My muscles are burning--this must be a good exercise, right?

Azdak · January 2011

At the start of the year, when people are more inclined to try new exercises and new exercise products, I thought I'd repost an article I wrote last year on the subject. This is archived at: http://www.myfitnesspal.com/blog/Azdak/view/my-muscles-are-burning-this-must-be-a-good-exercise-right-17697

A key technique used in infomercials for a new "fitness" device is to take the device into a crowd and invite random people to try it out. The viewer is then shown a series of testimonials saying "I could really feel this working" or "my (legs, abs, butt, etc) muscles were burning so I know it really works." Even without an infomercial, some people come to the same conclusion when they try out a new device, a new exercise, or a new class. If you try something and it makes your muscles fatigued, or burn, or sore the next day, it must be effective, right?

Not necessarily. Exercise training effects are very specific. An exercise movement will recruit the muscle fibers necessary to meet the demands of that movement. If one does the same movement over and over, some muscle fibers may became highly trained, while others nearby are trained only a little or not at all. If you engage in a movement that has different demands, then different muscles are recruited and others are activated in different patterns. If the movement is different enough, the muscles may become quickly fatigued, or if it is different and more intense, one might feel a burning--and then fatigue. However, this is an ACUTE response to the immediate demands of the movement--it only means that, at that moment, you were asking these muscles to do more than what they were used to doing. If they weren't doing much of anything before, then it doesn't take much to overload the muscle and cause fatigue.

Fitness (strength and cardio) improvement occurs as a result of the SYSTEMATIC APPLICATION OF A PROGRESSIVE TRAINING LOAD. The body always tries to maintain "homeostasis"--an internal, stable equilibrium. So it will adapt to a training load--but ONLY to the specific demands of that load. Once it adapts, it reestablishes equilibrium and no further adaptation takes place.

So when you are evaluating any fitness product--any device, any shoes, any class, any movement--you have to ask: what is the resistance method? is the resistance method designed so that it is applied effectively? And, most importantly--CAN THE RESISTANCE BE PROGRESSIVELY INCREASED? If the answer to the last question is "NO", then this device, product, etc is probably going to be ineffective and not worth the money.

Even though you may "feel" different muscles working when you do the movement or use the device, if there is no progressive overload, your body will quickly adapt to the "load" and you will no longer see improvement. Of course by then, the "return window" has expired or you just don't bother to send it back, or the power of auto-suggestion makes you think it's YOUR fault that you aren't doing better.

This is especially true of machines that use only body weight as resistance--and use only a small part of the body--and that use a dynamic movement such as gliding, rocking, or a spring mechanism to assist the movement. It is also true of products that contain an inherent “instability” that causes muscles to initially work “differently”, but provide no way to change the instability pattern or increase resistance.

Often the manufacturers will show you "EMG studies" that show the muscles being activated. That's a time-honored smokescreen. All that shows you is the immediate response--it doesn't show the level of resistance and it can't show whether or not there is a training effect.

Examples of these types of products include: Leg Magic, most infomercial ab machines, most "thigh" machines, and “tone up” shoes. (Although some people just find the “tone up” shoes really comfortable—that’s a different issue).

This does not mean that ALL new movements or exercises are ineffective--far from it. Doing a variety of exercises that activate different muscle groups or works them in new ways is important--as long as you can progressively increase the resistance. In that case, if you do a new lifting movement that results in fatigue/burning/soreness, that is often a good thing. That might mean it's an area you may have been neglecting.

kwardklinck · January 2011

Thank you for the information. The further I get into my fitness routine, I realize that while I am fit to do some activities, I'm in terrible shape when it comes to others. I think the best thing we can do for ourselves is continually change up what we do. We need cardio but when the routine gets too easy, we have to find something harder. When your weight lifting routine gets too easy, you need to add weights or intensity to show results. Every activity I do causes fatigue and soreness at first. Even though I've been exercising for over a year now, not all of my muscles have been worked properly.

givprayz · January 2011

Bravo! I just wrote my first ever blog to gripe about the misinformation/useless gadgets that are promoted all over the web and that I see creeping into forum posts. So nice to see a post that is well written and from a knowledgeable source that says what the real fitness gurus have always said, it takes hard work, time, and attention to detail, not a new gadget, to get fit. Again, Bravo!