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2. Ex Phys, Lecture 10 and revision

winniesmith2's version from 2018-05-14 12:48

Section 1

Question Answer
Central fatigue is is related to reduced neural output of central structures (brain)
What is the central governor model (by noakes) …predicts that neural control systems in the brain and spinal cord establish the number of motor units that are activated in the exercising muscles, specifically to ensure that homeostasis is maintained
what is central fatigueAny force decline caused by a reduction in the motoneuron firing frequency. In other words: Reduced excitatory drive from the brain to the motoneuron
What is the role of serotonin 5-HT. Involved in feelings of tiredness and lethargy, mood, sleep, sensory perception, pain, appetite regulation, thermoregulation. Implicated in many psychiatric disorders.
What is the role of dopamineDA. Important in motivation, reward and attention. Also involved in memory, motor control and coordination.
What is the role of noradrenalineNA. Implicated in the regulation of attention, arousal and sleepawake cycles. Learning and memory, anxiety, pain, mood and brain metabolism.
what is the role of adrenalineA. Wide ranging central and peripheral roles; modulates motor behaviour, mood, muscle function, blood flow, thermoregulation etc. Regulates the release of other neurotransmitters such as dopamine and glutamate.
Brain serotonin and central fatiguedo not need to know areas of brain, just need to know it affects all areas.

Section 2

Question Answer
What are the effects of increased brain serotonin during exercise• decreased arousal and motivation • decreased tolerance to pain/discomfort • increased lethargy & tiredness
Drug induced performance gains- innfluencing serotonin pathways. Rates running at 20m/min (to exhaustion) 5% grade, before exercise injected with either: Saline (control), 5-HT agonist (chemical that binds to receptor, trigers response) and 5-HT antagonist. Antagonist had highest endurance time.
BCAA and Trp share whattransporters over blood brain barrier.
Trp is an essential amino acid for whatto build serotonin.
What happens due to increased free fatty acids in exercisemore in circulation. These bind to albumin to release trp. Therefore more free trp in blood stream (ratio of trp to bcaa is higher). Our BCAA decrease as muscle may use them for energy. Due to high trp ratio, more trp transported to brain side, which is used to produce more serotonin.
What happens if you add BCAAmore BCCA in circulation, decreasing the ratio of BCAA and trp's. therefore less trp transported across barrier to brain and less serotonin produced.
Does BCAA supplementation seem to workno, nice theory but in practice doesn't seem to work.
What do amphetamines do increase brain dopamine activity. Optimal does of 2.5 to increased running endurance in rats.

Section 3

Question Answer
Brain dopamine and central fatigue plays important role in • Motivation & reward • Pleasure • Motor control & coordination
What happens to dopamine synthesis & metabolism during exerciseincreases. But fatigue coincides with ↓ synthesis & metabolism • Maintaining brain dopamine synthesis & metabolism delays fatigue
What is the use of TYRsynthesis of dopamine. used to increase synthesis
Explain study of tyrosine supplementation and cognitive function trial Tyrosine supplements taken during exposure to prolonged periods of stress (1 week combat training course) appear to attenuate decrements in cognitive function
What is the effect of caffeine on dopamineenhances dopamine release. Caffeine can also directly facilitate CA2+ release in muscles.
What is the hypothesis of the effect of hypoglycaemia on central fatigue Rationale: The brain is dependent on glucose • Glucose from bloodstream is predominant energy source for the brain • Voluntary muscle activation ↓ during hypoglycaemia
What do studies on hypoglycaemia showIncreased brain activity in the hypothalamus immediately after glucose ingestion. Peak at injection time (knows glucose is arriving to system) and then 10 mins after (when it reaches brain).

Section 4

Question Answer
Glucose mouth rinse testMouth rinse of a 6.4% carbohydrate drink (CHO) or placebo during a 60min cycle time trial (TT). around 35 mins into lecture recap.
Exercise in the heat
Hyperthemia testCycling at 60% VO2max for 60 min – Hyperthermia: at 40C, to volitional exhaustion (~50 min) . After this they did a 120 second max voluntary contraction of the quadriceps. Hyperthermia group produced lower force. But if you electrically stimulate the muscles then you can restore forces to control levels, showing that it is central and not peripheral fatigue.
Which is not true: To run a marathon faster in the heat, I could….electrically stimulate the quadriceps to check the force produced ahead of the race

Section 5