Aerobic workout versus machines

Published 5:40 pm Friday, April 14, 2006

By Staff
Q: Can aerobic fitness be improved if a high heart rate is maintained during strength training?
A:  Using a high level of effort - that is, training to or approaching the point of muscular fatigue or &#8220failure”-and taking a minimal amount of rest/recovery between exercises/sets produces a high heart rate.  
Training in this fashion places a large demand on the musculoskeletal, respiratory and circulatory systems.  
But it doesn't necessarily follow that this stimulus produces a significant improvement in aerobic fitness.  
Here's why:  
During physical activity, heart rate and oxygen intake are good indicators of effort.  
However, the response produced by strength training is different than that produced by aerobic training.  
For any given heart rate, strength training produces a lower oxygen intake compared to aerobic training.  
Some research has shown that the difference is about 70 percent.  
So, attaining a heart rate of 140 (beats per minute) during aerobic training might correspond to an oxygen intake of 20 ml/kg/min., but that same heart rate during strength training might correspond to an oxygen intake of 14/ml/kg/min.
Or look at is this way:  For any given oxygen intake, strength training requires a higher heart rate compared to aerobic training.
Q:  Can I get the same workout from an elliptical machine as I can from a treadmill?
A: The term &#8220elliptical” refers to the pattern that the pedals make when the machine is viewed from the side.  
The first elliptical machine of any meaningful value was unveiled in 1995.  
Since then, it has become an increasingly popular piece of equipment for aerobic training.  But how does it stack up against the ever-popular treadmill?  
Studies have shown that the physiological responses of using an elliptical and a treadmill are similar - such as in maximum heart rate, maximum oxygen intake and the respiratory exchange ratio.  
So why does it feel so much easier to use an elliptical?  
The reason is probably because it's a no impact activity that doesn't involve the pounding that's associated with a treadmill.  
Many ellipticals have an upper-body component that allows users to address all major muscle groups, not just those in the hips and legs.  
Using this type of elliptical can produce an even greater expenditure of calories.
Janet Peterman is a personal trainer at the Brewton YMCA. She can be reached at 867-9622 (YMCA).

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