Announcement

Collapse
No announcement yet.

A question of sodium loading

Collapse
X
 
  • Filter
  • Time
  • Show
Clear All
new posts

  • A question of sodium loading

    I put this short blog post together the other day, I'd be curious to hear what some of the coaches and athletes think.

    Sodium Loading

    Sodium loading is a pre-contest strategy used by bodybuilders during the final week/days of competitions to help obtain a dry and hard look while maximising muscularity.

    Now this is not really relevant for most unless you decide to do a bodybuilding show, however for those IIFYM guys and girls out there trust me when I say eating a bucket load of sodium laden foods will influence your appearance.

    Down the years I've only personally known a few athletes who have used this strategy (with disastrous consequences I might add) and I must admit it I've never tried it myself. Knowing how complex electrolyte balance can be I've always err on the edge of caution when advising fellow competitors who have thought about going down this route. Designing an effective sodium loading strategy remains a mystery to me.

    Strategies based on guess work like most things can be hit or miss. 9,000mg for one competitor might be too little or too much for another leading to disastrous consequences. Determining how much sodium should therefore depend on multiple variables at least for the sake of providing a better estimate. So what are those variables?

    Does anyway actually have experience with sodium loading? I've done a basic bit of textbook reading on electrolyte balance, sodium pumps and concentration so here's some relevant physiology:

    Sodium (Na) is transported within the cytosol across the cell membrane against a concentration gradient in a process called active transport via the Na potassium (K) ATPase pump. For this process to work potassium has to be present.

    In lay terms a cell pumps the sodium on the inside of the cell to the outside, while taking potassium on the outside of the cell to the inside. This is a consistent process. Within the body almost all of the sodium (99%) is held on the outside of the cell, while nearly all of the potassium is held on the inside of the cell. This pumping system maintains this balance.

    If you follow the link you can find a simple diagram demonstrating this process.

    CV Physiology: Na<sup>+</sup>/K<sup>+</sup>-ATPase

    Sodium can also transfer across the cell membrane in a process called secondary active transport. Since molecules always like to balance out in a fluid sodium will move from the outside of the cell into the inside of the cell. Almost like a ball running down a hill. Antiporters and Synporters transporters allow this process to happen, so when other molecules are transferred from the outside of the cell (like glucose or amino acids) some sodium is also transported. So the sodium content of a cell is at least dependent on the following from the diet sodium, potassium, Calcium, Water, Hydrogen, carbohydrates, and amino acids.

    However, If you remember the body uses the NaK/ATPase transporter to maintain balance, so you always have low sodium within the cell and high sodium on the outside of the cell.

    The reason it does this is because too much sodium within a cell is bad, sodium we know attracts water so if you suddenly had a massive influx of water you could potentially end up bursting the cells.

    Based on this physiology I've came up with two theory's on how sodium loading then works.

    1) either sodium loading causes a short term influx of fluid into the cell overriding the sodium potassium transporter until the body can regulate this excess sodium. Of course exercise would drive a large amount of sodium into the cell and away from organs within the intestinal tract taking with it any extracellular fluid.

    2) Sodium loading in the days prior to a contests causes the body to excrete large amounts of sodium and water to maintain fluid balance.

    Any thoughts?
    PhD Human Nutrition
Working...
X