Four Cases of Acute Kidney Injury Requiring Dialysis in Ultramarathoners.

Transient acute kidney injury (AKI) following ultraendurance footraces is a common biochemical diagnosis. However, severe AKI requiring renal replacement therapy is uncommon in ultramarathoners. We report 4 runners (3 men; mean age, 44 ± 3 y) who required prolonged (10-42 d) dialysis following the Western States 100 Mile Endurance Run over a 3-y span (0.38% of starters). The maximum ambient temperatures on the race day ranged from 36.6° to 38.3°C. The runners presented to local hospitals 17 to 32 h after running, with laboratories confirming rhabdomyolysis, hyponatremia (mean serum sodium concentration, 127±2 mmol⋅L-1), and AKI (mean serum creatinine concentration, 8.5±2 mg⋅dL-1). The case-cluster report highlights the potential synergistic effects of high ambient temperatures, muscle damage, and electrolyte imbalance on protracted renal dysfunction in ultramarathoners competing in a warming world.

Longitudinal Changes in Fat and Lean Mass: Comparisons between 3D-Infrared and Dual-Energy X-ray Absorptiometry Scans in Athletes.

The low cost and portability of three-dimensional (3D) infrared body scanners make them an attractive tool for body composition measurement in athletes. The main purpose of this study was to compare total body fat percentage (BF%) and total lean mass (LM in kg), in a cohort of collegiate athletes, using a 3D infrared body scanner versus a dual energy x-ray absorptiometry (DXA) scanner. Phase I was a pre-season cross-sectional analysis of 61 (39 male) athletes while Phase II was a longitudinal subset analysis of 38 (27 male) student-athletes who returned to the laboratory for post-season scans (Post minus pre-season change). Both the 3D and DXA scans were performed within 20-minutes of one another in the same room, wearing the same clothing. Paired t-tests were used to compare the mean values (BF% and LM) between measurement devices with estimated effects size calculated using Cohen's d. Data reported as mean±SD. Mean difference (DXA minus 3D) in LM were significantly higher using the 3D scan (5.84 ± 3.55kg; p < 0.001; d = 0.90) compared to the DXA scan, while significantly underestimating BF% (-4.57 ± 4.67%; p < 0.001; d = 1.6) in Phase I analyses. In Phase II analyses, significant differences in the change (post-season minus pre-season change) values were found between methods for LM (4.45 ± 5.04; p < 0.001; d = 0.90), while BF% (-0.41 ± 2.06; p= 0.223; d = 0.2) showed no significant differences. In summary, the 3D and DXA scan values for LM and BF% were not interchangeable in cross-sectional nor longitudinal body composition analyses in collegiate athletes. Close agreement was only observed in longitudinal analyses of BF% and requires further validation with larger cohorts.

Vitamin D supplementation and body composition changes in collegiate basketball players: a 12-week randomized control trial.

Background: Vitamin D promotes bone and muscle growth in non-athletes, suggesting supplementation may be ergogenic in athletes. Our primary aim was to determine if modest Vitamin D supplementation augments favorable body composition changes (increased bone and lean mass and decreased fat mass) and performance in collegiate basketball players following 12 weeks of standardized training. Methods: Members of a men's and women's NCAA D1 Basketball team were recruited. Volunteers were randomized to receive either a weekly 4000 IU Vitamin D3 supplement (D3) or placebo (P) over 12 weeks of standardized pre-season strength training. Pre- and post-measurements included 1) serum 25-hydroxy vitamin D (25(OH)D); 2) body composition variables (total body lean, fat, and bone mass) using dual-energy X-ray absorptiometry (DXA) scans and 3) vertical jump test to assess peak power output. Dietary intake was assessed using Food Frequency questionnaires. Main outcome measures included changes (∆: post-intervention minus pre-intervention) in 25(OH)D, body composition, and performance. Results: Eighteen of the 23 players completed the trial (8 females/10 males). Eight received the placebo (20 ± 1 years; 3 females) while ten received Vitamin D3 (20 ± 2 years; 5 females). Weekly Vitamin D3 supplementation induced non-significant increases (∆) in 25(OH)D (2.6 ± 7.2 vs. -3.5 ± 5.3 ng/mL; p = 0.06), total body bone mineral content (BMC) (73.1 ± 62.5 vs. 84.1 ± 46.5 g; p = 0.68), and total body lean mass (2803.9 ± 1655.4 vs. 4474.5 ± 11,389.8 g; p = 0.03), plus a non-significant change in body fat (-0.5 ± 0.8 vs. -1.1 ± 1.2%; p = 0.19) (Vitamin D3 vs. placebo supplementation groups, respectively). Pre 25(OH)D correlated with both Δ total fat mass (g) (r = 0.65; p = 0.003) and Δ total body fat% (r = 0.56; p = 0.02). No differences were noted in peak power output ∆ between the D3 vs. P group (-127.4 ± 335.4 vs. 50.9 ± 9 W; NS). Participants in the D3 group ingested significantly fewer total calories (-526.2 ± 583.9 vs. -10.0 ± 400 kcals; p = 0.02) than participants in the P group. Conclusions: Modest (~517 IU/day) Vitamin D3 supplementation did not enhance favorable changes in total body composition or performance, over 3 months of training, in collegiate basketball players. Weight training provides a robust training stimulus for bone and lean mass accrual, which likely predominates over isolated supplement use with adequate caloric intakes.

