Subjects

This study enrolled outpatients with CFS who visited the Department of Psychosomatic Medicine of Kyushu University Hospital. Inclusion criteria were the following: (1) the subject’s fatigue did not improve sufficiently with ordinary treatment given in our Department (as an example see [10]), including pharmacotherapy (for example, antidepressants, Japanese traditional herbal medicine [11],[12], and/or coenzyme Q10), psychotherapy, and/or GET; in some cases, a four-week inpatient treatment program was also included [10]) for at least six months; (2) the subject was between 20 and 70 years old; (3) the subject’s level of fatigue was serious enough to cause an absence from school or the workplace at least several days a month but not serious enough to require assistance with the activities of daily living; (4) the subject was able to fill out the questionnaire without assistance; (5) the subject could sit for at least 30 minutes; and (6) the subject could visit Kyushu University Hospital regularly every two or three weeks. Subjects were excluded if (1) their fatigue was due to a physical disease such as liver, kidney, heart, respiratory, endocrine, autoimmune, or malignant disease, severe anemia, electrolyte abnormalities, obesity, or pregnancy; and (2) they had previously practiced yoga. The diagnosis of CFS was made for patients meeting the diagnostic criteria of the 1994 international research case definition of CFS [1]. Patients with idiopathic chronic fatigue were not included in this study.

Methods

Following enrollment, eligible participants were randomized using a computer-generated randomization list to receive either an isometric yoga practice together with conventional pharmacotherapy group (yoga group, n = 15) or to a conventional pharmacotherapy alone group (wait-list control group, n = 15) for approximately two months. As the patients visited the hospital every two or three weeks, the intervention period lasted 9.2 ± 2.5 (mean ± standard deviation (SD)) weeks after the start of the intervention (Figure 1).

Development of the yoga program

Before starting this trial, we consulted yoga instructors to identify a program that would satisfy the following requirements. Firstly, because patients with CFS have severe fatigue, it should not exacerbate their symptoms or cause post-exertion malaise. Secondly, because the patients are deconditioned, it should also act as an exercise therapy. Thirdly, because the patients’ concentration and short-term memory are impaired, it should be simple and easy to do. Fourthly, because the patients would be treated at the hospital, not at a yoga studio, it must be able to be practiced in an outpatient setting, where space is limited. To satisfy these requirements, we determined that the trial would include isometric yoga, or an isometric yogic breathing exercise, as a treatment for patients with CFS. Isometric yoga, which was developed by Dr. Keishin Kimura, differs from traditional yoga postures in several ways. The predominant difference is that the poses consist mainly of isometric muscle contractions. Since the patients can change resistance depending on their fatigue level, we thought that isometric yoga would help prevent worsened fatigue. These poses do not include isotonic muscular contractions or strong stretching and require less physical flexibility. Therefore, we hypothesized that practicing this form of yoga would be easy on the patients, preventing over-stretching, which is detrimental and may increase pain. However, as are traditional yoga poses, these poses are conducted slowly in accordance with breathing and with awareness of inner sensations. We intentionally avoided standing postures, because a considerable number of CFS patients suffer from orthostatic intolerance, including postural orthostatic tachycardia syndrome [13]. This 20-minute yoga program can be practiced in a sitting position and consists of three parts. First, patients are asked to be aware of their spontaneous breathing for one minute. Next, they practice six poses. These poses are very slow movements that are coordinated with the timing of breathing, with or without sounds, and isometric exercise at 50% of the patient’s maximal physical strength. Lastly, the patients practice abdominal breathing for one minute (Figure 2).

