Do you know what foods you should eat before a workout or run? Or the perfect amount of water to drink to stay hydrated? Vhi Registered Dietitian & Performance Nutritionist, Evan Lynch, answers these questions and shares his expert tips for maximising performance during activity. 

Understanding how to fuel your body before exercise

If you take part in sports or exercise that require endurance, like cycling, swimming and running, you need to be tactical when deciding what to eat beforehand. Some of the perfectly healthy foods that we eat on a day-to-day basis could negatively impact your performance if you consume them before your workout. The closer in time you are to your workout, the more simplistic your food choices should be. This is because of digestion and absorption of food. Carbohydrates are going to digest (and therefore give you energy) faster than fats, protein or fibre. For example, let’s say you eat avocado and toast an hour before your run. This meal is a great source of fat and fibre, but it will take your body four to six hours to digest, absorb the nutrients and give you energy for your run. So having it only one hour before your run isn’t beneficial for that bout of exercise. It could also cause nausea or bowel issues as you run, as your body is trying to digest it!

The key takeaways here:

• You should focus on carbohydrates (and protein if you wish) before a workout, rather than fat and fibre. Carbohydrate options include things like a slice of toast with jam, a fruit smoothie or a granola bar.
• Timing is important so that your body can absorb the nutrients and give you the energy boost when you need it. 

Pre-exercise nutrition tips

Here are some guidelines and tips to follow:

• A good way to think of your pre-exercise nutrition is that you ‘pay’ for the energy or ‘fuel’ you’ll need to carry out your exercise with the two most recent meals you’ve had. 
• If you have the time, you should eat a meal of carbs (and protein if you like), 2-3 hours before you train or exercise. Ideally, you should aim for 1-2 grams of carbs per kg of your bodyweight. For example, if you’re taking part in the Vhi Women’s Mini Marathon and you weigh 80kg, you should consume about 80-160 grams of carbs in your 10.30am meal before the 12.30pm race. 

• You can add a ‘top-up’ of fuel about 30 minutes before the race if you like, so long as it’s something your body can very easily digest and absorb in that time, like a banana, dates or an energy gel. These things are simple sources of carbs and sugars and take roughly 30 minutes to digest, so you’re getting the energy just at the right time. 
• When it comes to early morning workouts and you won’t have 2-3 hours available beforehand to eat, or even 30 minutes for an easily digestible snack, you can ‘pay’ for your run the night before. Try adding an extra 50-60 grams of carbs to your diet before bed. This can be something easy like a bowl of cereal, a rice pudding, or a bagel. 
• Pancakes are a brilliant pre-run meal. So is a bagel or toast with jam, waffles or a bowl of cereal.
• This one can be controversial, but I wouldn't recommend a bowl of porridge before a run! Because of the digestion and absorption discussed, I would favour a light cereal instead. 
• If you’re someone with a particularly sensitive stomach, some kind of sports drink or juice 30 minutes before you start should be enough to fuel you for a 5-10k run or 45–60-minute workout.  

Pre-exercise hydration tips

When it comes to hydration, there are two things we should keep in mind:

1. If you drink too much water before a workout or run, acid reflux and nausea are the most likely outcome. If your tummy is full of liquid when you run, it’s going to make you feel uncomfortable. The magic number here is 5mls of water per kilo of bodyweight, per 90 minutes. What this means is, if you’re 80kg in weight, and you slowly sip on 400mls of water over a 90-minute period before your race, you’ll start your race optimally hydrated. 
2. We also consider the sodium levels in our blood. If you drink too much water, your sodium levels become too diluted, which causes your kidneys to release anti-diuretic hormones, which make us need to pee! Keeping to the right amount of water for your weight and pre-run timeframe will avoid this. Isotonic water and electrolyte tablets can be used for hydration to replace minerals like sodium that you lose when you sweat. 

Figuring out the precise foods that best fuel and energise you before a run can take a bit of practice, but following my tips above will have you on the right track. Pay attention to your performance when you try certain foods, and you’ll soon know what feels best for your body. And remember, your healthcare provider or dietitian can guide you if you’re unsure. 

Hopefully, you now feel confident in fuelling your body as best you can before a run, race or workout. It’s important to also be mindful of your post-exercise nutrition and hydration. Have a look at my blog, ‘Your guide to eating after exercise’, for insights and tips. 

This content is for information purposes only and is not intended or implied to be a substitute for professional medical advice, diagnosis, or treatment. Always seek advice from your GP or an appropriate medical professional if you have concerns about your health, or before commencing a new healthcare regime. If you believe that you are experiencing a medical emergency call 999 / 112 or seek emergency assistance immediately.