Myocarditis in Athletes: Risk Factors and Relationship with Strenuous Exercise.

Amidst the SARS-CoV-2 pandemic, myocarditis in athletes has demanded increased attention primarily because of the risk of sudden cardiac death. While most athletes who experience myocardial inflammation recover, extensive measures for screening and diagnosis are taken because of the possibility of cardiac necrosis, fibrosis, and remodeling. Several risk factors have been identified that may contribute to the development of this inflammatory response, predominantly a history of viral or bacterial upper-respiratory infections. Recent research suggests new risks specific to athletes remain in question, such as the intensity and longevity of sustained exercise, vaccination status, and genetic and epidemiologic factors. Electrocardiography, echocardiography, and cardiac magnetic resonance imaging are commonly utilized for the diagnosis of myocarditis; however, reference standards are lacking because of the variety of clinical presentations. In this article, we discuss the epidemiology, pathophysiology, and presentation of myocarditis in athletes. We then review the available literature to provide a deeper insight into the diagnostic testing methods available, with the aim of outlining the efficacy and prognostic value. Next, we discuss an algorithmic approach to patient care and treatment based upon hemodynamic stability, symptoms, and findings on testing. Finally, this article reviews the current return to play guidelines and the rationale for revisions to return-to-play protocols.

Stimulant Therapy Utilization for Neurocognitive Deficits in Mild Traumatic Brain Injury.

CONTEXT: There are 3.8 million mild traumatic brain injuries (mTBIs) that occur each year in the United States. Many are left with prolonged life-altering neurocognitive deficits, including difficulties in attention, concentration, mental fatigue, and distractibility. With extensive data on the safety and efficacy of stimulant medications in treating attention deficit, concentration difficulties and distractibility seen with attention deficit disorder, it is not surprising that interest continues regarding the application of stimulant medications for the persistent neurocognitive deficits in some mTBIs. EVIDENCE ACQUISITION: Studies were extracted from PubMed based on the topics of neurocognitive impairment, mTBI, stimulant use in mTBI, stimulants, and the association between attention deficit/hyperactivity disorder and mTBI. The search criteria included a date range of 1999 to 2020 in the English language. STUDY DESIGN: Literature review. LEVEL OF EVIDENCE: Level 4. RESULTS: Currently, there is very limited literature, and no guidelines for evaluating the use of stimulant medication for the treatment of prolonged neurocognitive impairments due to mTBI. However, a limited number of studies have demonstrated efficacy and safety of stimulants in the treatment of neurocognitive sequelae of mTBI in the adult, pediatric, military, and athletic populations. CONCLUSION: There is limited evidence to suggest stimulant medication may be beneficial in patients with mTBI with persistent neurocognitive symtpoms. The decision to utilize stimulant medication for mTBI patients remains physician and patient preference dependent. Given the limited encouraging data currently available, physicians may consider stimulant medication in appropriate patients to facilitate the recovery of prolonged neurocognitive deficits, while remaining cognizant of potential adverse effects.

Predicting Concussion Recovery with PHQ-9 and GAD-7.

OBJECTIVE: To determine whether scores obtained from Patient Health Questionnaire-9 (PHQ-9) or the General Anxiety Disorder-7 (GAD-7) instruments administered following a concussion can be used to predict recovery time. METHOD: Retrospective cohort study in a university-based specialty concussion center of 502 concussed participants. Participants completed a PHQ-9 and GAD-7 during their initial visit and subsequent visits during the recovery period (ie, at 14, 28, 56, and 84 days). RESULTS: The median recovery time from a concussion was 21 days from the initial clinical evaluation; however, individuals with a PHQ-9 score ≤ 6 (n = 262) had a median recovery time of 17 (95% confidence interval [CI] 15-19) days, whereas those with PHQ-9 scores >6 (n = 240) had a median recovery time of 33 (95% CI 28-37) days and a hazard ratio of 0.525 (95% CI 0.438-0.629, P < 0.0001). For individuals with a GAD-7 score ≤ 4 (n = 259), the median recovery was 19 (95% CI 17-21), days whereas for those with a GAD-7 score > 4 (n = 243), the median recovery was 32 (95% CI 28-36) days with a hazard ratio of 0.554 (95% CI 0.462-0.664, P < 0.00). CONCLUSIONS: Scores obtained from PHQ-9 and GAD-7 screening tools appear to be predictive of an individual's recovery and may help identify those subjects who may benefit from early psychological interventions.

