings where evaluations take place. Our aim was to examine the association between instrumented dual-task gait and tablet-based neurocognitive outcome variables with an acute concussion. DESIGN: A total of 59 collegiate athletes were identified and tested within 5days of concussion (n=18, 50% female, 20±1years of age) or as a part of a baseline examination (n=41, 29% female, 19±1years of age). METHODS: Participants completed an instrumented dual-task gait evaluation and a tablet-based neurocognitive evaluation. Outcome variables were compared with t-tests, and a multivariable logistic regression model was constructed to identify the association between the presence of a concussion and test performance. RESULTS: Compared with controls, participants with concussion reported significantly more severe symptoms (PCSS=19.1±15.2 vs. 4.1±6.3; p<0.001), walked significantly slower during dual-task conditions (87.7±10.4cm/s vs. 98.1±15.4cm/s; p=0.01), and responded with significantly slower simple reaction times (305.2±32.4ms vs. 275.4±22.1ms; p<0.001). After adjusting for the effect of potential confounding variables, these three variables (more severe symptoms, slower walking speed, and slower reaction time) remained independently associated with concussion (adjusted odds ratios=1.181, 0.916, and 1.043, respectively). CONCLUSIONS: Relatively simple quantitative measurements of dual-task gait and reaction time may be useful and portable clinical tests in the multifaceted assessment of concussion.

The Association between Dual-Task Gait after Concussion and Prolonged Symptom Duration.

Quantitative gait measurements can identify persistent postconcussion impairments. However, their prognostic utility after injury to identify the likelihood of prolonged concussion symptoms remains unknown. Our objective was to examine if dual-task gait performance measures are independently associated with persistent (> 28 days) concussion symptoms among a sample of athletes. Sixty individuals diagnosed with a sport-related concussion were assessed within 10 days of their injury. Each participant completed a postconcussion symptom scale, an injury history questionnaire, and a single/dual-task gait examination. They were followed until they no longer reported symptoms, and the duration of time required for symptom resolution was calculated. A binary multivariable logistic regression model determined the independent association between dual-task gait and symptom duration (≤ 28 days vs. >28 days) while controlling for the effect of gender, age, symptom severity, injury-to-examination time, and history of concussion. Seventeen (28%) participants reported a symptom duration >28 days. The dual-task cost for average gait speed (-25.9 ± 9.5% vs. -19.8 ± 8.9%; p = 0.027) and cadence (-18.0 ± 2.9% vs. -12.0 ± 7.7%; p = 0.029) was significantly greater among participants who experienced symptoms for >28 days. After adjusting for potential confounding variables, greater dual-task average gait speed costs were independently associated with prolonged symptom duration (aOR = 0.908; 95% CI = 0.835-0.987). Examinations of dual-task gait may provide useful information during multifaceted concussion examinations. Quantitative assessments that simultaneously test multiple domains, such as dual tasks, may be clinically valuable after a concussion to identify those more likely to experience symptoms for >28 days after injury.

Blood Pressure and LV Remodeling Among American-Style Football Players.

OBJECTIVES: This study sought to determine the relationships among American-style football (ASF) participation, acquired left ventricular (LV) hypertrophy, and LV systolic function as assessed using contemporary echocardiographic parameters. BACKGROUND: Participation in ASF has been associated with development of hypertension and LV hypertrophy. To what degree these processes impact LV function is unknown. METHODS: This was a prospective, longitudinal cohort study evaluating National Collegiate Athletic Association Division I football athletes stratified by field position (linemen: n = 30; vs. nonlinemen, n = 57) before and after a single competitive season, using transthoracic echocardiography. LV systolic function was measured using complementary parameters of global longitudinal strain (GLS) (using 2-dimensional speckle-tracking) and ejection fraction (EF) (2-dimensional biplane). RESULTS: ASF participation was associated with field position-specific increases in systolic blood pressure (SBP) (a Δ SBP of 10 ± 8 mm Hg in linemen vs. a Δ SBP of 3 ± 7 mm Hg in nonlinemen; p < 0.001) and an overall increase in incident LV hypertrophy (pre-season = 8% vs. post-season = 25%, p < 0.05). Linemen who developed LV hypertrophy had concentric geometry (9 of 11 [82%]) with decreased GLS (Δ = -1.1%; p < 0.001), whereas nonlinemen demonstrated eccentric LV hypertrophy (8 of 10 [80%]) with increased GLS (Δ = +1.4%; p < 0.001). In contrast, LV ejection fraction in the total cohort, stratified by field position, was not significantly affected by ASF participation. Among the total cohort, lineman field position, post-season weight, SBP, average LV wall thickness, and relative wall thickness were all independent predictors of post-season GLS. CONCLUSIONS: ASF participation at a lineman field position may lead to a form of sport-related myocardial remodeling that is pathologic rather than adaptive. Future study will be required to determine if targeted efforts to control blood pressure, minimize weight gain, and to include an element of aerobic conditioning in this subset of athletes may attenuate this process and translate into tangible downstream health benefits.

