App Phys week 7

bethdrysdale94's version from 2017-01-27 18:50

Section 1

Question Answer
What animals are the exceptions to streamlined swimmers?polar bears and sea otters
How do pinnipeds swim?with flippers, sea lions can reach 22mph
How do cetaceans and sirenians swim?flukes in a vertical fashion (eg dolphins)
What is special about marine mammals breathing cycle?short, fin whales can empty and refill lungs in 2 secs (1/2 the time humans take)
Why do cetaceans have an advantage?blowholes, dont have to completely surface to breathe
What is special about diving mammals physiologically?increased blood volume, increased haemoglobin, increased myoglobin (O2 storage)
What is the dive reflex?colder than 21degrees = bradycardia, blood flow to extremities is reduced, vasoconstriction offsets a drop in blood pressure
What is the neural pathway of the dive reflex?trigeminal nerve sensors around eyes and nose > vagal centres > vagal nerve > blocking of phrenic nerve
What is different about thermoregulation in water?heat is lost 5x faster than in air, helps with maintenance of homeostasis if exercising hard. limited loss of heat via sweating, due to lack of evaporation
What is the specific heat capacity of water and the vaporisation heat of water?4.1814J/(gK) at 25 degrees, and 40.65 kJ/mol at the normal boiling point - due to extensive hydrogen bonding between molecules
What is important about cold and warm water for training and competition?cold water = slower (increased viscosity) but hot water is bad for thermoregulation.
What are the limits to swim performance?Skeletal muscle, breathing, skill (motor and coordination), bouyancy (density, muscle/fat), fluid dynamics and drag
Why dont breathing adaptations help swim performance?swimming already trains diaphragm and inspiratory muscles
How much more work does it require to double speed than in air?4x more work, thus 8x amount of power; this is due to drag (friction). streamlining is therefore vital
How does drag act?opposes motion of object. drag forces act in opposite direction to oncoming flow velocity - drag forces depend on velocity
What are the old and new values of anaerobic to aerobic exercise in 50 and 100m events in swimming?old 50m: 2/98% aerobic to anaerobic and 100m 10/90% aerobic to anaerobic. NEW: 50m 30/70% 100m 40/54%
What is different about swimming techinique compared to running or cycling?swimming technique: small improvements have a large effect on performance

Section 2

Question Answer
Warm up in swimming abstractscarce studies, little is known. contradicting evidence. > warm up has positive ffect for distances greater than 200m. RECOMMENDED WARM UP; 1000-1500m, brief approach to race velocity, 8-20mins recovery to prevent fatigue and allow restoration of energy reserves
Controlled frq breath hypothesislimited breath frequency stresses system through hypercapnia and mechanical loading, may lead to improvements in respiratory muscle strength
controlled frq breath studyrandomised to either CFB or stroke matched conditions. completed 12 training sessions. CFB = 2 breaths/length and SM = 7 breaths /length.
Controlled frq breath findingsmax expiratory pressure improved by 11% in all. max inspiratory pressure was unchanged in all. running economy improved in CFB, FVC increased in SM but unchanged in CFB. CONC: limiting breath freq may improve muscular oxygen utilisation during terrestrial exercise in novice swimmers
Cardiac function and O2 sats whilst divingBreath-holding (BH) in air and immersed; LV enlargement in both BH categories. Reduced LV fraction in both categories (hinderance to diastolic filling). Haemoglobin saturation decreased less during immersed BH indicating O2 sparing effect of diving.
Responses to cold water immersioninexperienced swimmers could benefit from cold-water habituation combined with mental skills training to improve voluntary control over respiratory shock when suddenly immersed in cold water. May improve survival prospects.

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