In a time crunch? Try this workout for abs
If you want to flatten and firm your abdominal muscles without having to do an endless amount of crunches, include this move in your workout routine. Your arms will act as resistance and will challenge your core muscles to maintain proper spinal and pelvis alignment. Be sure you focus on precise form for best results.
1 Sit upright on a flat, nonslip surface with your knees at 90-degree angles, hip-width apart. On an exhale, press your navel toward your spine and begin curling back. Reach your arms forward so your fingertips touch your knees. Slide your shoulder blades down and away from your ears. Keep your shoulders above hip level, with the abdominals flat and contracted.
2 Keep your navel pressing toward your spine as you slowly raise your right arm until it is near your right ear. Pause for a moment, then switch arms, raising your left arm to your left ear. Do not release your abdominal muscles or change the position of your back during this part of the move. Continue switching arms until you have done 3 to 6 raises on each side. Reach both arms to your knees again and return to the upright position to release your abdominals. Repeat twice.