Effects of smokeless tobacco (snus) administration on exercise endurance in men.

There are anecdotal reports that some winter sport athletes used smokeless tobacco (Snus). However, there are no studies whether this is a socio-cultural habit or a sought psychobiological effect. The aim of this study was to investigate the effects of Snus (SS) on the perception of fatigue during an endurance exercise. The study was a double-blind placebo controlled (SP) crossover design study. We recruited 14 non-smokers (breath CO confirmed) men (age 22.8 ± 4.6 years; means ± SD). Subjects were studied during three sessions on cycle ergometer: experimental session 1 (EXP1) consisted on an incremental exercise test to determine VO2max (maximal oxygen uptake) and Wmax (maximal aerobic power output); EXP2 and EXP3 consisted on SS or SP administration followed by an exercise at 65% Wmax until exhaustion. During the EXP2 and EXP3 the global rating of perceived exertion (RPE) was recorded, using the 15-point Borg scale every 5min until the end of the session. Blood samples were taken in order to assess nicotine plasma levels during the session. Detected plasma nicotine level was 7.31 ± 1.78 ng/ml (means ± SD) in 7 subjects for SS and 3.26 ± 0.12 ng/ml (means ± SD) in 3 subjects for SP. In three subjects nicotine was no detectable. Seven out 13 subjects cycled for longer during the SS vs. SP session: time to exhaustion was 60.4 ± 41.5 min after SS and 48.8 ± 19.4 min after SP; paired Student’s t-test showed that a 18.6% increase was not significant. RPE at 25%, 50%, 75% and 100% of exhaustion time increased during both session; however, no differences were observed between the two conditions. In conclusion, the study showed that SS does not change RPE compared to placebo condition; this means that the sought effect could not be an improvement of fatigue during an endurance exercise until exhaustion