"Hey Dan. I hope you are doing well. I really enjoy reading your blog and I try to keep up a good fitness regimen. We have a class at my gym called body pump. I'm sure you have heard of it. We work each muscle group for 5 minutes or the duration of a song. The weight used is not super heavy, but by the end of the song it is torture. Do you think this is beneficial or is heavy weightlifting and smaller reps better? I'm looking to lose body fat. Any advice is so appreciated!"
First of all, the most important factor to be successful with any strength training program is to be consistent. A group exercise class like Body Pump is popular, especially with women, because of the motivation provided by a good instructor and comraderie of a large group. That helps consistency. Combined with a healthy diet (like using my Food Rules), most people should see some improvement in body fat levels. And diet gets more important the leaner you get.
A group strength training class like Body Pump does have many limitations which may or may not be evident to most people. These include: lack of individualization, low-level progressive overload, and ineffective training stimulus for non-beginners. Classes simply are 'keep up with the instructor'. Exercises are predetermined and may not be effective or safe for you. The instructor does not have the ability to provide feedback more than simply encouragement to keep up with her. I work with each client one-on-one or in a small group to teach them, assess them, and correct them. In fact, this is a large part of what I do during each session. Clients who I have worked with more than a year still may need some verbal cues or reminders from time to time to ensure they are using good techniques. Also, based on a client's history or assessed needs different exercises or progressions are put in their programs. This is fairly common. None of this can be done in a large group or bootcamp setting.
Progressive overload is key to continually improving with any strength training program. Group strength training classes usually use lighter weights (2-15 pound dumbells or barbells). While beginners can see strength improvements with lower-moderate levels of resistance (40-60% of the maximal weight they can lift one time, termed one-repetition maximum), non-beginners (more than six months experience) will not see any improvements (though, you may be able to maintain) in strength, muscle mass, and metabolism. You must use heavier resistance (60-90% of your one-repetition maximum) to reach long-term strength training and body fat goals. HEAVY STRENGTH TRAINING WILL NOT MAKE YOU DEVELOP BULKY MUSCLES- that is nonsonse. I have measured hundreds of women and they all have seen a decrease in body circumferences. In fact, some of the leanest and lightest women are the strongest. Those 15 pound weights may actually be only 10% of your one-repetion maximum for some exercises like squatting, deadlifting, rowing, and pressing. I have women, on a daily basis, deadlifting and squatting over 100 pounds and pressing more than 50 pounds overhead and some are doing dips and pull-ups with their bodyweight! And the best part is that they are asking for the heavier weights.
Group strength training classes focus on motivating beginners to strength train. This is good. These classes can help you lose body fat if combined with a healthy diet. But, the class is geared to helping beginner women make short-term gains (one to two months). They don't prepare you for long-term success. I imagine most women drop in for a month or two at a time and then drop out (we know the statistics of exercise adherence is extremely low). They never get beyond that beginner level. They are always starting over. In order to be successful (strong, lean, and healthy) long-term you have to build a strong foundation. This includes assessing an individual (watch them perform basic exercises and how they move and walk, or run), teaching them proper technique, progressing a client appropriately, and varying exercises, resistance, sets, reps regularly (periodization). This prepares individuals make long-term (body fat or strength and performance goals).
While a Body Pump workout can be challenging, it is because of its endurance/metabolic demands. That is, light weights are used ( which I mentioned doesn't provide a good strength, muscle, or bone mass-building stimulus to non-beginners) with higher reps and little rest. This actually will help your endurance as much or more than your strength if done consistently for a while. Still the elevation in metabolism wouldn't be close to heavy resitance training. Group training classes get people exercising, which I am all in favor of, but to reap the full benefits of long-term strength training you really need to invest in learning proper strength training principles and free-weight techniques. Once you do, you will see that there is no comparison between a group fitness class or bootcamp and proper, scientifically-validated, strength training. I feel, regular, heavy strength training is the best way to fight aging and the body fat gain everyone experiences with aging. Also, like many of my female clients you will enjoy it, look forward to it, and miss it when you don't get to do it on a regular basis.