Abstract
Purpose
To determine the impact of altering dietary sodium intake for 3 days preceding exercise on sweat sodium concentration [Na+], and cardiovascular and thermoregulatory variables.
Methods
Fifteen male endurance athletes (runners n = 8, cyclists n = 7) consumed a low (LNa, 15 mg kg−1 day−1) or high (HNa, 100 mg kg−1 day−1) sodium diet, or their usual free-living diet [UDiet, 46 (37–56) mg kg−1 day−1] for 3 days in a double-blind, randomized cross-over design, collecting excreted urine (UNa) and refraining from exercise. On day 4, they completed 2 h running at 55% \(\dot{V}\)O2max or cycling at 55% maximum aerobic power in Tamb 35 °C. Pre- and post-exercise blood samples were collected, and sweat from five sites using absorbent patches along the exercise protocol.
Results
UNa on days 2–3 pre-exercise [mean (95% CI) LNa 16 (12–19) mg kg−1 day−1, UDiet 46 (37–56) mg kg−1 day−1, HNa 79 (72–85) mg kg−1 day−1; p < 0.001] and pre-exercise aldosterone [LNa 240 (193–286) mg kg−1 day−1, UDiet 170 (116–224) mg kg−1 day−1, HNa 141 (111–171) mg kg−1 day−1; p = 0.001] reflected sodium intake as expected. Pre-exercise total body water was greater following HNa compared to LNa (p < 0.05), but not UDiet. Estimated whole-body sweat [Na+] following UDiet was 10–11% higher than LNa and 10–12% lower than HNa (p < 0.001), and correlated with pre-exercise aldosterone (1st h r = − 0.568, 2nd h r = − 0.675; p < 0.01). Rectal temperature rose more quickly in LNa vs HNa (40–70 min; p < 0.05), but was similar at the conclusion of exercise, and no significant differences in heart rate or perceived exertion were observed.
Conclusions
Three day altered sodium intake influenced urinary sodium excretion and sweat [Na+], and the rise in rectal temperature, but had no effect on perceived exertion during moderate-intensity exercise in hot ambient conditions.
Similar content being viewed by others
Abbreviations
- CHO:
-
Carbohydrate
- CI:
-
Confidence interval
- CV:
-
Coefficient of variation
- FA:
-
Forearm
- FH:
-
Forehead
- GIS:
-
Gastrointestinal symptoms
- Hb:
-
Haemoglobin
- HCT:
-
Haematocrit
- HNa:
-
High sodium diet (100 mg kg−1 day−1)
- HR:
-
Heart rate
- ISE:
-
Ion selective electrode
- LNa:
-
Low sodium diet (15 mg kg−1 day−1)
- LSR:
-
Local sweat rate
- MAP:
-
Maximum aerobic power
- MT:
-
Mid-thigh
- Na+ :
-
Sodium
- [Na+]:
-
Sodium concentration
- NaCl:
-
Sodium chloride
- P Osm :
-
Plasma osmolality
- P v :
-
Plasma volume
- RPE:
-
Rating of perceived exertion
- SD:
-
Standard deviation
- SS:
-
Superior scapula
- T amb :
-
Ambient temperature
- TBW:
-
Total body water
- TCR:
-
Thermal comfort rating
- T re :
-
Rectal temperature
- UC:
-
Upper chest
- UDiet:
-
Usual free-living diet (mean: 46 mg kg−1 day−1)
- UNa:
-
Urinary sodium excretion
- USG:
-
Urine specific gravity
- \(\dot{V}\)O2max :
-
Maximal oxygen uptake
- \(\dot{V}\)O2peak :
-
Peak oxygen uptake
- WB:
-
Whole body
- WBW:
-
Whole body washdown
References
Alcock R, McCubbin A, Camões-Costa V, Costa RJS (2018) Case study: providing nutritional support to an ultraendurance runner in preparation for a self-sufficient multistage ultramarathon: rationed versus full energy provisions. Wilderness Environ Med 29(4):508–520. https://doi.org/10.1016/j.wem.2018.06.004
Armstrong LE, Costill DL, Fink WJ (1985) Effects of dietary sodium on body and muscle potassium content during heat acclimation. Eur J Appl Physiol Occup Physiol 54(4):391–397
Baker LB (2017) Sweating rate and sweat sodium concentration in athletes: a review of methodology and intra/interindividual variability. Sports Med 47(Suppl 1):111–128. https://doi.org/10.1007/s40279-017-0691-5
Baker LB, Barnes KA, Anderson ML, Passe DH, Stofan JR (2016) Normative data for regional sweat sodium concentration and whole-body sweating rate in athletes. J Sports Sci 34(4):358–368. https://doi.org/10.1080/02640414.2015.1055291
