Maintenance of Plasma Volume and Serum Sodium Concentration Despite Body Weight Loss in Ironman Triathletes

Hew‐Butler, Tamara; Collins, Malcolm; Bosch, Andrew; Sharwood, Karen; Wilson, Gregory D.; Armstrong, Miranda; Jennings, Courtney; Swart, Jeroen; Noakes, Timothy D.

doi:10.1097/jsm.0b013e3180326836

Cited by 53 publications

(43 citation statements)

References 47 publications

(68 reference statements)

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“…In another study on 181 male Ironman triathletes, plasma volume and serum [Na + ] were maintained despite a significant body mass loss of 5% (Hew-Butler, et al, 2007). These authors concluded that body mass was not an accurate 'absolute' surrogate of fluid balance homeostasis during prolonged endurance exercise.…”

Section: Discussionmentioning

confidence: 89%

A faster running speed is associated with a greater body weight loss in 100-km ultra-marathoners

Knechtle¹,

Knechtle²,

Wirth³

et al. 2012

Journal of Sports Sciences

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In 219 recreational male runners, we investigated changes in body mass, total body water, haematocrit, plasma sodium concentration ([Na(+)]), and urine specific gravity as well as fluid intake during a 100-km ultra-marathon. The athletes lost 1.9 kg (s = 1.4) of body mass, equal to 2.5% (s = 1.8) of body mass (P < 0.001), 0.7 kg (s = 1.0) of predicted skeletal muscle mass (P < 0.001), 0.2 kg (s = 1.3) of predicted fat mass (P < 0.05), and 0.9 L (s = 1.6) of predicted total body water (P < 0.001). Haematocrit decreased (P < 0.001), urine specific gravity (P < 0.001), plasma volume (P < 0.05), and plasma [Na(+)] (P < 0.05) all increased. Change in body mass was related to running speed (r = -0.16, P < 0.05), change in plasma volume was associated with change in plasma [Na(+)] (r = -0.28, P < 0.0001), and change in body mass was related to both change in plasma [Na(+)] (r = -0.36) and change in plasma volume (r = 0.31) (P < 0.0001). The athletes consumed 0.65 L (s = 0.27) fluid per hour. Fluid intake was related to both running speed (r = 0.42, P < 0.0001) and change in body mass (r = 0.23, P = 0.0006), but not post-race plasma [Na(+)] or change in plasma [Na(+)] (P > 0.05). In conclusion, faster runners lost more body mass, runners lost more body mass when they drank less fluid, and faster runners drank more fluid than slower runners. AbstractWe investigated in 219 recreational male runners the changes (Δ) in body mass, total body water, haematocrit, plasma sodium concentration ([Na + ]) and urine specific gravity as well as fluid intake during a 100-km ultra-marathon. The athletes lost 1.9 (s = 1.4) kg of body mass, equal to 2.5 (s = 1.8) % in body mass (P < 0.001), 0.7 (s = 1.0) kg of predicted skeletal muscle mass (P < 0.001), 0.2 (s = 1.3) kg of predicted fat mass (P < 0.05) and 0.9 (s = 1.6) L of predicted total body water (P < 0.001). Haematocrit decreased (P < 0.001), urine specific gravity (P < 0.001), plasma volume (P < 0.05), and plasma [Na + ] (P < 0.05) increased.

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Section: Discussionmentioning

confidence: 89%

A faster running speed is associated with a greater body weight loss in 100-km ultra-marathoners

Knechtle¹,

Knechtle²,

Wirth³

et al. 2012

Journal of Sports Sciences

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“…2 In single Ironman triathlons, exercise-associated hyponatremia (EAH) is considered a frequent and serious problem. 3,4 EAH is defined as a decrease in plasma [Na + ] concentration < 135 mmol/l 5 and fluid overload is the likely aetiology. 4,6 However, regarding recent findings,…”

