Isotonic sports drinks are among the first supplements every dedicated cyclist should consider, but they vary significantly in quality and effectiveness.
Fortunately, we sat down with Dr Tim Podlogar to shed some light on what’s really going on.
Tim, we know you’re very busy with your scientific work and your role as a nutritionist in a professional cycling team, not to mention your own cycling endeavours. Thank you for taking the time to talk to us.
No problem. I’m always happy to share some of my knowledge with your athletes.
Today we’d like to discuss isotonic sports drinks. Why are they so important?
Carbohydrates are a source of energy, the other two being protein and fat. Of course, during exercise, carbohydrates are the most important.
But carbohydrate stores in the body are limited. Once they run out, we hit the wall, i.e. run out of energy.
To sustain high-intensity exercise, we must ingest carbohydrates. Many athletes make the mistake of only starting to consume them once they begin to feel fatigue — by then it’s too late.
You must ingest carbohydrates from the very beginning, as this is the only way to slow down glycogen depletion.
Many athletes still don’t understand the role of carbohydrates during exercise. How does poor carbohydrate availability really affect performance?
Many athletes mistakenly believe they can perform at their best until they completely run out of energy, but that’s not how it works.
If carbohydrates are not available, the consequences are felt immediately.
One of them is increased muscle catabolism, i.e. the breakdown of muscle tissue. I’m sure nobody wants that.
Muscle cramps are also a common consequence of poor carbohydrate availability.
Another area that suffers is muscle recovery. If you want to train the next day, you’re doing yourself a huge disservice if you neglect your carbohydrate intake.
OK, we get it, carbohydrates are a must during exercise. But what quantities are we talking about?
It all depends on the number of watts a cyclist is able to produce during physical activity. Basically, it comes down to exercise intensity and fitness level.
For most recreational cyclists, anywhere from 40 to 60 grams per hour should suffice.
But advanced cyclists, and definitely professionals, should consume up to 90 grams per hour.
Unfortunately, such a high intake often leads to one of the most common problems with isotonic sports drinks — digestive issues.
The bane of all endurance athletes. Are there any other issues with isotonic sports drinks?
Having worked with countless endurance athletes, isotonic sports drinks mainly have three problems — low energy efficiency, muscle cramps, and digestive issues.
Ironically, digestive issues are the consequence of athletes trying to prevent the first two problems. To have energy and prevent muscle cramps, you need to ingest more carbs, but ingesting large amounts of the wrong types of carbs leads to digestive issues. It’s a vicious circle.
A vicious circle indeed. But has there been any progress in terms of resolving these issues?
Isotonic sports drinks are nothing new, really. But in terms of improvement over time, I see a lot of misguided approaches from manufacturers — they might improve the packaging or add “magic” ingredients, such as coconut water or cinnamon (I’m not kidding).
The flavours change, the names change, fruit gets five different adjectives, and many add magnesium as the ultimate tool to prevent muscle cramps.
To boost sales, marketing teams use well-known athletes to promote their products.
And yet, manufacturers continue to fail to solve the core problems of isotonic sports drinks, leaving many athletes dissatisfied with their fuelling products.
Were you one of these athletes?
Yes.
It led me to the point where I realised I needed to take matters into my own hands.
That’s how I partnered with Nduranz — a brand that shared my vision to create the best possible supplements for endurance athletes.
The result of our collaboration is the Nrgy product line, including Nrgy Drink 45, Nrgy Drink 90, and Nrgy Gel 45.
Nrgy Gel 45 Box
Nrgy Drink 45
Nrgy Drink 90
Nrgy Gel 45 with Caffeine Box
How did Nduranz solve these issues?
The main factor is the carbohydrate ratio.
Years ago, Prof. Asker Jeukendrup at the University of Birmingham was the first to discover that consuming only glucose caps absorption at 60 grams per hour. Once fructose was added, absorption rates increased, leading to a significant improvement in fuelling efficiency.
They determined the best glucose-to-fructose ratio was 2:1, although this ratio was established somewhat arbitrarily and had little scientific backing.
Many brands still use this ratio as the optimal carbohydrate balance.
