Effect of Heat Acclimatization, Heat Acclimation, and Intermittent Heat Training on Maximal Oxygen Uptake.

BACKGROUND: Maximal oxygen uptake (VO2max) is an important determinant of endurance performance. Heat acclimation/acclimatization (HA/HAz) elicits improvements in endurance performance. Upon heat exposure reduction, intermittent heat training (IHT) may alleviate HA/HAz adaptation decay; however, corresponding VO2max responses are unknown. HYPOTHESIS: VO2max is maintained after HAz/HA; IHT mitigates decrements in aerobic power after HAz/HA. STUDY DESIGN: Interventional study. LEVEL OF EVIDENCE: Level 3. METHODS: A total of 27 male endurance runners (mean ± SD; age, 36 ± 12 years; body mass, 73.03 ± 8.97 kg; height, 178.81 ± 6.39 cm) completed VO2max testing at 5 timepoints; baseline, post-HAz, post-HA, and weeks 4 and 8 of IHT (IHT4, IHT8). After baseline testing, participants completed HAz, preceded by 5 days of HA involving exercise to induce hyperthermia for 60 minutes in the heat (ambient temperature, 39.13 ± 1.37°C; relative humidity, 51.08 ± 8.42%). Participants were assigned randomly to 1 of 3 IHT groups: once-weekly, twice-weekly, or no IHT. Differences in VO2max, velocity at VO2max (vVO2), and maximal heart rate (HRmax) at all 5 timepoints were analyzed using repeated-measure analyses of variance with Bonferroni corrections post hoc. RESULTS: No significant VO2max or vVO2 differences were observed between baseline, post-HAz, or post-HA (P = 0.36 and P = 0.09, respectively). No significant group or time effects were identified for VO2max or vVO2 at post-HA, IHT4, and IHT8 (P = 0.67 and P = 0.21, respectively). Significant HRmax differences were observed between baseline and post-HA tests (P < 0.01). No significant group or time HRmax differences shown for post-HA, IHT4, and IHT8 (P = 0.59). CONCLUSION: VO2max was not reduced among endurance runners after HA/HAz and IHT potentially due to participants' similar aerobic training status and high aerobic fitness levels. CLINICAL RELEVANCE: HAz/HA and IHT maintain aerobic power in endurance runners, with HAz/HA procuring reductions in HRmax.

Exertional Heat Stroke Survival at the Falmouth Road Race: 180 New Cases With Expanded Analysis.

CONTEXT: A high number of exertional heat stroke (EHS) cases occur during the Falmouth Road Race. OBJECTIVES: To extend previous analyses of EHS cases during the Falmouth Road Race by assessing or describing (1) EHS and heat exhaustion (HE) incidence rates, (2) EHS outcomes as they relate to survival, (3) the effect of the environment on these outcomes, and (4) how this influences medical provider planning and preparedness. DESIGN: Descriptive epidemiologic study. SETTING: Falmouth Road Race. PATIENTS OR OTHER PARTICIPANTS: Patients with EHS or HE admitted to the medical tent. MAIN OUTCOME MEASURE(S): We obtained 8 years (2012 to 2019) of Falmouth Road Race anonymous EHS and HE medical records. Meteorologic data were collected and analyzed to evaluate the effect of environmental conditions on the heat illness incidence (exertional heat illness [EHI] = EHS + HE). The EHS treatment and outcomes (ie, cooling time, survival, and discharge outcome), number of HE patients, and wet bulb globe temperature (WBGT) for each race were analyzed. RESULTS: A total of 180 EHS and 239 HE cases were identified. Overall incidence rates per 1000 participants were 2.07 for EHS and 2.76 for HE. The EHI incidence rate was 4.83 per 1000 participants. Of the 180 EHS cases, 100% survived, and 20% were transported to the emergency department. The WBGT was strongly correlated with the incidence of both EHS (r2 = 0.904, P = .026) and EHI (r2 = 0.912, P = .023). CONCLUSIONS: This is the second-largest civilian database of EHS cases reported. When combined with the previous dataset of EHS survivors from this race, it amounts to 454 EHS cases resulting in 100% survival. The WBGT remained a strong predictor of EHS and EHI cases. These findings support 100% survival from EHS when patients over a wide range of ages and sexes are treated with cold-water immersion.

Geographic Disparity in Distance to Trauma Care in Secondary Schools across the United States.

