1. LACK OF INDIVIDUAL PROGRAMMING
Whereas fun and variety may help ward off boredom, this same lack of consistency from class to class could actually keep you from seeing any results. Since a group workout is, by its very nature, written for everyone (read: not just you), it may fail to address individual differences or weaknesses. For example, someone with a previous shoulder injury performs the same workout as another participant with an ankle injury. Granted, good teachers are quick to provide progressions and regressions for individual cases, but it's often difficult to address each unique situation.
2. LACK OF ATTENTION TO FORM
The motivational benefit of having a crowd of other bodies sweating next to you also has some downsides. With larger class sizes, it becomes difficult for instructors to watch and critique individual performance. This means that, for example, if your form on new exercises is less than perfect, there's a good chance no one will be available to correct you. Although talented instructors give cues both orally and through demonstration, it can still be difficult for participants to nail down a technique—particularly when using new equipment.
3. OVERTRAINING POTENTIAL
Group fitness classes, including many bootcamps, often have a similar "work till you drop" mindset. While this may push you to do a great workout at the time, it's not a sustainable mantra in the long run. In fact, attending too many classes that push you to your limit and beyond may well set you up for a case of overtraining. Since most classes feature a different mix of attendees, it's impossible for instructors to plan for repeat visitors, leading them instead to push each class to go 110%. Eventually, participants may find themselves feeling listless and lacking motivation.
To prevent overtraining, avoid relying solely on group fitness classes as your only method of training. Instead, incorporate them into a well-rounded program that also includes days specifically designated for rest and recovery. You'll see better results and also feel better the next time you hit your favorite group workout.
IT'S YOUR CALL
Group fitness classes certainly offer abundant benefits. The camaraderie and group atmosphere make them far more enjoyable than solo adventures. Instructors also have a knack for pushing you harder than you'd normally push yourself. However, for every benefit, there are also some negatives to be aware of. The group atmosphere makes individual coaching hard to come by. The constant "go hard" mentality can also set a lifter back rather than helping him progress.
To get the best of both worlds, program group fitness classes into your schedule alongside a structured workout routine. That way, you'll reap the benefits of the group experience, while at the same time gaining the success brought by proper progression in your own training.