Questions will be asked about his defence, physique and inexperience, but there can be no reservations whatsoever about the raw pace of Carlin Isles, the USA international sevens player who yesterday agreed to join Glasgow Warriors until at least the end of next season.

The 24-year-old winger, commonly known as the fastest man in rugby, has a personal best time for the 100 metres of 10.13 seconds, a mark that would have earned him a semi-final place at the London Olympics.

Coincidentally, it was around the time of the 2012 Games that Isles decided to switch from sprinting to rugby, making an immediate impact on the IRB Sevens circuit.

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Isles has also become an internet sensation, a two-minute YouTube clip of him in try-scoring action having attracted more than five million hits over the last 15 months.

Expected to arrive in Glasgow within two weeks, Isles has scored 27 tries in 14 sevens tournaments for the USA national team. However, at just 5ft 8in and 11st, he is tiny by modern rugby standards, and is believed to have played only a couple of 15-a-side games.

Isles arrives at a time when the Warriors are clearly in need of a new edge in attack. Last season, they collected nine try-bonus points on their way to clinching a RaboDirect PRO12 play-off place. In the current campaign, they have gained none.

Gregor Townsend will be looking to Isles to ignite the side in the way Niko Matawalu did when he first arrived. "This is a major coup for the club and a very exciting prospect," the head coach said. "Carlin is an exceptionally gifted athlete who has picked up the game of rugby in a very short period of time and has had a huge impact on the sevens circuit over the last couple of years.

"He is really eager to learn and develop as a winger in the 15-a-side game. With his lightning pace and evasion skills, he already has an excellent base from which to challenge for a starting place."

Isles said: "I'm up for the challenge. I've been doing a lot of challenges in my life so this is just another obstacle and I'm ready to take it on. Isles added: "I've been in contact with Gregor a few times and knowing he really wants me and sees something in me means a lot."

Meanwhile, the Scottish Rugby Union have announced they are looking for former internationalists to participate in a study of the long-term effects of head injuries.

Dr James Robson, Scottish Rugby's chief medical officer, said: "Concussion is the singularly most important health-care issue in a number of sports at the moment.

"By looking back at our former internationalists we hope to learn how we can look forwards.

"Clearly things have changed over the years in the way we look after and manage players' health but that does not mean we should rest on our laurels."