CONTEXT: Geographic disparities exist in trauma care (i.e., "trauma center desert") within the United States. An athletic trainer (AT) on-site at secondary schools (SSs) may help enhance collaboration with emergency medical systems and potentially lead to better outcomes following catastrophic injuries. However, access to AT services relative to the location of Level I or II (i.e., tertiary) trauma centers remain unknown. OBJECTIVE: To visualize and describe SSs distance to trauma centers and compare access to AT services across the United States. DESIGN: Cross-sectional study. SETTING: Public and private secondary schools with interscholastic athletics program in the United States. PATIENTS OR OTHER PARTICIPANTS: Survey data obtained through the Athletic Training Locations and Services (ATLAS) project database between September 2019 and April 2023. MAIN OUTCOME MEASURE(S): The minimum distance from each SS to tertiary trauma centers was calculated on Tableau Desktop by geocoding with longitude and latitude. The status and level of AT employment were obtained from ATLAS project database. The odds and percentage of access to AT services were examined by distance ranges. RESULTS: A total of 18,244 SSs were included in the analyses. Seventy-five percent of SSs (n=13,613) were located within 50 miles from tertiary trauma center. The odds of access to AT services were 2.74 [CI: 2.56-2.93] times greater in SSs located within 50 miles from tertiary trauma center (P<0.001). Additionally, SSs located > 60 miles from tertiary trauma center have decreased access to AT services (R2= 0.9192). CONCLUSION: This study highlights geographic disparity in distance to trauma care for SSs in the United States. SSs located > 60 miles from trauma centers were at reduced odds of access to AT services. Identification of geographic trends of AT services relative to the location of tertiary trauma centers is a critical first step to prevent fatal consequences of catastrophic injuries.

Carbon Fiber Insoles Enhance Perception of Performance Despite Variable Objective Outcomes: Specific to the Moderately Active Individual.

Carbon fiber insoles (CFIs) may benefit performance in elite athletes, however, their use in moderately active individuals has been adopted without evidence supporting such enhancements in this population. Fifteen male subjects performed vertical jump (VJ) and repeat treadmill sprint tests before and after a VO2peak while wearing 1) CFIs and 2) control insoles (CON). Subjects completed a subjective survey regarding their perceived performance abilities for both conditions. There were no significant differences between CFIs and CON in VJ height, sprint distance, heart rate following sprints; and rate of oxygen consumption, perceived fatigue, and perceived exertion at 85% of maximal speed (p > 0.05) during the VO2peak. At maximal speed, although there was no difference between conditions in peak rate of oxygen consumption (95%CI [-4.85, 0.21]) and respiratory exchange ratio (95%CI [-0.01, 0.03]), CFIs resulted in a reduced level of perceived fatigue (95%CI [-1, 0]) and perceived exertion (95%CI [-2, 0]) compared to CON. Subjects subjectively reported increased feelings of "propulsion or explosiveness" (p = 0.026) and being able to "perform better while jumping" (p = 0.029) while wearing CFIs. Heightened perceptions of performance enhancements when wearing CFIs indicate, in the moderately active, perceptual benefits could be more influential for determining CFI use.

Access to Athletic Trainers and Emergency Medical Services Activations for Sport-Related Injuries.

CONTEXT: Having athletic trainers (ATs) employed at secondary schools is associated with improved preparedness for sport-related emergencies. The use of emergency medical services (EMS) in settings with different access to athletic training services remains unknown. OBJECTIVE: To compare the incidence of EMS activations for patients with sport-related injuries among zip codes with various levels of access to athletic training services. DESIGN: Descriptive epidemiology study. SETTING: Data were obtained from the National EMS Information System and the Athletic Training Location and Services Project. PATIENTS OR OTHER PARTICIPANTS: Zip codes where 911 EMS activations for sport-related injuries among individuals 13 to 18 years old occurred. MAIN OUTCOME MEASURE(S): Incidence of EMS activations, athletic training service level (no ATs employed [NONE], less than full-time employment [PARTIAL], all ATs employed full time [FULL]), and athletic training employment model (independent contractor [IC], medical or university facility [MUF], school district [SD], mixed employment models [MIX]) for each zip code. RESULTS: The EMS activations were 2.8 ± 3.6 per zip code (range = 1-81, N = 4923). Among zip codes in which at least 1 AT was employed (n = 2228), 3.73% (n = 83) were IC, 38.20% (n = 851) were MUF, 27.24% (n = 607) were SD, and 30.83% (n = 687) were MIX. Compared with SD, MUF had a 10.8% lower incidence of EMS activations (incidence rate ratio [IRR] = 0.892; 95% CI = 0.817, 0.974; P = .010). The IC (IRR = 0.920; 95% CI = 0.758, 1.118; P = .403) and MIX (IRR = 0.996; 95% CI = 0.909, 1.091; P = .932) employment models were not different from the SD model. Service level was calculated for 3834 zip codes, with 19.5% (n = 746) NONE, 46.2% (n = 1771) PARTIAL, and 34.4% (n = 1317) FULL. Compared with NONE, FULL (IRR = 1.416; 95% CI = 1.308, 1.532; P < .001) and PARTIAL (IRR = 1.368; 95% CI = 1.268, 1.476; P < .001) had higher incidences of EMS activations. CONCLUSIONS: Local access to athletic training services was associated with an increased use of EMS for sport-related injuries among secondary school-aged individuals, possibly indicating improved identification and triage of sport-related emergencies in the area. The difference in EMS use among employment models may reflect different policies and procedures for sport-related emergencies.

