What muscles does vitamin D deficiency affect?

November 26, 2025 •

4 min read

According to numerous studies, vitamin D deficiency is linked to reduced muscle size and strength, especially in the legs and hips. The effects of low vitamin D can range from mild aches to significant weakness, impacting a person's ability to walk and balance. This guide explains what muscles does vitamin D deficiency affect and the underlying biological mechanisms.

Quick Summary

Vitamin D deficiency predominantly impacts skeletal muscles, particularly the large extensor and flexor groups of the lower limbs and the paraspinal muscles. This leads to weakness, pain, and atrophy due to impaired calcium regulation, mitochondrial function, and muscle fiber repair.

Key Points

Proximal Myopathy: Vitamin D deficiency specifically affects the proximal muscles of the hips, thighs, and pelvis, leading to weakness and difficulty with mobility.
Lower Limb Weakness: The large extensor and flexor muscles of the legs are significantly impacted, increasing the risk of falls and gait problems.
Paraspinal Muscle Atrophy: The muscles supporting the spine can atrophy due to low vitamin D, causing or exacerbating chronic low back pain.
Type II Fiber Damage: Fast-twitch (Type II) muscle fibers, responsible for powerful movements, are preferentially damaged and atrophied, reducing overall muscle strength.
Impaired Calcium Regulation: Low vitamin D disrupts the intracellular calcium balance essential for proper muscle contraction, leading to inefficient muscle function.
Mitochondrial Dysfunction: Vitamin D deficiency impairs mitochondrial activity, reducing energy (ATP) production and causing muscle fatigue.
Weakened Muscle Repair: The regenerative capacity of muscle fibers is compromised, slowing down healing and contributing to ongoing muscle problems.

Introduction to Vitamin D and Muscle Function

Vitamin D is a crucial steroid hormone that regulates calcium and phosphate homeostasis, which are essential for maintaining strong bones. However, its role extends far beyond bone health to directly influence skeletal muscle function, structure, and development. The widespread presence of vitamin D receptors (VDR) within skeletal muscle cells facilitates both rapid, non-genomic effects and longer-term genomic changes. When vitamin D levels are insufficient, these processes are disrupted, leading to a range of neuromuscular symptoms, most notably weakness and pain. This article delves into the specific muscle groups affected and the cellular mechanisms at play when the body lacks this vital nutrient.

Which Muscles are Most Affected?

While a vitamin D deficiency can cause widespread muscle issues, it has a particularly pronounced effect on certain muscle groups. The resulting condition, known as osteomalacic myopathy, involves muscle weakness, hypotonia (poor muscle tone), and pain.

Lower Limb Muscles

Research consistently shows that the large extensor and flexor muscles of the lower limbs are among the most severely impacted.

Proximal Muscles: This includes the muscles of the hips, thighs, and pelvis. Severe deficiency often results in proximal myopathy, characterized by muscle weakness in these areas. This can manifest as difficulty climbing stairs, rising from a chair or the floor, and a characteristic waddling gait.
Lower Leg Muscles: The muscles responsible for ankle dorsiflexion and knee extension are also negatively affected, contributing to mobility issues and a higher risk of falls, especially in older adults.

Axial Skeleton Muscles

Paraspinal Muscles: The muscles supporting the spine, known as the multifidus muscles, are susceptible to vitamin D deficiency. Studies have shown an association between low vitamin D levels and atrophy in these muscles, contributing to chronic low back pain.

Specific Muscle Fiber Types

Skeletal muscles are composed of different types of fibers, primarily slow-twitch (Type I) and fast-twitch (Type II). Vitamin D deficiency has a disproportionate effect on Type II fibers.

Type II Fiber Atrophy: Multiple studies indicate that low vitamin D status is associated with preferential atrophy of fast-twitch (Type II) muscle fibers. These fibers are responsible for explosive movements and generating power. Their degradation leads to reduced muscle strength and power, impairing physical performance.
Impact on Function: This selective atrophy explains the reduced grip strength and poor endurance observed in individuals with low vitamin D levels.

Cellular Mechanisms Behind Muscle Dysfunction

The link between low vitamin D and muscle weakness is rooted in several complex cellular processes. The vitamin's active form, 1,25-(OH)2D, interacts with vitamin D receptors (VDRs) found in muscle tissue to regulate these processes.

