How Much Slower Will You Get As You "Age Up" in Triathlon? – Triathlete
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How much slower do we get as we “age up” in our triathlon lifespan? We crunched the average swim, bike, run, and overall finishing times for 70.3 and Ironman athletes to analyze the trends. Photo: Triathlete
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While there's no defined age limit for setting a PR, there's also the reality that at some point your ability to hit that PR declines, especially if you've been doing this sport for a while. Looking at the results after a race we tend to see the same age groups finishing at the top of the overall standings. When, exactly, do Ironman and 70.3 triathletes hit their peak? How much faster, or slower, can we expect to get as time goes by? We look at the data from the last few years to see what the chances are for getting a new PR as we get older.
We looked at the finishing times for all Ironman races between 2021 and 2023 and looked at the averages by age group. Both men and women peak while in the 30-34 age group (12:04 and 12:54, respectively), although women in the 25-29 group are only four minutes behind. After that peak, both men and women slow down by about 2.5% every 5 years. This means we are on average 15 minutes slower in the next decade after we peak, 30 minutes slower in the decade after that, and a full hour for each subsequent decade.
This pattern is not exactly the same across the three disciplines. If you're in your 30s, it's likely you have already had your fastest swim, which for the last three years peaked in the 25-29 category (1:14 for men, 1:16 for women on average); in the three years before the pandemic, the fastest times were found in the 18-24 age group. For women, the slowdown in swim is a lot more linear (about one minute slower every five years), whereas the men get slower at a slightly accelerated rate: First it’s 30 seconds slower, then 45, then 60….
The bike leg belongs to triathletes in their 30s. Women in the 30-34 group are once against the fastest in this segment (6:39), but the fastest male cyclists are actually in the 35-39 (6:08), just one minute faster than the younger group. From there, once again the women slow down more gradually (1.7% slower with each subsequent age group), while the men slow a lot more (2.4%), though the gap between men and women remains more or less the same with age.
Finally, on the run, fastest marathon times go to the 30-34 age group for both men and women. Whereas with swimming we slow down 1.7-2.4% every five years, on the run both genders get 3.5% slower with each passing age group. This means, for example, that men are 10 minutes slower in their early 40s compared to their early 30s, will become 20 minutes slower in their 50s, and around 60 minutes slower ten years after that.
Over in the 70.3 world, things are a lot less homogenous. Overall, this is a younger person’s sport. Both men and women are fastest in their 20s, and the difference between average finishing times in the two genders is less than 20 minutes (5:44 for men and 6:09 for women)! Both genders slow down exponentially as years go by. Triathletes in their 30s are only three to six minutes slower than their peak, but triathletes in their 60s are around a full hour behind.
The real variance comes in each of the three legs for 70.3. The fastest swims goes to the youngest among us, and we get around 2% slower as we move up each age group.
On the bike, there is no clear peak, as the difference in average bike times among triathletes between 25 and 44 can be counted in seconds. For men, the 35-39 group was technically fastest, with a time of 2:55:46 (the next fastest is the 40-44 age group with 2:56:10), whereas the fastest women are in their 30s, with a time of 3:12 for both 30-34 and 35-39. The decline, compared to the other disciplines, is much more gradual, and only really picks up past our 60s.
Finally, the run is again ruled by the young ones. Men between 18 and 35 were finishing their runs with a time of 2:02, and women peaked in their late 20s with a time of 2:11 – though the age groups on either side were close behind with a time of 2:12. By the time we are racing in our 70s, we will be around 45 minutes slower than we were at our peak, or 33%, according to the data.
We've seen the numbers behind age-related slowdowns, but what about the “why” behind them? Understanding the physiology of why triathletes slow down as we age can help us understand how to thrive, no matter what number is on your calf.
