Low Fat High Carb Diet For Athletes Flashcards
Training and periodization for athletes
Systematic approach to achieving improvements in physiological function via the integration and periodization of a series of workouts
Nutrition periodization
- how?
Strategic combined use of exercise training and nutrition, or nutrition only, with the overall aim to obtain adaptation that support exercise performance
- achieve improvements in metabolic efficiency and metabolic flexibility (transporters, enzymes, fatigue resistance, energy stores) - less oxygen to perform well
Carbohydrates is a
- primary fuel for
- ATP production?
- primary substrate for
- aerobic oxidation of it requires
Key substance for performance - limited supply in the body
For CNS
Less oxygen demand
High intensity exercise (>30s and up to 4 hours)
Pyruvate dehydrogenase
Why is carbohydrate easier to use?
We dont have to add as much oxygen
Daily requirements of carbohydrates -2
Levels provide sufficient carb for muscles and CNS needs - should go up according to the intensity level
Light - 3-5g/kg
Mod - 5-7 g/kg
Endurance - 6-10g/kg
Extreme - 8-12g/kg
Low availability desired at times of specific training stim and adaptive response (train low)
Carb requirement during event - 3
Endurance and ultra endurance targets
Bars, gels, beverages, etc
Shorter duration - carb mouth wash may enhance performance by activating reward centres in the brain
Multiple transportable carbs for events longer than 2.5 hours
30-60 and up to 80g/h
What kind of carbs should you consume
A mix
Theory of metabolic effects with low glycogen training
Train with low glycogen stores in order to increase ability to oxidize fat and spare glycogen
Acute metabolic effects of low glycogen training
Upregulation of AMP activated protein kinase (AMPK)(fuel gauge of the cell), GLUT4 (takes in sugar), Hexokinase, Pyruvate dehydrogenase
Why has training low received so much attention
Generally shown beneficial effects in term of signaling and transcription, but to date, few studies showed any effects of performance
Adaptations that are initiated by exercise can be amplified or dampened by
Nutrition
How to improve longer term training adaptations?
Careful planning and integration of nutrition and training
Nutrition should be periodized and adapted to?
Support changing individual goals, training levels, and requirements throughout a season and/or training cycle
Training low
Training with low carb availability - low muscle or liver glycogen, low carb intake during or after exercise, or combination
Rationale for training low found in links of studies
Observed links between carb availability (muscle) and gene expressions - training adaptations were believed to be the results of accumulated small changes in protein synthesis that result in an altered phenotype and improved performance
Rise in AMP activated protein kinase -2
Metabolic change that occur as a result of muscle contraction - important factors in regulating gene transcription. Single bout of endurance exercise will increase AMPK and transcription and/or messenger RNA content for various metabolic and stress-related genes
4 ways to train low
Twice a day Fasted Low exogenous carb availability Low carb availability during recovery Sleep low Low carb high fat ketogenic diets
Training twice a day
Limited or no carb intake between two sessions, first will lower muslce glycogen so second is performed in low glycogen state - may increase expression of relevant genes
Training fast
After overnight fast, muslce glycogen may be normal or even high but liver glycogen is low
Training with low exogenous carb availability
No or very little carb is ingested during prolong exercise, may exaggerate stress response
Low carb availability during recovery training
No, or very little carb ingested post exercise, may prolong stress response
Sleep low
Train late in the dat, go to bed with carb intake resisted for an extended period of time, may last for a while, muslce and= liver glycogen will be low for several hours during sleep
Low carb high fat training
Long term carb stores
Link between muslce glycogen and AMPK
Lower muscle glycogen = greater AMPK Expression
Other signaling molecules with AMPK
P38 mitogen activated protein kinase and expression of PGC 1 alpha
What did training twice a day produce?
Marked improvements in markers of oxidative capacity and citrate synthase
Most common way to train low
Training in an overnight fasted state - more effective to increase muscle oxidative capacity, observed that intramuscular fat utilization was increase with blood glucose levels
Glucose ingestion and AMPK
Attenuate the rise of - long term suppression - reduce increase in CS activity - reduce glycogen accumulation
2 neg effects of training adaptations with low exogenous carb availability
Fatigue
Reduced exercise capacity
High fat diet - 2
Increase fat oxidation - maybe by increasing enzyme activities related to fat and decrease metabolism of carbs.
Compromised pyruvate dehydrogenase activity
Ketogenic diet
No study shows performance benefits of ketogenic diet - no data on ketogenic diets in athletes
Carbs in the first hours after exercise?
Restricted as it is linked to enhanced expression of peroxisome prliferator -activated receptor gamma coactivator 1 and an improved metabolic adaptation to exercise
Sleep low training
Small but significant effect on performance - increased after.3 weeks in sleep low.
GI tract and training - 2
Critical role in delivering carbs and fluids during prolong exercise and can therefore be a major determinant of performance
Incidence of GI problems is high in endurance events - GI function not always optimal in those conditions
High carb diet in GI
Increase number of sodium glucose co transporter in intestines as well as the activity of the transporters - greater carb absorption and oxidation during exercise
Adaptations to a ketogenic diet increases?
