similar to those usually observed with aerobic exercise. Dangers of HIIT The American College of Sports Medicine suggests consulting one's doctor before starting a HIIT regimen, particularly if there is a history of coronary heart disease. This is to ascertain its safety and allow the patient to build up the intensity of exercise without causing harm. It is advised to start a lower intensity and go at one's own pace. There is a risk of injury due to fatigue and overtraining, so it is advised to allow time for recovery. Research from Rutgers University demonstrated that the knees, shoulders, and ankles were the most commonly involved injuries. More specifically, knee and ankle sprains were very common. Based on that, neuromuscular training and pre-strengthening programs are recommended to improve flexibility, particularly before exercise. Research A 2007 study examined HIIT's physiological effects on fat oxidation in moderately active women. The participants in the study performed HIIT (defined as ten sets of 4-minute cycling bursts at an intensity of 90% VO2max separated by 2 minutes of rest) every other day over a 2-week period. The study found that seven sessions of HIIT over a 2-week period improved whole body fat oxidation and the capacity for skeletal muscle to oxidize fat in moderately active women. A 2008 research study found that HIIT was more effective than moderate-intensity continuous training at lowering fasting insulin levels (31% decrease and 9% decrease, respectively). A 2017 study examined the effect of HIIT on cognitive performance among a group of children. The authors show that HIIT is beneficial to cognitive control and working memory capacity when compared against "a blend of board games, computer games, and trivia quizzes" and that this effect is mediated by the BDNF polymorphism. They conclude that the study "suggests a promising alternative to enhance cognition, via short and potent exercise regimens". A 2019 clinical trial assessed the effects of HIIT on vascular health in inactive people and found that HIIT has beneficial vascular effects, based on observed decreases in arterial wall thickness and increase in endothelial function. The trial also found that HIIT had stronger effects than medium intensity continuous training (MICT) in enhancing flow mediated dilation and lowering pulse wave velocity in inactive adults from the greater blood flow and vasodilation of blood vessels stimulated by HIIT. Increased flow mediated dilation allows for greater opening of an artery and increased blood flow, allowing