Peripheral and central effects of smokeless tobacco on exercise endurance in men

Introduction A proliferation of nicotine use in the sport environment has been observed in recent years mainly as smokeless tobacco (Zandonai et al., 2013). Nicotine has been listed in World Anti-doping Agency’s Monitoring Program from 2012 to 2015 in order to detect potential patterns of abuse. The aim of this study was to investigate the effects of Snus (SS), an oral smokeless tobacco, on the perception of fatigue during aerobic exercise to TTE. Methods The study was a double-blind placebo controlled (SP) crossover design. Fourteen healthy male non-smokers were recruited. Subjects were studied during three sessions on cycle-ergometer: experimental session 1 (Exp1) consisted in an incremental exercise test to determine maximal aerobic power (Wmax); Exp2 and Exp3 consisted in exercise at 65% Wmax until exhaustion in SS or SP conditions. During the Exp2 and Exp3, muscle and cerebral oxygenation by means of NIRS (nearinfrared spectroscopy) and global rating of perceived exertion (RPE) were recorded. Before and after all experiments, the Profile of Mood of State questionnaire (POMS) was administered to subjects. Subjects were then tested by means of Transcranial Magnetic Stimulation (TMS) to assess changes in cortico-motor excitability due to the prolonged exercise. Results Time to exhaustion (TTE) was not significant difference (64.4 ± 41.5 min SS; 51.6 ± 17.2 min SP) (19.2%) in paired Student’s t-test. RPE in the first 30 minutes during both of the sessions showed a significant difference after 10 minutes from start exercise. POMS questionnaire values did not show any significant differences under both conditions (SS, SP). We found significant differences in the cerebral and muscular tissues oxygenation levels in the first 30 minutes of the exercise during SS and SP tests. In particular, at cerebral level, tissue oxygenation index was significantly larger in SS than in SP from the 10th to 30th min of exercise. Conclusion The study showed that the SS effect, compared to placebo condition, could not be an improvement of fatigue during an endurance exercise until exhaustion despite of an increase in tissue muscular and cerebral oxygenation. These data supported the hypothesis of a major activity induced by nicotine as a central stimulator (Mundel and Jones, 2006). References Mundel T, Jones DA. (2006). Effect of transdermal nicotine administration on exercise endurance in men. Exp Physiol, 91, 705- 713 Zandonai T, Baraldo M, Franceschi L, Zappamiglio T, Chiamulera C. (2013). Effects of smokeless tobacco (snus) administration on exercise endurance in men. SRNT Annual Meeting Boston MA (USA) p 165