Hi Wanda,

Higher velocity requires higher forces, so the emg activity should be higher (maybe not linearly) if they perform longer steps. But other possibility is to increase walking cadence (steps/minute) which influence on time of gait phases, then probably maximum value could be higher too, but I'm not sure about mean value of amplitude or area (IEMG).

I think good option is using percentage value of velocity or better normalised velocity - Vn=Vreal/sqrt(g*Leglength), when you can use effect of leg length.

Best,

Greg

Hi Greg,

thank you very much.

Warm Regards,

Wanda

Dear Wanda,

Several things but for exemple :

Article : VO(2) and EMG activity kinetics during moderate and severe constant work rate exercise in trained cyclists. Christophe Cleuziou, Stephane Perrey, Fabio Borrani, Anne Marie Lecoq, Daniel Courteix, Philippe Germain, Philippe Obert

Canadian journal of applied physiology. 01/2005; 29(6):758-72.

Article: Constant-rate-high-intensity exercise and EMG. P. Germain, C. Cleuziou, R. Halin, O. Buttelli, Z. Taoutaou, P. Obert

Science & Sports 02/2003; 18(1).

Possibilities to be dowloaded with my RG profile.

I am open to a collaboration.

Best regard

If you are using surface EMG, the signal is effected by a number of factors. EMG is considered to be strongly related to tension under isometric conditions and generally EMG studies use a maximal voluntary isometric contraction as a normalizing factor. When the muscle is allowed to shorten, the fact that electrical activity (EMG) is related to the amount of cross-bridge cycling means the interference pattern of the wave will become larger. The fact that you are apparently using surface EMG on leg muscles, you provide yourself with another confounding factor - the cyclic nature of some muscles changing from shortening to lengthening contractions which will also effect the interference pattern of the wave.

Increasing force of the muscular effort, velocity of shortening, total amount of shortening, etc. would tend to result in larger deviations in the interference pattern of the waveform. Reduced muscular effort, velocity of shortening, total amount of shortening, or a change from a shortening muscle action to a lengthening one would tend to diminish the amount of deviation of the interference pattern of the waveform. In a lengthening muscle action as velocity increases muscle activity increases up to a point, while in a shortening contraction this may be a confounding situation because of the force -velocity relationship with muscle shortening.

It appears from the titles of his referred works, Dr. Germain has experience with these issues in the study of cyclists, however he has an advantage you would not have; with cycling he can control force and velocity very accurately, with race walkers accurately quantifying force, velocity, work, and power would present another set of issues, unless you are using laboratory systems, which do not accurately reflect the actual demands of race walking. Research has shown that treadmill walking is actually a skill, slightly different from walking, therefore a sport like race walking with specific gait characteristics would require more of a field test rather than a laboratory test.