From the article:
Markers of inflammation increased in the blood and muscle samples of the smoke-exposed group but improved significantly in the smoke-exposed exercise group after the research team introduced the treadmill tests. Both smoke-exposed groups had a lower muscle weight when compared to the control group and showed a decrease in fiber area in the muscles prior to introduction of exercise. Exercise reversed some of this type of damage in the smoke-exposed exercise group. “Regular endurance exercise training seems to protect long-term smokers against some important negative local and systemic consequences of smoking,” the researchers wrote.