What happens to use biologically that slows us down as we age?

it has nothing to do with slowing down, it's more a matter of losing interest. The world is no longer new and exciting.

Everyone who makes it to old age will stop caring about anything but walking their dog and feeding ducks. They know nothing really matters.

I heard heat exhaustion can cause long lasting effects. Like after you have had it, then it comes on quicker the subsequent incident and so forth in a compounding effect. This is from a survival thing built into our bodies. Over time it can prevent one from working as hard and long as before. That is just one thing and is not going to be across the board but it's there.

Then there's injuries and nerve damage especially in the feet that can have a change to your gait and efficiency.

Best prevention or reversing the effects of aging is keeping mobility and muscle mass.

Hormonal changes can also slow a runner down.

Or a higher volume of stress or lack of focus in consistency of training.

Chalk it up to the gestault effect; the sum is greater than the parts.

Our telomeres shorten

World class Marathon running is a very short career. It is rare for a runner to dominate that distance for more than a few years.

It’s the nature of the sport. What it does to your body and the commitment needed to stay on top

Stephen Seiler wrote a good summary of aging and cardiovascular function that used to be available online. I just checked the link but it is dead. I have it but it is apparently copyrighted.

Just a few quotes:

Decline in Maximal Heart Rate

"There is no strong evidence to suggest that training influences the decline in maximal heart rate. This reduction appears to be due to alterations in the cardiac electrical conduction system (SA node and Bundle of His), as well as down regulation of beta-1 receptors, which decreases the heart's sensitivity to catecholamine stimulation"

Decline in Maximal Stroke Volume

"Ultimately, maximal stroke volume appears to decrease due to a 1) decrease in training volume and 2) an increase in peripheral resistance."

Increased Peripheral Resistance

"In our youth, this system of arteries is quite flexible or compliant. This is important for the performance of the heart. Compliant vessel walls stretch when blood is pumped through them, lowering the resistance that the heart must overcome to eject it volume of blood each beat. As we age, these vessels lose their elasticity. Consequently, resting blood pressure and blood pressure during exercise slowly increase as we age. Continued training appears to reduce this aging effect, but does not eliminate it. Increased peripheral resistance results in a decrease in maximal blood flow to working muscles."

Here is a video where he discusses why we slow down.

The list of things that matter is really long. Here are the seven that hit me hardest between about 40 and 50 (of course for others the year will vary):

• muscular changes due to injuries (especially my hamstrings)
• loss of muscle mass (relative to total weight)
  
• ligament and tendon injuries that heal (but don't heal 100%)
• reduced testosterone that impacts body composition (dad bod) and muscular strength
• loss of flexibility which results in shorten stride
  
• slower recovery time which results in the need for more down-time between hard training sessions
• a series of serious but manageable injuries such as plantar fasciitis, a sports hernia, thrown out backs, stiff necks, pulled hamstrings, twisted ankles, calf tears, etc.

The juice wore off. Testing is getting stricter, he doesn't have a good source and is having to do it clean using store-bought supplements.

I'm about to turn 65. I have never been great, I was locally good for years. Ran about 50-65 mpw for about 40 years.

In my 50's I found that:

1. The same perceived effort was much slower than it was when I was younger.

2. My body just couldn't handle the training load.

3. It takes me much longer to recover from workouts and races.

4. There is some lack in motivation but I can easily overcome it.

5. According to my doctor (based on yearly blood work) I am as healthy as a healthy man 20-25 years younger than I am.

6. Those very unscientific lactate threshold test all come out the same (about 44-46) and that is what is considered "normal" for someone 20-25 years younger than I am.

7. The bottom line is that when I was in my 20's to 40's an easy 6 miles was at about 6:00-6:20 pr mile. Now, 8:30-9:00 (unless I run very early in the morning then it's 9:00-9:30.

8. In my mind and heart I can still run as fast as in my youth. My body says no. = (

Simple. Oxidation.