Too Tall for the DXA Scan? Contributions of the Feet and Head to Overall Body Composition.

Accurate assessment of total body composition in tall (>1.96m) individuals using dual energy x-ray absorptiometry (DXA) scans is problematic due to current height restrictions of the scan table. The aim of this investigation was to quantify absolute and relative contributions of fat, bone and lean mass, of the feet and head regions, to whole-body composition DXA scan totals. Whole-body DXA scans were performed in collegiate athletes. Athlete DXA scans were included in data analyses if the entire body fit within the confines of scan table area. The feet region of interest (ROI) was delineated at the ankle joint mortise, marked superiorly by the inferior margin of the tibial plafond and encompassing all inferior anatomical structures. The head region was calculated by the DXA scan software. Both absolute (kg) and relative (feet/whole-body x 100 = feet mass %) contributions to body composition were calculated. Data presented as mean±SD. 132 National Collegiate Athletic Association (NCAA) athletes (85 female) underwent DXA scans which met the inclusion criteria. The feet region represented: 1.9±0.3kg (2.6±0.3%) of total mass; 0.4±0.3kg (2.6±0.5%) of fat mass; 1.3±0.3kg (2.5±0.3%) of lean mass; and 0.14±0.0kg (5.4±0.6%) of bone mineral content (BMC). The head region represented: 4.8±0.5kg (6.9±0.8%) of total mass; 1.2±0.2kg (8.2±3.0%) of fat mass; 3.2±0.5kg (6.1±0.9%) of lean mass; and 0.48±0.07kg (18.7±2.7%) of BMC. Significant negative relationships were found between head% versus whole-body BMC (r=-0.54;p < 0.0001), lean mass (r=-0.57;p<0.0001), and fat mass (r=-0.81;p<0.0001) and between feet% versus fat mass (r=-0.68;p<0.0001). A significant positive relationship was noted between feet% versus whole-body BMC (r=0.18;p=0.04) but not versus lean mass (r=0.15;p=0.09). Removing the feet from whole-body composition analyses reduces lean, fat and bone mass compartment totals by 3%-5%. Removing the head region reduces body composition compartments by 6%-19%, from whole-body DXA scan totals.

Vitamin D in Basketball Players: Current Evidence and Future Directions.

