There were no differences between the resistance exercise programme and the pool exercise programme in fatigue; however, both groups appeared to improve in different dimensions of fatigue.

Chronic widespread pain (CWP) is a common condition in primary health care. CWP has been defined as the presence of pain in the right and left side of the body, above and below the waist combined with axial pain, lasting for at least three months. The prevalence of CWP in the general populations has been estimated to be between 3 % and 9 % among men and between 5 % and 16 % among women. Substantial fatigue is common among patients with CWP, and fatigue has been found to be associated with pain, psychological distress, limited physical performance and decreased working capacity in patients with chronic pain. Fatigue, pain and sleep disturbances in men with fibromyalgia (FM) tend to be higher than those in healthy controls but lower than those in women with FM. The symptoms associated with CWP and FM can be controlled to some degree with pharmacological and non-pharmacological treatments. Different types of exercise have been shown to have positive effects on several symptoms and the physical capacity of patients with FM. In addition, exercise is commonly known to enhance general health, which facilitates coping with pain, fatigue and other common symptoms of FM. However, patients with chronic pain associated with aberrations in the central pain mechanisms have shown a dysfunctional response to exercise in the form of increased general pain sensitivity. Patients with FM have also been found to lack pain inhibition during muscle contractions. Aerobic exercise, such as pool exercise or Nordic walking, has a positive impact on pain, global well-being and physical function in women with FM and CWP. Resistance exercise has been found to improve muscle strength, overall health and current pain intensity in a recent study of women with FM. Most studies with CWP concern female patients only or a mix where men are in the minority, and the knowledge regarding the effects of all types of exercise on men with CWP is insufficient, especially the impact of exercise on fatigue, which was the reason for initiating the present study.

Rationale behind research:

• There is very limited knowledge about the effects of exercise on men with Chronic Widespread Pain, especially regarding fatigue
• The present study was conducted so as to investigate the effects of resistance exercise compared with pool exercise on multidimensional fatigue, psychological distress and physical capacity in men with CWP

Objective

To compare the effects of resistance exercise and pool exercise in temperate water on multidimensional fatigue, symptoms of depression and anxiety, isometric force, pain and health-related quality of life in men with CWP.

Study outcomes

• Primary Outcomes: The primary outcome was fatigue, which was assessed in multiple dimensions with the Multidimensional Fatigue Inventory (MFI-20). The questionnaire assesses 5 subscales of fatigue: general fatigue, physical fatigue, mental fatigue, reduced motivation and reduced activity. The MFI-20 contains 20 statements that refer to aspects of fatigue experienced during the recent days. The sum score of each subscale ranges from 4 to 20 and a higher score indicates a higher degree of fatigue. The MFI-20 has shown satisfactory construct and content validity and test retest reliability for CWP. The MFI-20 has been shown to be sensitive to changes in previous exercise studies in populations with FM and CWP [27, 28, 40]; however, there is no established minimal clinically important difference for the instrument.
• Secondary Outcomes: The secondary outcomes were symptoms of anxiety and depression and isometric forces of shoulder abduction, knee extension, knee flexion and hand grip. The exploratory outcomes were pain intensity, the number of pain localisations and health-related quality of life.

Time Points: Baseline and after 12 weeks

Outcomes:

Baseline: There were no significant baseline differences between the two groups of exercise in socio-demographic data or outcome variables, except for SF-36 MCS (PE mean 46.0, SD 14.1 versus RE mean 35.6, SD 13.5; p = 0.029).

12-week examination: No significant differences were found for the changes in MFI-20 subscales at 12-week examination between pool exercise and resistance exercise group. The isometric forces of the right arm shoulder abduction and the knee flexion in both legs improved significantly in the resistance exercise group than the pool exercise group.

Within-group comparisons:

• Pool exercise group: MFI physical fatigue, MFI reduced motivation, HADS-A, the number of pain localisations and the SF-36 PCS improved significantly from baseline to the 12-week examination in the pool exercise group
• Resistance exercise group: MFI general fatigue, isometric forces of the right arm shoulder abduction and knee flexion and the number of pain localisations improved significantly from baseline to the 12-week examination in the resistance exercise group

Progress of exercise intensity:

• Pool exercise group: Patients’ RPE values were assessed in 4–5 patients in week 8 and week 11 to be able to illustrate the intensity of pool exercise programme. In week 8, the RPE values ranged from 8.5 to 12 (“very light” to “fairly light”) during flexibility and coordination exercises and from 13.5 to 16 (“somewhat hard” to “very hard”) during aerobic exercise. In week 11, patients’ RPE values ranged among patients from 10 to 15 (“fairly light” to “somewhat hard”) during flexibility and coordination exercises from 16 to 17 (“very hard”) during aerobic exercise.
• Resistance exercise group: The initial load at week one was 40–50% of one RM, with 3 sets of 15–20 repetitions. The mean increase in load from week 1 to week 12 was found to be between 37% and 53% of 1 RM for the different exercises.
  

The present study showed that both a 12-week supervised resistance exercise programme and a 12-week supervised pool exercise programme improved dimensions of fatigue in men with CWP. No difference was found for change in fatigue between the groups. MFI general fatigue decreased significantly over time within the resistance exercise group, and a tendency towards improvement in MFI general fatigue was found in the pool exercise group (p = 0.051). Physical fatigue and reduced motivation were significantly improved over time in the pool exercise group, which is in line with previous studies where the MFI-20 reduced motivation subscale has improved in groups engaging in aerobic exercise. The resistance exercise group improved in isometric forces of right arm shoulder abduction and knee flexion in both legs of men with CWP compared with the pool exercise group. The mean values of isometric force of the right arm shoulder abduction and knee flexion in both legs increased from baseline to post-test between 21 % and 34 % in the resistance exercise group. This result is similar to the expected improvement in resistance exercise in untrained and moderately trained healthy individuals; that is, an improvement in muscle strength of approximately 40 % and 20 %, respectively.

There is a scarcity of studies investigating the effects of treatments on men with CWP. Thus, there are no recommendations regarding choice of exercise for men with CWP, which was the reason for conducting the present pilot study. The results of the present study can be used for the determination of sample size in future studies of men with CWP.