The Association Between Access to Athletic Trainers and Emergency Medical Services Activations for Sport-Related Injuries.

CONTEXT: Having athletic trainers (ATs) employed at secondary schools is associated with improved preparedness for sport-related emergencies. Utilization of emergency medical services (EMS) with different access to athletic training services remains unknown. OBJECTIVE: Compare the incidence of EMS activations for sport-related injuries between zip-codes with varying access to athletic training services. DESIGN: Descriptive epidemiology study. SETTING: Data were obtained from the National EMS Information System and the Athletic Training Location and Services Project. PATIENTS OR OTHER PARTICIPANTS: Zip-codes where 9-1-1 EMS activations for sport-related injuries among individuals 13-18 years old occurred. MAIN OUTCOME MEASURE(S): Incidence of EMS activations, athletic training service level (NONE, PART, FULL), athletic training employment model (independent contractor, IC; medical or university facility, MUF; school district, SD; mixed employment models, MIX) for each zip-code. RESULTS: There were 2.8±3.5 EMS activations per zip-code (range 1-81, n=4,923). Among zip-codes where at least 1 AT was employed (n=2,228), 3.73% (n=83) were IC, 30.83% (n=687) were MIX, 27.24% (n=607) were SD, and 38.20% (n=851) were MUF. Compared to SD, MUF had a 10.8% lower incidence of EMS activations (95%CI: 0.817, 0.974, p=0.010). IC (IRR: 0.920, 95%CI: 0.758, 1.118, p=0.403) and MIX (IRR: 0.996, 95% CI: 0.909, 1.091, p=0.932) were not significantly different from SD. Service level was calculated for 3,834 zip-codes, with 19.5% (n=746) NONE, 46.2% (n=1,771) PART, and 34.4% (n=1,317) FULL. Compared to NONE, FULL (IRR: 1.416, 95%CI: 1.308, 1.532, p<0.001) and PART (IRR: 1.368, 95%CI: 1.268, 1.476, p<0.001) had higher incidences of EMS activations. CONCLUSIONS: Local access to athletic training services is associated with an increased utilization of EMS for sport-related injuries among secondary school aged individuals, potentially indicative of improved identification and triage of sport-related emergencies the area. The difference in EMS utilization between employment models may represent the presence of different policies and procedures for sport-related emergencies.

Epidemiology of Emergency Medical Services Activations for Sport-Related Injuries in the United States.

Background Literature examining emergency medical services (EMS) activations for sport-related injuries is limited to the pediatric, high school, and collegiate student-athlete populations, excluding older individuals and recreational athletes. The purpose of this study was to examine EMS activations for sport-related injuries using the National EMS Information System Database from 2017-2018. Methods Data were obtained using the National EMS Information System Database from 2017-2018. EMS activations were limited to 9-1-1 responses for individuals aged 3-99 who sustained a sports-related injury. Independent variables included patient age group: pediatric (<18 years old) vs. adult (≥18 years old). Dependent variables were patient age, gender, and chief complaint anatomic location. Frequencies and proportions were calculated for each variable. Injury proportion ratios (IPRs) with 95% confidence intervals were calculated to compare chief complaint anatomic location by age group. Results There were 71,322 sport-related injuries. Patients were 36.6±22.9 years and most (58.1%, n=41,132) were male. Adults had higher proportions of injuries affecting the abdomen (IPR: 2.05, 95%CI: 1.83, 2.31), chest (IPR: 1.90, 95%CI: 1.75, 2.05), general/global (IPR: 1.54, 95%CI: 1.50, 1.58), and genitalia (IPR: 2.40, 95%CI: 1.39, 4.15), and lower proportions of injuries affecting the back (IPR: 0.55, 95%CI: 0.50, 0.60), lower extremity (IPR: 0.63, 95%CI: 0.60, 0.65), upper extremity (IPR: 0.50, 95%CI: 0.47, 0.53), head (IPR: 0.73, 95%CI: 0.70, 0.77), and neck (IPR: 0.18, 95%CI: 0.16, 0.20) compared to pediatric patients. Conclusion Injuries sustained differed between adult and pediatric patients, indicating sport-related emergencies may change across the lifespan. General/global chief complaints likely indicate sport-related injuries affecting multiple anatomic locations and organ systems. Stakeholders planning large or high-risk athletic events should consider arranging standby or dedicated advanced life support units for their events.

