For the last 30-some years of the 68 I've been on the planet my training has been pretty consistent. There have been the usual breaks of a week or two due to illness or other normal lifestyle matters. The biggest gap was back in 1995 when I was diagnosed with a virus in my heart and was told to stop exercising until the symptoms went away. That took seven months. Even last year when I fractured my pelvis in a crash I missed 20 days of riding as I rode an indoor trainer for three weeks (with the broken side of the hip hanging over the edge of the saddle). Maybe that means I'm OCD. I suspect most serious athletes are.
My point here is not to try to convince you that I'm some sort of freak of nature, but rather to make a point about my training consistency before I launch into a description of how I, as an old guy, trains. I'm often asked about that by other aging athletes. What I'm about to describe is, to some extent, a result of several decades of regular exercise. It may not apply directly to you.
When it comes to determining how one should train, perhaps the most important elements are how long and how stressful the previous training has been. Consistency (as in weeks, months and years) in both of these areas has more to do with how much and how hard you can exercise with advancing age than any other elements. The commonly accepted theory is that we each have a genetic ceiling for exercise and performance. We typically refer to this as our "potential." The theory says that we can only maintain or slow the rate at which our potential declines over time. The theory also says it won't increase. If you were inactive for many years earlier in life, and especially if you are new to serious training only recently, then you can assume that your capacity to manage a training load has decreased considerably.
Again, I'm only telling you this to set the stage for what follows. This is not intended to be a description of how every 50-, 60,- or 70-something athlete should workout. I know many who do considerably more than I do, and also many who do less. There is no single, right way to train in terms of workout frequency, duration and intensity as we get older; nor is there a formula for determining what one's training regimen should be at any stage of life. There are as many different ways to train as there are athletes who want to train. So if you ask me to tell you how to train given one or two lifestyle variables, previous performances, or goals, please be aware that I'd only be guessing. For that reason I never tell athletes who I know little about exactly what they should do in training. Even when I coach someone and get to know them quite well, there is still a lot of head scratching that goes on when it's time to write a training plan for them. So I really can't tell you, who I don't know, what you should do. It would just be a wild guess on my part.
So, given all of these disclaimers, below is a general outline of how I train based on seasonal periodization. I'm a road cyclist and race only a few times each year with a preference for hill climbs and time trials. As a runner, triathlete, mountain biker, swimmer, or other type of endurance athlete you need to keep this in mind as the sport one participates in has a lot to do with how to train. For example, the anaerobic endurance workouts you'll see listed below are necessary for a sport like road cycling in which two-minute episodes of very intense activity often determine the race outcome. That's seldom the case for the other sports listed above.
My workouts are planned based on Training Stress Score
(TSS). If you don't use TrainingPeaks or WKO+ software then that
probably doesn't mean anything to you. But in a nutshell, it's a method for
quantifying the workload of a workout based on its duration and intensity.
Duration (time) is easy. Intensity comes from either a power meter (bike), a
GPS device (running), or a heart rate monitor (any sport) and is expressed as a
percentage of one's Functional Threshold Power/Pace/Pulse (FTP). FTP represents a hard effort and is done right at the start of your "redline." Percentages of FTP, both above and below, are called the Intensity Factor (IF). Although the software doesn't do it
this way, one way to use IF is to think of FTP as an IF of 10. That would be a
very hard, max effort that you maintain for an hour. Conversely, if you workout at half of that intensity--an
IF of 5--it would be a relatively easy session (or portion thereof). You could also do an interval, for example, at an IF above 10 but you certainly couldn't hold it for an hour.
An easy way to determine TSS is to square the IF and multiply by the number of hours. So a 2-hour workout at an IF of 5 would be a TSS of 50 (5 x 5 = 25, 25 x 2 = 50). Again, that's a pretty easy workout. (All of this is explained in much greater detail with many examples in my newest book, The Power Meter Handbook.)
So given an understanding of that, here are the basic workouts I do, regardless of the training period, based on TSS:
TSS 50. This is a 2-hour ride done at IF 5. These are done year round (base and build periods).
TSS 100. For me this is usually a 2-hour workout averaging an IF of around 7 (7 x 7 = 49, 49 x 2 = 98). An average IF of 7 over 2 hours is typically either the result of doing a long zone 2 steady state ride (base period) or intervals at zone 4 or higher ("muscular" or "anaerobic" endurance training) with recoveries in zone 1 plus a long warm-up and cool down (build period). Be sure to note that the build period 7 IF is an average for the entire workout, part of which was very hard and part very easy.
TSS 150. This is much the same as above only it is a 3-hour session. It's more likely to be a hard group ride or a hard effort in the mountains (build period) than intervals. I do one of these every 6 to 8 days. (More on why the frequency varies is explained shortly.)
TSS 200. Again, the same as above only a 4-hour workout in zone 2 (base) or with a fast group or a hard mountain ride or some unique combination of many different portions (build). I do these infrequently, but once a year I'll do a few days of these back to back in a camp environment to boost fitness. In my Training Bible books I call this "crash" training.
Now back to being old. The big issue for the aging athlete is recovery. That's always my major concern. I use something called "recovery on demand." That means when I feel tired I may do two or three TSS 50 workouts back to back or take a day off followed by a TSS 50. This can happen at any time. That's why it's "on demand." I can sometimes predict it a day in advance, but not always. Some days I start my ride and decide after a few minutes that it needs to be a TSS 50. Totally unplanned.
Without considering recovery on demand, my typical TSS schedule is something like this, regardless of base or build period:
TSS 50 - 100 - 50 - 100 - 50 - 150 repeat
This pattern is repeated until I feel the need to recover for more than one day. Then I'll do two TSS 50 sessions back to back, or possibly even three if really wasted. Or a TSS 50 and a day off (TSS 0). This is why I said above that I do a TSS 150 every 6 to 8 days. It just depends on how I am recovering.
I'm sure if I was younger I could do more TSS 100 workouts back to back before a 50. And probably a lot more 150s and 200s. And certainly even much higher TSS workouts. That's all rare except in a crash period which I do very seldom--as in once a year. A crash period is always followed by a lot of recovery, perhaps as much as a week of TSS 50s.
I wish I could tell every aging athlete who reads this how to train, how hard the workouts should be, how long they should be, how often they should recover, what the recovery should be like, and more. But I can't. It's simply not possible. I'd have to coach you for several weeks before I could answer all of those question. So, please realize that if you ask me how you should design your training given a few variables (or even a page full of them) that I really can't do it. The best thing I can do for you is to have you read one of my Training Bible books. They walk the self-coached athlete through all of these many, many details. There is also a section in these books with more details for aging athletes.