Effect of sauna-based heat acclimation on plasma volume and heart rate variability



We investigated the effect of post-exercise sauna bathing on plasma volume (PV) expansion and whether such responses can be tracked by changes in heart rate (HR)-based measures.


Seven, well-trained male cyclists were monitored for 35 consecutive days (17 days baseline training, 10 days training plus sauna, 8 days training). Sauna exposure consisted of 30 min (87 °C, 11 % relative humidity) immediately following normal training. Capillary blood samples were collected while resting seated to assess PV changes. HR (HRwake) and vagal-related HR variability (natural logarithm of square root mean squared differences of successive R–R intervals, ln rMSSDwake) were assessed daily upon waking. A sub-maximal cycle test (5 min at 125 W) was performed on days 1, 8, 15, 22, 25, 29, and 35 and HR recovery (HRR60s) and ln rMSSDpostex were assessed post-exercise. Effects were examined using magnitude-based inferences.


Compared with baseline, sauna resulted in: (1) peak PV expansion after four exposures with a likely large increase [+17.8 % (90 % confidence limits, 7.4; 29.2)]; (2) reduction of HRwake by a trivial-to-moderate amount [−10.2 % (−15.9; −4.0)]; (3) trivial-to-small changes for ln rMSSDwake [4.3 % (1.9; 6.8)] and ln rMSSDpostex [−2.4 % (−9.1; 4.9)]; and (4) a likely moderate decrease in HRR60s [−15.6 % (−30.9; 3.0)]. Correlations between individual changes in PV and HR measures were all unclear.


Sauna bathing following normal training largely expanded PV in well-trained cyclists after just four exposures. The utility of HR and HRV indices for tracking changes in PV was uncertain. Future studies will clarify mechanisms and performance benefits of post-training sauna bathing.

This is a preview of subscription content, log in to check access.

Fig. 1
Fig. 2
Fig. 3
Fig. 4



Coefficient of variation


Effect size






Heart rate

HRex :

Heart rate during the 5-min sub-maximal (125 W) exercise test


Heart rate recovery

HRR60s :

Heart rate recovery at 60 s post-exercise


Heart rate variability

HRwake :

Heart rate upon waking

ln rMSSDpostex :

Natural logarithm of the rMSSD following sub-maximal exercise

ln rMSSDwake :

Natural logarithm of the rMSSD upon waking


Plasma volume


Square root mean of the sum of the squared differences between adjacent normal R–R intervals


Smallest worthwhile change


Yo-Yo Intermittent recovery level 2 test


  1. Al Haddad H, Laursen PB, Chollet D, Ahmaidi S, Buchheit M (2011) Reliability of resting and postexercise heart rate measures. Int J Sports Med 32:598–605

    Article  CAS  PubMed  Google Scholar 

  2. Armstrong LE, Maresh CM, Castellani JW, Bergeron MF, Kenefick RW, LaGasse KE, Riebe D (1994) Urinary indices of hydration status. Int J Sport Nutr 4:265–279

    CAS  PubMed  Google Scholar 

  3. Borresen J, Lambert M (2007) Changes in heart rate recovery in response to acute changes in training load. Eur J Appl Physiol 101:503–511

    Article  PubMed  Google Scholar 

  4. Buchheit M (2014) Monitoring training status with HR measures: do all roads lead to Rome? Front Physiol 5:73. doi: 10.3389/fphys.2014.00073

    Article  PubMed Central  PubMed  Google Scholar 

  5. Buchheit M, Papelier Y, Laursen PB, Ahmaidi S (2007) Noninvasive assessment of cardiac parasympathetic function: postexercise heart rate recovery or heart rate variability? Am J Physiol Heart Circ Physiol 293:H8–10

    Article  CAS  PubMed  Google Scholar 

  6. Buchheit M, Laursen P, Al Haddad H, Ahmaidi S (2009) Exercise-induced plasma volume expansion and post-exercise parasympathetic reactivation. Eur J Appl Physiol 105:471–481

    Article  CAS  PubMed  Google Scholar 

  7. Buchheit M, Chivot A, Parouty J, Mercier D, Al Haddad H, Laursen P, Ahmaidi S (2010) Monitoring endurance running performance using cardiac parasympathetic function. Eur J Appl Physiol 108:1153–1167

    Article  PubMed  Google Scholar 

  8. Buchheit M, Voss SC, Nybo L, Mohr M, Racinais S (2011) Physiological and performance adaptations to an in-season soccer camp in the heat: associations with heart rate and heart rate variability. Scand J Med Sci Sports 21:e477–e485