One of the main causes of age-related slowdowns across all disciplines is a decrease in VO2 max, or the maximal rate of oxygen a person can use while exercising. Between the ages of 30-80, VO2 max decreases by about 7% each decade in trained runners, due to normal age-related declines in maximal heart rate and stroke volume. This is in line with our data analysis, which found the average difference in splits hovers around 7%, though it's actually a difference that gets bigger as we get older (in other words, this is not a linear decline). See the table below for a breakdown of time split differences by age and sex.
Run split difference by age
The ability of the muscles to use oxygen from the blood decreases as well. Submaximal efforts are also impacted, as speed at lactate threshold decreases.
Without intervention, muscle strength peaks in our 20s and decreases by 3-8% per decade afterwards, with this loss accelerating after the age of 60 – unsurprisingly mirroring the data on 70.3 bike times for athletes 60 years old and older. Muscle cells become smaller, fewer in number, less organized, and less excitable. Muscle power, or the ability to generate force quickly, is especially affected. A marked loss of calf muscle strength and Achilles tendon springiness occurs. The calf muscles are most responsible for producing propulsion while running, so this contributes to decreased stride length, with a stride length reduction of 13% seen between the ages of 20 and 60, accelerating to 20% by the age of 80.
As many athletes can attest, staying (relatively) healthy becomes trickier with age. Although scientific evidence is mixed, triathletes often feel that as we age, recovery just gets harder. Collagen production and protein synthesis decrease, and lowered immune function can blunt the healing process. Masters runners have been seen to have increased injury rates and a higher risk of sustaining multiple injuries. In addition to losing strength, the calf/Achilles complex becomes particularly vulnerable to injury.
Women of a certain age face a particular challenge with the onset of menopause. Dropping estrogen and progesterone levels contribute to many of the aforementioned factors – muscle strength loss, decreased protein synthesis, decreased VO2max. Along with the physical symptoms of menopause (hot flashes, night sweats, mood changes), cortisol levels rise, fat storage increases, and bone density is lost. Men are not immune to hormonal changes, either – although it’s not as abrupt as menopause, some testosterone loss begins to occur in the 40s, leading to issues with muscle mass and bone loss.
Finally, there’s just the simple fact that priorities shift over time, and the training levels that young, eager athletes were able to maintain may not be possible or desired. Between increased career, home, and family obligations or just new interests and hobbies, performance decrements can and will occur when training load is reduced.
When it comes to combating slowdowns, “use it or lose it” comes into play, as the rate of VO2 max decline is the least in athletes who maintain the highest training. This also applies to strength. Older athletes should focus on high-weight, low-rep heavy resistance training to maintain muscle mass, bone mineral density, and tendon health (these exercises can help). Calf work should be a focus for aging runners – and don’t neglect that power aspect! Simple hopping and jumping exercises can help.
Nutritionally, older athletes can benefit from working with a registered dietitian to address their changing needs. A triathlon coach can also come in handy for older athletes, who need to be more meticulous with careful training load layout and day-to-day recovery strategies.
Regarding adjusting goals, endurance performance decrements occur later and more slowly than losses of peak speed. Athletes can chase high-level performances in longer events, where the durability and experience built over years of training play a larger role.
Still, time eventually catches up. Aging in sport requires a shift from lamenting performance decrements, to accepting the inevitable while maintaining an open-mindedness and sense of curiosity toward discovering what still is possible – all while appreciating the ability to continue to train and compete. Goals should become more process-oriented, with a focus on the controllables: mindset, effort, execution, and recovery. Age-group competition is always there for added motivation and drive.
But even if you aren't racing for a PR, there's a lot of value in staying fit through swim-bike-run. Strength and cardiovascular capacity (VO2max) contribute to an individual’s ability to live independently well into their later years, so staying fit with aging becomes not just an investment in race times, but in overall quality of life. After all, an older athlete will still be more fit than a younger sedentary individual. Athletes can and should continue to find joy and satisfaction in the simple act of movement, as well as the experiences and camaraderie that sport provides at any age.
Taylor Knibb's first Ironman was full of curveballs, but she talks about how she kept smiling (almost) until the end.
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