Lactate & Cancer: A Double-Edged Sword
The latest wave of cancer research, especially papers emerging from 2024 onward, has transformed our understanding of lactate. Once dismissed as a mere waste product of exertion, lactate is now seen as a powerful metabolic signal — one that can either help cancer escape immune detection or help the body find and destroy cancer, depending on the context in which it’s produced.
This singular understanding has immense significance for cancer treatment, care, and prevention. It reframes lactate not as an inert byproduct but as a double-edged molecule whose effects depend entirely on where, when, and how it is produced.
This paradox lies at the heart of a crucial insight: lactate is not inherently good or bad — it’s context that determines its role.
A 2025 paper, Context Matters: Divergent Roles of Exercise-Induced and Tumor-Derived Lactate in Cancer, put it clearly:
In other words, the right kind of high-intensity exercise may switch the immune system on—directly supporting the body’s fight against cancer.
Tumour-Derived Lactate: Fuel for Immune Evasion
Cancer cells are notoriously adaptable. Within tumours, cancer cells ramp up their glucose consumption and convert much of it to lactate even when oxygen is available — a phenomenon known as the Warburg effect. This creates a tumour microenvironment saturated with lactate and acidic hydrogen ions.
Far from being harmless, this acidic lactate bath becomes a weaponised shield. It:
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Expands regulatory T cells (Tregs), which normally prevent autoimmunity but here are co-opted to suppress anti-cancer immune responses.
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Disables cytotoxic T cells and natural killer (NK) cells, the immune system’s primary cancer hunters.
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Reprograms surrounding cells to support tumour growth and spread rather than resist it.
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Drives epigenetic changes that make cancer cells more aggressive and resistant to therapy.
In short, tumour-produced lactate becomes a cloak of invisibility, silencing immune alarms and allowing cancer to grow unchecked.
Exercise-Derived Lactate: Fuel for Immune Activation
By contrast, when lactate is produced by active muscles during intense exercise, it enters the bloodstream in a clean, oxygen-rich environment and behaves entirely differently. Instead of suppressing immunity, exercise-derived lactate stimulates it.
Circulating lactate from muscle:
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Energises cytotoxic T cells and NK cells, helping them find and kill cancerous cells.
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Activates myokines — muscle-derived signalling proteins that dampen inflammation and trigger systemic repair.
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Boosts mitochondrial renewal and blood vessel growth, strengthening organs and tissues against future disease.
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Acts as a signalling molecule, alerting immune cells and mobilising them to survey tissues for threats.
Even more striking, lactate helps reverse the immune paralysis seen in cancer by shifting the body back toward an anti-tumour state. Where tumour-derived lactate hides cancer, muscle-derived lactate helps expose it.
Why Context Matters
This duality explains why exercise is consistently linked with lower cancer risk and improved survival — but also why the wrong kind of exercise can be counterproductive.
If exercise is too mild, it fails to produce enough lactate to stimulate immunity. If it is too prolonged and exhausting without recovery, it can mimic the metabolic stress that cancer exploits, worsening inflammation and immune dysfunction.
Targeted, high-quality resistance training — such as with KineDek AI-CRT — rapidly drives lactate production and clearance in bursts, without causing systemic stress. This harnesses lactate’s immune-activating power while avoiding its tumour-like accumulation, creating an internal environment that is hostile to cancer rather than protective of it.
In short, tumour-produced lactate becomes a cloak of invisibility, silencing immune alarms and allowing cancer to grow unchecked.
Yet the story does not end there. Emerging evidence suggests that lactate balance — and therefore immune balance — can be restored through lifestyle changes. Increased physical activity, targeted resistance training, improved diet, and other metabolic interventions all help shift the body’s lactate signalling away from tumour-like accumulation and toward exercise-like bursts. This rebalancing may in large part explain why many patients, even those with advanced disease, have reported periods of complete remission following sustained lifestyle change.
Turning Lactate Into an Ally
Lactate is not the enemy. It is the derivative of lactic acid once its acidic hydrogen ions dissociate (Lactic acid ⇌ Lactate⁻ + H⁺ ≡ C₃H₆O₃ ⇌ C₃H₅O₃⁻ + H⁺) — and those ions, not lactate itself, are what cause the sharp burn during effort. Lactate itself is a vital superfuel for the heart, brain, and immune system.
