Eric E. Coris

Heat illness in athletes: the dangerous combination of heat, humidity and exercise.

In 1980, 1700 people died during a prolonged heat wave in a region under-prepared for heat illness prevention. Dramatically underreported, heat-related pathology contributes to significant morbidity as well as occasional mortality in athletic, elderly, paediatric and disabled populations. Among US high school athletes, heat illness is the third leading cause of death.Significant risk factors for heat illness include dehydration, hot and humid climate, obesity, low physical fitness, lack of acclimatisation, previous history of heat stroke, sleep deprivation, medications (especially diuretics or antidepressants), sweat gland dysfunction, and upper respiratory or gastrointestinal illness. Many of these risk factors can be addressed with education and awareness of patients at risk. Dehydration, with fluid loss occasionally as high as 6–10% of bodyweight, appears to be one of the most common risk factors for heat illness in patients exercising in the heat. Core body temperature has been shown to rise an additional 0.15–0.2°C for every 1% of bodyweight lost to dehydration during exercise.Identifying athletes at risk, limiting environmental exposure, and monitoring closely for signs and symptoms are all important components of preventing heat illness. However, monitoring hydration status and early intervention may be the most important factors in preventing severe heat illness.

First Rib Stress Fractures in Throwing Athletes

Stress fracture of the first rib is a rare cause of shoulder pain in throwing athletes. Early recognition and proper management generally lead to successful outcomes and return to play. Typically presenting as gradually progressive, dull aching pain in the posterior shoulder or upper back, such fractures will occasionally appear acutely with sudden onset of pain and disability related to the complete fracture of a fatigued bone. Diagnosis is made by focal point tenderness in the affected first rib, plain radiographs, and often triple-phase bone scans to confirm the acuity of the fracture. Relative rest until symptoms resolve and then a gradual return to throwing are effective for most patients, with longer periods required in those patients who have a complete fracture. This report describes a unique case of an infielder with a first rib stress fracture of the dominant arm that was evaluated as a complete fracture of a fatigued bone. Our case illustrates the utility of clinical management in first rib stress fractures. A trial of return to throwing at 6 weeks was unsuccessful because of the return of pain with both throwing and batting; therefore, a prolonged convalescence was required. Radiographic follow-up also clearly reveals the delayed healing process of more severe first rib fractures. As with the few other patients with these lesions described in the literature, our patient eventually healed completely and returned to competitive baseball at the collegiate, and eventually the professional, level without incident.

Sudden cardiac death in division I collegiate athletics: analysis of automated external defibrillator utilization in National Collegiate Athletic Association division I athletic programs.

Objective:To determine current outcomes of automated external defibrillator (AED) interventions in sports medicine programs in National Collegiate Athletic Association (NCAA) division I athletics. Design:Qualitative scripted telephone interview with all positive responders to prior NCAA division I-wide study on AED utilization and implementation. Setting:NCAA division I sports medicine programs. Head athletic trainers were the main data source. Participants:All positive responders to a previously published study on AED implementation in the NCAA division I sports medicine community. Positive responders were those that indicated that they had used their departmental AEDs in a sudden cardiac death (SCD) scenario. Main Outcome Measurements:Survival to hospital discharge was the main outcome sought. When available, additional outcomes were time to defibrillation, time to notification of athletic training staff, EMS response time, location of event, and sudden cardiac victim type (i.e., student, coach, fan). Results:Sixteen departments that previously reported having had an SCD event at their institution responded to this follow-up telephone survey. Twenty percent of AED uses were attributed to student athletes, with 33% of utilizations for athletic department staff and 47% for fans. Defibrillation was actually administered in 53% of AED unit applications. Time to shock was an average of 3.4 minutes, with average EMS response time of 8.2 minutes for those events without EMS on site. Reported survival to hospital discharge in this university athletic department setting for SCD was 0% for students, 75% for staff, 57% for fans, and 61% overall. Conclusions:The results of this study demonstrate the need for NCAA division 1 athletic sports medicine programs to examine, and possibly expand, the traditional scope of practice of caring primarily for student athletes to include the larger community of sports participants comprised of athletes, departmental staff, and spectators. Athletic department AED programs were extremely successfully at increasing survival of SCD far above national prehospital standards, mainly in the nonathletic population. Further study is also necessary in the realm of AED placement, maintenance, and training of staff.

