Hydration Strategies Research Articles

Hydration Strategies for Physical Activity and Endurance Events at High (>2500 m) Altitude: A Practical Management Article

A growing number of adventurous athletes are seeking new challenges through endurance events or physical activities held at high altitude (>2500 m). This coincides with a significant increase in the numbers of trekkers who ascend into the world's mountains. Altitude itself influences and complicates the athlete's effective and safe hydration. This article considers the physiology of adaptation to altitude and the effects on hydration at altitude compared with sea level, reviews the "ad libitum versus programmed hydration" controversy in conventional endurance event hydration, examines the evidence for extrapolation of sea level hydration strategies to the high-altitude environment, and synthesizes these disparate factors into a set of practical recommendations for hydration management during high-altitude physical activity. The guidelines will be relevant to participants of physical activity at altitude and health care staff who may care for them in the preparation or performance phases of their adventure.

Hydration and cooling in elite athletes: relationship with performance, body mass loss and body temperatures during the Doha 2019 IAAF World Athletics Championships

PurposeTo characterise hydration, cooling, body mass loss, and core (Tcore) and skin (Tsk) temperatures during World Athletics Championships in hot-humid conditions.MethodsMarathon and race-walk (20 km and 50 km) athletes (n=83,...

Effect of Dehydration on The Development of Endurance and Vertical Elasticity in High-level Basketball Players

Aim: The objective of this study is to observe and verify the effect of dehydration in relation to the performance of physical abilities of endurance and vertical elasticity among high-level basketball players and compare them to the various studies that have been carried out so far and provide adequate recommendations for a dual objective, to achieve performance and preserve the athlete's health. Methods: This study followed a quantitative descriptive research design. We performed tests and re-tests of vertical elasticity through the Squat Jump (SJ) test for the same group being normally hydrated and being dehydrated (on an empty stomach). Then, we followed up with the ½ cooper tests and re-tests for endurance evaluation for the same group being normally hydrated and being dehydrated (fasting). Comparison between the different tests during the three periods of the season. Results: For the first set of results related to the Squat Jump throughout the three periods, we recorded a slight difference but statistically significant between the tests for the two states of hydration. The second sets of results related to the half Cooper were even more confirming and endorsing the first set of results. During the three We recorded statistically significant difference the two states of hydrations, with P value <0.001. Conclusion: Through this study, we observed the effect of dehydration on specific physical abilities in our basketball players. It has been found that dehydration negatively affects the development of their physical abilities. This leads to the implementation of individualization of hydration strategies.

The 4R's Framework of Nutritional Strategies for Post-Exercise Recovery: A Review with Emphasis on New Generation of Carbohydrates.

Post-exercise recovery is a broad term that refers to the restoration of training capacity. After training or competition, there is fatigue accumulation and a reduction in sports performance. In the hours and days following training, the body recovers and performance is expected to return to normal or improve. ScienceDirect, PubMed/MEDLINE, and Google Scholar databases were reviewed to identify studies and position declarations examining the relationship between nutrition and sports recovery. As an evidence-based framework, a 4R’s approach to optimizing post-exercise recovery was identified: (i) Rehydration—a fundamental process that will depend on the athlete, environment and sports event; (ii) Refuel—the consumption of carbohydrates is not only important to replenish the glycogen reserves but also to contribute to the energy requirements for the immune system and tissue reparation. Several bioengineered carbohydrates were discussed but further research is needed; (iii) Repair—post-exercise ingestion of high-quality protein and creatine monohydrate benefit the tissue growth and repair; and (iv) Rest—pre-sleep nutrition has a restorative effect that facilitates the recovery of the musculoskeletal, endocrine, immune, and nervous systems. Nutritional consultancy based on the 4R’s is important for the wise stewardship of the hydration, feeding, and supplementation strategies to achieve a timely recovery.

Skin-interfaced microfluidic system with personalized sweating rate and sweat chloride analytics for sports science applications.

