Muscle excitability testing: Age and sex dependency of normative data

Figures

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  Fig. 1. MVRC and frequency ramp. (A) Top: Mean MVRC recordings for 1, 2 and 5 conditioning stimuli, indicating the parameters MRRP (muscle relative refractory period), ESN (early supernormality) and LSN (late supernormality). Bottom: Mean differences between 2 and 1 (2–1) and between 5 and 1 (5–1) conditioning stimuli, indicating the parameters XLSN (extra late supernormality for 2) and 5XLSN (extra late supernormality for 5 conditioning stimuli).(B) Mean frequency ramp recordings, showing changes in latency for the first and last responses in a train as frequency was increased to 30 Hz.

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  Fig. 2. Age-related changes in muscle excitability. Scatter plots illustrating age-related changes in A: muscle relative refractory period (MRRP), B: early supernormality (ESN), and C: latency to the first response in train at 15 Hz (Lat(15 Hz)first) for the age groups 21–60 (grey) and 61–77 years (black). Lines are regression lines ± SD and R values correlation coefficients.

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  Fig. 3. MVRCs and frequency ramps in younger and older subjects. (A) Top: MVRC recordings with single conditioning stimulus in healthy subjects aged 21–60 and 71–77 years (mean ± SE). Bottom: Mean differences between 2 and 1 and between 5 and 1 conditioning stimuli (means ± SE) as in Fig. 1A. (B) Frequency ramps as in Fig. 1B, compared between ages 21–60 and 71–77 (mean ± SE).