Secondary School Athletic Trainers' Experiences With Organizational Conflict: A Comparison Across Employment Models.

CONTEXT: Athletic training is a multifaceted profession characterized by interpersonal relationships and a team approach to care. Collaborative relationships, by nature, open the door to conflict, which has been reported frequently in the collegiate athletic setting. However, secondary school athletic trainers' (ATs') experiences with conflict and pressure in their role are not readily understood. OBJECTIVE: To measure the extent and sources of stress, pressure, and conflict within the secondary school athletic training setting and determine if differences exist across employment characteristics. DESIGN: Cross-sectional study. SETTING: Secondary school athletics. PATIENTS OR OTHER PARTICIPANTS: Secondary school ATs (n = 725, age = 39.8 ± 10.5 years, years certified = 16.7 ± 9.7, years in current role = 10.6 ± 7.8). MAIN OUTCOME MEASURES: Participants were asked to reply to an online questionnaire with quantitative measures pertaining to organizational conflict and workplace dynamic. Employment type (school district employee, school district teacher, medical or university facility, independent contractor) and status (full time, part time) served as independent variables. Likert-scale scores (1 = strongly agree to 5 = strongly disagree; 1 = always to 5 = never) and perceived sources of stress, pressure, and conflict were the dependent variables. Analyses consisted of Kruskal-Wallis tests with Mann-Whitney U post hoc tests and odds ratios to assess associations between variables of interest. RESULTS: We obtained a 15.3% response rate (725/4745). Although the ATs reported experiencing conflict and pressure, these experiences were relatively infrequent and not universal. Compared with part-time ATs, full-time ATs described higher ratings of strong relationships with coaches (P = .003) and principals (P = .002). The most frequently identified sources of conflict were parents (59%) and coaches (53.9%), followed by athletes (32.6%). Full-time ATs were 1.6 times more likely to report experiencing conflict with a coach than part-time ATs (odds ratio = 1.550, 95% CI = 1.037, 2.317; P = .040). CONCLUSIONS: Secondary school ATs' experiences regarding organizational conflict were relatively positive. Instances of pressure and conflict were noted, though relatively infrequently, and these experiences were largely uninfluenced by employment type.

Deaths Among U.S. Air Force Basic Military Trainees, 2008-2020.

INTRODUCTION: The U.S. Air Force (USAF) Basic Military Training (BMT), a rigorous training program for all enlisted members of the USAF, trains roughly 36,000 recruits annually. Transforming civilians into ready warrior airmen has inherent risks to trainee health, which has infrequently included death. While the average death rate at USAF BMT has decreased between 1956 and 2007 due to process improvement and preventive medicine efforts, further review is warranted to examine the deaths that have occurred since the last published period (1997-2007) and to determine the impact policy changes and updates have had on death rates since that time. Therefore, the purpose of this paper is to identify death rates and types from 2008 to 2020, explore policy implementation, and identify areas needing further improvement or modifications to the overall safety, fitness, and health of USAF BMT trainees. MATERIALS AND METHODS: All deaths were examined and reviewed from 2008 through 2020 for trainees attending the USAF BMT using medical records and autopsy reports. Death rates were calculated using the total population of trainees in a given year as well as over the entire 13-year study period. RESULTS: From 2008 to 2020, five deaths occurred among USAF BMT trainees (one cardiac, two exertional sickling due to sickle cell trait, one infection, and one suicide). This resulted in an overall average death rate of 1.08 per 100,000 trainees, as compared to 1.46 per 100,000 from 1997 to 2007. The last death in the study period occurred in 2016. CONCLUSION: A modest downward trend of average death rate has continued since 2007, and no deaths from 2016 through 2020 represents the longest time frame without any deaths at USAF BMT over all times reported (dating back to 1956) which suggest that emergency best practice policies are/have improved. However, cardiac death rate and suicide rate have not changed since the last report. Policies and practices should be continuously reviewed and refined to reduce the risk of death at USAF BMT.

Socioeconomic factors and outcomes from exercise-related sudden cardiac arrest in high school student-athletes in the USA.

