Protocol

Aim
To demonstrate the effects of stimulating muscle at high frequency.

Unfused Tetanus
The nerve is stimulated (supramaximal voltage) at a frequency of 1 Hz and then the frequency is gradually increased to 10 Hz over a 4 second period. When peak muscle tension is observed, the frequency of stimulation is reduced back to 1Hz.

Fused Tetanus
The nerve is stimulated (supramaximal voltage) at a frequency of 1 Hz initially. The frequency is increased to 10 Hz for 1 second and then gradually to 70 Hz over a 3 second period. When peak muscle tension is observed (a plateau) the frequency is decreased to 10 Hz and then to 1 Hz.

Task
You should observe the muscle response in both experiments and measure the peak tension at 1 Hz, 10 Hz and 70 Hz.

Then try answering the questions.