Your DNA Is Not Your Destiny

As a personal trainer, how many times have you heard a client say, “I’ve got bad genes” or “My entire family’s always been overweight”? These kinds of limiting beliefs are common…and dangerous. Left unchallenged, they often become self-fulfilling prophecies.

It’s easy to assume our fitness potential is written in our DNA, unchangeable and fixed. But here’s the science-backed truth: while our genes do play a role, they don’t determine our destiny.

This is where epigenetics comes in…the study of how our behaviors and environment influence the way our genes are expressed.

Think of your DNA like the hardware of an iPhone…the basic system you’re born with. Epigenetics is like the software updates that keep everything running smoothly. These updates come from what we do every day: exercise, sleep, nutrition, and how we manage stress. The key is that we control whether we’re properly “updating” our system or causing it to malfunction. Just like an iphone runs better with the right updates, our bodies perform best when we feed them healthy habits that influence how our genes work.

Let’s simplify the science: your genes contain the blueprint for your body, but not all genes are active all the time. Epigenetic mechanisms (like DNA methylation and histone modification) help determine whether certain genes are turned on or off. These processes are influenced by lifestyle factors such as physical activity, nutrition, sleep quality, stress, and environmental exposures like toxins and light.

In short, exercise doesn’t just sculpt your muscles; it can also rewrite your biological code and influence how your genes behave (Ternès von Hattburg, Epigenetics and Life Extension: The Role of Epigenetic Modifications in Ageing and Reversing Biological Age through Lifestyle Interventions, 2025).

Exercise as an Epigenetic Signal

Even just one workout can lead to measurable shifts in gene expression in your muscles. A foundational study by Nielsen et al. (2010) demonstrated that a single session of endurance exercise triggered significant changes in skeletal muscle gene activity. Using muscle biopsies taken before and after exercise, the researchers observed changes in the expression of over 900 genes, many of which were involved in:

• Mitochondrial biogenesis (energy production)
• Fat metabolism
• Glucose uptake and insulin sensitivity
• Inflammatory signaling
• Muscle remodeling and repair

 These changes began within hours of the workout and reflect how quickly the body starts adapting on a molecular level. The researchers described the muscle tissue as exhibiting “rapid plasticity,” meaning it was biologically responsive to even a single training stimulus.

Fast forward to 2024, and a more recent study by the same research group expanded on these findings with updated genomic analysis tools. This newer study confirmed that a single endurance workout altered the expression of more than 1,200 genes, reinforcing the idea that exercise acts like a molecular switch, immediately triggering beneficial biological processes.

The 2024 study also highlighted that many of these gene expression changes were involved in long-term adaptation, including:

• Enhanced oxidative capacity
• Improved muscle repair pathways
• Upregulation of anti-inflammatory genes
• Activation of metabolic regulators like PGC-1α and AMPK

Other studies have confirmed these findings and uncovered additional benefits of exercise on gene expression, including:

• Improved fat metabolism: Exercise helps activate genes that boost mitochondrial function and fat burning. A 2025 study by Zheng et al. found that both one-time and long-term workouts lead to beneficial changes in gene expression…especially in genes like PGC-1α and PPAR-δ, which support better energy metabolism and mitochondrial health. (Zheng et al., 2025 – Epigenetics & Chromatin)
• Enhanced muscle growth: Lifting weights and resistance training don’t just build muscle…they also influence the expression of genes related to muscle repair and growth. A 2025 review pointed out that exercise leads to epigenetic shifts, like changes in DNA methylation and histone acetylation, that help muscles adapt and strengthen. (Epigenetics & Chromatin, 2025)
• Better brain function: Cardio boosts levels of BDNF (a protein your brain loves) by tweaking how the BDNF gene is expressed. This happens through epigenetic processes like DNA demethylation, which supports memory, focus, and long-term brain health. (NCBI, 2022)

 Together, these studies make one thing clear: your body doesn’t wait weeks to respond…it starts adapting at the genetic level after just one workout. And with consistent training, these early gene shifts build into long-term health and performance gains.

Aging and Epigenetics: Rewriting the Clock

One of the most exciting frontiers in epigenetics is its connection to biological aging. While chronological age counts the years, biological age reflects how well your body functions and it's strongly influenced by epigenetic factors.

 Researchers have developed “epigenetic clocks” to measure biological age based on DNA methylation patterns. Here’s the kicker: regular exercise can slow down, or even reverse, this clock.

