Hip and groin mobility work is often overlooked and can contribute to low back issues, knee issues and compensations when doing squatting / deadlift work.
Incorporating movements such as the Frog Stretch into your warm up can help these areas.
When first doing this, be careful though as you will be stretching out some delicate muscles!
• Start on hands and knees
• Bring knees out wide to the side, to the point where the insides of your trainers can lay flat on the floor
• Lower yourself down onto your elbows. This is the start position
• Rock the hips back towards the heels as far as you can go (this will likely stretch some delicate muscles so go easy to begin with)
• Once the hips are as far back as possible, rock them forward to the start position
• This is one repetition, repeat for desired reps.
This is my, mostly, Personal Trainer musings and information which I hope you'll find helpful!