Effects of Mental Imagery on Muscular Strength in Healthy and Patient Participants: A Systematic Review

Table 1. Effect of mental imagery in muscular strength/strength loss in healthy and patient participants.

Study	Characteristics (Age; n; Sex; Health status)	Injury	Imagery intervention	Results	PEDro scale
Herbert et al. (1998)	NR; 54; Male and female; Healthy students	No injury	Mental imagery PG Mental imagery PG (8 wks/3 dys)	-Maximal isometric contractions (elbow flexor) â†‘6.8 â†‘17.8 -Voluntary grip strength â†‘8.9 â†‘2.1 (NSDG)	7
Leung et al. (2013)	18-35; 18; Male and female; Healthy participants	No injury	Motor imagery (3 wks/3 dys)	â†‘16 Voluntary strength of the right biceps brachii	6
Smith et al. (2007)	Study 1: 20.37±3.26; 48; Male and female; Healthy student athletes Study 2: 7-14; 40; Female; Healthy athletes	No injury	PETTLEP-based imagery Traditional imagery (6 wks/1 dys) PETTLEP-based imagery (6 wks/3 dys)	Field hockey penalty flic â†‘15.11 â†‘5.59 Straight jump on the beam â†‘36.36	6
Wright and Smith (2009)	20.74±3.71; 50; NR; Healthy students	No injury	PETTLEP imagery PETTLEP + PP Traditional imagery PG (6 wks/2 dys)	1RM: bicep curl machine â†‘23.29 â†‘28.03 â†‘13.75 â†‘26.56	6
Slimani and Chéour (2016)	23.2 ± 3.1; 45; Male; Healthy participants	No injury	Mental imagery PG (10 wks/3 dys)	â†‘13.1 1RM bench press â†‘16.9 1RM half-squat â†‘10.7 1RM bench press â†‘8.61RM half-squat	6
Cupal and Brewer (2001)	28.2±8.2; 30; Male and female; Patients	Anterior cruciate ligament	Relaxation and guided imagery (10 individual sessions over 6 months; Sessions were spaced approximately 2 wks)	â†“35 Knee strength	6
Lebon et al. (2010)	19.75±1.72; 22; NR; Healthy students	Anterior cruciate ligament	Motor imagery (4 wks/3 dys)	â†‘9 Bench press â†‘26 Leg press Creater muscle activation	7
Clark et al. (2014)	Adults; 29; Female; Healthy participants	Wrist-hand immobilization	Motor imagery (4 wks/5 dys) (Four blocks of 13 imagined contractions each with 1 min of rest between the blocks; Each imagined contraction was 5 s, followed by 5 s of rest)	Maximal wrist-hand flexion â†“23.8 Loss of strength â†“12.9 Voluntary activation	8
Clark et al. (2006b)	21.00±1.41; 18; Male and female; Healthy participants	Prolonged unweighting (bed rest)	Motor imagery (4 wks/4 dys)	â†“8.5 Plantar flexor	8
Frenkel et al (2014)	20-30; 20; Male; Healthy participants	Immobilzation after distal radial fracture	Alternation of kinesthetic imagery of the immobilized hand and physical execution of the non-immobilized hand (3 wks (1 × 60 min/ 3 × 30 min) and (7 × 15 min))	Reduced loss of dorsal extension and ulnar abduction	6
Meugnot et al. (2014)	18-26; 52; Male; Student	Left-hand immobilization	Kinesthetic imagery Visual imagery (24 h (3 × 5 min each))	Slowdown of the left-hand movement simulation Reactivating the sensorimotor processes Recovery of motor function	6
Newsom et al. (2003)	18-30; 17; Male and female; Injured participants	Nondominant forearms immobilized	Immobilization-mental imagery (10 dys; 3 sessions per day; 5 min)	â†“1.33 Grip strength â†“1.28 Isometric wrist-extension â†“8.18 Isometric wrist-flexion	7
Stenekes et al. (2009)	18-65; 28; NR; Patients	Immobilzation after flexor tendon injuries	Kinesthetic imagery of finger and wrist extension-flexion (6 wks (8 × 5 min))	Reduced increase of one aspect of hand function (preparation time)	6

Wks: weeks; dys: days; PG: physical group; PP: physical practice; NSDG: no significant difference between groups; 1RM: one-repetition maximum; â†‘: increased; â†“: decreased; NR: not reported.