Comparing mean muscle activity betwen different exercises and time interval lengths

[Brian Horsak]

Dear all,

we are actually conducting research on thorax muscle activation (obliquii ext & int, rect. abdominis and quadratus lumborum) during different core stability exercises to determine mean muscle activity. Aim is to determine which exercises yield highest muscle activies per exercises.

In other research we used a metronome to achive quasi similar rates of motion between all exercises and it was quite simple to standardize movement time intervals and speed. We now try to compare muscle mean activities between exercises with different lengths in time intervals, because it is not possible to standardize all exercises to the same metronome beat. I know that time normalization may be a possible way to overcome this problem, but I´m also aware that it will have an influence on the data.

I would like to have some other opinion about how to process this data - when mean muscle activity between different time intervals is compared (where differences are more than 20% between tasks)?

Many thanks,
Brian

[Ton van den Bogert]

Re: Comparing mean muscle activity betwen different exercises and time interval lengt

Brian,

I was just discussing a similar issue with a student the other day, and we concluded that it might be best to look at the peak muscle activity rather than the mean or the integral of the EMG envelope. The peak should be much less sensitive to the fact that different exercises have a different duration. To increase the reliability, you can average the peak values from multiple repetitions of the same exercise.

Ton van den Bogert

[Brian Horsak]

Re: Comparing mean muscle activity betwen different exercises and time interval lengt

Hi,

thank you for your opinion! We were also thinking of using peak values, and averaging those for at least three trials ... thats probably one good solution.

Regards,

Brian