Telomere shortening, genomic instability, epigenetic modification, mitochondrial dysfunction, loss of proteostasis, dysregulated nutrient sensing, stem cell exhaustion, cellular senescence, altered cellular communication. All lead to systemic inflammation. Mitochondrial dysfunction being the primary factor leading to ROS (reactive oxygen species)

Decline in ATP production, increase in ROS production, and decline in antioxidant defense = oxidation = severe damage to cells, organelle membranes, DNA lipids and proteins.

Ironically, exercise keeps us healthy but it also promotes oxidation.

A "funny" story about perceived effort. A couple years ago I was in our Turkey Trot, shortly after the start, an old friend came up beside me. We were back, maybe top 150 out of 600.

I said- What's sad is that 30 years ago we'd be leading this race.

He said- What sucks is that the effort felt the same.

It's sad, but it's life.

I'm about to turn 61. 40 years ago, I was a sprinter with a sub 10.4 PB. While we did some distance for conditioning, I never liked running long distances. Fast forward to now where I have taken up hobby jogging. I also run 5K races and have a PB of 9:12 mins per mile avg pace. Some days, no amount of telling my legs to pick up the pace work. While I think I am running quite fast, I realize I am not, when a man or woman runs pass me pushing their child in a pram. I go hobby jogging early mornings at least 3 times per week. 4 times is pushing it. Depending on my feel, I run at an average pace of between 11:15 mins/per mile - 12:28mins/per mile. As youngsters blow by me , I have a few picoseconds of envy then I become thankful that I am still able to go for a jog.

There are more aches now.

Takes longer to recover now

I lose aerobic capability a lot quicker now.

While I can still remember correct running mechanics training from my youth, there are times I employ wasted body movements while jogging. I know I'm doing this, but correcting it is now no longer as important as it would have been when I was a sprinter.

Time catches up on us all.

I go for a jog; challenge myself and do my best to always enjoy no matter how slow or fast I run.

All these points can be worked, by food, another life style and preventatively more care for the body. Less use of medicines also helps.

Two things that have helped me stay in the game running wise that I would encourage others to try, if they don't already are the following.

Run with a running group/club/team regularly and preferably at least once per week. This helps keep you competitive and up on your game, so to speak.

Second, try to work in at least a very few races each year even if you aren't competitive, just because it makes you feel that you are working towards something rather than just going through the motions.

Sounds like you have solved the problem of aging. Is the Nobel committee aware of your research?

Nope, good food, lifestyle and taking care of your body does only so much. And then there are genetics as well.

As a 57 year old runner, this describes my situation perfectly.

I have found that your mind finally comes to grips with the fact that you aren’t going to be getting any PRs. No matter what distance or how much training you do. So you stop chasing speed records. And you are cool with that.

But the most depressing realization it to watch your easy paces get slower and slower. And going out for easy runs that are supposed to be easy but aren’t.

like you said. That’s life.

If you were right, then the masters records would be as fast as the world records and we would be immortal. Something has to give. We are all aging.

Where you are correct, of course, is that if we take good care of ourselves, we can delay this process (though never stop it). I think I have been pretty good about how I treated my body but even the simple fact of running 80,000 miles (so far), has done a lot of damage that sleep, hydration, and good nutrition hasn't been able to prevent. A torn achilles or Plantar Faciitis doesn't care about your sleep habits, for example.

You can minimize and delay the impact of some of these to a certain extent by modifying your lifestyle, diet, supplemental activity, etc.

But that requires an investment of additional non-running time and energy that does not provide the same benefits and results that running does. You can get to a point where you are spending more time and energy working at various non-running things just to be able to run (and run more slowly, with more effort, risk and pain than before).

Everyone is different and everyone ages differently, but Father Time always wins in the end.

Pulmonary function peaks around age 25 then starts to slowly decline, but there are so many biological factors that it's probably impossible to pin it down to just one.