I can't find the post, so I'll quickly recap.
First, nicotine is a vasoconstrictor. So it may reduce blood flow/circulation.
But, theres a lot more negatives that affect muscle gain than just that. Read on..................
Nicotine also effects the hypothalamus-pituitary axis.
Nicotine stimulates the release of ACTH (adrenal corticotropic hormone..which increases cortisol release).
Acute nicotine consumption stimulates prolactin levels.
And nicotine increases the hormone arginine vasopressin, which may in part be while nicotine acts as a vasoconstrictor.
Next, Nicotine acts on the adrenal axis, stimulating the production and release of glucocorticoids (cortisol).
Nicotine also stimulates an increase in epinephrine (adrenalin).
While these hormones are good during exercise, post exercise they delay the recovery process (i.e: inhibit protein and glycogen synthesis).
Additionally, nicotine stimulates the sympathetic nervous system, furthering the rise in catecholamines (adrenalin), and increased heart rate and vasoconstriction.
While smoking does not seem to affect total testosterone, it does increase estradiol and SHGB (thus, may reduce free test). It also seems to decrease sperm motility.
One of the chemicals in smoke (thiocynates) inhibits thyroid production; however the effects of cigarettes on the thyroid is a bit confusing. Some studies have shown increased thyroid hormone production while others have shown reduce...and yet, some have shown to effect at all. Either way, correct thyroid levels are important to muscle building as too much or too few will reduce protein synthesis.
Smoking may also affect beta cells in the pancreas, especially in men. Smoking has been shown to promote insulin resistance, either by affecting insulin producing cells or via elevated stress hormones, or both.
And as you may or may not know, insulin signalling is one of the most anabolic events in our bodies.
Finally, cigarette smoking reduces gastric emptying time. The reason many drink a shake post workout is to deliver protein and cho quickly into the blood stream to signal protein synthesis, recovery, and growth. So, smoking may reduce the "window of opportunity".
In conclusion....quit!
Br
