If available, you can use a cable machine for this exercise.
Alternatively, fix a strong resistance band to a solid object at knee height.
Step one leg forwards to assume a stride stance position.
Slightly rotate your trunk away from your front leg with your hands down towards your rear hip, holding the band r handles under moderate tension.
Maintain a neutral spine and engage your deep abdominal and shoulder blade muscles throughout this exercise.
When ready, push off your front leg to step backward and simultaneously rotate your trunk in the opposite direction as you bring your leading arm into a 90/90 position with your thumb pointing up and back.
Your other hand will follow.
Pause, then return to the start position with control.
Repeat, leading forwards with your other leg, rotating the other direction.