It sure feels that way, but science doesn’t necessarily agree.
As a 41-year-old, I can attest that I don’t bounce back from tough workouts as quickly as I used to. It sometimes feels like there’s no bounce left at all – just the prolonged feeling that some trickster has painted the soles of my shoes with glue. Most of my contemporaries report the same thing.
Of course, it’s not just the passage of decades that distinguishes the current me from my 21-year-old counterpart. I’m a lot busier these days, so I train a lot less – less mileage, less intensity, less of pretty much everything. My non-training hours are mostly spent sitting (or, when I remember, standing) at a desk in front of a computer screen instead of, say, playing pick-up basketball or exploring on my bike. I’m weaker than I used to be.
All of this creates a familiar chicken-and-egg question. Do I recover more slowly these days because I’m old, which prevents me from training as hard as I used to and consequently makes me less fit? Or do I recover more slowly simply because I don’t train the way I used to, which in turn makes me feel old?
It’s pretty hard to answer this question definitively, because people live the lives they live – you can’t randomise volunteers to be lazy or active for several decades to see what happens. Ultimately, of course, ageing isn’t just an illusion, and there’s pretty good evidence that by the time you’re in your 60s many things – including how quickly you recover from a hard workout – have changed.
But what about in your 40s, a time when many people start to feel older but evidence of physiological decline is more equivocal? That’s what a new study in the Journal of Strength and Conditioning Research, from researchers at the University of Central Florida, US, led by Jay Hoffman, investigates.
The study compared nine men with an average age of 22 to ten men with an average age of 47. A crucial detail is that everyone in the study had to be “recreationally resistance trained”, engaging in resistance training over the previous six months while meeting standard guidelines of at least 150 minutes of exercise per week. That doesn’t guarantee that the two groups were equally fit and active, but at least we’re not comparing young athletes to older couch-potatoes.
The volunteers all did a “high-volume isokinetic resistance exercise” workout, which involved eight sets of ten repetitions using machines where they straightened and then flexed their knee repeatedly against a resistance. Their leg strength was assessed before and after the test, and then reassessed a few more times until 48 hours after the workout, along with blood tests to monitor muscle damage and inflammation (which is a key part of the muscle-repair process). While the workout isn’t running (and is quite different from typical strength-training protocols too), the basic pathways of muscle damage, repair, and recovery are thought to be similar across exercise types.
The results are pretty simple to sum up: there were no differences between the two groups. The younger group was stronger to start out with, but the relative loss and recovery of strength was the same in both groups. Markers of stress and inflammation also followed the same trajectory in both young and old; so did subjective reports of pain and soreness.
Here’s some sample data, showing levels of interleukin-6, a marker of inflammation that “facilitates communication for the mobilisation, proliferation, and differentiation of immune cells to the site of tissue damage.” The young folks are the black bars, middle-aged are the white bars. You can see increases starting after 30 minutes (30P) and persisting 48 hours later, but no significant differences between the groups.
If you squint, might you imagine that the inflammatory response in the older group is a little less pronounced? If this study had 1000 subjects in each group, would that difference become statistically significant? It’s impossible to say for sure – but even if it did, you’d still be left with a pretty subtle difference. In other words, there’s no smoking gun here to explain the effects of ageing. Score a point for the “we feel old because we act old, not the other way around” school of thought.
In practice, the distinction probably doesn’t matter too much. Whether I’m fighting biology or lifestyle, the end result is that I need get out more and work harder – like I used to.
And on that note, next time I’m dragging around feeling beat after a hard workout, I need to remind myself that it wasn’t all smiles and rainbows in my 20s, either. Flip through my training logs from that period, and you see tons of entries tagged with comments like, “VERY tired. Legs heavy. Slow.” That’s not ageing, it’s simply training – and later, when you rest up and it all comes together, it makes it feel all the sweeter.