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Table 2 Characteristics and results of experimental studies with strength training for patients with fibromyalgia syndrome

From: A systematic review of the effects of strength training in patients with fibromyalgia: clinical outcomes and design considerations

Study and Design Sample Intervention Results Conclusion
Hakkinen et al., (2001); RCT 21 women with FM (ST and CG) e 12 HC
Age
TF: 39 ± 6 years
CG: 37 ± 5 years
GS: 37 ± 6 years
Duration: 21 weeks;
Weekly frequency: 2; Repetitions: Initially 15–20, from the 15th week; 5–10
Exercises: Supine, squats, extension and flexion of knees and trunk
Adherence to ST: 100%
FM subjects increased their maximal and explosive strength and EMG activity to the same extent as the HC group. Moreover, the progressive strength training showed immediate benefits on subjectively perceived fatigue, depression, and neck pain of training patients with FM. A similar maneuverability of the neuromuscular system occurs in women with FM and healthy women. ST is safe and can be used to decrease the impact of FM in the neuromuscular system
Hakkinen et al., (2002); RCT 21 women com FM, (ST and CG) and 12 HC
Age
TF: 39 ± 6 years
CG: 37 ± 5 years
GS: 37 ± 6 years
Duration: 21 weeks;
Weekly frequency: 2; Series: 3–5 series per exercise; Intensity: 40–80% of 1RM; Repetitions: Initially 10–20, from the 14th week; 5–8.
Exercises: leg press, extension and flexion of the knee, elbow and trunk, pulled high, adduction and abduction of the legs
Adherence to ST: 100%
Maximal force increased by 18 ± 10% in the FM group, and by 22 ± 12% in the HC, while in the CG it remained unchanged. Maximum integrated EMG of the agonists (VL + VM/2) increased in HC by 22% and in the FM by 19%. Significant increases in the CSA of the QF were observed at 5 to 12/15 femur in FM and at 3 to 12/15 femur in HC, while in FM the CSA remained unchanged. A significant acute increase took place in the mean concentration of GH at pre-training in HC and in the FM, while at post-training the elevations after the loading remained elevated up to 15 min in HC and up to 30 min post-loading in the FM. The time of neuromuscular and ST adaptations and the basal levels of anabolic hormones in women with FM are similar to healthy women
Jones et al., (2002); RCT 68 women (ST and FLEX);
Age
TF: 49.2 ± 6.36 years
CG: 46.4 ± 8.56 years
Duration: 12 weeks;
Weekly frequency: 2 Initially 1 series of 4–5, and progressively up to 12. Exercises: The main muscle groups were worked, but exercises were not specified.
Adherence to ST:85%
No statistically significant differences between groups were found on independent t tests. Paired t tests revealed twice the number of significant improvements in the strengthening group compared to the stretching group. Effect size scores indicated that the magnitude of change was generally greater in the strengthening group than the stretching group. The ST group decreased the total pain score, the number of tender points, increased leg strength, shoulder strength, improved quality of life and reduced depression. ST showed better results than FLEX.
Valkeinen et al., (2004); RCT 36 women (26 FM and 10 HC)
Age
ST: 60.2 ± 2.5 years
CG: 59.1 ± 3.5 years
HC: 64.2 ± 2.7 years
Duration: 21 weeks;
Weekly frequency: 2; Initially 3 series of 15–20 progressively up to 4 series of 8–12 and up to 5 series of 5–10 .
Exercises: The main muscle groups were worked, but exercises were not specified.
Adherence to ST: 100%
The mean increases in maximal extension force during the training period in groups FM and in HC were 32 ± 33% and 24 ± 12% respectively and those of flexion were 13 ± 20% and 24 ± 17%. Explosive force of the extensors increased in both FM and in HC. The integrated EMGs of the vastus lateralis and medialis muscles increased in both FM and HC. Muscle forces and EMGs in group CG remained at the basal level. Walking speed, stair-climbing time and the HAQ index improved in group FM. The changes in the number of tender points and in perceived symptoms were in favors of the training group FM. It improved the functional capacity and the strength in the extensor and flexor muscles of the knee in both groups submitted to the TF (FM and healthy). Patients with FM respond similarly to TF that healthy people of the same age.
