ABSTRACT
BACKGROUND AND OBJECTIVES:
Fibromyalgia syndrome (FMS) is characterized by different factors, such as chronic diffuse muscle pain (CDMP), fatigue and psycho-emotional changes. Among the animal models that mimic FMS, the acid saline model is consolidated in the development and maintenance of CDMP. Resistance training (RT) has been an effective method for reducing pain in FMS. Thus, the aim of the present study was to evaluate the effects of resistance training on nociceptive and motor responses in an animal model of chronic diffuse muscular pain.
METHODS:
Twenty-four male Wistar rats were allocated into four groups: resistance training, RT control, amitriptyline (AMITRIP) and AMITRIP control; all treatment protocols lasted 4 weeks. CDMP was induced in all mice. Then, the animals were treated with low-intensity RT (40% 1 maximum repetition) and AMITRIP (10 mg/kg/day). The mechanical paw withdrawal threshold, locomotor activity and muscle strength were evaluated.
RESULTS:
Animals treated with both RT and AMITRIP showed an increase in the mechanical paw withdrawal threshold (p<0.05) compared to their controls, suggesting a reduction in mechanical hyperalgesia. There was no improvement in locomotor activity in all groups (p>0.05). Animals with CDMP that underwent RT showed an increase in hindlimb muscle strength (p<0.0001) compared to the RT control group.
CONCLUSION:
Low-intensity resistance training resulted in antihyperalgesic effects and improved muscle strength in animals submitted to the CDMP model.
Keywords:
Exercise; Fibromyalgia; Neurosciences; Resistance training
HIGHLIGHTS
Strength training attenuates hyperalgesia in rats with chronic diffuse muscle pain.
Strength exercise induces increased strength in rats with chronic diffuse muscle pain.
Rats with chronic diffuse muscle pain do not improve locomotion after strength exercise.
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RT = Resistance Training; RTC = Resistance Training Control; AMITRIP = Amitriptyline; AMC = Amitriptyline Control; IND = induction; TTO = treatment; *p<0.05 difference between pre- and post-induction of all groups; **p<0.05 in relation to pre-treatment of TR group; ***p<0.05 in relation to pre-treatment of AMITRIP group; †p<0.05 difference between TR and CTR groups; ‡p<0.05 difference between AMITRIP and AMC group; #p<0.05 difference between TR and AMITRIP group. Data are presented as mean ± standard error of the mean. RT, TRC, AMITRIP AMC at pre-induction (before the first acid saline injection), pro-induction (after DCMD induction), pre-treatment, every week of treatment and post-treatment. At pre- and post-induction (independent samples t-test) and pre-treatment, weeks and post-treatment (two-way ANOVA for repeated measures, followed by Tukey’s post hoc).
RT = Resistance Training; RTC = Resistance Training Control; AMITRIP = Amitriptyline; AMC = Amitriptyline Control; IND = induction; TTO = treatment; *p<0.0001 difference between pre- and post-induction. Data are presented as mean ± standard error of the mean. RT, TRC, AMITRIP AMC at pre-induction (before the first acid saline injection), pro-induction (after DCMD induction), pre-treatment, every week of treatment and post-treatment. At pre- and post-induction (independent samples t-test) and pre-treatment, weeks and post-treatment (two-way ANOVA for repeated measures, followed by Tukey’s post hoc).
RT = Resistance Training; RTC = Resistance Training Control; AMITRIP = Amitriptyline; AMC = Amitriptyline Control; IND = induction; TTO = treatment; *p<0.0001 difference between pre- and post-induction; *p<0.05 difference between TR and CTR groups, †p<0.05 in relation to pre-treatment in the TR group, ‡p<0.05 in relation to during in the TR group. Data are presented as mean ± standard error of the mean. Data are presented as mean ± standard error of the mean. RT and CTR at pre-treatment (after DCMD induction), during treatment (two weeks after starting treatment-D21) and post-treatment (after long-term treatment). One-way ANOVA for intra-group analysis and independent samples t-test to evaluate between groups.