AICAR and Exercise-Mimetic Research: What the Science Says

AICAR is often labelled an “AICAR peptide”, but it is actually a small molecule, also called acadesine, that activates AMP-activated protein kinase (AMPK), the cell’s energy sensor. AICAR and exercise-mimetic research took off in 2008, when sedentary mice ran further after four weeks of treatment. Human studies of acadesine cover other conditions, and none we found tested it as an exercise substitute. 

What is AICAR?

AICAR is a synthetic nucleoside analogue and a small molecule, not a peptide. A peptide is a chain of amino acids, whereas a nucleoside is a sugar joined to a base. The full chemical name is 5-aminoimidazole-4-carboxamide ribonucleoside, and its clinical name is acadesine.

Many people call it an “AICAR peptide” because the compound is sold and discussed alongside research peptides. The label is a misnomer, but it is often how people first come across the compound. Cells also make a phosphorylated form of the molecule naturally, and the U.S. Anti-Doping Agency (USADA) notes that its accumulation is associated with metabolic disorders in humans. 

The naming is looser than it looks. Strictly, AICAr (lowercase r) refers to the riboside, which is acadesine, and AICAR refers to the phosphorylated form, also called ZMP. Most papers and suppliers use AICAR for both. The rest of this article uses AICAR for the compound sold and studied as acadesine. 

Inside cells, adenosine kinase converts it to ZMP, which resembles AMP. A 2021 systematic review in Cells sets out the convention and how widely the compound has been used in the lab. 

How AICAR activates AMPK 

What AMPK does

AMPK works like a fuel gauge. When a cell’s energy supply drops, AMP rises and AMPK switches on, and the cell shifts toward burning fat and glucose. Training activates AMPK in this way, as the 2008 Cell paper that popularised the exercise-mimetic idea points out.

AMPK acts in several tissues. The introduction to a 2008 human study in Diabetologia summarises its reach. AMPK increases glucose and fatty acid uptake and oxidation in muscle, reduces glucose output from the liver and restrains the breakdown of fat tissue.

How AICAR switches AMPK on

AICAR bypasses the energy drop. ZMP imitates AMP, so AMPK switches on without the cell running short of fuel. That is the principle behind the term exercise mimetic. Fan and Evans (2017) define an exercise mimetic as a compound that produces some of the effects of fitness, such as remodelling of mitochondria, the structures that make a cell’s energy.

AICAR and exercise-mimetic research: the 2008 mouse study 

The idea took shape in a 2008 paper in Cell from the Salk Institute (Narkar et al.). The team gave sedentary mice daily AICAR for four weeks. In a treadmill test, the treated mice ran about 44% further and about 23% longer than untreated mice, and the study reported that AICAR switched on metabolic genes in their muscle. The full text in Cell gives both figures.

The result popularised the term “exercise pill”, which later reviewers criticised. The mice in the treadmill experiment, however, received daily injections, according to the paper’s methods. The 2021 Cells review also reports that AICAr showed very poor oral bioavailability in clinical trials. The 2008 paper reported that a second compound, given alongside training, raised endurance further. The study was in mice and measured treadmill endurance, so it says nothing directly about health outcomes in people.

What else have animal and cell studies reported?

Later studies applied AICAR to other tissues. Claims about AICAR peptide benefits often rest on studies like these, which report effects in animals and cells, not established benefits in people. The table summarises four of the studies, with the main limit of each. 

The common thread in these studies is AMPK in animals. They show the pathway can be switched on and that tissues respond. They do not show that people respond in the same way, or that any response is useful.

What the brain study showed

Guerrieri and van Praag compared AICAR with running in mice over three, seven and 14 days. By day 14, AICAR no longer increased new cell numbers or neurotrophin levels in the hippocampus. It also raised the activity of genes linked to cell death and of an inflammatory signal called interleukin-1β. The authors concluded that only running consistently benefited the brain. 

What have human trials tested? 

Acadesine has been given to people in clinical studies, but for other purposes. The table lists what was tested and what was found. 

Heart surgery: A promising result that needed confirming 

The cardiac programme shows why promising results need confirmation. The 1997 pooled analysis suggested a benefit. RED-CABG was a confirmatory trial in intermediate- to high-risk patients, enrolling between 2009 and 2010. A pre-planned interim analysis found a very low likelihood of a statistically significant benefit. The trial stopped after 3,080 of a planned 7,500 patients (see the trial registry entry and the American College of Cardiology’s summary).

