Race Day Nutrition (Part Six) – Marc Laithwaite

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Having discussed carbohydrate, fluid and salt intake, I thought it would be prudent to focus a little more on application. We’ll take a look at the specific products used during endurance events and whether they can fulfil your requirements in terms of nutrition intake.

There are 3 common sports products used during endurance racing:

  1. Drinks powders
  2. Gels
  3. Bars

Aside from the ‘big 3’ there is also a selection of jelly shots or chews, in addition to traditional favourites such as jelly babies, malt loaf, flapjack and bananas. For the purpose of this blog, we’re going to focus on the big 3 and examine what they provide and what’s the difference between them?

Energy Drinks

Energy drinks generally come in powder form and you mix with water to create a solution. In past blogs we’ve discussed the isotonic issue and how it impacts upon digestion. Based upon that, a 10% solution or less is ideal (7% is isotonic). To create a 10% solution, mix 60g of powder in 600ml of water.

What’s in the powder?

Almost all energy powders are maltodextrin, this is a ‘glucose polymer’ and made up of between 3-17 pieces of glucose in a chain. It is very rapidly absorbed (almost as quickly as pure glucose) and therefore gives a rapid sugar spike and insulin response (good if you need it during racing, but not good if you don’t need it, such as steady training or just using during the day as part of your diet). All energy drinks tend to be based on maltodextrin, but they often have small amounts of glucose and fructose.

Electrolytes

We discussed sweating and hydration last week, which included salt intake. You can go back and read in full if you wish, but as a recap, salt and sodium are 2 different things. Salt is 40% sodium and 60% chloride. You need to know this as some products give ‘salt’ content and others give ‘sodium’ content. Remember also from last week we said that you are likely to sweat up to 1g of sodium per hour (1000mg). There’s multiple thoughts on salt replacement, regarding how much and whether you need it. I’m not going to go into depth on the matter because this is meant to be a simple and easy to read blog. If it’s warm and you sweat a fair bit, aim for 500-1000mg SODIUM per hour. If you take a bit too much, you’ll just sweat it out anyhow so don’t overly panic.

Let’s presume that you are aiming to take all of your energy by using sports drinks. So remember, our targets are 60g of carbohydrate per hour and 500-1000mg of sodium per hour, presuming its warm and you sweat. Here are some options:


SIS GO Electrolyte 60 grams of powder

Includes 55 grams of carbohydrate, primarily maltodextrin

360mg sodium

 

Powerbar Iso Active 60 grams of powder

53 grams of carbohydrate, primarily maltodextrin

756mg sodium

 

H5 Energy Source 60 grams of powder

57g of carbohydrate, includes maltodextrin, but 33% fructose

312mg sodium

 

H5 Energy Source Xtrem 60 grams of powder

57g of carbohydrate 33% fructose

306mg sodium

Approx. 175mg caffeine

 

Some key points:

  1. We said your target is 60g of carbohydrate, not 60g of powder, but as you can see above, 95% of the powder which goes into your bottle, is actual carbohydrate.
  1. The sodium levels vary quite widely, you can see that Powerbar Iso Active has considerably more than others (756mg) and is the only one to fall within the 500-100mg range.
  1. H5 Energy Source is the only one which uses fructose in large quantities. They use a 2:1 formula (66% maltodextrin and 33% fructose). The reason for this is that the 60g per hour rule is based on the fact that only 60g of GLUCOSE can be absorbed per hour (maltodextrin is a glucose chain). However, that doesn’t account for fructose, which is absorbed in a different manner. So basically, if you take 90g of powder per hour, that contains 60g glucose (the maximum amount of glucose you can absorb) and 30g fructose which is absorbed separately. You can use this drink to take on more carbohydrate per hour than the normal guidelines.
  1. H5 Extrem also has caffeine, approx 175mg per 60g powder. To put that into perspective a pro-plus tablet has 50mg and a filter coffee has between 50-100mg per cup. People think caffeine is a ‘pick up’ or ‘kick’, when in fact it’s real purpose is a pain killer. Caffeine can mask your effort if taken in significant quantities, it changes your perception by acting on the nervous system to make things feel easier.


What about electrolyte tablets?


H5 Zero Tabs 4g tablet

260mg sodium

Power Bar 4g tablet

250mg sodium


Some key points:

The electrolyte tablets don’t contain any energy, they are purely flavoured salt replacement. If you’re drinking a bottle every hour in warm weather and sweating, then you probably need to double them in the bottle. If you’re using energy gels and bars to get your ‘energy’ during your event, you could use the electrolyte tablets to reach your sodium target. You can generally always get water during a race, so add 2 tabs to each bottle and drinks throughout the hour in addition to taking your gels and or bars.

