Shaking or trembling after a workout might be cause for alarm, but in many cases, the problem is due to something simple, such as fatigue or malnourishment. Taking measures before and after working out can help prevent the shaking in many cases, and it is often easily treatable when it occurs. If you shake consistently after your workout or shake when you are not working out, consult a doctor.
If you work out when you are tired and sore, or if you push yourself too hard during your workout, it can easily lead to muscle fatigue followed by shaking. Another common cause is holding your muscles in one position for too long, which can also lead to muscle fatigue. Your muscles move efficiently because the different motor units — a group of muscles and a motor nerve in the spine — work together to create an even, smooth contraction. If you are fatigued, some of the motor units drop out and quit working, leading to shaking and trembling, Dr. Loren G. Martin, a professor of physiology at Oklahoma State University, explains. Once you rest your muscles sufficiently, the shaking should stop.
Low Blood Sugar
Working out without proper nourishment means your body doesn't have enough energy to function — and that includes your muscles. If you skipped a meal or didn't eat enough to fuel your muscles, your levels of glucose, or blood sugar, will be too low — a condition medically referred to as hypoglycemia. In addition to trembling or shaking muscles, you might also have symptoms such as irritability, nervousness, dizziness, confusion and weakness. Eating a small snack that contains carbohydrates or sugar, such as peanut butter and crackers or a glass of orange juice, can help ease the shaking from hypoglycemia.
Muscle fatigue and hypoglycemia are probably the most common causes of post-workout shaking, but other factors can either contribute to or cause the problem. Consuming excessive amounts of alcohol, alcohol withdrawal, caffeine or certain medications can lead to trembling and shaking, as can stress and anxiety. Rarely, an underlying medical disorder that affects the nerves, such as multiple sclerosis or Parkinson's disease, is to blame.
To prevent muscle fatigue, work out within your limits and avoid pushing yourself too hard. Avoid working your muscles to the point of fatigue and soreness. Make gradual changes to your workout, avoiding sudden jumps in intensity or duration. Warm up before working out and stretch your muscles after your warmup and after working out. Eat a full meal at least two to four hours before working out to avoid low blood sugar. If you missed a meal, try to consume a small snack at least 30 minutes before your exercise session begins. Avoid consuming too much coffee or other caffeinated products and ensure you get enough rest. If taking preventive measures doesn't stop the problem from occurring, consult your doctor to rule out an underlying medical disorder. Talk to your doctor about any medications you are taking to ensure shaking is not a side effect.