Yoga intervention

Patients in the yoga group practiced isometric yoga in a quiet room for 20 minutes on a one-to-one basis with an instructor who has over 30 years of experience. The sessions occurred between 2 pm and 4 pm on the day they visited the hospital. In this program, the yoga instructor was not allowed to use background music, which is often used in the yoga studio to facilitate the participants’ relaxation, because many patients with CFS are sensitive to sounds. Before and after practicing isometric yoga, the doctors in charge checked the patient’s condition and recorded any adverse events or any changes caused by practicing isometric yoga. In addition to receiving a private lesson, the participants were asked to practice this program on non-class days if they could, with the aid of a digital videodisc and a booklet. Most patients visited their doctor every two to three weeks during the intervention period. Therefore, all patients practiced isometric yoga at least four times (mean ± SD, 5.6 ± 1.7 times) with the instructor during the intervention period. Basically, all patients practiced the same 20-min program, both with an instructor and at home. However, the program was modified on a patient-to-patient basis, in most cases skipping a certain pose or decreasing the number of repetitions of poses, depending on the severity of their fatigue and the pain associated with the pose.

Outcome assessment

To assess the acute effects of isometric yoga, the fatigue (F) and vigor (V) scores of the Profile of Mood States (POMS) questionnaire [14] were assessed immediately before and after the final 20-minute session of isometric yoga with the instructor. To assess the chronic effects of isometric yoga, fatigue was assessed with Chalder’s fatigue scale (FS) [15] before and after the intervention period in the yoga and control groups. Chalder’s FS is a well-validated, self-reported scale that measures the physical and mental symptoms of fatigue. In the yoga group, the assessments were conducted just before practicing yoga. Patients in this group also completed the Medical Outcomes Study Short Form 8, standard version (SF-8™) before and after the intervention period to assess their health-related quality of life (QOL) [16]. Questionnaires were collected by a nurse.

Adverse events and adherence

Adverse events were monitored in two ways. First, at each visit to the hospital, the doctors in charge determined if a subject experienced any uncomfortable symptoms after practicing yoga with the instructor. Second, patients in the yoga group were asked to keep a “yoga diary,” in which they could record the amount of time they practiced and how they felt after practicing yoga. On the day of the visit, before the patient practiced yoga with the instructor, the doctors checked the diary and determined if the patient had had any symptoms of discomfort. After the intervention period, the diary was collected and checked to determine how often the subjects had practiced yoga at home.

Statistical analyses

The data are presented as the mean ± SD. The differences in the outcome measures were tested by two-way, repeated measures, analysis of variance (ANOVA) of the mean scores. Two comparisons were made: one compared the scores of the yoga group to those of the control group; the other compared the scores measured before the intervention to those measured after. The differences in the patients’ POMS, Chalder’s FS, and SF-8 scores measured before and after the intervention were tested by use of a paired-sample t test. Between-group differences in age and in the POMS, Chalder’s FS, and SF-8 scores measured before and after the intervention were tested by use of an independent-sample t test. Two-tailed tests were used. Fisher’s exact probability test was also used when appropriate. Data were analyzed by using SPSS for Windows, V.17.

Participants

Short-term effects of isometric yoga on fatigue and vigor

We assessed the short-term effects of isometric yoga on fatigue by comparing the POMS F and V scores before and after the patients completed the final 20-minute session of isometric yoga with the instructor. We used the POMS because the Chalder’s FS is not appropriate for evaluating short-term changes in fatigue. Practicing isometric yoga significantly decreased the mean F score (from 21.9 ± 7.7 to 13.8 ± 6.7, P < 0.001) and increased the mean V score (from 17.8 ± 7.6 to 22.9 ± 8.2, P = 0.002) (Figure 3).

Long-term effects of isometric yoga on fatigue

To assess the long-term effects of regular practice of isometric yoga on fatigue, we compared the Chalder’s FS total score and the subscale scores for physical and mental symptoms of the control group to those of the yoga group before and approximately two months after the intervention. At baseline, the three scores did not differ significantly between the two groups.

We observed a significant main effect of time in the repeated measure ANOVA for the total score and for the two subscores (total score; f(1) = 12.4, P = 0.001: physical symptoms subscore; f(1) = 11.0, P = 0.002: and mental symptoms subscore; f(1) = 8.6, P = 0.007). We also found a significant interaction between the intervention and time (total score; f(1) = 10.2, P = 0.003: physical symptoms subscore; f(1) = 7.9, P = 0.009: and mental symptoms subscore; f(1) = 8.6, P = 0.007) (Figure 4 and Table 2). This finding indicates that patients who practiced yoga experienced a greater improvement in fatigue than did those who did not. The main effect for group was not significant for any score (total score; f(1) = 2.5, P = 0.124: physical symptoms subscore; f(1) = 2.9, P = 0.099: and mental symptoms subscore: f(1) = 1.4, P = 0.252).