When produced by healthy muscle metabolism, it becomes a signal of vitality, not disease — a molecular spark that ignites immune surveillance, tissue regeneration, and metabolic resilience.
In cancer, the difference between harm and healing is not lactate’s presence, but its context. Tumours use lactate to hide. Muscles use it to fight. And understanding that difference could reshape how we approach cancer prevention, recovery, and care.
Case Example: Reduction of LDH Levels
The KineDek AI-CRT produces an intense lactate response, evident in the unique muscular sensation it creates—unlike that from any other activity. Remarkably, this is followed by rapid clearance, with no lingering pain or stiffness, and muscles feel more energized rather than fatigued.
A striking case demonstrating its potential impact on the tumour environment is that of Costa, a 70-year-old man who, in June 2024, was told that chemotherapy was not viable due to critically high Lactate Dehydrogenase (LDH) levels—a marker associated with both tumour progression and muscle decay. At that point, his prognosis was limited to weeks, if not days.
After beginning twice-weekly light KineDek sessions into the burn zone, Costa’s LDH levels showed a marked reversal within three weeks. This shift allowed oncologists to proceed with chemotherapy, and he remains alive today.
For more on Costa’s case, go to this link.
Order of Lactate-Producing Muscles by Dominance
Leg muscles (largest myokine producers):
Quadriceps (front of thigh)
Hamstrings (back of thigh)
Gluteals (buttocks)
Calves (gastrocnemius, soleus)
These drive the majority of systemic immune activation because of their size and high metabolic demand.
Core muscles (circulation, lymph, and inflammation control):
Abdominals (rectus abdominis, obliques, transverse abdominis)
Erector spinae (deep spinal muscles)
Strong core engagement improves circulation, lymphatic flow, and even prostate and gut health—key immune hubs.
Upper body power muscles (additional systemic support):
Pectorals (chest)
Latissimus dorsi (back)
Deltoids & biceps/triceps (shoulders and arms)
While smaller than the legs, engaging these adds to systemic lactate signaling and whole-body immune effects.
📌 Why it matters:
Activating large lower-body muscles produces the strongest lactate pulse, which fuels immune cells like NK cells and T cells.
Engaging the core boosts lymphatic and venous return, clearing inflammatory byproducts faster.
Adding upper-body power muscles spreads the metabolic and immune demand, amplifying the systemic response.
Rule of Thumb: Target Muscle Activation by Proximity and Systemic Impact:
The closer a muscle is to the area of cancer, the more beneficial its activation tends to be — because myokine action, which plays a central role in immune modulation and tumour suppression, occurs primarily in the region of the activated muscles.
Additional Note: Why Injecting Lactate Is Not the Same as Exercise
It may be tempting to think that if lactate is so beneficial, we could bypass exercise and simply inject it into the bloodstream. But this misses the point. Lactate’s power lies in the context of its release, not in its chemical identity alone.
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Lactate as a signal, not just a substance: During exercise, lactate is released alongside a burst of myokines that occur only with relatively intense muscle contraction — especially IL-6. Here lies the IL-6 paradox: chronically elevated IL-6 in conditions like obesity or cancer drives inflammation and tumour escape, yet exercise-induced IL-6 is anti-inflammatory — triggering IL-10 and IL-1Ra, mobilising natural killer cells, and sharpening immune surveillance. Injected lactate lacks this companion signalling, and so the immune system does not interpret it in the same way.
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Clearance and rhythm matter: In exercise, lactate rises in pulses and is rapidly cleared by muscle, heart, liver, and kidneys. This cyclical rise-and-clearance is part of the training effect. An injection, by contrast, produces a static spike with none of the adaptive rhythm.
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Hydrogen ion handling: During exercise, lactate production is coupled with buffering systems, oxygen delivery, and mitochondrial utilisation, preventing harmful acidosis. Injected lactate, while not itself acidic, bypasses these natural safeguards and lacks the coordinated physiological response that accompanies exercise-derived lactate.
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Immune positioning: Muscle contractions mobilise blood and lymph, ensuring that immune cells are exposed to lactate and myokines in the right place and time. No injection can replicate this choreography.
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Adaptation requires stress–recovery, not shortcut: The benefits of lactate are inseparable from the adaptive stress of exercise itself. Without the upstream contraction, mechanical load, and recovery, lactate is just an inert metabolite — as it is in the tumour environment.
