20 minutes is around about 1 mars bar
Depends on the intensity.
Depending on what are you doing on a rowing practice, but certanly A LOT!
Are you referring to on the water rowing, or rowing indoors on an ergometer? Both burn calories at a very rapid rate. On a concept 2 erg machine, you can select a screen that displays the number of calories per hour. On the water, it is a bit harder to gauge, but if you plan on rowing competitively, you can easily burn over 1000 calories in a 2-3 hour session. From my experience as a varsity collegiate rower, throughout our rigorous two-a-day practice sessions, it is necessary to consume nearly 5000 calories a day, and weight can still be lost. Depending on the level you seek to row at, you can easily burn a huge amount of calories.
About 90 calories.
It depends on how long you use each machine. Rowing machines are primarily used for strength development. Because of this, they do not burn many calories at once. However, they serve a different purpose of building calorie-burning muscle.
you burn nothing cause your fat
About 450 calories
50
2
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You don't burn much, but certainly about a good 20 to 50 calories.
10 calories an hour, sugar free gum.