Exercise-Induced Left Ventricular Remodeling Among Competitive Athletes: A Phasic Phenomenon.

BACKGROUND: Contemporary understanding of exercise-induced cardiac remodeling is based on cross-sectional data and relatively short duration longitudinal studies. Temporal progression of exercise-induced cardiac remodeling remains incompletely understood. METHODS AND RESULTS: A longitudinal repeated-measures study design using 2-dimensional and speckle-tracking echocardiography was used to examine acute augmentation phase (AAP; 90 days) and more extended chronic maintenance phase (39 months) left ventricular (LV) structural and functional adaptations to endurance exercise training among competitive male rowers (n=12; age 18.6±0.5 years). LV mass was within normal limits at baseline (93±9 g/m(2)), increased after AAP (105±7 g/m(2); P=0.001), and further increased after chronic maintenance phase (113±10 g/m(2); P<0.001 for comparison to post-AAP). AAP LV hypertrophy was driven by LV dilation (ΔLV end-diastolic volume, 9±3 mL/m(2); P=0.004) with stable LV wall thickness (ΔLV wall thickness, 0.3±0.1 mm; P=0.63). In contrast, chronic maintenance phase LV hypertrophy was attributable to LV wall thickening (Δ LV wall thickness, 1.1±0.4 mm; P=0.004) with stable LV chamber volumes (ΔLV end-diastolic volume, 1±1 mL/m(2); P=0.48). Early diastolic peak tissue velocity increased during AAP (-11.7±1.9 versus -13.6±1.3 cm/s; P<0.001) and remained similarly increased after chronic maintenance phase. CONCLUSIONS: In a small sample of competitive endurance athletes, exercise-induced cardiac remodeling follows a phasic response with increases in LV chamber size, early diastolic function, and systolic twist in an acute augmentation phase of exercise training. This is followed by a chronic phase of adaptation characterized by increasing wall thickness and regression in LV twist. Training duration is a determinant of exercise-induced cardiac remodeling and has implications for the assessment of myocardial structure and function in athletes.

Endurance Exercise-Induced Cardiac Remodeling: Not All Sports Are Created Equal.

BACKGROUND: The term endurance sport (ES) is broadly used to characterize any exercise that requires maintenance of high cardiac output over extended time. However, the relative amount of isotonic (volume) versus isometric (pressure) cardiac stress varies across ES disciplines. To what degree ES-mediated cardiac remodeling varies, as a function of superimposed isometric stress, is uncertain. The aim of this study was to compare the cardiac remodeling characteristics associated with two common yet physiologically distinct forms of ES. METHODS: Healthy competitive male long-distance runners (high isotonic, low isometric stress; n = 40) and rowers (high isotonic, high isometric stress; n = 40) were comparatively studied after 3 months of sport-specific exercise training with conventional and speckle-tracking two-dimensional echocardiography. RESULTS: Rowers demonstrated dilated left ventricular (LV) volumes and elevated LV mass (i.e., eccentric LV hypertrophy), whereas runners demonstrated normal LV mass (runners, 88 ± 11 g/m(2); rowers, 108 ± 13 g/m(2); P < .001) despite comparatively larger LV volumes (runners, 101 ± 10 mL/m(2); rowers, 89 ± 13 mL/m(2); P < .001) consistent with eccentric LV remodeling. Increasing LV mass was associated with increased reliance on early diastolic filling (LV mass vs E'/A' ratio, R = 0.47, P < .001) indicating "mass-dependent" diastolic function. Right ventricular dilation of similar magnitude and LV systolic function, as assessed by numerous complementary indices, were similar in both groups. CONCLUSIONS: Cardiac adaptations differ significantly as a function of ES discipline. Further work is required to determine the mechanisms for this differential adaptation, to develop definitive ES discipline-specific normative values, and to evaluate the optimal therapeutic use of specific ES disciplines among patients with common cardiovascular diseases.

