Luke N. Belval

Effectiveness of cold water immersion in the treatment of exertional heat stroke at the Falmouth Road Race.

PURPOSE This study aimed to investigate the effectiveness (speed of cooling and survival rates) of cold water immersion (CWI) in the treatment of patients with exertional heat stroke (EHS). Secondly, this study aimed to compare cooling rates on the basis of gender, age, and initial rectal temperature (Tr). METHODS Eighteen years of finish line medical tent patient records were obtained from the exertional heat illness treatment area at the Falmouth Road Race. Study participants included patients with EHS who were treated with CWI in the medical tent. The number of EHS cases was recorded for each year, and incidence was established on the basis of the number of finishers. Overall cooling rate and differences between initial Tr, age, and sex were evaluated. RESULTS A total of 274 cases of EHS was observed over the 18 yr of collected data. A mean of 15.2 ± 13.0 EHS cases per year was recorded, with an overall incidence of 2.13 ± 1.62 EHS cases per 1000 finishers. The average initial Tr was 41.44°C ± 0.63°C, and the average cooling rate for patients with EHS was 0.22°C·min ± 0.11°C·min. CWI resulted in a 100% survival rate for all patients with EHS. No significant interactions between cooling rate and initial Tr (P = 0.778), sex (P = 0.89), or age (P = 0.70) were observed. CONCLUSIONS CWI was found to effectively treat all cases of EHS observed in this study. CWI provided similar treatment outcomes in all patients, with no significant differences noted on the basis of initial Tr, age, or sex. On the basis of the 100% survival rate from EHS in this large cohort, it is recommended that immediate (on site) CWI be implemented for the treatment of EHS.

Environmental conditions and the occurrence of exertional heat illnesses and exertional heat stroke at the Falmouth Road Race.

CONTEXT The Falmouth Road Race is unique because of the environmental conditions and relatively short distance, which allow runners to maintain a high intensity for the duration of the event. Therefore, the occurrence of exertional heat illnesses (EHIs), especially exertional heat stroke (EHS), is 10 times higher than in other races. OBJECTIVE To summarize the occurrence and relationship of EHI and environmental conditions at the Falmouth Road Race. DESIGN Descriptive epidemiologic study. SETTING An 11.3-km (7-mile) road race in Falmouth, Massachusetts. PATIENTS OR OTHER PARTICIPANTS Runners who sustained an EHI while participating in the Falmouth Road Race. MAIN OUTCOME MEASURE(S) We obtained 18 years of medical records and environmental conditions from the Falmouth Road Race and documented the incidence of EHI, specifically EHS, as related to ambient temperature (Tamb), relative humidity, and heat index (HI). RESULTS Average Tamb, relative humidity, and HI were 23.3 ± 2.5°C, 70 ± 16%, and 24 ± 3.5°C, respectively. Of the 393 total EHI cases observed, EHS accounted for 274 (70%). An average of 15.2 ± 13.0 EHS cases occurred each year; the incidence was 2.13 ± 1.62 cases per 1000 runners. Regression analysis revealed a relationship between the occurrence of both EHI and EHS and Tamb (R(2) = 0.71, P = .001, and R(2) = 0.65, P = .001, respectively) and HI (R(2) = 0.76, P < .001, and R(2) = 0.74, P < .001, respectively). Occurrences of EHS (24.2 ± 15.5 cases versus 9.3 ± 4.3 cases) and EHI (32.3 ± 16.3 versus 13.0 ± 4.9 cases) were higher when Tamb and HI were high compared with when Tamb and HI were low. CONCLUSIONS Because of the environmental conditions and race duration, the Falmouth Road Race provides a unique setting for a high incidence of EHS. A clear relationship exists between environmental stress, especially as measured by Tamb and HI, and the occurrence of EHS or other EHI. Proper prevention and treatment strategies should be used during periods of high environmental temperatures as the likelihood of runners experiencing EHS is exacerbated in these harsh conditions.

