It’s hard not be somewhat aware of the effects of aging on our running – it shows in our race and training times! We slow down and at root we grudgingly accept that. But to be honest, my understanding of all the elements driving this was rather vague. Aside from injuries and accidents I was holding up pretty well. Something has changed, however, in the past couple years. The age grade tables suggest my per mile 5K pace should have increased a total of 11 seconds over the past three years. But I’m seeing an increase of 30-40 seconds! So what’s up?
For one, I’ve spent much of the last year studying exercise physiology in preparation to return to grad school for research in aging and performance. I’ve been a sponge – absorbing anything I can find about why we slow down as we age. Most of the constraints are explained by impacts on our muscles, bones, cardiovascular, and breathing systems. A somewhat comprehensive list I’ve compiled includes:
- Changes in muscular and connective tissue quantity and quality
- Decline in the number of neurons and a slowing of how fast nerve impulses stimulate our muscles
- Reduced key hormonal production such as growth hormone
- Retardation of pulmonary ventilation and gas exchange
- Declining cardiovascular function resulting in reduced VO2max
- Changes in bones, joints, and overall body composition
- Behavioral aspects affecting exercise adherence
So how does this knowledge play out? No doubt I’m both consciously and subconsciously carrying this stuff with me as I attempt to motor around the track, thinking:
(1) My maximum heart rate has decreased, which means I’m pumping less oxygenated blood to my muscles;
(2) The muscles getting this blood are fewer – both Type I and especially Type II muscle fibers – and they are all smaller;
(3) The contractile mechanism in muscles allowing for movement, technically called the “actin-myosin cross bridge” gets more sticky over time creating internal friction, detracting from useable muscular output;
(4) My joints, tendons, and ligaments are either less tensile or stiffer and certainly less flexible, putting a drag on my range of motion and stride length;
(5) The air sacs in my lungs are less pliable and I can’t help but notice it’s harder to breathe while racing or running intervals on the track.
So, I conclude, as I beg my GPS to show faster splits, that for all these reasons I am of course running slower while having to work as hard or even harder than ever!
On top of everything, on these hot summer days I’m aware the declined ability of our aging bodies to vent heat – I feel the heat and humidity in a way I hadn’t previously noticed.
So I ask myself, is all this new knowledge an added burden, as if I’ve gained 10 pounds (which I have not!) that I now have to lug around? Time will tell, as it usually does, what’s real and what is imagination. Meanwhile, I can’t put the genie back in the bottle – it’s out there and I have to live with it. The upside, I suppose, is that if I’m going to study aging and performance, I can include myself as a subject. I can be part of the experiment and try to learn something every day as I lace ‘em up and give it a go. Not exactly what I had in mind when I started this adventure. Maybe ignorance IS bliss!