Expired-air CO and puff topography data indicate that, relative to a single cigarette, a single waterpipe tobacco smoking episode is associated with greater smoke exposure. Abstinent waterpipe tobacco smokers report symptoms similar to those reported by abstinent cigarette smokers, and these symptoms are reduced by subsequent waterpipe tobacco smoking. Taken together, these data are consistent with the notion that waterpipe tobacco smoking is likely associated with the risk of tobacco/nicotine dependence.

With subjects standing on a treadmill moving sinusoidally backward and forward, recordings of electromyographic (EMG) leg and trunk muscle activity, head and joint movements and platform torque were made with the subjects' eyes open or closed. The sinusoidal frequency was changed, stepwise and randomly, between 0.5, 0.3 and 0.25 Hz. The amplitude of the deflection was constant at +/- 12 cm. During an adapted sinus cycle, the maximum leg muscle EMG activity was recorded in the tibialis anterior around the posterior turning point and in the gastrocnemius around the anterior turning point in the treadmill cycle. This activity was associated with a forward inclination of the body around the posterior point and a straightening of the body at the anterior point. Both the degree of body inclination and the corresponding EMG activity were dependent upon the sinusoidal frequency. The programmed adjustment of the body inclination was such that the result of inertial and gravitational forces acting on the body coincided with the axis of the body at the posterior turning point. At the anterior point, the adjustment was achieved mainly by strong activation of the leg extensors. The latencies of the compensatory muscle responses to a change in treadmill frequency were significantly shorter at the posterior point for the gastrocnemius than for the tibialis anterior, and at the anterior point for the tibialis anterior than for the gastrocnemius. No correlated changes were seen in the corresponding head and joint movements. The difference in latency can best be attributed to the different body postures during the sinusoid. Early activation of the gastrocnemius is required due to the forward-directed impulse to the inclined body at the posterior point, and of the tibialis anterior muscle due to the backward-directed impulse to the erect body at the anterior point. It is suggested that afferent input from extensor load receptors provides information about the position of the body's centre of gravity relative to the support surface and determines the generation of the EMG responses. Adaptation of both the EMG and biomechanical patterns to a new sinusoidal frequency of the treadmill occurred within four cycles after the change. Biomechanically, this was reflected as a change in the body posture. Vision did not significantly affect these changes. In conclusion, standing on a sinusoidally moving platform, the nervous system acts to control the position of the body's centre of gravity relative to the feet. Body posture is adjusted in such a way that the forces acting on the body during the treadmill movements become minimised.(ABSTRACT TRUNCATED AT 400 WORDS)

Waterpipe tobacco smoking is increasing in popularity worldwide and available evidence point to its addictive and harmful potential. This study is conducted to assess nicotine exposure in daily waterpipe users smoking the waterpipe according to their usual routine. The correlation between nicotine exposure and puff topography parameters has also not been explored systematically. Sixty-one waterpipe tobacco smokers (56 males; mean age ± SD, 30.9 ± 9.5 years; mean number of weekly waterpipe smoking episodes 7.8 ± 5.7) abstained from smoking for at least 24 hrs, and then smoked tobacco from a waterpipe ad libitum in a laboratory setting. During the session puff topography parameters were monitored continuously, and pre- and post-smoking expired-air CO was measured. Before and after smoking, venous blood was sampled for the assessment of plasma nicotine using Gas Chromatography-Mass Spectrometry. Average pre- and post-smoking expired-air CO was 4 ± 1.7 and 35.5 ± 32.7 ppm, respectively (i.e., a CO boost of 31.5 ppm, p < .01). Mean plasma nicotine concentration increased from 3.07±3.05 ng/ml pre-smoking to 15.7 ± 8.7 ng/ml post-smoking (p < .01). Plasma nicotine boost was correlated with total session time (Pearson correlation coefficient r = .31, p = .04), cumulative puff duration (r = .37, p = .01), mean puff duration (r = .34, p = .02), and total smoke inhaled in the session (r = .34, p = .02. These data show considerable nicotine exposure in daily waterpipe smokers, and that nicotine exposure is a function of waterpipe smoking patterns.

This study's objective is to examine the relative effectiveness of cigarettes and waterpipe (WP) in reducing tobacco abstinence symptoms in dual cigarette/WP smokers. Sixty-one dual cigarette/WP smokers participated (mean age ± SD 22.0 ± 2.6 yrs; mean cigarettes/day 22.4 ± 10.1; mean WPs/ week 5.2 ± 5.6). After 12-hour abstinence participants completed two smoking sessions (WP or cigarette), while they responded to subjective measures of withdrawal, craving, and nicotine effects administered before smoking and 5, 15, 30 and 45 minutes thereafter. For both tobacco use methods, scores on measures of withdrawal and craving were high at the beginning of session (i.e., before smoking) and were reduced significantly and comparably during smoking. Analysis of smoking and recovery (post-smoking) phases showed similarity in the way both tobacco use methods suppressed withdrawal and craving, but the recovery of some of these symptoms can be faster with cigarette use. This study is the first to show the ability of WP to suppress abstinence effects comparably to cigarettes, and its potential to thwart cigarette cessation.

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