Fetal Hemoglobin Modulators May Be Associated With Symptomology of Football Players with Sickle Cell Trait.

OBJECTIVES: This study investigates whether genetic modifiers previously shown to influence adult fetal hemoglobin (HbF) levels and glucose-6-phosphate dehydrogenase deficiency were associated with variable symptomology in a small sample of collegiate football players with sickle cell trait. METHODS: Survey data on self-assessed symptoms and genotype data from five single nucleotide polymorphisms (SNPs) related to HbF production and two SNPs that cause glucose-6-phosphate dehydrogenase deficiency were collected from current and former college football players. RESULTS: In this sample, SNPs found within the ß-globin gene cluster were found to be associated with a previous diagnosis of exertional sickling and experience of extreme heat during and after training. rs10189857 in the BCL11A gene was associated with body mass index and weight and with experiencing extreme thirst during and after training. No significant correlations were found between the other SNPs and symptoms within this sample. CONCLUSIONS: These findings show that genetic variation known to affect sickle cell disease symptomology may partly explain why some football players with sickle cell trait experience adverse clinical outcomes during periods of extreme physical exertion and others do not.

Sternal Injuries in Sport: A Review of the Literature.

Sternal fractures were first described in published literature in the 19th century as a complication of traumatic injury. Though sternal fracture and other sternal injuries have been described in trauma literature, there remains a paucity of literature with regards to sternal injury in sport. Sternal injury may include disruption at the body, manubrium and xiphoid process, or at associated sternoclavicular, manubriosternal, and xiphisternal joints. In the athlete it is imperative to evaluate sternal injury with consideration of potentially devastating cardiothoracic complications. Return-to-play protocols should be individualized, taking into account subjective history, objective physical examination and diagnostics, current clinical guidelines, and individual sport-specific considerations. The literature regarding sternal injury is reviewed, with emphasis on sport-specific pathology, management, and return to play.

Examining the Influence of Exercise Intensity and Hydration on Gastrointestinal Temperature in Collegiate Football Players.

DeMartini-Nolan, JK, Martschinske, JL, Casa, DJ, Lopez, RM, Stearns, RL, Ganio, MS, and Coris, E. Examining the influence of exercise intensity and hydration on gastrointestinal temperature in collegiate football players. J Strength Cond Res 32(10): 2888-2896, 2018-Debate exists regarding the influence of intensity and hydration on body temperature during American football. The purpose of this study was to observe body core temperature responses with changes in intensity and hydration. Twenty-nine male football players (age = 21 ± 1 year, height = 187 ± 9 cm, mass = 110.1 ± 23.5 kg, body mass index [BMI] = 31.3 ± 5.0, and body surface area [BSA] = 2.34 ± 0.27 m) participated in 8 days of practice in a warm environment (wet bulb globe temperature: 29.6 ± 1.6° C). Participants were identified as starters (S; n = 12) or nonstarters (n = 17) and linemen (L; n = 14) or nonlinemen (NL; n = 15). Variables of interest included core body temperature (T), hydration status, and physical performance characteristics as measured by a global positioning system. Intensity measures of average heart rate (138 ± 9 bpm), low-velocity movement (4.2 ± 1.7%), high-velocity movement (0.6 ± 0.6%), and average velocity (0.36 ± 0.10 m·s) accounted for 42% of the variability observed in T (38.32 ± 0.34° C, r = 0.65, p = 0.01). Hydration measures (percent body mass loss = -1.56 ± 0.80%, urine specific gravity [Usg] = 1.025 ± 0.006, and urine color [Ucol] = 6 ± 1) did not add to the prediction of T (p = 0.83). Metrics of exercise intensity accounted for 39% of the variability observed in maximum T (38.83 ± 0.42° C, r = 0.62, p = 0.02). Hydration measures did not add to this prediction (p = 0.40). Low-velocity movement, high-velocity movement, average velocity, BMI, and BSA were significantly different (p = 0.002, p < 0.001, p = 0.02, p < 0.001, p < 0.001, respectively) between L vs. NL. Heart rate and T were not different between L and NL (p > 0.05). Exercise intensity primarily accounted for the rise in core body temperature. Although L spent less time at higher velocities, T was similar to NL, suggesting that differences in BMI and BSA added to thermoregulatory strain.

