Ever since early people learned to walk upright, they have suffered, as an unfortunate consequence of their upright posture, from low back pain. The modern understanding of this issue dictates that low back pain is specifically caused by postural instability resulting from poor “proprioception,” a term for the perception of a portion of our body’s own position in space. In fact, our torso and lower legs are key to maintaining postural stability due to the presence of “proprioceptors” – sensory receptors that respond to position and movement – in these areas.
Elderly people suffering from low back pain tend to have poor proprioceptor performance, which is thought to affect their “proprioceptive control strategy” – a postural control strategy in response to vibration stimulation as a proprioceptive input. Interestingly, studies have suggested that local vibrational stimulation may in fact improve proprioceptive function. In previous studies by other researchers, however, its effect on postural control is still unclear. Moreover, studies do not differentiate between poor and healthy proprioceptors and do not take into account the fact that each proprioceptor has a natural vibrational response frequency.
To address these issues, a team of researchers from Japan recently conducted a study investigating the effect of local vibrational stimulation on a proprioceptive control strategy when applied to a poor proprioceptor. Prof. Yoshifumi Morita of the Nagoya Institute of Technology, Japan, who was part of a study published in Electronics, asks a research question: “Can proprioceptive function be improved for older people with low back pain? Will it cure low back pain?”
The researchers conducted their research over a 3-month period in which they recruited six elderly people, all of whom were patients with low back pain. The researchers forced each participant to stand on a balance board to assess their standing balance and attached fasteners with vibrators to the legs as well as to both sides of the torso. They then generated vibrational signals using a computer and amplified and ejected them from the vibrator as mechanical vibration stimulation. Further, they allowed the stimulation frequency to change over time, from an initial 20 Hz (cycles / second) to 300 Hz, to assess the postural response depending on the applied frequency. Finally, they compared the proprioceptive control strategy in each patient before and after stimulation of the damaged proprioceptor.
Three patients showed an improvement in the proprioceptive control strategy after their damaged muscle spindles (a proprioceptor that detects muscle stretching) responded to a higher frequency, a observation that suggests that low back pain can be alleviated in patients by activating damaged proprioceptors with vibrational stimulation. Furthermore, the device and treatment protocol can be used for multiple frequency ranges, allowing diagnosis as well as activation of a poor proprioceptor.
Given the results, the researchers are looking forward to conducting a clinical trial for a larger group of patients.
The clinical trial should start in April this year, and will be conducted for the next three years. We plan to see if the improved proprioceptive sensation can last for a long time, thus relieving older people from low back pain. “
Prof. Yoshifumi Morita, Nagoya Institute of Technology, Japan
The team hopes the test findings will soon lead to the commercialization of their device, allowing older patients with low back pain to finally breathe a sigh of relief!
Nagoya Institute of Technology
Ito, Y., and others. (2021) Method for evaluating the immediate effect of local vibrational stimulation on a proprioceptive control strategy: A pilot study. Electronics. doi.org/10.3390/electronics10030341.