Peak Quadriceps Muscle Torque and Electromyographic Output in Patients With Chronic Respiratory Disorders: Effects of Pulmonary Rehabilitation.
Gregory Grandio, Guadalupe Yetter, Spencer Briglio and 5 others
PMID 37312975WHAT IT FOUND
In 8 patients who finished all testing, an 8-week pulmonary rehabilitation programme lowered the ratio of quadriceps electrical activity to force by 44% at the 4-week midpoint.
This suggests the muscles became more efficient at generating force. Strength itself did not significantly increase.
Key findings
01The ratio of peak quadriceps EMG to torque decreased significantly by 44% at the 4-week midpoint of pulmonary rehabilitation in the 8 patients who completed all three measurements.
02Peak quadriceps torque increased by 38% at the 4-week midpoint but this change did not reach statistical significance, and torque remained unchanged by the end of the 8-week programme.
03Baseline measurements showed that patients with chronic respiratory disease had significantly lower peak torque and higher EMG-to-torque ratios compared to healthy controls.
STILL TO COME
How it was doneWhat they foundWhat it means for PTs
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What it does not show
The sample size was very small, with only 8 patients completing all three physiological assessments, limiting the statistical power and generalizability of the findings. High attrition occurred due to acute illness, lack of transportation, and COVID-19 restrictions, which may have introduced selection bias if those who completed the program differed from those who dropped out. The study used peak EMG and torque values rather than integrated signals, which the authors note is a less common method in the literature. The groups were not randomized, and the control group consisted of healthy staff, not patients with respiratory disease who did not undergo PR, so direct comparisons of treatment effects are limited. Quality of life data was only available for 6 patients, making it difficult to draw firm conclusions about the relationship between physiological changes and patient-reported outcomes.
The easy way to misread this
Do not interpret the significant decrease in the EMG-to-torque ratio as evidence of improved muscle strength. The peak torque itself did not increase significantly, so the finding reflects improved neuromuscular efficiency or reduced fatigue, not necessarily a gain in force-generating capacity.