Athletic Genes and Talent: How Much Does DNA Really Decide? A Triathlon Coach's Honest Take

Coach’s Opening: The Athlete “Sentenced to Death” by a Genetic Test

A few years ago, a student in his early thirties, an office worker, came to me holding a commercial athletic genetic testing report, looking rather upset. The report stated his ACTN3 was “XX type,” and the conclusion column read in bold: “You are less suited for explosive and sprint-type sports; endurance disciplines are recommended.” He asked me, “Coach, am I just born unable to run fast or ride up Wuling? Should I just give up?”

I looked at the report and laughed. Because just three months earlier, another student had brought in a report with the exact opposite conclusion—“Exceptional explosive power talent”—and that “gifted” student, during the first climbing session on the Yangjin P-word Mountain Road, was dropped half a mountain away by this “sentenced to death” XX-type student.

I’ve coached athletes for fifteen years, from those finishing their first 51.5 standard-distance triathlon to those qualifying for the Kona World Championship. I can tell you this with full responsibility: Genes determine your “starting line” and your “ceiling range,” but they almost never determine whether you can be faster this year than last year. In this article, I want to use actual sports science research, combined with years of observations coaching athletes on Taiwan’s race courses, to have an honest discussion with you about “athletic talent”—it truly exists, but it has been severely distorted by commercial marketing.

If you’ve ever been discouraged by a genetic report, or have ever used “I have no talent” as an excuse, please read this article patiently to the end.

Conceptual Foundation: First Understand That “Heritability” Doesn’t Mean What You Think

Before discussing any genes, I must first clarify the most misunderstood term for you: heritability. The degree to which this term is misused is probably number one in the sports science world.

Heritability Refers to “Population Differences,” Not “Your Personal Percentage”

Many people think “VO2max heritability is 50%” means “half of your maximal oxygen uptake comes from your parents, and half comes from training.” That’s wrong. Heritability describes: within a specific population, what proportion of the “differences” between individuals can be attributed to genetic differences. It’s a statistic about “group variation,” and applying it to “one individual” is meaningless.

Here’s an analogy: In a rice paddy, the rice plants vary in height. If the seed genetics are very different but the soil and moisture are consistent, then the height differences mainly come from genetics (high heritability). But if the seeds are all the same, just some corners lack water, then the differences mainly come from the environment (low heritability). With the same batch of seeds, change the environment, and the heritability number changes. So heritability is not a fixed destiny; it changes with the population and the environment.

Several Research-Supported Heritability Numbers

According to meta-analyses of twin studies, when maximal oxygen uptake (VO2max) is calculated per kilogram of body weight, the weighted heritability estimate is approximately 72% (about 59% when calculated as an absolute value in ml/min). That means, within the studied population, a fairly high proportion of the differences in VO2max between people is related to genes. That sounds intimidating, as if endurance is predetermined by birth.

But the key lies in the next number.

What Really Matters: The Heritability of “Trainability”

Here we need to distinguish between two completely different things:

• Baseline value: How high your VO2max is “before you start training.”
• Trainability: How much you can improve “after you start training.”

The famous HERITAGE Family Study had 481 previously sedentary adults undergo 20 weeks of standardized endurance training. The results were striking: average VO2max increased by about 400 ml/min, but individual differences were enormous—some people barely improved (low responders, non-responders), while others improved by more than 1000 ml/min. More importantly, this “degree of improvement” showed clear familial aggregation: variation “between” families was about 2.5 times the variation “within” families.

This tells us two things:

1. With the same training plan, different people naturally improve at different rates, and this “ability to improve” itself has a genetic component (heritability of trainability estimated at about 40–50%).
2. But even with the same training stimulus, the vast majority of people “will improve”—just by different amounts. Those who truly show no response at all are a minority.

This is the key point: Talent affects the “rate” of your improvement, not “whether you can improve.”

ACTN3 and ACE: The Two “Sports Genes” Talked to Death

Commercial genetic tests love to boast about ACTN3 and ACE. Let’s break them down one by one.

ACTN3: The So-Called “Speed Gene”

The ACTN3 gene is responsible for producing a muscle protein called α-actinin-3, which is expressed almost exclusively in fast-twitch, glycolytic type IIX muscle fibers—the fibers that produce explosive, powerful contractions. ACTN3 has a famous R577X variant:

• RR / RX type: Can produce this protein normally, theoretically leaning toward explosive, sprint performance.
• XX type: Completely unable to produce α-actinin-3.