Diagnostic Evaluation of Nontraumatic Chest Pain in Athletes.

This article is a clinically relevant review of the existing medical literature relating to the assessment and diagnostic evaluation for athletes complaining of nontraumatic chest pain. The literature was searched using the following databases for the years 1975 forward: Cochrane Database of Systematic Reviews; CINAHL; PubMed (MEDLINE); and SportDiscus. The general search used the keywords chest pain and athletes. The search was revised to include subject headings and subheadings, including chest pain and prevalence and athletes. Cross-referencing published articles from the databases searched discovered additional articles. No dissertations, theses, or meeting proceedings were reviewed. The authors discuss the scope of this complex problem and the diagnostic dilemma chest pain in athletes can provide. Next, the authors delve into the vast differential and attempt to simplify this process for the sports medicine physician by dividing potential etiologies into cardiac and noncardiac conditions. Life-threatening causes of chest pain in athletes may be cardiac or noncardiac in origin, which highlights the need for the sports medicine physician to consider pathology in multiple organ systems simultaneously. This article emphasizes the importance of ruling out immediately life threatening diagnoses, while acknowledging the most common causes of noncardiac chest pain in young athletes are benign. The authors propose a practical algorithm the sports medicine physician can use as a guide for the assessment and diagnostic work-up of the athlete with chest pain designed to help the physician arrive at the correct diagnosis in a clinically efficient and cost-effective manner.

Left Ventricular Non-Compaction in Athletes: To Play or Not to Play.

Isolated left ventricular non-compaction (LVNC) has usually been viewed as a rare cardiomyopathy in athletes. However, with advances in diagnostic imaging techniques and increased use of pre-participation screening electrocardiograms (ECGs), apparent LVNC is being recognized in an increasing number of athletes. Given the lack of a true gold standard for diagnosis, significant debate continues regarding optimal diagnostic criteria. There are increasing data to support the possibility of over-diagnosing this cardiomyopathy in an athletic population due to the physiologic adaptation to the extreme preload and afterload characteristic of intense athletic participation. This appears to be particularly true in African-American or African-Caribbean athletes. The most common presenting symptom in the athlete with true LVNC is exertional syncope. Evaluation of the at-risk athlete will typically include a complete history, with attention to cardiac symptoms, family history of premature cardiovascular disease or sudden cardiac death (SCD), physical examination, 12-lead ECG, two-dimensional echocardiography, and, in some cases, cardiac magnetic resonance imaging with gadolinium contrast. In addition, stress echocardiography, 24- to 48-h Holter monitoring, or 30-day event monitoring for arrhythmias may be necessary to fully evaluate the athlete's risk. Adverse outcomes with LVNC include ventricular dysfunction, arrhythmias, syncope, SCD, and thromboembolism. Asymptomatic athletes with hypertrabeculation of the left ventricle but normal ventricular function likely do not require restrictions on activity. Symptomatic individuals who meet criteria for LVNC, especially those with abnormal ventricular function and exercise-induced symptoms or arrhythmias, should be prohibited from participating in vigorous sports activities.

