Sit-ups and other forms of abdominal isolation exercises are a common sight in gyms and outdoor workouts. Many people believe that performing repetitions of sit-ups can firm up their abdominal region or improve full-body strength. However, performing sit-ups regularly has more negative consequences than positive ones, if you do not do anything to counteract the effects of sit-ups, according to Juan Carlos Santana, director of the Institute of Human Performance.
Repetitive flexion and extension of the abdominal muscles with resistance causes your outer abs to grow in size. The microtears you create in the muscles repair themselves by forming more proteins around the muscles and connective tissues. Although sit-ups make the outer abs bigger, they do not reduce body fat from the torso and do little to improve athletic abilities, according to Santana. In fact; sit-ups can make your waistline increase because the muscle mass pushes the fat layer away from your body.
Reduce Lumbar Extension
Sit-ups flex the entire spine forward, reducing the natural extension of the lumbar spine, which is necessary to maintain normal force distribution and alignment of your joints. This causes the shortening of the muscles and connective tissues in the front of your body from your chest to your hip flexors, resulting in lower back pain, torso and hip stiffness and reduced spine and torso extension, according to physical therapist Gray Cook, author of "Movement." If you already exhibit excessive upper spine curvature, such as rounded shoulders or kyphosis, sit-ups can worsen your posture and develop disc hernia or degenerative disc disease in your spine.
Poor Core Firing
Core training is about maintaining your balance and alignment while controlling your movement patterns. This involves the autonomous activation of your stabilisers, deep inside your body and joints, to keep your spine and pelvis in place while your arms and legs move, Cook explains. Sit-ups trains the outer muscles of your abs that flexes your body forward and does very little to improve core stability and performance. This causes poor core firing, which can lead to back pain, poor posture and motor control that decreases your athletic ability.
Perform exercises that counterbalance spine flexion by performing chest, abs and hip flexor extensions to improve total-body mobility, reducing the negative symptoms of sit-ups, suggests fitness professional Anthony Carey, author of "Pain-Free Program." A sample exercise is the doorway chest stretch where you stand within a doorway with one foot in front of you, and put your forearms on the doorjamb with your elbows bent at 90 degrees. Shift your weight to your front foot which causes your body to shift forward, pulling your shoulder blades together and opening your chest and abs.
Also, most free-weight and bodyweight exercises work on abdominal stability and strength without doing sit-ups and similar exercises. These include push-ups, squats, pull-ups, medicine ball throws and kettlebell swings.