    Article  CAS  PubMed  Google Scholar 

  9. Buchheit M, Racinais S, Bilsborough JC, Bourdon PC, Voss SC, Hocking J, Cordy J, Mendez-Villanueva A, Coutts AJ (2013) Monitoring fitness, fatigue and running performance during a pre-season training camp in elite football players. J Sci Med Sport 16:550–555

    Article  CAS  PubMed  Google Scholar 

  10. Cohen J (1988) Statistical power analysis for the behavioral sciencies. Routledge, London

    Google Scholar 

  11. Garrett A, Goosens N, Rehrer N, Patterson M, Cotter J (2009) Induction and decay of short-term heat acclimation. Eur J Appl Physiol 107:659–670

    Article  PubMed  Google Scholar 

  12. Garrett A, Rehrer N, Patterson M (2011) Induction and decay of short-term heat acclimation in moderately and highly trained athletes. Sports Med 41:757–771

    Article  PubMed  Google Scholar 

  13. Garrett A, Creasy R, Rehrer N, Patterson M, Cotter J (2012) Effectiveness of short-term heat acclimation for highly trained athletes. Eur J Appl Physiol 112:1827–1837

    Article  PubMed  Google Scholar 

  14. Hopkins W (2000) Measures of Reliability in Sports Medicine and Science. Sports Med 30:1–15

    Article  CAS  PubMed  Google Scholar 

  15. Hopkins W (2006) Spreadsheets for analysis of controlled trials, with adjustment for a subject characteristic. Sportscience 10:46–50

    Google Scholar 

  16. Hopkins WG (2010) Linear models and effect magnitudes for research, clinical and practical applications. Sportscience 14:49–57 (sportsci.org/2010/wghlinmod.htm)

    Google Scholar 

  17. Hopkins W, Marshall S, Batterham A, Hanin J (2009) Progressive statistics for studies in sports medicine and exercise science. Med Sci Sports Exerc 41:3–13

    Article  PubMed  Google Scholar 

  18. Horowitz M, Peyser Y, Muhlrad A (1986a) Alterations in cardiac myosin isoenzymes distribution as an adaptation to chronic environmental heat stress in the rat. J Mol Cell Cardiol 18:511–515

    Article  CAS  PubMed  Google Scholar 

  19. Horowitz M, Shimoni Y, Parnes S, Gotsman M, Hasin Y (1986b) Heat acclimation: cardiac performance of isolated rat heart. J Appl Physiol 60:9–13

    CAS  PubMed  Google Scholar 

  20. Lamberts RP, Swart J, Noakes TD, Lambert MI (2011) A novel submaximal cycle test to monitor fatigue and predict cycling performance. Br J Sports Med 45:797–804

    Article  CAS  PubMed  Google Scholar 

  21. Lorenzo S, Halliwill J, Sawka M, Minson C (2010) Heat acclimation improves exercise performance. J Appl Physiol 109:1140–1147

    Article  PubMed Central  PubMed  Google Scholar 

  22. Lundvall J, Lindgren P (1998) F-cell shift and protein loss strongly affect validity of PV reductions indicated by Hb/Hct and plasma proteins. J Appl Physiol 84:822–829

    CAS  PubMed  Google Scholar 

  23. Morris S, Ruel M, Cohen R, Dewey K, de la Brière B, Hassan M (1999) Precision, accuracy, and reliability of hemoglobin assessment with use of capillary blood. Am J Clin Nutr 69:1243–1248

    CAS  PubMed  Google Scholar 

  24. Patterson M, Stocks J, Taylor N (2004) Sustained and generalized extracellular fluid expansion following heat acclimation. J Physiol 559:327–334

    Article  PubMed Central  CAS  PubMed  Google Scholar 

  25. Penttilä J, Helminen A, Jartti T, Kuusela T, Huikuri H, Tulppo M, Coffeng R, Scheinin H (2001) Time domain, geometrical and frequency domain analysis of cardiac vagal outflow: effects of various respiratory patterns. Clin Physiol 21:365–376

    Article  PubMed  Google Scholar 

  26. Plews DJ, Laursen PB, Stanley J, Kilding AE, Buchheit M (2013) Training adaptation and heart rate variability in elite endurance athletes: opening the door to effective monitoring. Sports Med 43:773–781