OBJECTIVE: Minority student-athletes have a lower survival rate from sudden cardiac arrest (SCA) than non-minority student-athletes. This study examined the relationship between high school indicators of socioeconomic status (SES) and survival in student-athletes with exercise-related SCA. METHODS: High school student-athletes in the USA with exercise-related SCA on school campuses were prospectively identified from 1 July 2014 to 30 June 2018 by the National Center for Catastrophic Sports Injury Research. High school indicators of SES included the following: median household and family income, proportion of students on free/reduced lunch and percent minority students. Resuscitation details included witnessed arrest, presence of an athletic trainer, bystander cardiopulmonary resuscitation and use of an on-site automated external defibrillator (AED). The primary outcome was survival to hospital discharge. Differences in survival were analysed using risk ratios (RR) and univariate general log-binomial regression models. RESULTS: Of 111 cases identified (mean age 15.8 years, 88% male, 49% white non-Hispanic), 75 (68%) survived. Minority student-athletes had a lower survival rate compared with white non-Hispanic student-athletes (51.1% vs 75.9%; RR 0.67, 95% CI 0.49 to 0.92). A non-significant monotonic increase in survival was observed with increasing median household or family income and with decreasing percent minority students or proportion on free/reduced lunch. The survival rate was 83% if an athletic trainer was on-site at the time of SCA and 85% if an on-site AED was used. CONCLUSIONS: Minority student-athletes with exercise-related SCA on high school campuses have lower survival rates than white non-Hispanic athletes, but this difference is not fully explained by SES markers of the school.

Effects of Heat Acclimatization, Heat Acclimation, and Intermittent Exercise Heat Training on Time-Trial Performance.

BACKGROUND: The purpose of this study was to investigate effects of heat acclimatization (HAz) followed by heat acclimation (HA), and intermittent heat training (IHT) on time-trial performance. HYPOTHESIS: Time-trial performance will improve after HA and will further improve with twice a week of IHT. STUDY DESIGN: Interventional study. LEVEL OF EVIDENCE: Level 3. METHODS: A total of 26 male athletes (mean ± SD; age, 35 ± 12 years; body mass, 72.8 ± 8.9 kg; peak oxygen consumption [VO2peak], 57.3 ± 6.7 mL·kg-1·min-1) completed five 4-km time trials (baseline, post-HAz, post-HA, post-IHT4, post-IHT8) in the heat (ambient temperature, 35.4°C ± 0.3°C; relative humidity, 46.7% ± 1.2%) on a motorized treadmill. After baseline time trial, participants performed HAz (109 ± 10 days) followed by post-HAz time trial. Then, participants completed 5 days of HA, which involved exercising to induce hyperthermia (38.50°C-39.75°C) for 60 minutes. Participants were then divided into 3 groups and completed IHT either twice per week (IHTMAX), once per week (IHTMIN), or not at all (IHTCON) over an 8-week period. The exercise used for the IHT matched the HA. Four-kilometer time trials were performed after 4 weeks (post-IHT4) and 8 weeks of IHT (post-IHT8). RESULTS: Time trial was faster in post-HA (17.98 ± 2.51 minutes) compared with baseline (18.61 ± 3.06 minutes; P = 0.037) and post-HAz (18.66 ± 3.12 minutes; P = 0.023). Percentage change in time trial was faster in IHTMAX (-3.9% ± 5.2%) compared with IHTCON (11.5% ± 16.9%) (P = 0.020) and approached statistical significance with large effect (effect size = 0.96) compared with IHTMIN (1.6% ± 6.2%; P = 0.059) at post-IHT8. Additionally, IHTMAX (-2.2% ± 4.2%) was faster than IHTCON (3.6% ± 6.9%) (P = 0.05) at post-IHT4. CONCLUSION: These results indicate that HA after HAz induces additional improvement in time-trial performance. IHT twice per week shows improvement after 8 weeks, while once per week maintains performance for 8 weeks. No IHT results in a loss of adaptations after 4 weeks and even greater losses after 8 weeks. CLINICAL RELEVANCE: HA after HAz improves time-trial performance, twice a week of IHT improves performance further, and once a week of IHT maintains performance for at least 8 weeks.

The efficacy of weekly and bi-weekly heat training to maintain the physiological benefits of heat acclimation.

OBJECTIVES: To examine the efficacy of weekly and bi-weekly heat training to maintain heat acclimatization (HAz) and heat acclimation (HA) for 8 weeks in aerobically trained athletes. DESIGN: Randomized, between-group. METHODS: Twenty-four males (mean [m ±â€¯standard deviation [sd]; (age, 34 ±â€¯12 y; body mass, 72.6 ±â€¯8.8 kg, VO2peak, 57.7 ±â€¯6.8 mL·kg-1·min-1) completed five trials (baseline, following HAz, following HA (HAz + HA), four weeks into heat training [HTWK4], and eight weeks into HT [HTWK8] that involved 60 min of steady-state exercise (59.1 ±â€¯1.8% vVO2peak) in an environmental laboratory (wet bulb globe temperature [WBGT], 29.6 ±â€¯1.4 °C) on a motorized treadmill. Throughout exercise, heart rate (HR) and rectal temperature (Trec) were recorded. Following HAz + HA, participants were assigned to three groups: control group (HT0), once per week heat training (HT1), and twice per week heat training (HT2). HT involved heated exercise (WBGT, 33.3 ±â€¯1.3 °C) to achieve hyperthermia (38.5-39.75 °C) for 60 min. Repeated measures ANOVAs were used to determine differences. RESULTS: HAz + HA resulted in significant improvements in HR (p < 0.001) and Trec (p < 0.001). At HTWK8, HR was significantly higher in HT0 (174 ±â€¯22 beats⋅min-1) compared to HT2 (151 ±â€¯17 beats⋅min-1, p < 0.023), but was not different than HT1 (159 ±â€¯17 beats⋅min-1, p = 0.112). There was no difference in % change of Trec from post-HAz + HA to HTWK4 (0.6 ±â€¯1.3%; p = 0.218), however, HTWK8 (1.8 ±â€¯1.4%) was significantly greater than post-HAz + HA in HT0 (p = 0.009). CONCLUSIONS: Bi-weekly HT provided clear evidence for the ability to maintain physiological adaptions for 8 weeks following HA.

