good alternative to lunges?

good alternative to lunges?

Are you using them correctly? Because seriously, the amount of weight / reps you ought to be able to handle with straps should be plenty to allow you to get in your lunges (assuming you don't have some sort of hand injury, etc.).

You could also try lifting hooks.

Short of that, Barbell squats or Smith Machine Split Squats, hack squats, or just extra sets of your other exercises should suffice.