Valkeinen et al., (2005); RCT 26 women (ST and CG);
Age
ST: 60 ± 2 years
CG: 59 ± 4 years
Duration: 21 weeks;
Weekly frequency: 2; Initially 3 series of 15–20; weeks 15 to 21 went to 5–10. Intensity: progressive increase of 40% to 80% of 1 RM Exercises: 6 to 7 for the main muscle groups
Adherence to ST: not reported the number of dropouts
All patients were able to complete the training. In FM strength training led to increases of 36% and 33% in maximal isometric and concentric forces, respectively. The CSA increased by 5% and the EMG activity in isometric action by 47% and in concentric action by 57%. Basal serum hormone concentrations remained unaltered during strength training. The subjective perceived symptoms showed a minor decreasing tendency (ns). No statistically significant changes occurred in any of these parameters in CG. The ST increases strength, cross-sectional area and voluntary muscular activation in elderly women with FM. Patients with FM can be submitted to higher intensities without increasing symptoms
Kingsley et al., (2005); RCT 29 women (ST and CG);
Age
ST: 45 ± 9 years
GC: 47 ± 4 years
Duration: 12 weeks;
Weekly frequency: 2; 1 serie of 8–12
Intensity: 60 to 80% of 1RM
Exercises: Supine, extension and flexion of knee and elbow, low row, shoulder and lumbar development
Adherence to ST: 54%
The strength group significantly improved upper and lower body strength. And upper-body functionality measured by the Continuous-Scale Physical Functional Performance test improved significantly after training. Tender point sensitivity and fibromyalgia impact did not change. At the end of study was a significant increase in muscle strength and improvement in functional capacity components in the ST group.
Valkeinen et al., (2006); Non RCT 23 women (13 ST and 10 CG)
Age
ST: 60 ± 2 years
CG: 54 ± 3 years
Duration: 21 weeks;
Weekly frequency: 2 Intensity: Started with 50% of 1RM and progressively up to 80%; Exercises: two Exercises for knee extensors and 4–5 Exercises for the rest of the body
Adherence to ST: 100%
The ST led to large increases in maximal force and EMG activity of the muscles and contributed to the improvement in loading performance (average load/set) at week 21. The fatiguing loading sessions typically applied in strength training before and after the experimental period caused remarkable and comparable acute decreases in maximal force and increases in blood lactate concentration in both groups. Acute exercise-induced muscle pain increased similarly in both groups, and the pain level in women with FM was lowered after the 21-week training period. An increase in maximal strength, blood lactate concentration and decrease in pain of the ST group was observed.
Bircan et al. (2008); RCT 26 women (ST and AE)
Age
ST: 46 ± 8,5 years
AE: 48.3 ± 5.3 years
Duration: 8 weeks
Weekly frequency: 3 Initially 1 serie of 4 repetitions and progressively up to 12 repetitions; Exercises were not specified, however, free weights were used and the patient’s body weight
Adherence to ST: 100%
There were significant improvements in both groups regarding pain, sleep, fatigue, tender point count, and fitness after treatment. HAD-depression scores improved significantly in both groups while no significant change occurred in HAD-anxiety scores. Bodily pain subscale of SF-36 and physical component summary improved significantly in the AE group, whereas seven subscales of SF-36, physical component summary, and mental component summary improved significantly in the ST group. Aerobic exercise and strengthening exercise were similarly effective at improving symptoms, tender point count, fitness, psychological status, and quality of life in fibromyalgia patients.
Figueroa et al. (2008); RCT 19 women (10 FM and 9 HC)
Age
ST:50 ± 10 years
HC: 49 ± 8 years
Duration: 16 weeks
Weekly frequency: 2
1 serie of 8–12 repetitions; Intensity: Initially 50% 1RM and progressively up to 80%;
Exercises: Supine, knee extension and flexion, Leg press, low row, shoulder development (performed on machine)
Adherence to ST: 67%
RR interval, total power, log transformed (Ln) squared root of the standard deviation of RR interval (RMSSD), low-frequency power and BRS were lower, and HR and pulse pressure were higher in women with FM than in healthy controls. After ST, mean (SEM) total power increased, RMSSD increased and Ln of high-frequency power increased in women with FM. Upper and lower body muscle strength increased by 63% and 49%, and pain perception decreased by 39% in women with FM. There were no changes in BRS, HR and BP after ST. The ST improves heart rate variability, parasympathetic activity, pain and the strength of women with FM with autonomic dysfunction.
