The skin of a person weighing 70 kg contains

Methods to Evlute Eletrolyte nd Wter Turnover of Athletes Lwrene E. Armstrong, PhD, FACSM; nd Dougls J. Cs, PhD, ATC, FACSM, FNATA ABSTRACT Fluid-eletrolyte defiienies my umulte over severl dys in thletes whose diets ontin nutrients (eg, wter, sodium, potssium) in quntities tht re smller thn the losses tht our in swet nd urine. Individulized ssessment nd personlized dietry reommendtions re neessry, espeilly in ses of wter or slt depletion, het exhustion, nd het rmps. Unfortuntely, no omposite soure of these tehniques exists. The purpose of this rtile is to desrie methods tht vlidly ssess urine nd swet volumes, eletrolyte onentrtions, dietry fluid nd eletrolyte intke, nd 24-hour wter nd eletrolyte lne for thletes who trin nd ompete in hot environments. Referene (ie, expeted) vlues, smple dt sheets, nd se report re presented. These tehniques llow motivted professionls to vlidly hrterize the fluid-eletrolyte sttus of thletes nd therey suggest modifitions of diet nd trining hits. Without these tehniques, professionls must resort to inurte or indiret estimtes of whole-ody fluid nd eletrolyte lne. The uthors re from the Deprtment of Kinesiology, Humn Performne Lortory, University of Connetiut, Storrs, Conn. Originlly sumitted Mrh 2, 2009. Aepted for pulition My 14, 2009. The uthors hve no finnil or proprietry interest in the mterils presented herein. The uthors thnk Mikey O Connor, phrmist, who enourged pulition of this rtile, nd Brendon MDermott nd Ree Lopez, University of Connetiut, who provided vlule insights regrding use of these tehniques y thleti triners. The initil kground informtion underlying this mnusript ws provided in 1983 y Dvid L. Costill, PhD, Humn Performne Lortory, Bll Stte University, Munie, Ind. Address orrespondene to Lwrene E. Armstrong, PhD, FACSM, Unit 1110, EKIN, Storrs, CT 06269-1110; e-mil: lwrene.rmstrong@uonn.edu. doi:10.3928/19425864-20090625-06 The skin of person weighing 70 kg ontins 200 to 300 erine swet glnds per m 2, eh of whih hs length of pproximtely 1.3 mm. 1,2 Ating under the ontrol of the preopti re of the nterior hypothlmus, efferent nerve impulses stimulte the ody s swet glnds to olletively serete etween 0.8 nd 1.5 L of fluid per hour during moderte-intensity workout. 3 Swet tht ppers on the skin ontins over 40 ompounds, inluding key minerl slts suh s sodium nd hloride (extrellulr ions) or potssium nd mgnesium (intrellulr ions). 4 For most thletes, lned western diet provides mple nutrients tht esily offset swet eletrolyte nd wter losses during exerise. However, when trining or ompetition ours in hot environment or involves multiple exerise sessions per dy or when the individul hs very lrge swet rte or swet slt onentrtion, fluid-eletrolyte losses n exeed 24- hour dietry intke. In these extreme situtions, linil signs nd symptoms (eg, skeletl musle rmps, het exhustion) my rise tht prompt thletes to seek medil ssistne. Unfortuntely, even experiened liniins find it diffiult to preisely dignose nd tret these illnesses euse fluid nd eletrolyte ssessment requires urte mesurements of swet rte (volume of swet produed per hour), swet eletrolyte onentrtion (mg per L of swet), urinry output, fluid onsumption, nd dietry nutrient intke (mg of eletrolyte per 24 hours), s well s lultions of the resulting whole-ody lne. In ddition, the dynmi nd omplex nture of ody fluids omplites dignoses, 5 neessitting n individulized pproh to fluid-eletrolyte evlution. 6,7 Therefore, the primry purpose of this rtile is to desrie numerous ftors tht thleti triners must onsider when ssess- Athleti Trining & Sports Helth Cre Vol. 1 No. 4 2009 169

Armstrong & Cs ing the eletrolyte nd wter turnover of thletes who hve n inresed risk of exertionl het illness or fluideletrolyte imlne. Sine the erly oservtions of erine swet glnd funtion during the 1930s, 8 numerous swet olletion methods hve een used, inluding lol smpling methods (ie, filter pper or guze sorption, skin srping, multisite pipette sution, swet glnd nnultion, ruer glove nd rm g olletion) 9 nd the whole-ody rinse tehnique. 10,11 Severl omprisons of lol swet olletions versus the whole-ody rinse tehnique hve een pulished, ut no previous pulition hs desried ompletely the neessry methods nd lultions. 