The effect of cannabis on regular cannabis consumers' ability to ride a bicycle.

To assess the effects of cannabis on the ability required to ride a bicycle, repetitive practical cycling tests and medical examinations were carried out before and after inhalative consumption of cannabis. A maximum of three joints with body weight-adapted THC content (300 µg THC per kg body weight) could be consumed by each test subject. Fourteen regular cannabis-consuming test subjects were studied (12 males, 2 females). In summary, only a few driving faults were observed even under the influence of very high THC concentrations. A defined THC concentration that leads to an inability to ride a bicycle cannot be presented. The test subjects showed only slight distinctive features that can be documented using a medical test routinely run for persons under suspicion of driving under the influence of alcohol or drugs.

Comparison of venous blood alcohol concentrations and breath alcohol concentrations measured with Draeger Alcotest 9510 DE Evidential.

Most comparisons of blood alcohol concentrations (BAC) and breath alcohol concentrations (BrAC) are either derived from drinking trials with rigid drinking protocols or from investigative authorities' data with considerable time differences between the determination of BAC and BrAC. In general, only comparisons of relatively low BAC-BrAC pairs are available. Therefore, the relationship between BAC and BrAC was examined even for high BAC above 2g/kg. The results of a large-scale drinking test under realistic conditions with 78 test persons and short time intervals between BAC and BrAC measurements are presented. It was shown that the conversion factor Q varies greatly (between 1571:1 and 2394:1) and increases with increasing BAC. A constant conversion factor that is suitable for variable forensic purposes could not be presented.

The effect of alcohol hangover on the ability to ride a bicycle.

To investigate the effects of alcohol on the ability to ride a bicycle, practical cycling tests were carried out at different blood alcohol concentrations (BAC). For this purpose, various alcoholic beverages could be consumed from around 2 p.m. until 11 p.m. Afterwards, the test persons spent the night on the trial site and were provided with dormitory sleeping accommodation. On the following morning, beginning at around 8 a.m., a final cycling test was performed. The performances of those test persons who had returned to state of soberness and of those with residual blood alcohol levels were compared to the performances on the day before. The practical ability to ride a bicycle was significantly reduced in the postalcoholic state compared to the rides of the day before. The relative cycling performance in the postalcoholic state was comparable to the rides under the influence of BAC of around 0.30 g/kg. There were no remarkable differences between the groups with and without residual blood alcohol levels regarding the rides on the next morning. Therefore, it can be assumed that the direct influence of residual blood alcohol levels plays a minor role for the ability to ride a bicycle in the postalcoholic state. Instead, the side effects of the high amounts of alcohol that were consumed the night before are crucial.

Differences between male and female cyclists' performances under the acute influence of alcohol.

To examine the effects of alcohol regarding the fitness required to ride a bicycle, practical cycling tests, accompanied by medical examinations, were carried out at different blood alcohol concentrations. Seventy-eight persons were included in the trials (41 males, 37 females). Eighty-three evaluable trials were obtained. Men committed less coordinative driving faults with comparable blood alcohol concentrations. Single highly alcoholized men were able to safely ride their bicycle; however, each of the female test persons had at least one severe driving fault at blood alcohol levels above 1.43 g/kg. Women tended to exhibit signs of alcoholization in the medical examination reports earlier than men.

Regarding the fitness to ride a bicycle under the acute influence of alcohol.

To determine the threshold for the absolute inability to ride a bicycle, practical cycling tests and medical examinations at different blood alcohol concentrations were performed. Special attention was given to additional medical examinations, reaction tests and alcohol consumption under real-life conditions. Seventy-eight test subjects were included in the trials (37 females, 41 males). Five test subjects participated twice; thus, there were a total of 83 evaluable trials. Alcohol-related deficits were already identifiable at very low BACs. A significant increase in gross motoric disturbances compared to the soberness state did not regularly occur until a BAC of at least 0.8 g/kg was reached. At the BAC of 1.4 g/kg and above, no test subjects were able to achieve or surpass their sober driving results. Isolated highly alcoholised test subjects rode the bike in a manner that was not conspicuously different than the other sober test persons. Contrary to the assumptions of current German legal practise, it cannot be stated that all people are 'absolutely impaired' to the point of being incapable of riding bicycle at BACs of at least 1.6 g/kg.