Methylene Blue and Muscle Hypertrophy

Does methylene blue have an impact on human muscle size?

Methylene blue has been largely established as safe to use in humans but does it have a negative effect on muscle size? This may be important as muscle is the largest metabolic organ we have and plays an important part in glucose regulation. Thus, muscle mass plays a role in keeping glucose and insulin levels in check which keeps us insulin sensitive.

Study: Prostaglandin and myokine involvement in the cyclooxygenase-inhibiting drug enhancement of skeletal muscle adaptations to resistance exercise in older adults, PMID: 23220477

This study look at the effect of taking paracetamol or ibuprofen while resistance training in an elderly population. They found that the drugs (common anti-inflammatories) actually promoted muscle mass and strength gains. "The drug-induced suppression of intramuscular PGE2 production increased net muscle protein balance after each exercise bout through a reduction in PGE2-induced IL-6 and MuRF-1, both promoters of muscle loss." 

IL-6 is a common inflammatory marker in a range of conditions. Many of those in the hypertrophy game believe that reducing inflammation may stymy muscle growth. However, this is showing just the opposite. Perhaps the inflammation created is purely to fix the damage done by a bout of exercise and does not assist muscle growth. If the damage caused by a workout can be reduced, then you may see larger gains as the body uses more of its resources on muscle growth rather than repair.

This shows that anti-inflammatory drugs do not impede muscle growth, at least not across the board. Thus, the argument that methylene blue inhibits muscle growth on the basis that MB is a powerful anti-inflammatory may not be correct.

The difference may be in the type/how the anti-inflammatory effect is mediated (there is a whole host of different inflammatory molecules).

Study: Methylene blue regulates inflammatory response in osteoarthritis by noncoding long chain RNA CILinc02, 10.1002/jcb.27602

The above study states that MB "can dramatically decrease the expression of IL-1, IL-6..".

Study: Methylene Blue Application to Lessen Pain: Its Analgesic Effect and Mechanism, 10.3389/fnins.2021.663650

However, MB also decreases inflammation by suppressing endothelial Nitric Oxide (eNO) expression. 

eNO is a vasodilator, thought to increase recovery by allowing greater blood flow to the muscles. The science on this is wavy.

Taking methylene blue should not have deleterious effect on hypertrophy resistance training. It may even show itself to assist in muscle growth - more research is needed here. Either way, the effect is likely small given the lack of any agreement thus far.