At the time of the post-intervention evaluation, both the physical symptoms subscale score and the total score of the yoga group were significantly lower than those of the control group (P = 0.005, P = 0.022, respectively by the independent-sample t test). In the control group, neither the total score nor the two subscores differed significantly between the pre- and post-intervention evaluations. In contrast, in the yoga group the mean physical and mental symptoms subscores and the mean FS total score decreased significantly after the intervention period (P = 0.004, P = 0.004, P = 0.002, respectively, by the paired-sample t test; Figure 4).

Effect of regular practice of isometric yoga on health-related QOL

Safety and adverse events

At the hospital, one female subject complained of dizziness after her first yoga session. However, she did not require any specific treatment and she did not experience any negative symptoms in the subsequent sessions. After the first yoga session, two patients reported that they felt tired because they had to concentrate and follow the instructions. In subsequent sessions, neither reported that they experienced this symptom. None of the other patients reported any adverse symptoms. During the home practice, two patients reported that they felt light-headed when they practiced yoga with their eyes closed or on bad days, but not with their eyes open or on good days. Finally, none of the patients reported disabling post-exertion malaise after they practiced yoga.

Other patient reported outcomes

The short-term effects commonly reported by the patients after practicing isometric yoga included a feeling of warmth (n = 11) and lightness (n = 8). One subject mentioned that these benefits lasted for one hour. Seven patients reported that they felt more calm, relaxed, and worry-free. Five patients reported pain relief during their yoga practice. Two patients who have fibromyalgia syndrome as well as CFS skipped the arm-stretching pose because it was difficult and painful for them. They reported that, in the beginning, practicing yoga caused a transient increase in pain because they had to focus on the inner sensations of their bodies. However, as their practice proceeded, they were able to become detached from the pain, and they noticed that the severity of the pain decreased during a yoga session. Regarding the long-term effects, seven patients reported that they now noticed how tense they were in their daily lives and how helpful it was to release muscular tension during yoga. Two patients reported “After regular practice of yoga, I started to wake up more easily in the morning, which had been hard, because tiredness in the morning decreased.”

Adherence

Adherence was very good overall. All patients practiced yoga with an instructor when they visited the hospital. Fourteen of the 15 patients kept yoga diaries. Based on the records in their diaries, these 14 patients practiced isometric yoga at home for a mean of 5.8 ± 1.8 days/week and 5.7 ± 1.8 days/week during the first and last weeks of the intervention period, respectively.

Satisfaction

Fourteen of the 15 patients cited high satisfaction and described isometric yoga as being useful and helpful. One subject reported that she did not want to continue her yoga practice after the intervention period because she was afraid to close her eyes and to see inside.

Limitations

This study had several limitations. Firstly, the effects of yoga were evaluated for patients (1) whose fatigue level was not serious enough to require assistance with the activities of daily living, and (2) whose fatigue did not recover fully with ordinary treatment for more than six months. Secondly, we customized the yoga program for the patients in this study. Therefore, further studies are necessary to determine if we can generalize these findings to all patients with CFS or to any kind of yoga program. Thirdly, as this study evaluated the feasibility of a yoga program, we assessed the effects of isometric yoga for a relatively small number of patients and for a short intervention period. Two months might not be sufficient to fully evaluate the feasibility and the effects of yoga. Future studies should evaluate the long-term effects of isometric yoga. Finally, one subject did not want to continue practicing isometric yoga after the intervention period. This patient experienced psychological trauma at a young age and had a difficult life after that. Therefore, future studies should evaluate and treat comorbid psychiatric diseases, especially posttraumatic stress disorder, before considering treatment with yoga.