altitude nutrition Flashcards
what is energy availablity
Remaining energy after exercise used for other body functions
what happens if there is low energy availbility (sex hormones)
suppression in reproductive sex hormones: Oestrogen/Testosterone
Low energy availability can suppress reproductive hormones like oestrogen and testosterone, which affect haematological adaptations. This suppression due to low energy can lead to inhibited haematological responses to altitude.
Needed for haematological (HBmass) adaptations.
Oestrogen inhibits iron absorption
how does low energy avalbility increase risk of immune function?
A low energy availability also increases the risk of illness due to immunosuppression. If an athlete falls ill over the time of a altitude camp, this has a negative effect on adaptations in Hbmass.
why is iron important for altitude trainers
Previous studies have shown that if an athlete arrives at an altitude camp in an iron deficient state and does not supplement with iron throughout the camp does not increase Hbmass.
dosage of iron for altitude training
Optimal iron dosage lies between 100 and 200 mg of iron per day, with 200 mg maintaining ferritin levels whilst improving Hbmass
how is iron absorption controlled
Iron absorption is controlled by the hormone hepcidin and the concentration of this hormone in the blood follows a circadian rhythm
timing of iron intake important for altitude training
the lower hepcidin, the better the iron absorption, so iron supplementation will be most beneficial in the morning and less beneficial in the afternoon or in th time after exercise
consume 100-200 mg iron in a single dose in
the morning, ideally co-ingested with vitamin C, which promotes iron absorption.
evidance why weight loss occur when altitude rises
in the meta-analysis by Dunnwald et al. (2019):
It was discovered that at extreme altitudes, individuals can lose up to 5 kg of body weight, with a significant portion coming from fat-free mass.
The extent of weight loss depends on various factors, including duration of exposure to altitude and genetic predisposition.
Highlanders, such as Sherpas or Tibetans, maintain body mass throughout their lives at high altitudes.
Conversely, lowlanders, like the average European, are less adapted to high altitudes and experience more pronounced changes.
what are the causes of weight loss
At high altitudes, reduced energy intake can be attributed to decreased appetite, regulated by hormones like leptin from adipose tissue. Leptin levels increase at high altitudes, resulting in reduced hunger.
This is particularly evident in individuals experiencing appetite loss at 4450m altitude, who exhibit higher leptin levels compared to those who don’t, even surpassing their own levels at sea level. Furthermore, longer exposure to altitude leads to even higher leptin levels, intensifying appetite suppression and consequent reduction in energy intake.
nutrtional startergies to combat weight loss (monitor energy intake)
Energy intake should be closely monitored during the expedition to get estimates.
Nutritional strategies to combat weight loss (Foods should be energy dense)
To increase energy intake, but not affecting appetite, foods should be energy dense. This can involve snacks with high carbohydrate and fat contents.
Nutritional strategies to combat weight loss (Protein intake has to be considered)
Protein increases satiety and therefore potentially compromises energy intake
Alternative is to use BCAA or leucine-enriched products..
To boost muscle protein synthesis, it might seem logical to eat more protein. But whole proteins can make you feel full, reducing how much you eat. Instead, you could try other nutrients like branched-chain amino acids, especially leucine, to still help your muscles without filling you up too much.
why should you consider iron supplements
Expeditions can also have a haematological effect (reductions in haematocrit or haemoglobin) that could negatively affect performance. Therefore, consider the intake of iron supplements.
evidance of why to consider muscle protien synthesis
STUDY Holm et al 2010
Holm et al. found evidence suggesting an increase in muscle protein synthesis (MPS) at altitude. They measured MPS at baseline, then after participants spent 7-9 days acclimatizing to high altitude.
Despite this increase, it appears contradictory to previous explanations. However, Holm et al. also observed an increase in whole-body protein turnover at altitude, suggesting increased protein breakdown, possibly resulting in a negative protein balance over time.
Additionally, participants maintained their diet from sea level, avoiding an energy deficit, which differs from conditions during an Everest expedition..
why is iron effective - study
(GOUSE ET AL 2015)- separated them into whether they were iron deficient before the start or had normal levels before the training cam…
Found :If you are iron deficient before the start of altitude camp( not eating enough iron or even supplementing iron throughout the altitude camp) – there is no benefit on the changes in haemoglobin mass, so you wont be getting those adaptations that you are trying to achieve at the camp
He then looked at the group who was iron deficient tat the start , but then received supplements throughout the altitude training camp…
Found: athletes where able to increase their haemoglobin mass
He had a control group who had people who had normal iron concentrations before the start of the altitude camp and supplemented with iron throughout
Found: saw good haemoglobin mass adaptations
Suggest that iron status In an athlete is very important to attain those beneficial adaptations
