Carbohydrate is the primary fuel for the muscles when you're racing at higher than 70 per cent maximal aerobic capacity. Photo: iStock
After running a couple of marathons, I wanted to find a new challenge – one that was big enough that I didn't know if I'd succeed. For me the English Channel was that challenge.
I had a few barriers: I hadn't done much swimming for 12 years, I had had seven joint operations and I had never swum in the dark, next to a boat or in water colder than 18 degrees.
So, I decided to focus on my strengths – nutrition and a strong mind. Over the seven months before the swim, I planned, refined and practised my nutrition plan – confident it would get me to France.
Some marathon swimmers, including John Van Wisse, actually have to put on weight before a big swim. Photo: Rebecca Hallas
You too may have set yourself a big goal. It could be the City to Surf, a marathon, or even moving from watching sport, to being back on the field.
When it comes to preparing nutritionally for these, a few lessons may help your journey.
A little bit is good – more is rarely better
Could you have been better prepared for the Melbourne Marathon last weekend? Photo: Luis Enrique Ascui
Just because something is good, doesn't mean you need truckloads to gain benefit – it can do the opposite. When we put too much of a good thing in, it can react badly. Any deficiency can cause problems but having too much of one thing displaces other nutrients, which ultimately can affect your performance or health.
Too much: For the English Channel, swimming in less than 16 degrees water, you don't sweat very much. So, you don't need to replace as much fluid. My requirements are only about 80ml per kilometre in this temperature, and covering about four kilometres an hour, my feeds were about 240ml every 45 minutes. Any more and I could have become nauseous.
For these swims (mine was close to 10 hours), cumulatively storing extra water could have dangerous effects. This condition – hyponatraemia – is common in recreational marathon runners.
Not enough: If you don't drink enough (more common in land events) you can become dehydrated. Everyone who is planning an endurance event should do a simple test, and repeat it a couple of times in the build-up to their event. Weigh yourself before a training session; this may be a one-hour run if you're training for a marathon.
Warm up a little, empty your bladder and weigh yourself. Run, swim or cycle at the speed you intend to race at for a period that will not require you to replace too much fluid. This may be 45 or 60 minutes. After the session, weigh yourself again. This gives you an approximate sweat rate and fluid requirement.
Carbohydrate: Mix it up
Carbohydrate is the primary fuel for the muscles when you're racing at higher than 70 per cent maximal aerobic capacity. If you're trying to go fast (or fast for you), you should consume enough carbohydrate to allow your muscles to do the work they need. There is good evidence for mixing up the types of carbohydrates for better performance and fewer gastric disturbances. This is because different types of carbohydrates are absorbed using different transport within the body (ie: maltodextrin, glucose, fructose, sucrose).
For slower athletes we aim to give about 30-60 grams of carbohydrate an hour, and for faster athletes up to 90g.
Depending on your genetics, metabolism system, body composition and previous training, an accredited sports dietitian will help you work out a target amount. Taking in enough carbohydrate doesn't mean you have to turn to the latest sports food. There are plenty of everyday foods that can double for fuel when you're competing.
When I'm doing a long swim I consume alternating drinks of Ovaltine, ginger cordial/sports powder mix, and the occasional flat Coke. The types of drinks rely on requirements, individual preference and availability.
If you feel you can't handle sports foods or drinks, it may be a case of training your digestive system. You'd be surprised at how quickly you will be able to adapt.
Use your heart in execution – and your head in planning
Once you get involved in a sport – whether open water swimming, marathon running, body building, triathlon or mountaineering – it's not uncommon for more experienced athletes to share their nutritional “secrets” with you. Beware of accepting though; combine their advice with science and you'll get a much better, and more predictable, result.
Smart people ask for help – from smart people
Get a plan from an accredited sports dietitian and work with them well before your event. You may be lucky enough to find a dietitian who is experienced with your sport (by either competing or working with other athletes) and up to date with the science that will help you perform – and keep you healthy on the way to your goal.
Get the big stuff right
Health is the first requirement for good performance, so before you empty your piggy bank on supplements and sports food, prioritise the basics of a healthy diet.
When you're exercising you need more nutrients than when you're not, but this doesn't mean you can eat whatever you want. What you eat while training is much more important than what you eat on the day of the event. You should look at achieving a good body composition early on, and again this is about balance.
For the English Channel many people need to put on weight to reduce the risk of hypothermia. Too little body fat may mean an unsuccessful swim but too much may mean you swim more slowly than your potential.
In weight-bearing sports, lower weight and body fat may be beneficial to performance, but losing too much may result in increased injury and illness throughout your training.
During training, some sessions should be well fuelled like you'd plan on race days, while others may be less fuelled to allow your body to adapt and prepare in case you're unable to race with good nutrition.
Practise, prepare and role play
It's important to begin early preparing nutritionally for a big event early. Most people think "she'll be right" – until it's not. It takes weeks for nutrition interventions to take effect. It's common to feel a little anxious before your event but making a last-minute change to your nutrition may not be a good idea.
As well as trialling your nutrition strategy, get acquainted with the nutrition available at and near your accommodation for your event. I always pack my nutrition before leaving. I learnt this the hard way when I ran the New York Marathon.
What containers do you need for nutrition? In the English Channel, my swim was cold, dark and rough. My support had pre-measured powder in individual bottles. The contents were transferred to a feeding shaker bottle and hot water added from a vacuum flask. The shaker bottle was on a yellow kickboard, so it floated easily in the water and could be seen in the dark. If your nutrition needs to be carried, what can you use to make this easier?
There are many things you cannot control in a big event – who shows up, for instance. Or the weather. Nutrition is the one thing you can plan. It's not the sole reason you'll succeed but it can be a main reason for failure.
In all, plan for the worst, hope for the best, and expect to learn something along the way.
Just run the Melbourne Marathon? Participated in the City to Surf, an ocean swim or triathlon? Jump on the comments and share your eating or training tip.
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