Advanced capabilities in noninvasive, in situ monitoring of sweating rate and sweat electrolyte losses could enable real-time personalized fluid-electrolyte intake recommendations. Established sweat analysis techniques using absorbent patches require post-collection harvesting and benchtop analysis of sweat and are thus impractical for ambulatory use. Here, we introduce a skin-interfaced wearable microfluidic device and smartphone image processing platform that enable analysis of regional sweating rate and sweat chloride concentration ([Cl-]). Systematic studies (n = 312 athletes) establish significant correlations for regional sweating rate and sweat [Cl-] in a controlled environment and during competitive sports under varying environmental conditions. The regional sweating rate and sweat [Cl-] results serve as inputs to algorithms implemented on a smartphone software application that predicts whole-body sweating rate and sweat [Cl-]. This low-cost wearable sensing approach could improve the accessibility of physiological insights available to sports scientists, practitioners, and athletes to inform hydration strategies in real-world ambulatory settings.

Effects of Field Position on Fluid Balance and Electrolyte Losses in Collegiate Women's Soccer Players.

Background and objectives: Research investigating hydration strategies specialized for women’s soccer players is limited, despite the growth in the sport. The purpose of this study was to determine the effects of fluid balance and electrolyte losses in collegiate women’s soccer players. Materials and Methods: Eighteen NCAA Division I women’s soccer players were recruited (age: 19.2 ± 1.0 yr; weight: 68.5 ± 9.0 kg, and height: 168.4 ± 6.7 cm; mean ± SD), including: 3 forwards (FW), 7 mid-fielders (MD), 5 defenders (DF), and 3 goalkeepers (GK). Players practiced outdoor during spring off-season training camp for a total 14 practices (WBGT: 18.3 ± 3.1 °C). The main outcome measures included body mass change (BMC), sweat rate, urine and sweat electrolyte concentrations, and fluid intake. Results: Results were analyzed for comparison between low (LOW; 16.2 ± 2.6° C, n = 7) and moderate risk environments for hyperthermia (MOD; 20.5 ± 1.5 °C, n = 7) as well as by field position. The majority (54%) of players were in a hypohydrated state prior to practice. Overall, 26.7% of players had a %BMC greater than 0%, 71.4% of players had a %BMC less than −2%, and 1.9% of players had a %BMC greater than −2% (all MD position). Mean %BMC and sweat rate in all environmental conditions were −0.4 ± 0.4 kg (−0.5 ± 0.6% body mass) and 1.03 ± 0.21 mg·cm−2·min−1, respectively. In the MOD environment, players exhibited a greater sweat rate (1.07 ± 0.22 mg·cm−2·min−1) compared to LOW (0.99 ± 0.22 mg·cm−2·min−1; p = 0.02). By position, DF had a greater total fluid intake and a lower %BMC compared to FW, MD, and GK (all p < 0.001). FW had a greater sweat sodium (Na+) (51.4 ± 9.8 mmol·L−1), whereas GK had the lowest sweat sodium (Na+) (30.9 ± 3.9 mmol·L−1). Conclusions: Hydration strategies should target pre-practice to ensure players are adequately hydrated. Environments deemed to be of moderate risk of hyperthermia significantly elevated the sweat rate but did not influence fluid intake and hydration status compared to low-risk environments. Given the differences in fluid balance and sweat responses, recommendations should be issued relative to soccer position.

