Recommended water immersion duration for the field treatment of exertional heat stroke when rectal temperature is unavailable.

INTRODUCTION: The recommended treatment for exertional heat stroke is immediate, whole-body immersion in < 10 °C water until rectal temperature (Tre) reaches ≤ 38.6 °C. However, real-time Tre assessment is not always feasible or available in field settings or emergency situations. We defined and validated immersion durations for water temperatures of 2-26 °C for treating exertional heat stroke. METHODS: We compiled data for 54 men and 18 women from 7 previous laboratory studies and derived immersion durations for reaching 38.6 °C Tre. The resulting immersion durations were validated against the durations of cold-water immersion used to treat 162 (98 men; 64 women) exertional heat stroke cases at the Falmouth Road Race between 1984 and 2011. RESULTS: Age, height, weight, body surface area, body fat, fat mass, lean body mass, and peak oxygen uptake were weakly associated with the cooling time to a safe Tre of 38.6 °C during immersions to 2-26 °C water (R2 range: 0.00-0.16). Using a specificity criterion of 0.9, receiver operating characteristics curve analysis showed that exertional heat stroke patients must be immersed for 11-12 min when water temperature is ≤ 9 °C, and for 18-19 min when water temperature is 10-26 °C (Cohen's Kappa: 0.32-0.75, p < 0.001; diagnostic odds ratio: 8.63-103.27). CONCLUSION: The reported immersion durations are effective for > 90% of exertional heat stroke patients with pre-immersion Tre of 39.5-42.8 °C. When available, real-time Tre monitoring is the standard of care to accurately diagnose and treat exertional heat stroke, avoiding adverse health outcomes associated with under- or over-cooling, and for implementing cool-first transport second exertional heat stroke policies.

Perceived challenges and barriers for females working in the heat.

Given rising temperatures, globally, heat exposures and catastrophic heat illnesses are a major concern in laborer and industrial sectors. The purpose of this study was to evaluate the perceptions of females laboring in the heat regarding challenges and barriers encountered in their respective industries while working in the heat. A consensual qualitative research (CQR) design was employed to gain information related to participant occupational and job characteristics, feelings while working in the heat, adjustments made by employers when they work in the heat, and their experience working in the heat specific to their identified sex. Females were eligible to participate if they were currently employed in an environment that required them to work in the heat. Twelve females participated in a single, 45-60 min one-on-one semi-structured interview. Participants reported working in the manufacturing, agriculture, tourism, and railroad industries. Upon completion of data analysis, one primary theme was identified: heat stress mitigation strategies, which were further broken down into two subthemes of formal strategies provided by the employer and informal strategies driven by the employees. Participants indicated there was a lack of heat stress prevention strategies implemented by their employers, which resulted in employees creating their own strategies to protect themselves and their coworkers from heat stress. Results indicated there are limited heat stress prevention strategies that are provided in industries that include females working in the heat. Unique considerations should be made to protect this population from the dangers of heat stress and must go beyond workers protecting themselves.

Emergency Medical Planning for an Ultramarathon Open Water Swim: A Case Review of "Swim Tuff".

ABSTRACT: Ultramarathon open water swimming (OWS) events are one of the toughest endurance challenges in the world. The sport has gained notoriety with athletes swimming across the English Channel, Diana Nyad swimming from Cuba to Florida, and the 5- and 10-km OWS in the Olympic schedule. The athletes who participate are exposed to dangerous conditions that expose risks inherent to the sport. The optimal time to prepare for an emergency is before it happens. The aim of this paper is to present an emergency action plan (EAP) designed for the "Swim Tuff" event, a record-breaking ultramarathon swim that took place in Rhode Island, United States. This article identifies an overview of Swim Tuff, the challenges experienced, and how the team designed and implemented risk mitigation strategies. The professionals looking over athletes completing an OWS should be educated and aware of the unique circumstances inherent to the sport.

Comparison between digital and paper urine color to assess hydration status.

