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

Table 3 Results of the eccentric RMS-EMG obtained from 76 healthy individuals that performed the cyclic submaximum lifting task. For these 76 subjects a fitted EMG dataset was available on at least one test day and the mechanical variables of test performance were comparable between age groups. Note that significant changes of the RMS-SEMG with the duration of the exercise and normalized to the onset are indicated by “*” (Bonferroni corrected sig. Level = p < 0.005)

n = 153		Intercept					Slope normalized to intercept
Level		Mean (SE)	Age F; p	Sex F; p	Age:Sex F; p	tnr F; p	Mean (SE)	Age F; p	Sex F; p	Age:Sex F; p	tnr F; p
All	< 50	0.69 (0.02)	0.1; 0.7	1.3; 0.3	2.1; 0.2	0.7; 0.4	0.35 (0.12)	2.5; 0.1	1.0; 0.3	0.8; 0.4	0.0; 1.0
All	> 50	0.71 (0.02)	0.1; 0.7	1.3; 0.3	2.1; 0.2	0.7; 0.4	0.01 (0.02)	2.5; 0.1	1.0; 0.3	0.8; 0.4	0.0; 1.0
multifidus (L5)	< 50	0.75 (0.05)	0.3; 0.6	1.7; 0.2	0.4; 0.5	0.2; 0.8	0.53 (0.23)	2.1; 0.2	0.5; 0.5	0.8; 0.4	0.2; 0.8
multifidus (L5)	> 50	0.72 (0.03)	0.3; 0.6	1.7; 0.2	0.4; 0.5	0.2; 0.8	−0.04 (0.02)	2.1; 0.2	0.5; 0.5	0.8; 0.4	0.2; 0.8
longissimus (L2)	< 50	0.71 (0.03)	0.0; 0.9	0.9; 0.3	2.6; 0.1	0.32; 0.7	0.26 (0.12)	1.0; 0.3	0.8; 0.4	0.0; 0.8	0.8; 0.4
longissimus (L2)	> 50	0.71 (0.03)	0.0; 0.9	0.9; 0.3	2.6; 0.1	0.32; 0.7	0.06 (0.03)	1.0; 0.3	0.8; 0.4	0.0; 0.8	0.8; 0.4
iliocostalis lumborum (L1)	< 50	0.61 (0.02)	5.9; 0.018	0.1; 0.8	1.9; 0.2	0.93; 0.4	0.27 (0.07)*	4.4; 0.039	1.5; 0.2	2.0; 0.2	0.5; 0.6
iliocostalis lumborum (L1)	> 50	0.69 (0.02)	5.9; 0.018	0.1; 0.8	1.9; 0.2	0.93; 0.4	0.01 (0.03)	4.4; 0.039	1.5; 0.2	2.0; 0.2	0.5; 0.6
most negative electrode	< 50	0.48 (0.02)	6.5; 0.013	0.1; 0.8	4.2; 0.045	0.85; 0.4	−0.19 (0.07)*	0.2; 0.6	0.0; 1.0	0.3; 0.6	0.4; 0.7
most negative electrode	> 50	0.56 (0.02)	6.5; 0.013	0.1; 0.8	4.2; 0.045	0.85; 0.4	−0.21 (0.02)*	0.2; 0.6	0.0; 1.0	0.3; 0.6	0.4; 0.7
uncomp. Imbalances	< 50						26.9 (3.3)	0.8; 0.4	1.9; 0.2	0.1; 0.8	0.5; 0.6
uncomp. Imbalances	< 50						22.9 (1.9)	0.8; 0.4	1.9; 0.2	0.1; 0.8	0.5; 0.6
comp. Imbalances	< 50						−0.3 (4.0)	2.0; 0.2	0.9; 0.4	0.4; 0.5	0.7; 0.5
comp. Imbalances	< 50						−8.2 (2.7)	2.0; 0.2	0.9; 0.4	0.4; 0.5	0.7; 0.5

uncomp. Uncompensated, comp. Compensated, tnr Test day, p p-value, F F-value * = p < 0.005 (indicates significant RMS-SEMG fatigue changes)

ISSN: 1743-0003