A multi-ethnic study spanning 10 countries, covering 346 elite sprinters and analyzing 555 personal bests, found that among Caucasian male sprinters, RR-type athletes had significantly faster 200-meter personal bests (about 21.19 seconds) compared to XX-type athletes (about 21.86 seconds). A Japanese study of 906 elite athletes also found that explosive/sprint athletes had a higher proportion of the R allele compared to endurance athletes and controls.

Sounds like the R type is the winner, right? Hold on. Modeling from the same body of research shows that the ACTN3 R allele explains only about 0.92% of the variance in sprint performance. You read that correctly—less than 1%.

The researchers’ interpretation of this “less than 1%” is quite interesting: At the world’s elite level, the gap between athletes is already minuscule, and that 1% might be the difference between “breaking a world record” and “only making the final.” But the premise of that statement is—you’re already among the top few dozen in the world. For 99.99% of us, including every amateur triathlete reading this, that 1% is completely drowned out by the massive variables of training volume, technique, nutrition, recovery, and mental toughness.

By the way, regarding endurance sports, there are also studies looking at the distribution of ACTN3 XX type (the type said to be “unsuited for explosive power”) among Ironman World Championship athletes. This also reminds us: in ultra-endurance sports, “not having the speed gene” is simply not a disadvantage.

ACE: The So-Called “Endurance Gene”

The ACE (angiotensin-converting enzyme) gene has two variants: I (insertion) and D (deletion):

• I type: Often associated with endurance performance.
• D type: Often associated with strength and explosive performance.

The multi-ethnic sprint study mentioned earlier also found that ACE variants affect elite sprint performance. But similarly, ACE’s explanatory power is very limited, and results often vary across different populations and studies—some studies simply fail to replicate. This is the most honest reality of sports genetics: the effect of any single gene is very small, and it often cannot be reproduced in other populations.

Why Are Single Genes So Unreliable?

Because athletic performance is polygenic. Current scientific consensus holds that there may be hundreds or even thousands of gene variants related to athletic performance, each with an extremely small effect, and they all interact with training, nutrition, sleep, and environment. Expecting one or two genes to predict whether you can ride up Wuling is like using a person’s shoe size to predict their annual salary—there might be a tiny statistical correlation, but using it for personal decision-making is absurd.

A Single Table: Heritability of Different Athletic Traits

I’ve compiled the research ranges for several common traits into the table below for your reference. Please note these are population-level estimate ranges, not a percentage of fate applied to you personally:

Trait	Heritability Estimate Range	Coach’s Plain-Language Interpretation
Height	~80%	Almost entirely innate; you can’t train for it
VO2max (per kg)	~60–72%	Baseline value is heavily influenced by genetics, but trainability is a separate matter
VO2max trainability	~40–50%	The magnitude of improvement varies innately, but nearly everyone improves
Muscular strength / power	Family studies ~0.27–0.58, twin studies ~0.14–0.83	Extremely wide range; enormous room for environmental (training) influence
Single genes (e.g., ACTN3) on performance	~1% or less	Virtually negligible at the individual level

Once you understand this table, you’ve got the key point: Genetics have the greatest influence on traits you can’t change anyway (like height); for strength and endurance improvements—the things most tied to training—the room for environmental influence and effort is very large.

Practical Approach: Instead of Testing Genes, Measure These

As a coach, if you came to me with a budget for genetic testing and asked how to spend it, I’d tell you to save your money and invest it in testing and monitoring that can actually guide your training. Here’s the priority order I actually use when planning for my athletes.

The “Testing” List Truly Worth Investing In

1. Laboratory or field VO2max / lactate threshold testing: This is your true physiological status “right now,” directly corresponding to training zones. It’s more useful than any genetic report.
2. FTP testing (functional threshold power): The most practical metric for cycling. Use a 20-minute test taking 95%, or do a Ramp Test, to calculate your training power zones.
3. Critical velocity / threshold pace for running: The core metric road runners use to set marathon and half-marathon paces.
4. Daily resting heart rate and HRV (heart rate variability): Reflects recovery status; tells you better than genes whether “today should be a hard day.”
5. Body composition and blood markers like ferritin: Endurance athletes especially need to monitor iron levels—this is a hundred times more important than your ACTN3 genotype.