Whole body fat oxidation during exercise - reduced economy
LCHF diet in contrast to diets with chronic/periodised high carb availability
Impairs performance
High CHO availability
Beneficial for competition sessions and specific training sessions where high intensity exercise and performance outcomes are required, but unnecessary when sustained intense exercise is less important
Training low is supposed to - 2
Promote greater cellular adaptation to training and enhance performance to a greater magnitude
Or maximize fat as a substrate for exercise with a LCHF diet
Key argument in favour of LCHF
Even the leanest athlete has an abundance of endogenous lipid stores compared to their limited carb reserve - diets high in fat upregulates the release, transport, uptake and utilization of fat in the muslce even in endurance athletes where this would have happened already.
Guidelines for LCHF diet
<20g/day CHO and high fat (80%) of energy, protein 15-20%- ketogenic
15-20% CHO and 60-65 fat - restricted CHO
2 purposes of ketogenic diet
Increase utilization of fat as muscle fuel
Expose body to high levels of circulating ketones
Study that looked at LCHF diets had 3 groups
High CHO 8.6g/kg
Periodized CHO 8.3g/kg
Low CHO high fat less than 50g/day
pre and post test block activities
2 training camps, 21 race walkers - 8 did it twice
29 data sets
graded economy and vo2peak
10k race walk
25l standardised long walk with economy and substrate at 1, 13, 25 km
pre and post block pre race meals?
self selected CHO rich
HCHO and PCHO was the same post race, LCHF was a self selected LCHF
How does Periodized CHO availability work?
same overall macro compostition but spread differently between and within days according to fuel needs of training and integration of some traing sessions with high CHO availability - high muscle glycogen, CHO feeding during session and others with low CHO availability (low pre exercise glycogen, overnight fasted or delayed post-session refueling)
how did they motivate people to do better in the study?
prize money was given to place getters and highest percenrage of their 20 km personal best when two races were combined
result of LCHF diet in O2 cost
increase in post treatment values for absolute and relative O2 cost of exercise/min compared to HCHO while it remained constant in PCHO and HCHO - reduced economy
RER values and LCHF
reduction in post treatment trial while it remained constant in the other groups
substrate utilization and LCHF
large reduction in CHO oxidation rates and increase in rates of fat oxidation
fat oxidation and LCHF
time line of adaptation and who does it work for?
peak can exceed 1.9g/min and this adaptation happened in 3 weeks with high fat pre and during exercise
well trained athletes
mechanisms for the down regulation of CHO metabolism - 3
reduced availability of CHO substrates, reduction in glycogenolysis during exercise and reduction in the active form of pyruvate dehydrogenase at rest and during exercise of moderate and supra maximal exercise
CHO vs fat in ATP production
greater ATP/unit of oxygen consumption despite the greater ATP production of per unit of substrate from fat
endurance and ultra endurance events
multi stage road cycling, triathlons, and marathons - sub maximal exercise intensities but critical parts of the race are often conducted at higher or near maximal pace and requires high exercise economy.
effect of low carb diet on gut absorption of CHo
likely to be reduced, same way that an increased intake can improve the capacity for muscle use (exogenuse CHO sources concumed during the exercise
chronic metabolic effects with low glycogen training 1-3
increased activation of AMPK, p38 MAPK, and PGC 1alpha which
- increases citrate synthase (in the kreb cycle) and cytochrome oxidase activity (mitochondrial biogenesis) (rate limiting factor or ETC
- increased fat oxidation
- decreased pyruvate dehydrogenase
low glycogen will increase your fat oxidation but what else needs to happen?
reduced intensity
Sleep low and periodized low carb training - 2
beneficial ergonomic effects
running time decreased and improvement on few other tests
metabolic characteristics of keto adapted ultra endurance runners
compared to highly trained ultra endurance athletes consuming HC diet, long term keto - high rates of fat oxidation where muscle glycogen utilization and repletion patterns during and after a 3 hour run are similar
1983 LCHF DIET
pro fat as it didnt impair performance
ketogenic and glycogen store in muslces
same
10k race times results
HCHO and PCHO both improved race times but performance did not change with LCHF diet
conclusion of walking economy test
adaptations to chronic LCHF impairs performance in endurance athletes
train chronically low, compete high?
tolerability of the gut
the day of - wont be able to do high power outputs because you cant use carbs well (decreased activity of PD) - depletion of performance
Kenyan endurance runners diet prior to competition
67.3%, 9.8g/kg =552g CHO/day
Kenyan distance runners diet
76.5%, 10.4g/kg = 607g CHO/day
ultramarathoner who won the sydney melbourne race (960km) in 5d, 5h, 7 min - race nutrition
95.6%, 10,540kcals/day, 96g CHO/hr
multiple transportable carbs - 2
glucose and galactose go through SGLT into blood stream - diff transporters your body needs to adapt and have enough channels to get the sugars into the blood
carbs are important fuel source for?
muscle and the brain during exercise
periodized low carb training may have
performance benefits
clear performance benefits associated with LCHF diets?
no