4,10-17 Virtully ll investigtors hve reported tht lol swet smples hve resulted in higher eletrolyte onentrtions thn smples nlyzed vi whole-ody rinse nd were not vlid representtions of the entire skin surfe. Aknowledging the whole-ody rinse s the method of hoie, the seondry purpose of this rtile is to desrie the whole-ody rinse tehnique of swet eletrolyte nlysis nd to provide detils regrding the tehniques tht llow thleti triners to hrterize n thlete s fluid-eletrolyte sttus on ny given dy. To our knowledge, this is the first pulition to delinete these methods in detiled, omposite doument. Evluting Whole-Body Fluid Blne Tle 1 presents the ftors involved in lulting fluid nd eletrolyte lne. Eqution 1 inorportes the gin of fluid from dietry soures (ie, in everges, wter, nd solid food). This is mesured simply y reording the volume (ml or oz) of wter, fluideletrolyte replement everges, te, offee, juie, or soft drinks tht n thlete onsumes per 24 hours. To this volume, the wter ontined in solid food should e dded. However, this is not fesile in most situtions euse preise mesurement requires weighing eh food item, drying it in n oven, weighing the dried food, nd lulting the wter weight y sutrtion ( 1-g weight hnge equls 1 ml of wter). Beuse time, personnel, or filities usully do not llow desition of food, the wter ontent n e estimted s 20% of the volume onsumed s fluid. 18 For exmple, if n thlete onsumes totl of 3 L of fluid per dy, the moisture ontent of solid food is estimted to e 0.6 L (3.0 L30.20 L = 0.6 L). Some elite thletes re exeptionl in this regrd, s the wter ontent of their solid food hs een reported to e 37% of totl dietry wter. 19 Eqution 1 in Tle 1 lso ontins 3 quntities tht re diffiult to mesure, nd therefore usully re lulted metoli-wter prodution, trnsutneous wter loss, nd respirtory wter loss. Metoli wter is produed when the ody digests nd onverts food to hemil energy, s some iohemil retions generte wter within ells during the proessing of rohydrte, ft, nd protein. The ellulr oxidtion of rohydrte, ft, nd protein yields 0.6 ml, 1.1 ml, nd 0.4 ml of wter per grm, respetively. 20 This lultion requires n thleti triner or dietitin to nlyze the diet for the totl grms of rohydrte, ft, nd protein onsumed. Trnsutneous (ie, ross the skin) nd respirtory losses our ontinuously throughout life s wter loss through the skin nd lungs, respetively. Fortuntely, in most environments nd thleti situtions, the volume of metoli wter produed (ie, pproximtely 500 to 800 ml/dy) 20 is similr to the sum of the trnsutneous plus respirtory wter losses. 21 Thus, the gin nd loss of wter vi these proesses pproximtely nel eh other nd we reommend using the simplified eqution 2; this elimintes the need to mesure metoli, trnsutneous, nd respirtory wter losses. Eqution 3 (Tle 1) is field expedient method tht requires only 2 ody weight mesurements (1 kg = 1 L). Urine exretion, metoli wter prodution, trnsutneous wter loss, nd respirtory wter loss re disregrded. Other inherent ssumptions nd soures of error hve een delineted y Mughn et l. 22 As with equtions 1 nd 2, voiding wter ingestion during the oservtion period simplifies this tehnique nd the ssoited lultions. For equtions 1 nd 2 (Tle 1), swet volume is determined y mesuring ody weight hnge during exerise. The simplest method involves voiding the owel nd ldder, weighing the thlete nude (or while wering undergrments) on digitl floor sle with preision of 0.1 kg (ie, 0.2 l), nd then simulting the onditions of trining or ompetition y exerising for 1 hour nd weighing the thlete nude gin. The swet rte equls the ody weight differene expressed per 1 hour. If fluid is onsumed or if urine is exreted etween the ody weight mesurements, the finl swet rte should e orreted s: swet rte (L per hour) = ody weight differene (1 kg = 1 L)1wter intke (L)2urine volume (L). All ftors re 170 tsh.om

Evluting Eletrolyte nd Wter Turnover Eqution 1 T l e 1 Fluid Eletrolyte Equtions Tht My Be Applied to 24-Hour Period or to Single Exerise Session Fluid lne (ml) = (dietry fluid intke1metoli wter prodution)2(swet volume1urine volume1trnsutneous wter loss1respirtory wter loss) Dietry fluid intke = wter1fluid in everges1fluid in solid foods Eqution 2 Simplified fluid lne (ml) = (dietry fluid intke)2(swet volume1urine volume) Eqution 3 Field expedient fluid lne (ml or L) = (ody weight efore)2(ody weight fter) Eqution 4 Eletrolyte lne (meq or mg) = (dietry intke)2(ontent of urine1fees1swet) In thletes, fel wter nd eletrolyte losses re smll nd diffiult to mesure; therefore, they re not inluded here. 1 kg ody weight = 1 L fluid; 1 g ody weight = 1 ml fluid Content (totl mg or totl meq) = fluid volume (L)3fluid onentrtion (mg/l or meq/l) mesured over 1-hour or hlf-hour period; the ltter is orreted to 1 hour mthemtilly. Assessing Whole-Body Eletrolyte Blne Eqution 4 in Tle 1 onsiders the gin nd loss of eletrolytes (ie, minerl turnover, slt lne) tht onstitutes whole-ody lne. Dietry eletrolyte intke is usully nlyzed on the sis of 24-hour period, ut shorter durtions my e used (eg, prolonged ompetition or doule workout session). Although this eqution my e