Actually, work has alot more definitions than the one being described
in most of the tethered swimmer analysis. Yes, in a LINEAR mechanical
system work equals the integral of force acting through a distance, which
for a CONSTANT force is

Work = force x displacement.

In a ROTATIONAL mechanical system, the work is found by the integral of
torque acting through an angular displacement. Again for constant torque

Work = Torque x angular displacement.

There are other types of systems, so of course there are other types of
work, mainly electrical work and fluid work.

The tethered swimmer can be analyzed in a variety of ways depending on what
the real question is in regard to work. Net translational work done on the
mass? Rotational work produced by the arms? Biomechanical work produced by
the muscles? Total work done on the water? As others have said, the first
job in analyzing a problem of this sort is to identify the system of

The net translational work is easy to identify (zero displacement, zero
work), but all of the other calculations are extremely complex since the
torques, forces, local water pressure, etc are changing with time.

- Heather Abushanab
BU NeuroMuscular Research Center