On easy days, when the coaches wanted an effort level of 1.5, the athletes instead ran at an effort level of 3.4 on average. On hard days, conversely, the coaches asked for an effort of 8.2 but ...

TikTok users are doing 100 kettlebell swings a day for 30 days to burn fat and sculpt their bodies. Here's what the challenge does to your body, per trainers.