• high dose β₂ agonists such as salmeterol
  • clenbuterol
  • oral albuterol
  • testosterone
  • terbutaline

High dose beta-2 agonists

Performance enhancing effects of inhaled medications (2025)

clenbuterol and salbutamol improves immediate verbal recall and delayed recall compared with placebo (ref)

Clenbuterol

increased skeletal muscle mass and protein content (ref, ref, ref)

clen is used for cutting and fat loss too.

Terbutaline

High-dose inhaled terbutaline:

  • increased quadriceps strength and enhanced maximal sprint performance versus placebo (ref)

Formoterol

No bronchodilation benefit

Salbutamol

high-dose oral salbutamol protocols can raise quadriceps/hamstring strength by around 10–20% in some studies (ref)

Salmeterol

Salmeterol is a long lasting beta-2 agonist (LABA).

Bronchodilation - improved oxygen delivery. Larger airway dilation. Reduced airway resistance even in healthy lungs. Slight increase in VO2max. Lower breathing effort. Improved endurance in sustained aerobic activity.

Skeletal muscle - improved protein synthesis, reduced protein breakdown, increase fast-twitch muscle fiber size, improved neural activation of muscle fibers. Measurable increases in strength and power. Modest improvements in sprint speed and explosive performance.

Fat loss and body composition changes - better lipolysis (fat breakdown), slight thermogenic effect. Reduction of fat mass. Improved power-to-weight ratio. Physique improvements.

Stimulant effects - increased alertness, reduced perceived exertion, elevated heart rate, elevated motivation. Short-term feel good or energizing mood. Greater training volume tolerance.

Selective Androgen Receptor Modulators (SARMs)

S23 - extremely high androgen receptor affinity, full agonist in muscle, high anabolic : androgenic selectivity, very long receptor residency, very strong suppression of endogenous hormones.

RAD-140 (Testolone) - very high androgen receptor affinity, no conversion to estrogen or DHT, cognitive effects. Favors muscle/bone tissue. It belongs to the class of aryl-propionamide–based selective androgen receptor modulators (SARMs).

RAD-140 has structure: 2-chloro-4-{[(1R,2S)-1-(4-cyano-3-trifluoromethylphenyl)-2-hydroxypropyl]amino}-3-methylbenzonitrile (ref)

YK-11 (not a true SARM but often treated like one) (a derivative of 19-norandrostenedione, and partial androgen receptor agonist; also upregulates follistatin, an inhibitor of myostatin)

AC-262,536

Ostarine (MK-2866 / Enobosarm)

LGD-4033 (Ligandrol)

S4 (Andarine)

LGD-3303