The mistake: Your hands bump your knees, which throws off your cadence.
The fix: Take a tip from rowing crews to create a fluid motion: Think of the stroke as a dance, counting 1-2-3 and 3-2-1. On 1, push with your legs; on 2, “swing up” your body by leaning back; on 3, draw your arms to the bottom of your rib cage, spinning the flywheel. Then reverse it: 3, extend your arms; 2, swing your body forward from the hips; 1, bring your legs up after the handle passes your knees.
The mistake: A long, steady slog, which leads to inefficient exercise. You’re spending too much time rowing at a moderate intensity.
The fix: With medium resistance, do four to six 10-minute sets of high-intensity rowing with 2 to 3 minutes of rest in between. This will allow your heart rate to come down a bit so you can regroup with intense effort. Result: You’ll expend more calories and get out of the gym quicker.