CONTEXT: Despite growing interest in quantifying and correcting vitamin D inadequacy in basketball players, a critical synthesis of these data is yet to be performed to overcome the low generalizability of findings from individual studies. OBJECTIVE: To provide a comprehensive analysis of data in basketball pertaining to (1) the prevalence of vitamin D inadequacy; (2) the effects of vitamin D supplementation on 25-hydroxyvitamin D [25(OH)D] concentration (and its association with body composition), bone health, and performance; and (3) crucial aspects that warrant further investigation. DATA SOURCES: PubMed, MEDLINE, ERIC, Google Scholar, SCIndex, and ScienceDirect databases were searched. STUDY SELECTION: After screening, 15 studies were included in the systematic review and meta-analysis. STUDY DESIGN: Systematic review and meta-analysis. LEVEL OF EVIDENCE: Level 3. DATA EXTRACTION: The prevalence of vitamin D inadequacy, serum 25(OH)D, body composition, stress fractures, and physical performance were extracted. RESULTS: The pooled prevalence of vitamin D inadequacy for 527 basketball players in 14 studies was 77% (P < 0.001; 95% CI, 0.70-0.84). Supplementation with 4000 IU/d and 4000 IU/wk (absolute mean difference [AMD]: 25.39 nmol/L; P < 0.001; 95% CI, 13.44-37.33), as well as 10,000 IU/d (AMD: 100.01; P < 0.001; 95% CI, 70.39-129.63) vitamin D restored 25(OH)D to normal concentrations. Body composition data revealed inverse correlations between changes in serum 25(OH)D (from pre- to postsupplementation) and body fat (r = -0.80; very large). Data concerning positive impacts of vitamin D supplementation on bone health and physical performance remain sparse. CONCLUSION: The high proportion of vitamin D inadequacy underscores the need to screen for serum 25(OH)D in basketball players. Although supplementation restored vitamin D sufficiency, the beneficial effects on bone health and physical performance remain sparse. Adiposity can modulate 25(OH)D response to supplementation.

Incidence of exercise-associated hyponatremia during a high-altitude 161-km ultramarathon.

PURPOSE: Exercise-associated hyponatremia (EAH) is a well-known condition among endurance athletes at low altitudes. The incidence of EAH during ultramarathons at high altitudes warrants further investigation. This prospective observational study was conducted on the participants of the Leadville Trail 100 run, a 161- km race held at a high altitude (2,800 m-3,840 m). METHODS: Venous blood samples were collected before and immediately after the race. The participants completed an electronic survey after the race. Our main outcome measure was the post-race serum sodium ([Na+]) level. RESULTS: Of the 672 athletes who started the race, 351 (52%) successfully completed the event within the 30- hour cut-off. Post-race blood samples were collected from 84 runners (66 finishers). Both pre- and post-race blood samples were collected from 37 participants. Twenty percent of the post-race participants had EAH. Only one post-race participant had a [Na+] level of <130 mmol/L. All participants with EAH were asymptomatic. One participant had an abnormal pre-race [Na+] level (134 mmol/L). Female participants had a significantly higher rate of EAH than male participants (40% vs. 16%; p=0.039). Age, body mass index, weight changes, race completion status, nonsteroidal anti-inflammatory drug use, and urine specific gravity were not associated with the development of EAH. Lower postrace [Na+] levels were associated with higher serum creatine kinase values (R2=0.1, p<0.005). CONCLUSION: High altitude (3,840 m peak) does not appear to enhance the incidence of EAH after an ultramarathon footrace. This suggests that ambient temperature (low temperatures reduce risk), sex (female predilection), endurance running, and overhydration are more prominent risk factors for EAH than high altitude.

Women's Lives Matter-The Critical Need for Women to Prioritize Optimal Physical Activity to Reduce COVID-19 Illness Risk and Severity.

Physical activity (PA) is beneficial for the health and wellness of individuals and societies. During an infectious disease pandemic, such as the one caused by COVID-19, social distancing, quarantines, and lockdowns are used to reduce community spread of the disease. Unfortunately, such nonpharmacological interventions or physical risk mitigation measures also make it challenging to engage in PA. Reduced PA could then trigger physiological changes that affect both mental and physical health. In this regard, women are more likely to experience physical and psychological distress. PA is a safe and effective nonpharmacological modality that can help prevent and manage several mental and physical health problems when performed correctly. PA might even confer benefits that are directly related to decreasing COVID-19 morbidity and mortality in women. In this review, we summarize why optimal PA must be a priority for women during the COVID-19 pandemic. We then discuss chronic COVID-19 illness and its impact on women, which further underscores the need for worldwide preventive health strategies that include PA. Finally, we discuss the importance of vaccination against COVID-19 for women, as part of prioritizing preventive healthcare and an active lifestyle.