Baker LB, De Chavez PJD, Ungaro CT, Sopeña BC, Nuccio RP, Reimel AJ, Barnes KA (2018) Exercise intensity effects on total sweat electrolyte losses and regional vs. whole-body sweat [Na+], [Cl−], and [K+]. Eur J Appl Physiol. https://doi.org/10.1007/s00421-018-4048-z (in press)
Baker LB, Stofan JR, Hamilton AA, Horswill CA (2009) Comparison of regional patch collection vs. whole body washdown for measuring sweat sodium and potassium loss during exercise. J Appl Physiol 107(3):887–895. https://doi.org/10.1152/japplphysiol.00197.2009
Baker LB, Ungaro CT, Barnes KA, Nuccio RP, Reimel AJ, Stofan JR (2014) Validity and reliability of a field technique for sweat Na+ and K+ analysis during exercise in a hot-humid environment. Physiol Rep 2(5):e12007. https://doi.org/10.14814/phy2.12007
Borg GA (1982) Psychophysical bases of perceived exertion. Med Sci Sports Exerc 14(5):377–381
Buono MJ, Claros R, Deboer T, Wong J (2008) Na+ secretion rate increases proportionally more than the Na+ reabsorption rate with increases in sweat rate. J Appl Physiol 105(4):1044–1048. https://doi.org/10.1152/japplphysiol.90503.2008
Castro-Sepulveda M, Cancino J, Fernández-Verdejo R, Pérez-Luco C, Jannas-Vela S, Ramirez-Campillo R, del Coso J, Zbinden-Foncea H (2019) Basal serum cortisol and testosterone/cortisol ratio are related to rate of Na+ lost during exercise in elite soccer players. Int J Sports Nutr Exerc Metab. https://doi.org/10.1123/ijsnem.2019-0129 (in press)
Chinevere TD, Kenefick RW, Cheuvront SN, Lukaski HC, Sawka MN (2008) Effect of heat acclimation on sweat minerals. Med Sci Sports Exerc 40(5):886–891. https://doi.org/10.1249/MSS.0b013e3181641c04
Collins KJ (1966) The action of exogenous aldosterone on the secretion and composition of drug-induced sweat. Clin Sci 30(2):207–221
Conn JW, Arbor A (1963) Aldosteronism in man—some clinical and climatological aspects—Part I. JAMA 183:775–781
Conn JW, Johnston MW, Louis LH (1946) Relationship between salt intake and sweat salt concentration under conditions of hard work in humid heat. Fed Proc 5(1):230
Costa RJ, Oliver SJ, Laing SJ, Waiters R, Bilzon JL, Walsh NP (2009) Influence of timing of postexercise carbohydrate-protein ingestion on selected immune indices. Int J Sport Nutr Exerc Metab 19(4):366–384
Costa RJ, Gill SK, Hankey J, Wright A, Marczak S (2014) Perturbed energy balance and hydration status in ultra-endurance runners during a 24 h ultra-marathon. Br J Nutr 112(3):428–437. https://doi.org/10.1017/S0007114514000907
Currell K, Jeukendrup AE (2008) Superior endurance performance with ingestion of multiple transportable carbohydrates. Med Sci Sports Exerc 40(2):275–281. https://doi.org/10.1249/mss.0b013e31815adf19
Dill DB, Costill DL (1974) Calculation of percentage changes in volumes of blood, plasma, and red cells in dehydration. J Appl Physiol 37(2):247–248
Dziedzic CE, Ross ML, Slater GJ, Burke LM (2014) Variability of measurements of sweat sodium using the regional absorbent-patch method. Int J Sports Physiol Perform 9(5):832–838. https://doi.org/10.1123/ijspp.2013-0480
Earhart EL, Weiss EP, Rahman R, Kelly PV (2015) Effects of oral sodium supplementation on indices of thermoregulation in trained, endurance athletes. J Sports Sci Med 14(1):172–178
Fortney SM, Wenger CB, Bove JR, Nadel ER (1984) Effect of hyperosmolality on control of blood flow and sweating. J Appl Physiol Respir Environ Exerc Physiol 57(6):1688–1695. https://doi.org/10.1152/jappl.1984.57.6.1688
Gaskell SK, Snipe RMJ, Costa RJS (2019) Test re-test reliability of a modified visual analogue scale assessment tool for determining incidence and severity of gastrointestinal symptom in response to exercise stress. Int J Sport Nutr Exerc Metab. https://doi.org/10.1123/ijsnem.2018-0215 (in press)
