Running weight loss and science'ish

[DominicJ]

Since January, I have lost a lot of weight, and I have improved my 5k time
If we ignore my initial really poor 5k times, they have 'improved' by roughly the same amount

Using force = mass * acceleration

With mass being my weight in kg
Acceleration being the treadmills efforts to propel me in to the wall
I get a force that's consistently 108 somethings, in a range of about 5%, explainable by shoddy weight recording

Have I stumbled on to something? Something that makes you all go, well duh
Or is my running training simply ineffective?

Any thoughts?
It seems creepy

[SunsetRunner]

Yes, less body mass, more muscle fibre, and high VO2 max. makes a big difference,

but it all depends on who your parents are (namely the genetics that you've inherited).

Some people have more "fast twitch" and some have more "slow twitch" muscle fibre.

The first, will (assuming effective training and nutrition), give a faster sprint to 5 km. time,

and the second (assuming effective training and nutrition) give faster 10 km. - marathon time.

However, genetics are always limiting factors, no matter how much you train there's a limit.

People on a high fat/cholesterol/protein diet, will never have sufficient muscle glycogen

to fuel the muscles to fast sustained running. High complex carbohydrates are needed.

[Heybales]

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@DominicJ wrote:
Since January, I have lost a lot of weight, and I have improved my 5k time
If we ignore my initial really poor 5k times, they have 'improved' by roughly the same amount

Using force = mass * acceleration

With mass being my weight in kg
Acceleration being the treadmills efforts to propel me in to the wall
I get a force that's consistently 108 somethings, in a range of about 5%, explainable by shoddy weight recording

Have I stumbled on to something? Something that makes you all go, well duh
Or is my running training simply ineffective?

Any thoughts?
It seems creepy

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I would actually expect better.

Let's say after a couple weeks getting the weight on the bar right, you could squat 195 lbs for 3 x 10 reps at the beginning of the weight loss journey.

Then you lost 40 lbs after some time.

And your squat went up to 225 for 3 x 10 reps.

Did you improve?

No, you only added 30 lbs to the bar, but lost 40 lbs from the body - which you are also squatting.

You got worse actually, lost strength.

Yes - you should be able to propel the body easier with less mass.

You should also be able to propel it easier from increased cardiovascular system improvements all by themselves.

And better form efficiency usually comes in to play too for an improvement just for that.

The latter 2 should cause improvements even if weight didn't go down.

Unless - you were already cardio fit, and good running form, just not for that weight.

In which case the improvements would come from mainly just weight loss.

[DominicJ]

Guess I better start trying to improve my running then.
I'd quite enjoyed my method of brute force improvement.

[cyronius]

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@DominicJ wrote:

Using force = mass * acceleration

With mass being my weight in kg
Acceleration being the treadmills efforts to propel me in to the wall

---

Acceleration is the rate of change of your velocity.  It's not useful a useful metric for a constant velocity treadmill...

Mass * velocity gives you momentum.  What this means is that you are maintaining a constant momentum as you run, as your increased velocity makes up for your reduced mass.  The fact that it's constant doesn't mean anything of note particularly though, though it is kinda cool 🙂

[Heybales]

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@DominicJ wrote:
Guess I better start trying to improve my running then.
I'd quite enjoyed my method of brute force improvement.

---

Well, you do strength training too - but that's the wrong muscle fiber for the running.

So just like weight lifting you can increase strength for a good while merely by improvements of form and complete CNS engagement without any additional muscle mass - you can make great improvements in running by same thing.

You are likely still in that process, usually cardio improvements do a fast jump, then a slow steady improvement.

Depending on how often you run, the CNS part (good form) could take awhile if not running that often.

I'll bet once you hit the constant running state in the program, performance will take another big jump if you keep at 3 x weekly slow pace.

Hey, at least you don't do a massive deficit.

There is a little research in to the fact that when you lose muscle mass in big deficit, it starts of course with least used. So you can do strength training and maintain type II fibers being used, and the type I in various places is what is lost, as shown in performance and biopsy.

[gerrymcd]

Its not surprising you are seeing a consistent 'number', it just means the net amount of energy you expend during your treadmill sessions is remaining constant.

The energy required to overcome the force exerted by the treadmill = half your mass multiplied by your velocity (ie speed) squared (approximating to the kinetic energy), ie

                0.5 mass x (velocity x velocity)

Consequently, even if you loose quite a few kilos you only have to increase your walking/running speed a little to keep burning energy at the same rate.  For example, if you run at 5 meters per second on the treadmill and you weight 75 kilos 

       0.5 x 75kg x (5 x 5)m/s

     = 937.5

if your weight drops from 75kg down to 70 kg

    0.5 x 70kg x (5 x 5) m/s

    = 875

Now if you increase your speed from 5m/s to 5.3 m/s

    0.5 x 70kg x (5.3 x5.3) 

   = 946.4

Ok, if you've got this far.......  it takes a relatively small increase in treadmill speed to compensate for your lost weight (your weight loss is halved in terms of the kinetic energy equation, whereas your increase in velocity is squared).  

[DominicJ]

Cyronius

Mechanics was a long time ago, (or were Vectors pure maths?) but.

My Velocity is 0, made up of a acceleration of x at 90* and acceleration of x at 270*

My force (the acceleration at 90*) matches that of the machine, so I stay still, but I only provide one of them, so staying still costs me energy.

But as I said, me and maths parted company a long time ago 🙂

Gerry

Thanks for the extra maths problems 🙂

I'll have a go at predicting what my 5k speed will when I get to target weight (140lb)

[cyronius]

Dominic, I'm half way through a Physics/Maths education degree 🙂

The machine itself doesn't have acceleration, because its velocity is constant.  The rate of change of velocity (acceleration) is 0.  Obviously the machine needs to use force to keep itself spinning, but that is the force to overcome friction and keep it in motion.  The net force is 0.

By the same token, a person moving at a constant velocity (whether it's 0 or a decent pace) has an acceleration of 0.  Whilst the person is applying force, this is used to negate the force of friction, leaving a net force of 0.