pplied to sodium, hloride, potssium, mgnesium, or ny other nutrient, the following prgrphs fous primrily on sodium. An individulized pproh to nlysis of fluideletrolyte lne 6,7 requires omputer, softwre, omplete nd urte reord of ll food nd fluid onsumed y the thlete, nd n experiened softwre user. Numerous dietry nlysis softwre pkges re ommerilly ville. Prestwood 23 hs outlined the fetures tht should e onsidered when purhsing dietry softwre progrms. In ddition, the U.S. Deprtment of Agriulture offers free dietry nlysis progrms nd dvie through their We sites (http://www.nutrition.gov nd http://www.nl.usd.gov/fni/foodomp/serh/). This type of nlytil softwre progrm ontins thousnds of food items nd provides informtion to use the tehniques desried elow. One ll food nd fluid items hve een entered into the omputer progrm, it provides numerous outputs inluding totl kilolories; grms of rohydrte, sugrs, ft, protein, mino ids; nd milligrms of sodium, potssium, hloride, mgnesium, nd other minerls. We reommend tht thletes e trined to reord rnd nmes, food quntities (eg, 8 oz, 3 slies, 2 tlespoons), methods of preprtion (eg, fried, ked, tosted, in oil, in wter), the resturnt or dining fility, nd portion size (eg, smll, lrge). Tle 2 presents smple food rell sheet tht thletes my use to reord the food nd fluids they onsume during predetermined 24-hour period. Eqution 4 in Tle 1 involves sodium or other eletrolyte losses in urine, fees, nd swet. All of these mesurements require eletrolyte nlyzers, whih re ommonly used in hospitl lortories or linis. Suh nlyzers use ion-seletive eletrodes tht re sed on thin films or memrnes; the eletrolyte ontent of smple is ompred with referene eletrode. 24 The ontent of sodium (milliequivlents [meq]) in urine is lulted y multiplying the onentrtion (meq/l) y the volume (L); the onentrtion is determined with lortory eletrolyte nlyzer, nd volume is mesured y weighing 24-hour urine olletion on sle or lne (1 g = 1 ml; 1 kg = 1 L). This olletion represents ll urine produed during the 24-hour oservtion period. The eletrolyte nlyzer provides onentrtion in meq; to onvert this unit to mg, multiply meq of sodium y 22.99 or multiply meq of potssium y 39.1. As noted ove, virtully ll pulished omprisons indite tht lol swet olletion methods do not urtely represent the entire ody surfe, nd tht the whole-ody rinse tehnique is the preferred method. 4,10- Athleti Trining & Sports Helth Cre Vol. 1 No. 4 2009 171

Armstrong & Cs T l e 2 Diet Reord Instrutions, Plese reord ll foods, wter, everges, nd supplements tht you onsume during 24-hour period. Helpful Hints Be very speifi in your desription of the type, the preprtion method, nd the mount of eh food nd everge you onsume. Use the lel on foods to help you determine portion sizes. Sve lels from pkges nd return them with your food reord forms (this will gretly ssist nd enhne our nlysis of your true nutrient intke). Use nutrient desriptors (eg, low-ft, ft-free, light, redued lorie) nd rnd nmes to delinete foods. Reord food nd everge onsumption fter eh mel or snk insted of witing until the end of the dy. Dte: Nme: Time Food nd Beverge Desription Amount Totl KCl These food nd fluid items re evluted with ommeril nutritionl nlysis softwre. Free dietry nlysis progrms nd dvie my e found t http://www.nutrition.gov nd http://www.nl.usd.gov/fni/foodomp/serh/. This n e found on the lel. T l e 3 Supplies Required to Perform One Swet Eletrolyte Anlysis Using the Whole-Body Rinse Tehnique Items 1 pir of exerise shorts, soks, nd snekers 1 t-shirt 1 exerise mhine (ie, tredmill, elliptil triner, stir limer, sttionry ike) 2 pirs of nitrile or ltex exmintion gloves 1 eletrolyte-free plsti sheet, 2 plsti jugs (1-gllon pity) filled with distilled wter 2 len towels 3 disposle pipettes (2-mL to 5-mL pity) 6 len plsti test tues with lid or storge p (minimum 0.5-mL pity) 1 digitl floor sle, 0.2 l (ie, 0.1 kg) preision 1 lortory eletrolyte nlyzer 1 stop wth 1 lortory enh top pn lne, 0.01-g to 1.0-g resolution 1 metl wsh tu (1-m dimeter; 15-m to 30-m height) 1 plsti trsh g 1 permnent mrker 1 pir sissors 1 dt sheet (Tle 5) Item is initilly eletrolyte free. Exerise equipment is not neessry if the thlete runs outdoors. A disposle plsti pint trp (0.2-mm to 0.4-mm thikness; 12312 ft) serves this purpose well. 17 The tehnique s proedures require oth sophistited lortory instruments nd simple household items (Tle 3). If eletrolyte nlyzers nd sensitive lnes re not ville, the thleti triner should ontt hospitl or university lortory. Tle 4 presents the proedures tht thleti triners nd investigtors n use to evlute swet eletrolyte onentrtions nd the totl eletrolyte loss during exerise. Severl hours efore exerise, the