Postconcussive Syndrome Following Sports-related Concussion: A Treatment Overview for Primary Care Physicians.

Postconcussive syndrome is an increasingly recognized outcome of sports-related concussion (SRC), characterized by a constellation of poorly defined symptoms. Treatment of PCS is significantly different from that of SRC alone. Primary care physicians often are the first to evaluate these patients, but some are unfamiliar with the available therapeutic approaches. This review provides an overview of the pathophysiology of SRC and descriptions of both pharmacologic and nonpharmacologic treatment options to allow primary care physicians to provide evidence-based care to patients experiencing postconcussive syndrome.

Maximum heat loss potential is lower in football linemen during an NCAA summer training camp because of lower self-generated air flow.

The purpose of this study was to compare the maximum potential for heat loss of football linemen (L) and non-linemen (NL) during a National Collegiate Athletic Association (NCAA) summer training camp. It was hypothesized that heat loss potential in L would be lower than NL because of differences in self-generated air flow during position-specific activities. Fourteen NCAA division 1 football players {7 L (mass: 126 ± 6 kg; body surface area [BSA]: 2.51 ± 0.19 m(2)) and 7 NL (mass: 88 ± 13 kg; BSA: 2.09 ± 0.18 m(2))} participated over 6 days in southern Florida (Tdb: 31.2 ± 1.6 °C, T(wb): 27.0 ± 0.7 °C, Tr: 38.4 ± 2.8° C). Simultaneous on-field measurements of self-generated air velocities (v(self)) and mean skin temperatures (Tsk) were performed throughout practice, which included 4 drill categories (special teams, wind sprints, individual drills, and team drills). The resultant net potential for heat loss through convection, radiation, and evaporation (H(total)) was calculated. Values for Tsk were similar between L and NL for all drills (L: 35.4 ± 0.8 °C; NL: 35.4 ± 0.4 °C; p = 0.92). However, v(self) was greater in NL during wind sprints, individual drills, and team drills (p ≤ 0.05). Consequently H(total) was significantly greater in NL for all drills except special teams (p ≤ 0.05). The mean estimated rate of oxygen consumption needed to exceed H(total) was 8.6 ± 1.3 ml · kg(-1) · min(-1) (2.5 ± 0.4 METs) for NL but only 5.6 ± 1.4 ml · kg(-1) · min(-1) (1.6 ± 0.4 METs) for L. A lower heat loss potential occurs in L because of the more static nature of their position-related activities and not because of differences in Tsk. The practical relevance of these findings is that potential interventions that increase convective and evaporative heat loss (i.e., mechanical fans) should specifically target L, particularly while they are participating in static on-field drills and during rest intervals.

Cutaneous myiasis masquerading as methicillin-resistant Staphylococcus aureus.

Numerous factors place athletes at increased risk for cutaneous infections, and as such, they are a common complaint in athletic training rooms. Methicillin-resistant Staphylococcus aureus (MRSA) is an increasingly common etiology, and given its severe sequelae, a high index of suspicion in this population is justified. We present 2 cases of college athletes who presented to the athletic training room with findings suspicious for MRSA infection. However, after further investigation, the true diagnosis of myiasis was reached. These cases highlight the importance of asking athletes about recent travel and considering a broad differential diagnosis when evaluating furuncular lesions.

Preparticipation cardiovascular screening among National Collegiate Athletic Association Division I institutions.

