Runners often obsess about numbers; from PBs to average pace to racing weight, numbers can be important. However, here are some running stats that might just surprise you.

1. Around 70 per cent of runners will pick up an injury

If you are currently injured, it may be of small consolation to know you are in good company. The American Academy of Physical Medicine and Rehabilitation researchers have come up with a running injury stat which suggests that around 70 per cent of runners will sustain an injury at some point. Knee injuries are considered the ones most likely to occur, but other injuries which affect runners include Achilles tendinitis , shin splints and heel pain.

To lessen the chances of getting injured runners should ensure they have the correct running shoes for them. A good warm up and cool down is important, and introducing cross-training to do activities other than running allows the body to recover from the effects of running. Gradual progression is key and a good structured training plan can aid this.

2. Running up to 20 miles a week helps you live longer

While it is commonly accepted that running is generally good for health, going too far and running too much could adversely affect your life expectancy. Researchers at the University of South Carolina and the Ochsner Health System in New Orleans say that running a maximum of 20 miles (over 32 km) per week can help you live longer. In their study they looked at 53,000 people, all of whom had a clean bill of health at the start of the study, and found that runners had around a 20 per cent lower mortality rate than non-runners during the course of the study.

However, before you all think of turning into Forrest Gump and hitting the road, the study suggested that up 20 miles per week is the magic number and that runners should not exceed this amount if they want to maximise the life-lengthening benefits of running. The research showed that the risk of premature death was lowered for those runners who ran no more than 20 miles or no more than five times per week, whereas the risk increased for those running more frequently and over greater distances.

3. A third of female marathon runners will experience breast pain

While runners have more than enough injuries to worry about, female runners also have to consider the impact their breasts may have during a race. A study published in the British Journal of Sports Medicine, suggested that around a third of female marathon runners will experience breast pain. The study focused on the exercise habits of 1,300 women who were planning on running the London Marathon, and found that 1 in 3 of the those questioned said they had experienced breast pain and that 1 in 6 of them said the pain affected their exercise.

Not surprisingly those with larger breasts were considered more likely to experience pain and that sports bras (which were worn by 90 per cent of the women) did not always help. The research suggested that the design of sports bras still needs improving, but that ladies should choose a bra with maximum support and ensure they are measured frequently, as it is suggested that more than 7 out of 10 women are wearing the wrong size bra for them.

4. The world record for the number of consecutive marathons is 607

Completing a marathon is often one for the bucket list and many who do it swear ‘never again’, not running man Ricardo Abad though. Between October 2010 and May 2012 Ricardo set an amazing running world record by completing 607 consecutive marathons - that’s an unbelievable 15,903 miles (or 25,593km).

Impressive stuff you might think, but what makes it all the more impressive is that Ricardo set his record while combining his running with a daily 8-hour shift in his full time factory job. Despite his crazy schedule, Ricardo even managed to achieve an impressive personal best of 2:46 in one of his runs.

5. One fifth of people don't have the 'marathon gene'

The marathon attracts people of all shapes, sizes and abilities, and it is perhaps from this that has strung the belief that anyone can run one as long as they train properly. However, while it may be true that most people could complete a marathon, research suggests that 20 per cent of people genetically would be incapable of running a marathon in a good time, even if they dedicated plenty of time to training properly.

Researchers at the University of Loughborough found that the ability to run a marathon in a good time requires a specific combination of genes, which nearly one fifth of the population simply don't possess. According to the researchers, those without this combination of genes will struggle to improve their performance no matter how much they dedicate themselves to training.

The reasoning for this is because this one fifth of people have muscles which don't extract as much oxygen as runners with this right mix of genes, and intensive training can actually further reduce their body’s ability to carry oxygen to their muscles. The researchers suggest that these runners would be better served by building up their strength and muscle tissue in the gym.