|Sometimes lab values are deceiving - specifically if allegedly pathological elevations of kidney, liver and (heart) muscle enzmes are a perfectly physiological reaction to exercise.|
In fact, the CK-levels can be elevated more than 100-fold after an intense workout (Pettersson. 2008). Accordingly, Mougios, et al. (2007) attempted to develop revised reference values for athletes in their 2007 study. The scientists' test revealed that CK levels of >1000 IU/L in male and 513 IU/L in female athletes would be better cut off levels for athletes who are still training than the regular upper limit of <208 IU/L.
Closely related to the CK-levels, which are unquestionably the #1 reason your doctor may want to call an ambulance, despite the fact that all you're suffering from is heavy deep onset muscle soreness, are elevated transaminase levels (see time course of elevation in the Petterson study).
|Figure 1: Changes in serum enzyme levels after exercise in trained and untrained subjects in response to 15 minutes treadmill running and an 8k run (Fowler. 1962).|
As the data from a 1962 study by Fowler, et al. indicates, even 15 minutes on a treadmill can lead to significantly elevated ALT (back in the day the enzyme was still called "GPT") and AST ("GOT") levels. An 8k run can increase ALT and AST by more than 150% (see Figure 1). In that the extent of ALT & AST elevations probably depends on the individuals' susceptibility to exercise induced protein breakdown, which is the actual reason the enzymes which breakdown the protein debris in the liver are elevated.
As it is the case with the creatine kinase enyzmes, many primary physicians and scientists are unaware of the connection and the long-lasting elevations of serum transaminases in response to hard workouts.
|Figure 2: In trained marines AST (=SGOT), ALT (=SGPT) react significantly less pronounced (Schlang. 1961)|
Chronically elevated liver enzymes should still not be taken lightly. Even if they don't indicate liver damage, they could be a sign of chronic overtraining. After all, Hunter et al. (1971) were able to show that training reduces the initially exuberant increases of the aminotransferases significantly.
Speaking of not taking lightly, one thing you shouldn't take lightly either is your doctor's suspicion that you may have developed a heart disease.
More specifically, Elliott and La Gerche have recently been reporting that strenuous endurance exercise (SEE) is associated with acute depression of RV systolic function, thus suggesting that exposure to repeated bouts of SEE can have potential long-term consequences. La Gerche and Claessen argued that left atrial pressure is increased during SEE, thereby increasing pulmonary artery pressure. As Fabian Sanchis-Gomar et al. point out in an editorial comment, they thus stated
"that frequent episodes of increased RV work induced by long-term SEE can promote compensatory RV remodeling, increase myocardial damage biomarkers such as troponins and B-type natriuretic peptide, or even accelerate heart failure (HF)" (Sanchis-Gomar. 2015).The Spanish researchers do yet highlight that to the best of their knowledge the bulk of the evidence available supports that the above mentioned alterations which include among other the cardiac-specific creatine kinase marker are rather transient, with a dose-effect relationship existing for exercise intensity and duration.
"Physicians and health professionals should be aware that healthy individuals who engage in SEE sport events could exhibit acute, transient cardiological features that are apparently compatible with cardiac diseases, yet these alterations are attributable in most cases to transient physiological responses rather than pathological status"(Sanchis-Gomar. 2015).Against that background, it may be a good idea to take two weeks off in order to retest, if your doctor says that your biomarkers suggest that you may be suffering from heart disease.
- Elliott, Adrian D., and Andre La Gerche. "The right ventricle following prolonged endurance exercise: are we overlooking the more important side of the heart? A meta-analysis." British journal of sports medicine (2014): bjsports-2014.
- Fowler, William M., et al. "Changes in serum enzyme levels after exercise in trained and untrained subjects." Journal of applied physiology 17.6 (1962): 943-946.
- Hunter, J. BARRY, and JERRY B. Critz. "Effect of training on plasma enzyme levels in man." Journal of applied physiology 31.1 (1971): 20-23.
- Mougios V. Reference intervals for serum creatine kinase in athletes. Br J Sports Med. 2007 Oct;41(10):674-8. Epub 2007 May 25.
- Pertusi, Raymond., R. D. Dickerman, and W. J. McConathy. "Evaluation of aminotransferase elevations in a bodybuilder using anabolic steroids: hepatitis or rhabdomyolysis?." JOURNAL-AMERICAN OSTEOPATHIC ASSOCIATION 101.7 (2001): 391-394.
- Pettersson, Jonas, et al. "Muscular exercise can cause highly pathological liver function tests in healthy men." British journal of clinical pharmacology 65.2 (2008): 253-259.
- Sanchis-Gomar, Fabian, et al. "Long-term strenuous endurance exercise and the right ventricle: Is it a real matter of concern?." Canadian Journal of Cardiology (2015).
- Schlang, Captain HA, and C. A. Kirkpatrick. "The effect of physical exercise on serum transaminase." The American journal of the medical sciences 242.3 (1961): 338-341.