Table 5. Strength asymmetry thresholds used by the included articles (N = 53) and the evidence level of each threshold applied in the methodology of the study.

Article	Strength Asymmetry Threshold	Applied in methods? (Y/N)	Evidence Tier
Bourne et al., (2015)	Investigated asymmetries above and below 10%, 15% and 20%	Y	1
Dos’Santos et al., (2017a)	Threshold: mean + (0.2 SD of the mean) Above the threshold = abnormal Below the threshold = normal	Y	1
Dos'Santos et al., (2018)	Threshold: mean + (0.2 SD of the mean) Above the threshold = abnormal Below the threshold = normal	Y	1
Lockie et al., (2014)	Threshold: mean + (0.2 SD of the mean). Above the threshold = greater asymmetry group Below the threshold = lesser asymmetry group	Y	1
Opar et al., (2015)	Investigated asymmetries above and below 10%, 15% and 20%	Y	1
Holsgaard-Larsen et al., (2014)	Symmetry <85% and >115%=abnormal	Y	2
Fältström et al., (2017)	Symmetry <90% and >110% = abnormal	Y	3
Guney-Deniz et al., (2020)	Symmetry ≥90% = normal	Y	3
Menzel et al., (2013)	Asymmetry >15% = abnormal	Y	3
Abourezk et al., (2017)	Symmetry ≥90% = normal Symmetry <85% = abnormal	Y	4
Almeida et al., (2019)	Symmetry >10% = abnormal	Y	4
Ardern et al., (2015)	Presence of deficits on at least 2 of the following criteria: Bilateral concentric hamstring peak torque ratio of 0.86 Bilateral eccentric hamstring peak torque ratio of 0.86 Concentric hamstring-quadriceps ratio of 0.47 Mixed ratio of 0.80	Y	4
Batty et al., (2019)	Symmetry ≥90% = normal	Y	4
Clark &Mullally, (2019)	Asymmetry >10% = abnormal	Y	4
de Lira et al., (2017)	Asymmetry >15% = abnormal	Y	4
Hadzic et al., (2014)	Asymmetry >15% = abnormal	Y	4
Welling et al., (2019)	Symmetry >90% normal	Y	4
Zwolski et al., (2015)	Symmetry ≥90% = High quadriceps strength group Symmetry <90% = Low quadriceps strength group	Y	4
Chmielewski et al., (2014)	Symmetry ≥85-90% = normal	N	n/a
Costa Silva et al., (2015)	Asymmetry <15% = normal	N	n/a
Dai et al., (2019)	Asymmetry <10% = normal	N	n/a
Fort-Vanmeerhaeghe et al., (2015)	Asymmetry >10-15% = abnormal	N	n/a
Fort-Vanmeerhaeghe et al., (2016)	Asymmetry ≤10-15% = normal	N	n/a
Harput et al., (2018)	Symmetry ≥90% = normal	N	n/a
Lisee et al., (2019)	Symmetry ≥90% = normal	N	n/a
Lockie et al., (2012)	Asymmetry ≥15% = abnormal	N	n/a
Lockie et al., (2016)	Asymmetry >15% = abnormal	N	n/a
Miles et al., (2019)	Asymmetry <10-15% = normal	N	n/a
Xergia et al., (2013)	Symmetry ≥90% = normal	N	n/a
Zwolski et al., (2016)	Symmetry >90% = normal	N	n/a
Ageberg & Roos, (2016)	-	n/a	n/a
Benjanuvatra et al., (2013)	-	n/a	n/a
Bishop et al., (2019c)	-	n/a	n/a
Bishop et al., (2019d)	-	n/a	n/a
Bookbinder et al., (2020)	-	n/a	n/a
Carabello et al., (2010)	-	n/a	n/a
Coratella et al., (2018)	-	n/a	n/a
Hart et al., (2014)	-	n/a	n/a
Hiemstra et al., (2008)	-	n/a	n/a
Hubbard et al., (2007)	-	n/a	n/a
Hughes et al., (2019)	-	n/a	n/a
Kaminska et al., (2015)	-	n/a	n/a
Lloyd et al., (2020)	-	n/a	n/a
Lockie et al., (2013)	-	n/a	n/a
Madruga-Parera et al., (2019)	-	n/a	n/a
Madruga-Perera et al., (2020)	-	n/a	n/a
Maloney et al., (2017)	-	n/a	n/a
Peebles et al., (2019)	-	n/a	n/a
Redden et al., (2018)	-	n/a	n/a
Reid et al., (2007)	-	n/a	n/a
Riemann & Davies, (2019)	-	n/a	n/a
Suchomel et al., (2016)	-	n/a	n/a
Vanderstukken et al., (2019)	-	n/a	n/a

Y = Yes, N = No, n/a = not applicable, 1 = article provides the origin of the evidence for the threshold, 2 = article directly cites the origin of the evidence, 3 = article indirectly cites the origin of the evidence, 4 = article fails to provide or cite the origin of the evidence