what is the recommended rep range for exercises in the basic core video–bird dog, hip bridge, leg raises, etc? also how long should one hold a plank, side plank? as long as possible. or some time short of failure, but multiple reps. thanks
Reps for these basic core exercises should be until fatigue hinders perfect execution. Same thing for isometric holds. Once you get over a couple of minutes in these iso holds I recommend adding resistance like a weight vest.