Carbohydrate loading for a half marathon

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The Central Coast half marathon (21.1km) coming up on Sunday the 25th of November. During a half marathon, there is a high reliance on the aerobic energy system however, efforts are also required for hills and/or sprint finishes so being fuelled to push through the 21.1km event will require both effective physical and nutritional strategies.

This blog will focus on a general carbohydrate (CHO) loading protocol which is suitable to the half marathon, however it is important to note it is not beneficial to those participating in the 10km fun run. Studies have shown that CHO loading for events over >90 minutes in duration can increase capacity by 20% by expanding time to fatigue, extending the duration of steady state exercise and increase performance by 2-3% by enhancing fuel availability.

Increasing stored muscle fuel (CHO) through dietary strategies in the 24 hours prior to an event can positively impact what can limit athletes in a race including fluid balance, availability of CHO for fuel and lactate accumulation from anaerobic efforts. This is because the body can better utilise CHO that is already stored in the muscle prior to an event.

When CHO loading, nutrient dense/CHO rich foods (such as wholegrain breads and cereals, starchy vegetables, fruit and dairy) should be prioritised to meet fuel demands, however there may need to be additional carbohydrates included (sports drinks, energy gels, ‘extra’ foods) to improve performance in in the lead up or during competition.

Depending on gender, current lean muscle mass, how trained the athlete is and current CHO intake will determine an individual’s CHO requirement for a load (usually between 6-10g/kg/bwt). As an example, a 70kg male may require 420-700g of CHO, 24 hours prior to a distance running event. While this is a good opportunity for athletes to enjoy some ‘extra’ energy dense foods to meet these high requirements, it is essential that nutritious foods are also consumed (don’t just ‘garbage’ load).

Although low body fat stores are desired by distance runners in an attempt to benefit performance, severe energy and nutrient restrictions can lead to fatigue, nutritional deficiencies, hormonal imbalances and bone injuries. The loading phase is only one element to preparing for a half marathon, as strategies the morning of, during, and after are also essential to ensure athletes maintain pace and cognition, enhance training adaptations and prevent fatigue. To put a tailored plan to suit your training goals and race requirements book in with a dietitian to keep you lean, healthy and ready to run!

Example Carbohydrate Loading Plan

Based on a 32-year-old female, who weighs 56kg and is a moderately trained athlete, aiming to complete a half marathon in 2 hours (average finishing time of last year’s event).

THE DAY (24 HOURS) BEFORE THE EVENT

Energy Intake 200kg/kg/bwt = ~11,200kJ/day Carbohydrate Intake 6g/kg/bwt = ~336g/day

Breakfast
2 cups Kellogg’s Rice Bubbles
2 tsp white sugar
1 cup light milk
1 medium banana

Snack 1
1 cup fruit salad in juice
2 tsp Moccona coffee
¾ cup boiling water
30mL light milk

Snack 2
2 large boiled eggs

Lunch
¾ cup penne pasta
1 large piece butternut pumpkin diced and baked
4 slices ham
½ cup traditional Bolognese sauce
40g baby spinach (diced and stirred through pasta)
¼ cup light shredded cheese

Snack 3
350mL of lemonade
1 thick plain rice cake
1tbsp honey

Snack 4
30g raw almonds

Dinner
¾ cup couscous
½ cup steamed corn
1 medium carrot, diced and steamed
125g chicken breast fried in 1tbsp extra virgin olive oil
1 tbsp soy sauce
¼ medium avocado

Supper
1 cup jelly

Book an appointment with one of our Dietitian’s by calling (02) 4356 2588 or book online via the button below.

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Thanks to Coast Sport Dietitian Ali for preparing this blog. You can find out more about Ali here.