From the 12-3-30 workout to the the 75 Hard Challenge, there’s no shortage of fitness methods with quippy numbers-focused names. One that’s been making the social media rounds in recent months is ...

Sometimes you just want a slow and gentle workout, and other times you’re ready to kick it up a notch and pump up the volume. High-intensity interval training, or HIIT, refers to short bursts of ...

Lindsey Ellefson is Lifehacker’s Features Editor. She currently covers study and productivity hacks, as well as household and digital decluttering, and oversees the freelancers on the sex and ...