SO accustomed are we to sportspeople making a comeback after having previously announced their retirement that there was no great shock when Michael Phelps stated that he was digging out his goggles and getting back in the pool having retired from swimming after the 2012 Olympic Games.

In London, Phelps became the most decorated athlete of all time having garnered a total of 22 Olympic medals, 18 of them gold.

Eighteen months later, in April of this year, the 29-year-old announced he was to come out of retirement with the aim of adding to his medal tally at the Rio Olympics in 2016. But the honeymoon feeling did not last long. Last week, the American was arrested in Baltimore for driving under the influence of alcohol and has subsequently been suspended for six months by USA Swimming, as well as banned from competing at the World Championships in Russia next August. Almost immediately, Phelps said that he was "deeply sorry" and announced that he was to take a break from swimming in order to attend a six-week rehab programme to address his drinking.

This is not the first transgression by the so-called Baltimore Bullet. He had been arrested for drink-driving once before, in 2004, and served a suspension from USA Swimming in 2009 after he had been pictured using a marijuana pipe.

Phelps is an interesting individual. Clearly one of the most talented and dedicated people to have taken part in competitive sport, he also appears to have a self-destruct button within all-too-easy reach. When the aim is to win eight gold medals at an Olympics, as he did in Beijing in 2008, or to add to his tally at London 2012, he is able to focus on the job in hand. But without a quantifiable goal he seems easily distracted, lost even.

Phelps seems to be a classic case of a sportsperson who thrives on adhering to a regimented, almost monastic, athlete's lifestyle, yet one who, intermittently, fails to resist the temptation to carry out an act that puts the whole enterprise at risk. For Phelps to make a comeback with 22 Olympic medals already in his trophy cabinet screams of someone who does not know quite what to do with himself outwith the bubble he is used to inhabiting.

This is not uncommon. Just last month, Katherine Grainger announced her comeback to rowing after a two-year sabbatical following her gold-medal-winning display in London despite having - on the face of it at least - little to gain. Martina Hingis is back on a tennis court despite several retirements and Phelps' fellow legend of swimming, Ian Thorpe, attempted an ultimately unsuccessful comeback prior to the London Olympics.

In the aftermath of London, Phelps added his name to the long list of those who have realised that they prefer their life as an athlete to anything that retirement can offer. Yet, a return to training was not enough to prevent Phelps from erring. All three of the American's significant misdemeanours have happened during swimming's off-season, strengthening the theory that he likes and perhaps needs to either be bound by a rigid regime or be released from it altogether when the routine permits a release.

A phenomenon such as Phelps has a laser-like focus, which is exactly what brought him such success in the pool. But it is this narrow focus that leaves many sportspeople unequipped for a life outside of the discipline of training and competing in elite circles.

Retirement from sport has been likened by some to death, so hard is it to cope with, and it explains why so many U-turns are performed. But Phelps' case illustrates why it is so important for elite athletes to have outside interests, to have a part of their life which resembles normality throughout the course of their career. It appears that he has been denied something he feels naturally inclined towards. Phelps' coach, Bob Bowman, recalls a conversation with his swimmer after the 2004 Olympics during which he lamented the fact he was "just not normal". Bowman replied, "That's right, and isn't that awesome?"

Phelps appears not to agree and without an all-consuming goal on his horizon, seems susceptible to diverging from his high-performance path. It remains to be seen whether the most successful swimmer in history will return again, and whether he will add to his medal haul in Rio. But, more than anything, Phelps' story illustrates how those who achieve the most can be the most flawed. To achieve what he has achieved requires something special that sets him apart. But whatever powers his greatness may also be what causes him to fall.