Fact: Muscle decline can begin as early as mid-30s

Muscle health is critical to metabolism, resilience, and ability to stay functional well into later life.

Muscle Mass Loss

Muscle Mass Loss

Starting around your mid-30s, you begin losing approx 0.5% of muscle tissue per year. By your 80s, you may have lost around 20% of the muscle mass you had at your peak. This gradual decline of muscle mass with age, known as sarcopenia, is visible but manageable with the right nutrition and resistance training.

Muscle Strength Loss

Muscle Strength Loss

Strength falls far faster than muscle mass — and it can start earlier than expected. Even as muscle size appears relatively preserved, the nervous system’s ability to activate muscle fibers deteriorates, and the quality of the muscle tissue changes. By your 80s, functional strength can be nearly half of what it was at 30.

The Dynapenia Gap

The Dynapenia Gap

The gap between these two curves is the core problem. Strength declines 2–5× faster than mass, meaning you can look the same in the mirror while becoming significantly weaker. This disconnect — called dynapenia — can be a strong predictor of falls & loss of independence. Addressing it requires more than building mass; it demands directly targeting strength and neuromuscular function.

Sources

References

  • Mitchell WK et al. Front Physiol. 2012;3:260.
  • Delmonico MJ et al. Am J Clin Nutr. 2009;90(6):1579–85.
  • Frontera WR et al. J Appl Physiol. 2000;88(4):1321–26.
  • Clark BC & Manini TM. J Gerontol A. 2008;63(8):829–34.

What's happening at the cellular level

With age, muscle cells begin to lose metabolic efficiency, quietly accelerating with every decade. Excessive stress and inflammation suppress protein synthesis while accelerating muscle fiber breakdown, allowing in more intramuscular fat.

  • muscular fiber
  • intramuscular fat
  • connective tissue
Skeletal muscle

Muscle Strength Starts in the Gut

Your gut isn't just a digestive organ. It's a communication hub — sending signals to all parts of your body, including your muscle. The gut-muscle connection is a newly defined biological pathway, mapped over the last two decades.

The gut influences your muscle in 2 ways:

The gut influences your muscle in 2 ways:

Sends the right signals

Microbes in your gut produce molecules that can travel through your bloodstream and interact with muscle pathways to help repair, recover, and adapt to movement. Some of these molecules also reach the mitochondria — the energy-producing structure inside muscle cells.

Controls systemic inflammation

A healthy gut barrier keeps inflammatory toxins contained, preventing them from leaking into circulation and triggering inflammation.

With age, the bacteria that produce muscle-supporting signals decline, and the molecules arrive in smaller numbers. When the gut barrier weakens, those fragments can leak into circulation and trigger chronic inflammation — which contributes to the acceleration of muscle breakdown and impairs the body's ability to build new muscle.

The Solution: Spindle Muscle+ powered by

Shop Muscle+

Spindle Muscle+ is the targeted intervention. Powered by a clinical dose of Akkermansia MYO™ it preserves muscle and increases strength.

Many live probiotic strains degrade on the shelf, struggle through stomach acid, and often break down before ever reaching the gut. Through a complex process of heat-treated pasteurization, Akkermansia MYO™ is optimized to deliver consistent performance from capsule to body. 

Spindle muscle+ supplement packaging on a bathroom counter with Muscle+ Akkermansia product.

How Akkermansia Works

How Akkermansia Works

The Clinical Evidence

We tested this formulation in adults 60%, predominantly women, for 12 weeks using the gold standard in clinical research: a randomized, double blind, placebo controlled human clinical trial. This rigorous study design approach reduces bias and provides a high level of scientific confidence in the results.