Effects of High-Intensity Interval Training Protocols on Liver Enzymes and Wellness in Women.

BACKGROUND: Single-modality, high-intensity interval training (HIIT) using traditional cardiorespiratory exercise selection has been found to provide similar and sometimes superior cardiometabolic effects compared with moderate-intensity continuous training. However, little is known regarding the cardiometabolic and psychosocial effects of HIIT using resistance training modalities. Therefore, this study aims to compare the effects of HIIT using rowing (R-HIIT) and multimodal HIIT (MM-HIIT) using resistance training on liver enzymes, cardiometabolic risk factors, and psychosocial outcomes. METHOD: Recreationally active females with a body mass index <30 kg/m2 (N = 16, 23.0 ± 5.9 years) were randomized into a MM-HIIT or R-HIIT group and completed a 12-week HIIT intervention (ClinicalTrials.gov registration number: https://clinicaltrials.gov/ct2/show/NCT03093441) using principles of social cognitive theory (SCT). Participants completed pre- and postintervention measurements on anthropometrics, resting heart rate, blood pressure, blood measures (lipids, liver enzymes, and glucose), exercise self-efficacy, and perceived wellness. Analysis of covariance was used to examine differences in postintervention measures between groups after controlling for baseline values, waist circumference, and waist-to-height ratio. RESULTS: R-HIIT group had significantly decreased alanine aminotransferase (mean difference = 13.16, P=0.013, effect size (ES) = 0.44, confidence interval (CI) = 3.40 to 22.92) and aspartate aminotransferase (mean difference = 10.79, P=0.024, ES = 0.38, CI = 1.67 to 19.90) levels compared with the M-HIIT group, and the whole group had improved wellness scores (14.72 ± 2.6 to 16.89 ± 2.76, P=0.002). CONCLUSION: R-HIIT may be an effective preventative method for improving liver health in females without obesity. When using principles of SCT, HIIT may enhance overall well-being.

Prospective Observational Study of Weight-based Assessment of Sodium Supplements on Ultramarathon Performance (WASSUP).

BACKGROUND: Sodium supplements are ubiquitous in endurance running, but their impact on performance has been subjected to much debate. The objective of the study was to assess the effect of sodium supplementation as a weight-based predictor of race performance in ultramarathon runners. METHODS: Prospective observational study during an 80 km (50 mi) stage of a 6-stage 250 km (155 mi) ultramarathon in Chile, Patagonia, Namibia, and Mongolia. Finish line hydration status as measured by weight change, point-of-care serum sodium, and questionnaire provided sodium ingestion categories at 33rd percentile and 66th percentile both for weight-adjusted rate and total sodium consumption, then analyzed for significant relationships to race performance, dysnatremia, and hydration. RESULTS: Two hundred sixty-six participants were enrolled, with 217 (82%) with complete sodium supplement rate data, 174 (80%) with finish line sodium, and 161 (74%) with both pre-race weights and total sodium ingestion allowing weight-based analysis. Sodium intake ranged from 131-533 mg/h/kg (2-7.2 gm), with no statistically significant impact on pace, race time, or quintile rank. These outcomes did not change when sodium intake was analyzed as a continuous variable or by sub-group analysis of the 109 (68%) normonatremic runners. When controlled for weight-adjusted sodium intake, performance was poorly correlated with hydration (r = - 0.152, 95% CI - 0.348-0.057). Dehydrated runners outperformed those overhydrated, with 11% of top 25th percentile finishers dehydrated (versus 2.8% overhydrated), with 3.6 min/km faster pace and time 4.6 h faster finishing time. CONCLUSIONS: No association was found between sodium supplement intake and ultramarathon performance. Dehydrated runners were found to have the best performance. This reinforces the message to avoid overhydration.

Muscle Damage, Soreness, and Stress During Preseason Training in Collegiate Swimmers.