PURPOSE: The purpose of this study was to investigate associations between digital urine color and paper urine color with other urine indices to assess hydration status. METHODS: Twelve male subjects (mean ± standard deviation; age, 26 ± 8 years; body mass, 57.8 ± 5.3 kg; height, 177.5 ± 8.9 cm; VO2max, 57.8 ± 5.8 ml·kg-1·min-1) performed four exercise trials in the heat. Before and following exercise trials, subjects provide urine samples. Urine samples were measured using a digital urine color chart on a portable device screen. Urine samples were also assessed with urine specific gravity (USG), urine osmolality (UOsmo), and a validated paper urine color chart. RESULTS: There were extremely large associations found between digital urine color and paper urine color (r = 0.926, p < 0.001). Correlation coefficients showing associations with USG and UOsmo were similar between digital urine color (USG, r = 0.695, p < 0.001; UOsmo, r = 0.555, p < 0.001) and paper urine color (USG, r = 0.713, p < 0.001; UOsmo, r = 0.570, p < 0.001). Bland-Altman analysis indicated that no proportional bias was observed between digital and paper urine colors (bias, - 0.148; SD of bias, 0.492; 95% LOA, - 1.11, 0.817; p = 0.094). CONCLUSIONS: Strong associations were found between digital and paper urine colors with no proportional bias. Furthermore, the degree of associations with USG and UOsmo was similar between digital and paper urine color. These results indicate that digital urine color is a useful tool to assess hydration status and this method could be used as an alternative method to using paper urine color.

Efficacy of two intermittent cooling strategies during prolonged work-rest intervals in the heat with personal protective gear compared with a control condition.

INTRODUCTION: Personal protective equipment (PPE) inhibits heat dissipation and elevates heat strain. Impaired cooling with PPE warrants investigation into practical strategies to improve work capacity and mitigate exertional heat illness. PURPOSE: Examine physiological and subjective effects of forearm immersion (FC), fan mist (MC), and passive cooling (PC) following three intermittent treadmill bouts while wearing PPE. METHODS: Twelve males (27 ± 6 years; 57.6 ± 6.2 ml/kg/min; 78.3 ± 8.1 kg; 183.1 ± 7.2 cm) performed three 50-min (10 min of 40%, 70%, 40%, 60%, 50% vVO2max) treadmill bouts in the heat (36 °C, 30% relative humidity). Thirty minutes of cooling followed each bout, using one of the three strategies per trial. Rectal temperature (Tcore), skin temperature (Tsk), heart rate (HR), heart rate recovery (HRR), rating of perceived exertion (RPE), thirst, thermal sensation (TS), and fatigue were obtained. Repeated-measures analysis of variance (condition x time) detected differences between interventions. RESULTS: Final Tcore was similar between trials (P > .05). Cooling rates were larger in FC and MC vs PC following bout one (P < .05). HRR was greatest in FC following bouts two (P = .013) and three (P < .001). Tsk, fluid consumption, and sweat rate were similar between all trials (P > .05). TS and fatigue during bout three were lower in MC, despite similar Tcore and HR. CONCLUSION: Utilizing FC and MC during intermittent work in the heat with PPE yields some thermoregulatory and cardiovascular benefit, but military health and safety personnel should explore new and novel strategies to mitigate risk and maximize performance under hot conditions while wearing PPE.

Limitations associated with thermoregulation and cardiovascular research assessing laborers performing work in the heat.

PURPOSE: To quantify the current literature and limitations associated with research examining thermoregulatory and cardiovascular strain in laborers working in the heat. METHODS: PubMed, SCOPUS, and SPORTDiscus were searched for terms related to the cardiovascular system, heat stress, and physical work. Qualifying studies included adult participants (18-65 years old), a labor-intensive environment or exercise protocol simulating a labor environment, a minimum duration of 120 min of physical work, and environmental heat stress (ambient temperature ≥26.0°C and ≥30% relative humidity). Studies included at least one of the following outcomes: pre- and peak physical work, core temperature, heart rate (HR), systolic blood pressure, diastolic blood pressure, HR variability, and rate pressure product. RESULTS: Twenty-one out of 1559 potential studies qualified from our search. There was a total of 598 participants (mean = 28 ± 50 participants per study, range = 4-238 participants per study), which included 51 females (8.5%) and 547 males (91.5%). Of the participants, 3.8% had cardiovascular risk factors (diabetes: n = 10; hypertension: n = 13) and 96.2% were characterized as "healthy". Fifty-seven percent of the included studies were performed in a laboratory setting. CONCLUSIONS: Studies were predominantly in men (91.5%), laboratory settings (57%), and "healthy" individuals (96.2%). To advance equity in protection against occupational heat stress and better inform future heat safety recommendations to protect all workers, future studies must focus on addressing these limitations. Employers, supervisors, and other safety stakeholders should consider these limitations while implementing current heat safety recommendations.