Functional trade-off of hydration strategies in old forest epiphytic cephalolichens

Although water is essential for photosynthetic activation in lichens, rates of vapor uptake and activation in humid air, which likely influence their niche preferences and distribution ranges, are insufficiently known. This study simultaneously quantifies rehydration kinetics and PSII reactivation in sympatric, yet morphologically and functionally distinct cephalolichens (Lobaria amplissima, Lobaria pulmonaria, Lobaria virens). High-temporal resolution monitoring of rehydrating thalli by automatic weighing combined with chlorophyll fluorescence imaging of maximal PSII efficiency (FV/FM) was applied to determine species-specific rates of vapor uptake and photosynthetic activation. The thin and loosely attached growth form of L. pulmonaria rehydrates and reactivates faster in humid air than the thick L. amplissima, with L. virens in between. This flexible hydration strategy is consistent with L. pulmonaria’s wide geographical distribution stretching from rainforests to continental forests. By contrast, the thick and resupinate L. amplissima reactivates slowly in humid air but stores much water when provided in abundance. This prolongs active periods after rain, which could represent an advantage where abundant rain and stem flow alternates with long-lasting drying. Understanding links between morphological traits and functional responses, and their ecological implications for species at risk, is crucial to conservation planning and for modelling populations under various climate scenarios.

Electrolyte Balance And Hydration Status During Wildland Fire Suppression

INTRODUCTION: Our laboratory has previously demonstrated the total energy fluid demands of wildland firefighters (WLFF) during arduous fire suppression. However, it remains unclear how current hydration strategies, occupational activity, and fire line provisions may alter overall hydration and electrolyte balance. PURPOSE: To determine WLFF fluid retention and urine production as influenced by environmental conditions, self-selected hydration practices, and work output during fire suppressions shifts. METHODS: 59 WLFF (9 female, 50 male; 29±6 yr) from various crew types were deployed to fire incidents across the United States during the 2019 fire season and were observed throughout a single work shift. Before and after shifts, a measure of nude body weight was obtained. In a subset of subjects (n=25), pre and post-shift blood samples were also drawn to evaluate serum electrolytes. Fireline-certified researchers monitored fluid intake and urine output parameters (frequency, specific gravity [USG], volume) in real-time via observational data capture using graduated cylinder, refractometer, and mobile tablets. Dependent t-tests were performed for all comparative analyses and statistical significance was established at p<0.05. RESULTS: WLFF worked shifts of 13.9±1.1 hr, during which 4.7±1.6 L of water was consumed. WLFF eliminated 2.3±1.1 L via 5.7±2.7 voids (412±192 mL.void-1). There were no noted differences in USG from morning voids compared to those measured post meridiem (1.0106±0.0147 and 1.0106±0.0187 for AM and PM USG, respectively; p>0.05). No changes in nude body weight were observed across the work shift (80±13.4 and 79.8±13.2 kg for pre- and post-shift, respectively; p>0.05). Serum sodium and potassium did not change between pre- and post-shift blood draws (pre = 142±2 and 4.3±0.3, post = 141±2 and 4.2±0.3, respectively; p>0.05). CONCLUSION: These results demonstrate adequate fireline electrolyte provisions and currently employed WLFF hydration strategies. Moreover, the uniformity of pre- and post-shift measures (body weight, serum electrolytes) demonstrates that USG alone is not adequately indicative of hydration status during extended occupational stress.

Gender Differences Of Sweat Rates In Endurance Trained Athletes

Adequate fluid replacement around exercise is an important consideration for endurance athletes. While sex-based differences in maximal sweat rate have been identified, sex-based differences in sweat rate variability between training sessions is less understood. PURPOSE: The purpose of this study was to observe differences in sweat rate in endurance-trained males and females. METHODS: Endurance-trained males (n=4) and females (n=14) completed training sessions lasting a minimum of 30 minutes once per week. Body mass was collected before and immediately after exercise. Total sweat loss (TSL) was calculated from changes in body mass. TSL and duration of exercise were used to calculate absolute sweat rate (ASR), and subsequently relative sweat rate (RSR). Heat stress was recorded using a WBGT, with temperatures ranging from 9.21-23.65°C. Data were analyzed using two-sample T-tests to evaluate differences between the maximum ASR and RSR between male and female runners. Significance was set a priori at P<0.05. RESULTS: Males had a significantly higher ASR than females (1.46±0.36 vs. 0.89±0.21 L/h; p<0.001). Males and females did not differ for RSR (0.018±0.004 vs. 0.014±0.004 L/kg/h; p=0.116). CONCLUSION: This observational study indicates males had a significantly higher ASR compared to females but similar RSR. Despite lack of significance in RSR, these results correspond with previous studies demonstrating sex differences due to differences in total body surface area. These results suggest sex should be a consideration when implementing different hydration strategies.

