The front thigh muscles are called the quadriceps, and the back thigh muscles are called the hamstrings. The buttock muscles also are called the gluteals.
For this exercise, you need two dumbbells of equal weight, 5 to 10 pounds each. Use a light weight until you become familiar with the exercise.
Stand straight with your feet hip-width apart, knees slightly bent. Hold a dumbbell in each hand by your sides, palms facing your thighs. Take a large step forward with your left foot. Bend both knees at once into the lunge position. Bend the left knee until it is straight up from the left ankle. Bend the right knee until it is several inches above the floor. The right heel naturally lifts off the floor. Keep your torso erect. Hold the down position, and then push off the ball of your left foot to straighten the legs and return to the start position.
Repeat with the right leg forward. A front lunge with both legs counts as one repetition. Do 8 to 10 repetitions.
Remember to move slowly, under control. Maintain your balance in each position before moving into the next. Count one as you step forward, two as you drop the knee and hold in the down position, three as you push off the ball of the foot and return to the start position, and four as you stand erect and ready to start again.
To avoid knee injury, don't allow your knees to extend in front of your toes. Keep your body weight directly over your heels.