IOC consensus statement on recommendations and regulations for sport events in the heat.

This document presents the recommendations developed by the IOC Medical and Scientific Commission and several international federations (IF) on the protection of athletes competing in the heat. It is based on a working group, meetings, field experience and a Delphi process. The first section presents recommendations for event organisers to monitor environmental conditions before and during an event; to provide sufficient ice, shading and cooling; and to work with the IF to remove regulatory and logistical limitations. The second section summarises recommendations that are directly associated with athletes' behaviours, which include the role and methods for heat acclimation; the management of hydration; and adaptation to the warm-up and clothing. The third section explains the specific medical management of exertional heat stroke (EHS) from the field of play triage to the prehospital management in a dedicated heat deck, complementing the usual medical services. The fourth section provides an example for developing an environmental heat risk analysis for sport competitions across all IFs. In summary, while EHS is one of the leading life-threatening conditions for athletes, it is preventable and treatable with the proper risk mitigation and medical response. The protection of athletes competing in the heat involves the close cooperation of the local organising committee, the national and international federations, the athletes and their entourages and the medical team.

Sudden Death in High School Athletes: A Case Series Examining the Influence of Sickle Cell Trait.

ABSTRACT: Athletes with sickle cell trait (SCT) have up to a 37-fold increased risk of exercise-related death. Exertional collapse associated with sickle cell trait (ECAST) is uncommon but can lead to exercise-related death due to exertional sickling. We present a case series of fatal ECAST in high school athletes aged 14 to 16 years. All 3 athletes experienced collapse during practice sessions with muscle pain or weakness. Upon evaluation at the hospital, the athletes had a significant metabolic acidosis that did not respond as expected to fluid resuscitation. Admitting diagnoses for the athletes included exertional heat stroke or dehydration. All 3 athletes had profound rhabdomyolysis leading to acute renal failure, worsening metabolic acidosis, and hyperkalemia. They rapidly progressed to disseminated intravascular coagulation, multiorgan system failure, and death. The autopsies of all 3 athletes showed extensive sickle cell vaso-occlusion involving the spleen liver, and muscles. Final clinical and pathologic diagnosis supported ECAST with fatal exertional rhabdomyolysis. Exertional collapse associated with sickle cell trait is an uncommon but potentially deadly condition that is often underrecognized or misdiagnosed as exertional heat stroke. The development of ECAST is thought to be multifactorial with exercise intensity, recent illness, and exercising conditions (ie, heat and altitude). Prevention should be the primary goal for athletes with SCT through exercise modification, education of precipitation factors, and cessation of exercise with recent illness. Athletes with suspected ECAST should undergo aggressive resuscitation with a low threshold for early transfer to a tertiary care facility for further management and potential hemodialysis.

Countermovement jump, handgrip, and balance performance change during euhydration, mild-dehydration, rehydration, and ad libitum drinking.

