POLLY SWANN is agitated.

Confined to the gym at the Team GB rowing training centre at Caversham Lakes in Berkshire, the 23-year-old's focus should be on her rehabilitation from a troublesome back injury, but, instead, her thoughts will drift inexorably towards this weekend's second World Cup event in Lucerne and the fortunes of her colleagues in the women's eight competition.

Questions cloud her consciousness. How will they do? Will they row better without me? What happens if the girl in my seat impresses? Is this injury going to cost me a place at the Olympics? It might be her physical capabilities that are currently under examination but the Edinburgh native's mental faculties are also undergoing strenuous scrutiny.

Swann is one of 14 girls, along with compatriot Lindsey Maguire, competing for eight places in the Olympic boat. A further two will go as reserves, with the remainder instead joining the European Championship squad. Her chosen degree subject at Edinburgh University might be medicine but it is arithmetic that dominates her thoughts. "If I'm honest, I freak out every now and again about it but I've got to believe that I will be in the team because, if I don't, nobody else is going to," she says.

Such concerns are heightened by the injury that flared up while on a training camp in Italy at the end of April. Given the propensity of rowers to suffer back pains, Swann initially thought little of the discomfort but, as the session continued, she realised something was seriously wrong and retired to the physio room. A bulging and dehydrated disc was diagnosed. "I had to have an epidural where they injected steroids into my spine . . . that was nice," she recalls, wincing.

The pain has, so far, been worthwhile. Having spent a couple of weeks restricted to fitness work – she missed the first World Cup event in Belgrade – she has been permitted back on to the water in recent days and is building up intensity ahead of her reunion with the rest of the squad upon their return from Lucerne on Monday.

With testing to determine selection for the Games looming, her return is timely. "It's still a little bit in my mind that I maybe won't row this summer because of the injury but I think I'll be okay," she says. "It's a pretty big mental burden to deal with and negative thoughts do fly around but it's important I focus on all the good things I've done this year and how much I've improved; two or three weeks off isn't going to take that away."

Swann's philosophical bent is perhaps informed by experience, her introduction to rowing actually having come as a consequence of back trouble. As a pupil at George Heriot's in Edinburgh, her ambitions as a hockey player were ended by such discomfort at the age of 14 and, having enjoyed sailing, she dubiously reasoned that rowing might be to her liking, too.

She discovered a talent for the sport and was invited to trials for the junior GB squad only for more back trouble – caused by the inability of her still slight frame to support her height (6ft 1in) – to hinder her progress. The passing of a few years, and subsequent development of muscle, allowed her to row recreationally at university and earn a place in the coxless four at the under-23 World Championships in 2010. "I enjoyed that and, on the flight home, I asked Nick Strange [now coach of the Olympic womens's eight] if it was worth me giving rowing a shot. I thought I had more potential to fulfil but I wanted to hear it from someone in authority."

Within weeks, she had arranged a sabbatical from her medicine degree and moved to Henley-on-Thames, whereupon she established herself as a contender to assume one of the more technical positions in the octet – stroke or No.2 – this summer. Should she fail to be selected, it will not be for lack of effort. Swann arrives at the lake at 7.30am most days and is on the water by 8am for a session that normally runs to 24km. A two-hour break in which she eats a second breakfast, visits the physio or psychologist and does video analysis with her coach is followed by a further stint on the water, with a weights session in the afternoon. "Then we're free to go home and sleep . . ." she says.

Given the repetitive nature of the training, does it not get boring? "It can be monotonous, yeah, and that's one of the big things to overcome," acknowledges Swann. "You need to break out of the sessions becoming a box-ticking exercise because you can so easily switch off and, before you know it, you've done 10km and are halfway through without engaging with it.

"As a group, we want to be the best so we can't afford to just let our bodies take over; you are striving for that elusive, perfect stroke every single time and that is exhausting mentally as well as physically but it is what you have to do if you want to win an Olympic gold."