Last reviewed: May 12, 2026 Last updated: May 12, 2026

Written by: Jay Hastings , CEO of PlexusDx

Jay Hastings is the CEO of PlexusDx, a precision health company focused on genetic testing, blood biomarker insights, and personalized wellness recommendations. He has more than 20 years of experience across healthcare innovation, genomics, laboratory operations, healthcare investing, and strategic finance. His work has included scaling healthcare startups, leading CLIA lab integrations, and helping expand consumer access to precision health tools.

Medically reviewed by: Jayden Lee, PharmD, EMBA

Jayden Lee, PharmD, EMBA, is the PlexusDx Medical Science Liaison with a PharmD and MBA specializing in pharmacogenomics and clinical product development, with a proven ability to bridge the gap between genomic research and practical patient outcomes. Dr. Lee has more than 10 years of professional experience in clinical pharmacy, academia, and research.

This article is part of the PlexusDx Education Hub — your resource for evidence-based guidance on fitness & genetics. Browse all Fitness & Genetics education

Aerobic capacity — often measured as VO2 max, the maximum rate at which your body can use oxygen during hard effort — is one of the most reliable markers of overall fitness. It reflects how well your heart, lungs, blood, and muscles cooperate to deliver and burn oxygen. Higher aerobic capacity tracks with better endurance, faster recovery, and, in large population studies, better long-term health outcomes. This article covers why it matters and the evidence-based ways to raise it.

What aerobic capacity actually measures

VO2 max captures the full oxygen-delivery chain: how much blood the heart pumps per beat, how efficiently the lungs load oxygen, how much oxygen the blood carries, and how well muscle mitochondria extract and use it. Because so many systems feed into that number, aerobic capacity is a strong summary statistic for cardiovascular and metabolic fitness rather than a measure of any single organ.

Why higher aerobic capacity is worth pursuing

The benefits extend well beyond athletic performance. Greater aerobic capacity is associated with a lower resting heart rate, improved blood pressure and blood sugar regulation, better mood and cognition, and faster recovery between efforts. Across large cohorts, cardiorespiratory fitness is one of the strongest predictors of long-term health — which makes it a worthwhile target for almost anyone, not only competitive athletes.

Evidence-based ways to enhance it

Aerobic capacity is highly trainable. The most effective strategies combine two ingredients. First, a base of steady, moderate-intensity aerobic work — brisk walking, cycling, swimming, or jogging — that builds cardiovascular efficiency and mitochondrial density. Second, higher-intensity intervals: repeated bouts of hard effort with recovery in between, which are especially potent for pushing VO2 max upward. Consistency matters more than any single session, and adequate sleep, protein, and recovery let the adaptations take hold.

Progress is gradual and individual. Two people following the same program can improve at different rates, and that variability is partly biological.

The genetic layer behind trainability

Research on endurance and trainability points to several named genes. PPARGC1A, which encodes the regulator PGC-1α, is central to mitochondrial biogenesis — the process of building more of the cellular machinery that burns oxygen — and its activity rises in response to endurance training. The ACE insertion/deletion polymorphism has been associated in multiple studies with endurance phenotypes, with the insertion (I) allele linked to endurance advantages. And ACTN3, the so-called sprint gene, influences muscle fiber composition; the R577X variant shapes the balance between fast- and slow-twitch fibers that underlies power versus endurance leanings.

These variants describe tendencies, not ceilings. Genetics helps explain why baseline capacity and training response differ between individuals, but nearly everyone improves with consistent aerobic work.

Where genetic insight fits

Understanding pathways tied to mitochondrial function, muscle fiber type, and cardiovascular signaling can add useful context to how you train — as a guide, not a guarantee. The Precision Peptide Genetic Test analyzes 14 pathways, 49 peptides, 150+ genetic insights, offering pathway-level education about the biology behind energy metabolism and physical performance. It does not diagnose any condition or predict your exact VO2 max; it gives you informed background to discuss goals with a coach or healthcare provider.

Frequently Asked Questions About Aerobic Capacity

How long does it take to improve aerobic capacity?

Most people see measurable gains within six to twelve weeks of consistent training that mixes steady aerobic work with higher-intensity intervals. The rate of improvement varies by starting fitness, age, and genetics. Beginners often improve fastest, while well-trained individuals see slower, smaller gains as they approach their personal ceiling.

Is aerobic capacity mostly genetic?

Both genes and training matter. Studies suggest inherited factors influence baseline aerobic capacity and how much it responds to training, with genes like PPARGC1A and ACE involved. But aerobic capacity is highly trainable, and consistent effort raises it substantially in nearly everyone, regardless of genetic starting point.

What is the fastest way to raise VO2 max?

Combining a base of moderate aerobic exercise with high-intensity intervals is the most effective approach. Intervals — repeated hard efforts with recovery — are especially potent for pushing VO2 max upward, while steady work builds the mitochondrial and cardiovascular base. Recovery, sleep, and consistency let those adaptations accumulate.

Does the ACTN3 gene affect endurance?

ACTN3 influences muscle fiber composition through the R577X variant, shaping the balance between fast-twitch power fibers and slow-twitch endurance fibers. It describes a tendency, not a limit. Endurance depends on many genes plus cardiovascular fitness and training, so ACTN3 alone does not determine your aerobic potential.

Curious how your genetics fit into the bigger picture? Explore the Precision Peptide Genetic Test for pathway-level insight you can bring to a conversation with your healthcare provider.

The Precision Peptide Genetic Test analyzes how your genes influence peptide-related biological pathways. It does not recommend, prescribe, or determine which peptides you should use, and it does not diagnose, treat, cure, manage, or prevent any medical condition. Consult a qualified healthcare provider before beginning any peptide protocol or making changes to your care.

Medical and Editorial Standards

Medical review process: This article was reviewed for medical accuracy, scientific clarity, evidence alignment, and appropriate discussion of genetics, medications, supplements, biomarkers, and health-related claims.

Sources and evidence: PlexusDx educational content is developed using peer-reviewed research, clinical literature, reputable medical references, and, where applicable, public health or regulatory guidance. References are included at the end of the article when scientific, medical, or health-related claims are discussed.

Commercial transparency: PlexusDx offers genetic testing, blood biomarker testing, personalized supplement recommendations, and related precision wellness services. Product mentions are intended to help readers understand available options and should not be interpreted as medical advice.

Important disclaimer: PlexusDx educational content is for informational purposes only and should not be used as a substitute for professional medical advice, diagnosis, or treatment. Always consult a qualified healthcare provider before making decisions about medications, supplements, genetic testing, lab testing, or health-related care.

This article is part of the PlexusDx Education Hub. Browse all Fitness & Genetics education