Build core strength, stability and endurance, not to mention six-pack abs, using the Tabata protocol of 20 seconds of work followed by 10 seconds of rest and recovery for 8 sets. Beginners may want to keep their feet on the floor for most of the intervals. Advanced may want to begin the first bicycle crunch interval at twice the speed and with a weight. Music: In a Heartbeat by Kevin MacLeod, www.incompetech.com