Tarp-Assisted Cooling as a Method of Whole-Body Cooling in Hyperthermic Individuals

Study objective: We investigated the efficacy of tarp‐assisted cooling as a body cooling modality. Methods: Participants exercised on a motorized treadmill in hot conditions (ambient temperature 39.5°C [103.1°F], SD 3.1°C [5.58°F]; relative humidity 38.1% [SD 6.7%]) until they reached exercise‐induced hyperthermia. After exercise, participants were cooled with either partial immersion using a tarp‐assisted cooling method (water temperature 9.20°C [48.56°F], SD 2.81°C [5.06°F]) or passive cooling in a climatic chamber. Results: There were no differences in exercise duration (mean difference=0.10 minutes; 95% CI –5.98 to 6.17 minutes or end exercise rectal temperature (mean difference=0.10°C [0.18°F]; 95% CI –0.05°C to 0.25°C [–0.09°F to 0.45°F] between tarp‐assisted cooling (48.47 minutes [SD 8.27 minutes]; rectal temperature 39.73°C [103.51°F], SD 0.27°C [0.49°F]) and passive cooling (48.37 minutes [SD 7.10 minutes]; 39.63°C [103.33°F], SD 0.40°C [0.72°F]). Cooling time to rectal temperature 38.25°C (100.85°F) was significantly faster in tarp‐assisted cooling (10.30 minutes [SD 1.33 minutes]) than passive cooling (42.78 [SD 5.87 minutes]). Cooling rates for tarp‐assisted cooling and passive cooling were 0.17°C/min (0.31°F/min), SD 0.07°C/min (0.13°F/min) and 0.04°C/min (0.07°F/min), SD 0.01°C/min (0.02°F/min), respectively (mean difference=0.13°C [0.23°F]; 95% CI 0.09°C to 0.17°C [0.16°F to 0.31°F]. No sex differences were observed in tarp‐assisted cooling rates (men 0.17°C/min [0.31°F/min], SD 0.07°C/min [0.13°F/min]; women 0.16°C/min [0.29°F/min], SD 0.07°C/min [0.13°F/min]; mean difference=0.02°C/min [0.04°F/min]; 95% CI –0.06°C/min to 0.10°C/min [–0.11°F/min to 0.18°F/min]). Women (0.04°C/min [0.07°F/min], SD 0.01°C/min [0.02°F/min]) had greater cooling rates than men (0.03°C/min [0.05°F/min], SD 0.01°C/min [0.02°F/min]) in passive cooling, with negligible clinical effect (mean difference=0.01°C/min [0.02°F/min]; 95% CI 0.001°C/min to 0.024°C/min [0.002°F/min to 0.04°F/min]). Body mass was moderately negatively correlated with the cooling rate in passive cooling (r=–0.580) but not in tarp‐assisted cooling (r=–0.206). Conclusion: In the absence of a stationary cooling method such as cold‐water immersion, tarp‐assisted cooling can serve as an alternative, field‐expedient method to provide on‐site cooling with a satisfactory cooling rate.

Bike and run pacing on downhill segments predict Ironman triathlon relative success

OBJECTIVES Determine if performance and physiological based pacing characteristics over the varied terrain of a triathlon predicted relative bike, run, and/or overall success. Poor self-regulation of intensity during long distance (Full Iron) triathlon can manifest in adverse discontinuities in performance. DESIGN Observational study of a random sample of Ironman World Championship athletes. High performing and low performing groups were established upon race completion. METHODS Participants wore global positioning system and heart rate enabled watches during the race. Percentage difference from pre-race disclosed goal pace (%off) and mean HR were calculated for nine segments of the bike and 11 segments of the run. Normalized graded running pace (accounting for changes in elevation) was computed via analysis software. Step-wise regression analyses identified segments predictive of relative success and HP and LP were compared at these segments to confirm importance. RESULTS %Off of goal velocity during two downhill segments of the bike (HP: -6.8±3.2%, -14.2±2.6% versus LP: -1.2±4.2%, -5.1±11.5%; p<0.020) and %off from NGP during one downhill segment of the run (HP: 4.8±5.2% versus LP: 33.3±38.7%; p=0.033) significantly predicted relative performance. Also, HP displayed more consistency in mean HR (141±12 to 138±11 bpm) compared to LP (139±17 to 131±16 bpm; p=0.019) over the climb and descent from the turn-around point during the bike component. CONCLUSIONS Athletes who maintained faster relative speeds on downhill segments, and who had smaller changes in HR between consecutive up and downhill segments were more successful relative to their goal times.

Maximizing Athletic Performance in the Heat

ABSTRACT ATHLETES TRAIN AND PERFORM AT OPTIMAL LEVELS IN COOL ENVIRONMENTS; HOWEVER, MANY INDIVIDUALS DO NOT ALTER THEIR TRAINING IN HOT ENVIRONMENTS. THE PURPOSE OF THIS REVIEW IS TO EXPLORE EXISTING RESEARCH RELATED TO ENHANCING PERFORMANCE IN THE HEAT BY MODIFYING THE FOLLOWING PRACTICES: (A) HYDRATION, (B) BODY COOLING, (C) HEAT ACCLIMATIZATION, (D) CLOTHING AND PROTECTIVE EQUIPMENT, (E) NUTRITION AND SUPPLEMENTATION, (F) SLEEP, AND (G) TECHNOLOGY. THIS REVIEW EXPLORES PRACTICAL WAYS ATHLETES CAN CHANGE THEIR EXERCISE HABITS WITH THE GOAL OF INCREASING PERFORMANCE IN HOT ENVIRONMENTS.

