People run for all kinds of reasons: to raise money for good causes, to get fit and healthy, to get away from the rest of the world, and sometimes just to prove to themselves they can. A bomb designed to wreak havoc and take lives is never justifiable; to detonate one at the heart of an event where people have come together for the sheer joy of running seems most especially cruel. Running is often a solitary sport, but if there is any positive to be gained from this week's events, it is the way not only a city came together, but an entire country. People united in one goal: to find those responsible.
Runners are putting their minds and bodies to the ultimate test as they take part in the world's hottest and coldest marathons
Why is hydration important? Around 70% of our body is made up of water; it is vital for every chemical reaction in the body. We need around 2-3 litres a day to transport nutrients, help with cellular enzyme activity and digestion of food, to carry out waste and toxins and also to support brain function for mood, energy and concentration.
Endurance sports have exploded in popularity in recent years, and with the New Year once again upon us, we can look forward to further growth as a new contingent of enthusiasts aim to bypass the fads and make firm resolutions; to pound the pavements.
With an alarming 26% of British citizens male and female classified as obese according to a 2012 NHS report, one would think this summer of sport would be a welcome one. However with such focus on extreme exercise comes the risk of cardiac arrest.
After months of gruelling training runs, 35,000 runners are counting down the hours to reaching the start line at Sunday's