A. 3-5 rounds not for time
10 kb swings
30 sec rest (5 x Pull-Ups)
15 kb swings
30 sec rest (3 x pull ups)
25 kb swings
30 sec rest (2 x pull ups)
50 kb swings
2 min rest

Scaled:
Instead of 50 swings on your last do 30 swings.

In your rest perform some kind of upper body pull. If you can’t do pull ups, you can do single arm rows. This is tough workout (100 swings if you choose to do 50 in your last ser) wear gloves if you have a pair. Idealy all swings would be unbroken but don’t sacrifice the form especially on the last set. The weight should be something you normally swing or touch lighter.

You can repeat this workouts 3-4 times a week, change the Pull-Ups to press ups or single arm presses. Done correctly you should feel your hamstrings the next day, not your lower back. It will challenge your grip and definitely get you out of breath. Simple but very effective 👍