Objective: To examine the effects of euhydration, mild-dehydration, rehydration, and ad libitum drinking on countermovement jump (CMJ), handgrip strength, and performance of balance error scoring system test (BESS). Methods: Eighteen healthy male subjects (mean[M]±standard deviation[SD]; age, 23±3y; body mass, 80.1 ± 9.7 kg; height, 175.8 ± 5.7 cm) participated in this study. Participants reported to the laboratory to perform CMJ, handgrip strength, and BESS with different hydration statuses (euhydrated, EUH; when they initially sensed thirst, THIRST; dehydrated, DEH; following 30 minutes of rehydration, REH; and following 24-h ad libitum drinking, AD). Results: CMJ at EUH (M±SD; 54.6 ± 3.0 cm) was significantly higher than DEH (52.8 ± 3.0 cm, p = 0.027) and REH (52.6 ± 2.8 cm, p < 0.001). However, there was no difference between DEH and REH (p = 0.643). CMJ at THIRST (54.9 ± 3.0 cm, p = 0.004) was higher than REH. Also, AD (53.8 ± 2.8 cm, p = 0.027) was higher than REH. In left handgrip strength, THIRST (48.6 ± 9.5 kg) was higher than EUH (46.7 ± 10.1 kg, p = 0.018), DEH (45.8 ± 10.0 kg, p = 0.013), REH (46.1 ± 9.5 kg, p = 0.004), and AD (47.1 ± 9.7 kg, p = 0.05). Additionally, in the single-leg stance on a foam pad, more BESS errors were found at THIRST (6 ± 2) compared to EUH (5 ± 2, p = 0.007) and AD (5 ± 2, p = 0.002). Conclusion: The findings of this study were: ∼2% of mild dehydration induced by 24-h fluid restriction decreased lower body power measured by CMJ, acute rehydration did not restore the loss of lower body power induced by dehydration, and ∼0.5-0.9% of dehydration did not decrease lower body power.

A 3-D virtual human thermoregulatory model to predict whole-body and organ-specific heat-stress responses.

OBJECTIVE: This study aimed at assessing the risks associated with human exposure to heat-stress conditions by predicting organ- and tissue-level heat-stress responses under different exertional activities, environmental conditions, and clothing. METHODS: In this study, we developed an anatomically detailed three-dimensional thermoregulatory finite element model of a 50th percentile U.S. male, to predict the spatiotemporal temperature distribution throughout the body. The model accounts for the major heat transfer and thermoregulatory mechanisms, and circadian-rhythm effects. We validated our model by comparing its temperature predictions of various organs (brain, liver, stomach, bladder, and esophagus), and muscles (vastus medialis and triceps brachii) under normal resting conditions (errors between 0.0 and 0.5 °C), and of rectum under different heat-stress conditions (errors between 0.1 and 0.3 °C), with experimental measurements from multiple studies. RESULTS: Our simulations showed that the rise in the rectal temperature was primarily driven by the activity level (~ 94%) and, to a much lesser extent, environmental conditions or clothing considered in our study. The peak temperature in the heart, liver, and kidney were consistently higher than in the rectum (by ~ 0.6 °C), and the entire heart and liver recorded higher temperatures than in the rectum, indicating that these organs may be more susceptible to heat injury. CONCLUSION: Our model can help assess the impact of exertional and environmental heat stressors at the organ level and, in the future, evaluate the efficacy of different whole-body or localized cooling strategies in preserving organ integrity.

Impact of occupational heat stress on worker productivity and economic cost.

Heat stress is a growing concern in the occupational setting as it endangers worker health, safety, and productivity. Heat-related reductions in physical work capacity and missed workdays directly and indirectly cause productivity losses and may substantially affect the economic wellbeing of the organization. This review highlights the physiological, physical, psychological, and financial harms of heat stress on worker productivity and proposes strategies to quantify heat-related productivity losses. Heat stress produces a vicious-cycle feedback loop that result in adverse outcomes on worker health, safety, and productivity. We propose a theoretical model for implementing an occupational heat safety plan that disrupts this loop, preventing heat-related productivity losses while improving worker health and safety.

Prehospital management of exertional heat stroke at sports competitions: International Olympic Committee Adverse Weather Impact Expert Working Group for the Olympic Games Tokyo 2020.

OBJECTIVES: This document aimed to summarise the key components of exertional heat stroke (EHS) prehospital management. METHODS: Members of the International Olympic Committee Adverse Weather Impact Expert Working Group for the Olympic Games Tokyo 2020 summarised the current best practice regarding the EHS prehospital management. RESULTS: Sports competitions that are scheduled under high environmental heat stress or those that include events with high metabolic demands should implement and adopt policy and procedures for EHS prehospital management. The basic principles of EHS prehospital care are: early recognition, early diagnosis, rapid, on-site cooling and advanced clinical care. In order to achieve these principles, medical organisers must establish an area called the heat deck within or adjacent to the main medical tent that is optimised for EHS diagnosis, treatment and monitoring. Once admitted to the heat deck, the rectal temperature of the athlete with suspected EHS is assessed to confirm an elevated core body temperature. After EHS is diagnosed, the athlete must be cooled on-site until the rectal temperature is below 39°C. While cooling the athlete, medical providers are recommended to conduct a blood analysis to rule out exercise-associated hyponatraemia or hypoglycaemia, provided that this can be safely performed without interrupting cooling. The athlete is transported to advanced care for a full medical evaluation only after the treatment has been provided on-site. CONCLUSIONS: A coordination of care among all medical stakeholders at the sports venue, during transport, and at the hospital is warranted to ensure effective management is provided to the EHS athlete.

