Preparing for an Ironman triathlon is a monumental task, testing the limits of endurance with a 2.4-mile swim, 112-mile bike ride, and a full marathon (26.2 miles) completed back-to-back. Nutrition during race week is paramount in ensuring your body is ready for the challenge. A well-thought-out plan focusing on macronutrients, micronutrients, hydration, and electrolytes will not only maximise performance but also prevent fatigue, muscle cramps, and the dreaded ‘bonk’.
In this blog, we’ll dive into the most up-to-date research on race week nutrition, discussing the essential role of macronutrients, micronutrients, electrolytes, and hydration. We’ll provide a mix of plant-based and meat-based meal ideas, ensuring all athletes can optimise their diet as they approach the race day.
The Importance of Macronutrients in Race Week
Carbohydrates: The Key to Energy Stores
Carbohydrates are your body’s primary source of fuel during endurance events. During the final week leading up to race day, carbohydrate loading is vital for maximising glycogen stores in your muscles and liver. Glycogen is the stored form of glucose and is crucial for sustaining energy throughout the Ironman.
Research consistently backs carbohydrate loading as a means to improve endurance performance. According to a review published in Sports Medicine, athletes should aim to consume 7-12 grams of carbohydrates per kilogram of body weight during the 24-48 hours leading up to the race to maximise glycogen stores (Burke, 2015). For an athlete weighing 70 kg (154 lbs), this translates to between 490 and 840 grams of carbohydrates per day.
Carbohydrate Loading Strategy:
• 5-7 Days Before the Race: Begin tapering your training while maintaining a balanced diet, with carbohydrates making up about 50-60% of your total daily calories.
• 2-3 Days Before the Race: Increase your carbohydrate intake to 70-75% of total calories, focusing on low-fibre, easily digestible carbohydrates such as white rice, pasta, white bread, and low-fibre cereals.
Protein: Supporting Muscle Repair
Protein is essential for muscle recovery, especially during the tapering phase in the final week before the race. While carbohydrates are the main focus, neglecting protein can lead to muscle breakdown. Current guidelines suggest consuming between 1.2 and 2.0 grams of protein per kilogram of body weight each day (Phillips & Van Loon, 2011). This should remain consistent throughout race week.
Meat-Based Protein Sources:
Chicken, turkey, lean beef, and fish such as salmon or cod.
Plant-Based Protein Sources:
Tofu, tempeh, lentils, chickpeas, and quinoa.
Fats: A Secondary Fuel Source
Although fat is metabolised more slowly than carbohydrates, it is a useful energy source during long endurance events, particularly once glycogen stores are depleted. Endurance athletes should maintain moderate fat intake (20-30% of daily calories) and opt for healthy fats such as those found in avocados, nuts, seeds, and olive oil. However, avoid consuming excessive amounts of fat immediately before the race, as it can slow digestion and potentially cause gastrointestinal discomfort.
Micronutrients: The Essential Catalysts for Performance
Micronutrients are needed in smaller quantities than macronutrients, but they play an equally vital role in supporting energy production, muscle function, and immune health. Here’s a breakdown of the most important vitamins and minerals to focus on during race week:
1. Iron
Iron is essential for transporting oxygen in the blood, which is especially important during aerobic activities such as swimming, cycling, and running. Endurance athletes, particularly women, are more prone to iron deficiency, which can result in fatigue, decreased performance, and impaired recovery.
Meat-Based Iron Sources:
Red meat, poultry, and seafood.
Plant-Based Iron Sources:
Lentils, spinach, fortified cereals, and tofu. Note that plant-based iron is less readily absorbed, so pairing these foods with vitamin C-rich items, such as oranges or bell peppers, can enhance absorption.
• Recommended Intake: 18 mg/day for women and 8 mg/day for men, though athletes may require more depending on their training load.
2. Magnesium
Magnesium supports muscle contraction, relaxation, and energy metabolism, all of which are critical in a long-distance race. A deficiency can lead to muscle cramps and increased fatigue, so it’s important to ensure adequate intake through diet or supplementation.
Sources:
Almonds, seeds, whole grains, leafy greens, and legumes.
• Recommended Intake: 400-420 mg/day for men and 310-320 mg/day for women.
3. Calcium
Calcium is crucial for muscle function, including contraction and relaxation, as well as for maintaining strong bones. Given the high-impact nature of running, sufficient calcium intake is essential for preventing stress fractures and other bone injuries.
Meat-Based Calcium Sources:
Dairy products such as milk, cheese, and yoghurt.
Plant-Based Calcium Sources:
Fortified plant milks, tofu, kale, and broccoli.
• Recommended Intake: 1000 mg/day for adults, 1200 mg/day for women over 50.
