Efficiency of the human body

[8Ace]

I spent half an hour on the cross trainer this morning. At the end of it, I felt pretty tired. According to the numbers on the readout, I burned north of 300 calories. Well done me. But I am assuming that this is simply a measure of the energy I was putting into the machine. As nothing is perfectly efficient (I know I'm not, I was sweating like a mofo at the end of it), does anyone know what level of efficiency I was working at. Ie: In putting in 300 cals worth of energty to the Cross trainer, how much did I use myself?

Any ideas? Would be interesting to get a vague clue.

[10 Pence Short]

Was your trainer still cross afterwards, or had she relaxed a bit?

[barney123]

10 Pence Short said:

Was your trainer still cross afterwards, or had she relaxed a bit?

She became a bit dissinterested follwing the above questionning......

[kambites]

According to wikipedia:

The efficiency of human muscle has been measured (in the context of rowing and cycling) at 14% to 27%. The efficiency is defined as the ratio of mechanical work output to the total metabolic cost.[citation needed]

[8Ace]

kambites said:

According to wikipedia:

The efficiency of human muscle has been measured (in the context of rowing and cycling) at 14% to 27%. The efficiency is defined as the ratio of mechanical work output to the total metabolic cost.[citation needed]

Interesting. So even if I'm super efficient (27%), then 300 cals work requires over 1100 calories to produce.

Nice one, I'm off for a Creme egg.

Do the machines measure energy out, or do they adjust for energy in as well?

[Chris71]

kambites said:

According to wikipedia:

The efficiency of human muscle has been measured (in the context of rowing and cycling) at 14% to 27%. The efficiency is defined as the ratio of mechanical work output to the total metabolic cost.[citation needed]

So an IC engine is better?

Government! We need to ban human beings...

[The jiffle king]

8Ace said:

kambites said:

According to wikipedia:

The efficiency of human muscle has been measured (in the context of rowing and cycling) at 14% to 27%. The efficiency is defined as the ratio of mechanical work output to the total metabolic cost.[citation needed]

Interesting. So even if I'm super efficient (27%), then 300 cals work requires over 1100 calories to produce.

Nice one, I'm off for a Creme egg.

Do the machines measure energy out, or do they adjust for energy in as well?

I guess that the machine has already taken this into account. When running, you can look at 100 calories per mile. My guess is that this would take the average person about 30 mins, so 300 calories. X trainer will be different, but you cannot burn 1100 calories in 30 mins

[NoelWatson]

8Ace said:

kambites said:

According to wikipedia:

The efficiency of human muscle has been measured (in the context of rowing and cycling) at 14% to 27%. The efficiency is defined as the ratio of mechanical work output to the total metabolic cost.[citation needed]

Interesting. So even if I'm super efficient (27%), then 300 cals work requires over 1100 calories to produce.

Nice one, I'm off for a Creme egg.

Do the machines measure energy out, or do they adjust for energy in as well?

I believe it is estimating energy expended and not the work actually done.

[dealmaker]

8Ace said:

kambites said:

According to wikipedia:

The efficiency of human muscle has been measured (in the context of rowing and cycling) at 14% to 27%. The efficiency is defined as the ratio of mechanical work output to the total metabolic cost.[citation needed]

Interesting. So even if I'm super efficient (27%), then 300 cals work requires over 1100 calories to produce.

Nice one, I'm off for a Creme egg.

Do the machines measure energy out, or do they adjust for energy in as well?

I think the machines already have the efficiency weighted calculation based on an 85th perecentile "human" (of average gender, weight, height and metabolic rate) programmed in.

So "theroretically" your session "burned" 300 calories - howver I'd be suprised if it was that accurate, and.......you're not going to like this..................but I believe they are woefully optimistic generally as to the amount you have really burned.

So belay that Creme egg order!

[Tuna]

8Ace said:

kambites said:

According to wikipedia:

The efficiency of human muscle has been measured (in the context of rowing and cycling) at 14% to 27%. The efficiency is defined as the ratio of mechanical work output to the total metabolic cost.[citation needed]

Interesting. So even if I'm super efficient (27%), then 300 cals work requires over 1100 calories to produce.

Nice one, I'm off for a Creme egg.

Do the machines measure energy out, or do they adjust for energy in as well?

I'm pretty sure they estimate the amount of energy you have burned, (ie. energy in), not the energy you're putting out.

[eddie1980]

Chris71 said:

kambites said:

According to wikipedia:

The efficiency of human muscle has been measured (in the context of rowing and cycling) at 14% to 27%. The efficiency is defined as the ratio of mechanical work output to the total metabolic cost.[citation needed]

So an IC engine is better?