Heat Safety in the Workplace: Modified Delphi Consensus to Establish Strategies and Resources to Protect the US Workers.

The purpose of this consensus document was to develop feasible, evidence-based occupational heat safety recommendations to protect the US workers that experience heat stress. Heat safety recommendations were created to protect worker health and to avoid productivity losses associated with occupational heat stress. Recommendations were tailored to be utilized by safety managers, industrial hygienists, and the employers who bear responsibility for implementing heat safety plans. An interdisciplinary roundtable comprised of 51 experts was assembled to create a narrative review summarizing current data and gaps in knowledge within eight heat safety topics: (a) heat hygiene, (b) hydration, (c) heat acclimatization, (d) environmental monitoring, (e) physiological monitoring, (f) body cooling, (g) textiles and personal protective gear, and (h) emergency action plan implementation. The consensus-based recommendations for each topic were created using the Delphi method and evaluated based on scientific evidence, feasibility, and clarity. The current document presents 40 occupational heat safety recommendations across all eight topics. Establishing these recommendations will help organizations and employers create effective heat safety plans for their workplaces, address factors that limit the implementation of heat safety best-practices and protect worker health and productivity.

Establishing a Global Standard for Wearable Devices in Sport and Exercise Medicine: Perspectives from Academic and Industry Stakeholders.

Millions of consumer sport and fitness wearables (CSFWs) are used worldwide, and millions of datapoints are generated by each device. Moreover, these numbers are rapidly growing, and they contain a heterogeneity of devices, data types, and contexts for data collection. Companies and consumers would benefit from guiding standards on device quality and data formats. To address this growing need, we convened a virtual panel of industry and academic stakeholders, and this manuscript summarizes the outcomes of the discussion. Our objectives were to identify (1) key facilitators of and barriers to participation by CSFW manufacturers in guiding standards and (2) stakeholder priorities. The venues were the Yale Center for Biomedical Data Science Digital Health Monthly Seminar Series (62 participants) and the New England Chapter of the American College of Sports Medicine Annual Meeting (59 participants). In the discussion, stakeholders outlined both facilitators of (e.g., commercial return on investment in device quality, lucrative research partnerships, and transparent and multilevel evaluation of device quality) and barriers (e.g., competitive advantage conflict, lack of flexibility in previously developed devices) to participation in guiding standards. There was general agreement to adopt Keadle et al.'s standard pathway for testing devices (i.e., benchtop, laboratory, field-based, implementation) without consensus on the prioritization of these steps. Overall, there was enthusiasm not to add prescriptive or regulatory steps, but instead create a networking hub that connects companies to consumers and researchers for flexible guidance navigating the heterogeneity, multi-tiered development, dynamicity, and nebulousness of the CSFW field.

The Impact of Environmental Conditions on Player Loads During Preseason Training Sessions in Women's Soccer Athletes.

