Fibromyalgia is a condition causing widespread pain and fatigue, and researchers have noticed that people with it often have low vitamin D levels. In this study, 84 women with fibromyalgia did either strength training or relaxation exercises for 15 weeks. Researchers found that women with fibromyalgia started with lower vitamin D than healthy women, but both exercise types helped increase their vitamin D levels. The study also looked at inflammation markers in the blood and found connections between vitamin D and inflammation that changed after exercise. Importantly, different people responded differently to the same exercise program, suggesting that personalized treatment plans might work better for fibromyalgia patients.
The Quick Take
- What they studied: Whether exercise could increase vitamin D levels in people with fibromyalgia and how vitamin D relates to inflammation in the body
- Who participated: 84 women with fibromyalgia (ages 20-65) and 36 healthy women of similar ages. The fibromyalgia patients were randomly assigned to either do strength training or relaxation therapy
- Key finding: Women with fibromyalgia had significantly lower vitamin D at the start (78.0 vs. 90.6 units), but both strength training and relaxation therapy increased their vitamin D levels after 15 weeks. Healthy women’s vitamin D didn’t change much during the study
- What it means for you: If you have fibromyalgia, exercise may help boost your vitamin D levels, which could be important for managing your condition. However, people respond differently to exercise, so what works best may vary from person to person. Talk to your doctor about whether vitamin D testing and exercise are right for you
The Research Details
This was a randomized controlled trial, which is considered one of the strongest types of research studies. Researchers took 84 women with fibromyalgia and randomly divided them into two groups: one group did resistance exercises (like weight training) for 15 weeks, while the other group did relaxation therapy. A separate group of 36 healthy women served as a comparison to see how fibromyalgia patients differed.
Before and after the 15-week program, all participants had blood tests to measure their vitamin D levels and inflammation markers (called cytokines). Researchers also tested how strong participants were and asked about their symptoms. This allowed them to see whether exercise changed vitamin D levels and whether those changes connected to changes in inflammation.
The study was part of a larger research project with multiple centers, which means the findings are based on data from different locations, making the results more reliable.
This research design is important because it allows researchers to see cause-and-effect relationships. By randomly assigning people to different groups and measuring them before and after, scientists can be more confident that the exercise actually caused the vitamin D changes, rather than other factors being responsible. Comparing fibromyalgia patients to healthy controls helps show what’s different about the condition
This study has several strengths: it used a randomized design (considered high quality), included a control group of healthy people for comparison, measured objective blood markers rather than just asking people how they felt, and involved multiple research centers. However, the study only included women, so results may not apply to men with fibromyalgia. The sample size of 84 is moderate, which is reasonable but not huge. The study was published in a peer-reviewed journal, meaning other experts reviewed it before publication
What the Results Show
At the beginning of the study, women with fibromyalgia had noticeably lower vitamin D levels compared to healthy women (78.0 versus 90.6 units, a difference that was statistically significant). This confirms what researchers suspected—that fibromyalgia is connected to vitamin D deficiency.
After 15 weeks of either strength training or relaxation therapy, vitamin D levels in the fibromyalgia group increased significantly. This was an important finding because it showed that both types of activity—not just intense exercise—could help raise vitamin D. The healthy control group’s vitamin D levels didn’t change much during the same period.
The study also measured inflammation markers in the blood (called cytokines). At the start, researchers found connections between certain cytokines and vitamin D levels in people with fibromyalgia. However, after the 15-week intervention, these connections were no longer present, suggesting that the exercise or relaxation therapy changed how inflammation and vitamin D related to each other.
One interesting discovery was that people responded differently to the same exercise program. Some people’s vitamin D increased a lot, while others had smaller increases. This suggests that a one-size-fits-all approach may not work best for everyone with fibromyalgia.
The study measured physical capacity and symptom changes, though the abstract doesn’t detail these results. The fact that both strength training and relaxation therapy increased vitamin D was somewhat surprising, as it suggests that the activity itself—or possibly being part of a structured program—may be what matters, rather than the specific type of exercise. The different responses between individuals highlight that fibromyalgia affects people differently and may require personalized treatment approaches
Previous research had suggested links between fibromyalgia, vitamin D deficiency, and chronic inflammation, but this study is among the first to examine how these three factors connect during an exercise intervention. The finding that vitamin D increases with activity aligns with general knowledge that exercise and sunlight exposure boost vitamin D, but showing this specifically in fibromyalgia patients adds important new information. The discovery that inflammation markers’ relationship to vitamin D changes after intervention is a novel finding that wasn’t previously well-documented
This study only included women, so we don’t know if the same results would occur in men with fibromyalgia. The study lasted only 15 weeks, so we don’t know if vitamin D levels stay elevated long-term or if benefits persist. The study didn’t measure sun exposure or vitamin D supplementation, which could affect results. The sample size of 84 is moderate—larger studies might reveal different patterns. We also don’t know if the vitamin D increase directly caused symptom improvement or if other factors were responsible. Finally, the study was published in 2026, so long-term follow-up data isn’t yet available
The Bottom Line
If you have fibromyalgia, ask your doctor about: (1) Testing your vitamin D levels, as deficiency appears common in this condition (moderate confidence); (2) Including regular physical activity in your treatment plan, as both strength training and gentler activities like relaxation exercises may help boost vitamin D (moderate confidence); (3) Working with your healthcare provider to develop a personalized exercise plan, since people respond differently to the same activities (moderate confidence). These recommendations should complement, not replace, your current fibromyalgia treatment
This research is most relevant to women with fibromyalgia who want to understand the connection between exercise, vitamin D, and their condition. It may also interest healthcare providers treating fibromyalgia patients. People without fibromyalgia can benefit from the general principle that activity helps maintain vitamin D, but the specific findings apply mainly to fibromyalgia. Men with fibromyalgia should note that this study only included women, so results may differ
Vitamin D levels increased after 15 weeks of activity, so you might expect to see changes in blood work within a few months of starting regular exercise. However, symptom improvement may take longer and varies between individuals. Don’t expect overnight results—consistent activity over weeks and months is needed. Talk to your doctor about realistic timelines for your specific situation
Want to Apply This Research?
- Track weekly exercise minutes (both strength training and relaxation activities) alongside any vitamin D test results from your doctor. Set a goal of 150 minutes of moderate activity per week and log which type of activity you did each day
- Start with 2-3 sessions per week of either strength training (using light weights or resistance bands) or structured relaxation activities (like guided relaxation or gentle yoga). Gradually increase to 150 minutes per week. Log your activity type, duration, and how you felt afterward to identify patterns in your personal response
- Have your doctor check vitamin D levels every 3-6 months while maintaining regular exercise. Track your fibromyalgia symptoms (pain level, fatigue, sleep quality) weekly in the app to see if they improve alongside vitamin D increases. Note which types of activity seem to help you most, since individual responses vary
This research suggests associations between exercise, vitamin D, and fibromyalgia management, but it is not medical advice. Vitamin D levels and fibromyalgia treatment should be managed under the care of a qualified healthcare provider. Before starting any new exercise program, especially if you have fibromyalgia, consult with your doctor to ensure it’s appropriate for your individual condition. This study involved only women, so results may not apply to men. The findings represent one study and should be considered alongside other medical evidence and your personal health situation. Do not use this information to replace professional medical diagnosis or treatment
This research translation is published by Gram Research, the science division of Gram, an AI-powered nutrition tracking app.