Effects of cognitive loading on lumbar flexion relaxation phenomenon in healthy people.
Mohammad Pouretezad, Reza Salehi, Hossein Negahban and 2 others
PMID 29950757WHAT IT FOUND
Healthy participants bending forward while doing a hard digit memory task showed less lumbar muscle relaxation; an easy task did not change it.
Key findings
01The difficult cognitive task produced significantly lower flexion relaxation ratio values on both sides during forward bending (p<0.01).
02The easy cognitive task did not significantly change flexion relaxation ratio values compared with no task (p=0.96 for left to p=0.22 for right).
03The extension phase flexion relaxation ratio was not significantly changed except for the left side in the difficult task compared with no task (p=0.02).
STILL TO COME
How it was doneWhat they foundWhat it means for PTs
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What it does not show
The study included 22 healthy volunteers, so it cannot show effects in people with low back pain or other patients. Only 4 women were included, and the authors note this makes generalisation to female populations difficult. The sample was recruited by convenience sampling, not a probability method. The text does not report how the three cognitive conditions were ordered or whether order effects were controlled. Several comparisons were not significant, especially in the extension phase, and the authors suggest small sample size may explain this. The easy cognitive task did not produce a significant effect, so the result applies to the difficult task condition.
Declared interests
The study was part of a PhD thesis and was supported by a grant from the Musculoskeletal Rehabilitation Research Center, Ahvaz Jundishapur University of Medical Sciences. The authors declared no conflict of interest.
The easy way to misread this
Do not read the lower flexion relaxation ratio as proof that cognitive loading causes back injury or that patients should be treated differently. The study involved 22 healthy people, and only the difficult flexion result was significant.