Prevalence Of Hypohydration In Military Servicemembers Before A Multi-day Field Training Exercise

It is well established that hypohydration negatively impacts physical and cognitive performance. Despite the importance of hydration, athletes frequently participate in training or competition hypohydrated. While data exists in athletes, there is a lack of data on Military servicemembers’ (SM) hydration status prior to field training exercises or combat. For our nation’s Warfighters, starting a mission hypohydrated can put their lives at risk. Performance decrements can have profound consequences on mission readiness and decrease survivability and lethality on the battlefield. While the recently revalidated Military fluid replacement guidelines (TB MED 507) have been shown to effectively replenish known fluid losses without causing overhydration, they do not address hydration status before training events. PURPOSE: To describe the hydration status of Military SMs prior to a physically rigorous, multi-day field training exercise. METHODS: Data was collected from three training iterations from 2017-2019. In total, first morning void urine samples were collected from 93 Military SMs (2017, n=23; 2018, n=33; 2019, n =37). Hydration status was determined by urine specific gravity (USG) with cutoffs according to the American College of Sports Medicine (ACSM) and the National Athletic Trainers’ Association (NATA) guidelines: euhydration <1.010, minimal hypohydration 1.010-1.020, hypohydration 1.021-1.030, severe hypohydration >1.030. For each cohort, only USG data was collected. RESULTS: The mean (SD) USG for the sample was 1.020 (0.009). Using the ACSM cutoffs (hypohydration >1.020), 50.5% of Military SMs were hypohydrated at the start of the field training exercise. Using the NATA cutoffs, 18.3% (n=17) were euhydrated; 31.2% (n=29) were mildly hypohydrated; 40.9% (n=38) were hypohydrated; 9.7% (n=9) were severely hypohydrated. CONCLUSIONS: Despite the Military’s emphasis on appropriate hydration strategies, just over half of the SM cohort were hypohydrated, while approximately 10% were severely hypohydrated. Future studies need to explore these findings. Although this evidence is preliminary, TB MED 507 may need to be updated to provide specific and clear guidance on strategies for hydration assessment and fluid replenishment prior to participation in operational training events or combat.

INFLUENCE OF HYDRATION STATUS ON RUNNING PERFORMANCE IN HIGH SCHOOL CROSS COUNTRY RUNNERS

Adequate hydration is crucial for athlete's health and performance. Although the impact of hypohydration on professional athletes have been well characterized, there is a dearth of information on the effect of hypohydration on younger populations, such as high school athletes, specifically cross-country runners in a hot and humid environment. PURPOSE: To characterize the effects of hydration status on running performance in high school cross-country runners and determine if a simple hydration plan can improve hydration status. METHODS: 15 high school cross-country runners (9 males, 6 females: 15.5 ± 1.2 yrs) participated in this study. The study took place over a two-week period with baseline testing (V1, V3) and a 5km running performance trials (V2, V4) occurring after school during normal practice hours, with V1 (V3) and V2 (V4) separated by 3 days. A simple hydration strategy of 32oz. of water in the morning and evening preceding the 5km performance trial was implemented to enhance the hydration status of the athletes. Changes in performance between V2 and V4 were determined by 5km completion time, and hydration status was determined by pre- and post-run urine specific gravity using a spectral refractometer. Changes in core temperatures in response to 5km runs were measured on V2 and V4 using core temperature pills. RESULTS: Participants were significantly hypohydrated at rest (USG; V1 = 1.031 ± 0.008, V2 = 1.033 ± 0.006, V3 = 1.030 ± 0.007), but the simple hydration strategy implemented after V3 significantly improved hydration in V4 (resting USG = 1.024 ± 0.008; p<0.001). The average 5km performance times were not significantly different between V2 and V4 (V2:1613.3±224.4 sec, V4:1716.2±176.1 sec), however changes in resting hydration status between V2 and V4 were significantly correlated with improvements in 5km performance time (p=0.02, Pearson’s r=0.63). Changes in core temperature from pre- to post-practice was significantly lower in V2 than V4 (V2:+0.79±0.7 0C, V4:+0.86±1.35 0C; p=0.04). CONCLUSION: High school cross-country runners are hypohydrated, and a simple hydration plan can improve hydration status. Improved hydration was correlated to lower performance times in our cohort of young athletes. The findings support that high school athlete’s hydration status is of concern and should be monitored.

