If you lift heavily and get a blood test, there is a good chance your ALT and AST come back above the reference range. Most people read that as liver damage. Often it is not – it is the training.
This matters more for anyone using oral anabolic steroids than for anyone else, because it is the one group that most needs to be able to read a liver panel accurately, and the group most likely to misread it in both directions.
Why training raises ALT and AST
ALT and AST are not liver-exclusive enzymes. Both are present in skeletal muscle, and when muscle fibres are damaged – which is what a hard resistance session does on purpose – they leak into the blood.
The effect is not subtle. In one frequently cited study, fifteen healthy men with no weight-training history completed a single one-hour resistance session. Every one of them showed a significant rise in AST and ALT afterwards. AST rose faster and higher, and the elevations persisted for seven days or more in some participants.
So an unaccustomed or unusually heavy session in the week before a blood draw can produce a liver panel that looks alarming and means nothing about your liver.
The two markers that tell you which tissue it came from
This is the practical part, and it is genuinely useful.
GGT is not present in skeletal muscle. Gamma-glutamyl transferase comes from the liver and biliary tract. So if ALT and AST are up while GGT sits comfortably in range, the enzymes almost certainly came from muscle rather than liver.
Creatine kinase confirms it. CK is overwhelmingly a muscle enzyme and rises sharply with muscle damage. A markedly raised CK alongside raised AST and ALT, all moving together, points firmly at muscle. If CK is normal and the transaminases are still high, that explanation is gone.
How to read the pattern
- ALT/AST high, GGT normal, CK high – muscle origin. Very common in lifters. Retest after a real rest period.
- ALT/AST high, GGT also high, CK normal – this is a liver signal and needs proper assessment.
- Bilirubin rising, ALP and GGT high, itching or jaundice – this is the cholestatic pattern typical of 17-alpha-alkylated oral steroid injury. It is the one that needs medical attention promptly, not a supplement.
- Everything high including CK, plus feeling genuinely unwell – do not try to interpret it yourself.
One simple change that makes your bloods readable
Do not train hard in the 48 to 72 hours before a blood draw, and avoid a brand-new or unusually heavy session in the week before. Standardise it: same rough training state each time you test. A number is only useful if it is comparable to your last one.
If you are monitoring liver function during or after oral steroid use, a panel that includes ALT, AST, GGT, ALP, bilirubin and albumin tells you far more than transaminases alone. Adding CK removes most of the ambiguity.
What the numbers do not tell you
Two honest caveats. First, normal transaminases do not prove a healthy liver – fatty liver frequently runs with entirely normal ALT and AST, which is why it is usually found on ultrasound rather than bloodwork. Second, the serious structural complications associated with prolonged steroid abuse, such as peliosis hepatis and hepatic adenoma, are not reliably reflected in enzyme levels at all. A clean panel is reassurance, not a guarantee.
This article is information, not medical advice. Interpret blood results with a doctor who knows your training and your full history.
Other things that move these numbers
Before concluding anything from a single panel, it is worth knowing how many ordinary factors shift transaminases. Training is the big one for lifters, but not the only one:
- Alcohol, which raises GGT particularly and removes your cleanest muscle-versus-liver discriminator.
- Recent viral illness, including ordinary respiratory infections.
- Common medications – paracetamol at sustained high intake, NSAIDs, some antibiotics, and isotretinoin.
- Fatty liver, which is extremely common and often produces mild elevations independent of anything else you are doing.
- Rapid weight loss or prolonged fasting before the draw.
- High-dose supplements, including some pre-workouts and fat burners containing green tea extract at concentrated doses.
None of that means a raised result should be ignored. It means one result in isolation rarely answers the question, and a trend across two or three properly standardised tests answers it much better.
A realistic monitoring approach
If you are going to monitor, monitor properly – a random panel once a year tells you very little. What makes the data useful is a baseline taken when you are not doing anything unusual, then repeat panels under comparable conditions.
- Get a baseline before starting anything, in a rested state.
- Repeat during use and again several weeks after stopping, so you can see whether values return toward baseline.
- Keep the same lab where possible – reference ranges and assay methods differ between labs, which makes cross-lab comparison unreliable.
- Record your training state alongside each result. A number without that context is much harder to interpret.
- Include GGT, ALP, bilirubin and albumin, not just ALT and AST. Albumin and bilirubin say something about liver function; transaminases only report leakage.
The pattern over time is the signal. A single flagged value in isolation is usually noise.
References
- Pettersson, J., Hindorf, U., Persson, P., et al. (2008). Muscular exercise can cause highly pathological liver function tests in healthy men. British Journal of Clinical Pharmacology, 65(2), 253-259. DOI: 10.1111/j.1365-2125.2007.03001.x
- Bond, P., Llewellyn, W., & Van Mol, P. (2016). Anabolic androgenic steroid-induced hepatotoxicity. Medical Hypotheses, 93, 150-153. DOI: 10.1016/j.mehy.2016.06.004
- Nasr, J., & Ahmad, J. (2009). Severe cholestasis and renal failure associated with the use of the designer steroid Superdrol (methasteron): a case report and literature review. Digestive Diseases and Sciences, 54(5), 1144-1146. DOI: 10.1007/s10620-008-0457-x
- LiverTox: Clinical and Research Information on Drug-Induced Liver Injury. NIDDK.
