Archives for category: Hydration

Hi there,

Training and competing pose challenges on the body with regards fuel stores, hydration and regulating body temperature. With a few exceptions, very few sports events put as much stress on the body as competing in a marathon. Here are some tips that will help you prepare and recover for your upcoming marathon.

Week Before

1- Rest and Sleep

While not necessarily a nutrition tip, it is vital to rest and sleep well in the week before your event. You have all the hard training done, although you might have a few light sessions planned. Getting at least 8 hours sleep every night will allow your body to recover and be fully prepared for the task ahead.

2- Carb Loading

We have two fuel sources that our body uses during exercise – fat and carbohydrate. At lower exercise intensities (resting, walking, jogging), our bodies prefer to use fat as we have large quantities stored in our bodies.

At higher exercise intensities (hard running), our bodies prefer to use carbohydrate stored in our muscles and liver as it can access it and release the energy more quickly. However, a problem with this is that we have the ability to store only small amounts of carbohydrate in our bodies (300-500g). If you’re trying to perform a personal best (i.e. exercising at a high intensity), there is a possibility of running out of carbohydrate (i.e. hitting the wall, bonking) later in the race. When this happens you will have to slow down, and you might feel dizzy, faint or disorientated.

In order to prevent this happening, you will have to carb-load. Carb-loading involves eating larger than normal amounts of carbohydrate in our to max out our bodies ability to store carbohydrate. This should allow you to run faster for longer.

The recommendations say that you should be eating between 8-12g per kg of body weight. As an example, for a 70kg person, this would mean eating between 560 – 840g of carbohydrate. This is very difficult to do eating a healthy diet.

In order to achieve this, you will need to cut back on eating protein, vegetables, fat and fibrous starchy carbohydrates (e.g. porridge oats, brown pasta and rice). Normally it is a beneficial to eat these types of foods, but they may stifle your appetite when carb-loading, making it more difficult to reach your carbohydrate targets.

You will need to eat more sugary types of carbohydrates (e.g. sugary breakfast cereals, fruit juices, jam, snack bars, sports drinks, smoothies, white flour based foods (pancakes)) and low fibre starches (e.g. white rice, white pasta, white bread).

Eating these types of foods allow you to over-eat and hit your targets. A word of warning – only do this when preparing for a marathon, when doing a long run (18+ miles) or practicing your race nutrition. If you do this on a regular basis, it will more than likely lead to you increasing your body fat.

Finally, I would recommend doing this 2 days before your race, giving your body time to digest and store carbohydrates and get rid of waste. You can then eat a normal diet the day before.

3- Hydration

When your body stores carbohydrates, it does so with water. If you’re eating and storing larger than normal amounts of carbohydrates, you are drawing extra water into your muscle and liver. As a result, you may need to increase your fluid intake. Keep a close eye on your hydration levels.

  • Thirst may increase.
  • Urine may be darker in colour.
  • You may only pass a small amount of urine.

If you experience any of these symptoms then drink a pint on water immediately and then drink 200ml every 20-30 mins until the symptoms above are improved. It is also best to drink with a meal or snack as your body will absorb fluid more efficiently.

Morning of and During Race

4- Breakfast

Marathons normally start early in the morning. Try and eat a breakfast 2-3 hours before the race start. This is highly individual but ensure you get some carbohydrates (e.g. porridge) and a small amount of protein (e.g. boiled egg) at a minimum. Continue hydrating (but not too much).

5- Eating during race

After the first hour of your race, you should be aiming to consume 30-60g carbohydrate per hour during the race to keep your blood sugar levels high, continuing to fuel your run. A typical sports gel will contain 30g of carbohydrate. So will 500ml of a typical sports drink. However, consuming these in large quantities can cause stomach ache, pain and diarrhea in some people. It would be a good idea to vary carbohydrate sources (e.g. ripe banana, energy bar, snack bars) to prevent these uncomfortable side effects.

6-  Hydration

How much you sweat during a race will determine how much fluid you drink. The environmental conditions and the course will play a role in this. You will sweat more in warm, humid condition and/or on a hilly course. Conversely, you will sweat less on a cold, windy, rainy day and/or a flatter course. Some level of dehydration is OK and may be beneficial as you will be lighter and will expend slightly less energy. This is typically up to 2% of body weight. Anything over this may impair performance. It is very difficult to give a recommendation of how much fluid you should drink, As well as the factors listed above, everyone has slightly different sweat rates. At a rough estimate, you should be drinking 400-500ml per hour.

Be careful of drinking too much fluids, as this could mean an early finish to your day!

