Typically, back day is a slow and long workout with heavy weights. However, if you're sticking to low reps, high reps, you may be selling yourself short.
High-intensity interval workouts, which use lighter weights and higher reps, in quick succession, will help you burn fat while putting your body into prime muscle building mode, letting you sculpt muscle at the same time.
The following HIIT back workout will hit your back from all directions while keeping your heart rate up and your recovery periods short so you are moving as fast as you can, and never stop moving. Because of the intensity of the workout, you'll be using only your body weight or light weights to ensure you keep proper form and avoid burning out before the workout is over. If light weights have you skeptical, don't worry, by round two, you'll be begging for mercy.
HIIT Back Workout
Do 10 reps of the following exercises. Repeat for 3 sets, resting as little as possible between each exercise.
Hold a barbell with an underhand grip, hands just wider than your hips, the weight resting along the front of your thighs. Draw your shoulder blades back and down, lifting your chest and keeping your back flat. Hinge forward at the waist letting the barbell hang, gravity pulling your arms perpendicular to the ground. To begin: Flex through the elbows to pull the barbell to your chest. Keep the elbows squeezed in by your sides, like there is an imaginary string attached from your elbows to the ceiling. Don't pull up on the weight with your biceps, the movement should be initiated with your back. Pause and squeeze, then slowly release back to starting position.
Stand feet shoulder width apart with a medium weight dumbbell in each hand. To begin: squat down, placing the dumbbells on the ground in front of you, perpendicular to each other. Pop your feet back into plank position. Lower into a pushup and come back to plank. Keeping your hips square, row with the right arm, row with the left, hop your feet back into a squat and clear the dumbbells to your shoulders. Extend through the legs and arms to perform a shoulder press and repeat.
Stand facing the anchor with a TRX strap in each hand. Extend your arms and lean backward, keeping your body a straight line from your head to your heels. To begin: Keeping your arms straight, open them up to your sides to perform a fly. Your body should rise in between your arms to form a T. Make sure you bring your arms wide, horizontally, and move in a slow and controlled manner in both directions. Don't push your neck forward, keep it relaxed. If it's too difficult, just take a step back: the closer your are to horizontal the harder the exercise will be.
Burpee to Pullup
Stand underneath a pull up bar. Bend through the waist and knees to place your hands on the floor. Pop your feet back into plank position and drop your chest to the ground. Push up into plank position and bring your feet back in to meet your hands. Explode through your legs to jump and grab the pull up bar, and do a pull up. Even if you can't do a pull up, jump as high as you can and pull up as high as you can. Lower as slowly as you can from the pull up, drop back to your feet and repeat.
Position a Smith machine around hip height. It should be high enough for you to fully extend your arms without your hips touching the ground but low enough you are almost horizontal. You can also use TRX straps if they are available. Grip the bar with an overhand grip and extend your arms. Lift your hips so your body is a straight line from your head to heels. To begin: retract your shoulder blades and flex through the elbows to bring your chest to the bar. Squeeze your shoulder blades and pause, then release, slowly extending your arms back to starting position.