To think if I run 30-40 km I should have a toned bum?

[imnotinterestedthanks]

I run 3-4 times a week approx 10km each time. This includes tempo and interval training so I really get a sweat on and don't just go at a steady pace. I am slim, but my bum is pretty flabby despite the exercise. What am I doing wrong? What more do I need to do?

Running should tone your bum if you are doing it right...running is why humans evolved bums!

Make sure you engage your bum muscles as you run. Running up hill/up steps helps you feel which muscles you should be using.

Running using your bum and core should also make you more efficient and faster, so I have been told

Wow, thanks everyone. I am inspired to do some specific bum exercises. How many reps of squats etc do you do and how often? I am pretty clueless.

Is it on a treadmill? If so that's why.

Hill running will give you an arse akin to a pro bulgarian squatters.

(Fyi Hill running on a treadmill will not, the motion of the treadmill pulling your foot backwards prevents full engagement of the muscles unless you're focussing on them at the same time or some bollocks)

If your clueless go to the gym and get a couple of sessions with a trainer to show you how to do it, very few people can just squat with good technique without being shown.
The gym I go to is £15 a month and when you join you get three free half hour sessions for a trainer to show you what to do. That’s a nationwide chain.

I also have an app called SWORKIT. It's free and you can choose bum specific exercises and how long you have to work out. It guides you through them with videos of how to do it. You can then add weights and bands to those exercises. May be worth having a look