Study of Hematological and Biochemical Parameters in Runners Completing a Standard Marathon

Abstract

This study found no cases of hyponatremia in runners completing a standard distance marathon. This finding relates to a marathon run under ideal conditions (minimal climatic stress) and in which there were fewer aid stations (every 5 km) than is common in North American marathons (every 1.6 km). Also, aggressive hydration practices were not promoted. Consumption of NSAIDs in the 24 hours prior to distance running was associated with altered renal function.

Exercise-Associated Hyponatremia

“…Several studies have examined the incidence of hyponatremia in this cohort, and a range of 6 to 30% of these athletes had serum sodium values below normal (9,10,12,(15)(16)(17)(18)(19)(20)(21)(22)(23)(24)(25). The wide range of incidence likely reflects differences in fluid replacement guidelines that were prevalent at the time and place of the study.…”

“…However, recent studies have shown that endurance athletes not uncommonly develop hyponatremia at the end of the race, usually in the absence of clear central nervous system symptoms (9,10,12,(15)(16)(17)(18)(19)(20)(21)(22)(23)(24)(25). For example, in the 2002 Boston Marathon, Almond et al (15) found that 13% of 488 runners studied had hyponatremia (defined as a serum sodium concentration of 135 mmol/L or less) and 0.6% had critical hyponatremia (serum sodium concentration of 120 mmol/L or less).…”

“…Nonsteroidal anti-inflammatory drug (NSAID) use is common among marathon runners, being used in 50 to 60% of men and women, respectively (10,22,47). NSAID are known to potentiate the effects of arginine vasopressin (AVP) by inhibiting renal prostaglandin synthesis via the COX-2 isoform of cyclo-oxygenase (48 -50).…”

“…Despite these theoretical considerations, Almond et al (15) were unable to associate the use of NSAID with the development of hyponatremia in the runners who were studied in the 2002 Boston Marathon. Other studies also have not been able to ascribe conclusively to NSAID use the development of hyponatremia, although several of these studies were underpowered to do so (10,22). However, a recent study in 330 triathletes demonstrated a significant association of NSAID use and the development of hyponatremia (23).…”

Resposta da frequência cardíaca e da concentração de lactato após cada segmento do triathlon olímpico

“…Some studies support the ratio between these two variables in the process adaptation during the training season and in competitions in several modalities, such as in skaters 6 , cyclists 7,8 , runners 9,10 and racing drivers 11 . The aim of our study was to observe whether there is straight relation between exercise intensities and the physiological variables of exertion prediction during an Olympic triathlon event, relating the heart rate values and blood lactate concentration after the performance of each of the segments-modality: swimming, cycling and running.…”