I hope that basic overview of drinks helps you to practically apply what you’ve learned over recent weeks, feel free to call into the store and we can talk you through it before your big day.

Next week we’ll look at energy bars and gels, which one’s to choose to best suit your needs, that’s part 7, honestly the end is in sight.

– Marc

About Marc:

Sports Science lecturer for 10 years at St Helens HE College.

2004 established The Endurance Coach LTD sports science and coaching business. Worked with British Cycling as physiology support 2008-2008. Previous Triathlon England Regional Academy Head Coach, North West.

In 2006 established Epic Events Management LTD. Now one of the largest event companies in the NW, organising a range of triathlon, swimming and cycling events. EPIC EVENTS also encompasses Montane Trail 26 and Petzl Night Runner events.

In 2010 established Montane Lakeland 50 & 100 LTD. This has now become the UKs leading ultra distance trail running event.

In 2010 established The Endurance Store triathlon, trail running and open water swimming store. Based in Appley Bridge, Wigan, we are the North West’s community store, organising and supporting local athletes and local events.

Check out the endurance store HERE

Endurance Store Logo

Race Day Nutrition (Part Five) – Marc Laithwaite

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Your body needs fluids for various functions. Body cells and tissues are filled with fluid, the nervous system requires fluid and the fluid component of your blood (known as plasma) is also affected by your drinking habits. Exercise leads to a loss of body fluids via sweating and breathing and this loss of fluid can eventually lead to what is commonly termed dehydration.

What happens when we drink?

When you put fluids into your stomach, they pass through the stomach wall into your blood vessels and effectively become plasma. As your blood stream can pretty much reach any part of your body, any tissue or any cell, this fluid can be transferred from the blood stream into the tissues or cells.

How does fluid actually pass from one place to another?

To get the fluid from your stomach into your blood stream or from your blood stream into tissue cells requires a process termed ‘osmosis’. Salt acts like a magnet drawing fluid towards it and the concentration of salt in your blood and tissues determines the shift of fluid around your body. When you take a drink of water it reaches your stomach and waits to pass through the wall into your blood stream. Your blood is saltier than the water in your stomach and due to the higher level of salt in the blood, the water is drawn from the stomach, through the wall and into the blood. This water effectively becomes blood plasma and travels around your body. If it finds muscle tissue, which has a higher salt concentration, the ‘magnetic’ pull of the salt within the muscle will draw the fluid from the blood into the muscle.

In simple terms, when something is dehydrated, it becomes salty. By becoming salty it’s magnetic or ‘osmotic’ pull increases in power and it attracts water towards it. That’s how fluid shift and hydration works within the body, that’s ‘osmosis’.

So how much should I drink?

Most guides will recommend somewhere between 1 – 1.5 litres per hour depending upon individual sweat rates, but it is unlikely that this amount can actually be absorbed when you are exercising. As each litre of fluid weight 1kg in weight, it is possible to calculate (very roughly) fluid loss by taking weight before and after and this will give you an estimation of how much you need to drink. This is a relatively simple process, go and ride or run for a couple of hours at the same intensity as your upcoming event and wear the same clothing etc. Weigh yourself before you go out, weigh yourself when you get back and then note how much fluid you drank. For example:

Weight beforehand: 80kg
Weight afterwards: 78.4kg
Weight lost: 1.6kg
Drink taken: 500ml (500g/0.5kg) – add this on
Actual weight lost: 2.1kg

*You should also take into account urination, if you stop for a pee during the session, that should be added to the loss!

Drinking too much is worse that not drinking enough:

For many years marathon runners were encourage to drink at every aid station and the key phrase was often “don’t wait until you’re thirsty, it’s too late then!” Unfortunately a few of those people died as a consequence due to a condition known as ‘hyponatremia’, which is excessive dilution of body salts. There needs to be some common sense applied to hydration. Your body tells you when you need fluid by making you feel thirsty and then you should drink however much you’ve lost. Your body operates very much like a water tank with an overflow system. Once the tank is full, any further fluid will be dispensed with by a visit to the toilet! It’s correct to say that urinating frequently and especially if the urine is clear, is not a sign of optimal hydration, it’s a sign you’re drinking too much.