BACKGROUND: Sudden cardiac arrest is the leading cause of death in competitive athletes during sport, and screening strategies for the prevention of sudden cardiac death are debated. The purpose of this study was to assess the incorporation of routine non-invasive cardiovascular screening (NICS), such as ECG or echocardiography, in Division I collegiate preparticipation examinations. METHODS: Cross-sectional survey of current screening practices sent to the head athletic trainer of all National Collegiate Athletic Association (NCAA) Division I football programmes listed in the National Athletic Trainers' Association directory. RESULTS: Seventy-four of 116 (64%) programmes responded. Thirty-five of 74 (47%) of responding schools have incorporated routine NICS testing. ECG is the primary modality for NICS in 31 (42%) of schools, and 17 (49%) also utilise echocardiography. Sixty-four per cent of the programmes that do NICS routinely screen their athletes only once as incoming freshmen. Of institutions that do not conduct NICS, American Heart Association guidelines against routine NICS and cost were the most common reasons reported. CONCLUSIONS: While substantial debate exists regarding protocols for cardiovascular screening in athletes, nearly half of NCAA Division I football programmes in this study already incorporate NICS into their preparticipation screening programme. Additional research is needed to understand the impact of NICS in collegiate programmes.

Sweating is greater in NCAA football linemen independently of heat production.

PURPOSE: The study's purpose was to investigate whether differences in local sweat rates on the upper body between American football linemen (L) and backs (B) exist independently of differences in metabolic heat production. METHODS: Twelve NCAA Division I American football players (6 linemen (mass = 141.6 ± 6.5 kg, body surface area (BSA) = 2.67 ± 0.08 m2) and 6 backs (mass = 88.1 ± 13.4 kg, BSA = 2.11 ± 0.19 m2)) cycled at a fixed metabolic heat production per unit BSA of 350 W·m(-2) for 60 min in a climatic chamber (t(db) [dry bulb temperature] = 32.4°C ± 1.0°C, t(wb) [wet bulb temperature] = 26.3°C ± 0.6°C, v [air velocity] = 0.9 ± 0.1 m·s(-1)). Local sweat rates on the head, arm, shoulder, lower back, and chest were measured after 10, 30, and 50 min of exercise. Core temperature, mean skin temperature, and HR were measured throughout exercise. RESULTS: Because metabolic heat production per unit surface area was fixed between participants, the rate of evaporation required for heat balance was similar (L = 261 ± 35 W·m(-2), B = 294 ± 30 W·m(-2), P = 0.11). However, local sweat rates on the head, arm, shoulder, and chest were all significantly greater (P < 0.05) in linemen at all time points, and end-exercise core temperature was significantly greater (P = 0.033) in linemen (38.5°C ± 0.4°C) relative to backs (38.0°C ± 0.2°C) despite a ∼25% lower heat production per unit mass. The change in mean skin temperature from rest was greater in linemen (P < 0.001) after 15, 30, 45, and 60 min, and HR was greater in linemen for the last 30 min of exercise. CONCLUSIONS: Football linemen sweat significantly more on the torso and head than football backs independently of any differences in metabolic heat production per unit BSA and therefore the evaporative requirements for heat balance. Despite greater sweating, linemen demonstrated significantly greater elevations in core temperature suggesting that sweating efficiency (i.e., the proportion of sweat that evaporates) was much lower in linemen.

Physical demands of National Collegiate Athletic Association Division I football players during preseason training in the heat.

The purpose of this study was to evaluate physical demands of football players during preseason practices in the heat. Furthermore, we sought to compare how physical demands differ between positions and playing status. Male National Collegiate Athletic Association Division 1 football players (n = 49) participated in 9 practice sessions (142 ± 16 minutes per session; wet bulb globe temperature (WBGT) 28.75 ± 2.11°C) over 8 days. Heart rate (HR) and global positioning system data were recorded throughout the entirety of each practice to determine the distance covered (DC), velocity (V), maximal HR (HRmax), and average HR (HRavg). The subjects were divided into 2 groups: linemen (L) (N = 25; age: 22 ± 1 years, weight: 126 ± 16 kg, height: 190 ± 4 cm,) vs. nonlinemen (NL) (N = 24; age: 21 ± 1 years, weight: 91 ± 11 kg, height: 183 ± 8 cm) and starters (S) (N = 17; age: 21 ± 1 years, weight: 118 ± 21 kg, height: 190 ± 7 cm) vs. nonstarters (NS) (N = 32; age: 20 ± 1 years, weight: 105 ± 22 kg, height: 185 ± 7 cm) for statistical analysis. The DC (3,532 ± 943 vs. 2,573 ± 489 m; p = 0.001) and HRmax (201 ± 9 vs. 194 ± 11 b·min(-1); p = 0.025) were significantly greater in NL compared with that in L. In addition, NL spent more time (p < 0.0001) and covered more distance (p = 0.002) at higher velocities than L did. Differences between S vs. NS were observed (p = 0.008, p = 0.031), with S obtaining higher velocities than NS did. Given the demands of their playing positions, NL were required to cover more distance at higher velocities, resulting in a greater HRmax than that of L. Therefore, it appears that L engage in more isometric work than NL do. In addition, the players exposed to similar practice demands provide similar work output during preseason practice sessions regardless of their playing status.

