Hydration and nutrition for exercise
- Eating carbohydrate before exercise will suppress fat burning and encourage the burning of the recently consumed carbohydrate.
- Some carbohydrate needs available to the body to enable it to burn fat.
- See the following link for an article that considers exercise and the role of carbohydrate with regards exercise performance, exercise recovery and exercise and weight loss:
- Eating carbohydrate before and during exercise can improve exercise performance.
- Intentionally building up carbohydrate in the body before exercise is called "Carbohydrate Loading".
- The order of nutritional needs during exercise is for the provision of fluid, carbohydrate, and sodium.
- Fluid replacement during exercise should match sweat loss much as is practically possible.
- For a video about sweat and sweating (which displays some preserved human body parts) see the following link:
- Separate and additive performance benefits can be gained from consuming fluid and carbohydrate during exercise.
- Exercise performance is improved with the ingestion of between 30g to 60g of carbohydrate per hour, for events greater than an hour and up to 90g per hour for events greater than 2.5 hours.
- Sodium lost through sweat during exercise should be replaced by consuming fluid with sodium in it during exercise and consuming sodium after exercise which is perhaps easiest done by well salting post exercise food.
- For long continuous reasonably high intensity exercise sessions (burning in the range of about 1,500 to 2,000 Kcals) the human body does not have enough readily convertible fuel stores to continue to provide enough glucose to fuel it and therefore carbohydrate refuelling (or reducing intensity) is required to avoid "hitting the wall". Hitting the wall is caused by glycogen depletion (glucose is stored in the body as glycogen. Glycogen is mainly stored in the liver and muscles. About 100g of glycogen is stored in the cytoplasm of liver cells and used mainly to maintain blood glucose levels and about 400g is stored in the cytoplasm of muscle cells and provides a rapidly available energy source to power them).
- For an article that discusses whether to eat before, after and before and after exercise see the following link:
- For good articles about exercise hydration and nutrition needs see the following links:
- https://theconversation.com/health-check-whats-the-deal-with-electrolytes-31729
- https://www.precisionhydration.com/blogs/hydration_advice/how-does-precision-hydration-fit-in-with-your-nutrition-plan?_pos=2&_sid=b0cadf456&_ss=r
- For an article that discusses how to train to adapt to exercising in a hot environment see the following link:
- For an article about exercise fuelling for a long exercise session (in this case a marathon run) see the following link:
- For an overview video about exercise fuelling for a long exercise session (in this case a long bike ride) see the following link:
- For some research about the comparison of different exercise energy fuel types see the following link:
- For a good article about exercise energy products compared to real food see the following link:
- Sugar:
- For a video about sugar and sugar and exercise (which displays preserved human body parts) see the following link:
- For an article about different sugar types for exercise energy see the following link:
- For an article that explains the differences between different types of sugars see the following link:
- For an article that clarifies the many different names given to sugars see the following link:
- For some concise information about the different types of sugars in fruits and some other foods see the following link:
- For a video about the nutritional value of different sugars see the following link:
- See the link that follows for a detailed position statement from some key North American institutions about nutrition and athletic performance:
Some key (and good to know) high level human food energy science
- The energy sources the human body uses in the fed state, if available, are as follows (the Kcal values given take into account standard adjustments for incomplete digestion and absorption by the body to provide the metaboliseable energy value for the food type. Adding food items to a meal which are high in fiber can reduce these values):
- Fat = 9 Kcal / gram.
- 2.25 times the energy of carbohydrate but the body takes longer to make the energy available from fat and so as exercise intensity increases the proportion of fat to carbohydrate burnt decreases. The fats are in the form of free fatty acids (FFAs) and muscle triglyceride.
- 2 - 3 % of the total calories are lost when processed by the body to store for energy use as stored fat.
- The bodies stored fat provides a large energy store.
- Alcohol (Ethanol), a hydrocarbon = 7 Kcal / gram.
