There&#x27;s two ways to make exercise more strenuous: increase the load&#x2F;intensity, or increase the duration&#x2F;volume.<p>So practically speaking for HIIT, if the premise here was you went &quot;all out&quot;, you can&#x27;t possible go more intense than &quot;all out&quot; because you gave a max effort. So the only other variable to fix is to do more of it.