A Randomized Cross-Over Field Study of Pre-Hydration Strategies in Dogs Tracking in Hot Environments.

The objective of this study was to evaluate 4 pre-exercise hydration strategies (oral water, chicken-flavored water, chicken-flavored oral electrolyte solution, and subcutaneous electrolyte solution) in working dogs conducting rigorous tracking operations in hot and arid conditions. In a randomized cross-over field study, 7 Border Patrol Search, Trauma, and Rescue (BORSTAR) Unit dogs working/training out of Fort Bliss in El Paso, Texas were randomly assigned to one of 4 different hydration strategy treatments each day for 4 days of study participation. Dogs were provided hydration treatment prior to running 2 separate one-mile tracks and were offered water while tracking. Body weight, blood, and urine were collected at the beginning of the study day and at the completion of each track. Core body temperatures were recorded using internal temperature sensing capsules. The impact of hydration strategy on change in weight, peak temperature, and serum chemical, hematological, and urinary parameters were analyzed using the COIN procedure in Ra. Compared to the other 3 hydration strategies, dogs receiving chicken-flavored water had higher blood creatine kinase values at the end of the second track (p = 0.0361). Otherwise, hydration strategy had minimal effects on blood or urine parameters. Total fluid intake was lower with water only compared to the other three hydration strategies. Dogs developed elevated core body temperatures (median 41°C; 106°F) without signs of heat exhaustion or heat stroke. Alternate hydration strategies increased total fluid intake compared to water alone; however, chicken-flavored water resulted in increased markers of muscle injury suggesting electrolyte-enriched strategies may have an advantage as a hydration strategy. Additionally, electrolyte-enriched fluids before exercise may help these dogs maintain lower peak temperatures.

Hydration and Cooling Strategies for Paralympic Athletes : Applied Focus: Challenges Athletes May Face at the Upcoming Tokyo Paralympics.

Effective thermoregulation is paramount for optimizing athletic performance and minimizing the risk of heat illness when exercising, especially in hot conditions. Para-athletes can face unique challenges in regard to thermoregulation and hydration, especially when travel is involved. For example, athletes with spinal cord injuries (SCI) have an impaired ability to thermoregulate due to a decreased sweat rate and ability to dissipate heat, thus making vigorous activity in the heat a challenge. These factors may put the athlete at risk for the following: dehydration, overheating, heat exhaustion and stroke, an inability to complete training sessions or competition, cramping, and impaired cognitive function/decision-making, which can lead to increased risk for injury. Therefore, fluid and cooling needs should be periodized and individualized according to the athlete's needs and impairment type. Strategies for cooling, and developing hydration plans for para-athletes will be reviewed.

Novel hydration and nutritional strategies for sickle cell disease.

