Cytological basis of decrease in muscle strength during starvation

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Abstract
The effect of partial starvation on the mouse biceps brachii was to cause muscle fibers existing in a "large phase" of diameter 42 µ to revert back, in an "all-or-nothing" manner, to a "small phase" of 23 µ diameter. During a subsequent recovery period the reverse change took place at the same rate as during starvation. The time for one phase to be converted into the other phase was in the region of 1–2 days. When a large-phase fiber reverts back to the small phase there is a disproportionately large decrease in its myofibril content due to a decrease both in the number and in the size of its myofibrils. This results in a difference in the packing of the myofibrils in these two phases. Measurements of muscle strength were made and these could be directly related to the changes in the myofibril content of the fibers. The tension that a single small-phase fiber and a single large-phase fiber could develop was calculated to be 2.8 mg and 17 mg, respectively.