Government! We need to ban human beings...

Always wondered if cycling everywhere and the carbon costs of the increased food production would be worse then just using a car.

[rhinochopig]

Tuna said:

8Ace said:

kambites said:

According to wikipedia:

The efficiency of human muscle has been measured (in the context of rowing and cycling) at 14% to 27%. The efficiency is defined as the ratio of mechanical work output to the total metabolic cost.[citation needed]

Interesting. So even if I'm super efficient (27%), then 300 cals work requires over 1100 calories to produce.

Nice one, I'm off for a Creme egg.

Do the machines measure energy out, or do they adjust for energy in as well?

I'm pretty sure they estimate the amount of energy you have burned, (ie. energy in), not the energy you're putting out.

I think it depends on the machine - an Ergometer, for example, measures work done.

[NoelWatson]

rhinochopig said:

Tuna said:

8Ace said:

kambites said:

According to wikipedia:

The efficiency of human muscle has been measured (in the context of rowing and cycling) at 14% to 27%. The efficiency is defined as the ratio of mechanical work output to the total metabolic cost.[citation needed]

Interesting. So even if I'm super efficient (27%), then 300 cals work requires over 1100 calories to produce.

Nice one, I'm off for a Creme egg.

Do the machines measure energy out, or do they adjust for energy in as well?

I'm pretty sure they estimate the amount of energy you have burned, (ie. energy in), not the energy you're putting out.

I think it depends on the machine - an Ergometer, for example, measures work done.

For watts, I believe yes, for calories, I think not

http://www.concept2.co.uk/training/bmr.php

[8Ace]

The jiffle king said:

8Ace said:

kambites said:

According to wikipedia:

The efficiency of human muscle has been measured (in the context of rowing and cycling) at 14% to 27%. The efficiency is defined as the ratio of mechanical work output to the total metabolic cost.[citation needed]

Interesting. So even if I'm super efficient (27%), then 300 cals work requires over 1100 calories to produce.

Nice one, I'm off for a Creme egg.

Do the machines measure energy out, or do they adjust for energy in as well?

I guess that the machine has already taken this into account. When running, you can look at 100 calories per mile. My guess is that this would take the average person about 30 mins, so 300 calories. X trainer will be different, but you cannot burn 1100 calories in 30 mins

Bugger. It did sound rather a lot.

• sadly exchanges Creme Egg for sugar-free gum*

[Chairman LMAO]

The machine will factor in energy used in heat production etc...

300kcals reasonable.

[Chris71]

eddie1980 said:

Chris71 said:

kambites said:

According to wikipedia:

The efficiency of human muscle has been measured (in the context of rowing and cycling) at 14% to 27%. The efficiency is defined as the ratio of mechanical work output to the total metabolic cost.[citation needed]

So an IC engine is better?

Government! We need to ban human beings...

Always wondered if cycling everywhere and the carbon costs of the increased food production would be worse then just using a car.

I am told the greener current cars put out less CO2 than joggers...

Never done the sums myself though.

[CC07 PEU]

Wouldn't you know accurately how many calories you burned if you were using a heart rate monitor linked up to the cardiovascular machine?

[fido]

Chris71 said:

kambites said:

According to wikipedia:

The efficiency of human muscle has been measured (in the context of rowing and cycling) at 14% to 27%. The efficiency is defined as the ratio of mechanical work output to the total metabolic cost.[citation needed]

So an IC engine is better?

Government! We need to ban human beings...

Yep, but the IC engine cannot run on cornish pasties, lettuce, and pastries from Tescos .. think i also had a Tracker bar for breakfast. It's still an incredibly efficient multi-purpose machine .. and has featured variable-valve timing (breathing) for a million or so years

Edited by fido on Monday 23 March 16:34

[Jinx]

So all that effort only burned off a pint and a half of Guinness then.....
Hardly seems worth it - time for a

[eddie1980]

Chris71 said:

eddie1980 said:

Chris71 said:

kambites said:

According to wikipedia:

The efficiency of human muscle has been measured (in the context of rowing and cycling) at 14% to 27%. The efficiency is defined as the ratio of mechanical work output to the total metabolic cost.[citation needed]

So an IC engine is better?

Government! We need to ban human beings...

Always wondered if cycling everywhere and the carbon costs of the increased food production would be worse then just using a car.

I am told the greener current cars put out less CO2 than joggers...

Never done the sums myself though.

That would be awsum if true, anyone got the maths on that?!