4. Vitamin D
Vitamin D helps with calcium absorption and is also vital for immune function and muscle recovery. Deficiency in this vitamin can impair muscle strength, which is critical in an endurance race like Ironman.
Sources:
Sunlight exposure, fortified foods, fatty fish (such as salmon or mackerel), and egg yolks. Plant-based athletes may need to consider fortified products or supplements.
• Recommended Intake: 600 IU/day, although higher doses may be necessary for those with limited sun exposure.
5. Sodium and Potassium (Electrolytes)
Electrolytes help regulate fluid balance, nerve function, and muscle contractions. Sodium and potassium are particularly important, as these are the key electrolytes lost through sweat during endurance events. Ensuring proper replenishment is essential to prevent dehydration and muscle cramps.
Sources of Sodium:
Table salt, sports drinks, salted pretzels.
Sources of Potassium:
Bananas, potatoes, spinach, and avocados.
• Recommended Intake: Athletes may need 500-1,000 mg of sodium per hour during the race, depending on sweat rate, while potassium intake should aim for around 4,700 mg per day.
Hydration: The Foundation of Endurance
Dehydration as small as 2% of body weight can drastically affect endurance performance. Hydration strategies in race week should focus on ensuring athletes begin the race well-hydrated and maintain fluid balance throughout the event. However, overhydration can lead to hyponatremia (low sodium levels), which can be dangerous.
Race Week Hydration Guidelines:
• 5-7 Days Before the Race: Gradually increase fluid intake, drinking to thirst, and incorporating electrolyte-rich drinks, particularly if racing in hot conditions.
• 48-72 Hours Pre-Race: Focus on “hyper-hydration” by consuming fluids with added electrolytes. A study in The Journal of Strength and Conditioning Research suggests that sodium-rich drinks during this phase can help retain water and reduce the risk of dehydration (Shirreffs, 2005).
• Morning of the Race: Drink 500-700 ml of water 2-3 hours before the race, allowing time for absorption. Sip on an electrolyte drink in the final hour before the race starts.
Electrolytes During the Race
During the Ironman, athletes lose substantial amounts of electrolytes through sweat. Replenishing sodium, potassium, calcium, and magnesium is crucial to avoid cramps, dehydration, and fatigue. A good rule of thumb is to consume 400-700 mg of sodium per hour during the race, depending on your personal sweat rate.
Meal Ideas for Race Week and Race Day
Race Week (5-7 Days Before the Event)
• Breakfast: Porridge made with oats, almond butter, honey, banana, and chia seeds. Add a glass of orange juice for vitamin C to aid iron absorption.
• Lunch: Grilled chicken or tofu salad with mixed greens, quinoa, avocado, and a lemon-tahini dressing.
• Snack: Greek yoghurt or coconut-based yoghurt with mixed berries and a handful of almonds.
• Dinner: Baked salmon or tempeh with sweet potatoes, steamed broccoli, and a side of brown rice.
Carbohydrate Loading Days (2-3 Days Before the Race)
• Breakfast: Pancakes with maple syrup, scrambled eggs or scrambled tofu, and a glass of apple juice.
• Lunch: Turkey or plant-based sandwich on white bread with cucumber and lettuce. Add a side of pretzels or rice cakes.
• Snack: Smoothie with low-fibre fruits (like mango and banana), almond milk, and a scoop of protein powder.
• Dinner: Pasta with marinara sauce, grilled chicken or tofu, and a side of garlic bread.
Night Before the Race
• Dinner: Simple pasta with marinara sauce, a small portion of lean protein (chicken, turkey, or tofu), and a white bread roll. Avoid high-fat and high-fibre foods to reduce digestive stress on race day.
Race Morning
• 3-4 Hours Pre-Race: A bagel with peanut butter and honey, a banana, and a sports drink. This meal provides easy-to-digest carbs and a small amount of fat for sustained energy.
• 1 Hour Pre-Race: A small energy gel or half a banana, accompanied by sips of an electrolyte drink.
Hydration and Fueling During the Race
During the race, athletes should aim to consume 60-90 grams of carbohydrates per hour from a mix of sources such as energy gels, bars, and sports drinks to maintain blood glucose levels and avoid glycogen depletion. Regularly hydrate with water and electrolyte drinks to maintain fluid balance.
Conclusion
The week leading up to an Ironman is critical for ensuring your body is fuelled, hydrated, and ready for peak performance. Carbohydrate loading, maintaining protein intake, and ensuring moderate fat consumption will support energy needs. Adequate hydration and electrolyte balance are equally vital to help you avoid fatigue and cramping during the race.
By planning your race week nutrition carefully, whether on a plant-based or meat-based diet, you can set yourself up for success and cross the finish line feeling strong.
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