Carbohydrates have stirred up strong feelings for years. For some they’re the foundation of energy; for others, something you “should avoid”. In practice, for physically active people – especially those who train hard, as in CrossFit, HYROX, endurance running or cycling – carbohydrates are first and foremost fuel.
Why do active people need carbohydrates?
During intense exercise your body readily uses glucose and muscle glycogen – the stored form of carbohydrate kept in your muscles and liver. This matters most during interval-based, explosive, high-power efforts – which is exactly what CrossFit workouts, functional training and HYROX races often look like.
Research shows that carbohydrate availability affects your ability to sustain intensity, delay fatigue and maintain the quality of work during a session. In other words, a well “fuelled” body has a better chance of performing efficiently.
This matters, because many active people eat too few carbohydrates, mistaking cutting calories for eating better. Yet not getting enough fuel can drag down not only your performance but also how you feel day to day.
Carbohydrates and recovery – an often overlooked piece
The role of carbohydrates doesn’t end with the last set of your workout or the finish line of a race. After hard exercise your body needs to rebuild glycogen, and carbohydrates are essential for that.
Studies by Ivy and colleagues show that eating them after training supports faster glycogen resynthesis – in other words, restocking your energy stores. In practice this can mean feeling less tired the next day, being readier for your next session and recovering more efficiently.
This isn’t only relevant if you compete. Even with 3–4 sessions a week, proper recovery decides whether you’re building fitness or piling up fatigue.
Carbohydrate quality matters
It’s not just how many carbohydrates you eat that counts, but where they come from. Your everyday diet should be built on foods that provide not only energy but also fibre, vitamins and a feeling of fullness. Rice, potatoes, grains, porridge oats, good-quality bread, fruit and pulses all fit this model well.
Around training, things can look a little different. Here, foods that are easier to digest and deliver energy faster sometimes work better – for example fruit, rice, bread or rice cakes.
And this is a key point: there are no “good” and “bad” carbohydrates out of context. There are simply different tools with different uses.
Do simple carbohydrates make sense after training?
They’re often demonised, yet after hard exercise they can be very practical.
Faster-absorbed foods can support glycogen replenishment, especially if your next session isn’t far away. In that context their role is functional, not “unhealthy”.
It’s a good example of how in sports nutrition what matters isn’t only what’s in a food, but also when you eat it.
What about endurance training – running, cycling or triathlon?
In endurance sports the role of carbohydrates is even more obvious. The longer the effort lasts, the more glycogen availability and carbohydrate intake during exercise matter.
During longer runs, rides or triathlon sessions your body gradually depletes its glycogen stores. When they run too low, your pace starts to drop, the effort feels harder, and many athletes know this moment as the classic “hitting the wall”.
That’s why carbohydrate strategies are so important in endurance sports. Research shows that taking in carbohydrates during long exercise can improve endurance, help you hold your pace and delay fatigue. Depending on how long the effort lasts, recommendations are usually around 30–60 g of carbohydrate per hour, and for very long sessions even more.
In practice that could mean energy gels, carbohydrate drinks, bananas or other well-tolerated sources of fuel.
Carbohydrates also matter before endurance exercise. Well-stocked glycogen stores before a longer session can genuinely improve its quality. That’s one reason why carb-loading strategies are used before marathons and other long races. In this context carbohydrates aren’t an extra – they’re part of the strategy.
Do you need extra carbohydrates during a workout?
That depends on how long the effort is and what kind it is.
For most standard recreational sessions (e.g. a 45-minute CrossFit class), your overall carbohydrate intake across the day matters more than taking them in during the session itself.
Studies on people doing high-intensity functional training suggest that in shorter sessions eating carbohydrates during exercise doesn’t always improve performance. That’s useful to know, because it shows there’s no need to overcomplicate simple things. For most active people, what they eat before and after training matters more.
Carbohydrates and your body shape – should you be afraid of them?
This is one of the most persistent myths.
Carbohydrates on their own don’t automatically make you gain fat. That comes down to your diet as a whole and your energy balance.
What’s more, cutting carbohydrates too drastically can worsen the quality of your training, increase fatigue and make recovery harder. For some people it can also affect mood and energy levels during the day.
For active people the question often shouldn’t be “should I eat carbohydrates?” but rather “am I eating enough of them, from good sources?”
References
- Burke LM, Hawley JA, Wong SHS, Jeukendrup AE. Carbohydrates for training and competition. Journal of Sports Sciences, 2011. DOI: 10.1080/02640414.2011.585473
- Cermak NM, van Loon LJC. The use of carbohydrates during exercise as an ergogenic aid. Sports Medicine, 2013. DOI: 10.1007/s40279-013-0079-0
- Ivy JL. Carbohydrate intake and recovery from exercise. Science & Sports, 2004. DOI: 10.1016/j.scispo.2004.05.005
- Impey SG et al. Fuel for the work required: carbohydrate periodization and glycogen threshold hypothesis. Sports Medicine, 2018. DOI: 10.1007/s40279-018-0867-7
- Rountree JA et al. Efficacy of carbohydrate ingestion on high-intensity functional training performance. Sports, 2017. DOI: 10.3390/sports5030061
- Thomas DT, Erdman KA, Burke LM. Nutrition and athletic performance. Journal of the Academy of Nutrition and Dietetics, 2016. DOI: 10.1016/j.jand.2015.12.006