A Sample Triathlon Weekly Plan Based on Data, Not Genes

Here’s a typical training week I set up for an amateur athlete preparing for a 113 half-ironman, with an FTP of ~220 watts and a running threshold pace of ~5:00 per kilometer. Note that this requires absolutely no knowledge of their genotype:

Day	Discipline	Content	Intensity / Zone
Monday	Recovery	Full rest or 1500m swim technique	Very easy
Tuesday	Bike	Main set: 4 × 8 minutes @ 205–215W, 4 min rest between	Threshold
Wednesday	Run	Aerobic long run 12km @ 5:40–5:55 per km	Zone 2
Thursday	Swim	Main set: 10 × 100m @ moderately hard pace	Threshold
Friday	Bike	Easy recovery ride 60 minutes	Zone 1–2
Saturday	Brick session	90km ride with climbs + transition to 4km run	Combined
Sunday	Run	Long run 20–24km, last 5km at marathon pace	Zone 2 to threshold

The logic of this plan is “build an aerobic base + one high-intensity stimulus per discipline + a brick session to adapt to transitions.” It applies to any genotype; the only difference is the rate of progress. I’ve coached athletes with the XX genotype following this exact logic, and they’ve steadily pushed their 113 split times forward.

Why Zone 2 Matters for Every Genotype

No matter what your genetic report says, low-intensity aerobic work (Zone 2) is the foundation of endurance sports. It develops mitochondrial density, capillaries, and fat metabolism capacity—these adaptations occur even in “non-responders,” just at a different rate. A common flaw among Taiwanese amateur athletes is “training too hard every session,” turning Zone 2 into Zone 3 and hitting a plateau. Instead of blaming your genes, first check whether your Zone 2 is truly slow enough and done in sufficient volume.

Genes Are Not Destiny: Epigenetics and “How Your Genes Get Used”

Many people think of genes as a fixed code written at birth that never changes. This is roughly true at the “sequence” level—the letter sequence of your DNA barely changes in a lifetime. But at the “expression” level, the story is completely different.

The Same Genes, Different Switches

Here we need to introduce a key concept: epigenetics. Simply put, your genes are like the keys on a piano, and the environment (training, nutrition, sleep, stress) determines which keys are pressed and how hard. On the same piano, someone can play a moving melody, while someone else produces only noise. Sports science has already observed that regular endurance training changes the “expression levels” of many genes in muscle cells—genes responsible for mitochondrial biogenesis, fat metabolism, and capillary growth get “turned up.”

In other words, the hand of genetic cards you hold is fixed, but how you play that hand is largely determined by your training and lifestyle. A person with a “less ideal” genotype, through consistent long-term training, can absolutely outperform someone blessed with great genes who sits on the couch. This isn’t motivational fluff—it’s what actually happens at the molecular biology level.

Why This Is Great News for Amateur Athletes

Because it means: every single training session you do today is genuinely reshaping your body’s ability to respond to exercise. You are not an object permanently fixed by a birth report, but a system that continuously adapts and rewrites its own physiological state. My favorite phrase to tell my athletes is: “Genes deal you the cards, but how this hand plays out is determined by your daily choices.”

Genetic Testing Products: Science for Science, Marketing for Marketing

With all that said, let’s seriously examine whether those commercially available “sports talent genetic tests” are worth buying. I’m not trying to dismiss them all outright, but I want you to be a smart consumer.

The Three Major “Scientific” Limitations of These Tests

1. Single-gene explanatory power is too low: As mentioned, star genes like ACTN3 typically explain less than 1% of performance variance. Using it to predict “whether you’re suited for a sport” is statistically so weak it’s nearly a guess.
2. Most don’t account for “trainability”: Commercial reports mostly look at your “current” static genotype, but can’t tell you the most important thing—“how much will you improve with training.” And the latter is what athletes really want to know.
3. Population applicability is questionable: Many studies were conducted on European or American populations or specific ethnic groups. Applying them directly to Taiwanese people raises serious accuracy concerns.

When Does Genetic Testing Actually “Make Sense”?

To be fair, genetic testing isn’t entirely worthless. In the following scenarios, it may have reference value:

• Health and injury risk aspects: Certain genotypes are associated with specific injuries (e.g., tendons, ligaments) or metabolic conditions. With interpretation by a medical team, it can serve as one reference dimension for personalized prevention.
• Pure curiosity and interest: If you simply enjoy learning about yourself, treating it as entertainment is fine—as long as you don’t use its conclusions to limit yourself or make major training decisions.
• Research contexts combined with complete physiological data: In the hands of a professional team, genetics is one of many inputs, not the sole decision-making basis.

But if a report directly tells you “you’re not suited for a certain sport, we suggest you give up,” please throw it in the trash. This kind of deterministic conclusion doesn’t hold up scientifically, and in coaching practice, it does real harm.