Changes in Hydration Factors Over the Course of Heat Acclimation in Endurance Athletes.

The purpose of this study was to examine the effect of heat acclimation (HA) on thirst levels, sweat rate, and percentage of body mass loss (%BML), and changes in fluid intake factors throughout HA induction. Twenty-eight male endurance athletes (mean ± SD; age, 35 ± 12 years; body mass, 73.0 ± 8.9 kg; maximal oxygen consumption, 57.4 ± 6.8 ml·kg-1·min-1) completed 60 min of exercise in a euhydrated state at 58.9 ± 2.3% velocity of maximal oxygen consumption in the heat (ambient temperature, 35.0 ± 1.3 °C; relative humidity, 48.0 ± 1.3%) prior to and following HA where thirst levels, sweat rate, and %BML were measured. Then, participants performed 5 days of HA while held at hyperthermia (38.50-39.75 °C) for 60 min with fluid provided ad libitum. Sweat volume, %BML, thirst levels, and fluid intake were measured for each session. Thirst levels were significantly lower following HA (pre, 4 ± 1; post, 3 ± 1, p < .001). Sweat rate (pre, 1.76 ± 0.42 L/hr; post, 2.00 ± 0.60 L/hr, p = .039) and %BML (pre, 2.66 ± 0.53%; post, 2.98 ± 0.83%, p = .049) were significantly greater following HA. During HA, thirst levels decreased (Day 1, 4 ± 1; Day 2, 3 ± 2; Day 3, 3 ± 2; Day 4, 3 ± 1; Day 5, 3 ± 1; p < .001). However, sweat volume (Day 1, 2.34 ± 0.67 L; Day 2, 2.49 ± 0.58 L; Day 3, 2.67 ± 0.63 L; Day 4, 2.74 ± 0.61 L; Day 5, 2.74 ± 0.91 L; p = .010) and fluid intake (Day 1, 1.20 ± 0.45 L; Day 2, 1.52 ± 0.58 L; Day 3, 1.69 ± 0.63 L; Day 4, 1.65 ± 0.58 L; Day 5, 1.74 ± 0.51 L; p < .001) increased. In conclusion, thirst levels were lower following HA even though sweat rate and %BML were higher. Thirst levels decreased while sweat volume and fluid intake increased during HA induction. Thus, HA should be one of the factors to consider when planning hydration strategies.

Relationship Between Heart Rate Variability and Acute:Chronic Load Ratio Throughout a Season in NCAA D1 Men's Soccer Players.

ABSTRACT: Sekiguchi, Y, Huggins, RA, Curtis, RM, Benjamin, CL, Adams, WM, Looney, DP, West, CA, and Casa, DJ. Relationship between heart rate variability and acute:chronic load ratio throughout a season in NCAA D1 men's soccer players. J Strength Cond Res 35(4): 1103-1109, 2021-The purpose of this study was twofold: (a) to examine the relationship between heart rate variability (HRV) and acute:chronic workload ratio (ACWR)-based training load (TL) metrics and (b) to examine relationships across various A:C ratio-based TL metrics. Heart rate variability in 23 male college soccer players (mean ± SD; age, 21 ± 1 years; body mass, 80.3 ± 5.8 kg; height, 181.9 ± 6.5 cm; %body fat, 11.9 ± 2.0%; and V̇o2max, 51.9 ± 5.0 ml·kg-1·min-1) was measured at 5 time points: week(W)1, W3, W7, W12, and W14 during the 2015 NCAA men's soccer season. Heart rate variability was calculated from beat to beat intervals using a heart rate monitor. Players donned a global position satellite-enabled device that measured the following TL metrics: session time (ST), Player Load (PL), PL·min-1, and total distance (TD). Acute:chronic workload ratio was calculated for each TL metric: ACWR-based ST (ACWRST), ACWR-based PL (ACWRPL), ACWR-based PL·min-1 (ACWRPLM), and ACWR-based TD (ACWRTD): ACWR = week average TLs/mo average (30 ± 1 days) TLs. Relationships between HRV and ACWR-based each TL metric were evaluated using mixed effects models. Tukey pairwise comparisons were used to examine differences between types of ACWR-based TL metrics. An increase in ACWRST significantly reduced HRV throughout a season (-7.4 ± 3.6 m·s-1; p = 0.04). There were significant differences between ACWRPLM and ACWRST, ACWRPL and ACWRTD at W1, ACWRPLM and ACWRST at W3 (p < 0.05). In conclusion, ACWRST, ACWRPL, and ACWRTD were significantly different from ACWRPLM. ACWRST was found to significantly predict HRV; higher ACWRST was significantly associated with lower HRV. Therefore, tracking of the ACWR using ST may help to optimize athlete's physiological state throughout a season.

