Gender Differences in Fatigue Explained by the Use of the
Body's Aerobic Pathways
Women demonstrate greater metabolic efficiency, leading to
reduced production of by-products that cause muscle fatigue
New Orleans, LA -- Differences in fatigue between men and women have
been found in a number of previous research studies. The collective results
are mixed, but a significant number of findings indicate that women fatigue
less than men.
One proposed mechanism suggested to explain this difference in
fatigability is that women are better able to utilize oxidative pathways of
metabolism to provide the energy for muscle contraction. Efficient
utilization of these aerobic pathways results in the production of lesser
quantities of metabolic by-products such as inorganic phosphate, which is
thought to contribute to muscle fatigue.
New research to validate this hypothesis is being presented before an
annual gathering of the nation's leading physiologists. The author of
"Effects Of Ischemia on Gender-Dependent Differences in Human Skeletal
Muscle Fatigue," is David Russ, Ph.D. from the University of Massachusetts.
He will present his findings in detail at the American Physiological
Society’s (APS) annual meeting, part of the "Experimental Biology 2002”
conference. More than 12,000 attendees will attend the conference
being held at the Ernest N. Morial Convention Center, New Orleans, LA from
April 20-24, 2002.
Methodology
This research investigation compared the fatigue produced by an identical
exercise protocol in men and women under two different conditions: a control
condition and an ischemic condition, where blood flow (and thus oxygen) to
the muscle is cut off by mechanical compression. If gender differences in
fatigue exist and are due to an "oxidative advantage" for women, then the
results would demonstrate that women exhibit less fatigue under control
conditions, but that women and men would fatigue equally under ischemic
conditions. The measures of fatigue in this study are voluntary force
production, electrically stimulated force production (which eliminates
motivation as a factor), and electromyography (which examines the level of
muscle activation).
Results
The results support the hypotheses that women fatigue less than men, but
when deprived of oxygen, they fatigue to the same extent.
Conclusions
This effort examined only one muscle, the tibialis anterior (upper
two-thirds of lateral surface of tibia, interosseous membrane, and
intermuscular septum). The researcher cautions that results might well vary
for different muscles. Further, the findings do not explain the mechanism of
the "oxidative advantage" in women. One reason could be due to more
efficient and increased oxygen delivery or to a greater oxidative capacity
to utilize the oxygen that is delivered to the muscle, or a combination of
the two. Finally, the difference in fatigue is likely task-dependent and
might change if the type of exercise changed.
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The American Physiological Society (APS) is one of the
world’s most prestigious organizations for physiological scientists. These
researchers specialize in understanding the processes and functions
underlying human health and disease. Founded in 1887 the Bethesda, MD-based
Society has more than 10,000 members and publishes 3,800 articles in its 14
peer-reviewed journals each year.
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Editor’s Note: For further information or to schedule an interview, please contact Donna Krupa at 703.967.2751 (cell),
703.527.7357 (office) or at
djkrupa1@aol.com.
