Muscle fatigue may be caused by a variety of factors. Understanding a few such factors may help determine your overall physical condition, whether you're working out too hard or pushing yourself too far when you exercise. Muscle fatigue may also be a symptom of illness. Signs are observable, while symptoms are those that you can feel or sense and relate to someone else. Know how your body feels so that you can tell if something doesn't seem right and discuss your concerns with your primary health care provider.
A common sign of muscle fatigue is weakness. Muscle weakness may make you feel like your legs are made out of spaghetti or that they can't support your weight.
Weakness may cause the leg muscles to twitch in what are known as myoclonic jerks, as is common if someone has been diagnosed with a condition called fibromyalgia. Muscle twitches are caused by nerve impulse signals sent from the brain that instruct the muscle to contract and relax quickly, like the flickering of a light bulb.
Reduced Activity Levels
You may feel a lack of energy or an inability to complete activities. This type of muscle weakness may be caused by inadequate blood flow to the extremities, especially for those experiencing cardiovascular issues such as high blood pressure or heart conditions, according to the "Merck Manual Home Health Handbook." For most people, such symptoms come on gradually, making it difficult to pinpoint the exact cause of the muscle weakness.
If you're in the middle of a weightlifting workout and suddenly feel you can't grip the barbell or dumbbell tightly enough, you may be experiencing muscle fatigue. Such weakness may also be experienced with signs of uncontrolled trembling. Such instances are known as exercise-induced muscle fatigue. A weak grip or trembling indicates that you are pushing or exceeding your limit -- your muscles are protecting themselves from injury.