thleti triner psses the thlete s shorts, soks, nd underwer through one full yle of n utomti wsher, using plin wter nd no sop or detergent; this removes the eletrolytes tht were present in the fiers of the lothing. Clothing items re then dried in n utomti lothes dryer, without softening gents or other speil re. Two th towels should e lened onurrently; these will e used during exerise to lot swet droplets tht form on the skin, efore they fll to the floor. Immeditely prior to exerise, the thlete should tke 5-minute shower without sop (whih my ontin potssium), vigorously sruing ll hir-overed res of the ody with oth hnds. In our experiene, these proedures ensure tht the thlete egins exerise with eletrolytefree lothing nd skin. During exerise, the thleti triner wers nitrile or ltex exmintion gloves, stnds ehind the thlete, nd periodilly lots the thlete s k with towel to pture eletrolytes tht otherwise might drip onto the floor; the thlete does the sme for the front of the ody. Exerise intensity should e strenuous (ie, 70% 172 tsh.om

Evluting Eletrolyte nd Wter Turnover Proedure Collet nd orgnize supplies. T l e 4 Proedures to Evlute Swet Eletrolyte Conentrtion (meq/l) nd Content (totl meq or mg) vi the Whole-Body Rinse Tehnique Lunder ll lothing nd 2 towels, without detergent, in n utomti wsher to remove eletrolytes. Run len lothing through 1 extr rinse yle with wter only. If jugs of ommeril distilled wter re not ville from supermrket, the thleti triner should prepre two 1-gllon plsti milk ontiners y wshing with sopy wter nd rinsing.10 times to remove ll sop residue. Weigh the empty, dry jugs on sensitive pn sle to the nerest 1 g to determine the len jug weight; fill the len plsti jugs with distilled wter (prepred in distilled wter pprtus) nd weigh the jugs gin to the nerest 1 g; the volume of the wter in L is equl to the numer of kg of wter in eh jug (eg, 3.92 kg = 3.92 L). Reord the volume of wter on the dt sheet. Weigh lothing to the nerest 1 g efore exerise. Void owel nd ldder. Shower entire ody with wter. Use no sop or shmpoo. Thoroughly sru ll hiry res. Dress in eletrolyte-free shorts, soks, nd undergrments. Shoes re not rinsed nd need not e lened. Mesure thlete s ody weight to the nerest 0.2 l or 0.1 kg efore exerise. Exerise for 30 or 60 minutes in wrm or hot environment. Men wer no shirts nd women wer sports rs. Blot the skin frequently with len towel to pture swet tht might drip onto the floor. This is more effetive during sttionry yling thn tredmill running. The towel eventully will e dded to the rinse wter. Athlete drinks nothing. Athlete Mesure ody weight to the nerest 0.2 l or 0.1 kg fter exerise. Athlete disroes privtely nd ples shorts nd soks in len, eletrolyte-free plsti g. In the loker room shower re, ple irulr wsh tu (pproximtely 2-m dimeter, 15-m to 30-m wll height) ner floor drins nd line the tu with new eletrolyte-free plsti trp. Edges of the trp should extend well eyond the lip of the tu. Do not soil the trp on the side tht fes the eiling. Wering only underlothing, the thlete steps into the tu nd squts in posture resemling rouhed sell ther. Assistnts, wering gloves, hold the trp vertilly, enirling the thlete in the shpe of plsti ylinder. The gol is to th ll wter (pproximtely 2 gllons or 8 L) tht rinses the ody. While wering plsti gloves, the thleti triner pours distilled wter slowly on ll skin surfes, espeilly on the hir, shoulders, hed, hest, k, rmpit, nd groin res. Athlete srus hiry res s the rinse wter is pplied. During the rinse, the thleti triner egins t the hed nd pours onservtive mount of distilled wter on the slp, stopping periodilly to llow the thlete to sru the hir. Most wter is pplied to hir-overed res of the ody nd skin res tht produe the most swet (eg, hed, shoulders, hest, k, rmpits). Eh zone of the skin surfe should e rinsed twie per gllon jug (pproximtely 3.9 L). The thlete exits the trp nd tu, while the thleti triner ensures tht ll rinse wter remins in the trp. Weigh lothing to the nerest 1 g fter exerise. Sutrt pre-exerise lothing weight to determine the mount of swet tht ws trpped in lothing. While wering gloves, the thleti triner dds ll lothing nd towels to the rinse wter (pproximtely 2 gllons, 8 L). All items re sturted with the rinse wter, mixed thoroughly, nd wrung y hnd severl times. The rinse wter now ontins ll eletrolytes lost in swet during exerise. The thleti triner ollets smple (1 ml to 2 ml) of the rinse wter with len pipette nd trnsfers this smple to len test tue nd sels the tue. The rinse wter inside the test tue is nlyzed for sodium nd potssium onentrtion with lortory eletrolyte nlyzer. The thleti triner lultes sodium lost during exerise (Tle 5), expressed s totl meq/hour or mg/hour. The dietitin or thleti triner reommends speifi food items to reple sodium nd potssium losses. Athleti Triner Although sodium is used s n exmple, this tehnique is vlid for ll nutrients in swet. A new polyethylene indoor pint trp (0.2 mm to 0.4 mm) serves this purpose well. Multiple onseutive rinses hve indited tht single rinse (using 2 gllons or 8 L of distilled wter) ptures 96% to 98% of ll eletrolytes sereted y swet glnds. This is identil to other pulished dt. 10,14 Athleti Trining & Sports Helth Cre Vol. 1 No. 4 2009 173