IntroductionSickle cell disease and sickle cell trait affect over 300 million people worldwide. Vaso‐occlusive crises (VOCs) are the most common reason that these patients seek medical care.ObjectivesRecently, a newly identified “trigger” (involving glucose and electrolytes) for a mechanism of abnormal actin polymerization may offer further understanding with regard to the sequence of events that cascade to complications such as VOCs in those with sickle cell disease (SCD) and as well as those with sickle cell trait.MethodsA literature review to identify the current standard of care guidelines for hydration and nutritional strategies during VOCs in patients with SCD and sickle cell trait was conducted in PubMed, OVID, and Google Scholar.ResultsThis review suggested that current rationales for hydration and nutritional strategies for these patients during periods of crisis are generally based on consensus and have remained largely undefined to date.ConclusionThis new trigger, along with this literature review, suggests investigations related to serum glucose and cation (electrolyte) levels may help define novel strategies for the development of protocols/standard of care with regard to intravenous and oral hydration/nutritional guidelines in these patients during both clinical and perioperative management periods.

Effects of training intensity and environmental condition on the hydration status of elite football players

ABSTRACT Objective: To examine the effects of training intensity and environmental condition on the hydration status of Elite football players. Methods: Eleven elite football players completed three training sessions of varying intensity in cool (12°C) and warm (23°C) environments. Training demands was measured by Global Positioning System, sweat rate and sweat sodium concentration were measured using dermal patches and body mass change. Results: Warm condition increased sweat rate (0.9 ± 0.3 vs 1.7 ± 0.3 L.h-1, P<0.001), fluid intake (0.7 ± 0.1 vs 1.5 ± 0.2 L, P<0.001), total sodium loss (1405 ± 340 vs 2946 ± 958 mg, P<0.001) and total sweat loss (1.4 ± 0.5 vs 2.5 ± 0.4 L, P<0.001) compared to cool. Training intensity increased sweat sodium concentration (16.1 ± 6.6 vs 54.6 ± 22.2 mmol.L-1, P<0.001) and sodium loss (779 ± 231 vs 1405 ± 340 mg) in both environmental conditions. Total sweat loss and sodium loss were positively correlated with total distance covered (r=0.48, P=0.005 and r=0.4, P=0.023, respectively), meanwhile sodium loss was also positively correlated with the total number of high-intensity efforts (r=0.35, P=0.045). Conclusions: The results show that training load and environmental condition have a major impact on the hydration status of elite football players, hence hydration strategies should be developed accordingly.

Dietary Intake, Hydration Status, and Body Composition of Three Belgian Military Groups.

Malnutrition, suboptimal hydration, and inadequate body composition can have negative consequences on soldiers' performance and health. A recent consensus statement concerning "soldiers' physical performance" points to the scarcity of data in specific military populations. Therefore, the aim of the present study was to assess and compare dietary intake, hydration status, and body composition of three military groups during their specific military training. Eighty-five soldiers (ie, 21 in a qualification course to join the Special Forces [SF], 22 Infantrymen [Chasseurs Ardennais, CA], and 42 Recruits [REs]) participated in this 3- to 4-day study. Body mass was assessed before and after each study period. All soldiers self-reported their dietary intakes, from which energy and macronutrient intakes were calculated. In addition, their morning urine samples were collected daily to assess urine specific gravity (USG) as a measure of hydration status. Fat mass was estimated at the end of the study using bioelectrical impedance analysis. All groups lost significant amounts of body mass (ie, mean losses ranging between 1.3 and 1.7kg). Macronutrient intakes were not fully met in respect to the recommendations. Most notably, REs' fat intake was high (ie, 42.3 [±1.6] energy percent [E%]), while their carbohydrate intake was low (ie, 44.5 [±2.1] E%). Furthermore, saturated fat intakes were high among all groups (ie, group means ranging between 13.6 and 21.4 E%). USG values indicated suboptimal hydration status was prevalent in all groups. Most noteworthy, for SF, only 5.4% of the USG values indicated optimal hydration. The average fat mass (%) for SF, CA, and RE was 11.2 (±3.1), 18.8 (±5.1), and 19.4 (±5.0), respectively. The present study showed that military men are not always adequately fed nor hydrated. These issues should be resolved by creating nutritional packages, and individual dietary and hydration strategies, all in function of military planning and weather conditions.

