Since 1989, there have been a number of scientific studies conducted to test various aspects of Nada-Chair's back support system addressing the following questions:
- Do Nada-Chair's back supports improve posture and restore natural back curves?
- Can these products prevent musculoskeletal disorders?
- Is there a decrease in muscle activity in the back pointing to a more relaxed posture?
- How do users experience the difference in posture with and without the supports?
- Is the pressure placed on the knees acceptable?
- Does the driving version (LumbarJack) inhibit critical movement of legs for driving?
Some of the early studies were conducted in a university setting by students earning their medical degrees. Others have been conducted by independent institutes and clinics. At least one foreign study, in Japanese, has not yet been translated into English.Physical Therapy Studies:
In April 1989, two studies were completed at Schools of Physical Therapy in Canada and US. Both were designed to test the manufacturer's claims regarding their products improving posture. The Canadian study analysed photographs of subjects sitting with and without the Nada-Chair. Further, subjects filled in a questionnaire regarding their experience of the product. The US study measured the lumbar curve of subjects first while standing and then while sitting both with and without the Nada-Chair. Both of these studies prove the manufacturer's claims that the Nada-Chair provides a significant improvement in lumbar lordosis which, in turn, leads to better sitting posture.Clinical Resources Study:
In 1995, the Journal of Occupational Rehabilitation published a study by two California researchers in the field of sEMG. The Effects of Chair Design on Back Muscle Fatigue were studied by use of electromyographic instruments that measure the activity of paraspinal muscles on seated subjects. The researchers were interested in what effect the use of the Nada-Chair would have the level of muscle activity required for sitting. They had sitting subjects tested to make comparisons among 1) a standard ergonomic office chair, 2) the so-called kneeling chair (Balans chair) that has no back and 3) finally using the Nada-Chair. The results showed a significant reduction in muscle activity in the mid and upper back as well as a reduction in the lumbar area when using the Nada-Chair.LumbarJack Study:
With the 1993 introduction of the LumbarJack support for driving, it was imperative to prove the product would not inhibit the user in movements required to drive safely. Braking Reaction-Time Wearing the LumbarJack Back Support System demonstrated "there was no general reaction-time effect of wearing the LumbarJack". Actual measured braking times were insignificantly faster for those wearing the the LumbarJack support.TNO Study:
A Dutch institute in Leiden conducted a study, Evaluation of a Sitting Aid: the Back-Up, including both objective and subjective measures. While some of the EMG findings of this study stand challenged by a study published later with larger samplings, (this study's subject sampling involved only 2 healthy males in the first study and 5 each, males and females in the second), it does include a useful study of knee pressures. Results led to a modification and re-test of the Back-Up using cushions (now sold as accessory CushShins) that widened the area of pressure dispersion on the knee/shin. This improvement resulted in a significant perceived increase in comfort on the knees as well as "positive objective and subjective effects on the posture of the neck and upper back and no unacceptable effects on the other parts of the body...."