BRINGING SCIENCE TO TREATMENT

Physiological and biomechanical changes in the aging runner

The New Year often brings resolutions to be more active. Runners who gather renewed resolve to hit the trail may register for an upcoming race to inspire their training. Statistics show that the age of those participating in races is increasing dramatically. From 1980 – 2000, the New York City Marathon showed an almost 200% increase in runners over the age of 40 years1. When researchers drilled down into the specific age groups, they found that the over 60-year-old brackets quadrupled their participants during that time span1.

Researchers attribute the increase in numbers to two likely causes. The first is that aging runners chose to maintain a running program throughout their lifespan. The second reason being that some people decide to start running later in life. Either way, while research and resources typically focus on young elite athletes, the reality is that the runner coming to seek your services will likely be over 40.

Physiology of aging

As the body ages, it undergoes changes in function. One change anyone with an aerobic training background knows immediately is the decrease in maximal heart rate recommended during aerobic activity (220 – age = Max Heart Rate (MHR)).  This in turn lowers overall cardiac output (Heart Rate (HR) x stroke volume) and the body’s ability to take in and utilize oxygen during exercise (basic calculation for VO2max = 15.3 x (MHR/Resting HR). There’s no getting around it, aging decreases endurance. Not only that, the lower VO2 max associated with aging is a known risk factor for chronic diseases1. Therefore, running later in life is an effective strategy to decrease one’s risk of declining health due to age1.

Better with age

Knowing that the aging process takes a toll on the cardiac system and therefore, endurance, how does one explain athletes who perform better as they age? The key may be their ability to maintain or improve their running economy. Running economy (RE) is the rate of oxygen consumed during submaximal running2.  Good RE requires less energy and therefore less oxygen. Unlike VO2max, age doesn’t seem to effect RE.

For the aging athlete with less than optimal RE, perceived effort increases as VO2max decreases. Due to the rise in exertion required, runners may lower their training volume or intensity. With a drop in training stimulus, VO2max suffers a further decline. Therefore, the consequential easing off of training from having to work harder magnifies the changes already taking place in the cardiovascular system of the aging athlete.

Holding back the years

Though sparse, longitudinal studies of elite runners show that runners who train at more intense thresholds throughout their life span show less decrease in VO2max over time than those who’s training levels off or declines1. Training to increase VO2max requires near maximal effort over a sustained period of several minutes. Repeated training allows adaptation of the cardiovascular system as it becomes more efficient. While nothing can turn back the clock, training, even in Master athletes, can improve VO2max and stall the effects of aging. Therefore, encourage older runners to train at volumes and intensities at the limits of their abilities.

Reference

  1. Sports Med Arthrosc Rev. 2019 March;27(1):15-21
  2. Sports Med. 2004;34(7):465-85

 

 

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