Seasonal Accumulated Workloads in Collegiate Men's Soccer: A Comparison of Starters and Reserves.

ABSTRACT: Curtis, RM, Huggins, RA, Benjamin, CL, Sekiguchi, Y, Arent, S, Armwald, B, Pullara, JM, West, CA, and Casa, DJ. Seasonal accumulated workloads in collegiate men's soccer: a comparison of starters and reserves. J Strength Cond Res 35(11): 3184-3189, 2021-The purpose of this investigation was to quantify and compare player's season total-, match-, and training-accumulated workload by player status characteristics (i.e., starter vs. reserve) in American collegiate men's soccer. Global positioning system (GPS) and heart rate (HR)-derived workloads were analyzed from 82 collegiate male soccer athletes from 5 separate teams over the 2016 and 2017 seasons. Differences in total physical and physiological workloads (i.e., total distance, accelerations, and weighted HR-zone training impulse [TRIMP] score) as well as workloads over a range of intensity zones were examined using multilevel mixed models, with mean difference (MD) and effect size (ES) reported. Starters accumulated substantially more total distance (MD = 82 km, ES = 1.23), TRIMP (MD = 2,210 au, ES = 0.63), and total accelerations (MD = 6,324 n, ES = 0.66) over the season. Total accumulated distance in all velocity zones (ES [range] = 0.87-1.08), all accelerations zones (ES [range] = 0.54-0.74), and time spent at 70-90% HRmax (ES [range] = 0.60-1.12) was also greater for starters. Reserves accumulated substantially more total distance (MD = 20 km, ES = 0.43) and TRIMP (MD = 1,683 au, ES = 0.79) during training. Although reserves show elevated physical and physiological loads during training compared with starters, there is an imbalance in overall workloads between player roles, with starters incurring substantially more match and total seasonal workloads. These results indicate managing player workloads in soccer requires attention to potential imbalances between players receiving variable match times. Coaches and practitioners in collegiate men's soccer may consider implementing strategies to reduce discrepancies in loading between starters and reserves. Individualized monitoring of training and match workloads may assist in the implementation of more balanced load management programs.

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.

Effects of sex and menstrual cycle on volume-regulatory responses to 24-h fluid restriction.

Reproductive hormones have significant nonreproductive physiological effects, including altering fluid regulation. Our purpose was to explore the impact of sex and menstrual cycle (MC) phase on volume-regulatory responses to 24-h fluid restriction (24-h FR). Participants (men: n = 12, 20 ± 2 yr; women: n = 10, 20 ± 1 yr) were assigned two randomized and counterbalanced fluid prescriptions [Euhy: euhydrated, urine specific gravity (USG) < 1.020; Dehy: 24-h FR, USG > 1.020]. Men completed both (MEuhy, MDehy), while women completed both in the late-follicular (days 10-13; FDehy, FEuhy) and midluteal (days 18-22; LDehy, LEuhy) phases. We measured body mass, plasma and urine osmolality (Posm, Uosm), urine specific gravity (USG), urine color (Ucol), and serum copeptin; 24-h FR yielded mild dehydration without influence of sex or MC (P > 0.05). Copeptin increased in men following Dehy (pre: 8.2 ± 5.2, post: 15.8 ± 12.6, P = 0.04) but not in women (FDehy pre: 4.3 ± 1.6, post: 10.5 ± 6.9, P = 0.06; LDehy pre: 5.6 ± 3.5, post: 10.4 ± 6.2, P = 0.16). In FDehy, Posm increased following FR (pre: 288 ± 2, post: 292 ± 1, P = 0.03) but not in men (pre: 292 ± 3, post: 293 ± 2, P = 0.46). No MC differences were observed between body mass loss, Posm, Uosm, USG, and copeptin (P > 0.05). These results suggest that volume-regulatory responses to 24-h FR were present in men but not in women, without apparent effects of the menstrual cycle.