Armstrong & Cs T l e 5 Smple Whole-Body Rinse Dt Worksheet for 30-Minute Exerise Session Events nd Clultions Pre-Exerise Post-Exerise Differene 1. Clok rel time 8:15 AM 8:45 AM 0.5 hours 2. Athlete ody weight (kg), semi-nude 70 68.9 1.1 3. Weight (kg) of lothing worn during weighing 0.88 0.98 0.1 4. Atul swet volume (L) in 30 minutes 1.2 5. Clulted swet rte (L/hour) 2.4 6. Plsti jug A weight (kg) when empty 0.50 7. Plsti jug B weight (kg) when empty 0.51 8. Distilled wter weight in jug A (kg) 3.94 9. Distilled wter weight in jug B (kg) 3.96 10. Totl rinse wter volume (L) in jug A1jug B 7.90 11. Sodium onentrtion (mg/l rinse wter) 147 d 12. Potssium onentrtion (mg/l rinse wter) 18.8 d 13. Totl sodium (mg) in 7.9 L of rinse wter e 1162 f 14. Totl potssium (mg) in 7.9 L of rinse wter e 148 f 15. Swet sodium onentrtion (mg/l swet) 968 g 16. Swet potssium onentrtion (mg/l swet) 123 g 17. Totl sodium lost (mg) in swet e 1162 h 18. Totl potssium lost (mg) in swet e 148 h Some swet is sored nd trpped in lothing. This is the sum of item 2 nd item 3 in olumn 4. The mesurement is the result of item 44item 1 differene. d The lortory eletrolyte nlyzer provides onentrtion in meq; to onvert to mg, multiply meq sodium y 22.99 or multiply meq potssium y 39.1. e Assuming tht ll swet eletrolytes re ptured in the rinse wter, towels, nd lothing, items 13 nd 17 or items 14 nd 18 re identil. f The mesurement is the result of item 103item 11 or item 103item 12. g The mesurement is the result of item 134item 4 or item 144item 4. h The mesurement is the result of item 153item 4 or item 163item 4. mximl eroi power or simultion of ompetitive event) for 30 or 60 minutes to enourge ner-mximl swet prodution; idelly, ir temperture is wrm (30 C to 34 C) or hot (35 C to 38 C). After exerise, the thleti triner lots the entire skin surfe with towel nd the thlete moves to the shower room for the rinse proedure. If jugs of ommeril distilled wter re not esily otined, the thleti triner should len two plsti milk ontiners, s desried in Tle 4. In either event, the volume of distilled wter in the jugs n e determined urtely y sutrting the weight (g) of the empty jugs from the weight of the jugs whih re filled with distilled wter. Tle 5 presents the mesurements nd lultions tht re required to determine swet eletrolyte losses during 30 minutes of exerise. Although sodium (N1) is the only eletrolyte mentioned, these lultions lso pply to potssium. Row 3 llows the thleti triner to lulte the mount of swet (1.0 g = 1.0 ml; 1.0 kg = 1.0 L) tht is trpped in the lothing of the thlete. To void ontmintion ler sheet of ommerilly ville sndwih wrp is pled on the sle efore lothing items re dded. Rows 4 nd 5 llow totl swet volume (L) nd swet rte (L/hour) to e lulted sed on ody weight differene. If the durtion of exerise ws not 60 minutes, the swet rte in row 5 should e expressed per hour. Row 10 provides the totl volume (L in 2 plsti jugs) of distilled wter tht ws poured over the skin surfe. Row 11 shows the sodium onentrtion (mg/l) of the rinse wter, s determined y lortory eletrolyte nlyzer. Distilled wter n e purhsed t most supermrkets. Row 13 presents the vlue for the totl mount of sodium (mg) in the rinse wter; whih is lulted y multiplying the sodium onentrtion of the rinse wter (mg/l) (row 11) y the volume of wter used to rinse the ody (L) (row 10). Row 17 presents the totl sodium (mg) (1 meq N1 = 22.99 mg N1) lost in swet during exerise; this s- 174 tsh.om