Heat Acclimation with Controlled Heart Rate: Influence of Hydration Status.

This study aimed to characterize the adaptive responses to heat acclimation (HA) with controlled heart rate (HR) and determine whether hydration strategy alters adaptations. The influence of HA on maximal oxygen uptake (V˙O2max) in cool conditions and self-paced exercise in the heat was also determined. Eight men (V˙O2max, 55 ± 7 mL·kg·min) completed two 10-d interventions in a counterbalanced crossover design. Fluid intakes differed between interventions to either maintain euhydration (HA-EUH) or elicit similar daily body mass deficits (2.85% ± 0.26%; HA-DEH). HA consisted of 90 min of cycling in 40°C and 40% relative humidity. Initial workload (172 ± 22 W) was adjusted over the last 75 min to maintain exercising HR equivalent to 65% V˙O2max. A V˙O2max test in cool conditions and 30-min time trial in hot-humid conditions were completed before and after HA. HR at the end of the initial 15 min workload was 10 ± 5 bpm lower on day 10 in both interventions (P < 0.001). The workload necessary to maintain exercising HR (145 ± 7 bpm) increased throughout HA-EUH (25 ± 10 W, P = 0.001) and HA-DEH (16 ± 18 W, P = 0.02). There was a main effect of HA on sweat rate (P = 0.014), which tended to increase with HA-EUH (0.19 ± 0.18 L·h, P = 0.06), but not HA-DEH (P = 0.12). Skin temperature decreased during HA-EUH (0.6°C ± 0.5°C, P = 0.03), but not HA-DEH (P = 0.30). There was a main effect of HA on V˙O2max (~3 mL·kg·min, P = 0.02); however, neither intervention independently increased V˙O2max (both, P = 0.08). Time-trial performance increased after HA-EUH (19 ± 16 W, P = 0.02), but not HA-DEH (P = 0.21). Controlled HR exercise in the heat induces several HA adaptations, which may be optimized by maintaining euhydration. HA-EUH also improves self-paced exercise performance in the heat. However, HA does not seem to significantly increase V˙O2max in cool conditions.

Hydration Strategies for Preventing Contrast-Induced Acute Kidney Injury: A Systematic Review and Bayesian Network Meta-Analysis.

Aims Many previous studies have examined the effect of different hydration strategies on prevention of contrast-induced acute kidney injury (CI-AKI), but the optimal strategy is unknown. We performed a network meta-analysis (NWM) of these previous studies to identify the optimal strategy. Methods and Results Web of Science, PubMed, OVID Medline, and Cochrane Library were searched from their inception dates to September 30, 2018. Randomized controlled trials (RCTs) were selected based on strict inclusion criteria, and a Bayesian NWM was performed using WinBUGS V.1.4.3. We finally analyzed 60 eligible RCTs, which examined 21,293 patients and 2232 CI-AKI events. Compared to intravenous 0.9% sodium chloride (reference), intravenous sodium bicarbonate (OR [95% CI]: 0.74 [0.57, 0.93]), hemodynamic guided hydration (0.41 [0.18, 0.93]), and RenalGuard guided hydration (0.32 [0.14, 0.70]) significantly reduced the occurrence of CI-AKI. Oral hydration and intravenous 0.9% sodium chloride were each noninferior to no hydration in preventing CI-AKI. Intravenous 0.9% sodium chloride, sodium bicarbonate, and hemodynamic guided hydration were each noninferior to oral hydration in preventing CI-AKI. Based on surface under the cumulative ranking curve values, the RenalGuard system was best (0.974) and hemodynamic guided hydration was second best (0.849). Conclusion There was substantial evidence to support the use of RenalGuard or hemodynamic guided hydration for preventing CI-AKI in high-risk patients, especially those with chronic kidney disease or cardiac dysfunction.

