The USDA created the food pyramid to encourage a healthy diet, but the USDA also has a mission to encourage agricultural products grown in the US. There can be a LOT of conflict between those two goals. So the food pyramid (ahem, I mean MyPlate) is not simply an objective summary of the available evidence.
The stretch reflex (myotatic reflex) is a muscle contraction in response to stretching within the muscle. It is a monosynaptic reflex which provides automatic regulation of skeletal muscle length. When a muscle lengthens, the muscle spindle is stretched and its nerve activity increases.
When a muscle is stretched, the spindles in that muscle are also stretched. Stretch of the nuclear bag and chain fibers in the spindles stimulates the primary and secondary endings of the Ia and II afferent fibers, causing them to send impulses into the cord.his stretch-resulting-in-relieved-stretch is known as the myotatic or stretch reflex. Once the muscle contracts and the stretch is relieved, the firing rate of the spindle afferents returns to the resting level.