My thoughts are that you will need some kind of signal processing before the scope input.
An amplifier to amplify (obviously) the small signals from the muscles etc, and some filtering.
A lowpass filter to cut the HF noise above 2000Hz
A highpass filter to cut the LF noise below 20Hz ? Not sure. There maybe useful signal information way down there.
A notch filter to remove 50/60Hz mains supply noise.
Also, a reference input connected to reference electrode on the "patient" which can be used to subtract general noise from the wanted signal, as frequently used in ECG (ElectroCardioGram) type equipment.
How well the Hantek will perform with multiple inputs, I do not know, maybe it will be OK at the low frequencies that you will be measuring.
But without some processing between patient and scope ? ...
Probably no chance.
JimB