Sexual dysfunction refers to difficulties that can occur at any stage of sexual activity, including desire, arousal, orgasm, and overall satisfaction. Among men, erectile dysfunction (ED) is one of the most widely studied forms.

ED is characterized as the persistent inability to achieve or maintain an erection sufficient for satisfactory intercourse.

The causes are multifactorial, spanning vascular, neurological, hormonal, and psychological factors. Vasculogenic ED, in particular, is closely linked to endothelial dysfunction, which is the impaired ability of blood vessels to dilate properly⁽¹⁾.

Emerging evidence suggests that a body composition favoring higher skeletal muscle mass relative to fat supports better metabolic health and reduces inflammation, both of which protect vascular function⁽²⁾. 

Conditions that promote atherosclerosis, such as aging and low muscularity, are also associated with endothelial dysfunction and ED⁽¹⁾.

Frailty and sarcopenia, while related, describe distinct age-related syndromes. Frailty involves a general decline in strength, resilience, and physiological reserves across multiple systems. Sarcopenia refers specifically to the loss of muscle mass, muscle strength, and/or physical performance⁽¹⁾. 

Because direct measurement of skeletal muscle (via MRI or CT) is not common in clinical practice, muscle health is often estimated indirectly through measures such as fat mass or strength testing.

Research shows that severe ED is significantly more common in men with sarcopenia⁽⁴⁾. 

In older adults, sexual dysfunction and muscle loss often occur together, reflecting the metabolic and endocrine roles of skeletal muscle. Although most studies focus on older or hypogonadal men, the relationship between muscle mass and sexual health may also be relevant for younger men with subtle or early declines in muscle quality⁽³⁾.

Testosterone is a key regulator of both muscle growth and sexual function. While its role in arousal, libido, and erectile capacity is well established, skeletal muscle itself may independently influence sexual health through its effects on metabolism, vascular function, and inflammation⁽⁴⁾. 

Understanding this connection could expand therapeutic strategies beyond hormone replacement alone.

Physiological Connections

Erectile function depends on the coordinated dilation of penile blood vessels. Sexual stimulation activates parasympathetic nerves that release nitric oxide (NO) and acetylcholine, triggering a cascade that increases cyclic GMP, relaxes smooth muscle, and allows blood to fill the erectile tissue. The tunica albuginea then traps this blood, maintaining rigidity⁽⁵⁾. 

Endothelial dysfunction disrupts this process, often through oxidative stress, insulin resistance, and chronic inflammation.

Skeletal muscle plays a central role in glucose regulation. It accounts for about 40% of body weight in a healthy adult and is the primary site for post-meal glucose disposal via insulin-sensitive GLUT-4 transporters. This helps maintain normal blood sugar and improves insulin sensitivity which are both essential for vascular and erectile health. Chronic hyperglycemia and insulin resistance impair NO production, directly contributing to ED⁽⁶⁾.

Muscle tissue also regulates lipid metabolism, acting as a major site for fatty acid oxidation. Efficient lipid handling reduces triglyceride levels, improves HDL cholesterol, and protects endothelial health. Conversely, high body fat and low muscle mass promote inflammatory cytokine release, worsen insulin resistance, and suppress testosterone production, creating a self-reinforcing cycle of metabolic and sexual decline⁽⁷⁾.

Exercise and Hormonal Effects

Resistance training and regular physical activity help preserve muscle mass, reduce oxidative stress, and support mitochondrial health, factors that protect both vascular and sexual function. Exercise can also boost testosterone levels and increase androgen receptor expression in muscle, enhancing the hormonal environment for growth and performance. Stronger pelvic floor muscles, supported by overall muscular strength, contribute directly to erectile rigidity⁽⁵⁾.

Population Findings

General adult populations


Studies in Nordic–Baltic and Japanese men show that greater muscle strength is associated with better erectile function, sexual desire, and performance even after adjusting for testosterone levels.

Although BMI is a limited measure of body composition, higher BMI, by contrast still correlates with worse outcomes.

Older adults


In community-dwelling older men, lower muscle mass and strength consistently predict higher ED prevalence. Some studies find that participation in muscle-strengthening activities reduces ED risk, suggesting that maintaining muscle is particularly important in later life⁽⁸⁾.

