The biceps is responsible for flexing your arm at the elbow.
Muscles are most well known for their producing movement, such as the swinging of the legs and lifting of the arms. But they're also working isometrically throughout your daily routine, which means they're contracting to hold you in a particular position. When your biceps are working isometrically, they're holding your elbows in a flexed position against resistance, such as when you're holding a heavy bag of groceries.
An isometric exercise requires you to hold each rep for a set period of time, instead of traditional biceps exercises that involve you continuously bending and extending your elbows. When you're doing an isometric workout, you'll instead force your biceps to hold your elbows in a static, flexed position. Incorporate the workouts into your schedule no more than three days per week so that you can put a day of rest in between each one. Complete each isometric biceps exercise for two or three reps each; hold each rep for 10 to 15 seconds.
Hold the Curl
The isometrics biceps curl can be done with either a pair of dumbbells or a single barbell. Stand and hold the weight with your arms hanging by your sides and your palms facing forward. Bend your elbows until they're at 90 degrees and your forearms are parallel to the floor. Hold this position for 10 to 15 seconds. Keep your wrist in a neutral position throughout each rep. Select a weight that makes holding the position for 10 to 15 seconds challenging.
Hang From the Bar
Isometric chin-ups require the use of an overhead bar or pullup machine. Reach up and grip the bar with your hands at shoulder width and your palms facing you. Pull your body up toward the bar until your elbows are bent to 90 degrees; hold that position for 10 to 15 seconds. You're lifting your body weight during the isometric chin-up, which means the load you have to hold has the potential of being too heavy or too light. You can place your feet on a stool or bench to decrease the load on your biceps. To add weight to the exercise, hold a dumbbell or weight plate between your feet.
No Weights Needed
You can also isometrically work your biceps without any weights. Stand or sit and hold one of your elbows bent to 90 degrees. The elbow should rest against the side of your torso. Contract your biceps as you hold this position. With your opposite hand, gently press down on your forearm to add a load that your biceps must work against. You can increase or decrease the load by adjusting how hard you're pressing your forearm. Don't forget to switch sides and work the other arm once you're finished.