Intensifying the Exercise. Do 3 sets of 15 repetitions . To really challenge yourself with a difficult routine, do 3 sets of 15 vertical leg crunches, with a brief pause in between sets to keep your muscles working.
Intensifying the Exercise. Do 3 sets of 15 repetitions . To really challenge yourself with a difficult routine, do 3 sets of 15 vertical leg crunches, with a brief pause in between sets to keep your muscles working.