Table 4.

NF MUP stability of the ST muscle

Parameter	Young	Old
MUPTs/participant	13 ± 4	18 ± 8
NF jitter, µs	37.3 ± 12.4	40.6 ± 11.6
NF jiggle, %	40.1 ± 4.7	38.8 ± 5.6
NF MUP area, kV·s−2·ms−1	9.4 ± 2.1	6.2 ± 1.4*
Mean turn area, kV·s−2·ms−1	9.4 ± 3.8	6.3 ± 2.0*
NF duration, ms	0.66 ± 0.10	0.55 ± 0.11*
NF count number	1.67 ± 0.21	1.91 ± 0.25*

Values are presented as the ensemble means ± SD; n = 20. Decomposition-based quantitative electromyography motor unit potential (MUP) stability of the superior trapezius (ST) muscle during 15% MVC. MUPTs, motor unit potential trains; NF, near fiber.

^*P < 0.05.