Two environmental symptoms questionnaires during 10 days of exercise-heat acclimation.

BACKGROUND The purpose was to: 1) correlate and compare the long Environmental Symptoms Questionnaire (56-ESQ) with markers of heat acclimation; 2) compare the 56-ESQ with a modified version of the ESQ (14-ESQ) over a 10-d exercise heat acclimation protocol; 3) correlate both scales with physiological data; and 4) determine those questions most sensitive to heat acclimation responses to further refine the 14-ESQ. This is reported as a 12-question ESQ (12-ESQ), which was correlated with physiological data. METHODS There were 10 non-trained, non-heat-acclimatized men (age 20 +/- 1 yr; height 184 +/- 8 cm; weight 81.7 +/- 12.2 kg; percent body fat 10.1 +/- 2.9%) who undertook 10 consecutive days of heat acclimation (walking at 5.6 km x h(-1), 5% grade, 90 min duration; 33 degrees C, 30-50% relative humidity). ESQ forms were completed on days 1, 4, 7, and 10 pre- and post-exercise. During exercise, rectal temperature (T(r)), heart rate (HR), and rating of perceived exertion (RPE) were recorded. RESULTS Verification of heat acclimation was based on T(r) and HR, which were significantly lower on day 4 (38.11 +/- 0.25 degrees C, 143 +/- 13 bpm) vs. day 1 (38.46 +/- 0.47 degrees C, 158 +/- 17 bpm) and all subsequent days. All ESQ scales demonstrated a significant effect of time, supporting evidence of heat acclimation. The 56-, 14-, and 12-ESQ post-exercise scores were significantly correlated with HR (r2 = 0.424, 0.353, and 0.430, respectively). The 12-ESQ was correlated with T(r) (r2 = 0.400). DISCUSSION The 12- and 14-ESQ tracked well with the 56-ESQ. All ESQs were able to track physiological variables and symptoms of heat stress. All ESQ forms may be used as an efficient method to indicate environmental heat stress and symptoms.

Comparative Physiology of Thermoregulation

Human thermoregulatory responses represent one point on the spectrum of physiological and behavioral adaptations across the animal kingdom. By examining the wide variety of mechanisms and behaviors that animals employ to cope with changing ambient conditions, we can better understand our own responses to environmental stressors. The examples presented within this chapter highlight both the uniqueness of human thermoregulation and the multifaceted challenges that athletes, laborers, and soldiers endure.

Consensus Statement- Prehospital Care of Exertional Heat Stroke

Abstract Exertional heat stroke (EHS) is one of the most common causes of sudden death in athletes. It also represents a unique medical challenge to the prehospital healthcare provider due to the time sensitive nature of treatment. In cases of EHS, when cooling is delayed, there is a significant increase in organ damage, morbidity, and mortality after 30 minutes, faster than the average EMS transport and ED evaluation window. The purpose of this document is to present a paradigm for prehospital healthcare systems to minimize the risk of morbidity and mortality for EHS patients. With proper planning, EHS can be managed successfully by the prehospital healthcare provider.

Drugs and Supplements

The use of performance enhancing drugs and supplements in sport and physical activity has been around for decades; however, the impact of these drugs and supplements on performance in the heat has been garnering new attention. Although there are some drugs and supplements that can enhance performance in the heat, there are also many that may hinder performance, even potentially increasing the risk of serious illness or death in select circumstances. This chapter will describe and discuss specific drugs and supplements and their effects on performance and safety in the heat.

Top 10 Research Questions Related to Preventing Sudden Death in Sport and Physical Activity

ABSTRACT Participation in organized sport and recreational activities presents an innate risk for serious morbidity and mortality. Although death during sport or physical activity has many causes, advancements in sports medicine and evidence-based standards of care have allowed clinicians to prevent, recognize, and treat potentially fatal injuries more effectively. With the continual progress of research and technology, current standards of care are evolving to enhance patient outcomes. In this article, we provided 10 key questions related to the leading causes and treatment of sudden death in sport and physical activity, where future research will support safer participation for athletes and recreational enthusiasts. The current evidence indicates that most deaths can be avoided when proper strategies are in place to prevent occurrence or provide optimal care.