Office-based ultrasound in sports medicine practice.

Increasing knowledge, interest, and visibility in the field of sports medicine has equipped clinicians in the field with a novel array of diagnostic and therapeutic options but has also provided a higher level of complexity in patient care. True understanding of the vast spectrum of radiographic technology available to the sports clinician has become more critical than ever. Advances particularly in the areas of magnetic resonance imaging, diagnostic office ultrasound, and 3-dimensional reconstruction computed tomography, as well as nuclear medicine, offer the clinician a myriad of diagnostic options in patient evaluation. As these advances accumulate, the challenge to optimize care, contain cost, and interpret the extensive data generated becomes even more difficult to manage. Improving technology, education, and application of office ultrasound offers an interesting new tool for the bedside evaluation in real time of dynamic motion and pathology of sports-related injuries. As studies continue to validate ultrasound's effectiveness in diagnosing injuries to the upper and lower extremities compared with more costly magnetic resonance imaging and more invasive exploratory surgery, its promise as a cost-effective diagnostic tool is growing. A particularly promising development in the care of sports injuries is the expansion of injection therapies, and in-office ultrasound provides assurance that prolotherapy, platelet-rich plasma, dry needling, corticosteroid, and viscosupplementation are delivered accurately and safely. Communication with patients continues to increase in complexity because a greater understanding of the presence of radiographic abnormalities irrelevant to the current complaint is gained. All the accumulated data must then be interpreted and communicated to the patient with a firm understanding of not only the patient history and physical examination but also the availability, indications, contraindications, sensitivity, specificity, and even the cost implications of the spectrum of diagnostic options.

Gastrointestinal temperature trends in football linemen during physical exertion under heat stress.

CONTEXT: Exertional heat stroke is the third leading cause of death in US athletes. Elevations in core temperature in the digestive tract (TGI) have correlated with core temperature and are possible indicators of those at increased risk of heat stroke. OBJECTIVE: The primary objective was to compare a.m. vs. p.m. TGI variation in collegiate football linemen during intense "two-a-day" preseason practice. A secondary objective was to compare longitudinal TGI in offensive and defensive linemen. DESIGN: Cross-sectional observational study. SETTING: Division I Intercollegiate Athletics Football Program. INTERVENTIONS: TGI was monitored during consecutive preseason sessions. MAIN OUTCOME MEASUREMENTS: TGI, heat illness, weight changes, environmental stress, and subjective symptoms. RESULTS: Mean TGI were 37.8°C and 38.3°C during a.m. and p.m. practices, respectively. The a.m. practices revealed higher TGI gain (1.8°C) compared to p.m. (1.4°C). The p.m. practices had higher maximum TGI than a.m. practices (39.1°C versus 38.8, P=0.0001). Mean time to maximum temperature (Tmax) was 1 hr and 30 min for a.m. and 1 hr and 22 min for p.m. practices. Offensive linemen trended toward higher mean TGI than defensive players (38.0°C vs. 36.7°C, P = 0.069). The rate of rise in TGI was significantly greater in a.m. practices. A decrease in rate of TGI rise was seen from the first to last a.m. practices of the week (P = 0.004). CONCLUSION: Significant TGI elevations in asymptomatic athletes are common in extreme heat during football practice. Intense a.m. practices in full gear result in higher net temperature gain and rate of temperature gain than p.m. practices. Offensive linemen trended toward higher TGI than defensive linemen. As players acclimatized, a decrease in the rate of TGI increase was appreciable, particularly in a.m. practices. Appreciating cumulative heat stress and variations in heat stress related to scheduling of practice is critical.