Gill SK, Allerton DM, Ansley-Robson P, Hemmings K, Cox M, Costa RJ (2016) Does short-term high dose probiotic supplementation containing lactobacillus casei attenuate exertional-heat stress induced endotoxaemia and cytokinaemia? Int J Sport Nutr Exerc Metab 26(3):268–275. https://doi.org/10.1123/ijsnem.2015-0186
Goulet ED, Asselin A (2015) Reliability and validity of a low cost, pocket-sized and battery operated sodium analyzer in measuring urinary sodium concentration. Technol Health Care 23(6):881–891. https://doi.org/10.3233/THC-151028
Hamouti N, Fernandez-Elias VE, Ortega JF, Mora-Rodriguez R (2014) Ingestion of sodium plus water improves cardiovascular function and performance during dehydrating cycling in the heat. Scand J Med Sci Sports 24(3):507–518. https://doi.org/10.1111/sms.12028
Hargreaves M, Morgan T, Snow R, Guerin M (1989) Exercise tolerance in the heat on normal and low sodium diets. Clin Sci 76:553–557
Hawley JA, Noakes T (1992) Peak power output predicts maximal oxygen uptake and performance time in trained cyclists. Eur J Appl Physiol 65(1):79–83
Hoffman MD, Stellingwerff T, Costa RJS (2018) Considerations for ultra-endurance activities: part 2—hydration. Res Sports Med. https://doi.org/10.1080/15438627.2018.1502189
Hollies NRS, Goldman RF (eds) (1977) Psychological scaling in comfort assessment. In: Clothing comfort: interaction of thermal, ventilation, construction, and assessment factors. Science Publishers Inc., Ann Arbor
Holmes N, Bates G, Zhao Y, Sherriff J, Miller V (2016) The effect of exercise intensity on sweat rate and sweat sodium and potassium losses in trained endurance athletes. Ann Sports Med Res 3(2):1063–1066
Hooper L, Abdelhamid A, Ali A, Bunn DK, Jennings A, John WG, Kerry S, Lindner G, Pfortmueller CA, Sjöstrand F, Walsh NP, Fairweather-Tait SJ, Potter JF, Hunter PR, Sheepstone L (2015) Diagnostic accuracy of calculated serum osmolarity to predict dehydration in older people: adding value to pathology laboratory reports. BMJ Open 5:e008846. https://doi.org/10.1136/bmjopen-2015-008846
Kennedy NSJ, Eastell R, Smith MA, Tothill P (1983) Normal levels of total body sodium and chlorine by neutron activation analysis. Phys Med Biol 28(3):215–221
Koenders EE, Franken CPG, Cotter JD, Thornton SN, Rehrer NJ (2017) Restricting dietary sodium reduces plasma sodium response to exercise in the heat. Scand J Med Sci Sports 27(11):1213–1220. https://doi.org/10.1111/sms.12748
Konikoff F, Shoenfeld Y, Magazanik A (1986) Effects of salt loading during exercise in a hot dry climate. Biomed Pharmacother 40(8):296–300
Land MA, Neal BC, Johnson C, Nowson CA, Margerison C, Petersen KS (2018) Salt consumption by Australian adults: a systematic review and meta-analysis. Med J Aust 208(2):75–81. https://doi.org/10.5694/mja17.00394
McCance RA (1938) The effect of salt deficiency in man on the volume of the extracellular fluids, and on the composition of sweat, saliva, gastric juice and cerebrospinal fluid. J Physiol 92:208–218
McCubbin AJ, Costa RJS (2018) The impact of dietary sodium intake on sweat sodium concentration in response to endurance exercise: a systematic review. Int J Sports Sci 8(1):25–37. https://doi.org/10.5923/j.sports.20180803.05
McCubbin AJ, Cox GR, Costa RJS (2019) Sodium intake beliefs, information sources and intended practices of endurance athletes before and during exercise. Int J Sport Nutr Exerc Metab. https://doi.org/10.1123/ijsnem.2018-0270 (in press)
Morgan R, Patterson M, Nimmo M (2004) Acute effects of dehydration on sweat composition in men during prolonged exercise in the heat. Acta Physiol Scand 182(1):37–43. https://doi.org/10.1111/j.1365-201X.2004.01305.x
Olsson K, Saltin B (1970) Variation in total body water with muscle glycogen changes in man. Acta Physiol Scand 80(1):11–18. https://doi.org/10.1111/j.1748-1716.1970.tb04764.x
