If you only pick one exercise, choose high-intensity interval training. The secret to keeping your body youthful may be found in the way you move. A new study has found that high-intensity interval training (HIIT) can essentially stop cellular ageing in its tracks and, in some cases, rejuvenate the cells that repair damage in the body. For the study, researchers from the Mayo Clinic took 36 men and 36 women split into younger (aged between 18 and 30) and older (aged between 65 and 80) age groups. The participants were then assigned a three-month programme of HIIT, strength training or a combination of the two. They already knew that both HIIT and strength training provided enormous health benefits to our bodies, they just didn't know exactly how or why, or which was better. So, to understand the way exercise affects us at a molecular level, the researchers then took biopsies from the participants' thigh muscles and compared them with samples from sedentary volunteers. The strength