The goal of strength training is to strengthen the muscles. The process actually involves damaging the muscles so that they repair, which grows the muscle. The injury isn’t major. It’s many micro-tears that get woven back together, generating more muscle than before.
And this is why many gym-goers think they have liver disease if they get their AST levels checked. If that seems like an illogical leap, allow us to explain.
Where AST Comes From and What It's Used to Measure
AST (aspartate transaminase) is an enzyme that's generated in the muscles, heart and the liver. This is why there can be confusion when AST levels are elevated because AST is measured to gauge liver function, not muscle function.
The primary role of AST is to metabolize amino acids. It converts amino acids that are in protein into energy the body can use.
But AST isn't freefloating in the blood. It's held in tissue cells. Under normal circumstances there's actually very little AST in blood. AST shows up in the blood when a person has had a heart attack or tissue within muscles or the liver is damaged or inflamed. When the tissue is compromised, the cells that hold the AST enzyme begin to leak.
AST can show up in the bloodstream by leaking out of the microtears of muscles after a strength training session. Or it can show up because a person has liver disease that is damaging tissue inside the organ. Or it can be the result of both muscle microtears and liver damage.
The False Positive That Can Throw Things Off and Why It Happens
You go to the gym regularly, you eat healthy and you have an annual physical each year. The next step is at-home blood testing for specific biomarkers. Or maybe you've already tested before and now you want to look at more metrics because a high AST level has you concerned.
Blood testing provides valuable information, but it has to be interpreted correctly and taken in context. This is especially true when you're measuring AST between workouts.
There are some things to know going into an AST test:
Regular strength training (2+ times a week) can keep AST at continuously high levels since it can take up to seven days for the enzyme to regulate after a workout.
Some of the supplements that some gym-goers take could actually be causing liver damage, leading to high AST from the liver and muscles.
High protein diets and/or protein supplements can further elevate AST because excess amino acids are being processed. This is a temporary condition that levels out when protein intake goes down.
Working out regularly is highly beneficial for your health, but it's important to remember that it's a lifestyle choice that can be reflected in your biomarkers. Going into blood tests with that understanding is important since exercise can have unexpected consequences that may make it appear there's a health issue when it's nothing more than a false positive.
How Gym-Goers Can Know If AST Levels Are From the Liver or Muscles
Before you disregard that blood test that indicated you have elevated AST, understand that the gym time may not be the cause. If you're at the gym regularly lifting weights further evaluation is needed to determine if the AST levels are influenced more by the liver or muscles.
One way to figure out where the AST is coming from is by looking at the enzyme levels alongside other biomarkers. Typically, if your GGT and ALT liver enzymes are normal, the AST is most likely from the muscles. GGT is very closely related to liver function. When this number is normal liver injury typically isn't a concern.
Another biomarker you can look at is creatine kinase (CK). High levels of CK occur after muscle damage. High CK + high AST suggests muscle damage is the cause of both.
Choose Health specializes in at-home blood testing for a wide variety of biomarkers. We make it possible to measure markers in a comprehensive, accurate way by testing multiple markers at once so you have a complete picture.
Gym-Goers Can Test Their Biomarkers Quick and Easy From Home
Knowing how your body is functioning from the inside is convenient with Choose Health. Our affordable blood testing kits are mailed to you, the directions are easy to follow and the results are from CLIA/CAP accredited labs to ensure accuracy.
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