An isotonic contraction can be concentric, which is where the muscle shortens as the fibres contract or eccentric, where the fibres contract as the muscle lengthens. When a muscle contracts with no resulting movement, it is an isometric contraction. Page: 1  1. 2  2. 3  3. 4  4. 5  5. 6  Back.
how much propane will i use i will be building an ig pool and ig spa 7ft spa i will be heating the spa with a 400k btu propane heater i would like to heat the pool a couple of time per year for special events local code limits the size of a propane tank to 125 gallons anything bigger will require a permit from the fire dept
How They Work. Gas pool heaters use either natural gas or propane. As the pump circulates the pool's water, the water drawn from the pool passes through a filter and then to the heater. The gas burns in the heater's combustion chamber, generating heat that transfers to the water that's returned to the pool.