How To Choose an Effective Training Weight

In New Orleans, Ash Wednesday is the day that people hit the gym in furtherance of their New Year’s resolution. Why bother starting in January when resolutions are impossible to keep with Bowl games, basketball events, king cakes, and whatever else might fill up the time between New Year’s and Mardi Gras.

Folks flock in droves to the gym ready to plunk down some cash on a membership for some strength training and maybe a little cardio**.  If you are in that number but don’t really know what to do once you change into your new Under Armors and hit the gym floor, let me get you started.

How to choose an effective training weight. I’m going to make several assumptions: 1) that you have a life, and don’t want to spend it in the gym; 2) that you want to see results sooner rather than later, 3) that because of 1 and 2 you have decided to try high intensity training*, 3) that you understand that moving slowly rather than ballistically requires greater muscular effort and recruits more muscle fibers, kind of the point of strength training, and 4), that you will perform one set of 8-12 exercises with good form.

So back to the issue of training weight.  Let’s start with the Size Principle.

The Size Principle explains the sequence in which different muscle fiber types contract. Essentially it says that small fibers contract first, then intermediates are recruited, and then large.  Furthermore, slow twitch fibers are enduring and have great recovery ability, fast twitch fatigue quickly and take a long time to recover, and intermediate are somewhere in between. If you choose a weight that’s too light, you’ll never get to the fast twitch.

“If you use a weight that is too light….you will recruit the slow-twitch fibers into service, but because they fatigue so slowly, by the time you have started to recruit the intermediate fibers, some of the same slow-twitch motor units will have started to recover. They will then recycle back into the contraction process, thus preventing you from ever engaging the higher-order muscle fibers.” Body by Science, Doug McGuff, MD, and John Little (2009)

But this doesn’t mean just pile weight on because heavier is better.  While you a heavy weight initially recruits all fibers, the fast twitch give out so quickly that the other two don’t have time to burn. So you want to choose a weight that is heavy enough to take you through all those steps, but not so heavy that it has to skip the first two.

There is a great post on by Chris Highcock who cleverly explains this principle with a parable, one that is hard to forget.

Push starting your car….with friends

Imagine that you find that your car battery is flat.  You need to push start the car.  Luckily your friends are there to help.  They are a strange group though – all athletic but with different skills, different aptitudes.  There are lots of them too; whole families of them in fact.

Continue Reading …

Of course you can’t really “feel” which muscle types are firing.  So a rule of thumb is to choose a weight would leave your muscles exhausted in about 90 seconds, but not before 60.  And without any experience, that weight is may as well be just a shot in the dark. My advice to my clients when they go on vacation or whatever, and will be setting their own weights in hotel gyms:  put a weight on there that’s heavier than you really want to move, but that you think you might be able to maintain for 90 seconds. This will usually give you a good weight that you can work with.  If you go over the 90 seconds with great form, you need a greater challenge.  If you don’t make it to 60, reduce it a bit.

Also, you might want to consult a trainer for a few sessions, just to make sure you’re on the right track.  Most gyms have someone on hand for an extra fee.


*This is just an assumption for my ease, as this is the training I do.  The Size Principles obviously crosses modalities of lifting.

**A subject for another post


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