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.
Read moreIntensifying 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.
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