Jogging: why do I speed up after 40 minutes or so?

pwd

Started running for an hour 3 times a week.
I've noticed that at first I feel like I won't be able to go for very long at all. My calves and quads burn and I feel like I don;t have enough energy.
This worsens until about 20 minutes in. Then it goes away by about 30 minutes.
By 40 minutes I feel light on my feeet and can increase my speed substantially. One lap of the playing fields I'm running on takes less tahn 6m30s instead of about 7m30s.
Seems a bit odd. Does everybody get that?
I suspect part of it is to do with me feeling pretty tense generally at the start, to the point of my breath cathcing a bit, and my muscles being clenched to some extent.
After I run a bit I breathe deeper and more freely, and my muscles unclench, and I feel more coordinated.
Or is it just because I get endorphins released to make me less aware of the stress of running.
I check my pulse every now and then and it's not going above the recommneded rate, oir even that close to the limit most of the time.

edit: run for about an hour in total, and drink a litre of water with glucose and maltodextrin dissolved in it as I go.

Mr E

Maybe you're subconsciously aware that your workout is nearly finished, and adrenaline is kicking in to give you that extra push?

Mimikyu

This post has been deleted.

kazzer

You are developing your 'wind'. More specifically, this phenomena is called 'second wind'. Google.

Transform

Answered you own question really.
Don't think you need the sugar drink though - not necessary unless the run is over one hour.

pwd

kazzer wrote:

You are developing your 'wind'. More specifically, this phenomena is called 'second wind'. Google.

Cool thanks. That's interesting.
Different sources say it is casued by:

switching from glycogen to fat for energy
achieving optimal economy of movement
balancing the oxygen debt caused by lactic acid buildup
Increased blood flow into muscles
glucose depletion, when glucose is blocking the utilisation of lipids as an energy source.
diaphragm relaxing
burning the last of lactic acid in muscles
becoming properly warmed up
purely psychological causes

It's definitely not purely psychological. I don't imagine away bad pain in my legs, or imagine up the ability to sprint when I'm exhausted. I do warm up too. Fast walk to the park takes 15 or 20 minutes before i start.

i like this quote:

Second wind is only to a very small degree a question of breathing power. It is rather, the response of the vital forces to a will that refuses to heed their first grumbling protests - Stewart Edward White

Most sources state that most people don't experience this. All agree that it is achieved by pushing on when you're tired. Interestingly, one source published in 1907 says that most people do experience it, and a recent one says that people used to get it more often decades ago.

mrbungle

pwd wrote:

i like this quote:

Second wind is only to a very small degree a question of breathing power. It is rather, the response of the vital forces to a will that refuses to heed their first grumbling protests - Stewart Edward White

Most sources state that most people don't experience this. All agree that it is achieved by pushing on when you're tired. Interestingly, one source published in 1907 says that most people do experience it, and a recent one says that people used to get it more often decades ago.

I often get this 'second wind' at international rugby matches. It usually at about 10h30pm after about 9 or 10 pints and some food. Second wind kicks in just after I feel like I'm fading, then it's on to the vodkas !!

Blitzkrieger

Maybe it's just that most people don't push themselves that far anymore? These days everybody has a 'work out' and hardly anyone goes past the hour mark. I remember when I was a kid playing soccer I'd feel knackered after about 45 mins, but when I kept playing I'd get a second wind and we'd often play for four or five hours.

cregser

I know the feeling. I used to do long distance swimming. I'd be in a 1,500m race and after about 500m you'd be dreading the next 1,000. But after about 800m you just get into a rythym and feel really comfortable.

I've noticed the same playing football. Even when I'm not fit, I can get a 'second wind' that last ages. It can be deceptive as built up lactic acid punishes your mucsels the next morning!