Jason Derulo works out twice a day, five to six days a week, he told Insider. His favorite exercises for his abs are L-sit pull-ups, weighted sit-ups, and seated rows, he said. Derulo intermittent ...

Many people turn to Pilates in search of a strong core, but a dumbbell core workout is an easy way to strengthen these muscles without pulses and holds. Exercises like planks and sit-ups weighted with ...