Testing Muscle Quality with Bloodwork

Neuro Athletes,

The age-related decline in muscle mass and strength, commonly referred to as sarcopenia, holds serious implications for an individual's overall health, functionality, and quality of life (Johnston et al., 2022). Research shows that, on average, adults lose between 3-8% of their muscle mass per decade after turning 30, a rate that intensifies after reaching the age of 60 (Smith & Brown, 2021). The decline in muscle mass and strength not only contributes to increased frailty and decreased mobility, but it is also associated with higher rates of all-cause mortality (Newman et al., 2006).

The relationship between muscle health and cognitive function, particularly in the context of neurodegenerative diseases like Alzheimer's, is an emerging area of scientific interest. Studies have found that sarcopenia is significantly associated with cognitive impairment and a higher risk for developing Alzheimer's disease (Burns et al., 2010). The mechanisms underlying this relationship are not entirely understood but may involve the role of insulin-like growth factor 1 (IGF-1), a hormone that has trophic effects on both muscle and brain tissue (Carro et al., 2002). Moreover, physical activity, known to benefit muscle mass, has neuroprotective effects and is associated with a lower risk of cognitive decline (Ahlskog et al., 2011).

Plant-based diets, although lauded for their capacity to mitigate risk factors for chronic diseases such as cancer, diabetes, and cardiometabolic conditions (Williams et al., 2019), also raise critical questions about nutritional sufficiency—particularly concerning protein intake, an essential element for muscle maintenance and growth.

One of the most potent and scientifically intriguing biomarkers for assessing not only kidney function but also muscle quality is serum creatinine. In a muscle-centric perspective, lower levels of serum creatinine could signify decreased muscle mass and consequently, an increased risk for the adverse health outcomes associated with sarcopenia (Robinson et al., 2018).

What is Serum Creatinine?

Serum creatinine is a consistent byproduct of muscle metabolism and is filtered through the kidneys (Davis & Miller, 2020). Although frequently used as a marker for kidney function, it also serves as an indicator of lean body mass, muscle strength, and muscle quality (Robinson et al., 2018). A study comparing vegetarian and omnivorous populations found that vegetarians had significantly lower serum creatinine concentrations (Anderson et al., 2021).

This could be interpreted as evidence of reduced muscle mass or quality in vegetarians since creatinine directly results from muscle metabolism. Notably, the study also found that omnivores had higher protein intakes, lean body mass, and handgrip strength, all of which were positively correlated with serum creatinine levels (Lee et al., 2022).

Dietary protein is essential for muscle protein synthesis, affecting muscle quality and strength (Friedman & Jensen, 2019). Animal proteins generally have a higher biological value, providing all essential amino acids needed for human health, unlike most plant-based proteins (Hall et al., 2020).

Amino acids like leucine are particularly important for initiating muscle protein synthesis (Kim et al., 2017). The lower biological value of plant proteins may contribute to the observed differences in muscle quality and serum creatinine levels between vegetarians and omnivores (Gomez et al., 2018).

Go Beyond Generic Bloodwork

If you’ve been following me for a while, you’ve heard me talk a lot about the benefits of regular blood testing for health optimization, which is why I love InsideTracker. InsideTracker uses data from your blood, DNA, and fitness trackers to give you personalized and science-backed recommendations on how to feel your best.

They provide a clear action plan for your diet, supplements, workouts, and other lifestyle choices like ways to improve sleep and reduce stress. InsideTracker tests and provides optimal ranges for over 40 biomarkers like ApoB, magnesium, vitamin D, testosterone, cortisol, ferritin, and more.

If you’re ready to get a crystal clear picture of what’s going on inside your body, check out InsideTracker.

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For those focused on human performance optimization, monitoring serum creatinine levels can serve as a valuable biomarker for muscle health and quality (Smith et al., 2023). Abnormal levels may indicate issues ranging from nutritional deficiencies to potential chronic conditions like kidney dysfunction (Wong et al., 2020). Maintaining muscle quality is essential as we age, affecting not just mobility but also overall health and cognitive capabilities (Chen et al., 2019). Thus, serum creatinine offers an invaluable tool for assessing muscle quality and guiding dietary and lifestyle interventions aimed at improving the aging process.

To learn more about bloodwork and what happens behind the scenes of getting your blood done, check this episode out.