ISLAMABAD (APP) - One of the world's leading drug sport scientists claims some Olympic athletes are turning to Viagra, laughing gas and even tattooing in the latest dirty efforts at winning gold. Former Australian Institute of Sport researcher Robin Parisotto said athletes are experimenting with inserting their drugs of choice through tattoo needles, Melbourne's Age newspaper reports. Research in Germany has shown that delivering DNA vaccines in this method was 16 times more effective than injecting through the muscles or veins as the vibrating tattoo needle prepares the body's immune system and increases the body's response to the drug.  "The problem is that some of the drugs would now fly under the radar with the tattoo technique because athletes would be taking a much smaller dose," Dr Parisotto was quoted as saying. The author of Blood Sports: The inside dope on drugs in sport said cheating athletes are also combining Viagra with doses of nitrous oxide, or laughing gas. Both drugs increase the flow of oxygen in the blood stream and therefore boost sporting performances. Dr Parisotto even warned of the new exercise pill recently shown to enhance the running time of mice. "With some of these things the technology is so new, the concept so bizarre, that there would only be a handful of well tapped-in athletes using it but they will be experimenting at the Beijing Olympics because it is the ultimate," he said.