But it’s not the ratio Nduranz chose for their products — why not?
From the beginning, I advocated for a 1:0.8 glucose-to-fructose ratio.
Later, studies by Prof. David Rowlands from New Zealand confirmed that my assumption was correct. I was pleased to see that Nduranz trusted this approach and used the ratio across all their fuelling products.
Considering feedback from both amateur and professional athletes, they made the right choice, as this ratio proved highly efficient both for energy availability and for reducing digestive issues.
Tim is an avid cyclist, so he knows first-hand what athletes need during intense training sessions.
What makes the combination of glucose and fructose so effective?
Most carbohydrates you can buy in a shop contain only glucose — bread, pasta, rice, maltodextrin, it’s all glucose. Fructose is rarer, found in varying amounts in fruit and honey.
The key factor is that glucose and fructose use two different carbohydrate transporters in the body. This increases absorption rates from 60 grams per hour for glucose alone to 90 grams per hour.
Another factor is that fructose must first be transported to the liver before being converted into glucose or lactate. For this reason, it was previously avoided as an energy source, but it turns out this process actually improves energy efficiency.
But isn’t fructose considered harmful to health and linked to fatty liver disease?
That’s a long story.
Yes, it can be — but only if consumed in large amounts while physically inactive. In contrast, for an endurance athlete during high-intensity exercise, fructose is not only safe but beneficial.
Very interesting. But isotonic sports drinks are not just about carbohydrates, are they?
No, they are not. Another important factor is hydration.
There seem to be many misconceptions regarding proper hydration. Could you explain how it really works?
Sure.
Hydration is all about maintaining electrolyte balance in the body.
For an athlete, there are three focal areas: the drink or supplement they use, blood, and sweat. Most research focuses on blood, but for athletes the most important is sweat — we need to replace the electrolytes lost through sweat.
By sweating during physical activity, we lose primarily water and salt.
If we only drink water, sodium concentration drops, leading to problems. On the other hand, if we consume too much sodium, this can cause stomach issues and increased thirst.
Isotonic drinks are not only for fuelling, but also for hydration.
OK, hydration is important, we get it. Any other issues we should know about?
As a matter of fact, yes.
Electrolytes affect cell volume. If sodium concentration increases, water leaves cells (including muscle cells) and enters the bloodstream. This happens during dehydration and is not good news for bodily functions.
On the other hand, if blood sodium levels drop, water enters cells and they begin to swell. This wouldn’t be a problem if not for the brain. Inside the skull, brain cells have very limited space, so swelling can cause serious damage. This is called hyponatraemia, and in severe cases it can be fatal.
That’s grim. But it probably doesn’t happen very often, right?
Unfortunately, it’s more common than you might think.
You seem to know your way around this topic. What about magnesium? You mentioned earlier it is a common inclusion in many isotonic sports drinks.
The thing is that many athletes still believe magnesium prevents muscle cramps, and manufacturers are happy to support that claim.
If you ask me, that’s nonsense. In fact, when we are dehydrated, electrolyte concentration in the blood increases. This means their availability is higher, not lower.
There is also no research confirming any link between muscle cramps and electrolyte intake.
The only scenario where electrolytes could play a role in cramping is if someone only drinks water, which dilutes electrolyte concentration in the blood.
Not to mention that magnesium is very often another cause of digestive issues, especially in large amounts.
That’s very interesting. If magnesium is not the answer, how can we avoid muscle cramps?
Let me first explain what a muscle cramp is.
It is an involuntary muscle contraction that prevents the muscle from relaxing. The only way to stop it is to stretch it, which deactivates the nerve signal in the affected muscle.
It is essentially a signalling error in the nervous system, not an electrolyte imbalance — you can’t fix electrolytes by stretching, can you?
Generally speaking, cramps occur during intense effort, in hot environments, or at the end of exercise. All of this is linked to low energy availability, namely carbohydrates, and partly muscle micro-damage.
In simple terms, cramps occur when exercise intensity exceeds the body’s capacity.
So, if we understand correctly, the best way to prevent cramps is by consuming sufficient carbohydrates?
That’s correct.
Tim, thank you for your time.
You’re welcome.
