I am sitting on a chair in an empty gym trying to ignore the fact that, a few feet away, a man in a white coat is about to send an electrical charge directly into my brain.

The device I am about to road-test could represent the future of doping, but this is a world away from the tales of unmarked glass phials, corrupt coaches and crooked athletes. Rather than using illicit substances to boost the body, this technology is legal and serves simply to boost the mind.

The theory behind the technology, known as Transcranial Direct-Current Stimulation (tDCS), is that low-level electronic pulses targeted at specific areas of the brain can stimulate them into working either more or less effectively.

From an inauspicious start in the 1960s, when brain implants were used in attempts to ‘cure’ homosexuality, modern techniques such as tDCS have been developed over the past 15 years to treat individuals with severe depression and mental illnesses. Increasingly it has also been used by the US military, including snipers and pilots, and now it is being embraced by the world of sport, with some Rio athletes having taken advantage of it in the build-up to the Olympics.