Intravenous (IV) administration of fluids has been around for a long time as a way to treat clinical dehydration and heat illness, especially in the collapsed patient. IV treatment of severe dehydrations of >7% body weight loss, exertional heat illness, nausea, emesis, diarrhea and in those who cannot ingest oral fluids, is clinically indicated. (1) In the past IV administration of fluids has been reserved for these conditions that result from dehydration. For example, treatment of exercise-associated hyponatremia with hypertonic IV infusion to correct plasma sodium levels is a standard and accepted use of IV fluid infusions. (1) In these situations, IV administration of fluids can quickly and effectively rehydrate and treat the patient, potentially being life saving.
There has emerged an expanded role for IV hydration outside of the context of medical emergencies, such as for rapid treatment of dehydration and exercise associated muscle cramps (EAMC). (1) Proper hydration and rehydration is of great importance to athletes, as dehydration is linked to a decline in athletic performance. Among elite triathletes, muscle cramping is one of the most common reasons for not finishing. (1) IV rehydration and rehydration has been proposed as an ergogenic aid to achieve euhydration more effectively and efficiently. However, just because an athlete wants it, does that mean we should provide it? Time allowing, euhydration can be achieved in most individuals by drinking and eating normal beverages and meals. (1) If an athlete follows recommended pre and re-hydration recommendations, then hydration and re-hydration shouldn't be an issue for the average healthy athlete. Hydration should begin at least 4 hours before exercise, at a slow, steady rate of ~5-7 mL/kg, especially if known deficits are present. (1) Post-exercise, athletes should consume 1.5 L of fluid for each kg of body weight lost, replacing this 150% of body weight lost within 60 minutes is generally tolerated. (1)
There are many hurdles that need to be over come to implement IV therapy into the clinical setting outside the context of medical emergencies. Even in medical emergencies, the required supplies, personnel, training and education is too great for some settings to afford and implement into regular practice.
Lack of Evidence:
Probably the biggest, and most important hurdle to IV integration, is the overwhelming lack of supporting evidence. Convincing research supporting IV administration prior to competition for performance enhancement, dehydration prevention or muscle cramp prevention does not exist. In fact, current studies do not support use of IV fluids for rehydration when oral fluids are tolerated. (1) One of the biggest non-emergency conditions that athletes advocate IV fluids for is the treatment of EAMC. However, EAMC is a multifaceted issue, that hasn't been clearly or solely linked to hydration status or electrolyte concentration.(1) Furthermore, there's not really published studies on treating EAMC with iv fluids either. Despite the WDA concerns of routine IV fluid administration as a ergogenic aid, there is no research on iv fluids being used in this way and their effectiveness as an aid to performance. (1) Because of this, IV therapy cannot be recommended as best practice for majority of athletes.
Banned by WDA:
IV fluids and plasma binders are not permitted in WDA governed competitions. The rule is this: "Intravenous infusions and/or injections of more than 50 mL per 6 hour period are prohibited except for those legitimately received in the course of hospital admissions or clinical investigations" (1)(2) While most institutions and athletic competitions in the US are not governed by the WDA, the fact that IV therapy outside of the context of medical emergencies and investigations, should be understood and considered before implementing iv hydration into practice. Personally, in order to go against a large governing body, such as WDA, I would need sufficient evidence that IV therapy does what its being used for, in this case, quick and efficient rehydration during competition.
Increased Risk of IV over Oral intake:
Finally, even though the complications of IV administration are relatively low, they must still be considered. Complications and risks include: infection, bleeding, soft tissue infiltration and air embolism. (1) All of these are complications that are nonexistent in oral hydration. Iv administration requires appropriately trained medical staff and a hygienic and safe environment, if these are unavailable the risk of complications increases greatly.
While I think there is a long way to go before IV administration becomes a safe, readily available option for healthy athletes, it should not be negated that there are assumed benefits and teams who currently practice use of IV fluids to hydrate athletes. Though there have been no cardiovascular, thermoregulatory or performance benefits found, IV fluid administration is a perceived ergogenic aid. It allows quick and "easy" hydration through large volumes of fluid given over a short period of time. (1)(2) Though the ideal rate of fluid intake via IV administration has not been determined in healthy individuals, an 18G IV can provide 50-60 mL/minute by gravity. (1)
When it comes down to it, athletic trainers have the ability to become trained and administer IV fluids, however whether or not they do should be based on research and their ability to do so safely, in their setting.
(1 )Givan GV, Diehl JJ. Intravenous fluid use in athletes. Sports Health. 2012;4(4):333-339.
(2) Coombes JS, van Rosendal SP. Use of intravenous rehydration in the National Football League. In: LWW; 2011.
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