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Top Supplements to Improve Exercise Performance

by Matt Durkin
MSc Nutrition Specialist

Supplements and exercise go together like eggs and bacon. Whether you’re trying to build muscle in the gym or you spend your weekends running marathons, you’ve no doubt been tempted by all the many options on offer. But do any of these supplements really live up to their billing?

In this article, we’re going to take a look at the science behind supplementation for sports or exercise performance. For the purposes of this article, we can define this as supplements that help you to exercise at a greater intensity or for longer periods of time. That is to say, they can have a direct effect on your activity levels – and your performance as a result. 

If you want to take your performance to the next level then here’s what you should be considering…


That cup of coffee you rely on to kick-start your day could be doing a lot more than you might realise. So much so, in fact, that it currently appears on the list of substances banned by the International Olympic Committee. That being said, you would need an extremely high dose to exceed the threshold set by the IOC. So what are these potent effects on sports performance?

Numerous studies have demonstrated two particular effects over and over. Firstly, caffeine can increase reaction times - both mentally and physically. This can be particularly beneficial for sports that require sudden bursts of activity, such as football or cricket.

The second effect experienced after consumption of caffeine is that it improves skeletal muscle contraction. It’s little surprise that anything that positively influences muscle contractions can assist in exercise performance. 

Caffeine is such a well-known sports supplement that the direct effects have been tested across a huge range of different disciplines. Interestingly, the results are far from uniform. For example, little impact is seen in resistance training, but performance is significantly improved in endurance activities or those requiring regular stops-and-starts. 

This makes caffeine ideal for many team sports such as football, rugby or cricket, which are typically characterised by oscillating periods of exercise intensity. It can also be helpful for long-distance runners, cyclists and triathletes, to name just a few endurance activities.  

Research has shown that the body can very easily become attuned to regular caffeine intakes. Under such circumstances, the beneficial effects may start to decline over time with repeated use. Preventing this drop-off is important if you are to experience performance boosts when required.

The “optimal” amount of caffeine can vary from person to person, however, broadly speaking a good rule-of-thumb is that roughly 3-6mg/kg of body weight is effective. Taking higher doses doesn’t necessarily lead to further improvements, so try not to overdo your caffeine intake. 

Lastly, it’s worth highlighting that research by the International Society of Sports Nutrition has shown that the performance-enhancing effects of caffeine are greatest when it is consumed in supplement form, as opposed to merely from drinking a strong coffee. So for best results invest in caffeine capsules, or find another supplement that includes caffeine powder. 


Glucose is a key energy source used by your muscles during exercise. Fatigue can set in as levels of freely-available glucose start to fall, leading to drops in overall performance.

Glucose is typically stored as glycogen within both the muscles and the liver for easy access. Unfortunately, there is only so much that can be stored in this way, and around 90 minutes of exercise is all that is required to become depleted. The more intense the exercise, the sooner this typically occurs. Worse, it takes time for the body to replenish these levels as a result of digesting food, and that lag phase can make all the difference between 1st and 2nd place. 

Fortunately, keeping your glucose levels up needn’t be challenging. The consumption of glucose-rich drinks is a tried and tested solution. These are most commonly used during exercise, but consumption beforehand can also help to increase availability. Additionally, continuing to drink after the completion of exercise can help to speed up replenishment of glycogen by muscles and the liver. 

The reason that these beverages work so well is that the glucose is available in such a “refined” format. This means that your body needs to do very little work to digest it into a usable format. 

Studies have shown that muscle glycogen levels drop much more slowly when a high glucose drink is consumed during exercise, leading to improved performance.

Optimal glucose intake levels depend on exercise intensity and length. Broadly speaking, a typical suggestion is 60 grams of glucose per hour of exercise in most cases, though for endurance events a higher level of 90 grams per hour is often touted. 


Creatine was first discovered in meat in 1835. It is naturally created within the body by combining specific amino acids and is found in the greatest density within the muscles. It has been described by the International Society of Sports Nutrition as “the most effective nutritional supplement currently available to athletes in terms of increasing high-intensity exercise capacity and lean body mass during training”.

The impact can be enormous. Some research has shown improvements in strength when resistance training of up to 15%, while others have demonstrated improvements in sprint speed by as much as 5%. 

If you want to work harder and boost your performance then creatine might just be the closest thing we have right now to a “silver bullet”. 