HDL surface lipids mediate CETP binding as revealed by electron microscopy and molecular dynamics simulation.

Cholesteryl ester transfer protein (CETP) mediates the transfer of cholesterol esters (CE) from atheroprotective high-density lipoproteins (HDL) to atherogenic low-density lipoproteins (LDL). CETP inhibition has been regarded as a promising strategy for increasing HDL levels and subsequently reducing the risk of cardiovascular diseases (CVD). Although the crystal structure of CETP is known, little is known regarding how CETP binds to HDL. Here, we investigated how various HDL-like particles interact with CETP by electron microscopy and molecular dynamics simulations. Results showed that CETP binds to HDL via hydrophobic interactions rather than protein-protein interactions. The HDL surface lipid curvature generates a hydrophobic environment, leading to CETP hydrophobic distal end interaction. This interaction is independent of other HDL components, such as apolipoproteins, cholesteryl esters and triglycerides. Thus, disrupting these hydrophobic interactions could be a new therapeutic strategy for attenuating the interaction of CETP with HDL.

ECG findings in competitive rowers: normative data and the prevalence of abnormalities using contemporary screening recommendations.

BACKGROUND/AIM: The international governing body for competitive rowing recently mandated the inclusion of 12-lead ECG during preparticipation screening. We therefore sought to describe normative ECG characteristics and to examine the prevalence of abnormal ECG findings as defined by contemporary athlete ECG interpretation criteria among competitive rowers. METHODS: Competitive rowers (n=330, 56% male) underwent standard 12-lead ECG at the time of collegiate preparticipation screening. ECGs were analysed quantitatively to develop a sport-specific normative database and then for the presence of abnormalities in accordance with the 2010 European Society of Cardiology (ESC) recommendations and 2013 'Seattle Criteria.' RESULTS: 94% of rowers had one or more training-related ECG patterns including sinus bradycardia (51%), sinus arrhythmia (55%), and incomplete right bundle branch block (42%). Males were more likely than females to have isolated voltage criteria for left ventricular hypertrophy (LVH) (51% vs 8%, p<0.001) and early repolarisation pattern (76% vs 23%, p<0.001). Application of the 2010 ESC criteria, compared to the Seattle criteria, resulted in the classification of a significantly greater number of abnormal ECGs (47% vs 4%; p<0.001). The detection of true pathology, accomplished by both interpretation criteria, was confined to a single case of ventricular pre-excitation. CONCLUSIONS: Training-related ECG patterns with several gender-based differences are common among competitive rowers. The diagnostic accuracy and down-stream clinical implications of ECG-inclusive preparticipation screening among rowers will be dictated by the choice and future refinement of ECG interpretation criteria.

Impact of American-style football participation on vascular function.

Although hypertension is common in American-style football (ASF) players, the presence of concomitant vascular dysfunction has not been previously characterized. We sought to examine the impact of ASF participation on arterial stiffness and to compare metrics of arterial function between collegiate ASF participants and nonathletic collegiate controls. Newly matriculated collegiate athletes were studied longitudinally during a single season of ASF participation and were then compared with healthy undergraduate controls. Arterial stiffness was characterized using applanation tonometry (SphygmoCor). ASF participants (n = 32, 18.4 ± 0.5 years) were evenly comprised of Caucasians (n = 14, 44%) and African-Americans (n = 18, 56%). A single season of ASF participation led to an increase in central aortic pulse pressure (27 ± 4 vs 34 ± 8 mm Hg, p <0.001). Relative to controls (n = 47), pulse wave velocity was increased in ASF participants (5.6 ± 0.7 vs 6.2 ± 0.9 m/s, p = 0.002). After adjusting for height, weight, body mass index, systolic blood pressure, and diastolic blood pressure, ASF participation was independently predictive of increased pulse wave velocity (ß = 0.33, p = 0.04). In conclusion, ASF participation leads to changes in central hemodynamics and increased arterial stiffness.