The Masters Runner: Part 1 - What Changes?

Unfortunately, runners don’t get better with age. This strikes a heavy blow to the “the more you practice the better you get” mentality, because it’s pretty clear that physiology takes over at a certain point. We know that performance declines, but what exactly happens as age increases? First, let’s define what the “Masters” runner is:

Age 30+: USATF track

Age 35+: World Masters Athletics

Age 40+: USATF road running

Not only is that not “old” (according to most of us near or past those age ranges), but the definition isn’t really even standardized. Interestingly, a lot of studies don’t exactly categorize Masters level and younger runners the same way, though the difference between a 35 year old and 102 year old Masters runner is going to be pretty large. Before going into what those differences are, it should be noted that most studies categorize “young” runners to be <30, “Masters” runners to be between 40-60, and “older” runners to be >60. So what actually changes?

VO2max and cardiovascular function:

This seems to be the most influential category on running performance as a runner ages. Primarily, a decline in VO2max (maximal rate of oxygen consumption during exercise) is the culprit. A slower rate leads to less relative energy production which leads to the inability to sustain a certain work bout, decreasing running performance. Maximal heart rate and cardiac output also decline steadily with age, contributing to increased effort at a given maximal pace. Along with the lower maximal-effort conditions, we also see relative changes at sub-maximal (lactate threshold) paces; VO2, heart rate, and velocity at lactate threshold all decrease with aging, indicating a greater absolute effort.

Muscle strength and power:

Unsurprisingly, muscle strength and power (force production in short periods of time) declines steadily with aging, contributing to decreased running speeds. While continuing to run as we age reduces the strength decline, running alone isn’t enough to prevent it. One of the main reasons we see a decline in muscle strength is decreased muscle mass or atrophy with aging. Muscles with smaller cross-sectional area are unable to produce as much maximal force.

Muscle power is a separate force-related category that we also see declining with age, likely as a result of a lower percentage of fast-twitch (type II) muscle fibers. Lower maximal strength and more difficulty producing force quickly results in steep declines in muscle power, seen mostly at the ankle in Masters runners. There is some data to suggest that older runners training at higher relative intensities may see fewer declines in power, specifically at the ankle, but there is limited evidence on how to best attenuate these declines (although a few ideas have been proposed).

Running economy:

An important predictor of running performance, this has actually been shown a number of times to NOT be correlated with aging. This means that the cost of running at a given pace is essentially the same, there are just a number of other reasons why it’s harder to maintain a given pace at an older age (see VO2max and strength/power).

Some other biomechanics:

There are a handful of other biomechanical variables we see changing with the Masters runner, most of which are likely results of what’s already been discussed. Decreased step length is fairly consistent across the board with aging and correlates strongly with decreased velocity. Step length and step frequency (cadence) have an inverse relationship, though, and increases in step frequency tend to reduce some (but not all) of this decreased velocity.

In addition to reduced step length per stride, ground reaction forces during each step are lower in the Masters runner; both vertical force and propulsion are decreased, very much relating back to the decreased ankle power mentioned above. This is consistent with what we know about the demand on the calf for both vertical and horizontal propulsion during running.

“Stiffness” in biomechanics is a property that explains the resistance of movement to an external force. The more stiff something like a tendon is, the less relative excursion occurs within a loading cycle. It’s debatable what the optimal amount of stiffness is for performance and for injury-risk reduction (probably two different answers), but one thing we know is that in the Masters runner, tendon and lower limb stiffness actually decreases. This seems counterintuitive, because we think of becoming less flexible through the aging process (which is true), but the shock attenuation strategies with aging runners tend to incorporate more overall compliance (ease of deformation). Increasing tendon stiffness is a strategy to absorb and release energy in a passive structure, resulting in more efficient movement. Decreased tendon and lower limb stiffness in the Masters runner is likely a large contributor to declines in muscle power and subsequent increased effort at higher velocities.

Mental attitude towards aging and sport:

It seems fairly obvious to state, but most individuals take on more responsibilities and have less free time as they age. There are clear outliers here, but to compare the amount of time a high school runner can train with that of a Masters runner with a full-time job and family, it’s pretty significant. Running can’t be the primary focus for most individuals as they age, so it’s natural that a decline in performance comes along; with less time available to train and recover under minimally stressful conditions, performance can’t be maintained.

The attitudes and beliefs of the aging runner are also important to note here. Is the Masters runner so competitive that they want to continue winning their age group? Or is their motivation to train stifled by seeing performance gradually decrease? The Masters runner that continues to train at a high volume and intensity can slow the rate of decline, but it requires the belief that putting in the effort is worthwhile.

The last component in this category that I see quite a bit is fear of injury. In a sport where overuse injury rates are pretty out of control, it’s not often that a Masters runner has never had a time-loss injury. If the aging runner deems their training habits too “risky” to maintain long term, running volume and intensity are voluntarily decreased and the aforementioned running performance decreases.

In Part 2 we’ll look at injuries because that’s an entire discussion on its own.

Questions? Comments? 

Dr. Jason Tuori, PT, DPT, CSCS

References/cool running readings:

1. Tanaka H, Seals DR. Endurance exercise performance in Masters athletes: age-associated changes and underlying physiological mechanisms. J Physiol (Lond). 2008;586(1):55-63.
2. Devita P, Fellin RE, Seay JF, Ip E, Stavro N, Messier SP. The Relationships between Age and Running Biomechanics. Med Sci Sports Exerc. 2016;48(1):98-106.
3. Willy RW, Paquette MR. The Physiology and Biomechanics of the Master Runner. Sports Med Arthrosc Rev. 2019;27(1):15-21.
4. Quinn TJ, Manley MJ, Aziz J, Padham JL, Mackenzie AM. Aging and factors related to running economy. J Strength Cond Res. 2011;25(11):2971-9.
5. Paquette MR, Devita P, Williams DSB. Biomechanical Implications of Training Volume and Intensity in Aging Runners. Med Sci Sports Exerc. 2018;50(3):510-515.
6. Fukuchi RK, Stefanyshyn DJ, Stirling L, Duarte M, Ferber R. Flexibility, muscle strength and running biomechanical adaptations in older runners. Clin Biomech (Bristol, Avon). 2014;29(3):304-10.