Spinal Exercises - Make use of this Amazing Research Tool
If you prescribe exercises for improving spinal mobility or strength you will find this abstract of interest, but before we get into it, you need to understand how these loads are measured. Usually due to burst lumbar fractures/tumors, participants have their VB and IVDs replaced, in this case with a vertebral body replacement e.g. Synex. Build into this replacement is a telemetry chip capable of collecting and exporting load data in vivo. This has enabled the researchers to capture load data for a huge range of ADLs and they provide all this data free. Awesome.
After spinal surgery, physiotherapeutic exercises are performed to achieve a rapid return to normal life. One important aim of treatment is to regain muscle strength, but it is known that muscle forces increase the spinal loads to potentially hazardous levels. It has not yet been clarified which exercises cause high spinal forces and thus endanger the surgical outcome. The loads on vertebral body replacements were measured in 5 patients during eleven physiotherapeutic exercises, performed in the supine, prone, or lateral position or on all fours (kneeling on the hands and knees). Low resultant forces on the vertebral body replacement were measured for the following exercises: lifting one straight leg in the supine position, abduction of the leg in the lateral position, outstretching one leg in the all-fours position, and hollowing the back in the all-fours position. From the biomechanical point of view, these exercises can be performed shortly after surgery. Implant forces similar or even greater than those for walking were measured during: lifting both legs, lifting the pelvis in the supine position, outstretching one arm with or without simultaneously outstretching the contralateral leg in the all-fours position, and arching the back in the all-fours position. These exercises should not be performed shortly after spine surgery.
You can access the whole article here.
Digging into this deeper highlighted a couple of things for me to consider. See the pictures.
The chart on the left represents the effect of single and double leg lifts and bridging while in supine. No medals for guessing that a double leg lift will increase spinal loading, more than a single leg lift, but the much higher loads associated with bridging? A common enough exercise, bridging is used to encourage gluteal and abdominal strength and for me as a quick scan for overall lumbo-pelvic 'control', but not a movement that I would have associated with such high comparative spinal loads. The research also noted the spinal loads increased with height of lift.
The second picture represents lumbar spinal loads experienced with arm, leg or combinations of both in the all fours posture. I was really surprised that single leg hip extension, resulted in much LOWER lumbar loads than shoulder flexion. Obviously an arm weights less than a leg, so weight isn't the reason. Leverage is also unlikely, as arms and leg are similar in length.
I have emphasised spinal exercises in this email, but the guys at Orthoload also have data for shoulder, hip and knee replacements which you can check out here.