Workload of Water Polo Players Following a Phosphorus Manipulated High Carbohydrate Meal

The use of phosphorus as ergogenic aid has been widely reported and researched (Buck et al, 2013). Most of the research has centered on its chronic intake effect, usually for a loading period of 3-6 days (Kopec et al, 2015). The benefits of phosphate supplementation on athletic performance have been attributed to several potential factors, like increased maximal oxygen uptake and improved cardiac output (Folland et al, 2008). The underlying mechanisms were hypothesized to be the increased plasma content in 2.3-DPG (2.3-disphosphoglycerate) which may be a factor in reduced oxygen affinity to hemoglobin and consequent enhanced release in the exercising tissue (Di Caprio et al, 2015). Other lines of investigation, which were based on blood analysis and hypophosphatemia's effect on metabolism (Lichtman et al, 1971), and the rate of glycogenolysis in exercising muscle and rate of inorganic phosphorus (Chasiotis, 1988), attribute the beneficial effects of phosphate supplementation to higher extracellular concentration leading to increased ATP formation. A positive effect of phosphate supplementation was detected independently of 2.3-DPG in a recent study (Czuba et al, 2009). Additionally, increased phosphate availability was reported to increase peripheral glucose uptake (Khattab et al 2015) and stimulate glycogen synthesis (Xie et al, 2000). The failure of acute phosphate supplementation alone, without carbohydrate, to affect athletic performance (Galloway et al, 1996) may be partially attributed to low glycogen availability. We hypothesize that phosphorus exerts its effect acutely through increasing glycogen content of liver and muscles. Hence the acute effect of Phosphorus in physiologic doses on athletic performance may reveal another aspect of phosphate supplementation. If an improvement in work output is detected, as a significant difference in Metabolic Equivalent of Tasks (METs) and workload would indicate, it could be interpreted as a result of a higher glycogen formation leading to increased work output due to muscle signaling (Rauch et al, 2005). The current trial will allow 3 hours of absorption to estimate the likely benefit of phosphorus supplementation through enhanced glucose uptake possibly limited by phosphorus depletion under normal conditions, as noticed in the experiment of Khattab et al. (2015). The risk of change in blood osmolality due to administration of 100gr of Dextrose usually used in OGTT is minimal (Finta et al, 1992) .

Methods:

Inclusion criteria: AUB water polo players who are between the age of 18 and 25 years old, shall be included in the study.

Risk assessment: It should be noted that the university requires a clearance from Family Medicine following a general health and cardiac screening (ECG) for inclusion on a varsity team, which indicates that the trial includes no increased risk for the participating athletes. The health survey filled by the Family Medicine department physician includes presence of allergies and previous medical conditions.

A cross over study will be conducted on 17 male athletes (all members of the American University of Beirut's Water Polo Varsity Team), that are known to have similar energy expenditure and exercise patterns. Overnight fasted subjects will be depleted of glycogen. Participants will be asked to cycle for 20 min at 65% of each one's VO2max (that is determined prior to the experiment), thereafter will be given a meal (100g of glucose dissolved in 300 ml) with 4 tablets of phosphorus (100mg/tablet) or placebo in a random order.