Exercise physiology loss of integrity to the blood brain barrier. Hyperthermia also can lower cerebral blood flow, and raise brain temperature. Researchers once attributed fatigue to a build-up of lactic acid in muscles. However, this is no longer believed. Rather, lactate may stop muscle fatigue by keeping muscles fully responding to nerve signals. The available oxygen and energy supply, and disturbances of muscle ion homeostasis are the main factor determining exercise performance, at least during brief very intense exercise. Each muscle contraction involves an action potential that activates voltage sensors, and so releases Ca ions from the muscle fibre’s sarcoplasmic reticulum. The
Neural control of limb stiffness virtually cocontracting antagonistic muscles about the robot's joints to modulate stiffness while a central pattern generator (CPG) controls the robot's locomotion. Other models of the neural modulation of stiffness include a feedforward model of stiffness adjustment. These models of neural control support the idea that humans use a feedforward mechanism of stiffness selection in anticipation of the required stiffness needed to accomplish a given task. Most models of the neural control of stiffness promote the idea that humans choose an optimal limb stiffness based on their environment or the task at hand. Studies postulate the humans do this in order