BACKGROUND: In 2014, 6 collegiate swimmers were hospitalized for symptomatic exertional rhabdomyolysis. OBJECTIVE: To serially monitor and assess relationships between skeletal muscle membrane disruption, upper body soreness (UBS) and lower body soreness (LBS), and stress during the first 6 weeks (timepoints) of preseason training in collegiate male and female swimmers. DESIGN: Prospective observational study. SETTING: College/university. PARTICIPANTS: Forty swimmers. INDEPENDENT VARIABLES: Upper and lower body soreness rating (0-10); testosterone (T), cortisol (C), and T/C ratio. MAIN OUTCOME MEASURES: Creatine kinase (CK) and myoglobin (over time) versus independent variables. RESULTS: Weekly training load consisted of ∼87% swimming, ∼5% running, and ∼8% weight training, which increased from 15.8 hours to 20.5 total training hours per week over the first 6 weeks of training. Muscle damage in collegiate swimmers was modest and peaked after the first week of training (week 2) for men (CK = 438 ± 259 U/L; P < 0.0001; r2 = 0.28; myoglobin = 47 ± 18 ng/mL; P = 0.001; r2 = 0.22) and women (CK = 446 ± 723 U/L; P < 0.01; r2 = 0.13; myoglobin = 63 ± 140 ng/mL, not significant) with high variability. Data were presented as peak mean ± SD, significant P value, and r2 from repeated-measures analysis of variance. A temporal disconnect was noted between muscle damage and UBS, which peaked at week 5 in both men (5 ± 2; P < 0.0001; r2 = 0.44) and women (6 ± 2; P < 0.0001; r2 = 0.57). The serum cortisol level decreased over time, which peaked at week 1 (baseline) in men (15 ± 6 µg/dL; P = 0.0004; r2 = 0.38) and women (19 ± 10 µg/dL; P < 0.0001; r2 = 0.49). The testosterone level remained unchanged, which promoted an anabolic hormonal environment that peaked at week 6 (increasing T/C ratio) in men (58 ± 32; P = 0.0003; r2 = 0.31) and women (4 ± 3; P = 0.04; r2 = 0.18) despite gradual increases in training and soreness. CONCLUSIONS: Muscle soreness does not parallel muscle membrane disruption. A 1-week "transition" period is required for muscles to adapt to intense/novel training.

Pandemic-Induced Reductions on Swim Training Volume and Performance in Collegiate Swimmers.

The COVID-19 pandemic caused significant training disruptions during the 2020-2021 season, due to lockdowns, quarantines, and strict adherence to the pandemic protocols. The main purpose of this study was to determine how the pandemic training restrictions affected training volume and performance in one collegiate swim team. Cumulative training volume data across a 28-week season were compared between a pandemic (2020-2021) versus non-pandemic (2019-2020) season. The swimmers were categorized into three groups (sprinters, mid-distance, and long-distance) based on their training group. The performance times of 25 swimmers who competed in the regional championships, during both the non-pandemic and pandemic year, were compared via one-way ANOVA. Twenty-six male and 22 female swimmers commenced the 2020-2021 (pandemic) season, with 23% of the swimmers voluntarily opting out. Three COVID-19 cases were confirmed (2%) by the medical staff, with no long-term effects. Significant reductions in the average swim volume were verified in sprinters (32,867 ± 10,135 vs. 14,800 ± 7995 yards; p < 0.001), mid-distance (26,457 ± 10,692 vs. 17,054 ± 9.923 yards; p < 0.001), and long-distance (37,600 ± 14,430 vs. 22,254 ± 14,418 yards; p < 0.001) swimmers (non-pandemic vs. pandemic season, respectively). In the regional performance analyses, the sprinters swam faster (n = 8; -0.5 ± 0.6 s), while the mid-distance (n = 10; 0.17 ± 2.1 s) and long-distance (n = 7; 6.0 ± 4.9 s) swimmers swam slower (F = 11.76; p = 0.0003; r2 = 0.52). Thus, the pandemic caused significant reductions in swim training volume, with sprinters performing better and long-distance swimmers performing worse at the regional championships.

Is Exercise the Best Medicine during a COVID-19 Pandemic? Comment on Constandt, B.; Thibaut, E.; De Bosscher, V.; Scheerder, J.; Ricour, M.; Willem, A. Exercising in Times of Lockdown: An Analysis of the Impact of COVID-19 on Levels and Patterns of Exercise among Adults in Belgium. Int. J. Environ. Res. Public Health 2020, 17, 4144.