Men with chronic conditions


Diabetes, metabolic syndrome, rheumatoid arthritis, kidney disease, and post-prostatectomy states all show evidence of reduced sexual function linked to lower muscle mass or strength. In these populations, inflammation, hormonal changes, and vascular compromise interact with muscle loss to worsen sexual outcomes⁽⁶⁾.

Testosterone: Central but Not the Whole Story

Testosterone drives muscle growth through multiple pathways, including:

• Binding androgen receptors in muscle cells to promote protein synthesis
• Activating satellite cells for repair
• Stimulating growth hormone and IGF-1 release

Higher testosterone levels correlate with greater muscle mass and strength in adolescents, adults, and older men.

It also supports endothelial health, enhancing NO production, reducing inflammation, and promoting new blood vessel formation. Low testosterone is both a cause and a consequence of poor vascular and muscular health.

While testosterone therapy benefits hypogonadal men, improving muscle mass, physical function, libido, and erectile capacity, and muscle health itself can influence sexual function independently.

This suggests that treatment strategies should address both hormonal and muscular factors.

Clinical Implications

Evidence supports the use of simple, non-invasive muscle assessments such as hand-grip strength or bioelectrical impedance to help identify men at risk for sexual dysfunction. Because muscle quality is modifiable, interventions like resistance training, adequate protein intake, and targeted supplementation may complement standard ED therapies.

Potential adjuncts under study include:

• Clomiphene citrate, which can raise testosterone and increase muscle mass, though evidence for direct sexual function benefits is limited.
• L-carnitine, which supports muscle metabolism and endothelial health in preclinical models.
• Vitamin D, which influences muscle and vascular function, particularly in deficient individuals.

Future research should include more diverse populations, longitudinal designs, and integrated measures of muscle, hormonal, and vascular health. 

Skeletal muscle health, both in mass and strength, emerges as an underrecognized determinant of male sexual function, operating alongside but also independently of testosterone. The interplay among muscle, metabolism, vascular health, and hormones suggests that preserving muscle may be as important for sexual well-being as it is for mobility and overall health.

For now, the evidence points to a straightforward clinical message, which is building and maintaining muscle helps you stay strong and also helps sustain a healthy and fulfilling sex life.

Healthy skeletal muscle serves as your body's metabolic powerhouse, regulating blood flow, hormone sensitivity, and cellular energy production, which are all critical factors in sexual health and overall vitality. 

Protein is the non-negotiable building block of this equation.

Your muscles require a consistent supply of complete amino acids to maintain mass and sustain the metabolic processes that support peak performance. Without adequate protein intake, muscle protein synthesis drops, leading to gradual loss of the very tissue that underpins your vitality.

STEEL has an entire line of delicious proteins that contain all the essential amino acids you need to fuel your life!

References:
    1.    Viken AF, Siiak SP, Schlünssen V, et al: Muscle Strength and Male Sexual Function. J Clin Med 13, 2024
    2.    Corona G, Rastrelli G, Morelli A, et al: Treatment of Functional Hypogonadism Besides Pharmacological Substitution. World J Mens Health 38:256-270, 2020
    3.    Cesari M, Landi F, Vellas B, et al: Sarcopenia and physical frailty: two sides of the same coin. Front Aging Neurosci 6:192, 2014
    4.    Park H, Jang IY, Han M, et al: Sarcopenia is associated with severe erectile dysfunction in older adults: a population-based cohort study. Korean J Intern Med 35:1245-1253, 2020
    5.    Levine AB, Punihaole D, Levine TB: Characterization of the role of nitric oxide and its clinical applications. Cardiology 122:55-68, 2012
    6.    Chen LY, Xia MF, Wu L, et al: Skeletal muscle loss is associated with diabetes in middle-aged and older Chinese men without non-alcoholic fatty liver disease. World J Diabetes 12:2119-2129, 2021
    7.    Hauck AK, Bernlohr DA: Oxidative stress and lipotoxicity. J Lipid Res 57:1976-1986, 2016
    8.    Zhou H, Xu M, Xu Z, et al: The association of various physical activities with erectile dysfunction: NHANES 2001-2004. Sexual Medicine 11:qfad036, 2023