Table 1.

Lossless compression results

Method	Signal	Arrangement	Muscle	% of MVC
				20%	40%	60%	80%
ZIP	S k	L	UT	17.98 ± 0.59	14.69 ± 0.66
ZIP	S k	T	UT	19.78 ± 0.51	16.69 ± 0.67
JPEG	S k	L	UT	36.72 ± 0.77	31.79 ± 0.79
JPEG	S k	T	UT	36.74 ± 0.77	31.81 ± 0.78
JPEG	Δk	L	UT	40.86 ± 0.31	38.13 ± 0.40
JPEG	Δk	T	UT	40.88 ± 0.31	38.15 ± 0.41
ZIP	S k	L	MG	37.32 ± 0.89	31.73 ± 0.56	27.32 ± 0.63	25.31 ± 0.66
ZIP	S k	T	MG	38.11 ± 0.82	32.94 ± 0.50	28.71 ± 0.59	26.78 ± 0.65
JPEG	S k	L	MG	59.29 ± 1.21	52.52 ± 0.68	47.77 ± 0.59	45.40 ± 0.76
JPEG	S k	T	MG	59.30 ± 1.20	52.53 ± 0.69	47.79 ± 0.59	45.41 ± 0.77
JPEG	Δk	L	MG	58.31 ± 0.72	53.40 ± 0.53	49.88 ± 0.55	48.21 ± 0.67
JPEG	Δk	T	MG	58.31 ± 0.72	53.41 ± 0.53	49.90 ± 0.55	48.22 ± 0.67

Lossless compression of single-differential (S_k) signals and their differences in time (Δ_k). Mean values ± standard deviation of file-size reduction (%) were computed for 40 epochs per contraction level (% of MVC) of upper trapezius (UT) signals and for 8 epochs per contraction level (% of MVC) of medial gastrocnemius (MG) signals. Arrangements were longitudinal (L) and transversal (T). Methods were ZIP and lossless JPEG.