From Constandt et al.'s survey of 13,515 Belgium respondents, regular physical activity can be successfully initiated and sustained during a lockdown, with appropriate social distancing measures. Documentation that 77% of highly active people and 58% of low active people exercised as much or more following the institution of a nationwide lockdown was impressive, given that the cases of COVID-19 were accelerating at that time. The Belgian government's central promotion of exercise, to boost both the mental and physical health of the population, likely contributed to the health, tolerance, and ultimate success of lockdown. In this commentary, we wish to pose a follow-up query which highlights the potential detrimental effects of intense exercise (competition) performed without social distancing measures. The proposed graphical abstract elucidates these possible risks, in contrast to the favorable results outlined in Constandt et al.'s study.

Orthostatic Hypotension and Urine Specific Gravity Among Collegiate Athletes.

Introduction The purpose of this study is to describe orthostatic blood pressure (BP) and urine specific gravity (USG) among collegiate athletes and then to examine if correlations between these variables could support use of orthostatic hypotension (OH) measures to screen for dehydration. Methods A prospective observational study was performed using a sample of convenience of collegiate athletes. Athlete's sex and sport were recorded in addition to height, weight, seated and standing BP and USG measured at a pre- and post-season encounter. An OH response was defined as either the systolic BP decreasing ≥ 15 mmHg or the diastolic BP decreasing ≥ 7 mmHg when transitioning from sit to stand. The USG was considered positive for dehydration if >1.020. Descriptive statistics, pairwise t-tests, and the Spearman version of the correlation coefficient were used with statistical significance set at p < 0.05. Results Eighty athletes met inclusion criteria. Six athletes had an OH response during pre-season and three during post-season. Increased frequencies of athletes testing positive for dehydration were identified during the post-season compared to pre-season measures. No significant association was identified between OH and elevated USG. A secondary analysis identified significant associations between athletes with increased height and OH responses and correlations between higher BP and USG. Conclusion This study identified collegiate athletes with pre- and post-season OH as well as athletes with USG measures meeting the threshold for dehydration. While no correlation between OH and USG was identified, findings suggest screening of both BP and hydration status among collegiate athletes may be warranted.

Wilderness Medical Society Clinical Practice Guidelines for the Management of Exercise-Associated Hyponatremia: 2019 Update.

Exercise-associated hyponatremia (EAH) is defined by a serum or plasma sodium concentration below the normal reference range of 135 mmol·L-1 that occurs during or up to 24 h after prolonged physical activity. It is reported to occur in individual physical activities or during organized endurance events conducted in environments in which medical care is limited and often not available, and patient evacuation to definitive care is often greatly delayed. Rapid recognition and appropriate treatment are essential in the severe form to increase the likelihood of a positive outcome. To mitigate the risk of EAH mismanagement, care providers in the prehospital and in hospital settings must differentiate from other causes that present with similar signs and symptoms. EAH most commonly has overlapping signs and symptoms with heat exhaustion and exertional heat stroke. Failure in this regard is a recognized cause of worsened morbidity and mortality. In an effort to produce best practice guidelines for EAH management, the Wilderness Medical Society convened an expert panel in May 2018. The panel was charged with updating the WMS Practice Guidelines for Treatment of Exercise-Associated Hyponatremia published in 2014 using evidence-based guidelines for the prevention, recognition, and treatment of EAH. Recommendations are made based on presenting with symptomatic EAH, particularly when point-of-care blood sodium testing is unavailable in the field. These recommendations are graded on the basis of the quality of supporting evidence and balanced between the benefits and risks/burdens for each parameter according to the methodology stipulated by the American College of Chest Physicians.

Resting Blood Pressure in Collegiate Swimmers During a Competitive Season: A Prospective Observational Study.

