The reported magnitude of plasma volume increase (Δ%PV) following heat acclimation (HA) varies widely. Variations may result from differences in measurement techniques, season and subjects’ fitness. This report compares direct and indirect measurements of Δ%PV after 10 days of HA from studies in winter (WIN, n = 8) and summer (SUM, n = 10) in men, age 21–43 yr, at two fitness levels (VO2max: 35 and 51 ml/min/kg). Direct measurements were made before and after HA (cycling at 30% of VO2max at 50 °C, for 100 min/day) by carbon monoxide (CO) rebreathing and compared with indirect estimates from changes in hematocrit, hemoglobin and plasma protein concentration.
Overall, Δ%PV by CO was small (2.9%) and greater in SUM than WIN (5.0 vs. 0.3%). Red cell, blood and plasma volumes/kg lean body mass increased in SUM and decreased in WIN, the difference being significant, and Δ%PV by CO was similar for high and low VO2max.
Overall, indirect estimates of Δ%PV by hemoglobin and hematocrit were similar to CO, but tended to differentiate by fitness and not season. The difference in THb increase in SUM and decrease in WIN was significant. This probably accounts for the differences from the seasonal and fitness results by the direct CO method.
Armstrong LE , Maresh CM: The induction and decay of heat acclimatisation in trained athletes. Sports Med. 12, 302–312 (1991)
Banfi G , Lundby C, Robach P, Lippi G: Seasonal variations of haematological parameters in athletes. Eur. J. Appl. Physiol. 111, 9–16 (2011)
Bass DE , Buskirk ER, Iampietro PF, Mager M: Comparison of blood volume during physical conditioning, heat acclimatization and sedentary living. J. Appl. Physiol. 12, 186–188 (1958)
Burge CM , Skinner SL: Determination of hemoglobin mass and blood volume with CO: evaluation and application of a method. J. Appl. Physiol. 79, 623–631 (1995)
Cadarette BS , Sawka MN, Toner MM, Pandolf KB: Aerobic fitness and the hypohydration response to exerciseheat stress. Aviat. Space Environ. Med. 55, 507–512 (1984)
Cheung SS , McLellan TM: Heat acclimation, aerobic fitness, and hydration effects on tolerance during uncompensable heat stress. J. Appl. Physiol. 84, 1731–1739 (1998)
Drabkin DL : The standardization of hemoglobin measurement. Am. J. Med. Sci. 215, 110–111 and. 217, 710–711 (1948–1949)
Fortney SM , Senay LC, Jr: Effect of training and heat acclimation on exercise responses of sedentary females. J. Appl. Physiol. Respir. Environ. Exerc. Physiol. 47, 978–984 (1979)
Garrett AT , Creasy R, Rehrer NJ, Patterson MJ, Cotter JD: Effectiveness of short-term heat acclimation for highly trained athletes. Eur. J. Appl. Physiol. 112, 1827–1837 (2012)
Garrett AT , Goosens NG, Rehrer NJ, Patterson MJ, Harrison J, Sammut I, Cotter JD: Short-term heat acclimation is effective and may be enhanced rather than impaired by dehydration. Am. J. Hum. Biol. 26, 311–320 (2014)
Gore CJ , Hopkins WG, Burge CM: Errors of measurement for blood volume parameters: a meta-analysis. J. Appl. Physiol. 99, 1745–1758 (2005)
Green HJ , Thomson JA, Ball ME, Hughson RL, Houston ME, Sharratt MT: Alterations in blood volume following short-term supramaximal exercise. J. Appl. Physiol. Environ. Exerc. Physiol. 56, 145–149 (1984)
Greenleaf JE , Convertino VA, Mangseth GR: Plasma volume during stress in man: osmolality and red cell volume. J. Appl. Physiol. Respir. Environ. Exerc. Physiol. 47, 1031–1038 (1979)
Harrison MH , Edwards RJ, Graveney MJ, Cochrane LA, Davies JA: Blood volume and plasma protein responses to heat acclimatization in humans. J. Appl. Physiol. Respir. Environ. Exerc. Physiol. 50, 597–604 (1981)
