Reading research: Comparison of Strength Differences and Joint Action Durations Between Full and Partial Range-of-Motion Bench Press

When I first started strength training, I thought of partial range-of-motion lifts as something to be avoided.  However, as I’ve spent more time reading, learning and experimenting, they have grown on me considerably.

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Why bother with partial lifts?

Well, to be honest, I think there are several good reasons.  The main attraction, of course, is that they allow you to use much more weight than you would do on a full range-of-motion.  However, there are other significant benefits too.

For example, in certain lifts, like the bench press, a partial range-of-motion lift is much less stressful on the shoulders than a full range-of-motion lift.  For lifters with injuries, partials can be a great way to get a training effect while not further damaging a problem area.

And on the deadlift, the use of a partial range-of-motion lift can allow a much higher frequency of training than a full range-of-motion.  Personally, I have found that I can pull heavy from the rack up to three times a week (so far) but pulling from the floor needs at least a week off inbetween, if not two.

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What’s the study?

There is not a great deal of research available on partial range-of-motion lifts but I did come across this short study while I was looking for something else.  It’s not the world’s greatest bit of research, being done with only five subjects, and it doesn’t have any huge revelations.

However, it made me think about partial lifts in a more systematic way, which I found beneficial.

The study is called Comparison of Strength Differences and Joint Action Durations Between Full and Partial Range-of-Motion Bench Press Exercise, by Mookerjee and Ratamess, Journal of Strength and Conditioning Research, 1999.

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What’s the background?

Introducing strength curves

Most people are quite comfortable with the idea that the force that can be demonstrated in a given movement, such as elbow flexion (for a biceps curl), varies depending on where you start the movement.

However, it sounds stranger (but is no less true) to put this concept another way: the strength of the muscle is different depending on where you start the movement.  How can the strength of the muscle change?  Researchers have tried to answer this tricky question and some suggest that the answer can be found in that muscles are stronger or weaker at different lengths (and therefore tensions).  Others have suggested that the answer is simply a matter of engineering moments.

In any event, whatever the mechanism, by measuring the force that the body exerts at different points in the possible range of motion, you can plot the strength curve of the movement, to show where in the movement the muscle is strongest and where it is weakest.

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Manipulating strength curves

Strength enthusiasts have worked out that training the weakest points in a strength curve can allow the sticking points to be removed.  Most people come across this idea when first reading about the techniques used by Louie Simmons and other powerlifters for the bench press.

Here’s big Jim Wendler doing his thing

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Powerlifters claim that board presses allow the lifter to train the weak part of the strength curve and improve the full lift.  (Bear in mind that a bench shirt changes the competition requirements of the full range-of-motion lift and that the end of that range-of-motion is the hardest part of the lift rather than the easiest).

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So what did the researchers do?

The researchers worked with five male strength trainees, whose bench press performance had not improved for some time.

They determined the 1RM and 5RM of the lifters at full range-of-motion and at a partial range-of-motion that corresponded to 90 degrees of elbow angle.  The lifters were able to use weights that were approximately 10 – 15% heavier in this partial lift.

Four days later, the researchers tested the lifters again.

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What happened?

The full range-of-motion bench press did not improve over the four day period.  However, the partial range-of-motion lift improved by c. 5% on average.  The only training done on this lift was the 1RM test followed by the 5RM test.

While this result might appear to be unsatisfactory, as it didn’t improve the full range-of-motion lift, going home with this idea would be a failure of imagination.  The interesting thing is that despite the stagnation that the lifters were experiencing on the full range-of-motion lift, they were still able to improve on a partial lift, because it was new.  They were able to enjoy the benefits of motor learning and the stimulus that comes with something that the body is not accustomed to.

This suggests that if a lifter were to go through a process of elimination by working steadily through a variety of different partial lifts over a period of 3 – 4 weeks, they should eventually hit the point in their strength curve that is weakest.  By improving this point, the full range-of-motion lift should also improve.

Of course, many people will find that the bottom position of a lift is the hardest and it seems odd to consider a partial range-of-motion lift at this point.  However, it is possible to do partial range-of-motions from a bottom position by using a power rack with two sets of pins and by working between those pins.

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Further thoughts

I wish that the researchers had done more partials at different points in the strength curve.  It would be very interesting to see a scientific experiment in which a 3 – 4 week routine of partial lifts could be shown to improve a full lift by working through the strength curve.

However, this would then generate two possibilities.  Either working all the way through the strength curve was the stimulus, or hitting the weak point was the stimulus.  To find the answer to this secondary question, the researchers would then have to do a second round of experiments, in which only the weakest point in the strength curve (as measured by the previous experiment) was trained.

I think that there is real scope for quite a bit of interesting research in this area and, given that there is nothing needed other than a power rack and some pins, there really shouldn’t be anything stopping researchers from getting their hands dirty.  I may even start having a go myself.