Knee injuries among young people are on the rise as social media 'runfluencers' wheel out generic training programmes that push beginners too hard, physiotherapists warned.
Kurt Johnson, director of physiotherapy company One Body LDN, said running injuries had gone up by 100 per cent in the last five years.
The most common injuries are knee problems, he said, like 'runners knee', iliotibial band syndrome, patellofemoral pain, and different tendinopathies.
Shin splints, ankle sprain, achilles tendon problems, hip pain and lower back pain are also on the rise.
A record 1.1 million people applied to the London Marathon this year, with the number of runners in their twenties more than doubling compared with last year.
It coincides with a boom in TikTok runfluencers who sell training courses and publicise aspirational lifestyles, who promote running streaks or even tell people to continue running while injured.
They do this without accounting for differing levels of fitness or types of injury, which could be made worse by doing this.
Young people see these influencers 'posting videos and clips online to look cool, different or healthy, and they want to do the same', but underestimate the physical toll of running, Mr Johnson said.
A record 1.1 million people applied for the London Marathon this year. Meanwhile, runfluencers have been booming on TikTok and running injuries have skyrocketed
@thebigboyrunner told his fans he runs through his injuries to prove to himself he can push 'beyond the pain'
Another 'runfluencer' Sebastian Zeikman told his 21,600 followers to 'just run through the pain bro'
He told The Times: 'The ego can overrun doing the boring basics, starting off slow, etc.'
Some of the courses are 'terrible' and amount to 'a money grab or grift' that ends in injury, he said as he called for better education around the issue and warned runners not to trust everything they see online.
Some influencers have even been encouraging viewers to run through pain and injury, which could end up worsening damage that needs rest.
One TikTokker @thebigboyrunner, told viewers: 'Why am I still running even though I have an injury?
'Does it hurt? Yeah. What keeps me going is knowing I can push myself beyond the pain. Pushing through hard times. And that's why I run, to prove to myself I can.
'And nobody can tell me to stop running, except for me. And that's why I've been running for 948 days straight, no matter what.'
Another running influencer Sebastian Ziekman posted a video of him sprinting at the end of a race with the text 'Pain is temporary, results are forever' over the footage.
The caption read: 'Just push through the pain bro'.
Even beginner schemes could cause problems for those with existing injuries or low fitness levels, Mr Johnson said.
Moving rapidly from inactivity to intensive marathon training has spiked recently and has led to the massive increase of running-related overuse injuries he has seen, like runner's knee, shin splints and back pain.
But Mr Johnson was quick to not discourage those looking to get into long-distance running, saying that it was not dangerous if it was approached properly.
Progressing from no exercise to marathon running is a gradual experience with a lot of preparation necessary through strength training, sleep regimenting, hydration, and nutrition.
The Daily Mail has contacted TikTok for a comment.