The discriminative stimulus, subjective, cardiovascular, and reinforcing effects of nicotine as a function of light physical activity.

Smokers often experience the acute effects of cigarette smoking while they are engaged in the light physical activity of routine tasks. However, virtually all laboratory-based research on these effects is conducted under conditions of quiet rest and, thus, may not generalize to effects in the natural environment. We examined changes in the discriminative stimulus, subjective, cardiovascular, and reinforcing effects of nicotine in humans as a function of the level of concurrent physical activity. Men and women smokers (N = 17) were initially trained to discriminate 20 microg/kg nicotine by nasal spray from placebo (0 microg/kg) at rest. Three sessions then followed, in which the generalization of discrimination was tested across a range of doses (0-20 microg/kg) while at rest or engaged in very light or light physical activity (15% and 30% of heart rate reserve, respectively) via bicycle ergometer. Generalization testing involved both two- and three-choice ("novel" option) quantitative procedures. Self-reported mood via the Profile of Mood States and visual analog scales, and cardiovascular measures of heart rate and blood pressure were obtained concurrent with discrimination responding. Nicotine reinforcement was assessed after the end of generalization testing using a choice procedure under the same rest or activity conditions. Results showed that physical activity did not significantly alter nicotine discrimination or reinforcement, as no interactions between activity and nicotine were observed. When activity and nicotine influenced the same subjective and cardiovascular responses, they acted in a generally additive fashion. These findings suggest that research on the acute effects of nicotine conducted under typical resting laboratory conditions generally are not altered by light physical activity and so may generalize to the effects of nicotine under conditions common in the natural environment.