Introduction The purpose of this study was to describe and examine differences in resting blood pressure (BP) during an eight-week time frame in the course of the competitive season among collegiate swimmers of varied sexes. Methods A prospective observational study using a sample of convenience of National Collegiate Athletic Association (NCAA) Division 1 female and male swimmers from one university were invited to participate. Blood pressure was measured using standardized methodology at six encounters spaced over eight weeks. Descriptive statistics analyzed demographics, mean BP, and BP classifications. A pairwise t-test analyzed differences in the mean BP and BP classification by sex. The Bonferroni correction was applied given the multiple variables included in the analysis with statistical significance determined to be p≤0.002. Results Thirty-eight swimmers (15 males and 23 females) met the inclusion criteria. Differences between sexes were identified with a higher mean diastolic BP observed in males at the third encounter (p=0.0004) and a higher mean systolic BP observed in males at the sixth encounter (p=0.0002). Four males and four females were identified with a BP classified as stage 1 or 2 hypertension at the first encounter; however, six males and no females met this criterion at the last encounter which was statistically significant (p=0.0004). Conclusions Increased BP from baseline measured for systole, diastole, and BP classifications was significant in male compared to female swimmers. Specifically, divergence in BP by sex first appeared in the diastolic measures at three weeks and in the systolic measures and BP classifications by eight weeks.

Oral Hypertonic Saline Is Effective in Reversing Acute Mild-to-Moderate Symptomatic Exercise-Associated Hyponatremia.

OBJECTIVES: To determine whether oral administration of 3% hypertonic saline (HTS) is as efficacious as intravenous (IV) 3% saline in reversing symptoms of mild-to-moderate symptomatic exercise-associated hyponatremia (EAH) in athletes during and after a long-distance triathlon. DESIGN: Noninferiority, open-label, parallel-group, randomized control trial to IV or oral HTS. We used permuted block randomization with sealed envelopes, containing the word either "oral" or "IV." SETTING: Annual long-distance triathlon (3.8-km swim, 180-km bike, and 42-km run) at Mont-Tremblant, Quebec, Canada. PARTICIPANTS: Twenty race finishers with mild to moderately symptomatic EAH. INDEPENDENT VARIABLES: Age, sex, race finish time, and 9 clinical symptoms. MAIN OUTCOME MEASURES: Time from treatment to discharge. METHODS: We successfully randomized 20 participants to receive either an oral (n = 11) or IV (n = 9) bolus of HTS. We performed venipuncture to measure serum sodium (Na) at presentation to the medical clinic and at time of symptom resolution after the intervention. RESULTS: The average time from treatment to discharge was 75.8 minutes (SD 29.7) for the IV treatment group and 50.3 minutes (SD 26.8) for the oral treatment group (t test, P = 0.02). Serum Na before and after treatment was not significantly different in both groups. There was no difference on presentation between groups in age, sex, or race finish time, both groups presented with an average of 6 symptoms. CONCLUSIONS: Oral HTS is effective in reversing symptoms of mild-to-moderate hyponatremia in EAH.

Of Mice and Men-The Physiology, Psychology, and Pathology of Overhydration.

The detrimental effects of dehydration, to both mental and physical health, are well-described. The potential adverse consequences of overhydration, however, are less understood. The difficulty for most humans to routinely ingest ≥2 liters (L)-or "eight glasses"-of water per day highlights the likely presence of an inhibitory neural circuit which limits the deleterious consequences of overdrinking in mammals but can be consciously overridden in humans. This review summarizes the existing data obtained from both animal (mostly rodent) and human studies regarding the physiology, psychology, and pathology of overhydration. The physiology section will highlight the molecular strength and significance of aquaporin-2 (AQP2) water channel downregulation, in response to chronic anti-diuretic hormone suppression. Absence of the anti-diuretic hormone, arginine vasopressin (AVP), facilitates copious free water urinary excretion (polyuria) in equal volumes to polydipsia to maintain plasma tonicity within normal physiological limits. The psychology section will highlight reasons why humans and rodents may volitionally overdrink, likely in response to anxiety or social isolation whereas polydipsia triggers mesolimbic reward pathways. Lastly, the potential acute (water intoxication) and chronic (urinary bladder distension, ureter dilation and hydronephrosis) pathologies associated with overhydration will be examined largely from the perspective of human case reports and early animal trials.

Ad libitum water consumption prevents exercise-associated hyponatremia and protects against dehydration in soldiers performing a 40-km route-march.