Evluting Eletrolyte nd Wter Turnover T l e 6 Smple Summry Report of Femle Collegite Bsketll Plyer Prepred for Sports Mediine Physiins, Cohes, nd Athletes Athlete Nme Dte Item Mesurement 1. On-ourt prtie time 2.75 hours 2. Wter intke (2.75 hours) 1.94 L 3. Urine volume 0 L 4. Chnge of ody weight 0.81 kg d (21% ody weight) 5. Totl swet volume (2.75 hours) e 3.19 L 6. Swet rte 1.16 L/hour 7. Swet sodium onentrtion f 966 mg/l 8. Totl swet sodium loss 3082 mg 9. Swet potssium onentrtion f 66.5 mg/l 10. Totl swet potssium loss 212 mg 11. 24-hour urine volume 1.3 L 12. Urine sodium onentrtion f 1012 mg/l 13. Totl urine sodium loss 1315 mg 14. Urine potssium onentrtion f 704 mg/l 15. Totl urine potssium loss 915 mg 16. Totl swet1urine sodium loss 4397 mg/dy 17. Totl swet1urine potssium loss 1127 mg/dy 18. 24-hour dietry intke of sodium (3-dy verge) 3622 mg sodium/dy 19. 24-hour dietry intke of potssium (3-dy verge) 1228 mg potssium/dy 20. 24-hour whole-ody sodium lne g 2775 mg/dy 21. 24-hour whole-ody potssium lne g 1101 mg/dy 22. 24-hour swet1urine wter loss 4.49 L The vlues re lulted s desried in Tles 1 nd 5. Wter ottles provided nd weighed y the thleti triner. The mesurement ws the result of preody weight2postody weight. d 1.0 kg = 1.0 L. e Totl swet volume is equl to ody weight loss1wter intke2urine volume. f The lortory eletrolyte nlyzer provides onentrtion in meq; to onvert to mg, multiply meq sodium y 22.99 or multiply meq potssium y 39.1. g Dietry intke2loss vi swet1urine. sumes tht ll sodium on the skin ppered in the rinse wter. Tle 6 depits smple report tht we presented to physiins, ohes, nd thletes. It is different from Tle 5 euse items 2 through 6 were determined during n tul prtie session, y urtely mesuring wter ottles nd ody weight. Items 7 through 10 were evluted in our lortory, using the whole-ody rinse method presented in Tles 4 nd 5. Items 11 through 15 fous on urinry sodium nd potssium losses; wheres items 16 through 17 provide lultions of the omined eletrolyte losses in swet plus urine. Items 18 nd 19 in Tle 6 were determined from reord of 24-hour food nd fluid intke (Tle 2) nd nutritionl nlysis of these food items, using dietry nlysis softwre (desried ove). This report llows the thleti triner to ommunite useful fluid (items 2, 5, 6, nd 11), eletrolyte (items 7 through 10 nd 12 through 17), nd dietry informtion to physiins, ohes, nd thletes. The keys to understnding exertionl illnesses (eg, het exhustion or het rmps) inlude ompring dietry intke to whole-ody loss nd determining the defiit or ompring the mgnitude of dietry intke nd whole-ody loss to pulished dt nd determining Athleti Trining & Sports Helth Cre Vol. 1 No. 4 2009 175

Armstrong & Cs whether either flls outside the referene (ie, expeted) rnge. Referene Vlues To hek the vlidity of dt, thleti triners n ompre their mesurements nd lultions to those pulished y other reserh nd linil tems. For exmple, Rehrer nd Burke 3 ompiled dt from 24 studies tht desried the swet rtes of thletes in vrious sports. Women experiened swet losses rnging from 0.7 or 0.8 L/hour (sketll indoor trining, 25 C, 43% reltive humidity; soer outdoor trining, 9 C, 35% reltive humidity; yling 40 km t 30 km/hour speed, pproximtely 25 C) to 1.5 L/hour (10 km run t 12.8 km/hour speed, pproximtely 21 C). Men enountered higher swet rtes, rnging from 0.7 L/hour (soer trining, 9 C, 61% reltive humidity; yling 40 km t 30 km/hour speed, pproximtely 20 C) to 1.8 L/hour (10 km run t 14.6 km/hour speed, pproximtely 21 C; Austrlin footll, 27 C, 52% reltive humidity) or 2.1 L/hour (soer trining, 33 C, 40% reltive humidity). Lemon et l 14 oserved 6 men during 60 minutes of tredmill running in 23 C lortory environment; they reported swet rtes of 0.46, 0.77, nd 0.92 L/hour t exerise intensities of 42% (low), 55% (moderte), nd 67% (high) of mximl eroi power, respetively. As further point of omprison, Stofn et l 25 reported tht Amerin footll linemen, wering full uniform nd helmet, lost 3.461.5 L of swet during 2.3-hour trining session in mild environment (19 C to 26 C). Similrly, lrge footll linemen in the U.S. Ntionl Footll Legue exhiited swet rte of 2.39 L/hour. 26 Among the highest swet rtes pulished in the literture, femle rower experiened 2.3 L/hour loss during trining, 27 the swet rte of mle tennis plyer ws mesured t 3.4 L/hour, 28 nd tht of n elite distne runner ws 3.7 L/hour. 29 Virtully ll pulitions tht report swet eletrolyte nlyses with the whole-ody rinse tehnique (Tle 5) were onduted in lortories. These studies present the following rnges: swet sodium onentrtion, 8 to 64 meq/l, 30 13 to 47 meq/l, 31 nd 40 to 60 meq/l 32 ; swet hloride onentrtion, 13 to 38 meq/l, 31 30 to 50 meq/ L, 32 nd 32 to 70 meq/l. 10 The rtio of sodium to swet potssium onentrtion, 2 to 5 meq/l, 31 3 to 7 meq/l, 10 nd 4 to 5 meq/l 32 ; swet mgnesium onentrtion, 2 to 5 meq/l, 32 nd 1 to 3 meq/l 10 ; swet lium onentrtion, 4 to 9 meq/l, 32 nd 1 to 6 meq/l. 10 To onvert the unit meq to mg, multiply the numer of meq y the following ftors: sodium, 22.99; hloride, 35.45; potssium, 39.10; mgnesium, 12.16; nd lium, 20.03. Dily urine volume (ml per 24 hours) is different for men nd women, depending on ody size. The rnge for men is 690 to 2690 ml per dy (men = 1360 ml per dy). The rnge for women is 490 to 2260 ml per dy (men = 1130 ml per dy) if they use no hormonl ontreptives, ut 320 to 2290 ml per dy (men = 980 ml per dy) if they use ontreptives. 