Hyponatremia can be explained in this simple manner:

Take 1 medium sized bucket and add a teaspoon of salt and a pint of water to create a salt solution. Add another pint of pure water to the same bucket and you have now diluted the salt solution (it’s a bit weaker). Add another pint of pure water to the same bucket and dilute the salt even further. Keep going until the salt solution is so weak you can hardly even taste the salt. We said earlier in this article that salt acts like a magnet and attracts water towards it:

‘When you take a drink of water it reaches your stomach and waits to pass through the wall into your blood stream. Your blood is saltier than the water in your stomach and due to the higher level of salt in the blood, the water is drawn from the stomach, through the wall and into the blood’

What if you added so much water to your body that the blood wasn’t salty at all, it was diluted so much that it lost all its pulling power?

Salt intake:

Salt intake is a big question for many athletes and the basic guidelines tend to be relatively poor. Some people sweat more than others and the weather conditions will obviously have a large bearing upon both sweat and salt loss, but let’s examine the basics. Each litre of sweat contains 2.5-3.5g of salt depending upon the individual and how well acclimatised you are to hot conditions. IMPORTANT: Salt and sodium are 2 completely different things and we are interested in SODIUM’ and not ‘SALT’. Salt is 2 parts sodium and 3 parts chloride, so 2.5g of salt = 1g sodium / 1.5g chloride.

As a simple example, a tea spoon of salt = 6 grams. The 6 grams is made up of 2.4g sodium and 3.6g chloride.

Let’s presume that you are going to sweat 1 litre every hour (you need to do the calculation from taking weight before and after) and you sweat 2.5g SALT each litre, that means you sweat 1g SODIUM every hour.

Ok, so you’re sweating 2.5g SALT and 1g SODIUM every hour, so a tea spoon of salt (6 grams as explained above) would be enough for somewhere between 2 – 2.5 hours. Most sports drinks don’t have that much salt / sodium in them, so unless you take this into account, it’s likely in a long distance endurance event, your sodium levels will drop. The body does adapt by reducing the loss of sodium (it’s thins your sweat by reducing salt/sodium), but in hot conditions, your sodium intake needs to be addressed.

Remember the isotonic issue:

We said in last week’s blog that fluid intake is important when you are eating food, to ensure that the solution in your stomach is not too concentrated. For this reason, you need to consider fluid and food intake together. If you calculate that you are sweating 1 litre per hour and your planned intake of carbohydrate is 60g per hour, then that ‘technically’ gives you a 6% solution (1000ml / 60g = 6%). The timing of you fluid should be influenced by food intake, for example, if you eat half an energy bar, take fluid with it to dilute the solution. If you missed last week’s blog (part 4) which discussed carbohydrate solutions, click the nutrition link on the left hand blog menu and you’ll find it there.

Practical application of hydration strategies:

  1. If you’re urinating frequently and it’s clear, you may be drinking too much.
  2. Bloated stomach is one of the first signs of hyponatremia, coupled with vomiting liquid. Headaches are also a common symptom.
  3. Use electrolyte tablets in hot weather, but understand that hyponatremia is generated by too much fluid, as opposed to not enough salt. You should also check your energy bars or gels as many of them have salts included.
  4. Use thirst and urine colour as indicators of hydration status. Very dark, infrequent urine is a sign of dehydration.
  5. Weigh yourself before and after exercise as a simple guide to fluid loss, each litre of water weight 1kg, each millilitre weighs 1g.
  6. Try to incorporate food or energy intake as part of your hydration strategy and consider solution strength (isotonic)
  7. If you suffer from bloated stomach due to hyponatremia, don’t take more water, take more salt
  8. People with hyponatremia often don’t urinate, don’t confuse this with dehydration

– Marc

About Marc:

Sports Science lecturer for 10 years at St Helens HE College.

2004 established The Endurance Coach LTD sports science and coaching business. Worked with British Cycling as physiology support 2008-2008. Previous Triathlon England Regional Academy Head Coach, North West.

In 2006 established Epic Events Management LTD. Now one of the largest event companies in the NW, organising a range of triathlon, swimming and cycling events. EPIC EVENTS also encompasses Montane Trail 26 and Petzl Night Runner events.

In 2010 established Montane Lakeland 50 & 100 LTD. This has now become the UKs leading ultra distance trail running event.

In 2010 established The Endurance Store triathlon, trail running and open water swimming store. Based in Appley Bridge, Wigan, we are the North West’s community store, organising and supporting local athletes and local events.

Check out the endurance store HERE

Endurance Store Logo