Recognizing and treating heat-related illnesses

Background: The increasing frequency of endurance sports events and the associated risk of heat-related illnesses underscore the importance of effective recognition and treatment techniques for emergency medical services (EMS). High-profile incidents involving heat stress, such as those observed in Olympic and Ironman competitions, highlight the need for comprehensive strategies to manage exertional heat illnesses. Aim: This article aims to review current techniques and approaches for recognizing and treating heat-related illnesses via pharmacists, focusing on the implications for EMS during endurance sports events. Methods: A review of historical and recent cases of heat-related illnesses in endurance sports was conducted. This includes analyzing the physiological mechanisms of heat stress, examining the pathophysiology of heat-related injuries, and evaluating current medical guidelines and intervention strategies. Data were gathered from sports medicine literature, international sporting regulations, and recent research studies. Results: The review reveals that effective management of heat-related illnesses requires early recognition of symptoms, understanding the pathophysiology of heat stress, and implementing preventive measures. Key interventions include monitoring environmental conditions using wet globe bulb temperature (WGBT) indices, enforcing temperature limits in event planning, and improving athlete acclimatization and hydration strategies. The effectiveness of these measures varies depending on individual athlete responses and environmental conditions.

Distance Running Special Topic Issue

This special topic issue of Strength and Conditioning Journal is devoted to the sport of distance running. The popularity of running comes as no surprise. The equipment needs are minimal and generally affordable, the skill requirement is not overly challenging, and the opportunity for participation spans the gamut from shorter 5k road races all the way up to ultramarathon trail events and even includes those who run just for the simple joy of being able to get out and move. Even with this simplicity and popularity, those who participate in running benefit from knowing how to optimize performance and reduce injury risk. With that in mind, we have assembled a wide variety of articles to address topics of interest to runners, running coaches, and even those who plan and direct races. Each runner brings a unique set of variables to the mix. The unique needs of youth and adolescent runners require the coaching professional to be sensitive to both training needs and physiological and emotional maturation. Women returning to running postpartum must take into account the structural changes that accompany pregnancy and delivery, the physiological demands of breast feeding, and the time challenges associated with coordinating training and caring for a newborn. Athletes training for races in environmental extremes of either heat or cold should take into account the challenges and opportunities that those conditions present. Strength and conditioning professionals should be aware that eating disorders while more commonly addressed in the context of female runners may also present in male runners and may require a different approach to recognition and resolution. Running injuries, while common, may be favorably affected by specific strength and conditioning interventions or recognition of lower-limb biomechanical factors. Ideal running performance is the result of many factors coming together. Proper pacing strategy, proper hydration strategy, and optimization of parameters such as running economy are crucial in achieving optimum performance in any given race. The potential benefits from running are many. A few include increased aerobic fitness, weight loss, and physiological benefits. However, to obtain these potential benefits, a runner must run, train, or race properly. We recognize that there are numerous running training philosophies. This special topic issue will provide some guidance for someone just beginning to run and/or coach. For the experienced runner or coach, these articles may provide food for thought. In this issue, we have attempted to bring in both scientific evidence as well as practical application from a variety of fields and professions. We hope that the readers will find the topics interesting and informative and that the focus on practical application makes the information especially useful for coaches and athletes alike. We are deeply appreciative of the authors who were willing to contribute their expertise, the reviewers who took the time to offer constructive feedback, and Dr. Jeff Chandler and Dr. Britt Chandler for encouraging and supporting the process along the way. From co-guest editor Janet Hamilton: Thank you, Paul Sorace, for inviting me to join you in this endeavor. It has been a great learning process, and I am honored to have been part of it. From co-guest editor Paul Sorace: I want to thank Janet Hamilton. She is my coguest editor, my coach, and mostly my friend. I could not have done this without you.