It is usually stated that maximum aerobic capacity (VO2Max) declines with age at a rate of about 10% per decade in sedentary people, but that those who continue to do fitness training will only lose this capacity at about 5% per decade. A typical study upon which this rule of thumb is based is ref. 1. This is one of the reasons for the maxim “use it or lose it”. It appears to be “really use it so you lose it more slowly”. But it’s important because the difference between 5% and 10% is huge for quality of life. Activities of daily living like being able to go up stairs become very difficult or impossible if VO2Max goes below about 20. This can happen by the time you are about 70 or 80 if sedentary, but can be delayed until more than 100 years of age if you keep training.
Another important factor is that it has been shown that aerobic capacity can be regained significantly over a few months of training in older people who have previously been sedentary (Ref 2). So if you get to a certain age, and realize you’re slowing down (“Why am I starting to get winded walking over to the mailbox?”), you can readily turn the clock back a few decades, fitness-wise, by getting serious about training to get in shape.
But a 2022 meta-analysis  looked at the data from a lot of previous studies to reexamine this matter. I learned of this from Alex Hutchinson’s “Sweat Science” in Outside Magazine (there may be a pay wall on the link but they usually allow you a few free peeks at articles). The most important finding is that even serious athletes who continue training, tend to reduce their training volume (number of hours per week) over time. Among those who keep up their volume, the rate of loss in VO2Max is even smaller, more like 2.5% per decade. Alex pointed out that coach Alan Couzens, based on data from his own athletes, goes further to suggest that a decline in fitness may be avoided entirely if we increase our training volume as we age. Coach Couzens came up with the rule of thumb that we have to train our age, in hours, each month, to achieve this. So when you are 80 you just have to train 80 hours per month, or 20 hours a week. This is a lot, obviously, and well beyond the 150 minutes (2 1/2 hours) a week of training typically recommended by health authorities.
But this may actually be feasible for some of us who are retired and for whom fitness is our hobby. By coincidence, I currently do train for about 2 1/2 hours per day on average, because I enjoy it, which exactly meets Couzens’ rule. If I just bump it up a bit each year, and by the time I’m 80 I do about 3 hours per day, does that mean I’ll lose no fitness at all? I’ll be excited to find out 10 years from now.
All of this has oversimplified the issue by only considering training volume and not intensity. Various methods exist for improving VO2MAX significantly with lower volume and higher intensity training. Probably the most famous is the Tabata protocol, which takes only four minutes total but involves 8 rounds of 20 seconds of sprinting with only 10 seconds of recovery in between. Time-efficient, but very tough! I would speculate that those who train with considerably less volume, but keep their intensity high enough, could also fight off the decline in fitness with age quite well. I have also seen the opposite effect. There are cyclists in the club I ride with that have kept their training volume quite high for decades, but their intensity has decreased over time (they’ve either gotten slower or are doing fewer climbs). So I suspect keeping volume high and continuing to do some high-intensity work are both important to prevent getting slower.
What about for those of us for which fitness is not a hobby and are not particularly excited at the prospect of training for hours per day? I would say just try to get the public health recommendation of 2 1/2 hours per week of activity. And throw in some higher-intensity stuff like walking up stairs or cycling up hills at least once a week (other aspects of fitness like resistance training and balance training are also important). Your fitness may decline some over time, but a lot less than for a sedentary person, and you’ll still be able to do activities of daily living at 100. Not a bad result.
April 19, 2023April 17, 2023