Hydration for Middle-Distance Runners

At Saturday, we are dedicated to optimizing athletic performance through sports nutrition. In today’s session, we will delve into the critical aspect of hydration during training for middle-distance runners, encompassing important elements such as liquid intake, the importance of sodium, and their impact on performance. For middle-distance runners, it's vital to attain and sustain optimal hydration levels.

Dehydration's Effect on Performance

A modest decrease in hydration, around 2%, can lead to a lowering of cardiac output, the amount of blood circulated by the heart each minute. This necessitates the heart to work more strenuously to pump blood, which can lead to a drop in performance.

As the state of dehydration intensifies, there is also a reduction in muscular power output. This can be attributed to the diminished blood volume, which impacts the efficient transportation of nutrients and oxygen to muscles. In addition, the body's ability to regulate temperature through sweating is compromised with ongoing fluid loss, which may result in an increase in core body temperature, negatively affecting performance.

Essential Balance: Hydration and Salt Levels

Achieving a balance between fluid levels and salt concentrations is fundamental during exercise. Dehydration is already a serious concern, but consuming an excess of water without sufficient salts can cause hyponatremia, which is characterized by a low sodium concentration in the blood plasma. Notably, the symptoms of hyponatremia such as headaches, confusion, fatigue, and muscle weakness, are strikingly similar to the symptoms of dehydration.

To sustain appropriate sodium levels in the blood, it is recommended to consume a hypotonic solution during training. However, as athletes often do not consume it in adequate amounts, a hypertonic solution might be needed to replace the sodium expended through sweating.

Fluid Intake Rates and Ratios

Middle-distance runners can typically consume between 0.8-1.5L of fluid per hour of training without encountering gastrointestinal discomfort, provided that the concentrations of sugar and electrolytes in the fluid are not excessively higher than that of the body's fluids (10-14% concentrations are generally recommended). In sessions that last less than three hours, consuming carbohydrate solutions with higher concentrations can be beneficial since the requirement for carbohydrate energy is prioritized over optimal water replenishment.

Customizing Electrolyte Consumption

It's crucial to personalize electrolyte consumption during training. Sodium needs usually span from 500-1500mg/L and are contingent on several variables, including perspiration rate, sweat composition, environmental temperature, and humidity. Generally, an increase in sweating demands a higher intake of sodium per liter to compensate for the losses.

Options for Replenishing Sodium

Various options for sodium replenishment are available, including specialized sports beverages, gels, and tabs. However, table salt is a cost-effective alternative. Sodium citrate is another efficient choice, providing a greater concentration of sodium ions compared to table salt. Sodium citrate splits into three sodium ions and one citrate ion, whereas table salt splits into one sodium ion and one chloride ion. This makes sodium citrate a denser source of sodium with minimized gastrointestinal impact.

The Bottom Line

Maintaining hydration is central to performance, with dehydration impacting cardiac output and muscle strength. It’s important to balance hydration with salt levels to avert dehydration and hyponatremia. Personalized fluid intake rates and electrolyte consumption are essential. Sodium can be replenished through various means, including table salt and sodium citrate. Understanding and adjusting hydration and electrolyte intake according to individual needs is vital.