A marathon might seem like a great new goal, but experts are warning that there's a lot that goes into training and race day than some may think.

Over 15,000 runners, walkers and wheelchair athletes took part in yesterday's Auckland Marathon, but the event was overshadowed after six people were hospitalised for cardiac-related issues.

Sports Lab Physiotherapist Vaughan Craddock says there's more interest and participation in marathons in recent years.

He says inadequate training, or taking on too much too soon, can increase the risk of injury.

"Leading into the race, its usually muscular aches and pains, joint injuries like tendon injuries where people have normally started a little bit quick into their training programmes or haven't been able to balance the load as much as they'd like."

Craddock says he sees a lot of muscle sprains, joint and tendon injuries in the lead-up to marathons.

He says as well as bio-mechanics and physical flexibility, many other facts can affect a person's training and race.

"The level of experience would obviously be one. The training level where they are starting at and where they are looking to progress to before the event would be another. Things that we take for granted such as nutrition, sleep, work-life balance, your stress level."

One running coach is urging runners to do their homework before signing up for an event.

Brown says it's important people do the right preparation to eliminate the risk of injury.

"Never underestimate on the day the weather, the course, right through to making sure you are doing the training, and then finally, know your capability on the day."