Human physiology with regards energy consumption
Forum rules
The information / discussion in the Cycling Health Forum is not qualified medical advice. Please consult your doctor.
The information / discussion in the Cycling Health Forum is not qualified medical advice. Please consult your doctor.
-
- Posts: 315
- Joined: Thu Feb 26, 2015 3:33 pm
Human physiology with regards energy consumption
Postby big booty » Thu Dec 10, 2015 2:59 pm
Found a nice article by Romijn et al. (1993) on fat and carbohydrate metabolism and I now have a rudimentary understanding of how various energy sources are utilized at different energy consumption levels. What Im wanting to know more about is how those energy stores get refilled after they have been depleted. For example, if after a long ride you run out of glycogen does the body self replenish the glycogen (from which stock?) or can this only be refilled by eating? Do the intramuscular triglycerides (if depleted) get refilled from adipose triglycerides or once again do you need to eat to refill this stock? And does glycogen storage need to be maxed out before energy is stored as intramuscular and adipose triglycerides? Any and all info gleefully accepted.
-
- Posts: 449
- Joined: Thu Oct 03, 2013 7:59 pm
Re: Human physiology with regards energy consumption
Postby RhapsodyX » Thu Dec 10, 2015 3:43 pm
AFAIK... because I haven't refreshed my memory on this.
The fats/carbs ratio at different outputs is "rule of thumb", the reality is your mitochondria adapt to be carb or fat efficient depending on the predominant fuel source. As for adipose storage... it's an ongoing storage/recovery process with every meal... but different fatty-acid structures are processed differently - so short/medium chain fatty acids are less likely to be stored as adipose tissue than long chain. Hence the interest in coconut oil (<= C12).
Ultimately, everything appears to hinge on insulin. If your insulin levels go up, free-fatty acids in the blood stream are driven to storage rather than consumption which stops them being available as an aerobic fuel source. Also, Insulin response is not the same for all people in response to blood glucose (delayed response, excessive response), so buying a BG meter and starting to map your response to foods is an interesting exercise to start off with. If your blood glucose falls far enough, leptin should increase to release free-fatty acids from adipose tissue, which your liver will then convert into ketones to provide an alternative fuel source - but you also need to be ketone adapted to make use of them. The liver will also convert protein into glucose if your protein intake is above "adequate" levels (see Gluconeogenesis), and blocks ketosis as the same time. And artificial sweeteners appear to be capable of creating an insulin response even in the absence of higher blood glucose.
Read up on "Nutritional ketogenic diet". And the Ketogenic Diet for Epilepsy is a bit over the top - they have admitted that the fluid restriction was probably a mistake.
Have fun researching.
The fats/carbs ratio at different outputs is "rule of thumb", the reality is your mitochondria adapt to be carb or fat efficient depending on the predominant fuel source. As for adipose storage... it's an ongoing storage/recovery process with every meal... but different fatty-acid structures are processed differently - so short/medium chain fatty acids are less likely to be stored as adipose tissue than long chain. Hence the interest in coconut oil (<= C12).
Ultimately, everything appears to hinge on insulin. If your insulin levels go up, free-fatty acids in the blood stream are driven to storage rather than consumption which stops them being available as an aerobic fuel source. Also, Insulin response is not the same for all people in response to blood glucose (delayed response, excessive response), so buying a BG meter and starting to map your response to foods is an interesting exercise to start off with. If your blood glucose falls far enough, leptin should increase to release free-fatty acids from adipose tissue, which your liver will then convert into ketones to provide an alternative fuel source - but you also need to be ketone adapted to make use of them. The liver will also convert protein into glucose if your protein intake is above "adequate" levels (see Gluconeogenesis), and blocks ketosis as the same time. And artificial sweeteners appear to be capable of creating an insulin response even in the absence of higher blood glucose.
Read up on "Nutritional ketogenic diet". And the Ketogenic Diet for Epilepsy is a bit over the top - they have admitted that the fluid restriction was probably a mistake.
Have fun researching.
-
- Posts: 101
- Joined: Sat Jun 15, 2013 8:19 am
Re: Human physiology with regards energy consumption
Postby Constantheadwind » Thu Dec 10, 2015 4:05 pm
Google & wiki is your friend big booty.
Surf furiously!
The diet warring factions will soon chime in, be impartial and open minded.
Surf furiously!
The diet warring factions will soon chime in, be impartial and open minded.
-
- Posts: 572
- Joined: Mon Aug 03, 2015 5:13 pm
Re: Human physiology with regards energy consumption
Postby madmacca » Mon Dec 14, 2015 8:26 pm
What's your objective here? Fat loss, or appropriate fueling for long rides?