33 The totl dily loss of eletrolytes in urine (meq per 24 hours) vries gretly, lso depending on dietry intke. The following rnges demonstrte this point: urinry sodium loss, 40 to 220 meq per dy; urinry hloride loss, 169 to 395 meq per dy; urinry potssium loss, 30 to 90 meq per dy; urinry lium loss, 1 to 4 meq per dy; urinry mgnesium loss, 4 to 16 meq per dy. 33,34 To onvert meq to mg, multiply the numer of meq y the ftors presented ove. Urinry eletrolyte onentrtions (meq/l) vry gretly, depending on dietry onsumption nd swet losses. 31 For exmple, men who onsume high eletrolyte diet (399 meq or 9173 mg of sodium per dy, plus 80 meq or 3128 mg of potssium per dy) exhiit these rnges of onentrtion: urine sodium (onfidene intervl [CI], 23-89 meq/l); urine potssium (CI, 36-71 meq/l). 35 In ontrst, men who onsume low sodium diet (98 meq or 2253 mg of sodium per dy, plus 80 meq or 3128 mg of potssium per dy) hve these rnges of onentrtion: urine sodium (CI, 133-263 meq/l); urine potssium (21-62 meq/l). 35 Fel sodium ontent my e nlyzed in lortory ut is usully onsidered to e negligile, ompred with urine nd swet losses, or is estimted s,10 meq per dy (,0.2 g per dy) 33 ; this is lso true for hloride, potssium, mgnesium, nd lium. We reommend one study 35 s soure of typil fluid-eletrolyte rnges nd onise exmple of the tehniques desried in the urrent rtile. This investigtion involved helthy men who performed 90 minutes of exerise in hot environment on onseutive dys. It provides referene vlues for swet rte, swet eletrolyte, urine volume, urinry eletrolyte, 8-dy lultions of whole-ody sodium nd potssium lne, nd musle wter, nd eletrolyte onentrtions. Limittions Two primry limittions exist in the methods disussed. First, dietry reords re only s vlid s the detils pro- 176 tsh.om

Evluting Eletrolyte nd Wter Turnover T l e 7 Eletrolyte Content of Foods Tht Cn Be Consumed to Offset Sodium nd Potssium Losses in Swet nd Urine, Item Sodium (mg) Potssium (mg) Onion soup, dry mix, 1 pket 3132 281 Tle slt, 1 tespoon 2563 0 Sumrine sndwih, fst food, old uts, 6 roll 1651 394 Cheeseurger sndwih, fst food, 1 lrge ptty 1314 460 Sumrine sndwih, fst food, tun, 6 roll 1293 335 Tomto sue, nned, 1 up 1284 811 To, fst food, 1 lrge 1233 729 Bked ens, nned, pork, tomto sue, 1 up 1114 746 Beef stew, nned entree, 1 up 947 404 Fish sndwih, fst food, trtr sue, heese 939 353 Beef noodle soup, nned, dd wter, 1 up 930 98 Cottge heese, low ft, 2% milk, 1 up 918 217 Soy sue mde from soy nd whet, 1 tsp 902 35 Sumrine sndwih, fst food, rost eef, 6 roll 845 330 Sport drink, ommeril, 20 oz 270 75 Potto, fst food, Frenh fried vegetle oil, 1 medium 260 737 Tomto pste, nned, 1 up 257 2657 Vegetle sld, fst food, hiken, no dressing, 1.5 ups 209 447 Potto hips, snk, plin, slted, 1 oz 149 466 Bked potto, with skin, no slt dded, 7 oz 20 1081 Seedless risins, 1 up 16 1086 Tril mix snk, tropil, 1 up 14 993 Frozen ornge juie, 6 fl oz 6 1436 Grpefruit juie, white, frozen onentrte, 6 fl oz 6 1002 Dtes, 1 up 4 1168 Clultion of sodium nd potssium losses re desried in Tle 6. Soure: Ntionl Agriulturl Lirry We site. http://www.nutrition.gov/nl-disply/index.php?info_enter=11&tx_level=1. Updted My 11, 2009. Aessed June 1, 2009. This item is unsweetened nd undiluted. vided y users nd my e inurte when re is not tken. Completeness is essentil. Retining food wrppers, pkges, nd oxes improves the ury of dietry nlysis. Seond, the methods desried in this rtile re not required for the mjority of thletes, ut these methods will e pproprite espeilly when sodium or potssium defiienies result in linil mnifesttions (ie, exerise in hot environment). Clinil Implitions The following se report demonstrtes how the ove methods my e pplied. A 21-yer-old femle ollegite sketll plyer (height = 71 in [180 m]; ody weight = 170 l [77.1 kg]) ws referred to our lortory midseson with 3-yer history of reurring musle rmps. Beuse her signs nd symptoms were similr to those of exertionl het rmps, 36 we expeted tht, lthough ll prties hd een onduted in limte-ontrolled indoor ren, sodium imlne existed. She mintined 24-hour food nd fluid reord for 3 dys (Tle 2) nd prtiipted in whole-ody rinse proedure (Tle 4) tht llowed us to determine her swet sodium nd potssium onentrtions. Mesurements of fluid intke nd ody weight hnge during 2 hour nd 45 minuteindoor prtie session in n ir onditioned environment llowed us to ssess her swet rte nd to prepre report similr to the report in Tle 6. Our omprison of diet versus swet nd urine eletrolyte losses deter- Athleti Trining & Sports Helth Cre Vol. 1 No. 4 2009 177