Rakova N, Kitada K, Lerchl K, Dahlmann A, Birukov A, Daub S, Kopp C, Pedchenko T, Zhang Y, Beck L, Johannes B, Marton A, Müller DN, Rauh M, Luft FC, Titze J (2017) Increased salt consumption induces body water conservation and decreases fluid intake. J Clin Invest 127(5):1932–1943. https://doi.org/10.1172/JCI88530
Racinais S, Moussay S, Nichols D, Travers G, Belfekih T, Schumacher YO, Periard JD (2019) Core temperature up to 41.5 °C during the UCI road cycling world championships in the heat. Br J Sports Med 53(7):426–429. https://doi.org/10.1136/bjsports-2018-099881
Ramanathan NL, Sen Gupta A, Lundgren NP (1956) Changes in the salt concentration of sweat during exercise in monsoon weather. Indian J Med Res 44(2):377–384
Robinson S, Kincaid RK, Rhamy RK (1950) Effect of salt deficiency on the salt concentration in sweat. J Appl Physiol 3(2):55–62
Robinson SN, Nicholas JR, Smith JH, Daly WJ, Pearcy M (1955) Time relation of renal and sweat gland adjustments to salt deficiency in men. J Appl Physiol 8(2):159–165
Sato K (1977) The physiology, pharmacology, and biochemistry of the eccrine sweat gland. Rev Physiol Biochem Pharmacol 79:51–131
Sato K, Dobson RL (1970) Regional and individual variations in the function of the human eccrine sweat gland. J Invest Dermatol 54(6):443–449. https://doi.org/10.1111/1523-1747.ep12259272
Sato K, Kang WH, Saga K, Sato KT (1989) Biology of sweat glands and their disorders. I. Normal sweat gland function. J Am Acad Dermatol 20(4):537–563
Saunders AG, Dugas JP, Tucker R, Lambert MI, Noakes TD (2005) The effects of different air velocities on heat storage and body temperature in humans cycling in a hot, humid environment. Acta Physiol Scand 183:241–255
Sawka MN, Young AJ, Francesconi RP, Muza SR, Pandolf KB (1985) Thermoregulatory and blood responses during exercise at graded hypohydration levels. J Appl Physiol 59(5):1394–1401. https://doi.org/10.1152/jappl.1985.59.5.1394
Sawka MN, Burke LM, Eichner ER, Maughan RJ, Montain SJ, Stachenfeld NS (2007) American College of Sports Medicine position stand. Exercise and fluid replacement. Med Sci Sports Exerc 39(2):377–390. https://doi.org/10.1249/mss.0b013e31802ca597
Shirreffs SM, Maughan RJ (1997) Whole body sweat collection in humans: an improved method with preliminary data on electrolyte content. J Appl Physiol 82(1):336–341
Shirreffs SM, Sawka MN (2011) Fluid and electrolyte needs for training, competition, and recovery. J Sports Sci 29(Suppl 1):S39–S46. https://doi.org/10.1080/02640414.2011.614269
Sims ST, Rehrer NJ, Bell ML, Cotter JD (2007a) Preexercise sodium loading aids fluid balance and endurance for women exercising in the heat. J Appl Physiol (1985) 103(2):534–541. https://doi.org/10.1152/japplphysiol.01203.2006
Sims ST, van Vliet L, Cotter JD, Rehrer NJ (2007b) Sodium loading aids fluid balance and reduces physiological strain of trained men exercising in the heat. Med Sci Sports Exerc 39(1):123–130. https://doi.org/10.1249/01.mss.0000241639.97972.4a
Smith CJ, Havenith G (2011) Body mapping of sweating patterns in male athletes in mild exercise-induced hyperthermia. Eur J Appl Physiol 111(7):1391–1404. https://doi.org/10.1007/s00421-010-1744-8
Snipe RMJ, Khoo A, Kitic CM, Gibson PR, Costa RJS (2017) Carbohydrate and protein intake during exertional heat stress ameliorates intestinal epithelial injury and small intestine permeability. Appl Physiol Nutr Metab 42(12):1283–1292. https://doi.org/10.1139/apnm-2017-0361
Snipe RMJ, Khoo A, Kitic CM, Gibson PR, Costa RJS (2018a) The impact of mild heat stress during prolonged running on gastrointestinal integrity, gastrointestinal symptoms, systemic endotoxin and cytokine profiles. Int J Sports Med. https://doi.org/10.1055/s-0043-122742 (in press)
