Carbohydrate and water intake is 95% of the game in peaking. Go all in, bet the farm, but whatever you do; get carbs and water right. I spent all of "The Peaking Axis: Part I" nailing that to the wall. There is, however, another pair of corollaries that you can control to assist in your quest to be perfect—Sodium & Potassium.
I juxtapose those two because most competitors still increase potassium dramatically and cut sodium to near zero. Likely borrowed from blood pressure research, sodium and potassium certainly do make up most of the mineral content used cellularly to control the flow of water in and out of cells, however, I find viewing mineral balance/manipulation to be far more important on a broader level than just isolating sodium and potassium. Magnesium, calcium, and even less-considered minerals like sulfur all have a role in fluid dynamics.
I'm going to review some material I've written in the past and then help you pull it together into options for peak week and contest day. Keeping water intake high gives you the opportunity to be full. Take that to the bank.
Managing carbs to make sure you pull that water into the muscle tissue is critical - that's where you get your fullness... not the carbs, but the water the carbs attract. Thus, water has to be present. Being ultra-crisp, however, depends on what we do to keep it in the muscle cell. This is where the sodium/potassium comes in.
Sodium is the major extracellular fluid cation and potassium is the major intracellular fluid cation. Normal physiology maintains 55-65% of our fluid intracellularly anyway.
If we are in a normal condition, we have more fluid inside than outside our cells. It's when we screw something up that this percentage heads the other direction and fluid is diverted outside the cell.
Fluid dynamics is controlled with incredible precision via our kidneys. Though you hear the phrase "you have to trick your body" every time you get a locker room lesson on peaking, trust me, there is no tricking your body. It's much faster than you and much more sophisticated than you could hope to account for.
Every time you do something extreme trying to cause an extreme reaction, you'll get one. Two problems are that first, it may not be the one you wanted, and second, if it is what you wanted, it will be very short-lived because the extreme reaction will be quickly countered in the other direction just as severely until the "pendulum" that you violently swung slows back down.
Take a serious look at what happened to your body last time you peaked the way I described as wrong. You went from hard and full, to harder as you depleted carbs harshly, then a little smaller as you became severely depleted, then huge as carbs were reintroduced in massive amounts, then huge and soft as you spilled over, then soft and flat on the morning of the show due to being dehydrated after cutting water, then huge and vascular on Sunday as water was resumed (too late), and finally as soft and squishy as can be for a couple days after that. That's the kind of instability you get when you start trying to "trick" your body.
Water Follows Solutes
Yes, sodium and potassium are key ions that regulate cellular fluid dynamics, but you can't create extreme environments and expect to time them for a show. You can subtly influence them, but keep in mind this phrase: water follows solutes.
Water is attracted to and will follow the ions as they travel across the cell membranes. We want plasma to be attracted to the inside of the cell but it won't happen by just increasing potassium, it will be because we have the right balance of sodium and potassium.
The goal should be to simply maintain the "normal," stable environment that would have 55-65% of the fluid there anyway. Just as big a factor, however, is sodium's role in blood volume.
Deficiencies In Sodium
Deficiencies in sodium will lead to a drop in blood pressure which means plasma (water) has been pushed out of the vascular system. If it's not in your blood vessels, it's around them interstitially which means subcutaneously. That, of course, means smooth. This will then start a chain reaction that will take days to remedy.
When sodium is dropped from the diet, your kidneys will be influenced immediately by the hormone Aldosterone to conserve sodium from being excreted and remember; water follows solutes. If sodium is being resorbed, then water will be as well. You retain water and with the lower blood pressure, it's all under your skin instead of in your vascular system.
Take a look at this study:
Within one day of dropping dietary sodium, excreted sodium is cut in half and continues to decline as more Aldosterone is produced. But, look at blood levels of sodium: they're conserved perfectly! YOU CAN'T TRICK YOUR BODY! All you did by cutting sodium was screwed up the osmolarity of the cell membranes and you won't know where the water is going to go.
If you keep your water intake and sodium intake normal, your cellular fluid dynamics will stay normal. You'll continue to flush excess water and sodium out of your body. So, you ask, "What's normal?"
The RDA for sodium is a range of .5-2.4 grams per day but other sources recommend up to 3.3 grams per day. The RDA for potassium is 1.6-2.0 grams per day.
Multi Vitmain/Mineral
A multi-vitamin/mineral supplement is not only necessary, but often a specific multi-mineral supplement needs to be added just to keep normal levels due to high levels of water intake flushing minerals out of the body. Ever have problems with cramps—particularly at night? Take a multi-mineral supplement and they'll disappear. (If sodium is also adequate, that is.)
With that "base" of minerals stable, we can use sodium to keep the amount of water being retained in the body and in the muscle tissue that we want. Also due to minerals having the potential to be pushed out of the body when water intake is high, sodium is also actually too low and that can leave you horribly flat.
Potential Need For More Sodium
Sodium levels need to be kept normal and sometimes even increased toward the end of the week if carbs are being kept low-to-moderate. Once a client is a couple meals into Saturday morning I start assessing the potential need for more sodium. Why?
Because the short-term effect of having too little will lead to muscle cells leaking water... going flat. I may use a little table salt, but more likely would be a food that combines sodium and other needs such as quick acting carbs and possibly a little fat.
Peanut butter, pizza, and higher-sodium foods are typical in what I would want available if needed. Don't fall into the trap of thinking you have to manipulate something if you're maintaining the condition you want—the more carb-sensitive/endomorphic you are, you'll see a lesser need for increasing sodium.
Faster metabolisms create higher body temperatures, which lead to faster dehydration and sodium loss—these are the people who often need more water and more sodium leading up to the stage.
Conclusion
Again, it's very easy to major on the minors and get caught up in the high-tech details of physiology, but keep in mind stability is the key, not wild extremes. Majoring on the majors would make sure the primary peaking axis—water and carbs—is the primary concern. Get that right for the uniqueness of your body and you can peak with consistency and predictability.