The whiplash injury is most commonly associated with road traffic accidents (although is also quite common in contact sports) and occurs when an individual experiences a sudden change in velocity, usually created by impact. This rapid acceleration-deceleration mechanism of energy transfer, results in an abnormal motion within the upper thoracic and cervical region of the spine and often creates trauma to the supporting structures (muscles, facet joints and ligaments). At this point you may be asking yourself, what on earth all this has got to do with abdominal training? Many Personal Trainers and Fitness Instructors when teaching abdominal exercises, encourage their clients to support the weight of the head in the hands, or to use abdominal cradles, which provide this support externally. Such practices are usually taught with the aim of making the exercise more comfortable for the client by alleviating strain and pressure on the front of the neck.
The primary reason a client would experience discomfort in this region is largely due to a weakness of the neck flexors; by encouraging a client to support the weight of the head, the Fitness Instructor or Personal Trainer is actually further weakening the muscles in this area. The kinetic chain theory describes how the body creates movement and stability via a series of interconnected segments that are all linked together.
The muscles on the anterior surface (front) of the body are typically responsible for flexing the chain, whilst the muscles on the posterior surface (rear) are largely responsible for extending the chain. When the abdominal muscles are recruited to flex the trunk, so are the neck flexor muscles the flex (or prevent extension) of the cervical vertebrae. Thus, supporting the weight of the head during an abdominal exercise would weaken the neck flexors and create a greater strength imbalance between the abdominals and the neck flexors. When the client experiences a rapid change in velocity or impact, the neck flexor muscles will be less able to prevent the rapid extension on the cervical vertebrae which would result in a more serious grade of whiplash injury.
To prevent the weakening of the neck flexors, place the fingers on the temples or in the ears, and focus on keeping the neck neutrally aligned during the exercise. Work to the fatigue threshold of the neck flexors rather than the abdominals until the muscular imbalance between these two muscle groups is restored. Some experts also believe that by keeping the tongue on the roof of the mouth during the abdominal exercise, the neck flexor mechanism is closed making it more stable. Note: It should perhaps be noted that this principle also applies to the spinal extensors.
Core stability is another important factor in this situation; core stability differs however from traditional approaches to abdominal training because instead of focusing on training muscles individually to create movement, such exercises train muscles in an integrated fashion to oppose movements thus providing the spine and neck with greater stability.