A rowing machine, is a machine used to simulate the action of watercraft rowing for the purpose of exercise or training for rowing. Rowing machine with a digital display calculate the user’s power by measuring the speed of the flywheel during the stroke and then recording the rate at which it decelerates during the recovery. Using this and the known moment of inertia of the flywheel, the computer is able to calculate speed, power, distance and energy usage. Some rowing machine can be connected to a personal computer using software, and data on individual exercise sessions can be collected and analyzed. In addition, some software packages allow users to connect multiple rowing machines either directly or over the internet for virtual races and workouts.