If you've just started working out regularly, it may be hard to avoid muscle fatigue initially. It will typically take some time to build up your endurance levels when exercising so that fatigued muscles are not a problem for you. You might be able to limit how often you experience muscle fatigue by not pushing yourself further than you are capable of handling when exercising. If you begin to feel your muscles giving out, stop and take a break. It's also a good idea to drink lots of water or sports beverages containing electrolytes, which are helpful for preventing both muscle cramping and muscle fatigue.
You can work to build up your endurance levels by participating in aerobics and strength training regularly. It may be a good idea to start off slowly with 10- to 15-minute workouts and then work your way up to 30-minute workouts over the course of a few weeks. Building up your muscle strength is possible, but you may be much less likely to experience muscle fatigue if you go about it gradually rather than trying to do too much at once. Over time, you may reach a point where your muscles are strong enough that they rarely become fatigued, and you will also likely start to gain a better understanding of your limits when exercising so that you'll know when to stop and take breaks before fatigue occurs.
Hydration is also typically considered very important for preventing muscle fatigue. As you sweat, your body normally loses lots of precious fluid, and this loss of fluid might make you give out much faster if you aren't replacing it while you exercise. Water is a good choice for replacing lost fluids, but sports beverages containing electrolytes may also be very beneficial because when you sweat you lose both sodium and potassium as well as water. Sodium and potassium are both important for keeping your muscles working properly. Drinking beverages containing electrolytes will replace these components in addition to replacing the water your body loses through sweat.
A good diet is also considered important for avoiding muscle fatigue. Meals containing a mix of proteins, carbohydrates, and fats eaten approximately one hour after your workouts will help your body refuel itself, which might in turn prevent the likelihood that you will experience muscle fatigue during your upcoming workouts. It's also not typically a good idea to begin a workout on an empty stomach. Eating healthy, well-balanced meals at least a few hours before you start working out might help prevent you from becoming tired and experiencing muscle fatigue as you exercise.