Yes when you want to tone your stomach the Rowing Machine is the best exercise machine to tone your stomach.
A Rowing Machine will give you a full body fat burning workout by engaging your core which tones your stomach muscles and your other muscles as well.
You get a good cardio workout and tone your stomach and overall body as well so it's a win win.
The Rowing Machine will build stronger abdominal muscles and burn fat which tones your stomach and it can help you lose weight if you want to or need to lose weight.