sprints, spread throughout a week can improve aerobic fitness and blood-sugar control. Evidence is building that the HIIT approach to exercise can substantially improve aerobic fitness while providing a range of positive health outcomes, including better blood-sugar control, blood pressure and blood vessel function in a range of conditions such as obesity, metabolic syndrome, diabetes and heart disease. These studies have challenged current thinking regarding how much exercise is needed to produce substantial health benefits. This has important implications for those who decide a 20-minute lunch break is insufficient for worthwhile exercise, or for those looking to make the most of their precious gym time. Mass participation Meanwhile, exercise physiologists and healthcare providers are keenly awaiting much-needed, large scale randomised control trials on HIIT to be funded and carried out. Those studies will give us the evidence to challenge current exercise recommendations and allow the incorporation of HIIT into the standard recommendations needed to treat and prevent chronic metabolic and cardiovascular diseases in the future. While exercise preferences no doubt vary among individuals, and HIIT may not appeal to everyone, HIIT offers a solution for those with little time to be active. Nigel Stepto is Senior Lecturer, Exercise Physiology at Victoria University. He receives funding from NHMRC and the Australian Governments Collaborative Research Network Scheme. He is affiliated with Exercise and Sport Science Australia and PCOS Alliance of Australia. Chris Shaw is Research Fellow, Institute of Sport, Exercise and Active Living at Victoria University. He has received funding from BUPA