There are some general properties shared by all forms of electromagnetic radiation: 1  It can travel through empty space. 2  The speed of light is constant in space. 3  A wavelength of light is defined similarly to that of water waves---distance between crests or between troughs.
The Parkinson Handbook Fatigue and Parkinsonâs Disease. Fatigue due to Depression-Depression is common in people with Parkinson's disease. It occurs in about 40% of the patients. Fatigue is a typical symptom of depression and is often reported as a lack of motivation or a loss of energy.
Muscle fatigue, or physical fatigue, is the decline in ability of a muscle to generate force. It can be a result of vigorous exercise but abnormal fatigue may be caused by barriers to or interference with the different stages of muscle contraction. There are two main causes of muscle fatigue. The limitations of a nerve âs ability to generate a sustained signal (neural fatigue) and the reduced ability of the muscle fiber to contract (metabolic fatigue).