Kingsley et al. (2009); Non RCT 18 women (FM and HC)
Age
48,0 years (21–59 years)
Duration: acute effect
One session
30 min of ST, 1 serie of 12;
Exercises: 10 exercises, were not specified.
Adherence to ST: 100%
Variables were similar in both groups at rest. HFnu decreased in controls and increased in women with FM post. LFnu increased in controls and decreased in women with FM. The LFnu/HFnu ratio increased in controls with no change in women with FM, and BRS decreased in controls but not in women with FM. The results showed lower muscle strength in the FM group and after acute ST, women with FM responded differently from controls, demonstrated by lower sympathetic and higher vagal modulation without altering baroreceptor reflex sensitivity.
Panton et al. (2009); RCT 21 women (ST e ST-C);
Age
ST: 50 ± 7 years
ST-C: 47 ± 12 years
Duration: 16 weeks;
Weekly frequency: 2; 1 serie of 8–12 repetitions; Exercises: Supine, knee extension and flexion, Leg press, low row, shoulder development (performed on machine).
Adherence: 82.8%
Both groups increased upper and lower body strength. There were similar improvements in FM impact in both groups. There were no group interactions for the functionality measures. Both groups improved in the strength domains; however, only ST-C significantly improved in the pre- to postfunctional domains of flexibility, balance and coordination, and endurance. The ST improved FM impact on quality of life and strength. The practice of chiropractic in conjunction with TF assisted in adherence and functional capacity
Kingsley et al. (2010); Non RCT 29 women (9 FM and 20 HC)
Age
FM: 42 ± 5 years;
HC: 45 ± 5 years
Duration: 12 weeks;
Weekly frequency: 2; 3 series of 12 repetitions; Intensity: Initially 50% 1RM and progressively up to 85%; Exercises: Supine, extension and flexion of the knee, Leg press, low row (performed in machine)
Adherence to ST: 88%
There was no group-by-time interaction for any variable. Number of active tender points, myalgic score, and FIQ score were decreased after ST in women with FM. Heart rate and natural log (Ln) high frequency (LnHF) were recovered, whereas Ln low frequency (LnLF) and LnLF/LnHF ratio were increased 20 min after acute leg resistance exercise. There were no significant effects of ST on HRV at rest or postexercise. The ST increased strength in both groups and reduced pain and number of PT in patients with FM. The practice of ST does not change the resting HR, nor the variability of HR compared to healthy subjects.
Kingsley et al. (2011); Non RCT 23 women (9 FM and 14 HC);
Age
FM: 42 ± 5 years
HC: 45 ± 5 years
Duration: 12 weeks;
Weekly frequency: 2; 3 series of 12 repetitions; Intensity: Initially 50–60% 1RM Exercises: Supine, extension and flexion of the knee, Leg press, low row (performed in machine)
Adherence to ST: 88%
Aortic and digital diastolic blood pressure (DBP) were significantly decreased and aortic and digital pulse pressures (PP) were significantly increased after acute exercise before ST. Acute resistance exercise had no effect on HR, wave reflection (augmentation index and reflection time), digital, or aortic systolic BP. ST improved muscle strength without affecting acute DBP and PP responses. The results suggest that a leg-resistance exercise produces post-exercise diastolic hypotension and does not alter aortic systolic blood pressure and HR. In addition, vascular responses at rest and post-exercise are not altered after 12 weeks of ST in premenopausal women
Kayo et al. (2012); RCT 90 women with FM (30 ST, 30 AE and 30 CG)
Age
ST: 46.7 ± 6.3 years;
AE: 47.7 ± 5.3 years;
CG: 46.1 ± 6.4 years
Duration: 16 weeks;
Weekly frequency: 3; 3 series of 10 repetitions;
Exercises were not specified, however, free weights were used and the patient’s body weight
Adherence to ST: 73,5
All 3 groups showed improvement after the 16-week treatment compared to baseline. At the 28-week follow-up, pain reduction was similar for the AE and ST groups, but different from the control group. At the end of the treatment, 80% of subjects in the control group took pain medication, but only 46.7% in the AE and 41.4% in the ST groups. Mean FIQ total scores were lower for the AE and ST groups compared with the control group. The ST was as effective as AE in reducing pain in relation to all study variables.
