Table 2.

Main Characteristics of the Studies Included in the Systematic Review, Including Levels of Evidence

Study	Design	Sackett's Level of Evidence	Disease	Sample Size and Gender	Age	Intervention Groups (n patients)	Duration	Frequency	Outcome Measures	Effect Size	Results
Rooyackers et al. (2003)63	RCT	IIb	COPD	20 m, 4 w	36–72	GT (n = 12): dynamic and isometric exercises, 20 min interval cycling (2 min rest + 2 min exercise)	10 weeks	5 days/week	Work output, cardiorespiratory responses, 6MWD, CRDQ	Work: GT = 0.31; GT + Ecc = 0.23	Some cardiopulmonary parameters (HR and gas exchange) improved only slightly in Ecc protocol. Patients in Ecc group were able to maintain higher work loads at reduced RPE. Work output was not significantly different between groups. GT + Ecc group slightly improved 6MWD, but GT was slightly better in the CRDQ.
										6MWD: GT = 0.69; GT + Ecc = 0.87
						GT+ Ecc (n = 12): dynamic and isometric exercises, 20 min interval cycling (2 min rest + 2 min exercise) + progressive eccentric cycling up to 15 min				CRDQ: GT = 0.90; GT + Ecc = 0.78
Meyer et al. (2003)64	RCT	IIb	CAD	13 m	40–66	Ecc (n = 7): eccentric cycling (30 min at 65% VO2peak)	8 weeks	3 days/week	Work output, cardiorespiratory responses	Work output: Ecc vs. Con = 4.45	Similar haemodynamic responses (except for the first 5′ of exercise, when Con protocol elicited lower responses in some haemodynamic parameters using four-fold power output in the Ecc group). Blood lactate accumulation was much lower in the Ecc group during exercise.
						Con (n = 6): concentric cycling (30 min at 65% VO2peak)
Steiner et al. (2004)36	RCT	IIb	CAD	12 m	44–60	Con (n = 6): concentric cycling (30 min at 60% VO2peak from week 5) plus comprehensive rehabilitation program (calisthenics, stretching, relaxation)	8 weeks	3 days/week	Muscle mass, strength, fibre size, RPE, work output	Work output: Ecc vs. Con = 5.74	Ecc group achieved a three-fold total workout compared to Con group. Strength gains were observed only in the Ecc group (isometric and concentric isokinetic at either faster or slower velocity). Fibre CSA increased only in the Ecc group. RPE related to the LEs was higher in the Ecc group, whereas the Con group showed a higher RPE related to cardiorespiratory effort.
										Strength: Ecc = 4.9% (Isom), 3.2% (Con 60), 2.5% (Con 120); Con = n.s.
						Ecc (n = 6): eccentric cycling (30 min at 60% VO2peak from week 5) plus comprehensive rehabilitation program (calisthenics, stretching, relaxation)				Muscle mass = n.s.
										Fibre size: Ecc vs. Con = 0.56
Zoll et al. (2006)67	RCT	IIb	CAD	12 m	Not reported	Con (n = 6): 30 min concentric cycling at 60% VO2peak from week 5	8 weeks	3 days/week	Mitochondrial biogenesis and function, contractile phenotype, mechanical stress markers	n.p.	COX-4 mRNA was significantly reduced and Tfam transcript concentration showed a modest drop in the Ecc group. These decreases corresponded to a reduction in total mitochondrial volume density. MyHC IIa transcript was significantly reduced and MyHC I showed a trend toward a reduction in the Ecc group. No differences were found in IGF-I mRNA levels between groups.
						Ecc (n = 6): 30 min eccentric cycling at 60% VO2peak from week 5
Dibble et al. (2006)65	RCT	IIb	PD	19	40–85	Ecc (n = 10): calisthenics, stretching, walking, cycling, lifting weights upper extremities plus high-intensity eccentric cycling (45–60 min)	12 weeks	3 days/week	Muscle volume, torque, mobility measures, LE pain (VAS), RPE	Muscle volume: (Ecc): MALE = 0.27, LALE = 0.26; (Standard): MALE = 0.04, LALE = 0.14	Greater increases in muscle volume, muscle force, and functional status in the Ecc group. Minimal LE pain in the Ecc group during the first two weeks; the rate of perceived exertion (RPE) of the LEs increased only from week 1 to week 4 in the Ecc group.
										Torque: (Ecc): MALE = 0.77, LALE = 0.73; (Standard): MALE = 0.25, LALE = 0.06
