Why do muscles shake during a strenous exercise?

Answer 1

Legs shakingYou say you are working out hard! Are you cooling down gradually or are you stopping your exercise abruptly? If you stop abruptly your circulation will be challenged and lack of oxygen to the muscles will cause them to spasm.

Get advice from a trainer about all aspects of excercise eg fluid intake, warming up and cooling down periods, working aerobicly and checking your heartbeat etc etc etc.

Exercise without proper understanding of your body's needs is PUNISHMENT!

More input from FAQ Farmers:

• I used to body build, I would work out prety hard and some times I would do some leg work first then go stand in front of the mirrors to do some shoulder raises and biceps work. some times my legs would shake badly and almost give out on me. This was just because I got a great work out.

• Your legs shake like that because you worked out hard. Your legs are tired and need to recover from a hard workout. Squats will do that to you with heavy weight. It means your doing a good job.

you might have a small tear in a quad or hamstring that would cause you to shake. Also , an abundance of caffeine or other dieuritic would explain the shaking.

Answer 2

muscles shake as they get tired,or are needing fluids etc the shaking is natures way of telling you to back off thats not entirely true. muscles can shake from the second you start an exercise. it's actually just your body telling you that they're not used to this movement. if you continue training those muscles over time the shaking will stop. expect to be sore the next day though :)

Answer 3

You have depleted the energy reserves of your muscles, but that's a good thing, since it trains the muscles to be more efficient, forces your body to build muscle tissue and helps your cardio system become more healthy. Keep it up, it's good for you.

Answer 4

Scientific American Magazine Explains Why Your Muscles Tremble After Exercise

Loren G. Martin, professor of physiology at Oklahoma State University in Tulsa, responds: "Let's start by examining what happens when you exercise. In skeletal muscle, the cells never contract individually. Rather they contract as groups of muscle cells that are collectively connected to a motor nerve originating in the spinal cord; the combination of the motor nerve cell (neuron) and the muscle cells it innervates is known as the motor unit. "The size of the motor units determines the precision of movement that a particular muscle can produce. For example, in the muscles of the larynx, or voice box, each motor nerve usually connects to only two or three individual muscle cells, allowing very fine gradations of strength. On the other hand, large muscles that serve gross movement--such as the gastrocnemius muscle in the lower leg--have motor units made up of motor nerves that each control 2,000 or more muscle cells. "These motor units are not all excited simultaneously when a muscle is electrically excited and made to contract. In fact, the units are excited in a most asynchronous fashion by the trains of electrical impulses that come down the motor nerves from the spinal cord. As a result, while some of the motor units are contracting and shortening within the muscle belly, others will be relaxing and lengthening. The tremendous amount of overlap between motor units gives the appearance that the muscle is contracting smoothly overall. "Strenuous exercise causes some of the motor units to drop out of service because of fatigue; it is this process that is ultimately responsible for the trembling you observe. Most of the fatigue probably occurs within the spinal cord at the level of the motor nerve cell and its neural connections, although some fatigue probably occurs also at the connections between this motor nerve and its muscle cells (the myoneural junction). Both these areas require the synthesis and release of particular chemicals to carry the electrical impulse across to either another nerve cell or a muscle cell. Researchers generally believe that the chemical cannot be manufactured and released fast enough to keep up with the level of activity, so it becomes depleted in this area of transmission. The depletion of these chemicals is a big part of what fatigue means in a biochemical sense. "As more and more motor units become temporarily nonfunctional, the muscle contraction becomes dependent on fewer and fewer motor units. The dropout of the fatigued motor units causes the remaining individual contractions and relaxations to become on average more synchronous and less smoothly organized; the original overall appearance of a smooth contraction is replaced with a jerky, trembling movement now that many of the overlapping motor units have ceased to function. After adequate rest, the fatigued motor units return to normal, and the muscle again appears to produce a smooth contractile motion. http://www.sciam.com/article.cfm?id=why-do-muscles-tremble-af&topicID=3

Answer 5

Its not just your legs, but most exercises involve you leg muscles, jumping, running, jogging, skipping, squats, and even press ups to a degree all involve leg exercising and as they are the main functioning muscle as y9our walking most of the day or standing they will suffer from fatigue. As there the most worked muscle they will othen be the 1st muscle to give out.

Any muscle can give out when exercising it past the point in which it can take, like lifting weights your arm or chest muscles will eventually give out the longer you do the exercise and how hard you push.

It maybe down to life style as well, if your sitting all day your muscles wont be used to prolonged activity so your legs would be more susceptible to burn out quicker than those who are constantly on their feet.

Answer 6

well it's like this, if you've been sitting down for some many minutes, and you're stiff, when you stretch you start shaking your leg because you' rereleasing the stiffness from your leg