Age-specific differences in the time-frequency representation of surface electromyographic data recorded during a submaximal cyclic back extension exercise: a promising biomarker to detect early signs of sarcopenia.

Only 56 of 87 tested participants had fully artefact-free EMG data across all six recording sites. The main analysis used fitted EMG data from 76 participants. Electrode detachment during the cyclic exercise caused artefacts, especially at L5 and L2. This may have reduced statistical power. The older participants were more physically active than the younger participants, with physical activity scores of 10,701 versus 5234 MET/week, and their back extension strength was similar to younger participants. This sample may not represent sedentary or frail older adults. Participants had to be independent and able to walk more than 800 m, with timed up-and-go under 10 s, tandem stand over 10 s, and chair rise under 15 s. Very disabled patients were not included. The participants were healthy volunteers, and the reported outcomes were EMG, strength, grip, activity, and fatigue ratings. Absolute reliability was highly variable for normalized slopes and EMG onset values, so day-to-day measurement error may be too large for individual decisions. The authors state that data processing must become fully automatic and absolute reliability must improve before this can be offered as a preventive diagnostic tool. Blood perfusion and muscle probes were not monitored, and the authors note this could confound spectral EMG findings.

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Do not conclude that this EMG test can diagnose early sarcopenia in your patients. It was an exploratory study in healthy volunteers, many EMG recordings were excluded or fitted, absolute reliability was variable, and the authors say the method needs further development before diagnostic use.