increase in hamstring strength

+10.4%

increase in hamstring strength*

increase in quadricep strength

+8.9%

increase in quadricep strength*

Increase in grip strength

+5.0%

Increase in grip strength*

Muscle Maintenance

+5.6%

increase in prealbumin levels – biomarker for muscle maintenance & repair*

Muscle Growth

-38%

decrease in myostatin levels – biomarker that limits muscle growth when elevated*

increase in hamstring strength

+10.4%

increase in hamstring strength*

increase in quadricep strength

+8.9%

increase in quadricep strength*

Increase in grip strength

+5.0%

Increase in grip strength*

Muscle Maintenance

+5.6%

increase in prealbumin levels – biomarker for muscle maintenance & repair*

Muscle Growth

-38%

decrease in myostatin levels – biomarker that limits muscle growth when elevated*

*Based on a 12-week placebo-controlled study of Akkermansia MYO™ in adults ages 60-80 (predominantly women). Individual results may vary. Third-party clinical study, data on file.

*Based on a 12-week placebo-controlled study of Akkermansia MYO™ in adults ages 60-80 (predominantly women). Individual results may vary. Third-party clinical study, data on file.

More research of

A foundational clinical study in adults, predominantly women 60+ evaluated Akkermansia MYO™ at a daily dose of 10 billion pasteurized cells over 12 weeks. The results helped lay the groundwork for other formulations, including higher-dose. Mechanistic evidence supports the hypothesis that increasing the amount of these beneficial cells may further enhance gut health as well as muscle strength and health to support overall wellness.

Kang et al., Nutrients, 2024.
Link to trial

An in vivo trial is any study done in a living organism, which can include both animals and humans.

Experimental model:

Jeong DY, Song DY, Kim BC. Effectiveness of Akkermansia muciniphila HB05P in improving muscle strength and mass in the dexamethasone-induced skeletal muscle atrophy rat model. Korean Journal of Food Science and Technology. 2024;56(1):102–112. doi:10.9721/KJFST.2024.56.1.102. 

Measured Outcomes:

  • Restoration of DEX-reduced lean mass and reduction of body fat percentage and insulin levels → improved body composition via attenuation of insulin resistance
  • Increased endurance time, locomotor activity, and grip strength → recovery of impaired muscle function
  • Attenuation of muscle mass loss and significant increase in muscle fiber cross-sectional area → improved muscle morphology
  • Suppression of DEX-induced inflammation
  • Consistent regulation of myogenesis- and atrophy-related genes and proteins
  • Increased Akt/mTOR/FOXO3a phosphorylation → coordinated activation of protein synthesis and inhibition of protein degradation

An in vitro trial is a study done outside a living body, like in a test tube or petri dish, to see how a treatment works on cells or tissues. It helps researchers understand basic effects before testing in living organisms.

Experimental model:

C2C12 skeletal muscle precursor cells (myoblasts) with dexamethasone-induced muscle atrophy

Measure Outcomes:

●     Protective effects on DEX-induced reductions in cell viability and myotube diameter

●     Decreased atrophy-related factors: Myostatin, MuRF-1, Atrogin-1

●     Increased myogenic factors: IGF-1, MyoD, Myogenin

●     Restoration of Akt/mTOR phosphorylation → enhanced protein synthesis

●     Increased FOXO3a phosphorylation → suppressed protein degradation

In pre-clinical studies, Akkermansia MYO (1) restored muscle cell viability and structural integrity, (2) helped regulate factors involved in muscle protein synthesis and degradation, and (3) supported normalized Akt/mTOR/FOXO3a signaling, thereby (4) improving systemic muscle function.

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REFERENCES

Kang et al., Nutrients, 2024. Based on a randomized, placebo-controlled 12-week study of Akkermansia MYO™ in adults ages 60+ (mostly women). Mechanism of action and basic science support broader expected benefits. Individual results may vary based on biology, lifestyle, and other individual factors. 

Third-party clinical study, data on file. Based on a randomized, placebo-controlled 12-week study of Akkermansia MYO™ in adults ages 60-80 (mostly women). Mechanism of action and basic science support broader expected benefits. Individual results may vary based on biology, lifestyle, and other individual factors. 

Depommier et al., Nature Medicine, 2019. Based on a 3-month clinical study of pasteurized Akkermansia in overweight or obese adults with insulin resistance and metabolic syndrome. Individual results may vary.