If there was ever an underestimated, under-assessed, under-treated (if not ignored) injury it is the whiplash, or as it is now termed whiplash associated disorder (WAD). It is termed this purely because the neck is NOT the only area of the body affected by this type of injury, any part of the body can be affected.
In fact, in my personal research, I found over 90% of patients with WAD had at least one or sometimes both hips dysfunctional (i.e weak). I have seen some bizarre results to WAD including numbness of the entire body from the ears down. As with most other injuries, the reaction to WAD varies per individual and it often depends on the history of the person involved. It is not uncommon to be treating this history as part of the treatment as the accident brings out hidden, suppressed conditions in the body that it has been accommodating to.
As an example, someone who is exercising a lot and is in a mild state of fatigue ,will most likely have a stronger reaction to the same intensity injury as does someone who lives a more sedate life. Someone who is generally unwell will respond more severely to a WAD. Someone who has had a previous injury that was untreated might find themselves re-living similar pain patterns as these are memorised and can resurface with a sufficient stress to the body.
One of the common reports after an injury of this type is that pain is seldom felt immediately after the accident. The pain often comes on slowly within a few days of the accident, however, there have been reported cases of pain manifesting many days, sometimes years after the trauma.This is what I term the 'analysis phase', where the body assesses the condition's seriousness levels and then once it feels it is stabilised, it will then release the necessary warning signs, such as pain, stiffness, dizziness, headaches, numbness, etc. The intensity of the symptoms are relative to the level of stress the body has been able to deal with and what it cannot.
One area seldom assessed in WAD is the Autonomic nervous system (ANS). This system controls all the automatic systems of the body, including sweating, hairs standing on end, heart rate, gut function etc. If this gets stressed in the injury, it is a form of concussion termed spinal concussion (similar to brain concussion). This can cause dysfunction of any of the systems it controls, such as the circulatory system, cardiac system, temperature control system and gut system. Symptoms from these can vary so much from person to person but are important indicators of where the stress is.
As for the physical strains, naturally the 'whipping' of the neck is the most common, but stress can be absorbed in many places in the body. Imagine a head-on collision with your hands on the steering wheel and feet on the pedals. Shock can go up the arms affecting the shoulders and upper back, as well as going up the legs to affect the hips and lower back. So as you can see, the whiplash associated disorders can include anything from top to tail, depending on where the body absorbs the load.
Treatment should focus on the three main systems involved, the ANS, soft tissue and muscular systems. All these need to receive attention for the recovery to be full. Now, the key to a good and full recovery is to get treatment as soon as possible. Unfortunately, a lot of insurance companies involved in road traffic accident claims delay the early intervention and thus the body compensates, further worsening the condition. If you have the chance, get treatment as soon as you can, within 24 hours if possible, and you stand a better chance of a full recovery.