Imaging in sports medicine: an overview.

Increasing sports participation, and the inevitable sports injury, is a significant contributor to total healthcare expenditure in the United States. With sports-related injury ever increasing, and technology rapidly expanding in the areas of diagnosis and treatment of musculoskeletal trauma, a continual revisiting of the latest in technology is critical for the sports physician. Advances particularly in the areas of magnetic resonance imaging, diagnostic office ultrasound, and 3-dimensional reconstruction computed tomography, offer the clinician a myriad of diagnostic options in patient evaluation. Care must be exercised, however, as one pursues additional radiographic data in the patient care arena. The information must be interpreted with a firm foundation and understanding of not only the patient history and physical examination, but also the availability, indications, contraindications, sensitivity, specificity, and even the cost implications of the great spectrum of diagnostic options.

Return to activity considerations in a football player predisposed to exertional heat illness: a case study.

CONTEXT: Heat illness is the third leading cause of death in athletics and a leading cause of morbidity and mortality in exercising athletes. Once faced with a case of heat related illness, severe or mild, the health care professional is often faced with the question of when to reactivate the athlete for competitive sport. Resuming activity without modifying risk factors could lead to recurrence of heat related illness of similar or greater severity. Also, having had heat illness in and of itself may be a risk factor for future heat related illness. The decision to return the athlete and the process of risk reduction is complex and requires input from all of the components of the team. Involving the entire sports medicine team often allows for the safest, most successful return to play strategy. Care must be taken once the athlete does begin to return to activity to allow for re-acclimatization to exercise in the heat prior to resumption particularly following a long convalescent period after more severe heat related illness.

Heat illness symptom index (HISI): a novel instrument for the assessment of heat illness in athletes.

BACKGROUND: Heatstroke is the third leading cause of death in athletics, and an important cause of morbidity and mortality in exercising athletes. There is no current method, however, for identifying milder forms of heat illness. In this pilot study, we sought to develop and provide initial validation for a Heat Illness Symptom Index scale (HISI) that would facilitate research in the assessment of milder forms of heat illness in athletes. METHODS: The study was designed as a multimodal prospective observational study of Division I football players during twice daily practices in southern Florida. We developed a 13-item scale that assessed symptoms that are suspected to occur during milder forms of heat illness. The resultant scale was assessed for reliability using Cronbach's alpha, and was assessed for construct validity by correlating scale scores with factors that are known to be related to heat illness. HISI scores, as well as data on perceived exertion, player position, and pre and post practice weights were collected from 95 athletes participating in late summer football practices. A total of 557 athlete sessions were analyzed. RESULTS: The mean score on the heat illness symptom scale was 12.1 (SD 13.8) and the median value was 8.0. Cronbach's alpha confirmed suitable internal consistency of the scale when assessed separately for each of the five morning practices (alpha = 0.91, 0.88, 0.82, 0.92, 0.85). There were statistically significant correlations of the scale score with weight loss during practice (P = 0.006), rating of perceived exertion (P = 0.005), player position (P < 0.0001), and ambient heat index (P = 0.02) as hypothesized. CONCLUSIONS: This pilot study provides initial validation for a novel symptom-based tool for use in assessing mild forms of heat illness in an athletic population. Further validation studies of the instrument, and correlating symptom scores with measures of core temperature, are needed and planned.