View Full Version : EMG and MVC

04-14-2003, 08:13 PM
Dear Colleagues,

I am an Honours student trying to understand what is the best way to examine
EMG within subject’s results. My study involves performing plyometric (drop,
countermovement & continuous) on hard ground and a rebound surface. I have
been searching the Biomech-L archives and also have been in contact with two
renowned researchers in Australia. Each has a different view on what is the
best way to normalize EMG data.

Firstly one of the researchers states that isometric contraction is the way to
go whereby performing knee or hip flexion for RF, supine leg surl or hip
extension for BF, Standing Calf raise for GAS, Seated calf raise for SOL.

However the other researcher states that there are so many issues that varies
between an isometric and dynamic muscle activity. For example different join
angles for isometric MVC will result in different muscle lengths and therefore
different EMG signals. In the other case dynamic muscle activity uses peak
EMG activity displayed by a muscle during a set jogging pace to normalize the
EMG displayed by the same subject in a jump, which is said to be

This researcher however has another way of looking at EMG. This other way
involves using the muscle activity in one activity as 100% and report
variations of the EMG signal relative to this %. Example use peak EMG during
drop jump as 100% and then report the countermovement jump activity for the
same muscle relative to that 100%.

So what I would like to ask is for comments to the above ways of normalization
for EMG data (pros and cons) please……………..

A summary will be posted…

Thanks in advance for your time,


Robert Crowther
Honours student
Institute of Sport and Exercise Science
James Cook University
Ph. (07) 4727 7433
Email: Robert.Crowther@jcu.edu.au

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