Additional Note: The Problem With Conventional Exercise
Exercise has been definitively shown to:
Act as a powerful cancer deterrent, lowering risk across multiple cancer types.
Directly fight cancer, in part by mobilising the immune system against tumour cells.
Serve as the most important intervention supporting patients during and after treatment, improving recovery and survival.
The dilemma lies in the intensity threshold. For exercise to generate a lactate response strong enough to be meaningfully significant against cancer, it often requires pushing the body to levels of exertion that risk breaking it down further.
At this point, the benefits can reverse:
- Muscle trauma releases inflammatory signals and cellular debris that cancer can hijack.
Immune resources are diverted to tissue repair, leaving fewer defenses to fight tumours.
Oxidative stress and hydrogen ion accumulation increase local acidity in exercised tissues, creating an ideal milieu for cancer proliferation.
Excessive oxidative stress and acidosis from prolonged overtraining can mimic the metabolic chaos inside a tumour, tipping the balance in cancer’s favour.
It is not merely about increasing oxygen flow to a particular area, but rather about eliciting a controlled, localised metabolic activation — ideally experienced as a deep, internal burning sensation within the muscle. This sensation signals the precise biochemical shift that mobilises the immune system and triggers the release of myokines and lactate bursts that exert anti-tumour effects.
Where direct activation of the affected muscle is not possible due to tumour presence or fragility, the goal should be to stimulate adjacent or proximal muscle groups as close to the affected area as possible — inducing a similar local metabolic response without any secondary trauma or delayed-onset muscle soreness (DOMS). This distinction is crucial: it ensures the immune-stimulating benefits of intense exercise are achieved without the damaging inflammatory consequences of conventional training.
A further complication is that steady, low-intensity activity such as long walks—though excellent for cardiovascular health—produces little to no lactate burst. Without these sharp lactate pulses, the immune system is never fully activated to target cancer cells. This creates a gap: patients may engage diligently in conventional exercise yet still miss the very metabolic signal needed to mobilise the body’s defences against tumours.
It should, however, be noted that such activity is far more beneficial than inactivity, as long walks do improve inflammatory profiles and contribute to systemic health benefits that also support cancer care. Yet compared to high-intensity exercise, which more effectively mobilises NK cells and myokine responses, their cancer-specific immune impact may be limited.
📌 In short: while exercise is indispensable, conventional approaches carry a paradox — push too little, and the immune response is underwhelming; push too hard, and the resulting damage may hand cancer the conditions it needs to grow.
References & Further Reading
- Hekmatikar AHA, et al. (2025). Context Matters: Divergent Roles of Exercise-Induced and Tumor-Derived Lactate in Cancer. PMC.
- Chen J, Huang Z, Chen Y, Tian H, Chai P, Shen Y, Yao Y, Xu S, Ge S, Jia R. Lactate and lactylation in cancer. Nature.
- Bao, T., Wang, Z., He, W. et al. (2024). Analysis of immune status and prognostic model incorporating lactic acid metabolism-associated genes. Cancer Cell International.
- Deppe, I et al. (2025). The impact of a single HIIT intervention on the mobilization of NK cells and ILCs in adolescents and young adults undergoing cancer treatment: an interventional controlled trial. BMC Cancer.
- Clifford, B. et al. (2023). The effect of exercise intensity on the inflammatory profile of cancer survivors: A randomised crossover study. EJCI.
- Colegio OR, et al. (2014). Functional polarization of tumour-associated macrophages by tumour-derived lactic acid. Nature.
- Fischer K, et al. (2007). Inhibitory effect of tumor cell–derived lactic acid on human T cells. Blood.
- Romero-Garcia S, et al. (2016). Tumor cell metabolism: An integral view. Cancer Biology & Therapy.
- Brooks GA. (2020). The Science and Translation of Lactate Shuttle Theory. Cell Metabolism.
- Pedersen L, Idorn M, et al. (2016). Voluntary running suppresses tumor growth through epinephrine- and IL-6-dependent NK cell mobilization. Cell Metabolism.
- Li, J., Ma, P., Liu, Z. et al. (2025). L- and D-Lactate: unveiling their hidden functions in disease and health.
- Johns Hopkins Medicine. (2025, October 16). They found the switch that makes the body attack cancer.