-
- Posts: 315
- Joined: Thu Feb 26, 2015 3:33 pm
Re: Human physiology with regards energy consumption
Postby big booty » Mon Dec 14, 2015 9:12 pm
Neither. Ive got a reasonable handle on how the different energy stores are consumed. What I don't have an understanding on is how the energy stores are replenished.madmacca wrote:What's your objective here? Fat loss, or appropriate fueling for long rides?
-
- Posts: 3459
- Joined: Mon Jun 30, 2014 10:23 am
Re: Human physiology with regards energy consumption
Postby CKinnard » Mon Dec 14, 2015 10:13 pm
This is 12 years old now, but is consistent with the current dietary practices of a larger UCI World Tour team.big booty wrote:For example, if after a long ride you run out of glycogen does the body self replenish the glycogen (from which stock?) or can this only be refilled by eating? Do the intramuscular triglycerides (if depleted) get refilled from adipose triglycerides or once again do you need to eat to refill this stock? And does glycogen storage need to be maxed out before energy is stored as intramuscular and adipose triglycerides? Any and all info gleefully accepted.
"Summary
In the process of recovery after exercise, nutrition is a central
consideration for rehydrating and refueling the body. Nutritional
intervention also supports the anabolic events triggered by muscle
contraction and leads to training adaptations.
When recovery time is short between physical challenges, it is even more important to
adopt an adequate nutrient intake proactively and in good time.
Restoration of muscle glycogen is faster when rapidly available
carbohydrates are ingested at a rate of about 1 g·kg body mass–1·h–1
immediately after the end of exercise, preferably as a drink. In
optimal conditions replenishment is achieved within 24 h.
Proteins, when co-ingested with carbohydrates play a subsidiary role
on glycogen resynthesis. On the other hand, ingestion of proteins
in the time frame of exercise is important for rapid tissue repair
and the initiation of muscle building by, in particular, their essen-
tial amino acids. This consideration finds application for muscle
activities involving intermittent resistance work.
The restoration of intramuscular triacylglycerol (mTAG, IMCL) is achieved
within 24 h by the ingestion of about 2 g dietary lipids·kg body
mass–1·day–1.
Extremely high-carbohydrate, glycogen-loading diets consumed for several days after endurance exercise will pre-
vent or inhibit the rapid restoration of IMCL stores. Glycogen
resynthesis proceeds rapidly in the first hours whereas IMCL start
accumulating after a lag time of a few hours. Therefore when
both muscle glycogen and lipid replenishment is required, as is
presumably the case before very prolonged endurance exercise, it
is suggested to initiate recovery with rapidly absorbed carbo-
hydrates followed by addition of lipids in a second phase."
-
- Posts: 449
- Joined: Thu Oct 03, 2013 7:59 pm
Re: Human physiology with regards energy consumption
Postby RhapsodyX » Tue Dec 15, 2015 9:16 am
Thanks for that - that's interesting, and not something you see in any of the sports nutrition books.CKinnard wrote:This is 12 years old now, but is consistent with the current dietary practices of a larger UCI World Tour team. ...
Jump to
- General Australian Cycling Topics
- Info / announcements
- Buying a bike / parts
- General Cycling Discussion
- The Bike Shed
- Cycling Health
- Cycling Safety and Advocacy
- Women's Cycling
- Bike & Gear Reviews
- Cycling Trade
- Stolen Bikes
- Bicycle FAQs
- Serious Biking
- Audax / Randonneuring
- Retro biking
- Commuting
- MTB
- Recumbents
- Fixed Gear/ Single Speed
- Track
- Electric Bicycles
- Cyclocross and Gravel Grinding
- Dragsters / Lowriders / Cruisers
- Children's Bikes
- Cargo Bikes and Utility Cycling
- Road Racing
- Road Biking
- Training
- Time Trial
- Triathlon
- International and National Tours and Events
- Cycle Touring
- Touring Australia
- Touring Overseas
- Touring Bikes and Equipment
- Australia
- Western Australia
- New South Wales
- Queensland
- South Australia
- Victoria
- ACT
- Tasmania
- Northern Territory
- Country & Regional
- The Market Place
- Member to Member Bike and Gear Sales
- Want to Buy, Group Buy, Swap
- My Bikes or Gear Elsewhere
- Cycling Brands
- Cannondale
- Garmin
- Giant
- Shimano
- Trek
Who is online
Users browsing this forum: No registered users
- All times are UTC+11:00
- Top
- Delete cookies
About the Australian Cycling Forums
The Australian Cycling Forums is a welcoming community where you can ask questions and talk about the type of bikes and cycling topics you like.
Bicycles Network Australia
Forum Information
Connect with BNA
Brought to you by Bicycles Network Australia | © 1999 - 2024 | Powered by phpBB ®
This website uses affiliate links to retail platforms including ebay, amazon, proviz and ribble.
This website uses affiliate links to retail platforms including ebay, amazon, proviz and ribble.