The brooks racer st 5 running shoe is light enough for shorter distances such as a 5k but sturdy enough to get you through a marathon with its lightweight construction helping you to get your time as fast possible the inclusion of biomogo means that you can revel in long lasting cushioning allowing your legs to stay fresher for longer excellent support with lightweight feel and flexibility come from its midsole construction featuring rearfoot hydroflow st full length biomogo now non toxic an