Alex Hutchinson draws on the latest research to answer your fitness and workout
questions in this biweekly column on the science of sport.
The question
Do I get the same workout from the elliptical machine that I get from running?
The answer
More than 23 million Americans used elliptical trainers in 2007, according to
the Sporting Goods Manufacturers Association - triple the number that used them
in 2000. Canadians have also eagerly adopted the low-impact, pseudo-jogging
machine.
Despite this popularity, there's still some haziness about the benefits of
elliptical use - even among researchers. The biomechanics of the low-impact
elliptical motion are still poorly understood, though studies now suggest it
could help ward off several common running injuries. And there's no consensus
about how hard your body has to work compared to other exercises.
A 2005 University of Scranton, Pennsylvania, study found that at a self-chosen
"hard" level of exercise, subjects consumed more oxygen and had higher heart
rates on the treadmill than the elliptical. In contrast, a University of Idaho
study in the same year found that the elliptical felt easier than either the
treadmill or recumbent bike, despite producing the same oxygen consumption and
heart rate.
Subsequent studies have added little clarity, which suggests that any
differences are too small to matter. An Irish study published in the Journal of
Sports Medicine and Physical Fitness appears to be the only one to tackle what
really matters to most people: fitness and weight loss. A group of 24 women
performed a 12-week fitness program using either an elliptical, treadmill or
stair-climbing machine. Cardiovascular fitness increased and body fat percentage
decreased to the same degree in all three groups.
There are other differences, though. A forthcoming study by Western Washington
University exercise scientist Kathleen Knutzen used elliptical machines with
force plates on the pedals to determine that, even at a fast stride, the forces
on the lower legs were comparable to walking, and two or three times less than
running.
"That's a real benefit if you're prone to repetitive stress injuries," Dr.
Knutzen said.
More generally, the constrained elliptical stride calls on muscles in a
different way than running freely would, much like the differences between
lifting free weights and using a weight machine. That means that the elliptical
will never be a perfect substitute for running - but it can be ideal for those
with injuries such as patellofemoral pain syndrome, often called "runner's
knee." The injury is sometimes caused by an imbalance between two parts of the
quadriceps muscle, which pulls the kneecap off-centre during each stride
The elliptical also allows you to pump the arm handles to get your upper body
involved in the workout. Studies by Constance Mier and her colleagues at Barry
University in Florida found that using the arm handles made little difference to
oxygen consumption, heart rate or perceived effort. However, the two actions are
sufficiently different that alternating between them might allow you to last
longer - and thus get a better workout - when using the elliptical, Dr. Mier
suggested.
Ultimately, the elliptical is a perfectly good way to get fit. But unless your
goal is to master the art of moving your feet in little ellipses, it makes sense
to add in other, more functional activities such as walking, running or biking.
"Mix it up," Dr. Knutzen advises. "Don't do the same thing every day."
Alex Hutchinson is a former member of Canada's long-distance running team, and
has a PhD in physics.