Hightower CM , Hightower JD, Vázquez BY, Intaglietta M: Seasonal hematocrit variation and health risks in the adult population of Kinshasa, Democratic Republic of Congo. Vasc. Health Risk Manag. 5, 1001–1005 (2009)
Hoekstra T , Veldhuizen I, van Noord PA, de Kort WL: Seasonal influences on hemoglobin levels and deferral rates in whole-blood and plasma donors. Transfusion. 47, 895–900 (2007)
Kristal-Boneh E , Froom P, Harari G, Shapiro Y, Green MS: Seasonal changes in red blood cell parameters. Br. J. Haematol. 85, 603–660 (1993)
Lim TP , Luft UC: Body density, fat, and fat-free weight. Am. J. Med. 30, 825–832 (1961)
Lindinger MI , McCutcheon LJ, Ecker GL, Geor RJ: Heat acclimation improves regulation of plasma volume and plasma Na(+) content during exercise in horses. J. Appl. Physiol. 88, 1006–1013 (2000)
Loeppky JA , Luft UC: Work capacity, exercise responses and body composition of professional pilots in relation to age. Aviat. Space Environ. Med. 60, 1077–1084 (1989)
Loeppky JA , Myhre LG, Venters MD, Icenogle MV, Kobayashi Y: Effects of running training and hypovolemia on LBNP tolerance. Advances in Exercise and Sports Physiology. 11, 69–76 (2005)
Lorenzo S , Halliwill JR, Sawka MN, Minson C: Heat acclimation improves exercise performance. J. Appl. Physiol. 109, 1140–1147 (2010)
Luft UC , Cardus D, Lim TP, Anderson EC, Howarth J: Physical performance in relation to body size and composition. Ann. NY Acad. Sci. 110, 795–808 (1963)
Luft UC (1973): Body fluids and electrolytes under conditions of single and combined stress. In: Report on Specialized Physiological Studies in Support of Manned Space Flight, contract NAS 9-12572 February; NASA, LBJ Space Center, Biomedical Research Division, Houston, TX. pp. C1–C18
Luft UC (1976): A study of factors affecting tolerance to gravitational stress simulated by lower body negative pressure. In: Report on Specialized Physiological Studies in Support of Manned Space Flight, contract NAS 9-14472 February; NASA, LBJ Space Center, Biomedical Research Division, Houston, TX. pp I1–I27
Myhre LG , Brown DK, Hall FG, Dill DB: The use of carbon monoxide and T-1824 for determining blood volume. Clin. Chem. 14, 1197–1205 (1968)
Myhre LG : Comparison of manometric and infrared methods for determining carbon monoxide in blood. Clin. Chem. 18, 909–910 (1972)
Pandolf KB : Time course of heat acclimation and its decay. Int. J. Sports Med. 19(Suppl 2), S157–S160 (1998)
Patterson MJ , Stocks JM, Taylor NA: Sustained and generalized extracellular fluid expansion following heat acclimation. J. Physiol. 559(Pt 1), 327–334 (2004)
Sawka MN , Convertino VA, Eichner ER, Schnieder SM, Young A: Blood volume: importance and adaptations to exercise training, environmental stresses, and trauma/sickness. Med. Sci. Sports Exerc. 32, 332–334 (2000)
Sawka, MN , Coyle EF (1999): Influence of body water and blood volume on thermoregulation and exercise performance in the heat. In Exercise and Sport Sciences Reviews, ed Hollozsy JO, Williams & Wilkins, Baltimore, MD, pp. 167–218
Schmidt W , Maassen N, Trost F, Böning D: Training effects on blood volume, erythrocyte turnover and haemoglobin oxygen binding properties. Eur. J. Physiol. Occup. Physiol. 57, 490–498 (1988)
Sebok MA , Notari EP, Chambers LA, Benjamin RJ, Eder AF: Seasonal temperature variation and the rate of donor deferral for low hematocrit in the American Red Cross. Transfusion. 47, 890–894 (2007)
Shapiro Y , Hubbard RW, Kimbrough CM, Pandolf KB: Physiological and hematologic responses to summer and winter dry-heat acclimation. J. Appl. Physiol. Respir. Environ. Exerc. Physiol. 50, 792–798 (1981)
Shiraki K , Yamada T, Yoshimura H: Relation of protein nutrition to the reduction of red blood cells induced by physical training. Jpn. J. Physiol. 27, 413–421 (1977)