Saturday, August 22, 2015

How Long To Burn Off A Cookie? Exercise for Strong Bones

Have you ever said:  “I exercised today so I can eat that extra cookie”?  Let's play around with some numbers here....

What about if you ate a cookie a day for a year, how much weight might you gain?  (This is straight from a test I gave while teaching exercise nutrition – are you smarter than a college sophomore?)

Making a few assumptions:  Assume one cookie = 100 calories.  Assume also that it takes 3500 calories extra to gain one pound weight.  Doing the math:

100cal x 7 days = 700 calories a week extra.  700 calories x 52 weeks = 36,400 calories extra in a year.  Divide by 3500 calories per pound, and you get 10.4 pounds a year from that extra cookie a day.

Now, what if you decide you’ll “work it off” by exercising.  How much walking, running, swimming, etc. would you need to do?  Maybe more than you think…

From (not related to & based on a 150 pound person, 100 calories is equal to:

23 min biking
9 min running – 6 mph pace
15 min swimming – moderate intensity
20 min walking – 3 mph pace
20 min yoga
35 min bowling
21 min tennis (doubles)
15-20 min yardwork
26 min house cleaning
38 min shopping
26 min walking the dog

Next, how many of us stop at a 100 calorie cookie?  While “calories in, calories out” does make sense for weight control, remember that most treats are much more caloric – a large donut can be over 350 calories!  What if your indulgence is an extra piece of pizza at over 300 calories?  Or a fast food burger at 325 to more than 900 calories?  Add fries?  That’s an extra 450 calories for a large order.

That donut could take 35 min of swimming and 54 minutes of walking or an hour of yoga.   While its good to allow ourselves a treat every now and then, a better weight loss strategy, is to exercise regularly, and to keep counting.
 For a 150 lb man who can run 10 min/mile, here's how long it would take to "work off" some popular indulgences*:

Chocolate cake – 675 calories requires 33 minutes of running
MacDonald’s Big Mac o- 560 calories – 50 minutes of running
Burger King Double Whopper – 900 calories or 1 hour 20 minutes
Bluebery Muffin, extra large – 465 calories – 41 minutes
Godiva Chocolate Amaretto Truffle = 110 calories – 10 minutes
Ice cream 10% fat, ½ cup – 201 calories – 18 minutes

You get the idea…most of us may not be able to run 10 minutes/mile.  If you’re a walker at 3.5mph, all of the above indulgences will take much longer to “work off”.  Might be food for thought before indulging, actually. See the references for a few more examples.**

And if you’d like to apply this reasoning to your own activities and intake, check out this Calorie Burn Calculator.

Bottom line:  we’ve made a lot of assumptions here to make the point that its not realistic to “burn off” that dietary indulgence by simply doing a “little more” exercise.

Boost Those Bones – Exercise and Strong Bones
The standard advice for older adults facing possible bone loss – osteopenia or osteoporosis - is to do weight bearing exercise.  This is anything you do to move your muscles against the force of gravity.  Ultimately it’s the muscles pulling on the bone that stimulates bone building.  Its not just things we do our feet, like walking or running, its any load bearing work – hitting tennis balls, moving your potted plants around, or toting groceries from the car, as well as traditional “strength exercises” done with dumbbells, machines, kettle bells, medicine balls, and so forth.

How much your bones benefit from exercise depends on many factors – heredity, sex, diet, and age.  Young bones are much more responsive to the stress exercise places on the bones.

The type of exercise is also important – the more you can load the bones, the greater effect.  High impact is best for bones…however, that doesn’t take into account the effect of high impact on older joints!  The intensity obviously has to take into account your tolerance for high impact exercise.

What’s Best for Bones?  From the 2004 Surgeon General’s Report, here’s a ranking of exercises and their bone strengthening benefits:

Weight bearing, high impact or resistance activities (best for bones):  running, jumping rope, stair climbing, basketball, volleyball, tennis, skiing, soccer, hiking, gymnastics, weight training, hiking, dancing

Weight bearing, low impact:  brisk walking, low impact aerobics, most cardiovascular machines – stair climbers, rowers, elliptical trainers

Nonimpact/weight bearing:  swimming, yoga, pilates, stretching, indoor cycling.  Obviously intensity matters, and can boost a low impact activity up in benefits.

The research shows that physical activity can improve bone mass, but that it is site specific – arm exercises won’t increase the bone density of the hips, for example.

The effect of physical activity does not persist if you stop moving!  You will need to maintain optimum intakes of calcium and physical activity levels.  Periods of physical inactivity causes bone loss.  Even if bed rest is necessary, brief weight bearing movements can reduce this bone loss.

Lastly, the effect of physical activity is greater in those who are less active than those who are already active.

Here’s a simple program of activity for adults concerned about bone heatlh from the Office of the Surgeon General:

Thirty minutes of activity a day.
10 minutes of physical activity including 50 3” jumps per day.
Progressive weight training for all major muscle groups.
Jogging or stair climbing for those who cannot perform higher impact activity.
Active recreation activities such as tennis, hiking or basketball.

Studies have shown that simply hopping on one foot most days of the week for six months, can increase bone mineral density on that leg.  Multidirectional jumping as seen in tennis, soccer and some kinds of dance, is even better, because it stresses the bones from different angles.

Split workouts of 10-15 minutes with three hours between bouts, have also been shown to be more effective than one long session.

Those who are unable to tolerate high impact exercise or are frail should concentrate on maintaining muscle strength & improving balance to reduce the risk of falling.  Do weight bearing exercise at least 3 times a week.  Even a small gain in bone strength may prevent a fracture,

* Ivan Nikolov The Critical Bench
Berkeley Wellness Letter:  Oct 1, 2012.  New Tricks for Old Bones.
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