Table 3.

Comparison of the difference in improvement of observed indexes between IDD patients with sarcopenia and without sarcopenia after IFC therapy (x ± s)

	IWS	IWOS	P	ES
Number of cases	34	86
Grip strength	6.31 ± 4.22	0.76 ± 2.32	0.000	1.630
GS	0.25 ± 0.15	0.16 ± 0.16	0.003	0.580
SMI	0.49 ± 0.86	0.35 ± 0.81	0.431	0.168
SARC-F	-2.00 ± 1.44	-0.10 ± 1.36	0.000	1.357
SCAS	1.93 ± 23.27	-2.57 ± 20.72	0.303	0.204
DFF	0.05 ± 3.15	-0.36 ± 3.51	0.561	0.123
VAS	-4.59 ± 1.99	-4.85 ± 1.91	0.507	0.133
ODI	-6.12 ± 4.11	-1.66 ± 4.01	0.000	1.098
NVC	1.51 ± 6.04	0.67 ± 5.71	0.474	0.143

After IFC stimulation, the improvement of grip strength, GS, ODI and SARC-F in IWS group were greater than IWOS (P < 0.05), whereas there was no significance in improvement degree of other indicators between the two (P > 0.05); *P < 0.05, statistically significant differences. All the comparisons were performed between two groups, the detailed information was indicated in the table (two-tailed, Student’s t test). Effect size was presented by Cohen’s d. Cohen’s d: 0–0.2 small; 0.3–0.5 moderate; ≥ 0.6 large

GS Gait speed, SMI Skeletal muscle index, SARC-F S (Strength), A (Assistance in walking), R (Rise from a chair), C (Climb stairs), F (Falls), SCSA Standard cross-sectional area, DFF Degree of fatty infiltration, VAS Visual analogue scale, ODI Oswestry dysfunction index, NCV Nerve conduction velocity, IDD Intervertebral disc degeneration, IFC Interferential current, IWS Intervertebral disc degeneration patients with sarcopenia, IWOS Intervertebral disc degeneration patients without sarcopenia, ES Effect size