Armstrong & Cs mined tht she ws t risk for sodium defiieny. This ws ggrvted y her onsumption of moderte level of sodium (3622 mg per dy). Fortuitously, we lso determined from her diet reord tht she ws eting low protein nd hypolori diet, neither of whih likely ffeted her musle rmps ut my hve deresed her physil performne over time. Counseling sessions with sport dietitin resulted in the thlete onsuming more sodium, lories, nd protein eh dy. This pln resolved her prolem with musle rmps (ie, presumly sodiumrelted defiieny), whih did not return during the reminder of tht seson or the entire next seson. This individulized evlution demonstrted the effiy of the methods presented in this rtile nd verified tht sodium imlne n our in mild environment. The se report lso supports previous field nd lortory studies 28,30,31,35,36 tht evluted the slt-wter lne of thletes, soldiers, nd young men. For exmple, Bergeron 28,36 identified whole-ody sodium defiit, inresed dietry sodium onsumption, nd reversed deilitting het rmps. Under extreme environmentl onditions suh s summer tennis tournments or Amerin footll twie-dily workout sessions, loss of 10 L of swet (with swet onentrtion of 50 meq sodium/l) results in loss of 500 meq (11,495 mg) of sodium. Suh sodium loss exeeds the estimted minimum dult requirement of 500 mg sodium nd the usul dily Amerin intke of 1800 to 5000 mg of sodium. 37 This loss lso gretly exeeds the ontents of one 8 oz (240 ml) ottle of fluid-eletrolyte replement everge (110 mg sodium) nd emphsizes the onept tht the thlete s diet must provide neessry wter nd eletrolytes or the risk of exertionl het exhustion nd het rmps will inrese. Thus, s long s ompetitive sports exist, it is inevitle tht eletrolyte defiienies will our in some thletes even if they onsume sport drinks. How n n thleti triner mke informed deisions regrding reognition nd nutritionl interventions? One pproh involves reommending speifi food items tht re high in sodium nd potssium. Thus, Tle 7 presents the eletrolyte ontent of vrious food items tht n e ompred with the 24- hour whole-ody sodium lne nd potssium lne in Tle 5 (items 20 nd 21). Conlusion The methods desried in this rtile llow motivted professionls to perform mesurements of wter nd minerl turnover, reltive to dietry intke, nd to hrterize n thlete s fluid-eletrolyte sttus on ny given dy. These tehniques re most importnt when swet losses of speifi nutrient (eg, sodium) re lrge (ie, during exerise in hot environments), dietry intke of tht nutrient is smll, or when the risk of exertionl het illness is gret. Not only n these methods ssist the design of individulized nutritionl plns for eh thlete, they lso llow orretion of nutrient imlnes tht ordinrily might go unexplined or unreognized. Evidene for these pplitions ppers in previous studies 4,10-17,30,31 s well s in this study s se report. In ddition, we elieve tht other pprohes (eg, estimtion tehniques, popultion norml vlues, lol swet olletions) fil to hrterize fluid-eletrolyte turnover urtely. The strength of this rtile lies in the individulized pproh to determining fluid nd eletrolyte lne euse individul diets, swet rtes, nd swet nd urine ontents vry mong thletes nd re ffeted y environmentl onditions, diet, nd exerise intensity. Thus, n individulized nlysis provides the most effetive pproh to repling fluid nd eletrolyte losses. 6,7 n Referenes 1. Kuno Y. Humn Perspirtion. Springfield, IL: Chrles C. Thoms; 1956. 2. Sto K. Swet indution from n isolted erine swet glnd. Am J Physiol. 1973;225:1147-1152. 3. Rehrer NJ, Burke LM. Swet losses during vrious sports. Austrlin Journl of Nutrition nd Dietetis. 1996;53(suppl 4):S13-S16. 4. Roinson S, Roinson AH. Chemil omposition of swet. Physiol Rev. 1954;34:202-220. 5. Armstrong LE. Assessing hydrtion sttus: The elusive gold stndrd. J Am Coll Nutr. 2007;26(5 suppl):575s-584s. 6. Cs DJ, Armstrong LE, Hillmn SK, et l. Ntionl Athleti Triners Assoition position sttement: Fluid replement for thletes. J Athl Trin. 2000;35:212-224. 7. Cs DJ. Proper hydrtion for distne running identifying individul fluid needs. Trk Coh. 2004;167:5321-5328. 8. Kuno Y. Vritions in seretory tivity of humn swet glnds. Lnet. 1938;1:299-303. 9. Montin SJ, Cheuvront SN, Lukski HC. Swet minerl-element responses during 7 h of exerise-het stress. Int J Sport Nutr Exer Met. 2007;17:574-582. 10. Shirreffs SM, Mughn RJ. Whole ody swet olletion in humns: An improved method with preliminry dt on eletrolyte ontent. J Appl Physiol. 1997;82:336-341. 11. Vellr OD. Studies on swet losses of nutrients. I: Iron ontent of whole ody swet nd its ssoition with other swet onstituents, serum iron levels, hemtologil indies, ody surfe re, nd swet rte. Snd J Clin L Invest. 1968;21:157-167. 178 tsh.om

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