Weakened soleus causes older women to fall
Elderly women who want to prevent a fall would do well to include seated calf presses in their strength training routine. Nicole Chimera, a sports scientist at Daemen College in the US, writes about this in the Journal of Strength and Conditioning Research. Chimera discovered that women fall more often than men because their calf muscle, the soleus, is weak.
Muscle decline & falling
The reason why both men and women are more likely to fall as they age is obvious. Muscle mass declines and, with it, strength. But this doesn't explain why women over the age of 60 are seventy percent more likely to fall than men of the same age.
In the 1980s British sports scientists discovered why. [Clin Sci (Lond). 1988 Jan;74(1):85-9.] Women in their sixties have less strength in their calves than men - even if you take into account the difference in muscle mass between men and women.
The soleus is the deeper calf muscle; above it you find the gastrocnemius. The gastrocnemius is attached to the thighbone, the soleus isn't. If you train your calves with bent knees the gastrocnemius can't contract, so you can't train it properly. If you train the calves doing seated exercises it's the soleus that you use mainly.
Chimera realised that researchers hadn't looked at the soleus and gastrocnemius separately. She got together a group of 12 women and 13 men aged between 40 and 60, and started by measuring the amount of strength they could develop using their calf muscles.
The results are shown below. They show the strength [in Newton] per kg bodyweight that the men [dark] and women [white] were capable of developing with straight and bent knees. The women did indeed have less strength in their calves than the men.
Chimera then calculated the percentage of the calf strength that originated in the gastrocnemius and the percentage that originated in the soleus. She discovered that women have demonstrably weaker gastrocnemius muscles than men. The p was 0.05.
After correcting for the difference in muscle mass between men and women, the difference in strength disappeared. The p was 0.30, and the difference in strength was no longer significant. So, she reasoned, women have less strong calf muscles than men because their soleus, not their gastrocnemius, is weaker.
"The middle age women in this study have significantly weaker soleus muscles than similar age men even when normalized for differences in body size", Chimera concludes. "Thus, it may be important to perform strength training to specifically target the soleus muscle in women during middle age years."
J Strength Cond Res. 2013 Sep;27(9):2596-602.
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Anti-Aging & Muscles