Hand Weights
The products:Dumbbells that weigh 1 to 5 pounds and are designed to be
held while running, jogging, power walking, and doing step aerobics. Many of
these products claim to combine strength training with aerobic conditioning
in one workout, while causing you to burn extra calories.The reality: People who power walk with weights in their hands look quite
serious and impressive, but the truth is, these weights aren’t doing them any
good. Research on walkers shows that carrying hand weights burns only 10
to 15 percent more calories — a mere 20 to 30 calories over the course of an
hour, at least half of which come from exaggerating your arm swing, not from
the weights. (To put this in perspective: Speeding up from a 3-mph pace to a
4-mph pace burns an extra 54 calories.)Research on aerobic dancers suggests that you may actually burn fewer
calories holding hand weights than holding nothing at all. That’s because
weight-holding exercisers must keep both arm and leg movements tight and
controlled. In other words, you don’t move your body as much or as far
because if you flail the weights around, you get thrown off balance. As a
result, you burn fewer calories.Also, swinging hand weights vigorously can place undue stress on delicate
upper-body joints such as the shoulder, elbow, and wrist. Due to a concept
called torque, there are points in your arm swing when a weight exerts up to
ten times the usual force on your joints. In other words, a measly 3-pound
weight will place up to 30 pounds of force on those delicate joints. Plus, this
force is delivered in a jerky manner, which can do a lot of damage.Finally, realize that you’re not going to build strength with these weights. Any
dumbbell that’s light enough for you to carry around while walking is too
light to strengthen your muscles. As we explain in Chapter 13, to build strength
you need to lift weights that are heavy enough that you can perform no more
than about 15 repetitions of an exercise.378 Part VIII: The Part of Tens