The Relationship between %BML, Urine Color, Thirst Level and Urine Indices of Hydration Status.

INTRODUCTION: Dehydration is known to impair health, quality of daily life, and exercise performance [1]. While several methods are utilized to assess fluid balance, there is no gold standard to assess hydration status [2]. Cheuvront and Kenefick [3] suggested the use of a Venn diagram, which consists of % body mass weight (BML), urine color, and thirst level (WUT) to measure hydration status and fluid needs. However, no study to date has examined the relationship between the WUT criteria and hydration status measured by urine indices. OBJECTIVE: The purpose of this study was to investigate the relationships between urine-specific gravity (USG), urine osmolality (UOSM), and the WUT criteria. METHODS: Twenty-two females (mean ± SD; age, 20 ± 1 year; weight, 65.4 ± 12.6 kg) and twenty-one males (age, 21 ± 1 year; body mass, 78.7 ± 14.6 kg) participated in this study. First-morning body mass, urine color, USG, UOSM, and thirst level were collected for 10 consecutive days. First 3 days were utilized to establish a euhydrated baseline body weight. %BML >1%, urine color >5, and thirst level ≥5 were used as the dehydration thresholds. The number of markers that indicated dehydration levels was summed when each variable met each threshold. One-way ANOVA with Tukey pairwise comparison was used to assess the differences in USG and UOSM, followed by a calculation of effect size (ES). RESULTS: Figure 1 indicates the differences of UOSM based on the WUT criteria. For UOSM, "2 markers indicated" (mean [M] ± SD [ES], 705 ± 253 mOsmol [0.43], p = 0.018) was significantly higher than "1 marker indicated" (M ± SD, 597 ± 253 mOsmol). Additionally, "zero marker indicated" (509 ± 249 mOsmol) was significantly lower than "3 markers indicated" (M ± SD [ES], 761 ± 250 mOsmol, [1.01], p = 0.02) and "2 markers indicated" ([ES], [0.78], p = 0.004). However, there was no statistical difference between "3 markers indicated" ([ES], [0.65], p = 0.13) and "1 marker indicated." For USG, "3 markers indicated" (M ± SD [ES], 1.021 ± 0.007 [0.57], p = 0.025) and "2 markers indicated" (M ± SD [ES], 1.019 ± 0.010 [0.31], p = 0.026) were significantly higher than "1 marker indicated" (M ± SD, 1.016 ± 0.009). Additionally, "zero marker indicated" (1.014 ± 0.005) was significantly lower than "3 markers indicated" ([ES], [1.21], p = 0.005) and "2 markers indicated" ([ES], [0.54], p = 0.009). CONCLUSION: When 3 markers indicated dehydration levels, UOSM and USG were greater than euhydrated cut points. When 2 markers indicated dehydration levels, USG was higher than the euhydrated cut point. Additionally, UOSM and USG were significantly lower when zero or 1 marker indicated dehydration levels. Thus, the WUT criteria are a useful tool to assess hydration status. Athletes, coaches, sports scientists, and medical professions can use this strategy in the field settings to optimize their performance and health without consuming money and time.

Preventing catastrophic injury and death in collegiate athletes: interassociation recommendations endorsed by 13 medical and sports medicine organisations.

