Model Answers Flashcards
(8 cards)
Explain the difference between lactate threshold and lactate turnpoint. (5 marks)
Lactate threshold refers to the first increase of lactate concentration from resting values in a graded exercise test to exhaustion (1 mark). Intensity at lactate threshold is approximately the pace that can be sustained in a marathon (1 mark). Lactate turnpoint, on the other hand, is found at a higher exercise intensity and higher lactate values. Using the lactate curve obtained in a graded exercise test to exhaustion, it can be determined with the Dmod method, for example. It occurs at the highest exercise intensity that can be performed in homeostasis (1 mark), and hence relates to maximum lactate steady state (1 mark). Exercise intensity at lactate turnpoint corresponds to a pace that can be maintained for ~half an hour (1 mark).
How long would you have to run at an oxygen uptake of 3.0 L/min to expend 400 kcal? (2 marks)
5 kcal are expended for 1 L of oxygen taken up, therefore 15 kcal/min for 3L/min (1 mark). It therefore follows: 400 kcal / 15 kcal/min = 26.7 min (1 mark)
Immediately after a test to exhaustion on the cycle ergometer, it is good practice to keep pedalling at a light intensity. Why is this beneficial? (5 marks)
Activating leg muscles (1 mark) prevents blood pooling (1 mark). Immediately after a test leg vasculature is dilated (1 mark), therefore blood may pool. Less blood may be delivered to the brain, which may result in the participant passing out (1 mark). In addition, active recovery may help the removal of waste products / metabolites such as lactate (1 mark).
By lifting weights, will a weightlifter increase preload or afterload? Please support your answer with a brief explanation. (2 marks)
Afterload is increased (1 mark), as muscle contraction will increase resistance against which the heart has to work (1 mark).
What is the main reason that VO2max can be estimated based on rating of perceived exertion (RPE) from a submaximal incremental test (1 mark)? What is the RPE range that needs to be covered in the submaximal test so VO2max is estimated correctly (1 mark)? (2 marks in total)
There is a linear relationship of VO2 (not VO2max!) and RPE (1 mark). A range of 9-17, or 11-17 needs to be covered; if the intensity of RPE=17 is not included, then VO2max is underestimated (1 mark).
Athlete A performs a hard eccentric exercise session, Athlete B performs an equally hard concentric exercise session. Why is Athlete A more likely to suffer from muscle pain the next day? (5 marks)
Eccentric exercise is associated with higher forces than concentric exercise (1 mark), which leads to more microtrauma/damage (1 mark), including disruption of actin/myosin filaments, or Z lines (1 mark for naming at least 1 element). This leads to swelling / inflammatory responses (name at least one for 1 mark) and stimulation of pain receptors (1 mark), leading to delayed onset of muscle soreness.
A firefighter walks on a treadmill set at 5 km/h and an 8% gradient. Once this is done in sportswear, once this is done in full gear which weighs 20% of the firefighter’s body mass. For each of the following parameters, please indicate whether you expect them to decrease, remain the same, or increase. For each response, give a brief explanation. a) respiratory exchange ratio (2 marks) b) energy expenditure (2 marks) c) heart rate (2 marks
a) respiratory exchange ratio INCREASES (1 mark) (work at a higher percentage of VO2max, therefore higher reliance on carbohydrate metabolism) (1 mark) b) energy expenditure INCREASES (1 mark) as higher mass to move / higher intensity (1 mark) c) heart rate INCREASES (1 mark) as higher energy demand / higher need to deliver oxygen (or words to that effect; 1 mark) (“because work rate increased” is too generic)
Describe the negative feedback loop and the involved structures that regulate body temperature in the cold (4 marks).
Regulation by preoptic-anterior hypothalamus (1 mark) Thermoreceptors detect changes in temperature (1 mark) Results in: o Vasoconstriction (1 mark) o Shivering (1 mark) Body temperature increases Completes negative feedback loop