A Real Coaching Case: Three Years with Two “Genetically Opposite” Athletes

Let me use a composite coaching observation to tie together all the concepts above (the scenario is slightly reorganized for clarity, but the training logic and phenomena are all from my actual experience).

Athlete A: Genetic report indicated “sprint-type talent,” and early on he did excel at short-distance swimming and sprinting. But relying on his natural foundation, he trained sporadically—three days on, two days off—and never built a proper aerobic base for longer distances. Three years later, his 51.5 standard-distance triathlon results improved only marginally, and he fell apart on the run leg of every 113 half-ironman.

Athlete B: This is the athlete from the beginning who was “sentenced to death” by his XX-type report. He used that report as motivation instead and became even more consistent. Over three years, I had him focus on aerobic base, running economy, recovery management, and nutrition for eating out. His improvement curve was almost a perfect straight line, and he ultimately completed a 226 full ironman.

The contrast between these two sums up the core of this entire article:

Aspect	Athlete A (“Good Genes”)	Athlete B (“Bad Genes”)
Initial Advantage	Obvious	Not obvious
Training Consistency	Poor	High
Aerobic Base Development	Insufficient	Solid
Performance Trajectory After 3 Years	Plateaued	Steady improvement
Final Achievement	No breakthrough	Completed 226

Talent gets you in the door; discipline buys the ticket to the championship. I say this to every group of athletes I coach.

Three Training Principles Learned from This Case

Condensing the three years of Athletes A and B into actionable principles:

1. Aerobic base is the common foundation for everyone: No matter which type you’re classified as, long-duration, high-volume, slow-enough Zone 2 work is the root of endurance performance. Athlete A’s collapse was about 80% attributable to this.
2. Consistency beats explosiveness: Training steadily five times a week for three consecutive years accumulates adaptations that far surpass a sporadic week of high-intensity work followed by two weeks off. The body wants predictable, progressive stimulus.
3. Your weakness determines your ceiling: Triathlon is the sum of three sports, and your weakest discipline drags down the whole. Rather than sharpening what you’re naturally good at, invest resources in shoring up weaknesses—this has nothing to do with genes; it’s purely strategy.

Strength Training and Genes: An Often Overlooked Angle

Many endurance athletes neglect weight training, thinking, “I’m not trying to get bulky.” But strength is critical for cycling power, running economy, and injury prevention—and the heritability range for strength is quite revealing.

From the earlier table, the heritability of muscular strength/force ranges from approximately 0.27 to 0.58 in family studies and 0.14 to 0.83 in twin studies—this range is very wide. What does that width mean? It means environment (i.e., how you train) has more room to influence strength than it does for endurance. In other words, strength is a highly trainable, “plastic” capacity.

That’s why when I schedule two basic strength sessions per week for my triathletes, I never ask about their genotype:

Movement Category	Example Exercises	Recommended Sets/Reps	Purpose
Lower-body dominant	Squats, split squats	3 × 6–10	Cycling power, running propulsion
Hip hinge	Deadlifts, hip thrusts	3 × 6–10	Posterior chain, lower-back injury prevention
Single-leg stability	Single-leg squats, side planks	3 × 8–12/side	Running form stability, injury prevention
Core	Planks, bird-dogs	3 sets	Force transfer efficiency, posture maintenance

The key is progressive overload and movement quality, not how strong you naturally are. I’ve seen countless athletes who “thought they had no strength talent” double their squat weight after six months of consistent training and climb Wuling with noticeably more power on the climbs. Genes? Nobody ever asked.

Practical Details of Heat Acclimatization (Required Reading for Taiwanese Athletes)

Since we’re on the topic of trainability, let me get specific about heat acclimatization, which Taiwanese athletes need most. Heat adaptation is a classic “fully trainable” capacity that has almost nothing to do with genes:

• Progressive exposure: Two to three weeks before race day, schedule several sessions during hotter periods (but avoid the harshest midday sun) to teach your body to sweat and dissipate heat earlier and more efficiently.
• Hydration and electrolytes: In hot, humid conditions, hourly sweat rates can be substantial. During long training sessions or races, remember to consume sodium-containing sports drinks—don’t just drink plain water.
• Adjust by feel: On hot days, don’t obsess over power or pace. Heart rate and perceived exertion better reflect true load. Slow down when you need to and avoid heatstroke.

FAQ: The Gene Questions Athletes Ask Me Most

Q1: Should I spend money on athletic genetic testing?

