Article: Invited Review: Dynamic exercise performance in Masters athletes: insight into the effects of primary human aging on physiological functional capacity. Tanaka H, Seals DR. J Appl Physiol. 2003 Nov;95(5):2152-62.

Background: I would like to provide a little background prior to discussing the article for this edition of Jon's Journal. I am currently doing research at UT Southwestern Medical Centre at Dallas in the area of obesity/aging and cardiovascular disease. One of the most frequently cited studies performed here was called the "Dallas Bed Rest Study" where in 1966 six men underwent 3 weeks of complete bed rest and 6 months of training to determine the effects of severe deconditionning and training on cardiovascular function and fitness. These subjects were studied 30 years later to evaluate the effects of aging on the same parameters. Amazingly 3 weeks of sloth was more detrimental to your health than 30 years of regular aging! Since that time a major research focus here and in other labs across the world has been to document the beneficial effects of aging on cardiovascular health.

Now that I am working with these scientists and trying to slow the aging process myself, I thought I would share some insight into the cardiovascular adaptations that occur with regular aging, how exercise plays a role in keeping you healthy and how age can affect your training and recovery. What happens to our bodies as we age? For most of you who are coming back to endurance sport after some time off you will notice a few things:

1. You are slower.
2. You don't recover from training like you used to.
3. Your heart rates are not what they used to be.

Studies in male and female endurance athletes show that endurance performance increases with training in humans to 35 years of age, thereafter is slowly declines slowly until the age of ~50, and steeply after that. These studies are cross sectional in nature and may simply reflect a social phenomenon that is unrelated to human biology however the trends are very interesting. Humans have the ability to maintain endurance performance for decades despite significant biological changes to the cardiovascular system that inhibit exercise performance. The reason for this reduced performance is associated with an age-related decline in V_O2^max (aerobic power) that can be attributed to a progressive reduction in maximal heart rate at a rate of ~ 10 beats/decade. Interestingly, the decline in fitness occurs at a rate of ~10%/decade in males and females, regardless of their training status. As such, no matter how hard you train, natural biology is working against you slowly taking away your fitness. Aging is also associated with a reduced lactate threshold, or the percentage V_O2^max of  that you can sustain for a prolonged period. Finally, it is possible that age is associated with a transformation of muscle fiber types from the preferred fast oxidative to the less preferred easily fatigable fast-twitch fibers. Taken together you have to understand that in some cases just simply maintaining your endurance performance throughout the middle-age years can be regarded as a successful season.

Amazingly, the degree of trainability, or the relative improvement in fitness following a chronic exercise training program is not that much different in younger and older sedentary individuals. Although it may take longer for an older athlete to recover from a bout of training, improvements of ~15-25% in V_O2^max are commonly reported in young and old previously sedentary men and women. So if you are not currently training and think you may be too old to get started, previously sedentary individuals have the ability to adapt, regardless of their age. IN fact, Ed Whitlock,at the ripe young age of 72 ran an unfathomable 2:54 marathon at the ScotiaBank Toronto Waterfront Marathon this September. This and his 1:22 half marathon at the age of 70 are both age class world records www.ranelagh-harriers.com/edwhitlock.html .

How will affect my training? Firstly, studies in older men and women universally reveal that exercise training reduces the age-related declines in cardiovascular health. (i.e. The more you train, the healthier you are and lower your risk for chronic disease). Second, sedentary lifestyle has a more profound negative effect on the cardiovascular system than regular aging. So get out there and get in a run or a ride as often as possible to battle the negative effects of "sloth" on your health. Finally, and most importantly, have your fitness tested periodically to get an idea of how the aging process is affecting your maximal heart rate. If you use heart rate to gauge your training, it is essential to be tested throughout the year to make sure your training intensities have not changed.

Coming up: Should my training program change as I get older?