Section: Introductionmentioning

confidence: 99%

Effect of a Multistage Ultraendurance Triathlon on Aldosterone, Vasopressin, Extracellular Water and Urine Electrolytes

et al. 2012

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Prolonged endurance exercise over several days induces increase in extracellular water (ECW). We aimed to investigate an association between the increase in ECW and the change in aldosterone and vasopressin in a multistage ultraendurance triathlon, the 'World Challenge Deca Iron Triathlon' with 10 Ironman triathlons within 10 days. Before and after each Ironman, body mass, ECW, urinary [Na(+)], urinary [K(+)], urinary specific gravity, urinary osmolality and aldosterone and vasopressin in plasma were measured. The 11 finishers completed the total distance of 38 km swimming, 1800 km cycling and 422 km running within 145.5 (18.8) hours and 25 (22) minutes. ECW increased by 0.9 (1.1) L from 14.6 (1.5) L prerace to 15.5 (1.9) L postrace (P < 0.0001). Aldosterone increased from 70.8 (104.5) pg/mL to 102.6 (104.6) pg/mL (P = 0.033); vasopressin remained unchanged. The increase in ECW was related neither to postrace aldosterone nor to postrace vasopressin. In conclusion, ECW and aldosterone increased after this multistage ultraendurance triathlon, but vasopressin did not. The increase in ECW and the increase in aldosterone were not associated.

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“…This suggests that body mass change may not accurately represent the net effective body water change during prolonged exercise. However, this matter is hotly debated today, because some researchers have reported a difference between body mass change and net effective body water change (Hew-Butler et al, 2007;Nolte, Noakes, & Van Vuuren, 2011;Tam et al, 2011), whereas other investigators have reported no difference (Baker, Lang, & Kenney, 2009). Thus, the present field investigation determined if (a) body mass change was equivalent to effective body water change during ultra-endurance exercise and (b) the changes of body mass change and effective body water would be similar in three cyclist groups, with different exercise durations and ground speeds.…”

Section: Discussionmentioning

confidence: 96%

“…First, is water bound to glycogen and released only when glycogen is metabolised, or is this water freely available within the intracellular space at all times? This question is still debated today , with some authors claiming that water is bound to glycogen (Hew-Butler et al, 2007;King et al, 2008;Pastene, Germain, Allevard, Gharib, & Lacour, 1996;Rogers et al, 1997;Tam et al, 2011; and others proposing that this intracellular water is freely available as part of the total body water pool and not part of intracellular water gain (Baker et al, 2009;Cheuvront & Haymes, 2001;King et al, 2008). Second, if water is chemically bound to glycogen, what is the mass ratio of glycogen to water?…”

Section: Water Associated With Glycogenmentioning

confidence: 98%

Effective body water and body mass changes during summer ultra-endurance road cycling

Armstrong

Johnson

Ganio

et al. 2014

Journal of Sports Sciences

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Because body mass change (ΔMb) does not represent all water losses and gains, the present field investigation determined if (a) ΔMb equalled the net effective body water change during ultra-endurance exercise and (b) ground speed and exercise duration influenced these variables. Thirty-two male cyclists (age range, 35-52 years) completed a 164-km event in a hot environment, were retrospectively triplet matched and placed into one of three groups based on exercise duration (4.8, 6.3, 9.6 h). Net effective body water loss was computed from measurements (body mass, total fluid intake and urine excreted) and calculations (water evolved and mass loss due to substrate oxidation, solid food mass and sweat loss), including (ΔEBWgly) and excluding (ΔEBW) water bound to glycogen. With all cyclists combined, the mean ΔMb (i.e. loss) was greater than that of ΔEBWgly by 1200 ± 200 g (P = 1.4 × 10(-18)), was similar to ΔEBW (difference, 0 ± 200 g; P = .21) and was strongly correlated with both (R(2) = .98). Analysis of equivalence indicated that ΔMb was not equivalent to ΔEBWgly, but was equivalent to ΔEBW. Due to measurement complexity, we concluded that (a) athletes will not calculate the effective body water calculations routinely and (b) body mass change remains a useful field-expedient estimate of net effective body water change.

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Maintenance of Plasma Volume and Serum Sodium Concentration Despite Body Weight Loss in Ironman Triathletes

Cited by 53 publications

References 47 publications

A faster running speed is associated with a greater body weight loss in 100-km ultra-marathoners

A faster running speed is associated with a greater body weight loss in 100-km ultra-marathoners

Effect of a Multistage Ultraendurance Triathlon on Aldosterone, Vasopressin, Extracellular Water and Urine Electrolytes

Effective body water and body mass changes during summer ultra-endurance road cycling

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