Disrupted Calcium Regulation: Vitamin D plays a key role in maintaining the balance of intracellular calcium, which is essential for proper muscle contraction. A deficiency impairs this calcium handling, directly affecting muscle performance and contractility.
Mitochondrial Dysfunction: Mitochondria are the powerhouses of muscle cells, producing the energy required for movement. Low vitamin D levels disrupt mitochondrial function, reducing the rate of oxygen consumption and ATP (energy) production. This metabolic impairment is a significant factor contributing to muscle fatigue and weakness.
Impaired Muscle Regeneration: Vitamin D is crucial for the repair and regeneration of muscle fibers. It enhances the differentiation of muscle stem cells (satellite cells) into mature myotubes, promoting muscle repair after injury or stress. A deficiency impedes this regenerative process, leading to a slower recovery and contributing to muscle atrophy over time.
Increased Oxidative Stress and Atrophy: Vitamin D deficiency is associated with higher levels of oxidative stress in skeletal muscle, which can damage cells and trigger catabolic pathways that promote muscle atrophy. The signaling pathways that regulate protein degradation become overactive, leading to a net loss of muscle mass.

Comparison of Muscle States: Healthy vs. Deficient


Characteristic	Healthy Muscle Function	Muscle Function in Vitamin D Deficiency
Calcium Regulation	Efficient and balanced intracellular calcium fluxes are maintained, ensuring strong, coordinated contractions.	Impaired calcium handling leads to weaker and less efficient muscle contractions.
Mitochondrial Energy	Mitochondria produce ample ATP, ensuring high oxidative capacity and supporting endurance and strength.	Mitochondrial dysfunction reduces ATP production, causing muscle fatigue and poor exercise performance.
Fiber Type	A healthy balance of Type I and Type II fibers is maintained, supporting a wide range of movements.	Preferential atrophy of fast-twitch (Type II) fibers leads to a loss of power and grip strength.
Regeneration	Satellite cells are readily activated, enabling effective muscle repair and growth after exercise or injury.	Muscle repair is delayed or impaired due to reduced satellite cell differentiation and increased fibrosis.
Overall Symptoms	Robust muscle function, high energy levels, and minimal muscle pain or weakness.	Reports of fatigue, persistent muscle aches, weakness (especially proximal), cramps, and increased fall risk.

Conclusion

Vitamin D deficiency is not merely a bone issue but a significant contributor to widespread muscle problems. The condition, known as osteomalacic myopathy, particularly impacts the large skeletal muscles of the lower limbs and the paraspinal muscles of the back, leading to proximal weakness and chronic pain. At a cellular level, the deficiency impairs crucial processes like calcium regulation, mitochondrial energy production, and the regeneration of fast-twitch muscle fibers, causing fatigue, weakness, and atrophy. Given the high prevalence of vitamin D deficiency, especially among older adults, it is a key consideration for healthcare providers when diagnosing musculoskeletal issues. Timely and appropriate supplementation can effectively reverse these muscle symptoms, highlighting the importance of maintaining adequate vitamin D levels for overall neuromuscular health.

For a deeper understanding of the molecular effects of vitamin D on skeletal muscle, refer to research findings from the National Institutes of Health.

Frequently Asked Questions

Muscle weakness from a vitamin D deficiency is often felt in the large muscles of the hips and thighs, making it difficult to perform daily tasks like climbing stairs, getting up from a chair, or walking. It can also be accompanied by muscle aches and cramps.

Yes, vitamin D deficiency can cause widespread muscle aches and pain. The pain-sensing nerve cells (nociceptors) have vitamin D receptors, and a deficiency may alter pain signaling pathways, contributing to chronic pain throughout the body.

Yes, the muscle weakness and myopathy caused by vitamin D deficiency are typically treatable and reversible with appropriate vitamin D supplementation. Clinical improvement can often be seen after correcting the deficiency.

The muscles in the hips and thighs are large and particularly rely on proper calcium regulation and Type II fast-twitch muscle fibers, which are disproportionately affected by low vitamin D. This makes weakness in these proximal muscle groups a classic sign of the deficiency.

Yes, low vitamin D levels can lead to hypocalcemia (low blood calcium) in severe cases. This electrolyte imbalance can cause muscle spasms and cramps, which may be one of the first signs of deficiency.

Yes, the muscle weakness and myopathy associated with vitamin D deficiency can be misdiagnosed as other neuromuscular disorders. It is important for doctors to consider vitamin D testing in patients with unexplained muscle symptoms to avoid unnecessary and invasive investigations.

Vitamin D plays a role in the differentiation of muscle cells and the regeneration of muscle fibers. A deficiency can lead to atrophy, particularly of the fast-twitch (Type II) fibers, which are essential for strength and power.