Hooten et al. (2012); RCT 72 FM (36 ST and 36 AE)
Age
ST 47.3 ± 10.1 years
AE 45.8 ± 11.5 years
Duration: 3 weeks;
Weekly frequency: 2; 1 serie of 10 repetitions;
Exercises: Flexion and extension of the knee and arm
Adherence to ST: 94,5%
Significant improvements in pain severity, peak Vo2, strength, and pain thresholds were observed from baseline to week 3 in the intent-to-treat analysis; however, patients in the aerobic group experienced greater gains (in peak Vo2) compared to the strength group. The ST was effective in reducing pain in relation to all study variables. ST practice reduced pain significantly, but there was no difference in relation to AE.
Gavi et al. (2014); RCT 76 FM (35 ST and 36 FLEX)
Age
ST: 44.34 ± 7.94 years
FLEX: 48.65 ± 7.60 years
Duration: 16 weeks;
Weekly frequency: 2; 1 serie of 10 repetitions; Intensity: 45% 1RM Exercises: Supine, extension and flexion of the knee, elbow and shoulder, Leg press, low paddling, fly, plantar flexion
Adherence to ST: 87,5%
The ST group was more effective to strength gain for all muscles and pain control after 4 and 16 weeks. The FLEX group showed higher improvements in anxiety. Both groups showed improvements in the quality of life, and there was no significant difference observed between the groups. There was no change in the HRV of the ST and FLEX groups. There was an increase in functionality, depression, quality of life in both groups, with no statistical difference between them. There was greater reduction of pain in the ST group.
Larsson et al. (2015); RCT 130 FM (67 ST, 63 RT)
Age
ST: 50.81 ± 9.05 years;
RT: 52.10 ± 9.78 years
Duration: 15 weeks
Weekly frequency: 2 Intensity: increased progressively
Exercises: The main muscle groups were worked, but exercises were not specified.
Adherence to ST: 71%
Significant improvements were found for isometric knee-extension force, health status, current pain intensity, 6MWT, isometric elbow flexion force, pain disability, and pain acceptance in the ST group when compared to the CG. Differed significantly in favor of the ST group at post-treatment examinations. No significant differences between ST group and the active CG were found regarding change in self-reported questionnaires from baseline to 13–18 months. The ST was considered a viable exercise mode for women with FM, improving muscle strength, with a significant improvement in health-related quality of life and current pain intensity, when assessed immediately after the intervention.
Palstam et al. (2016); Non RCT 67 women com FM (67 ST)
Age
51 ± 9.1 years
Duration: 15 weeks;
Weekly frequency: 2; Intensity: Initially 40% 1RM and progressively up to 80%;
Exercises: The main muscle groups were worked, but exercises were not specified.
Adherence to ST: 71%
Reduced pain disability was explained by higher pain disability at baseline together with decreased fear avoidance beliefs about physical activity. The improvements in the disability domains of recreation and social activity were explained by decreased fear avoidance beliefs about physical activity together with higher baseline values of each disability domain respectively. The improvement in occupational disability was explained by higher baseline values of occupational disability. The ST reduces pain, inability and fear of practicing Physical exercises and increased strength and level of physical activity.
Ericsson et al. (2016); RCT 105 women (56 ST and 49 RT)
Range of age 22–64 years
Duration: 15 weeks;
Weekly frequency: 2; Intensity: Initially 40% 1RM and progressively up to 80%;
Exercises: The main muscle groups were worked, but exercises were not specified.