- Cannot be stored by the human body and seen by the body as a toxin so alcohol is metabolised as fast as the body is able to manage with this occurring at a standard linear rate. As a consequence other energy sources are down regulated to accommodate this and their metabolism is inhibited leading to fat storage / conversion to fat and then storage when the body is in positive energy (calorie) balance. Alcohol has no nutritional value and only up to about 10% is excreted.
- For more key information about alcohol see the section in the Weight tab and for detailed information about alcohol metabolism see the following link:
- Carbohydrate = 4 Kcal / gram.
- Carbohydrates are converted to glucose (if not already glucose) and glucose is then utilised from the blood and from glycogen stored in muscles and the liver (which delivers glucose to the blood) to produce energy. About 100g of glycogen is stored by the liver. About 300g of glycogen is stored in the muscles in sedentary individuals and up to about 500g in exercise trained individuals.
- 5 - 6 % of the total carbohydrate calories are lost when processed by the body to store for energy use as Glycogen and about 23% when converted to fat as the energy store although this doesn't normally occur for significant amounts.
- The body can only store a limited amount of carbohydrate as carbohydrate (around 1,500 to 2,000 Kcals).
- For a great article and a video (which shows preserved human body parts) about sugars see the following links:
- For more information about sugar see the Hydration and nutrition for exercise section above.
- Dietary fibers are complex carbohydrates.
- Soluble fibers = 2 Kcal / gram.
- Insoluble fibers = 0 Kcal / gram.
- For an article about dietary fibers see the following link:
- Protein = 4 Kcal / gram.
- 20 - 30 % of the total calories are lost when processed by the body and stored for energy use. Although protein in not normally used as a significant energy source.
- The ratio of food energy sources used by the human body to create energy depends upon; the time of the day, activity/exercise intensity level and duration, training status, sex, genetics and the food derived energy sources available to it (recent as well as ongoing). However the body processes food energy sources with the following general priorities; alcohol if present, then as much carbohydrate as available (driven by the more immediate needs for energy), followed by fat and then protein. The body can processes energy sources concurrently so long as body state allows it and the energy source is available.
- For the source of the above diagram and further information see the "Bioenergetic" section in the following link:
- For an explanation of the above diagram see the following:
- The diagram shows the relative energy potential from each of the bodies energy systems looked at from the perspective of going from rest to a maximum sustainable exercise workload (from 0 to about 6 or 7mins). The energy systems exist within cells that make up the human body via the process of cellular respiration which generates heat and ATP. ATP is the primary source of energy utilised by the human body and humans utilise and then recycle about their own bodyweight in ATP everyday.
- Immediate anaerobic (Nonoxidative) - Very rapid but only available for very short high energy use bursts
- 0 to 30 secs
- Uses ATP already available in the body
- 0 to 10 secs ~ 100% of total
- 10 secs to 20 secs ~ 50% of total
- > 30 secs ~ 0 % of total
- ~ 3mins of total rest to fully replenish
- Anaerobic (Nonoxidative) - Rapid but only available for short high energy use bursts
- 30 secs to 80 secs
- Anaerobic glycolysis; generates ATP and pyruvate from glucose and then produces lactic acid (lactate) from the pyruvate as oxygen is not able to be utilised quickly enough. Lactate generates more ATP following the further production of pyruvate from further anaerobic glycolysis.
- 20 secs ~50% total
- 30 secs to 80 secs ~ 100% total
- 120 secs ~ 50% total
- 300 secs ~ 25% total
- 1hr to remove all lactate but most removed after 10mins at an increasing rate below the exercisers lactate threshold.
- Excess lactate reduces exercise rate and acts as a rate limiting control on the body.
- Aerobic (Oxidative) - Sustainable for long periods at high energy use rates
- Aerobic 1 to 3 mins to peak production
- Aerobic glycolysis; pyruvate from glucose glycolysis to generate ATP via the aerobic Krebs cycle (aka tricarboxylic acid cycle or citric acid cycle) and then the bulk of ATP (~90% of total ATP that can be generated from glucose) via the aerobic Electron Transfer Chain both which occur within the mitochondria within cells. This takes place until no further stored glucose is available which occurs after about 1,500 to 2,000 Kcal of glucose derived energy expenditure has taken place if no refuelling that can create glucose occurs. Rehydration is also required.
