This is why your muscles shake after you work out

If you've ever left the gym feeling a little shaky after a hard cardio or strength session, don't panic: That feeling is normal. In some cases, though, it is a warning sign from your body letting you know that you've pushed yourself too hard, or improperly fueled the work you were doing.

Pushed hard through one last set of bicep curls? If you're shaking after, that's because your body can't keep up with the level of activity you've asked of it, but if you wait a few minutes, that trembling should subside (via Scientific American). If this is happening after every workout, listen to your body and dial back your intensity, weights, or total number of repetitions (via LiveStrong). 

There are diminishing returns when you start to push your body past its current capabilities. "Twitching is not associated with improvement in terms of strength," Doctor Joseph P. Garry told the Huffington Post. Rather, it's a sign that your body is ready for a rest. 

If you've been doing a cardio session or a more high-intensity boot camp workout, your muscles may be tired, but the real reason for the shakiness could be nutrition-related. Low blood sugar, dehydration, and a bit too much espresso sipped before starting your workout could be to blame (via Healthline).

The nutrition-based reasons you're shaky

Low blood sugar can happen as your body depletes its glycogen stores during exercise and switches to using glucose for energy instead. In addition to shakiness, other signs that you're suffering from low blood sugar post-workout including feeling ravenous, sweating, fatigue, dizziness, and confusion. You're also more likely to suffer from ups and downs in blood sugar due to exercise if you're diabetic. The solution is simple: Make sure you're fueling workouts appropriately, and have a carbohydrate-rich post-workout snack on-hand (via LiveStrong). 

Shakiness caused by a bit too much caffeine is easy to spot: If you're jittery, if your heart is racing, or if you have the intense urge to sprint for the bathroom, and you know you drank a lot of coffee or other caffeinated beverages before starting your workout, caffeine is likely the culprit. (Check for sneaky sources of caffeine in sports drinks and gels if you feel these symptoms but haven't been drinking any coffee.)

Lastly, dehydration can cause your muscles to feel shaky, though more likely, you'll feel cramps and twitching rather than shaking. Other symptoms include dark or reduced urine, dizziness, and full-body weakness. Rehydrate by sipping water or a sports drink with electrolytes in it to restore balance.