TikTok says it’s the ultimate wake-up call. But does the fitness craze have any downsides – apart from waking up the neighbours? TikTok says it’s the ultimate wake-up call. But does the fitness craze have any downsides – apart from waking up the neighbours? I f you’re an avid viewer of online fitness content (or live below someone who is) you’re probably familiar with TikTok’s 50 jumps challenge. The basic premise is simple: you jump 50 times as soon as you wake up, for 30 days straight. Reach