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

Abstract

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.

Efeitos agudos do exercício físico prolongado: avaliação após ultramaratona de 24 horas

“…Recently, Knechtle et al 22 found a mean reduction of 2.5% in the weight of athletes after a 100-km ultramarathon, which can not be totally explained by the reduction in total body water, suggesting that the loss resulted from solid mass loss (muscle mass and fat).…”

“…2013;100(1): [21][22][23][24][25][26][27][28] exercise at high temperatures 18 . It is noteworthy in our study the close inverse association observed between CPK levels and the covered distance.…”

Ultramarathon Running: Medical Issues

“…Therefore, athletes who drink less during ultra-marathon running may profit from body mass loss and complete the race faster [57]. Also in a 160-km ultra-marathon, greater loss in body mass during the race was not associated with impaired performance but was rather an aspect of superior performance [60].…”

“…In a 100-km ultra-marathon, faster runners drank more fluid than slower runners and faster runners lost more body mass than slower runners. Additionally, runners lost more body mass when they drank less fluid [57].…”

“…However, there seemed to be no need to consume excessive amounts of fluid in ultramarathon running [57]. Generally, ultra-marathoners seemed not to overdrink [58] and no fluid overload should occur during an ultra-marathon [59].…”