Lecture 7: Non-nutritive Supplements Flashcards
How does the US army get caffeine and why?
Gum, since caffeine is best absorbed via the mouth
Which groups should limit their caffeine intake?
- Children (
Paradox of caffeine & coffee
Although caffeine decreases insulin sensitivity, long-term coffee drinking decreases risk of T2DM. This is because there are many other compounds in coffee; complex food interactions.
Mechanisms: how caffeine increase sport performance
1) Increase fat metabolism (carnitine) to spare glycogen (this glycogen can be used for sprint at the end)
2) Directly affect skeletal muscle – increase excitation-contraction
3) CNS effect; makes you feel good
Caffeine increases ENDURANCE performance by…
3% (on average)
Another study found ~14% (not likely)
Supplementation protocols for caffeine
- ~6 mL/kg 1 h before exercise (300-500 mg)
- New evidence shows less is also effective
- Doesn’t matter how or when it’s taken, many times have shown to be effective
Individual differences in response to caffeine is likely due to…
genetics
Detrimental effects of coffee (perhaps)?
Health
- CVD
- Certain cancers
Dose of caffeine per day (for no health consequences)
Long-term effects of drinking coffee (good for health)
Decreased risk of liver cancer & T2DM
Caffeine increases STRENGTH performance by…
~ 4%
Supplementation aim
Develop a personalized protocol that is effective for them using the least possible dose
Buffers work to prevent…
Acidosis & alkalosis
What do buffers do?
Inhibit negative consequences of lactic acid formation
How is lactic acid formed? What happens after it’s formed?
Pyruvate + NADH -> Lactic acid + NAD+
Lactic acid -> lactate + H+
Is lactic acid bad?
No, the H+ from breakdown is bad. The lactate is not.
Why is acid bad for exercise?
1) Inhibits actin-myosin crossbridge formation
2) Inhibits various enzymes
3) Feels uncomfortable, burns
Factors affecting lactic acid formation
1) Anaerobic respiration
2) More reliance on glycolysis (untrained person)
3) More use of type 2 fibres (fast-twitch)
4) Clearance of lactate from blood
(efficiency of oxygen use, how circulation distributes oxygen)
Two buffer systems we studied
1) Sodium bicarb (oldest)
2) Beta-alanine
Where does bicarb naturally exist?
extracellular space
How does bicarb works as a buffer?
- increase pH extracellularly
- increase buffering capacity
define: buffering capacity
the body’s ability to handle increasing acidic load
When is bicarb most effective?
- sports lasing 1-7 min (best evidence)
- sprinting to finish after 30-60 min effort (maybe)
- intermittent-type sports (maybe)
AIS: class for bicarb
class A
Negative effects of bicarb
GI distress
Dose for bicarb
0.3 g/kg taken 2-2.5 h before start of exercise. GI distress may decrease if taken with a meal.
Where does B-alaine work?
intracellular
Carnosine =
L-histidine + B-alanine
protein found inside muscle cells (natural buffer)
Why don’t we take carnosine? Why take B-alanine instead?
Body can’t absorb carnosine. Since B-alanine is the rate-limiting precursor, supplementing with B-alanine will increase carnosine levels.
Supplementation of B-alanine / guidelines / how to take it
Need loading phase followed by maintenance phase:
- 4 - 6.4 g/day increases carnosine by 60% after 4 weeks (take for at least 4 weeks)
- 80% increase after 10 weeks
- Divide dose over 0.8 - 1 g servings
- Lower doses over longer time have also been effective
Which sports is most beneficial if taking B-alanine?
high intensity anaerobic exercise
AIS classification of B-alanine
Class A (used to be class B)
How does B-alanine make one feel?
Paresthesia: tingly, i-feel-ready feeling
Negative effects of B-alanine
Not many studies have been conducted
- Does not always work for everyone
- No side effects discovered as of yet
Once B-alanine is “loaded”, how long does buffering capacity last?
6 - 15 weeks (so make sure you take it in advance of most intensive training period)
What’s special about beetroot juice?
nitric oxide (NO)
What is NO?
physiological signalling molecule
Functions of NO
- vasodilation*
- angiogenesis (blood vessel formation)
- regulation of blood pressure
- mitochondrial respiration
- mitochondrial biogenesis
- glucose uptake
Synthesis of NO in humans
L-arginine + O2 (in the presence of synthases) -> NO
Reduction of nitrate (NO3-) and nitrite (NO2-). These can come from diet!
Study outcome: effect of dietary nitrate on oxygen cost during exercise (also, what type of nitrate source was used?)
Took supplemental form of NO3-
- 82% increase in plasma nitrite concentration
- Reduction of BP
- **Need less oxygen to do sub-maximal exercise (changed VO2Max)!!!
What control was used for beetroot juice? What’s a better control?
blackcurrant cordial ;
nitrate-free beetroot juice
Supplement for nitrate?
beetroot juice
Why is beetroot juice > beets?
- more convenient
- nitrate content changes depending on how you cook it
- need to eat A LOT to get desirable dose
How to supplement with nitrate?
- 5-9 mmol of nitrate/day for 1-15 days improves physiological response to exercise
- also 2-3 h before exercise
Duration of benefit after taking beetroot juice?
5-30 min of continuous max effort exercise
