'One needs a jock and is a racket, err, is for jocks and needs a racket!'
Not giving him an adequate or professional answer, I scoured the internet.
The thing was that every place I looked, I found a different answer!
That was because tennis and treadmill ARE different - not like comparing apples and oranges, but oranges and tangerines.
What makes this question tough to answer is that there is a lot of variability between the two activities - not even considering the differences from person to person that are present.
Differences & Variability -
Tennis is primarily BOTH aerobic and anaerobic (short bursts), where treadmill is primarily aerobic if done for an hour.
Treadmill is 100% 'activity', but tennis is not. What % of the total hour is for 'real play'?
What intensity is the tennis (recreational/competition) and the treadmill (speed/incline)?
Calories -
Each mile on a treadmill will burn around 100 calories, depending on incline and individual body differences.
Recreational Tennis Energy Expenditure by body weight:
Yesterday one of my clients asked me,