Masters runners
Evidence: moderate
Endurance declines slowly from the mid-30s and faster past 60, driven by falling VO2max, maximal heart rate and muscle mass. Intensity and strength work preserve more than easy volume alone, and trainability persists into old age.
A masters runner is, by the usual convention, one aged 35 or older. Performance does decline with age, but the curve is gentler than most fear, and a large part of it reflects how people train rather than age itself.
The shape of the decline
Endurance performance holds up to about 35, falls modestly to 50 or 60, then drops more steeply (Tanaka & Seals 2008). In the broad middle decades the loss runs at roughly 1% a year, accelerating to nearer 1.5 to 2% a year after 60 (Tanaka & Seals 2008). The decline is curvilinear, not a steady slide, so the steep part arrives later than a straight-line projection would suggest.
What drives it
Three physiological changes do most of the work.
- Falling VO2max. The aerobic ceiling drops by roughly 5 to 10% per decade after 30, and it is the main driver of lost performance (Tanaka & Seals 2008).
- A lower maximal heart rate. Maximum heart rate falls at about 0.7 beats per minute per year, regardless of sex or training, which lowers maximal cardiac output and feeds directly into the VO2max decline (Tanaka, Monahan & Seals 2001).
- Loss of muscle mass. Sarcopenia strips muscle, preferentially the fast-twitch fibres, which erodes power and the ability to hold faster paces (Fragala et al. 2019).
Recovery also slows. Older runners need longer between hard sessions, which constrains how often they can train at the intensities that matter most.
Training matters more than age
How much capacity is lost depends heavily on training. Around half the variance in the rate of VO2max decline among ageing athletes is explained by changes in training volume, and athletes who keep training lose capacity at roughly half the rate of sedentary peers (Valenzuela et al. 2022). Much of what looks like ageing is detraining in disguise, the same process described under detraining.
Intensity preserves more than easy volume
Older track athletes who kept training at intensity held their VO2max roughly steady despite a falling maximal heart rate, while those who dropped intensity and coasted on easy mileage lost capacity (Pollock et al. 1997). Hard sessions, not just accumulated easy miles, defend the aerobic ceiling. This mirrors the wider case for intensity over sheer volume.
Strength training and trainability
The muscle loss of ageing is partly modifiable. Strength training counters sarcopenia, preserving the fast-twitch fibres and the power that easy running neglects (Fragala et al. 2019). The encouraging finding is that trainability persists: older adults still gain strength, power and muscle mass in response to resistance training, so the adaptive machinery does not switch off with age (Fragala et al. 2019). Individual variation is wide, so masters runners differ more from each other than younger runners do, and training history explains much of the spread.