&gt; The problem I have seen with intervals training is that few people really go all out.<p>Just because the duration of high-intensity interval exercise is short (maybe 10-20 minutes vs 45-60 minutes), it doesn&#x27;t mean it&#x27;s easy.  In my experience, this is the most difficult type of exercise to do because of the amount of mental conditioning it requires to push yourself that hard, especially beyond the first couple of intense intervals.<p>Like the commenter above stated, many people do not go all out enough to get the maximum desired benefit.<p>What&#x27;s new here in this study is how little or how few intense intervals may be required to get a large benefit, which may make it more attainable.