At the onset of a muscle contraction, the presence of calcium triggers the opening of the Na-K channels in the membrane. Potassium is a calcium inhibitor, so as the potassium flows out of the cell, it eventually reduces the presence of calcium. This causes the closure of the Na-K channel (negative feedback mechanism). In a hypokalemic state, the lack of sufficient K doesn't inhibit the calcium channel, and in turn doesn't properly terminate the muscle contraction at the cellular level.
1.the diaphragm. hope it helps
The three minute step test involves stepping up and down on an 18-inch step for three minutes, at a rate of 24 steps per minute. The recovery pulse is then counted for 30 seconds after a one minute rest.
The Rockport walk test is performed on the treadmill, encouraging the participant to walk as fast as they can control for one mile. The workout time and heart rate are recorded at the mile mark and compared against standard averages.
