Creatine kinase (CK) is an enzyme present in many tissues including the heart, brain and skeletal muscle. Creatine kinase is a biomarker for muscle damage. High levels of creatine kinase in the blood indicate recent muscle injury.
There are three major forms of creatine kinase found in the body, also known as isoenzymes: CK-MB found in the heart muscle, CK-BB found in brain tissue and CK-MM found in skeletal muscle.
A creatine kinase blood test will help to identify if you have had any recent muscle damage. The result is particularly useful if you participate in regular exercise and will allow you to monitor damage to your muscles. High-intensity exercise and exercise which repetitively uses the same muscle groups may result in muscular injury.
Usually, elevated levels of CK are consistent with muscular pain and/or weakness. However, the levels may also be raised after a heart attack where the heart muscle has been damaged. Monitoring CK levels can be used to aid recovery because serial results where levels peak and fall indicate the damage to the muscle has lessened, whereas increasing levels indicate the damage is increasing.
A creatine kinase test is included within our Ultimate blood test, which includes analysis of 50 biomarkers integral to health and wellbeing.
CK is important in cellular energy metabolism. The purpose of an enzyme is to speed up (catalyse) a chemical reaction. CK catalyses the transfer of high-energy phosphate from ATP (adenosine triphosphate), the main energy carrier in all living organisms, to creatine. The reaction enables the storage of energy as phosphocreatine.
Another function of CK is it helps to maintain ATP homeostasis in muscle cells, helping to produce ATP for muscle activity. Its role in cellular energy metabolism is essential for the production and maintenance of energy within the muscles, enabling them to meet the demands placed upon them.
Because elevated CK levels are a sign of damaged muscles, you may experience some pain after the injury has occurred. The pain may be so severe that it affects your ability to complete your daily tasks, particularly if it prevents you from using the muscle at all.
It is advised that you rest the affected muscle group after an injury has occurred to aid in the healing process. If you continue to use the muscle while it is injured, you could potentially cause more damage and increase recovery time. Equally, if you are training, e.g. for a marathon, an injury can affect your training significantly which may also impact on your confidence and self-esteem.
If you are worried about your CK level or just want to check where you fall on the range, you can test your level with a simple at-home blood test.
There is usually a small amount of CK present in the blood which is present from skeletal muscles.
An increased CK level can indicate skeletal muscle damage:
CK levels can be increased after a heart attack. Until the mid-90s blood CK levels were a key tool in the diagnosis of a heart attack. However, this has since been replaced with the muscle protein, troponin.
The most common causes of muscular damage are:
The pain experienced following muscle damage can vary from hardly feeling anything at all to severe pain which immobilises the muscle completely.
It is important to lead a healthy lifestyle to avoid muscular injury. Muscle recovery can be aided by eating a nutritionally balanced diet and ensuring you get good recovery periods between exercise. It is important you incorporate all the essential nutrients into your diet to avoid deficiencies.
Some research has shown that consumption of a New Zealand blueberry beverage helps to speed up the recovery of muscles. Blueberries are a good source of natural antioxidants which are highly effective at managing reactive oxygen species-mediated tissue damage. Many antioxidants contain anti-inflammatory properties which may help to aid recovery following muscle damage. A well-balanced diet, largely made up of natural whole foods which have been subjected to minimal processing. Foods such as fruit, vegetables and whole grains are best and will contain many of the vitamins and minerals the body needs to function and will also aid in the healing process. 
Exercise can increase creatine kinase levels because the muscles will be working hard and will experience some damage during training. Low-intensity exercise is less damaging than high-intensity exercise, so it may be good to alternate between the two particularly after an injury.  If you are injured it is paramount that you rest sufficiently between exercise sessions and rest the muscle affected. A week-long break after sustaining an injury should be enough time for creatine kinase levels to drop to within a normal range.  However, you should follow any medical or professional advice you have been given.
 Lab Tests Online. (2019). Creatine Kinase (CK) Test. Available at: https://labtestsonline.org.uk/tests/creatine-kinase-ck-test
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