    Article  PubMed  Google Scholar 

  27. Racinais S, Buchheit M, Bilsborough J, Bourdon P, Cordy J, Coutts A (2014) Physiological and performance responses to a training-camp in the heat in professional australian football players. Int J Sport Physiol Perform 9:598–603

    Article  Google Scholar 

  28. Ridge B, Pyke F (1986) Physiological responses to combinations of exercise and sauna. Aust J Sci Med Sport 18:25–28

    Google Scholar 

  29. Saitoh T, Ogawa Y, Aoki K, Shibata S, Otsubo A, Kato J, Iwasaki K-i (2008) Bell-shaped relationship between central blood volume and spontaneous baroreflex function. Auton Neurosci 143:46–52

    Article  PubMed  Google Scholar 

  30. Sanchis-Gomar F, Cortell-Ballester J, Pareja-Galeano H, Banfi G, Lippi G (2013) Hemoglobin point-of-care testing: the hemocue system. J Lab Automation 18:198–205

    Article  Google Scholar 

  31. Sandercock G, Bromley P, Brodie D (2005) Effects of exercise on heart rate variability: inferences from meta-analysis. Med Sci Sports Exerc 37:433–439

    Article  PubMed  Google Scholar 

  32. Scoon GS, Hopkins W, Mayhew S, Cotter JD (2007) Effect of post-exercise sauna bathing on the endurance performance of competitive male runners. J Sci Med Sport 10:259–262

    Article  PubMed  Google Scholar 

  33. Shirreffs S, Armstrong L, Cheuvront S (2004) Fluid and electrolyte needs for preparation and recovery from training and competition. J Sports Sci 22:57–63

    Article  PubMed  Google Scholar 

  34. Stanley J, Peake J, Buchheit M (2013a) Consecutive days of cold water immersion: effects on cycling performance and heart rate variability. Eur J Appl Physiol 113:371–384

    Article  PubMed  Google Scholar 

  35. Stanley J, Peake JM, Buchheit M (2013b) Cardiac parasympathetic reactivation following exercise: implications for training prescription. Sports Med 43:1259–1277

    Article  PubMed  Google Scholar 

  36. Strauss M, Davis R, Rosenbaum J, Rossmeisl E (1951) “Water diuresis” produced during recumbency by the intravenous infusion of isotonic saline solution. J Clin Invest 30:862–868

    Article  PubMed Central  CAS  PubMed  Google Scholar 

  37. Task Force of the European Society of Cardiology and the North American Society of Pacing and Electrophysiology (1996) Heart rate variability: standards of measurement, physiological interpretation, and clinical use. Eur Heart J 93:1043–1065

    Google Scholar 

  38. Wallace L, Slattery K, Coutts A (2013) A comparison of methods for quantifying training load: relationships between modelled and actual training responses. Eur J Appl Physiol 114(1):11–20

    Article  PubMed  Google Scholar 

  39. Warburton D, Gledhill N, Quinney H (2000) Blood volume, aerobic power, and endurance performance: potential ergogenic effect of volume loading. Clin J Sport Med 10:59–66

    Article  CAS  PubMed  Google Scholar 

  40. Wyndham CH, Benade AJ, Williams CG, Strydom NB, Goldin A, Heyns AJ (1968) Changes in central circulation and body fluid spaces during acclimatization to heat. J Appl Physiol 25:586–593

    CAS  PubMed  Google Scholar 

Download references


The authors would like to thank the participants for their substantial commitment and assistance with the study. This study was funded by the Centre of Excellence for Applied Sport Science Research at the Queensland Academy of Sport. Aaron Halliday was supported by a scholarship from the Centre of Excellence for Applied Sport Science Research at Queensland Academy of Sport. Dr Jamie Stanley is supported by research grant funding from the Centre of Excellence for Applied Sport Science Research at Queensland Academy of Sport.

Conflict of interest

The remaining authors declare that they have no conflict of interest.

Ethical standard

The current experiment was conducted in Australia with all activities complying with the current laws of Australia.

Author information



Corresponding author

Correspondence to Jamie Stanley.

Additional information

Communicated by Keith Phillip George.

Rights and permissions

Reprints and Permissions

About this article

Verify currency and authenticity via CrossMark

Cite this article

Stanley, J., Halliday, A., D’Auria, S. et al. Effect of sauna-based heat acclimation on plasma volume and heart rate variability. Eur J Appl Physiol 115, 785–794 (2015). https://doi.org/10.1007/s00421-014-3060-1

Download citation


  • Heat exposure
  • Blood volume
  • Cardiac parasympathetic activity
  • Post-exercise
  • Cyclists