Has acadesine been tested for exercise? 

None of the published human studies we found tested AICAR as an exercise substitute or measured exercise performance. The 2008 mouse result has no human counterpart. 

Why “mimics exercise” is harder than it sounds

Fan and Evans describe physical exercise as the best solution and treat muscle-targeted mimetics as a possible pharmaceutical alternative for people with a sedentary lifestyle. Three findings complicate that idea:

• AICAR is not a clean switch. The 2021 Cells review found that many AICAR effects once credited to AMPK are AMPK-independent. It also notes that ZMP is 40 to 50 times less potent than AMP at activating the enzyme and accumulates at high concentrations in the cell.
• Exercise acts on far more than muscle. Hawley, Joyner and Green (2021) call the terms “exercise pill” and “exercise mimetic” a misnomer. Compounds studied so far have mainly targeted skeletal muscle and fail to reproduce many of exercise’s effects in other organs, and no single “exercise gene” or pathway exists.
• Timing and tissue change the result. The muscle-wasting study reported protection when AICAR activated AMPK early in disease, while AMPK activation that comes later through metabolic stress may contribute to wasting. The brain study found the response reversing within two weeks.

AICAR in sport: WADA and UKAD rules

The World Anti-Doping Agency lists AICAR under S4, hormone and metabolic modulators, as an AMPK activator. The 2026 Prohibited List came into force on 1 January 2026. USADA states that AMPK activators are prohibited at all times, in and out of competition, because of their potential performance-enhancing effects.

UK Anti-Doping (UKAD) applies the WADA list to sport in the UK. USADA also states that AICAR is not approved for therapeutic use in humans anywhere in the world, which is a health risk in its own right.

AICAR for research use at River Peptides 

River Peptides supplies AICAR for in vitro laboratory research only. It is not for human or veterinary use. Every batch is sent for independent testing by third-party laboratories, including Janoshik and Analiza Biatek. High-performance liquid chromatography (HPLC) confirms purity and mass spectrometry verifies identity. Browse the AICAR (50mg) research compound to see its full specification. 

AICAR research Frequently Asked Questions

Is AICAR a peptide?

No. AICAR is a synthetic nucleoside analogue and a small molecule, not a chain of amino acids. People often search for it as an AICAR peptide because it is sold and discussed alongside research peptides. 

What is the difference between AICAR and acadesine? 

They are the same compound in everyday use. Acadesine is the clinical name used in the cardiac and leukaemia trials, and AICAR is the name most research papers and searches use. Strictly, acadesine is the riboside (AICAr), and AICAR is its phosphorylated form, but most papers and suppliers use AICAR for acadesine. PubChem lists the compound under both names.

Is AICAR banned in sports?

Yes. WADA lists AICAR under S4, hormone and metabolic modulators, and USADA states that AMPK activators are prohibited at all times. UKAD applies the same list in the UK. 

Does AICAR work as an exercise mimetic in humans? 

The exercise-mimetic result comes from mice. The human studies of acadesine we found covered heart surgery, type 2 diabetes and leukaemia, not exercise performance. Hawley, Joyner and Green argue that the term “exercise mimetic” overstates what any single compound can do. 

Is AICAR approved for any use? 

USADA states that AICAR is not approved for therapeutic use in humans anywhere in the world. The large cardiac trial RED-CABG was stopped early for futility. 

Is AICAR safe and what are its long-term effects?

AICAR is not approved for therapeutic use in humans anywhere, and USADA describes it as a health risk for that reason. The human studies of acadesine used short intravenous infusions in clinical settings, and the leukaemia study reported an acceptable safety profile at the doses tested. In mice, the 14-day brain study found the response reversing, with higher activity of genes linked to cell death. We found no long-term human safety data, and this article gives no guidance on use. 

What is AMPK?

AMPK, or AMP-activated protein kinase, is an enzyme that works as a cell’s energy gauge. It switches on when energy runs low and shifts the cell toward using fat and glucose. Research summarised in Diabetologia describes its role in muscle, liver and fat tissue.