If you are dealing with persistent aches, recovering from an injury, or trying to stay strong as you age, vitamin D might come up in conversation. Many people think of it as an “immune vitamin” or something related only to bone health. In reality, vitamin D plays a much bigger role in how your muscles, bones, and connective tissues function and recover.

As physical therapists, we are frequently asked whether vitamin D levels matter for pain, strength, and rehabilitation. The short answer is “yes.” The longer answer is worth unpacking.

Why Does Your Body Need Vitamin D?

Vitamin D is a fat–soluble vitamin that acts more like a hormone than a typical nutrient. Your body can make it when your skin is exposed to sunlight, and you can also get smaller amounts from food and supplements.

Once vitamin D is activated in the body, it helps regulate calcium and phosphorus levels. These minerals are essential for bone strength, muscle contraction, and nerve signaling. Vitamin D receptors are found in muscle tissue, bone, and many other organs, which explains why low levels can affect how your body feels and functions.

Vitamin D and Musculoskeletal Health

Bone Strength and Injury Risk

Vitamin D is critical for calcium absorption. Without enough vitamin D, your body cannot effectively use the calcium you consume, even if your diet is adequate. Low vitamin D levels are associated with:

• Lower bone mineral density
• Higher risk of stress fractures
• Increased fracture risk in older adults

For patients undergoing physical therapy, especially those recovering from fractures or managing osteoporosis or osteopenia, vitamin D status can influence how well bones adapt to loading and heal over time.

Muscle Strength and Performance

Vitamin D also plays a direct role in muscle function, as research shows that a deficiency is associated with:

• Reduced muscle strength
• Slower muscle contraction
• Higher risk of falls, especially in older adults

Several studies have demonstrated that correcting low vitamin D levels increases lower–extremity strength and balance. This is particularly relevant for patients trying to improve their gait and stair climbing abilities while also reducing their risk for falls.

If you feel weaker than expected despite consistently engaging in therapy and exercise, your vitamin D status could be a contributing factor worth discussing with your healthcare provider.

Pain and Recovery

Low vitamin D levels have been linked to chronic musculoskeletal pain, including diffuse muscle aches and low back pain. While vitamin D is not a pain medication, correcting a deficiency may reduce your pain sensitivity and improve your tolerance to exercise. In rehabilitation, this could mean:

• Better participation in strengthening programs
• Improved recovery between sessions
• Fewer setbacks related to fatigue or soreness

The evidence in this specific area is mixed, but it leans toward showing a benefit for those with a true vitamin D deficiency.

Benefits Beyond the Musculoskeletal System

While the focus of this article is on movement and recovery, it’s important to note that vitamin D also supports:

• Immune system regulation
• Cardiovascular health
• Metabolic function
• Mood and cognitive health

These effects are still being studied, but they help explain why vitamin D deficiency has been associated with higher overall health risks, particularly in older adults and people with limited sun exposure.

Common Questions and Concerns About Vitamin D

How Do I Know If My Vitamin D Is Low?

Vitamin D status is measured with a blood test called 25–hydroxyvitamin D. In the U.S., general reference ranges are as follows:

• Deficient: below 20 ng/mL
• Insufficient: 20 to 29 ng/mL
• Sufficient: 30 to 50 ng/mL

Many experts agree that levels below 30 ng/mL are suboptimal for musculoskeletal health, particularly in people with pain, injuries, or fracture risk.

Can You Get Enough Vitamin D From Sunlight Alone?

Sometimes, but not reliably. Factors that reduce vitamin D production include:

• Living in northern latitudes
• Winter months
• Sunscreen use
• Darker skin pigmentation
• Spending most of the day indoors

Because of these variables, deficiency is common, even in otherwise healthy adults.

Is Too Much Vitamin D Dangerous?

Yes, but toxicity is rare and almost always due to excessive supplementation over time, not sun exposure. Very high vitamin D levels can lead to elevated calcium levels, which may cause kidney problems and other symptoms. This is why supplementation should stay within evidence–based ranges unless supervised by a physician.

How Much Vitamin D Do I Need?

For most adults, 800–2,000 IU per day is commonly recommended for vitamin D maintenance, but many people need 1,000–2,000 IU daily to maintain sufficient blood levels. If blood levels of vitamin D are low, healthcare providers may recommend up to 2,000–4,000 IU per day or short–term higher doses under medical supervision.

Follow–up blood testing is often used to ensure levels normalize without overshooting. Vitamin D is fat–soluble, so it absorbs best when taken with a meal that contains fat.

Consider Vitamin D Supplementation With Physical Therapy to Support Your Recovery

Vitamin D is not a cure–all, but it is a foundational factor in bone health, muscle strength, and recovery. The strongest evidence supports correcting deficiency to improve musculoskeletal outcomes, reduce fall risk, and support overall function.

Rehabilitation also works best when all the pieces are aligned. Exercise, movement quality, sleep, nutrition, and overall health all matter. So, if you are dealing with ongoing pain, weakness, or balance issues, our physical therapists can help you identify barriers to progress and build a plan that fits your goals. Contact our clinic today to schedule an appointment and take the next step toward moving better and feeling stronger.

References and Further Reading

1. NEJM.org
2. PubMed.NCBI.NLM.NIH.gov
3. Link.Springer.com
4. FrontiersIn.org
5. USPreventiveServicesTaskForce.org