Firstly, do you have any expert tips you often tell open water swimmers?

I think my main tip will always be about strategy, whether that’s hydration, nutrition or race pace strategy, treat that as importantly as anything else you do as part of that training. It’s not all about just swimming. The biggest mistake I see across the board, whether that’s swimming, running or cycling, is people who have a race strategy that they have never tried before. In general they are always the ones that fail. A swim can be won or lost, can be enjoyed or spoilt, based upon poor preparation. I think the key really is that once you’ve decided on a strategy what you should be doing is trailing that strategy in training so that you know it works for you.

Do you find that a person's mental state during swimming, or during intense exercise, can be affected by their diet?

Yes is the answer to that. We know that nutrition is closely linked with mood and we know that there are certain foods that we eat which have a direct impact on what we call ‘happy hormones’. The one that we’re most interested in is dopamine which gives us this feel good factor.

We all have our likes and dislikes when it comes to food and we also have our treats. Often those treats are not only physiological in their effect, in that they provide calories, but they also provide a psychological and therefore mental and emotional health benefit. What we know is that for swimmers who are calorie depleted, it does affect your mood. When a person is hungry it causes a drop in mood. Therefore making sure that you’ve had optimum nutrition in terms of quantity and quality is important to make sure that you really feel the positive impacts of exercise, of swimming itself. Nutrition is intimately linked to mood without any shadow of a doubt.

We’ve all heard the cliché of don’t eat an hour before swimming, is there any truth in this?

What you shouldn’t do is eat a big meal prior to swimming, to be honest with you that’s sound advice for just about any exercise. At the very least it just creates nausea, gastrointestinal discomfort or bloating. The other thing to think about is that when you eat food you redirect blood flow to the centre of the body, particularly to the stomach and intestines. So if you are directing blood flow towards those areas, this can limit the blood flow going to the muscles. So by eating a big meal before you swim you could be compromising the quality of your training session. The original advice was actually based on big meals causing cramp and being linked or associated with drowning. If you are a proficient swimmer that’s less likely, but for me the advice still stands because it’s based on performance not upon lifesaving. Unlike most dogma there’s some good evidence to support it but what we do is support it with the wrong evidence. We support it with the evidence that you’ll get a stitch and you’ll drown but for most proficient swimmers that simply won’t occur. But it will compromise the quality of your session.

That said, obviously we lead very busy lives and if you find yourself coming into swimming after work, for example, often people will arrive dehydrated and with depleted energy stores. What swimmers should do is try to get the best performance out of their sessions by making sure that they're optimally hydrated and calorie loaded. Now there’s two ways of doing that, one is to top up your energy stores by small amounts regularly throughout the day but equally there is a value in snacking prior to swimming if you are doing it in a slightly depleted state.

You touched on hydration, are there any special ways swimmers can stay optimally hydrated?

When swimming the gut’s uptake rate is relatively compromised for a variety of reasons so if you overload the gut you are going to cause the same sort of discomfort and the same sort of problems. Again it works best with little and often. There’s lovely evidence that demonstrates that the inclusion of electrolytes and of sugars in fluid improves the uptake. So to some extent what you can do is kill two birds with one stone. In open water swimming drinking fluids that contain calories is probably the easiest way to top up energy and hydration levels. In general, though I hate the term ‘sports drinks’, carbohydrate-based drinks can be quite valuable.

On that note, energy gels seem to be getting increasingly popular, would you recommend them on the same basis?

I always put energy gels in the marmite category: people either love them or they hate them. I think it probably comes back to the original point about trialling. You have to find your own strategy. Gels can be great but remember gels don’t rehydrate so you do have to have a rehydration strategy with them, they do contain very high levels of sugars so for some people they can cause significantly gastrointestinal discomfort. It’s all about finding if they work for you but again the classic endurance faux pas is to consume far too many. Some of my best nutrition stories are based on marathon runners with 26 gels strapped around their waist like a hand grenade belt.

I do use them myself - I use them sparingly. I guess the one issue here is around what we would call satiety, around that feeling that you are full. What you often find with high sugar based products (so gels, sport tablets etcetera) is that they don’t tend to drive satiety so you can end up feeling hungry. Again you just need to think about what you are taking and when you take it.

Finally, does outdoor swimming affect the body differently from swimming in heated pool?

With open winter swimming the water temperature tends to be a lot colder. So when you’re going into cold open water swimming picking up the pace a bit can actually help you to thermoregulate a bit better because it provides a bit of extra warmth. If you get cold, the bodies response is to shiver and what we call this is shivering thermogenesis. We actually create an awful amount of heat through shivering. It’s a really important response when we’re cold. Shivering can also actually improve the rate of metabolism, so energy turnover can increase by up to tenfold.

Cold open water swimming tends to increase calorie expenditure at a faster pace than it would in a pool environment. In terms of weight management that’s why cold open water swimming is actually quite a nice environment because for the same exercise load you can increase calorie turnover. What you have to remember is that because if you are colder you are going to deplete stores of energy quicker. Interestingly, shivering thermogenesis is almost 100% carbohydrate based so you tend to find that for swimming in open water it is much more important to consume carbohydrates than it is for warm indoor swimming.

In 2017 Greg took part in our Solent swim from Portsmouth to the Isle of Wight as part of his '50 swims at 50' challenge. Find out about our popular Solent swim here.

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