By Jerry Lampson, HDL Keeper 25Jun02
There is a curious duality between brain and muscle. Exercise benefits the brain. Thinking about exercise benefits muscles. The rhythm of running is reflected in the electrical activity that plays in our brains. Most endurance athletes have intense dreams of their events that are hard to separate from reality. Brain and muscle decline with a similar rate as we age. Slowing the decline of one slows the decline of the other.
For HD the duality of brain and muscle is striking. In 1998 Arenas documented the muscle damage found in HD (ref). Most of HD literature address only brain defects for obvious reasons. Lose half your muscle cells and you will still do OK. Lose half your brain and you are in deep trouble.
The protein calpine is associated with muscle injury caused by intense exercise. After injury calcium enters muscle cells in massive amounts with devastating effects. Harsh biochemicals called oxygen free radicals punch holes in the cell membrane and calpains enter the cell to eat the cell's internal skeleton which causes the cell to collapse.
Recently calpine has been found in the brains of HD humans and not in controls.J Neurosci 2002 Jun 15;22(12):4842-9 Gafni J, et al.;Buck Institute for Age Research, Novato, California 94945, USA. This strongly suggests that calpine activity may accelerate HD. Reducing the activity of calpine will likely slow HD.
Previously it has been speculated, for good reason, that the casein found in cow's milk may accelerate HD.(ref). Soy milk was recommended to replace cow's milk. There is now good evidence that should convince all to choose soy protein over casein protein. Consider the following abstract ([added comments]).
We examined effects of dietary soy protein isolate on muscle calpain activity and myosin heavy chain (MHC) degradation in rats performing an acute running exercise.
In rats fed a 20% casein diet, the treadmill running exercise, fixed at 80 kg/m, transiently increased calpain activity in gastrocnemius muscles in parallel with the release of creatine kinase into plasma. The fixed running also caused an accumulation of immunoreactive degradation fragments of MHC in the muscle. [evidence of muscle damage]
Feeding a 20% soy protein isolate diet as opposed to the control casein diet to rats significantly suppressed the running-induced activation of mu- and m-calpains, fragmentation of MHC, and release of creatine kinase into plasma (P < 0.05).[evidence of supressed muscle damage]
Rats fed the soy protein isolate diet had significantly higher calpastatin [calpain blocking] activity in gastrocnemius muscle than did rats fed the casein diet (P < 0.05), indicating that this increase inhibits the exercise-induced autoactivation of calpain. Activities of proteasome, cathepsin B + L, and antioxidant enzymes and the levels of glutathione and thiobarbituric acid-reactive substances in the muscle did not differ between the diet groups at the end of the exercise.[evidence that calpain is the smoking gun]
Our results suggest that diets containing soy protein prevent exercise-induced protein degradation in skeletal muscle, possibly through inhibiting the calpain-mediated proteolysis [cell destruction].