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Some advice on pre race nutrition
Physiology (the science bit)
The two primary fuels that your muscles use while running a marathon
are carbohydrate and fat. Carbs are stored in the liver and in the
muscles as glycogen; fat is stored in the body too. When we run, our
bodies use both carbohydrate and fat as its energy source. Running
hard around the scenic Snowdonia course, athletes will derive
between 80 percent and 90 percent of their energy from carbohydrate,
most of it coming from their muscles' glycogen stores. As the miles
continue and your glycogen stores become progressively depleted, your
body will try to conserve what's left by burning more fat.
Athletes used to use more of their fat as an energy source. The downside of this is that the breakdown of fat requires more oxygen per calorie released than carbohydrate does, meaning that fat is a less efficient energy source. This makes us less efficient and hastens the point where we hit the 'wall'!!
Clever people have worked out that most people eating a normal diet can store no more than 2,000 calories of glycogen in their muscles. A mile of running burns roughly 100 calories. A marathon is 26.2 miles. Enter what for some people seems to be the entire point of becoming a Marathoner - carboloading. If you run, at most, a few miles a day in the few days before the marathon, and eat a high-carbohydrate diet, with 70 percent to 80 percent of calories from carbohydrates during that time, then endurance-trained muscles can stash away as much as another 800 calories, and the ‘Wall’ can get pushed beyond the finish line.
Carb loading has been proven to boost endurance performance.
Recent research suggests depletion/stripping of glycogen alongside hard training then consuming vast amounts of carbs and causing super compensation is not as effective as a well-conditioned athlete doing little more than consuming a higher quantity of carbohydrates in the three days before competition to receive full benefit.
Optimal carbohydrate loading can be achieved if approximately 600g of carbohydrate is consumed daily for two to three days. It is probably of little matter if the extra carbohydrate is consumed as simple (glucose) or complex (starch) carbohydrate. Most carbohydrates are digested quickly and enter the bloodstream via the intestine much the same as if glucose had been ingested. Replenishment rates are higher immediately after exercise due to increased insulin sensitivity. Carb loading can lead to weight gain because of extra water also being stored in the body, there is some evidence to suggest athletes load to a lesser degree and ingest a carbohydrate/electrolyte enriched drink during exercise to help maintain blood glucose and electrolyte balance (consuming carbohydrate during an event in the fully loaded state is overkill and produces no additional benefit).
According to Karen Reid, the English Institute of Sport nutritionist, The goal is to start the race with good glycogen reserves, so athletes should really concentrate on their food intake during the week before the race and normally they would taper their training, so they are not burning up their reserves. Ideally, they should rest 1-2 days before the race to really stock-up and increase their carbohydrate intake.
Carbohydrate is really important. Typically, athletes may need 10g of carbohydrate per kg of body weight. That’s an awful lot of carbohydrate which can’t always be sourced from potatoes, pasta and bread because they may be too bulky. Instead, athletes can look to more compact carbohydrate sources such as sweets and sugary drinks. For instance, 100g of jelly babies can give you 80g of carbohydrate the same as a portion of pasta!
The perfect race-day breakfast and when should athletes eat before racing?
Again, it’s a case of concentrating on carbohydrate intake, so having
a breakfast consisting of cereals and milk - pancakes are excellent -
or toast, bagels or malt loaf is advisable. Some athletes are able to
eat and then exercise within an hour and feel fine, but generally, I
would recommend eating two to three hours before a race.
During the race, taking on carbohydrate is crucial and sports drinks are obviously the most practical form. Some athletes may take glucose tablets, eat sweets or opt for one of the energy gels, but as with all of these techniques, it’s important that they are well-practiced and not suddenly introduced for the first time on race day.
After the marathon nutrition plays an important part in the recovery too, it can take several days for muscle damage to repair itself, so what an athlete eats and drinks after a Marathon is vitally important.
The first priority is hydration. Getting fluid into the cells quickly helps the body to replace any lost nutrients. After finishing the race, the body will need carbohydrate and protein, so a sandwich and a milkshake would be a real benefit within one hour of stopping exercise.
The worst thing an athlete can do is not eat anything and simply go to bed .They need to keep eating regularly to assist recovery.
EATING FOR THE MARATHON
A runner would need to eat 10gms carbohydrate per kg body mass in the three days leading up to the marathon to build good muscle glycogen (carbohydrate energy reserves).
For example a 70Kg athlete would require 700gms carbohydrate - see typical menu below:
Food / Carbohydrate (gms)
Breakfast
Glass Orange Juice (200mls) 20.0
Large bowl cereal (80gms) with semi-skimmed milk (250mls) 66.0
2 Slices Toast (extra thick bread) 45.0
Jam (4 teaspoons) 20.0
Lunch
2 rounds chicken & salad sandwiches (4 slices bread) 80.0
Fruit yoghurt 27.0
Large banana 20.0
Mid pm Snack
Malt loaf (2 slices) 46.0
2 pieces fresh fruit 20.0
Dinner
Large helping of spaghetti Bolognese (150gms raw weight spaghetti) + salad 125.0
Ice cream + fruit salad 70.0
Training Snacks and Drinks
100gms Jelly sweets 85.0
1 litre sports drink 70.0
Total
694.0gms
NB Compact sugary carbohydrate foods and drinks e.g. sports drinks and jelly sweets are a useful way of meeting the additional carbohydrate requirement, as they are less bulky and can be eaten closer to running.