Human Albumin Synthesis Is Increased by an Ultra-Endurance Trial

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MISCHLER, I., Y. BOIRIE, P. GACHON, V. PIALOUX, R. MOUNIER, P. ROUSSET, J. COUDERT, and N. FELLMANN. Human Albumin Synthesis Is Increased by an Ultra-Endurance Trial. Med. Sci. Sports Exerc., Vol. 35, No. 1, pp. 75–81, 2003. Purpose The purpose of this study was to determine whether an ultra-endurance event is a strong stimulus to increase albumin synthesis involved in the process of intravascular albumin mass increase associated with transient hypervolemia. Methods The albumin synthetic rate was measured in six young men, 3 d before (C) and on the 1st (R1) and 8th (R8) days of the recovery from an ultra-endurance trial (5 h daily for 4 d). Albumin fractional (FSR) and absolute (ASR) synthetic rate were determined using a primed-constant infusion of [1-13C] leucine. Plasma volume (PV) using Evans Blue dye dilution and total body water (TBW) using bioelectrical impedance analysis were measured on C, R1, and R8. Results On R1 as compared with C: 1) PV (+23.3 ± 3.2%;P ≤ 0.001) and TBW (+4.2 ± 0.8%;P ≤ 0.01) expanded; 2) FSR and ASR both increased from 5.36 ± 0.46 to 6.86 ± 0.62%·24 h−1 (+ 29.0 ± 7.1%;P ≤ 0.01) and from 103 ± 10 to 153 ± 19 mg·kg body weight−1·24 h−1 (+47.5 ± 6.8%;P ≤ 0.01); and 3) plasma albumin and protein masses increased (P ≤ 0.05) from 1.92 ± 0.08 to 2.22 ± 0.14 g·kg body weight−1 (i.e., +15.3 ± 4.9%) and from 3.15 ± 0.18 to 3.56 ± 0.21 g·kg body weight−1 (+13.3 ± 3.9%), respectively. By R8, all these parameters had returned to their control levels except for albumin mass (1.73 ± 0.08 g·kg body weight−1), which was lower than C (P ≤ 0.05). Conclusion The increase in the albumin synthetic rate the day after an ultra-endurance trial is a major event associated with a greater circulating protein mass. The impact of exercise on albumin synthesis has disappeared 8 d later, as did PV and total protein mass expansion.