The effects of oral smokeless tobacco administration on endurance performance

Background: Smokeless tobacco is widely used by athletes to enhance performance. Nicotine is a central nervous system stimulant and acts on cardiocirculatory and metabolic systems, involving tissue blood flow and circulatory vasoreactivity. The aim of this study was to investigate the effects of the oral smokeless tobacco(Swedish snus(SS)) on the perception of fatigue and time to exhaustion(TTE) during moderate-intensity aerobic exercise.Methods: Fourteen healthy non-tobacco male users were recruited for a double-blind, controlled crossover design(SS vs. snus placebo(SP)).Subjects were tested for 3 sessions: experimental session 1(Exp1) consisted of an incremental test to determine the maximal aerobic power output(Wmax), whereas Exp2 and Exp3 consisted of exercising at 65%Wmaxuntil exhaustion in SS or SP conditions. During Exp2 and Exp3, muscle and cerebral oxygenation was assessed by means of near-infrared spectroscopy, and the rating of perceived exertion(RPE) was recorded.Results: Comparing SS with SP tests, significant differences(p < 0.05) were found in the values of cerebral(～3%) and muscular tissues oxygenation(～4%) in the first 30 min of exercise. The RPE values were not significantly different between the 2 conditions(SS vs. SP). No significant difference was found in TTE(SS: 54.25 § 21.84 min; SP: 50.01 § 17.03 min).Conclusion: This study showed that muscular and cerebral oxygenation increased significantly with snus administration during an endurance exercise until exhaustion, but this did not affect fatigue perception and TTE. The results showed that snus could not be considered an ergogenic substance in non-tobacco users.

Combination of Instrumented Nanoindentation and Scanning Probe Microscopy for Adequate Mechanical Surface Testing

The elastic indentation modulus and hardness of standard bulk materials and advanced thin films were determined by using the nanoindentation technique followed by the Oliver- Pharr post-treatment. After measurements with different loading/unloading schemes on chemically polished bulk titanium a substantial decrease of both modulus and hardness vs an increasing loading time was found. Then, hard nanostructured TiBN and TiCrBN thin films deposited by magnetron sputtering （using multiphase targets） on substrates of high roughness （sintered hard metal） and low roughness （silicon） were studied. Experimental modulus and hardness characterized by using two different nanoindenter tools were within the limits of standard deviation. However, a strong effect of roughness on the spread of the experimental values was observed and it was found that hardness and elastic indentation modulus obeyed a Gaussian distribution. The experimental data were discussed together with scanning probe microscopy （SPM） images of typical imprints taken after the nanoindentation tests and the local topographyls strong correlation with the results of nanoindentation was described.