BACKGROUND: It remains unclear if ad libitum water drinking, as a hydration strategy, prevents exercise-associated hyponatremia (EAH) during prolonged exercise. The aim of this study was to determine the incidence of EAH within the broader context of fluid regulation among soldiers performing a 40-km route-march ingesting water ad libitum. METHODS: Twenty-eight healthy male soldiers participated in this observational trial. Pre- and post-exercise body mass, blood and urine samples were collected. Blood samples were assessed for serum sodium ([Na+]), glucose, creatinine, urea nitrogen (BUN), plasma osmolality, creatine kinase (CK), and plasma arginine vasopressin (AVP) concentrations. Plasma volume (PV) was calculated using hematocrit and hemoglobin. Urine samples were analyzed for osmolality and [Na+]. Water intake was assessed by weighing bottles before, during and after the march. The mean relative humidity was 55.7% (21.9-94.3%) and the mean dry bulb temperature was 27.1 °C (19.5 °C - 37.0 °C) during the exercise. RESULTS: Twenty-five soldiers (72 ± 10 kg) (Mean ± SD) completed the march in 09:11 ± 00:43 (hr:min). Participants consumed 736 ± 259 ml/h of water and lost 2.8 ± 0.9 kg (4.0% ± 1.4%, P < 0.05) of body mass. Significant (pre-march vs. post-march; P < 0.05) decreases in serum [Na+] (141 mmol/L vs. 136 mmol/L), plasma osmolality (303 mOsmol/kg H2O vs. 298 mOsmol/kg H2O), and serum creatinine (111 µmol/L vs. 101 µmol/L) and urine [Na+] (168 mmol/L vs. 142 mmol/L), as well as significant increases in plasma AVP (2 pg/ml vs. 11 pg/ml), plasma CK (1423 U/L vs. 3894 U/L) and urine osmolality (1035 mOsmol/kg H2O vs. 1097 mOsmol/kg H2O) were found. The soldier (72 kg) with the lowest post-exercise sodium level completed the march in 08:38. He drank 800 ml/h, lost 2% body mass, and demonstrated (pre-post) increases in plasma osmolality (294-314 mOsmol/kg H2O), BUN (20-30 mg/dl), AVP (2-16 pg/ml) and PV (41%). His urine osmolality decreased from 1114 mOsmol/kg H2O to 1110 mOsmol/kg H2O. No participants finished the route-march with a serum [Na+] indicating hypernatremia (range, 134-143 mmol/L). CONCLUSIONS: Ad libitum drinking resulted in 4% body mass loss with a 2 mmol/L serum [Na+] reduction in conjunction with high urine osmolality (> 1000 mOsmol/kg H2O) and plasma AVP. No single hydration strategy likely prevents EAH, but hypernatremia (cellular dehydration) was not seen despite > 2% body mass losses and high urine osmolality.

Exercise-Associated Hyponatremia.

Exercise-associated hyponatremia (EAH) refers to below-normal serum sodium concentrations [Na+] that develop during exercise. The pathogenesis of EAH is best described as a spectrum ranging between profound polydipsia to modest sweat sodium losses with hypovolemia and relative dilution. Non-osmotic arginine vasopressin (AVP) remains the unifying pathogenic stimulus to abnormal renal water retention in acute symptomatic EAH. Cases of hyponatremia are mostly reported after endurance sports, but are also observed after shorter duration events and in team sport athletes. The signs and symptoms of EAH are vague, and include bloating, vomiting, headache, and altered mental status. A diagnosis of EAH can only be confirmed by a blood test, whereas signs/symptoms guide the most appropriate treatment strategy. Mild-to-moderate EAH (without encephalopathy) can be treated with either fluid restriction or an oral bolus of a hypertonic saline solution. Severe EAH (with encephalopathy) is a life-threatening emergency and should be urgently treated with intravenous 100 mL boluses of 3% saline until the resolution of encephalopathy symptoms. The prevention of EAH is evolutionarily rooted in preventing overdrinking during exercise. Drinking according to the dictates of thirst is the most individualized strategy to prevent life-threatening dysnatremia during exercise, regardless of sport.