Abstract: An instructional, training, and assessment apparatus is provided for use in the activity of swimming. The apparatus includes a cable having a proximal end and a distal end, and a harness for coupling the distal end of the cable to a swimmer. A mechanism is coupled to the proximal end of the cable for winding and unwinding the cable to apply positive and negative forces to the swimmer as the swimmer swims laps in a pool. The apparatus of the present invention can also be used with a mechanism that applies only positive forces to the swimmer. A sensor is provided for generating an output signal responsive to a parameter measured by the sensor. The apparatus also includes a programmable controller responsive to the output signal from the sensor and to preprogrammed control parameters for controlling the forces applied by the winding and unwinding mechanism.