Friday, 17 February 2012

Infimetrics, Isometrics and Logical Strength Training

It's been a while since I've blogged, and while that is partially due to my absence of good time management, it is also because I've had nothing to blog about....

Until now...

I was recently forwarded the embedded video by James Steele, a colleague of mine here at Southampton Solent University. I'm not showing it because I am in favour of it completely, but simply because the commentator is using a logical approach to training muscles. Which is the fundamentally the most essential part of everything we do. Watch it, and have a think, feel free to comment.

The other thing that this video has prompted is some novel ideas in my own training that I wanted to share. You likely know from my blogs that I am an advocate of slow, controlled movements, normally utilising resistance machines for a single set to muscular failure. However, I chose a different approach to a leg session a matter of hours earlier today.

We are blessed with a clinical MedX Knee Extension machine (see picture) here in one of the labs (which by the way is about as good as knee extension machines get), which in it's function is capable of isometric testing. (Isometric testing might best be described as locking the joint at a specific angle and measuring the force applied to the pad by attempting to move the joint normally - in this example a shin pad is locked in place with your knee at a pre-determined angle through the range of motion, and then the subject attempts to extend the knee with maximal force, this force (torque) is registered on a computer screen by way of a strain gauge).

MedX Knee Extension
So from the video it occurred to me that ultimately our goal in resistance training is to recruit as many muscle fibres as we can in a given part of the body to stimulate muscular growth (e.g. strength and/or hypertrophy) and also reap the rewards that resistance training has on the rest of our physiology.

[On the off-chance you're not clear on fibre recruitment and this principle please read Carpinelli's BRILLIANT article here!)

So for my workout, I chose to lock the machine at a given angle and apply maximal force.....for a while. Of course the muscle fibres fatigue and as such the force produced diminishes gradually, but essentially what we are seeing is that the effort remains constant irrespective of the force production. This is clearly the main goal of training our muscles. This being the case I elected to work maximally for about 90 seconds. No movement. No external forces, such as momentum. No rest phases or sticking points. Plain and simple. Knowing that I was always applying maximal effort to the pad. James Steele was on hand to provide some feedback reporting the force every 10-15 seconds as it decreased and of course encourage me (thank you!).

I elected to do 3 different angles ranging from near full knee flexion to near full knee extension. Each contraction phase was 1 minute long. That's 3 minutes of MAXIMAL work on my quadriceps whilst James watched the force decrease progressively to around 10% of my starting force.

When was the last time you did 3 minutes of MAXIMAL work on your quads. Phew. We're in the process of developing ideas as to more practical applications of this but essentially you need a joint locked in place and you need to be applying maximal force (which is the major limitation with any kind of isointertial exercise).

Anyway, I know isometrics is nothing new, but I thought I'd fill you in on that one. If you have any ideas how to progress it or apply it, or any other thoughts please feel free to comment below.

Be Well



  1. Quick question, and possibly not the wisest of ones either, however, if you were to take lets say a bar for push ups, had the bar locked out at full extension for 1 min, then 3/4 down and subsequently at half way point - then would it be your arms failing or your chest?

  2. A bar for you mean bench press?

    Firstly; locking the bar for 1 minute at the top would do very little except place stress on your elbow joints. When locked our muscles aren't seriously activated. Slightly unlocked for 1 minute would be fine, and so forth.

    In answer to your question though, I don't know. In reality we're all different so we can't really say without doing the test. My suggestion would be that smaller muscles would fatigue first (e.g. deltoids) but that's not necessarily true.

    The problem with this comparison is it doesn't start with maximal force so you might not recruit as many motor units, and thus muscle fibres, as possible; that is when using a weight you can hold for any significant length of time. If you went heavy then you wouldn't necessarily fatigue the smaller motor units. Personally I am a big advocate of negative or negative accentuated training.

    Try it and find out!

  3. @Ginodb

    James is right, there are a number of factors that will determine the fatigue rate of the different muscles invovled and its impossible to make the call without testing it on an individual basis.