Posted on July 22, 2014 by Jenny Cromack

In my blog last week I talked about my marathon training. On Friday I ran my longest distance so far in my training plan – 17 miles. It felt pretty good (at the time!) and on pace for my long run……it felt good to get another long run under my belt. When I got back to the personal training studio at Marshall Court Lucy was there and laughed at me as I laid stretching on the mat feeling pretty broken…..she laughed, saying I bet she wished my personal training clients could see me as I moaned away!

On Sunday Lucy and I went to watch Kate and some of our clients run the Leeds 10k – it was a hot day and I’m sure many people felt the effects of the heat. As a nation I don’t think we are used to exercising in the heat (after all we’re not used to the sunshine are we?!) and so for the last couple of weeks I’ve really been encouraging my clients to stay hydrated. I think staying hydrated during exercise is something which many people neglect as they don’t really know how dehydration effects exercise performance.

Many people will often concentrate on drinking lots of water during a training session, but it’s important that you turn up to your training session, whether a personal training session, gym workout or exercise class, hydrated. After all, you wouldn’t get in your car with a small amount of coolant in the radiator and expect it not to overheat on a long journey….so think of your body this way too. If you start a training session just 2% dehydrated this can have a detrimental effect on your performance. An even scarier statistic is that only 5% dehydration can decrease your work capacity by 30% which will massively affect your progress to achieving your goals. Now imagine running something like a half marathon or marathon and think about how much harder that task the more and more dehydrated you become.

So, if for the past few weeks you’ve been struggling in your training sessions and don’t have the foggiest idea why…..then the likelihood is that you’ve been dehydrated so start drinking more!

You may be reading this and thinking…..Jenny, I’m not a nutter like you and go running for 17 miles, I lift weights so it doesn’t matter if I’m dehydrated. WRONG! Research has shown that only 1.5% dehydration can significantly impact 1 rep max performance on the bench press. Other studies have also shown that 3% dehydration can affect upper and lower body anaerobic power…..not good if you’re looking to get stronger and increase lean muscle mass. And, if you play sports which require cognitive-motor tasks such as golf, tennis, badminton, etc don’t think you can get away with being dehydrated either….. 1-2% dehydration levels can also affect performance as it affects accuracy of distances, shots, etc.

It’s quite scary how much a small level of dehydration can affect your performance and if you’re going to commit time to working out you want to get the most out of a session, not struggle half way through and begin to regret not being properly hydrated. So, to avoid dehydration affecting your workouts here are my top tips:

1. If you are training for an endurance event, weigh yourself before and after your ‘long’ training sessions (60mins plus) – each 1 pound lost is equivalent to 1 pint of water so this should tell you how much (extra) water you needed to drink during your training session.

2. Whatever time of day you are training make sure you are hydrated. If you train first thing in the morning then it is essential that you drink plenty the day before, especially if you have trained that day. If you train from lunch time onwards then you shouldn’t have any excuses. I would recommend that on a hot day you should have taken at least 1litre of fluid on board before a training session, if this is difficult first thing on a morning then a minimum of 500ml is a must.

3. During your training sessions you should take on board around 400-500ml of fluids every 20 minutes. Personally I prefer to take my fluids on board little and often, during this hot phase of weather I have been drinking every 2 miles (around 17 minutes) on my long runs and this has been working a treat! During my winter training I was drinking every 3 miles (around 25 mins) and drinking more frequently has made a huge difference to my training.

4. What should you drink? For anything less than 90 minutes of exercise you should be ok with water, however for anything longer than this (and potentially 60 minutes in the hot weather) you should look to take electrolytes on board and maybe some form of energy drink – I’m currently using Science in Sports ‘Go’ energy and electrolyte drinks on my long runs.

5. One of the biggest tips I can give you is don’t wait until you’re thirsty to drink….this already means you are dehydrated…..drink frequently throughout the day and you should avoid this. Keep a bottle of water on your desk, in your car, in your bag….strap it to your head with a straw for your mouth….whatever it takes, keep hydrated!!!

6. If your pee is dark in colour (straw-like) then you’re dehydrated……get drinking! Your urine should be clear or a very light yellow colour.

Remember that each and everyone of us is different…some people sweat more, some people sweat less…..you will need to experiment with what works for you but do not commit the cardinal sin of turning up to a training session dehydrated, it will not be a good session and probably result in you feeling rather frustrated that you haven’t been able to give it your all.

http://journals.lww.com/nsca-jscr/Fulltext/2012/11000/Effect_of_Acute_Mild_Dehydration_on.23.aspx

http://www.ncbi.nlm.nih.gov/pubmed/10198142

Saxton in Leeds

http://www.humankinetics.com/excerpts/excerpts/dehydration-and-its-effects-on-performance