After Race

7- Immediately after race

Within 0-60 mins of your race finish, you should try to consume a recovery shake containing carbohydrate and protein or if not available, 1-2 bottles of sports drinks. This will help to kick-start refuelling.

8- 1-3 hours after race

You should aim to eat a big meal 1-3 hours after a race. This should contain a large portion of carbohydrates, protein and vegetables. The carbohydrates will continue to refuel the body, protein will help to repair and rebuild muscle and vegetables will contain vitamins and minerals which will help your immune system.

9- 72 hours after race

Continue to eat breakfasts, lunches and dinners containing protein, carbohydrate and vegetables up to 72 hours after the race. One of the big complaints by novice marathon runners is DOMS (Delayed Onset Muscle Soreness). DOMS is muscle soreness which appears two days after the race. By eating regular doses of protein with your meals, this will help with repairing muscle and help to prevent DOMS or at a minimum diminish the muscle soreness.

10- Rehydration

If you have a portable scales then bring it with you to the race. Try and weight yourself immediately before and immediately after the race. You should have lost weight – if you have gained weight then this means you drank too much fluid.

If you lost weight, get the difference and multiply by 1.5. For example, if you lost 3kg then the amount of fluid you need to drink to fully re-hydrate is 4.5L (3 x 1.5). You don’t need to drink all of this immediately, but over the 24 hours after the race.

Word of warning – beer and alcohol don’t count towards rehydration. Drinking large quantities after a race will cause further dehydration and will delay recovery.

I would like to wish you all the best in your upcoming marathon. If you follow the steps above I think you will have an enjoyable race and hopefully hit a P.B.. If you have any questions, please email me at: kevin@metabolise.ie

Yours in sport,

Kevin

Another important factor for performance, especially in warm conditions, is hydration. Severe dehydration will have a negative impact on performance, causing you to fatigue and slow down. We can generally tolerate a certain level of dehydration (a 2-3% reduction in body weight), but anything greater than this will have a negative impact.

 

What is the optimal drinking strategy? There is a high level of individual variation in how much we sweat during exercise. We all differ based on training status, hydration status, ambient weather conditions, terrain, clothing etc. The best strategy is to measure your own individual sweat rate. This is relatively easy to do.  For your convenience, I have created a sweat rate and re-hydration calculator on my website at the following link:

 

http://www.metabolise.ie/?tools.html?tools/sweat_rate.html

 

To calculate your sweat rate, you will need to measure the following:

 

  • Weigh yourself (preferably nude) before training/competition.
  • Weigh yourself (preferably nude) after training/competition and after towelling down.
  • Measure the amount of fluid consumed.
  • Estimate any urination between before and after weigh in.
  • Duration of training session or competition.

 

With this information at hand, you can calculate your sweat rate.  Ideally, you will exercise at race pace for one hour (possibly shorter for swimming). This will allow you to estimate your average sweat loss. You can do this for the three different disciplines, as it is likely you will sweat at different rates depending on the type of activity you’re doing. Ideally, you would perform this test during  a warm-up race to make the figure as realistic as possible.

 

With this information at hand, you can then calculate your ideal rehydration rate. The calculator allows you to factor in an acceptable level of dehydration. This is set at 2%, which is the maximum accepted weight loss without a negative effect on performance.

 

If you want to take it to a professional level, determine your sweat rates in different environmental conditions (cold, moderate, hot weather) so that regardless of the weather on the day, you will know what your ideal hydration strategy is for those conditions.

 

One important consideration with hydration is hyponotraemia , which is a potentially serious medical condition. Hyponotraemia is  caused by consuming too much fluid, resulting in a change in the composition of blood plasma and potentially fatal knock on effects (e.g. swelling of the brain). This generally occurs for beginners or slow competitors who consume excess fluids (i.e. drink more fluid than they lose through sweating) during a triathlon. This is one reason why it is a good idea to measure your sweat rate and have a hydration plan in place. As well as keeping you hydrated, it will prevent you from developing hyponotraemia.

 

One last thing to mention is caffeine, which has the potential to enhance your performance.  Caffeine works by altering your perception of how hard you’re working. I can testify to the power of caffeine as it has helped me finish a long hard ride on more than one occasion.

 

Caffeine can be consumed in a number of ways – by taking caffeine tablets in measured doses, by eating a gel which contains caffeine or by drinking coffee or Coke. One point to be aware of is that if you are a habitual coffee drinker than you may not get this performance enhancing effect. The best way to ensure that you get a boost is to stop consuming coffee or caffeine containing products 4-5 days before your event. This “wash-out” period will allow you to get the best effect from caffeine when you take it during an event. As with all nutrition strategies, experiment in training to see if this is right for you.