If you’re an amateur pursuing health and finishing races, my answer is: Take that money and get a real FTP or threshold test instead—the return on investment is far higher. Unless you’re purely curious, it won’t help much with training decisions.

Q2: Neither of my parents exercises. Am I born without athletic ability?

Parents who don’t exercise are usually an “environment” issue rather than a “genetic” one—they simply never developed the habit. You could easily be carrying solid potential that no one in your family ever tapped into. Don’t equate “no one in my family exercises” with “my genes are bad.”

Q3: If I’m a “non-responder,” is training pointless?

True non-responders to all training stimuli are extremely rare. Most so-called non-responders simply respond poorly to one specific type of workout. Switching training methods or extending the time frame usually breaks through. And performance improvement isn’t measured by VO2max alone.

Q4: Should I have my child genetically tested to choose a sport?

Strongly not recommended. Using a report with extremely low explanatory power to limit a child’s sporting choices could stifle their genuine interests and potential. Let children try many things and find what they love—that matters far more than any genetic report.

Q5: So are elite athletes just born that way?

World-class athletes are typically the result of both “rare favorable genes” and “near-perfect long-term training and environment”—both are indispensable. But this has almost nothing to do with the daily training decisions of amateurs like us.

Common Mistakes and Corrections

What pains me most over the years isn’t athletes who can’t train hard—it’s those who box themselves in with a misguided “talent mindset.” Here are the landmines I most often have to help athletes defuse.

Mistake 1: Using a Genetic Report as an Excuse to Give Up

Symptoms: “I’m XX-type, so sprinting is hopeless. Training won’t help.”

Correction: The data above makes it clear: a single gene typically explains less than 1% of performance variance, while the gap between you and elite athletes is tens of percentage points of training volume and technique. Your ceiling is far higher than you think, and you haven’t even touched half of it. Replace “I have no talent” with “this trait of mine improves more slowly, so I need to accumulate patiently.”

Mistake 2: Using a Genetic Report as a Reason for Complacency

Symptoms: “I’m RR-type, born explosive, so I can slack off in sprint sessions.”

Correction: Talent is “unrealized potential”—skip training and you’ll regress just the same. I’ve seen too many “talented” athletes slack off on systematic training because they relied on their natural gifts, only to be overtaken by diligent “untalented” athletes. Genes give you an initial advantage, not a permanent get-out-of-jail-free card.

Mistake 3: Believing “Non-Responder” Means Training Is Useless

Symptoms: “Studies say non-responders exist. If my VO2max isn’t going up, am I one of them?”

Correction: So-called VO2max “non-response” is often poor response to one specific training stimulus. Switching training methods (e.g., from steady aerobic work to high-intensity intervals, or vice versa) usually breaks through. And even if VO2max doesn’t rise, it doesn’t mean your lactate threshold, running economy, or race performance haven’t improved—they often have. Don’t sentence yourself to death based on a single metric.

Mistake 4: Ignoring the “Gene × Environment” Interaction

Symptoms: Fixating only on genes while ignoring sleep, nutrition, stress, and recovery.

Correction: No matter how good your genes are, they won’t express themselves if you’re sleep-deprived, eating poorly, or under chronic stress. The biggest bottleneck for Taiwanese working athletes has never been genes—it’s insufficient sleep and imbalanced nutrition from eating out. Instead of spending money on genetic testing, first lock in 7+ hours of sleep and replace haphazard convenience-store eating with planned fueling.

Taiwan Context: Eating Out, Climate, and Local Race Courses

Most sports genetics research is conducted on European, American, or Japanese populations. Applying it to us requires factoring in Taiwan’s actual environment.

Humid, Hot Climate Makes the “Training Environment” a Bigger Variable

Taiwan’s summers are humid and hot, and this impact on endurance performance far outweighs that 1% from your genotype. The same person riding in 30°C humid heat at Guandu versus a dry, cool 18°C morning can see a huge difference in power output. So instead of obsessing over genes, learn heat adaptation: progressively increase heat exposure, hydrate and replace electrolytes during races, and adjust intensity based on feel rather than power numbers alone. The benefits from these acquired adjustments are something no genetic report can give you.

Eating Out Tests Your Nutritional Discipline

Taiwan’s convenience stores and street food are convenient, but they also make it easy to unknowingly consume excess carbs, insufficient protein, and too much sodium. I often tell my athletes: Your genes don’t decide your three meals, but your three meals decide your training quality every single day. A planned eating-out strategy (e.g., replenishing carbs plus protein after training, controlling refined sugar in daily life) does far more for your progress than knowing whether you’re RR or XX.