Snipe RMJ, Khoo A, Kitic CM, Gibson PR, Costa RJS (2018b) The impact of exertional-heat stress on gastrointestinal integrity, gastrointestinal symptoms, systemic endotoxin and cytokine profile. Eur J Appl Physiol 118(2):389–400. https://doi.org/10.1007/s00421-017-3781-z
Takamata A, Mack GW, Gillen CM, Jozsi AC, Nadel ER (1995) Osmoregulatory modulation of thermal sweating in humans: reflex effects of drinking. Am J Physiol Regul Integr Comp Physiol 268(2):R414–R422. https://doi.org/10.1152/ajpregu.1995.268.2.R414
Takamata A, Yoshida T, Nishida N, Morimoto T (2001) Relationship of osmotic inhibition in thermoregulatory responses and sweat sodium concentration in humans. Am J Physiol Regul Integr Comp Physiol 280(3):R623–R629. https://doi.org/10.1152/ajpregu.2001.280.3.R623
Taylor NAS, Tipton MJ, Kenny GP (2014) Considerations for the measurement of core, skin and mean body temperatures. J Therm Biol 46:72–101. https://doi.org/10.1016/j.jtherbio.2014.10.006
Thomas DT, Erdman KA, Burke LM (2016) American College of Sports Medicine joint position statement. Nutrition and athletic performance. Med Sci Sports Exerc 48(3):543–568. https://doi.org/10.1249/mss.0000000000000852
Trangmar SJ, González-Alonso J (2017) New insights into the impact of dehydration on blood flow and metabolism during exercise. Exerc Sport Sci Rev 45(3):146–153. https://doi.org/10.1249/JES.0000000000000109
Watson PE, Watson ID, Batt RD (1980) Total body water volumes for adult males and females estimated from simple anthropometric measurements. Am J Clin Nutr 33(1):27–39
Yamazaki F, Fujii N, Sone R, Ikegami H (1994) Mechanisms of potentiation in sweating induced by long-term physical training. Eur J Appl Physiol 69:228–232
Yoshida T, Shin-ya H, Nakai S, Yorimoto A, Morimoto T, Suyama T, Sakurai M (2006) Genomic and non-genomic effects of aldosterone on the individual variation of the sweat Na+ concentration during exercise in trained athletes. Eur J Appl Physiol 98(5):466–471. https://doi.org/10.1007/s00421-006-0295-5
Zadow EK, Kitic CM, Wu SS, Smith ST, Fell JW (2016) Validity of power settings of the Wahoo KICKR power trainer. Int J Sports Physiol Perform 11(8):1115–1117. https://doi.org/10.1123/ijspp.2015-0733
Acknowledgements
The authors would like to thank the participants for their significant time commitment in completing this study, as well as Alexandra Stone, Alice Mika, Ashleigh Gale, Camilo Cayazaya, Rebecca Sue, and Holly Bolton for their assistance in the laboratory during data collection.
Funding
Funding for this work was provided by the Monash University, Be Active, Sleep Eat (BASE) Strategic Grants Scheme, and an Australian Government Research Training Program (RTP) Scholarship.
Author information
Authors and Affiliations
Contributions
AM, GC, JC, and RC were involved in the study design. AM recruited participants. AM and ML collected the data. AM, ML, and RC analyzed all samples. AM and ML analyzed all data. Data interpretation and manuscript preparation were undertaken by AM, JC, GC, and RC. All authors approved the final version of the paper.
Corresponding author
Ethics declarations
Conflict of interest
The authors have no conflicts of interest, financial or otherwise, to declare.
Additional information
Communicated by George Havenith.
Publisher's Note
Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.
Rights and permissions
About this article
Cite this article
McCubbin, A.J., Lopez, M.B., Cox, G.R. et al. Impact of 3-day high and low dietary sodium intake on sodium status in response to exertional-heat stress: a double-blind randomized control trial. Eur J Appl Physiol 119, 2105–2118 (2019). https://doi.org/10.1007/s00421-019-04199-2
Received:
Accepted:
Published:
Issue Date:
DOI: https://doi.org/10.1007/s00421-019-04199-2