- 60 secs ~ 75% total
- Aerobic (Oxidative) 6 to 7 mins - Sustainable for long periods at lower energy use rates
- Aerobic lipolysis; ATP generated from lipids (fats) via the Krebs cycle can contribute energy so long as exercise intensity allows it with a low contribution if the exercise intensity is too high. The proportion of aerobic lipolysis (fat burning) to aerobic glycolysis (carbohydrate/glucose burning) is determined by various factors e.g. fitness but it is primarily determined by exercise intensity.
- The Respiratory Exchange Ratio can indirectly measure the proportions of fat to carbohydrate/glucose burned via the ratio of CO2 and O2 in the inhaled air compared to the ratio in the exercisers exhaled air.
- For a video that discusses bioenergetics from an exercise training perspective see the following link:
within glycogen (stored in muscles and the liver), 3 ATPs are yielded from glycolysis.
- Schematic overview of glycolysis and mitochondrial respiration. Source:
- For a video about mitochondria see the following link:
- Overview of relevant nutrients in bioenergetic mitochondrial processes. Several nutrients are involved in the formation of acetyl CoA, which is essential in energy production as it is the starting point of the TCA cycle. Thiamine (vitamin B1) is essential for the conversion of pyruvate to acetyl-coA. Furthermore, high levels of zinc were found to inhibit the glycolysis and TCA cycle. Carnitine is essential in βeta-oxidation of free fatty acids. In addition to the formation of acetyl CoA, several nutrients have an direct effect on the TCA cycle. Pantothenic acid (vitamin B5) is the precursor of CoA. Vitamin B 12 is an essential cofactor in the formation of succinyl-CoA, an important metabolite of the TCA cycle. Besides, several nutrients influences the activity of the electron transport chain. Niacin (vitamin B3) is the precursor of NAD+, which has a crucial role in the formation of NADH, which on turn plays a crucial role in the electron transport chain. Complex I and IV activity is decreased during critical illness, but several nutrients positively affect complex I and IV performance. Complex I and IV may be stimulated by selenium, caffeine and melatonin. Complex I and II are also stimulated by CoQ10. Taurine depletion is associated with impaired activity of complexes I and III. Whether the effect of vitamin E on the complexes I and IV is stimulating or inhibiting has not yet been revealed. Nitrate probably inhibits complex IV activity. Riboflavin (vitamin B2) is an important building block for complexes I and II and involved in fatty acid oxidation in the TCA cycle. α-KGDH: alpha-ketoglutarate dehydrogenase; ATP: adenosine triphosphate; CoA: coenzyme A; CO2: carbon dioxide; CoQ: coenzyme Q; NAD(H): Nicotinamide adenine dinucleotide (reduced); PDH: pyruvate dehydrogenase; Vit: vitamin. Source:
- For further information about the mitochondrion see the following links:
- For scientific articles about how cells in the human body meet ever changing energy needs see the following links:
- For a video that explains how the body powers itself using a car analogy see the following link:
- https://www.youtube.com/watch?v=8Y_FdjI2v4I
- The video would probably be clearer if it made it explicit that the 3 engine units co-exist (as part of cells) with different energy output capabilities (depending on the cell type / efficiency of the cell) and also that the engines make up the core fabric of the car (cells) and that the different components of the car (made from the core fabric) have different energy producing capabilities (e.g. red blood cells [no mitochrondria], muscles, the liver [multiple mitochrondria per cell], etc), although that may have stretched the analogy a bit too far.
- For a long video that discusses the human bodies use of different fuel sources and the utilisation of protein see the following link:
- For videos that explains how muscles function and how they utilise energy see the following links (preserved human body parts are shown in the video):
- For a video that describes the overall respiration process in humans during exercise see the following link:
- For a video about how muscles in the human body fatigue during a single bout of exercise see the following link:
- For two consecutive videos that explain about different types of muscoskeletal muscle fibre types and how utilise energy differently see the following links:
- For a detailed and comprehensive video that explains the structure and function of human cells see the following link:
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