short chain fatty acids

Question 1

SCFA

Answer 1

from dietary fibre
are fermented bu gut microbiota to SCFA
include acetic acid, propionic acid, butyric acid
have potential to improve exercise performance and recovery
health benefits- glucose control, anti inflammatory effects with increased SCFA availability

Question 2

SCFA in gut

Answer 2

~100ml/kg- split in 60:20:20 of Ac:Pr:Bu
~70% of colonocyte energy demands
systematic - acetate= 70umol/L
propionate=5umol/L
butyrate=4umol/L
SCFA receptors - GPR41, GPR43 + GPR1-09a on liver, skeletal muscle, kidneys, immune cells and lungs

Question 3

SCFA for exercise

Answer 3

fuelling exercise performance- acute
muscular adaptation- chronic
inflammation and recovery
immune health

Question 4

fuelling exercise performance

Answer 4

SCFA can be oxidised in the TCA cycle
acetate- 10ATP/mol= 73kcal/mol
propionate- 18ATP= 131kcal
butyrate- 27ATP= 197.1kcal
~5-10% of daily energy demands met by SCFA oxidation

Question 5

study- oxidation

Answer 5

SCFA increase whole body energy expenditure and lipid oxidation at rest
specifically propionate

ingestion of acetate increased plasma FFA, increased fat and decreased CHO oxidation during submax exercise, acetate oxidsed during exercise

acetate infusion increased pre exercise muscle acetyl carnitine and acetyl coA content
however has no effext on activating oxidative phosphorylation in he early stages of exercise due to lack of PDH activity

Question 6

muscular adaptation

Answer 6

gut microbiome changes (specifically increased SCFA production) may be a mechanism contributing to exercise improvement at altitude
acetate and butyrate supplementation with training led to increase running time to exhaustion in mice

increased mitochondrial number (increased oxidative capacity) and function suggested as key mechanism for improvement
acetatic acid supplementation led to increased oxidative capacity in mice + increasrd type 1 muscle fibr
decreased muscle damage at the end of exercise

Question 7

inflammation and recovery

Answer 7

exercise induced muscle damage is a common occurence for all athltes
primary damage- consequence of mechanical work performed
secondary damage- associated with inflammatory response
inflammation is a sophisticated and necessary process for positive adaptation
however, prolonged inflammatory response can be detrimental to future training and esponse

Question 8

studies inflammation

Answer 8

supplementation of SCFA showed decreased muscle damage at end of exercise

Question 9

inflammation primary phase

Answer 9

how inflammation occurs after exercise

post exercise Ck and myoglobin stimulated pro inflammatory cytokine release, pro inflammatory cytokines stimulate initial immune response, SCFAs via GPR43 activation- can induce neutrophil recruitment

neutrophils release ROS to carry out their function, too much ROS can damage healthy tissues, some ROS types are more destructuve than others, butyrate has been shown to reduce the production of MPO (Myeloperoxidase- catalyses formation of ROS) in a human ulcerative colitis model
MPO is released by neutrophils but over production can lead to tissue damage

Question 10

inflammation transition phase

Answer 10

need to shut down the pro inflammatory process
SCFA, prebiotics and synbiotics decrease the pro inflammatory biomarkers (CRP, IL-1B, IL-6, IL8 + TNF-a)
all of these biomarkers have been reported as elevated post exercise

Question 11

inflammation secondary phase

Answer 11

need to initiate the anti inflammatory and regenrative process, IL-10 stimulated macrophage phenotypic change promoting muscle growth and regeneration, IL-10 release increased with butyrate treatment in vitro

Question 12

inflammatory summary

Answer 12

SCFAs can affect function of immune cells eg neutrophil ROS prod
SCFA have been associated with anti inflammatory effects- in vitro, animal studies + diseased human populations
current evidence for reducing of EIMD (doms) are theoretical

Question 13

immune health + performamce

Answer 13

illness or injury resulting in missed training significantly lowers chances of success of elite athletes
in 6 months prior to an event, <2 injuries and completing >80% of training increased chances of achieving golas at the event
to maximise likelihood of success in elite athletes, equal attention should be paid to injiry and illness prevention
athletes in intenstive training blocks, sleep deprivation, lower energy intake may be more suscesptible to infection

Question 14

SCFA and immune health

Answer 14

SCFA can have protective effect from UTRIs, reduced tissue damage and increased patrolling monocyte count

butyrate can reduce symptoms of GI tract conditions from travelling