With spring in the air and July almost behind us, now is the perfect opportunity for me to talk about one of my favourite topics. Running. I love running. Love it. When I read one of those motivational quotes about running it’s like someone has written down my most innermost thoughts on how I feel about running. Not only was the recent trip to Gold Coast to take part in the half marathon a winner in terms of discovering an awesome Spanish omelette (to which I made my own version), it has done wonders for my running mojo, which had been lacking in recent months thanks to a couple of injuries.
I’ve completed close to 8 marathons. Seven and 41/42.2 to be exact. It wasn’t an injury that stopped me from crossing the finishing line in Christchurch in 2010 in the coldest conditions I’d ever experienced during a race; it was dignity. My nutrition plan for the race was the undoing of an otherwise well executed run. I had a plan to eat my normal pre-race breakfast then take a carbohydrate gel every 30 minutes during the event. Carbohydrate is used to fuel the body during exercise and we have a storage capacity that is limited to around 90 minutes of moderate intensity activity before we run out (generally speaking). Sports nutrition guidelines recommend 30-60g of carbohydrate per hour (or 1g/kg body weight) in order to keep a steady supply of glucose in the blood stream the body can draw on for fuel. How much glucose that is tolerated is quite individual, though I had no fears of having any gastrointestinal (GI) issues – my claim to fame was a stomach of steel. I once consumed an entire mixing bowl of green gooseberries with no negative issues, and prior to other marathons managed to put away a simple carbohydrate feast of no less than five white buns with jam, an orange juice and a banana to hit the start line ready to run. Suffice to say, I backed myself, nutritionally speaking.
However a gel every half an hour combined with very little fluid throughout the run (due to the near-freezing temperatures) ended up being my undoing. To half way I felt absolutely fine. It wasn’t until around 27 km (what I like to term ‘no mans land’ in a marathon – too far in to back out, not far enough to be able to see the finish line) that I started experiencing a few stomach cramps. Nothing major, I thought – and soldiered on. I got to 31 km and, despite that I was beginning to feel a bit bloated, I took my gel on schedule. Thirty-four kilometres in was where it all unravelled. I was in need of a Portaloo, yet made the fatal error of thinking that I could hold it together to 42 km as it was only an ‘8k time trial’ to the end. How wrong I was. I’d never before experienced the ‘runs’ during a run and there was nothing I could do to stop the consequences of too many gels and not enough fluid. There was no bush to dive into and I’m no Paula Radcliffe; stopping and dealing to it on the race course was not an option. From 37-41 km I had an internal battle of whether to finish the run or not and in the end dignity stopped me from crossing the finish line. I pulled the pin at 41 km, jogged to the nearest public toilet to try and clean myself up before catching a lift back to the hotel for a much-needed shower.
If I learnt anything from the experience it was that relying too heavily on gels didn’t work for me in this instance. While muscle carbohydrate stores are certainly the limiting factor in endurance events, we are far better off trying to tap into an almost unlimited supply of energy and teach our body to burn more fat than carbohydrates, so we don’t have to rely so heavily on exogenous fuel sources. GI distress is one of the three main problems that clients come to see me about –and a lot of it is due to the overconsumption of carbohydrate gels or food when training or racing.
Very simply put, your body burns either fat or carbohydrate at a given intensity. At a lower intensity (at rest, walking, light aerobic activity), we burn proportionately more fat than carbohydrate. However as the intensity of the exercise increases, the fuel substrate shifts to burning predominantly more carbohydrate. Of course, across the spectrum of exercise intensity, you will likely burn both fat and carbohydrate, and the amount that you burn is influenced by a few factors. Three main ones are:
- Training history. Well trained athletes are able to burn more fat at a higher intensity than someone new to the world of endurance sport.
- What you eat before training. If you follow conventional sports nutrition principles then the standard high carbohydrate, moderate-to-low protein and low fat fare will provide you plenty of fuel to start your run with. When we digest carbohydrate, the body responds by releasing insulin, a hormone responsible for delivering that fuel to the working muscles. The only problem is that insulin is the fat storage hormone. Not a problem whilst your running (you’re very unlikely to be storing fat at this point!) However insulin switches off your ability to burn fat. Instead you are setting up an environment in the body whereby the reliance for carbohydrate is increased, yet (depending on the intensity) our body can’t absorb glucose at the rate at which we require it – increasing the risk of either GI issues (as I experienced) or of hitting the wall.
- Daily diet. Cereal for breakfast, sandwiches for lunch, pasta for dinner, and snacks of rice cakes, muesli bars and dried fruit has been standard fare for many an endurance athlete. Many of these foods are digested quickly by the body and produce the insulin response that I mentioned earlier. The subsequent fall in blood sugar levels as the insulin rapidly deals to the sugar that is released into the bloodstream can lead to low blood sugar levels and cravings for simple, easily digested carbohydrate foods that will drive your blood sugar levels up again – it’s an evolutionary response that was a useful survival mechanism back in ancestral times. The rollercoaster blood sugar response to carbohydrate impacts on your energy levels, mood, ability to concentrate and hunger. For a lot of people coming to see me, this eating pattern is often devoid of nutrients that endurance athletes are in need of: good quality fats, protein and non starchy carbohydrates that deliver micronutrients essential for repair and recovery. It’s not that carbohydrate for endurance training is not important; it’s the quality that matters. And the timing. If you’re eating in response to an energy crash it’s likely that you’re not reaching for a baked kumara to combat the blood sugar low.
I could go on. And I will, in future posts – the promise of spring and the upcoming marathon schedule gives me plenty of excuses to write about nutrition related to running (and other endurance sports). And, if the idea of going for a run makes you want to put a fork through your eye, stay tuned also –the principles associated with nutrition for sport apply to nutrition for life. In four words: just eat real food. And I’ll talk more about that in detail soon.