Table 3.

Main information of the studies selected in this review. Single session and Longitudinal studies (in gray), Other pathologies.

Study	DIS	IL	CS	N Task	N Cond	PAT	HS	MUS	ALGO	ΔN	ΔW	ΔC
Tang et al., 2017	CP	FMA 28-61	Yes	3	1 (free)	14 (9 + 5); 8.2	10 (3 + 7); 8.9	10	NMF	A fewer number of synergies were recruited in CP group.	Many abnormal synergy structures specific to the CP appeared. A lower intra-group similarity was observed in the CP group.	A lower synergy activation similarity was observed in the CP group, while both were very low compared to the synergy similarity.
Li et al., 2019	CP	GMFCS 1-4	/	1	1 (free)	11 (7 + 4); 4.68	9 (8 + 1); 5.83	12	NMF	/	Synergy structure had greater repeatability than activation curves in both the TD and CP groups.	For both muscle synergies and synergy activations, the mean similarity values of the CP group were significantly lower than those of the TD group.
Shimizu et al., 2019	CP	GMFCS 3-4	/	1	1 (free)	2 (2 + 0); 18	0	4	NMF	/	/	/
Zariffa et al., 2012	SCI	UEMS 21–25/25	Yes	8	1 (free)	6 (6 + 0); 49.2	10 (10 + 0); 34.9	8	NMF	/	Healthy subjects showed more co-activation of EDC and EIP, and of FDS and FCU. In contrast, the co-activation of ECR and FCR was more common among SCI subjects.	/
Muceli et al., 2014	MP	/	/	12 × 2	1 (free)	0; -	8 (8 + 0); 29.3	12	NMF	The number of synergies was consistent in all conditions.	The injection of hypertonic saline had a major influence on the first synergy, mainly activating the DEA. The synergies related to the coupling of the elbow and shoulder joints were usually preserved across subjects.	The injection of hypertonic saline changed the activation signals, especially in the first synergy, a lower peak value was observed compared to the baseline level.
Jiang et al., 2014	AMP	/	/	2	1 (free)	7 (7 + 0); 14-72	7 (4 + 3); 25-56	7–8	NMF	/	/	/
Heales et al., 2016	LE	PRTEE 37.7/100 (mean)	/	4	1 (free)	12 (4 + 8); 51.6	14 (5 + 9); 51.4	6 + 6	NMF	Two synergies were extracted from both groups.	There was no difference in muscle synergies between arms in the LE group. When the synergies extracted from pooled data of the control group were used to reconstruct the muscle activation of both groups, a significantly higher VAF was observed in the control group.	/
Lunardini et al., 2017	DYS	TOTAL 2-10	/	2	1 (free)	9 (6 + 3); 13.4	9 (2 + 7); 15.7	8	NMF	A similar number of synergies was extracted from both groups.	Muscle synergies were greatly similar between groups.	The activation profile did not significantly differ between groups, while the amplitude of the peaks presented a slight reduction in the dystonia group.
Pellegrino et al., 2018	MS	EDSS 2.5–6.5/10	/	8	4 (four force levels)	11 (2 + 9); 50	11 (2 + 9); 50	15 + 15	NMF	The number of synergies was not significantly different between populations.	MS subjects presented a higher change in the organization of muscle synergies in the presence of external forces environment.	The correlation between activation profiles of two different tasks was significantly different between groups, and this difference depended also on the pair of tasks compared.
Essers et al., 2019	FSHD	BSS 3-4	/	2	1 (free)	11 (6 + 5); 54	11 (5 + 6); 55	8	NMF	Two synergies were extracted from both groups.	Muscle synergies altered in FSHD individuals and showed greater diversity while controls mostly used one synergy for both tasks.	/
Hu et al., 2019	PD	UPDRS 11–25/56	/	1	2 (with or without CAS)	10 (8 + 2); 63.7	8 (6 + 2); 63.13	6	NMF	Three synergies were extracted from both groups.	Muscle synergies were more similar in both groups with and without CAS.	Synergy activations displayed some oscillatory components in PD patients and the similarity with and without simulation was smaller than in the control group.
McClanahan et al., 2020	AMP	DASH 1.67–86.67	/	40	1 (free)	40 (28 + 12); 29.9	11 (11 + 0); 42.36	8–12	NMF	Male subjects exhibited a larger number of synergies than female subjects in able-bodied subjects. Amputees exhibited less than four synergies, whereas able-bodied subjects commonly demonstrate five or more synergies.	/	/
Berger et al., 2020	CA	ICARS 12-55	Yes	8	1 (free)	11 (5 + 6); 44.4	11 (6 + 5); 49.7	13	NMF	/	Cerebellar damage affects the temporal and spatiotemporal organization, but not the spatial organization, of the muscle patterns.	Cerebellar damage affected the temporal and spatiotemporal organization of synergy activations.
Leonardis et al., 2021	SIBR	/	/	40	1 (free)	14 (0 + 14); -	10 (0 + 10); -	16 + 16	NMF	/	Two out of three synergies were more similar than chance between the groups on the non-dominant arm, whereas only one synergy is more similar than chance on the dominant arm.	/
Pierella et al., 2022	MS	EDSS 0-1	/	8	4 (four force levels)	7 (3 + 4); 42	7 (3 + 4); 42	15	NMF	The two populations had the same number of muscle synergies.	The two populations had similar structures of muscle synergies.	The two populations had different activation profiles.