Sit-ups remain one of the best methods of reshaping the abdomen, second only to standing in front of a cannon. Enjoy explosive exercise with this Groupon.

Choose from Three Options

• $24 for six walk-in classes (up to a $72 value)
• $42 for 12 walk-in classes (up to a $144 value)
• $49 for a six-week outdoor boot camp with two sessions per week (a $300 value). Boot-camp classes are held Saturday at 9 a.m. and Wednesday at 6:30 p.m., with new sessions starting every six weeks.<p>

Classes include the 20-minute Core and More class, which strengthens the body’s center with abdominal and lower-back workouts. During the 45-minute Indoor Cycle class, an instructor leads stationary bikes through hills, springs, and flats as muscle-motivating music inspires pedaling. See the schedule and class descriptions.<p>

Trainers hold the outdoor boot camp just outside the gym at V-Tone Fitness’ outdoor workout facility. Classes challenge students with core work, plyometrics, and weight training, all supplemented by classic exercises such as pushups and jumping jacks. The moderate intensity suits those looking to jump-start an exercise regimen, and trainers demonstrate experienced and beginner versions of each activity.<p>