Sometimes you can't reach your muscles.

What the Sam Hill does that mean, you might ask? Why am I cluttering up your Friday morning with such poppycock?

By this I mean that sometimes it's not possible to exhaust--or really "work" your muscles simply because the brakes are on (Due credit, this is an Alwyn Cosgrove notion, but it's something I've also become increasingly aware of lately).

The most common brakes I've encountered--and hang on a couple of sentences, clarity is coming--are core activation and central nervous system (CNS) fatigue.

Consider: Joe lifter has lousy core strength. So when he squats, his core dies before his legs really get 'worked.' His legs never get sore from squatting.

Hypothetical #2: Olivia never gets enough sleep, and she's always stressed and exhausted. Nevertheless, she dutifully hits the gym several days a week, but it seems like no matter how hard she works, it's rare that her muscles really get a workout, and she's almost never sore. She can't really ever power through a tough set because her muscles just seem to 'turn off' at a certain point.

She also finds that she can sometimes lift a certain weight for rep after rep, but if she increases the weight by just a few pounds, suddenly it's impossible to lift even once. She can't mobilize her nervous system to activate the fibers necessary for the heavier lift.

Do either of these scenarios sound familiar?

The core strength/squatting thing has gotten some air time lately, most notably in Mike Boyle's line-in-the-sand declaration that back squatting is BAD. Boyle contends that the core (in particular the lower back) ALWAYS exhausts prior to the legs. I'm not sure that's always true, as I've seen some "Born to Squat" types with fire-hydrant physiques and huge legs who never seem to drift forward more than a few degrees when they squat, but it may be true more often than not, especially with people who are over, oh, five-foot-two.

But there are other exercises for which a lack of core strength can be a brake as well: deadlifting, bent-over rows, some types of lunges, perhaps overhead pressing and power movements.

When I'm fresh, I can usually eke out an extra rep or two past the point at which my muscles are burning. Typically I don't go to absolute failure, as I have a life to lead and a one-year-old to chase, but I'll certainly approach my pain threshold. When I'm tired and cranky, however, it seems like there's a CNS governor on my muscles that doesn't allow me to approach real intensity, so I don't get much of a muscular workout. I notice this in my hard-driving clients too, who sometimes don't really understand that that whole "eight hours a night" thing ain't just an arbitrary number.

The solutions are pretty cut and dried: work your core--but do so at the end of your workouts, so that you're not sapping your  limited core strength before you hit your big movements; and, of course, get sleep. I don't see much benefit in trying to power through an intense workout when a person is already frayed; it seems more useful to stick to easier movements, stretching exercises, and Feldenkrais drills, all of which can help clear the CNS "static" rather than adding to it.

Have a good weekend!

Andrew