ABSTRACT: Austin, AB, Collins, SM, Huggins, RA, Smith, BA, and Bowman, TG. The impact of environmental conditions on player loads during preseason training sessions in women's soccer athletes. J Strength Cond Res 35(10): 2775-2782, 2021-Our objective was to determine the impact of environmental conditions on player loads during preseason training sessions in women's soccer athletes. Eleven women's NCAA Division III soccer players (age = 20 ± 1 year, height = 167.28 ± 8.65 cm, body mass = 60.18 ± 5.42 kg, V̇o2max = 43.70 ± 3.95 ml·kg-1·min-1) volunteered to wear Global Positioning System (GPS) devices (Sports Performance Tracking, Melbourne, Australia) that provided measures of training session external intensity throughout all preseason practices (n = 15). We recorded wet-bulb globe temperature (WBGT), session Rating of Perceived Exertion-Training Load (sRPE-TL), and ΔBM during each preseason training session and set α ≤ 0.05. The combination of WBGT, sRPE-TL, and ΔBM explained 34% of the variance in GPS-based intensity score (proprietary measure) (F3,153 = 26.25, p < 0.001). Wet-bulb globe temperature (t156 = -2.58, p = 0.01), sRPE (t156 = 8.24, p < 0.001), and ΔBM (t156 = 2.39, p = 0.02) were significantly associated with intensity. The ΔBM from prepractice (60.00 ± 5.21 kg) to postpractice (59.61 ± 5.10 kg) was statistically significant (p < 0.001); however, ΔBM from the beginning of preseason (59.87 ± 5.31 kg) to the end of preseason (59.91 ± 5.58 kg) was not significant (p = 0.89). Despite relatively low to moderate environmental conditions, increases in WBGT were associated with reductions in GPS intensity and elevated internal load via sRPE-TL. Our findings support the association between exercise intensity and WBGT, internal load, and hydration status; thus, coaches and exercise scientists should take these factors into account when monitoring or interpreting intensity metrics. Furthermore, these findings support the continued use of environmental monitoring and hydration best-practice policies to limit exercise intensity in the heat so as to mitigate excessive heat stress.

Factors Associated With Noncontact Injury in Collegiate Soccer: A 12-Team Prospective Study of NCAA Division I Men's and Women's Soccer.

BACKGROUND: Multiteam, multi-institution prospective studies of both women's and men's sports are essential for collectively investigating injury and primary to the generalization and individualization of injury prevention strategies. HYPOTHESIS: Characteristics of workload, sleep, and contextual factors will be associated with injury risk in collegiate soccer athletes. STUDY DESIGN: Cohort study; Level of evidence, 2. METHODS: Injuries, workload, and sleep characteristics were recorded daily throughout a complete season for 256 athletes from 12 separate National Collegiate Athletic Association Division I men's and women's soccer teams. Workload and contextual factors were assessed via multilevel Poisson regression to capture differences in injury incidence rate ratio (IRR). Paired t test and multilevel logistic regressions were used to assess the relationship between sleep behavior and injury. RESULTS: Collegiate soccer athletes had lower rates of noncontact injury in the in-season (IRR, 0.42) and postseason (IRR, 0.48) compared with preseason, lower rates of injury in training (IRR, 0.64) compared with matches, and higher injury rates with only 1 day of rest in the previous week (IRR, 1.58) compared with >1 day. Injury rates peaked when training occurred 4 days before a match (IRR, 2.24) compared with a match. Injury rate increased exponentially with increases in the number of noncontact injuries incurred throughout the season (IRR, 2.23). Lower chronic loading, higher training monotony, and acute spikes and lulls in workload were associated with higher noncontact injury rates. Alterations in previous week sleep quality were associated with injury, while chronic sleep behavior and acute alterations (<7 days) in sleep behavior were not (P > .05). CONCLUSION: Athlete and schedule-specific contextual factors, combined with characteristics of workload and weekly sleep behavior, are significantly associated with injury in collegiate soccer. Multiteam prospective cohort studies involving objective and subjective monitoring allow for the identification of multiple injury risk factors in sports, which can be used to guide injury prevention strategies. Maintaining higher chronic workloads, lowering training monotony, minimizing acute spikes or lulls in workloads, managing workloads during preseason and for athletes with previous injury, integrating more rest and recovery during congested periods, and optimizing sleep quality are all practical considerations for reducing injury risk in collegiate soccer.

Heat Acclimation Following Heat Acclimatization Elicits Additional Physiological Improvements in Male Endurance Athletes.

The purpose of this study was to assess the effectiveness of heat acclimatization (HAz) followed by heat acclimation (HA) on physiological adaptations. 25 male endurance athletes (age 36 ± 12 y, height 178.8 ± 6.39 cm, body mass 73.03 ± 8.97 kg, and VO2peak 57.5 ± 7.0 mL·kg-1·min-1) completed HAz and HA. HAz was 3 months of self-directed summer training. In the laboratory, a 5-day HA prescribed exercise to target a hyperthermic zone (HZHA) of Trec between 38.50 and 39.75 °C for 60 min. Exercise trials were 60 min of running (59% ± 2% VO2peak) in an environmental chamber (wet bulb globe temperature 29.53 ± 0.63 °C) and administered at: baseline, post-HAz, and post-HAz+HA. Measured variables included internal body temperature (Trec), heart rate (HR), and sweat rate (SR). Repeated measure ANOVAs and post hoc comparisons were used to assess statistically significant (p < 0.05) differences. Trec was lower post-HAz+HA (38.03 ± 0.39 °C) than post-HAz (38.25 ± 0.42 °C, p = 0.009) and baseline (38.29 ± 0.37 °C, p = 0.005). There were no differences between baseline and post-HAz (p = 0.479) in Trec. HR was lower post-HAz (143 ± 12 bpm, p = 0.002) and post-HAz+HA (134 ± 11 bpm, p < 0.001) than baseline (138 ± 14 bpm). HR was lower post-HAz+HA than post-HAz (p = 0.013). SR was higher post-HAz+HA (1.93 ± 0.47 L·h-1) than post-HAz (1.76 ± 0.43 L·h-1, p = 0.027). Combination HAz and HA increased physiological outcomes above HAz. This method can be used to improve performance and safety in addition to HAz alone.