Local Race Courses Are the Best Testing Ground for Talent

Wuling, Fengguizui, Yangjin P-Road, Beihong, Eastbound Wuling—these classic Taiwanese routes are where your training is truly put to the test. I always encourage athletes to regularly use the same climb (e.g., Fengguizui starting from the National Palace Museum) as a “homemade test,” timing it once a month. You’ll find that progress is genuinely earned through effort, and it has nothing to do with that genetic report you got.

Actionable Advice for Athletes at Different Levels

Finally, let’s turn the concepts above into things you can do today.

For Beginners (First triathlon, first time finishing a race)

• There’s absolutely no need to get sports genetic testing. You’re still very far from your ceiling, and genetic limitations aren’t even close to coming into play.
• Focus on “consistency” and “aerobic base”: three to four sessions a week, mostly easy, with gradual progression.
• Establish quantifiable baselines: record your resting heart rate and times on a fixed route. These numbers are ten thousand times more honest than a genetic report.

For Intermediate Athletes (Several races completed, aiming to break personal records)

• Invest in real physiological testing (FTP, threshold, and VO2max if needed), and use the data to set your training zones.
• Do individualized training targeting your weaknesses: if your VO2max is improving slowly, try a different training stimulus instead of grinding the same workout plan.
• Start taking recovery and nutrition seriously: HRV monitoring, sleep, blood tests for iron and other markers—these now offer the highest marginal returns.

For Elites / Those Chasing a Kona Slot

• At this level, genotype “might” start to mean a little something—but only to help you understand your preferred training direction, not to limit you.
• Your winning edge still comes down to: training load management, race strategy, injury prevention, and mental toughness. None of these is something a genetic report can handle for you.
• If you’re genuinely curious about your genes, treat it as “one more reference dimension,” not “a predetermined fate.”

A Simple Self-Questioning Checklist

Next time you want to blame (or credit) your genes, first ask yourself these questions:

1. Has my training volume this month really been sufficient?
2. Have I done enough Zone 2 work, and done it slow enough?
3. Am I averaging 7 hours of sleep?
4. Do I have a plan for my nutrition and eating out?
5. When was the last time I did real physiological testing?

I can almost guarantee that if you can’t answer even one of these well, it means—your bottleneck hasn’t even gotten to the point where genes come into play.

Conclusion: Talent Sets the Floor, Effort Determines How Far You Go

Back to that athlete who was “sentenced to death” by a genetic report. Two years later, he finished his first 226 ultra-triathlon, and his split times surpassed the “genetically gifted” training partner from back then. He later told me with a laugh: “Coach, good thing I didn’t believe that piece of paper back then.”

Athletic talent is real—I won’t deny that. Some people are simply born with faster progress, better recovery, and higher ceilings. But scientific research tells us again and again: at the amateur level, and even up to the semi-elite level, what determines your results has never been your genes—it’s how consistently, how intelligently, and how patiently you train. Genes determine where your starting line is, but how far this road can take you and how high you can climb is in your own hands.

So stop using that piece of paper as an excuse, and don’t use it as a get-out-of-jail-free card either. Ride, run, swim—write your own “test report” with the sweat you shed on the course.

See you on the mountain.

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This article is educational content and does not replace individual assessment by a physician, physical therapist, or nutritionist. If genetic testing involves disease risk, please consult a qualified medical professional.

References

• Multi-ethnic study of ACTN3 R577X and ACE I/D on elite sprint performance: https://pmc.ncbi.nlm.nih.gov/articles/PMC4831144/
• The role of ACTN3 R577X in sprint and power performance (review): https://pmc.ncbi.nlm.nih.gov/articles/PMC4322025/
• Twin-sibling study and meta-analysis of VO2max heritability: https://pmc.ncbi.nlm.nih.gov/articles/PMC4773888/
• HERITAGE Family Study: familial aggregation of VO2max response to training: https://journals.physiology.org/doi/full/10.1152/jappl.1999.87.3.1003

Related Reading

• The Meaning of Sports Genetic Testing for Training: What ACTN3 and ACE Genes Tell You
• Sports Genetics: The Impact of ACTN3 and ACE Genes on Endurance Performance
• The Genetics of Running: How ACTN3 and ACE Genotypes Affect Running Ability
• The Impact of Gene Polymorphisms on Training Response: Sports Genetics Research on ACTN3, ACE, and EPAS1