Lately I've been seeing something rare in my apartment community's fitness center: a repeat visitor (I may have mentioned before that it's not well frequented). This individual, a petite woman in her twenties, has been coming in to work out while I'm there a couple of times a week the last few weeks, so I've had the opportunity to observe her routine. She generally only does cardio, and while this often includes running on the treadmill, one of the more challenging cardio options available, I've noticed she does something that's technically a cheat, something that makes the work easier, something that I've seen a lot of people do on all kinds of cardio equipment...
(Are you paying attention? Clearly I'm about to drop a big bomb here.)
She hangs onto the machine.
Okay, perhaps I should elaborate. She supports a portion of her body weight on her arms by hanging onto the handrails, so the upper half of her body is barely moving while her legs are moving furiously by comparison. It looks like she's driving the Flintmobile. Now, it's not uncommon to see someone doing this on the stairclimber, the stepmill, or the elliptical, but while running, it's a bit ridiculous, not to mention dangerous.
I'm not sharing this anecdote to make fun of said person, or anyone else for that matter, but to point out what's fundamentally wrong with supporting your body weight on the machine's rails. Simply put, the more body weight you're moving during any activity, the more calories you're burning, all other variables aside. By letting go and pumping your arms---therefore moving your whole body---you'll get a better workout in the same amount of time. You'll get your heart rate up, and by keeping your chest lifted instead of leaning forward, you'll be able to get oxygen more effectively. This is also much better for your core muscles, which will work harder to hold you upright and help you maintain your balance.
Remember that it's challenging yourself that yields results. If it's not work, it's probably not working. I'm just sayin'.