How to get back in shape -- fast

Reneged on your new Year's exercise resolutions? Planning to rush back to the gym for swimsuit season? You're not alone: at gyms across the country, the spring rush is getting under way. Here are some new workout trends to look into.

Rowing. For those who enjoy rowing but don't have the discipline to go it alone, Rowbics, a 50-minute full-body fitness class on rowing machines, is spreading to gyms nationwide. It includes calisthenics and stretches to give a workout for all muscle groups and burns more calories than spinning. See rowbics.com for more info and locations.

Semipersonal trainers. Bally Total Fitness (ballyfitness.com) is introducing a new series of classes manned by two or three personal trainers who walk students through dozens of different stations, maximizing their workout. The gyms are offering these classes free of charge on Thursday nights in an attempt to help gymgoers get a partial personal-training session if they're not yet ready to make a full commitment.

Shorter classes. Thirty-minute workouts have been around for years. But now there's an even less time-consuming option: 15-minute classes. The 24 Hour Fitness chain (24hourfitness.com) offers miniclasses such as Amped Abs that allow gymgoers to focus on specific areas with more intensity. People have flocked to them, and the chain is now looking to add more options, such as a 15-minute jump-rope class. Now you can't say you don't have enough time to hit the gym.