The following organisations endorsed this document: American Association of Neurological Surgeons, American Medical Society for Sports Medicine, American Orthopaedic Society for Sports Medicine, American Osteopathic Academy of Sports Medicine, College Athletic Trainers' Society, Collegiate Strength and Conditioning Coaches Association, Congress of Neurological Surgeons, Korey Stringer Institute, National Athletic Trainers' Association, National Strength and Conditioning Association, National Operating Committee for Standards on Athletic Equipment, Sports Neuropsychology Society. The following organisation has affirmed the value of this document: American Academy of Neurology. The Second Safety in College Football Summit resulted in interassociation consensus recommendations for three paramount safety issues in collegiate athletics: (1) independent medical care for collegiate athletes; (2) diagnosis and management of sport-related concussion; and (3) year-round football practice contact for collegiate athletes. This document, the fourth arising from the 2016 event, addresses the prevention of catastrophic injury, including traumatic and non-traumatic death, in collegiate athletes. The final recommendations in this document are the result of presentations and discussions on key items that occurred at the summit. After those presentations and discussions, endorsing organisation representatives agreed on 18 foundational statements that became the basis for this consensus paper that has been subsequently reviewed by relevant stakeholders and endorsing organisations. This is the final endorsed document for preventing catastrophic injury and death in collegiate athletes. This document is divided into the following components. (1) Background-this section provides an overview of catastrophic injury and death in collegiate athletes. (2) Interassociation recommendations: preventing catastrophic injury and death in collegiate athletes-this section provides the final recommendations of the medical organisations for preventing catastrophic injuries in collegiate athletes. (3) Interassociation recommendations: checklist-this section provides a checklist for each member school. The checklist statements stem from foundational statements voted on by representatives of medical organisations during the summit, and they serve as the primary vehicle for each member school to implement the prevention recommendations. (4) References-this section provides the relevant references for this document. (5) Appendices-this section lists the foundational statements, agenda, summit attendees and medical organisations that endorsed this document.

Environmental Conditions, Preseason Fitness Levels, and Game Workload: Analysis of a Female NCAA DI National Championship Soccer Season.

Benjamin, CL, Hosokawa, Y, Curtis, RM, Schaefer, DA, Bergin, RT, Abegg, MR, and Casa, DJ. Environmental conditions, preseason fitness levels, and game workload: Analysis of a female NCAA DI National Championship Soccer Season. J Strength Cond Res 34(4): 988-994, 2020-The purpose of this study was to determine the independent and combined moderating effect of aerobic fitness and environmental conditions on physical workloads during collegiate female soccer matches. Nineteen National Collegiate Athletic Association female soccer athletes were included in this study (mean ± SD: age, 20.6 ± 1.4 years; height, 169 ± 6.1 cm; body mass 64.7 ± 5.3 kg). Maximal oxygen consumption (V[Combining Dot Above]O2max) was estimated from the yo-yo intermittent recovery test before preseason training and wet-bulb globe temperature (WBGT) was recorded onsite for home matches and at the nearest weather station for away matches. Relative distance (TD), relative high-speed running distance (%HSD), and relative high metabolic load (%HML) performance were collected during each match using a global positioning system unit (Viper Pod; STATSports, Chicago, IL). Statistically significant differences were observed in TD between LOW WBGT and MOD WBGT (mean difference [MD] = 7.08 m·min; effect size [ES] = 0.54; p < 0.001), in %HSD between LOW WBGT and MOD WBGT (MD = 1.97%; ES = 0.64; p = 0.01) and between LOW WBGT and HIGH WBGT (MD = 2.71%; ES = 1.01; p < 0.001), and in %HML between LOW WBGT and MOD WBGT (MD = 1.24%; ES = 0.56; p < 0.001) and between LOW WBGT and HIGH WBGT (MD = 1.55%; ES = 0.78; p = 0.01). There was a significant interaction between WBGT and V[Combining Dot Above]O2max for %HSD (p = 0.03). These findings demonstrate that physical performance metrics were affected by increased WBGT. In addition, aerobic fitness seemed to moderate the effect of increasing WBGT on %HSD, meaning maximizing aerobic capacity is important for optimizing running performance in the heat. Coaches and sports medicine staff could alter training time and session length based on environmental conditions as well as potentially use aggressive cooling strategies to mitigate the imposed heat stress and decrements in physical performance.