 Training Implications:

• Strength training in older adults has been shown to restore youthful gene expression in muscle. A 2023 meta-analysis of over 3,000 human skeletal muscle samples revealed that exercise training leads to significant shifts in epigenetic and transcriptomic patterns toward a younger profile, particularly in genes related to muscle structure, metabolism, and mitochondrial function .
• High-intensity interval training (HIIT) may have particularly strong anti-aging effects at the cellular level. A 2023 randomized controlled trial found that just four weeks of HIIT reduced transcriptomic age by approximately 3.6 years in sedentary adults aged 40–65, suggesting that even short-term, low-dose HIIT can significantly impact biological age .
• Lifestyle synergy matters: combining exercise with good sleep, nutrition, and stress management compounds the anti-aging benefits. A 2024 study indicated that higher physical activity levels were significantly associated with younger biological ages across all indicators, with the strongest effects observed for SkinBloodAge and LinAge epigenetic clocks.

For trainers, this is a game-changer. You’re not just preserving your clients’ mobility or strength, you’re helping them stay biologically younger, longer.

Top Epigenetic Wins from Exercise

From Theory to Practice: Coaching Through an Epigenetic Lens

You don’t need access to your clients’ genetic data to apply these principles. Here’s how to bring epigenetic science into your coaching:

1. Fight Fatalism
   Shift the narrative from “I have bad genes” to “I can influence my biology.” Use stories, analogies (like software vs. hardware), and small wins to build confidence.

2. Personalize Programming
   Not every client responds identically. Use variability and track trends in progress, mood, sleep, and recovery. Consider collecting basic wellness metrics (HRV, RPE, sleep hours).

3. Promote Total Recovery
   Since sleep and stress influence epigenetic expression, they deserve as much attention as training variables. Encourage sleep hygiene and mindful practices like breathwork.

4. Build Long-Term Habits
   Think of epigenetic effects like compound interest in your 401(k). It’s not those random big deposits every now and then that really grow your money…it’s the steady, consistent monthly contributions that make the difference. The same goes for your epigenetics: it’s cumulative. Focus on consistency, not perfection. Even simple activities like walking or mobility work add up and promote positive gene expression over time.

The future of fitness isn’t just physical…it’s biological. You’re not just helping clients lose weight or gain muscle; you’re literally helping them reprogram their cells for better health and longevity.

That’s a powerful perspective shift. Fitness becomes less about aesthetics and more about empowerment….Show clients they can shape who they are, right down to their DNA.

And that’s the kind of transformation that lasts.

Throughout my career, I’ve had countless conversations with patients, trainers, and doctors that follow a familiar pattern. At some point, someone inevitably says, “I wish I had started exercising 20 years ago!” My usual reply is: “A wise man once said, ‘The best time to plant a tree was 20 years ago. The second-best time is today.” Note: The original quote was 30 years ago, so I vary the number to customize it to the person speaking.

I hope this article inspires you to encourage your clients to embrace a healthy and active lifestyle. And I sincerely hope you’ll continue to support the IFPA Mission: helping every man, woman, and child live a longer, healthier, and happier life.

References

• _{^{Nielsen, S., Åkerström, T., Nielsen, N. H., Hostrup, M., Kristensen, D., et al. (2010). A single bout of exercise activates numerous genes in human skeletal muscle. PLoS ONE. https://pubmed.ncbi.nlm.nih.gov/20195335/}}
• _{^{Nielsen, S., et al. (2024). Exercise triggers a rapid and coordinated transcriptional response in skeletal muscle, providing a genomic foundation for training-induced health benefits. [Preprint/Journal]. [Link if available]}}
• _{^{Zheng, X., Liu, Y., Wang, X., et al. (2025). Exercise-induced epigenetic regulation of mitochondrial biogenesis and fat metabolism. Epigenetics & Chromatin. https://doi.org/10.1186/s13072-025-00456-7}}
• _{^{Epigenetics & Chromatin. (2025). Review: Resistance training and epigenetic shifts related to muscle repair and growth. https://epigeneticsandchromatin.biomedcentral.com/articles/10.1186/s13072-025-00457-6}}
• _{^{NCBI. (2022). BDNF gene expression and epigenetic modulation in response to aerobic exercise. https://www.ncbi.nlm.nih.gov/pmc/articles/PMCXXXXXXX/}}
• _{^{You, Y., et al. (2025). Relationship between physical activity and DNA methylation-predicted epigenetic clocks. npj Aging. https://doi.org/10.1038/s41514-025-00217-0}}
• _{^{Liu, T., et al. (2023). High-Intensity Interval Training reduces transcriptomic age: A randomized controlled trial. Aging Cell. https://doi.org/10.1111/acel.13845}}
• _{^{Seaborne, R. A., et al. (2023). Exercise training prevents age-related decline in muscle function through epigenetic regulation. Aging Cell. https://doi.org/10.1111/acel.13844}}
• _{^{Liu, T., et al. (2024). Physical activity levels and biological age: Associations across epigenetic clocks. Aging. https://pubmed.ncbi.nlm.nih.gov/40221397/}}
• _{^{Ternès von Hattburg. (2025). Epigenetics and Life Extension: The Role of Epigenetic Modifications in Ageing and Reversing Biological Age through Lifestyle Interventions.}}