Triathlons, Statins and CPK Levels

Triathlon Training

I’m taking my triathlon training a little more seriously this year. I’ve been following a sensible training plan and have just about finished a winter ‘Base Phase’ of training. With my coach we’d been gradually increasing the volume of training over the past couple of months and I’m now just beginning to increase the intensity too and do some strength training.

I wasn’t feeling fast, but I was feeling fairly fit and fairly good.. I’m just finishing a recovery week and was raring to go with another couple of hard weeks training.


I went to the doctors yesterday though and while I was there asked him about the statins that I’m on (and have been for a few years), and how they might affect athletic performance. Things became a little complicated here and there is no right and wrong answer. The long and short of it is that there is quite a bit of evidence that statins do have a negative impact on athletic performance.

They do if course also lower my cholesterol levels and therefore have a long-term health benefit from that point of view. The question is do the benefits outweigh the possible side-effects.

Side Effects

Once of the most common side effects of statins is muscle soreness. This can be felt as a soreness, tiredness or weakness in your muscles. The pain can be a mild discomfort, or it can be severe enough to make your daily activities difficult. Very rarely, statins can cause life-threatening muscle damage called rhabdomyolysis. Rhabdomyolysis can cause severe muscle pain, liver damage, kidney failure and death.

Thankfully, as far as I know I don’t suffer from any of these side-effects. I do almost always have some muscle soreness, but that is I think always associated with the training that I do. This is normal and is known as delayed onset muscle soreness (DOMS) and is caused by the fact that the training actually destroys muscle fibres and therefore makes them sore. The training effect that you see comes about by a super-compensation mechanism when the body repairs these muscles and actually makes them stronger. If I stop training or even have a few easy days then my muscles feel fine. What I can’t be sure of though is whether or not the statins make the post-training muscle soreness worse than it would be if I weren’t on them.

Nor can I tell if the statins are having an adverse effect on my athletic performance. Side effects from statins are of course relatively rare and the effects vary in degree from individual to individual. Statins work by slowing your body’s production of cholesterol. Statins may affect not only your liver’s production of cholesterol, but also several enzymes in muscle cells that are responsible for muscle growth.

Although I might not have any physically discernable side effects, the statins could still be affecting my muscles and therefore affecting my training.

CPK Levels

Creatine phosphokinase (CPK) is an enzyme found mainly in the heart, brain, and skeletal muscle. It is an important enzyme in the production of energy in muscles. When muscles become damaged it leaks out into the blood where it can be detected in a blood test. Elevated levels of CPK in the blood are therefore an indication of damage to muscle.

If the use of statins is causing muscle damage then this will elevate CPK levels. Having a CPK test can therefore show whether or not statins are likely to be having an adverse effect on your muscles which could be leading to a detriment in athletic performance. It would seem as though I need a CPK test. As luck would have it I was due for a blood test anyway to check my cholesterol levels as I had recently changed from one statin to another, so the doctor added a CPK test to the list of tests.

The only rouble with this is that CPK levels are also elevated by exercise. The muscle breakdown caused by strenuous exercise naturally causes the release of CPK into the bloodstream, so having a CPK test whilst exercising won’t show us anything. I therefore have to stop training for a week before the tests so that we can see if the statins are causing any muscle damage.

A Break in Training

The last thing I wanted to do at the moment was to have a break in my training, things were going well and I was feeling keen. After a rest week – a rest week for me consists of two 30-40 mile bike rides, 3 swim sessions, 1 power circuits session and 2 steady runs – I was looking forward to some hard weeks, I didn’t want to take a break during those, so I decided to do the test as soon as possible. The fact that I’m coming off a rest week means that my muscles are well recovered and shouldn’t be damaged too much anyway, I only did a swim on Thursday, so I missed my bike ride yesterday (Friday) and will now do no exercise until after my blood test on Tuesday.

That won’t be quite a full week without exercise but my muscles should be in fairly good shape after a rest week. Add onto this another full 4 days of doing nothing, which is VERY rare for me and they should fully repaired meaning that the CPK test will hopefully be an accurate representation of the effect of the statins on my muscles. I’ll be straight back to the training on Tuesday evening after the blood tests though and although I’ll have missed a few sessions will just pick up where I left, put the missed sessions behind me and consider it an elongated rest period. It will put me back a bit, but not too much.

The Results

Of course, there is no point having such a test if you don’t know what you’ll do once the results come back.

If the CPK levels are normal, then all is well. The statins probably aren’t causing any adverse effects on my muscles so I can continue taking them, continue to keep my cholesterol levels in check and continue training without any excuses!

If the CKP levels are elevated then I have some choices to make. I’ll probably stop taking the statins, not only because they are affecting my athletic performance but because any detrimental effect to my muscles can’t be a good thing in the long term. I’ll then have to keep a very close eye on my cholesterol levels. If these start creeping back up again – which they are likely to do – then it might be time to look at alternative methods of cholesterol level control. This might be in the form of a different type of statin, or a different type of drug.

The Alternatives

I’ll need to talk to my doctor about these, but there is some evidence that the statin I’m currently on (simvastatin) may be more likely to cause muscle pain as a side effect than other statins. Maybe a different one will be better. Finding out though will mean a period of trying different ones and testing cholesterol levels and CPK levels to ascertain which ones work best with out the muscle damage side-effects.

Other cholesterol-lowering medications such as Ezetimibe (Zetia), a cholesterol absorption inhibitor medication are also available. This may be less likely to cause muscle pain than statins, or may reduce muscle pain when taken with a statin. However, the effectiveness of ezetimibe compared with statins in terms of its ability to lower your cholesterol may not be as good.

Another possible option is Coenzyme Q10 supplements. These may help to prevent statin side effects in some people.

Hopefully the test will come back with normal levels of CPK and I won’t need any of these, but if not I’ll be back to the GP to see what I should do. It’s annoying that I have to take a week off training, but finding out now if the statins are likely to be preventing me from reaching my full potential athletically will be a good thing in the long run.


4 Responses

  1. Alan says:

    I’ve had the results of my blood test back and it’s all good news.

    My CPK levels were 84 U/L, well within the expected ‘normal’ range of 20-200, so it doesn’t seem as though the statins are having to much of an effect on my muscles. My Cholesterol levels were good too. 4.4mmol/l total cholesterol and 2.2mmol/l LDL so it would seem as though the statins are working on that front.

    All good news as it means I can keep taking the statins and therefore keep my cholesterol levels low, but all safe in the knowledge that they aren’t affecting my ‘athletic performance’ – No excuses now.


    • Derek says:

      Alan – I was researching CPK for a patient and stumbled onto your website via ‘Triathlons, Statins and CPK Levels’. Unrelated to my patient, but she does happen to be a triathlete. Anyway, from what I know, it would be very important for you to take CoQ10 if you are on a statin. Some good information on on this (you might have to convert the units). Sounds to me like your Chol. levels are pretty good (without knowing all the details). Perhaps you should do some more research into this and talk to your MD. If big pharma had their way, everyone would be on a statin. Hope you don’t mind the unsolicited advice. Cheers and happy training.

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Alan Cole

Alan is a Freelance Website Designer, Sports & Exercise Science Lab Technician and full time Dad & husband with far too many hobbies: Triathlete, Swimming, Cycling, Running, MTBing, Surfing, Windsurfing, SUPing, Gardening, Photography.... The list goes on.

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