Leg cramps can affect all cyclists, regardless of experience but lactic acid is there for a reason – it’s a signal for you to stop what you’re doing

You’ve finally achieved it, ridden that extra mile! You feel great about it too – at last accomplishing one of your goals is fantastic, but in the process you’ve pushed your body to the limits and your feeling leg cramps. Does this sound familiar? Interestingly, this scenario is common to both elite cyclists and beginners alike.

In this article I’m going to explore exactly what is going on in your body during and after extreme exercise, the role lactic acid plays and perhaps most importantly, what you can do about it to prevent leg cramps.

Most commonly, lactic acid build-up is felt as a burning or aching sensation in the muscles. It happens to all athletes but for us cyclists, we are going to feel it most in the calf muscles. But lactic acid is there for a reason – it’s a signal for you to stop what you’re doing.

If you don’t heed this warning, excessive build up can cause symptoms from nausea, exhaustion and the aforementioned leg cramps, plus an overriding sensation of fatigue. Worst yet, it’s the morning after when you’ll really start to regret it as your muscles go into hangover mode.

How Leg Cramps Occur

Let’s start at the beginning – respiration. When your body respires, it converts the air you breathe into usable energy for not only your muscles but every cell in your body. When you step onto your bike and start pedaling, you’ll immediately begin to breathe faster because your body needs more oxygen to produce more energy at a quicker rate. This is known as aerobic respiration.

Chris Froome VO2 Max TestHowever, the more you pedal, the harder it becomes for your heart to pump the oxygen around your body – after a certain point it simply cannot supply oxygen fast enough, which is when the body enters into anaerobic respiration.

Glucose is the vital ingredient in producing this energy. It comes from two places. Firstly, the food we eat is broken down by the gut into its constituent nutrients and carbohydrates. Secondly, glucose is produced by the liver in a process called gluconeogenesis – this is where the glucose your gut extracts from the food is broken down into a simpler sugar, stored in the liver, and then converted back to glucose when needed (interpret that as those days you skip breakfast!).

In both cases, bigger molecules are broken down into simpler ones. During the process, glucose reserves are broken down in to smaller molecules of which one is pyruvate. During aerobic respiration, when body has enough oxygen, pyruvate is released into blood supply to be metabolised by the body into more energy. During anaerobic respiration, the body cannot directly metabolise the pyruvate because there isn’t enough oxygen to do so.

How does the body get deal with pyruvate? By breaking it into a smaller molecule called lactate, aka lactic acid.

Lactate is the body’s answer to not enough oxygen because it allows glucose to be further broken down – producing more energy, enabling you to ride that extra kilometre. As Scientific American points out, research shows that the body can undergo the anaerobic pathway of metabolism for up to three minutes – the flipside to this is that lactate concentrations in your muscles will increase significantly.

Why Does Lactic Acid Matter?

Lactate Recycle Model

Well, the issue here is that your calf muscles are not the only tissues that need energy. Actually, every cell in your body needs energy. The build-up of lactate increases acidity in your muscles, causing an imbalance in other metabolites (the other by-products of the rest of your cells metabolising). The trouble is that the higher the acidity, the worse the body becomes in breaking down glucose.

It might not seem it at first glance, but this is actually very useful. It’s a really smart way of your body forcing itself to stop working so hard. What does this mean for the cyclist? Put simply: a recovery period – go ahead, take a well earned break!

Cyclist with leg cramps

Muscle Hangover Syndrome

Lactate is cleansed by the body in around 1 hour but we have all felt the effects of over-exertion the day after, or the muscle hangover syndrome. This is known as delayed-onset-muscle soreness, aka DOMS, and it usually lasts for a few days. Current research has shown that this soreness is due to damage of contractile muscle fibres. Whenever there is damage to the body’s cells, the first response is always inflammation.

Inflammation is a natural and intelligent response to damage. It’s the body’s most efficient response to help heal the damaged muscle fibres. It involves the dilation of local blood vessels, which makes them leaky. This happens because the body is trying to get as many nutrients to damaged cells in order to help repair them. Herein lies the causes of stiffness in the days to come.

How Cyclists Can Recover from Lactic Acid Build-Up and Muscle Fatigue

First and foremost, take regular breaks if you need it. As mentioned before, the sensory perception of lactic acid is the body’s way of telling you to have rest. After all, the body will stop itself if necessary. But remember, you don’t want to get to this stage due to DOMs.

The inflammatory response to the damaged muscle fibres is of particular interest to the scientific community. Recent research has been conducted into a group of medicaments known as non-steroidal-anti-inflammatory-drugs, or NSAIDs, in order to stop the inflammatory response within the damaged muscle fibres.

However, proceed with caution here! Keep in mind that the inflammatory response is the body’s first and foremost mechanism of repair and defence. By inhibiting it you are stopping the healing process. So if you take NSAIDs be aware that it make take longer for your muscles to actually heal.

Cyclist Stretching

Stretching before and after long bouts of exercise is always a good idea. Muscles are essentially lots of thick and thin strands of protein, that slide against each other to work. Stretching helps loosen these strands, and begins the pumping of blood to the region which is important for oxygen and nutrient supply. After your ride, a stretch can help ‘unwind’ or untangle clumps of strands.

There are a range of topical creams and balms on the market for muscle soreness, but perhaps it is more the massaging technique that really makes a difference to the repair of muscles and dispersion of lactic acid as opposed to the actual ointment itself. In a similar nature, having a rest in a sauna or steam room can also be beneficial.


In summary, lactic acid is a useful substance that is a by-product of energy production during prolonged bursts of exercise. As a general rule of thumb, if your body is saying it needs a break, then take a coffee stop. And remember, warming up and warming down can save you from the soreness that comes when reaching your riding goals.

Here’s a quick summary of what causes leg cramps in cyclists ..

  1. Aerobic Respiration – when we cycle, we respire, generating more oxygen
  2. Anaerobic Respiration – body cannot directly metabolise pyruvate due to insufficient oxygen
  3. Lactate concentrations build-up in muscles
  4. Lactate / lactic acid increases acidity in the muscles
  5. Higher acidity levels reduce the body’s ability to break down glucose
  6. Leads to DOMS (delayed onset muscle soreness), which causes inflammation in muscles

.. and how cyclists can prevent lactic acid build-up;

  1. Cyclists should at this point rest, for around an hour, to recover
  2. Stay hydrated
  3. Cycle regularly to maintain fitness levels
  4. Stretch before and after cycling