Adherence to ST: 71%
A higher improvement was found at the post-treatment examination for change in the ST group; as compared to change in the active CG in the MFI-20 subscale of physical fatigue. Sleep efficiency was the strongest predictor of change in the MFI-20 subscale general fatigue. Participating in resistance exercise and working fewer hours per week were independent significant predictors of change in physical fatigue. The ST group significantly reduced general, physical and mental fatigue and improved sleep efficiency in relation to the relaxation group; depression and anxiety did not decline after the intervention
Martinsen et al. (2017);
Non RCT
54 women (31 ST and 23 HC)
Age
ST: 49 ± 6
HC: 47 ± 2
Duration: 15 weeks
Weekly frequency: 2
Exercises: exercises were not specified.
Adherence to ST: 65,5%
The FIQ ratings decreased following exercise in patients with FM, suggesting an improvement of FM symptoms. Furthermore, for the SF-36 PCS ratings we found a statistically significant effect of group and intervention, but no significant interaction between the factors, thus showing that exercise improved ratings of SF-36 PCS in both groups. The intervention had different effects on the speed of cognitive processing during SCWT in patients with FM and healthy controls. We found evidence of increased amygdala activation. In contrast, HC showed decreased RTs in incongruent and congruent stimuli. Exercise had no effect on distraction-induced analgesia or pressure pain thresholds in any of the groups but decreased the overall severity of FM symptoms.
Andrade, Vilarino e Bevilacqua (2017); Non RCT 52 FM (31 ST and 21 CG)
Age
ST: 54.42 ± 7.16
CG: 53.10 ± 8
Duration: 8 weeks
Weekly frequency: 3 Exercises: knee extension, knee flexion, bench press, fly, adductors, low rowing, high pulley, elbow extension, lateral raise, arm curl, standing calf raise, and abdominal crunch.
Adherence to ST: 81,5
After 8 weeks of intervention, significant differences were found between groups in subjective quality of sleep, sleep disturbance, daytime dysfunction, and total sleep score. The correlation analysis using Spearman’s test indicated a positive relationship between the variables of pain intensity and sleep quality; when pain intensity increased in patients with fibromyalgia, sleep quality worsened. A significant relationship was found between pain level and sleep disturbances in FM patients, and it was found that the higher the pain, the worse the sleep quality of these patients. The ST group reduced levels of sleep disturbance after 8 weeks of intervention.
Assumpção et al. (2017); RCT 53 FM (19 ST, 18 FLEX E 16 CG)
Age
ST: 45.7 ± 7.7
FLEX: 47.9 ± 5.3
CG: 46.9 ± 6.5
Duration: 12 weeks
Weekly frequency: 2
Exercises: eight repetitions of strengthening exercises for the following muscles triceps sural, hip adductors and abductors, hip flexor, shoulder flexor and extensor, anterior and posterior deltoids, pectoralis major and rhomboids
Adherence to ST: 89,5%
The ST group had the lowest depression score and; the control had the highest score of morning tiredness and stiffness, and the lowest score of vitality. In the clinical analyses, the stretching group had important improvement in quality of life for all SF-36 domains, and the strengthening group had important improvements in the impact on FM symptoms measured by the FIQ total score and in the quality of life for SF-36 domains of physical functioning, vitality, social function, role emotional and mental health. The ST was more effective to reducing depression, while stretching exercises was better to improving quality of life, especially physical functioning and pain.
  1. LEGEND: FM Fibromyalgia, HC Healthy Control, RCT Controlled and Randomized Study, TP Tender Points, AE Aerobic Group, RT Relaxation Therapy, RM 1 Maximum Repeat, ST Strength Training, ST-C Strength Training and chiropractic, FLEX Flexibility training, HR Heart Rate, HRV Heart Rate Variability, CG Control Group, NMS Neuro-muscular system, SCWT Test of colored words Stroop, RTs long reaction times, FIQ Fibromyalgia Impact Questionnaire, SF-36 36- Item Short Form Survey, PCS Physical Component, MCS Mental Components, HAD Hospital Anxiety and Depression Score, 6MWT 6 min walking test, PGIC patient global impression of change, VAS Visual Analogue Scale, MFI-20 Multidimensional Fatigue Inventory, CSA cross-sectional area, QF quadriceps femoris, LF low-frequency, GH growth hormone, HAQ Health Assessment Questionnaire, EMG Surface electromyographic, Hfnu normalized high-frequency, Lfnu normalized low-frequency, RTs reaction times