Sweating Is Greater in NCAA Football Linemen Independently of Heat Production

PURPOSE The studys 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.

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 Cronbachs 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. Cronbachs 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.

Physical Demands of National Collegiate Athletic Association Division I Football Players During Preseason Training in the Heat

DeMartini, JK, Martschinske, JL, Casa, DJ, Lopez, RM, Ganio, MS, Walz, SM, and Coris, EE. Physical demands of National Collegiate Athletic Association division I football players during preseason training in the heat. J Strength Cond Res 25(11): 2935–2943, 2011—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.

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.

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.

Maximum Heat Loss Potential Is Lower in Football Linemen During an Ncaa Summer Training Camp Because of Lower Self-generated Air Flow

Abstract Deren, TM, Coris, EE, Casa, DJ, DeMartini, JK, Bain, AR, Walz, SM, and Jay, O. Maximum heat loss potential is lower in football linemen during an NCAA summer training camp because of lower self-generated air flow. J Strength Cond Res 28(6): 1656–1663, 2014—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 m2) and 7 NL (mass: 88 ± 13 kg; BSA: 2.09 ± 0.18 m2)} participated over 6 days in southern Florida (Tdb: 31.2 ± 1.6°C, Twb: 27.0 ± 0.7°C, Tr: 38.4 ± 2.8° C). Simultaneous on-field measurements of self-generated air velocities (vself) 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 (Htotal) 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, vself was greater in NL during wind sprints, individual drills, and team drills (p ⩽ 0.05). Consequently Htotal was significantly greater in NL for all drills except special teams (p ⩽ 0.05). The mean estimated rate of oxygen consumption needed to exceed Htotal 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.

Automated External Defibrillators in National Collegiate Athletic Association Division I Athletics

Background Sudden cardiac death is the leading cause of death in athletes. Evidence on current sudden cardiac death prevention through preparticipation history, physicals, and noninvasive cardiovascular diagnostics has demonstrated a low sensitivity for detection of athletes at high risk of sudden cardiac death. Data are lacking on automated external defibrillator programs specifically initiated to respond to rare dysrhythmia in younger, relatively low-risk populations. Methods Surveys were mailed to the head athletic trainers of all National Collegiate Athletic Association Division I athletics programs listed in the National Athletic Trainers’ Association directory. In all, 303 surveys were mailed; 186 departments (61%) responded. Results Seventy-two percent (133) of responding National Collegiate Athletic Association Division I athletics programs have access to automated external defibrillator units; 54% (101) own their units. Proven medical benefit (55%), concern for liability (51%), and affordability (29%) ranked highest in frequency of reasons for automated external defibrillator purchase. Unit cost (odds ratio = 1.01; 95% confidence interval, 1.01-1.0), donated units (odds ratio = 1.92; confidence interval, 3.66-1.01), institution size (odds ratio = .0001; confidence interval, 1.3 E-4 to 2.2E-05), and proven medical benefit of automated external defibrillators (odds ratio = 24; confidence interval, 72-8.1) were the most significant predictors of departmental defibrillator ownership. Emergency medical service response time and sudden cardiac death event history were not significantly predictive of departmental defibrillator ownership. The majority of automated external defibrillator interventions occurred on nonathletes. Conclusions Many athletics medicine programs are obtaining automated external defibrillators without apparent criteria for determination of need. Usage and maintenance policies vary widely among departments with unit ownership or access. Programs need to approach the issue of unit acquisition and implementation with knowledge of the surrounding emergency medical service system, geography of their individual sports medicine facilities, numbers and relative risk of their athletes, and budgetary constraints.