						Standard care treatment (n = 9): calisthenics, stretching, walking, cycling, lifting weights upper extremities (45–60 min)				Mobility performance: (Ecc): 6MW = 0.68, SD = 0.53, SA = 0.41; (Standard): 6MW = 0.20, SD = 0.01, SA = 0.03
Engardt et al. (1994)68	PP	IV	PD	10	40–85	Ecc (n = 10): eccentric cycling with progressively increased intensity (RPE)	10 weeks	2 days/week	Torque, muscle activity (EMG), gait, body weight distribution	Torque: (Ecc): Ecc(60) = 0.70, Ecc(120) = 0.66, Ecc(180) = 0.63; Con(60) = 0.69, Con(120) = 0.64, Con(180) = 0.60; (Con): Ecc(60) = 0.56, Ecc(120) = 0.64, Ecc(180) = 0.65; Con(60) = 0.62, Con(120) = 0.74, Con(180) = 0.84	Ecc group increased more Ecc and Con strength in the paretic LE compared to the Con group. Antagonistic activity increased after Con training only. Symmetrical body weight distribution in rising from a sitting position only after Ecc training. No differences in gait speed and duration of swing phase.
Dibble et al. (2006)34	RCT	IIb	ST	15m, 5w	54–71	Ecc (n = 10): eccentric isokinetics: repeated sets at different velocities (60–180 deg.s-1)	12 weeks	3 days/week	CK, LE pain, (VAS), isometric force, work output	n.p.	No significant CK concentrations and low pain scores (VAS). Significant increases in isometric force and total power output.
						Con (n = 10): concentric isokinetics: repeated sets at different velocities (60–180 deg.s-)
Gür et al. (2002)35	RCT	IIb	OA	23	41–75	Con (n = 9): 12 reps knee extensors-flexors	8 weeks	3 days/week	Functional capacity, pain at rest and during activities (VAS), peak torque, CSA of knee muscle groups	Total functional capacity: (Ecc/Con) = 1, (Con) = 0.88	Both training groups increased CSA and torque of knee muscles, increased functional capacity, and reduced pain scores. The Ecc/Con group showed more improvements in functional capacity, whereas the Con group showed more reduced pain scores. Non-treatment group did not show significant differences between pre- and post-tests.
										Pain: greater in Ecc group
						Con/Ecc (n = 8): 6 + 6 reps knee extensors-flexors				CSA: n.s. Con vs. Ecc/Con
						Non-treatment (n = 6)				Strength: n.s. Con. vs Ecc/Con
Harris-Love (2005)66	ICR	V	PM	1m	64	Ecc (n = 1): eccentric isokinetics: 1 week familiarization (2 sets at 80–90% RM); 2–3 weeks acclimatization (2–3 sets at 110–120% RM); 4–12 weeks progression (130–140% RM)	12 weeks	2 days/week	Peak torque knee extensors, DOMS (VAS), passive ROM, serum enzyme levels	n.p.	No exacerbation of serum enzyme levels; DOMS evaluated using VAS was non-significant. The post-training isometric and isokinetic measurements increased 48.8% and 52.6% respectively. Ability to rise from a low surface improved slightly, but the rate of fall remained unchanged.

Design: ICR = individual case report; PP = non-controlled pretest–posttest design; RCT = randomized controlled trial

Disease: CAD = coronary artery disease; COPD = chronic obstructive pulmonary disease; OA = osteoarthritis; PD = Parkinson disease; PM = polymyositis; ST = stroke

Intervention: Con = concentric exercise; Ecc = eccentric exercise; GT = general training; RM = repetition maximum

Effect Size: Con(60) = Concentric isokinetic torque at 60°/second; Con(120) = Concentric isokinetic torque at 120°/second; Isom = isometric peak; LALE = less affected lower extremity; MALE = most affected lower extremity; SD = stair descent; 6MW = 6-minutes walk test; n.p. = not provided; n.s. = non-significant

Outcome Measures and Results: CK = serum creatine kinase; CRDQ = chronic respiratory disease questionnaire; CSA = cross-sectional area; DOMS = delayed-onset muscle soreness; EMG = electromyography; IGF-1 = insulin-like growth factor 1; LE = lower extremity; MyHC = myosin heavy chain; ROM = range of motion; RPE = rating of perceived exertion; VAS = visual analogue scale; VO₂ = oxygen consumption; 6MWD = 6 minutes walking distance test