Perhaps most interestingly of all, it seems to partner perfectly with carbohydrates. Combining creatine with glucose seems to help the muscles to absorb and retain additional creatine better. 

So how do you take it? Most typically, creatine users use a “loading phase” to increase intramuscular levels, followed by a “maintenance phase” where their intake drops down to more modest levels.

Combining your maintenance intake with a source of carbohydrate – such as your glucose-rich beverage – is likely to be the best option for reliable performance improvements.  


When you exercise, your perspiration rate goes up. Even small amounts of moisture loss can negatively impact exercise performance. It’s crucial to replace the water lost through sweat and respiration if you are to maintain performance levels. However, the issue isn’t just remembering to drink enough fluids; you also need to think about electrolytes. 

Your body maintains a careful balance of water and electrolytes such as sodium. When you sweat during exercise it’s just as easy to lose electrolytes, which is why sweat can taste salty. After all, the chemical name of table salt is “sodium chloride”.

A loss in electrolytes can have a range of impacts on your exercise performance. The most common symptom is that of muscle cramps. As any long-distance runner will tell you a salty drink (or even a salt tablet) is the quickest and most effective solution. Of course, by then, the race might be lost. Best to maintain sodium levels before side effects arise.

A second issue is that optimal electrolyte balance is important for absorbing the water you drink. The so-called “osmotic balance” can mean that your body struggles to retain the water that you do drink. This means rehydration far less effective. Once again, therefore, a sports drink with added electrolytes can boost performance by maintaining hydration as well as preventing cramps.  

Whey Protein

Many of us know that consuming enough protein is crucial for building muscle when undergoing resistance training. What is rather less well known, however, is that it may also help to improve your performance while actually carrying out exercise. 

We’ve already talked about the importance of carbohydrate intake during exercise, with a focus on easily-digested and absorbed glucose. Some studies have expanded this concept, adding supplementary ingredients to sports drinks in order to assess the impact. As one study put it “carbohydrate-protein ingestion improves endurance performance to a greater extent than carbohydrate alone”. 

Muscle tissues typically become damaged during exercise, though the degree will depend on a range of factors including the length, intensity and type of exercise. Interestingly, it seems that consuming whey protein while exercising can help to “reduce protein degradation”. This, in turn, can help you to exercise longer and to recover quicker. 

Further research has sought to understand why this effect is experienced. It seems that protein helps to encourage glycogen synthesis in the muscles. As glycogen is the key energy source for exercise this makes perfect sense.

Lastly there is evidence to suggest that the consumption of protein alongside carbohydrates while exercising may also help to reduce post-exercise muscle soreness. 

Vitamin D

Your skin makes vitamin D in response to direct sunlight. As you’re no doubt aware, vitamin D is most famous for helping your body to absorb calcium, leading to strong teeth and bones.

Over the years, however, scientists have learned ever more about the impact of vitamin D on the body. The effects are far more wide-ranging than once believed, and there is some evidence to suggest that it may also help to support optimal exercise performance. 

Vitamin D seems to be linked to muscle contraction; no doubt because the major mechanism by which muscles move is down to changes in calcium. Studies have shown that athletes suffering from insufficient vitamin D experience weaker muscle strength, which subsequently improves with supplementation. 

One study of the effect claimed that increased levels of vitamin D can improve “strength, jump height, jump velocity, jump power, exercise capacity, and physical performance”. That’s quite a claim for something that so many of us take for granted. What’s more, this is far from the only study finding similar results. Yet another claimed that “Vitamin D was significantly associated with arm and leg muscle strength”.

Lastly there are suggestions that vitamin D may positively affect protein synthesis and oxygen use in the body, helping to improve post-exercise recovery times and to support exercise adaptation. 

That said, it is important to point out that these performance-enhancing abilities are most noticeable in those individuals who were deficient in the vitamin to begin with. If you already take a vitamin D supplement anyway then doubling your intake is unlikely to have quite the same result. 


There is a whole world of supplements that promise to improve your exercise performance. While many of the claims made by supplement companies are “questionable” at best, the science does seem convincing on a select few. 

If you’re serious about taking your chosen sport to the next level then caffeine, creatine and a good quality sports drink providing sugar, electrolytes and ideally a little protein too are likely to be your best course of action.

Oh, and either get out in the sun a little more or consider a vitamin D supplement – especially in the darker months of the year. 


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