The Relationships Between Perceived Wellness, Sleep, and Acute: Chronic Training Load in National Collegiate Athletics Association Division I Male Soccer Players.

ABSTRACT: Sekiguchi, Y, Curtis, RM, Huggins, RA, Benjamin, CL, Walker, AJ, Arent, SM, Adams, WM, Anderson, T, and Casa, DJ. The relationships between perceived wellness of, sleep of, and acute: chronic training load on National Collegiate Athletics Association division I male soccer players. J Strength Cond Res 35(5): 1326-1330, 2021-The purpose of this study was to investigate relationships between perceived wellness, sleep, and acute: chronic workload ratio (ACWR) throughout a collegiate men's soccer season. Sixty male collegiate soccer players (mean[M] ± SD; age, 21±2 year; body mass, 77.6 ± 6.5 kg; height, 180.1 ± 6.4 cm; body fat%, 9.9 ± 3.9% ; and V̇o2max, 53.1 ± 5.0 ml·kg-1·min-1) participated in this study. During each session, players used a heart rate and global positioning satellite-enabled chest strap to measure training impulse and ACWR. The ACWR values were trichotomized at the individual level giving an equal number of observations within each ACWR category of low, moderate, and high ACWR (M ± SD; low, 0.658 ± 0.23; moderate, 0.92 ± 0.15; and high, 1.17 ± 0.16). Stress, fatigue, and soreness levels were collected using 1-10 Likert scales and sleep duration, and sleep quality were measured by the Karolinska Sleep Diary. Stress, fatigue, soreness levels, and sleep quality were transformed to corresponding z-scores at the individual level. Fatigue levels were significantly higher when ACWR was high compared with low (mean difference [95% confidence intervals], effect size, p-value; 0.31 [0.21, 0.42], 0.29, p < 0.001) and moderate (0.14 [0.03, 0.24], 0.13, p = 0.01). Fatigue levels were also significantly higher when the ACWR was moderate compared with low (0.18 [0.07, 0.28], 0.16, p = 0.001). Soreness levels were significantly higher when the ACWR was high compared with low (0.25 [0.14, 0.36], 0.23, p < 0.001). Stress levels were significantly greater when the ACWR was high compared with low (0.19, [0.08, 0.29], 0.18, p < 0.001) and compared with moderate (0.15, [0.05, 0.25], 0.14, p = 0.004). There were no differences in sleep duration or sleep quality in different ACWR. The ACWR may be a useful tool to achieve an appropriate balance between training and recovery to manage daily fatigue and soreness levels in athletes.

Athletic Training Employment in US Secondary Schools by Geographic Setting and School Size.

CONTEXT: The Athletic Training Locations and Services (ATLAS) Annual Report suggested that athletic trainer (AT) employment status differed based on geographic locale. However, the influence of geographic locale and school size on AT employment is unknown. OBJECTIVE: To determine if differences existed in the odds of having AT services by locale for public and private schools and by student enrollment for public schools. DESIGN: Cross-sectional study. SETTING: Public and private secondary schools with athletics programs. PATIENTS OR OTHER PARTICIPANTS: Data from 20 078 US public and private secondary schools were obtained. MAIN OUTCOME MEASURES(S): Data were collected by the ATLAS Project. Athletic trainer employment status, locale (city, suburban, town, or rural) for public and private schools, and school size category (large, moderate, medium, or small) only for public schools were obtained. The employment status of ATs was examined for each category using odds ratios. Logistic regression analysis produced a prediction model. RESULTS: Of the 19 918 public and private schools with available AT employment status and locale, suburban schools had the highest access to AT services (80.1%) with increased odds compared with rural schools (odds ratio = 3.55 [95% CI = 3.28, 3.85]). Of 15 850 public schools with known AT employment status and student enrollment, large schools had the highest rate of AT services (92.1%) with nearly 18.5 times greater odds (odds ratio = 18.49 [95% CI = 16.20, 21.08]) versus small schools. The logistic model demonstrated that the odds of access to an AT increased by 2.883 times as the school size went up by 1 category. CONCLUSIONS: Nationally, suburban schools and large public schools had the greatest access to AT services compared with schools that were in more remote areas and with lower student enrollment. These findings elucidate the geographic locales and student enrollment levels with the highest prevalence of AT services.