| Date | November 2019 | Marks available | 1 | Reference code | 19N.3.HL:.tz0.4 |
| Level | Higher Level | Paper | Paper 3 | Time zone | time zone 0 |
| Command term | Define | Question number | 4 | Adapted from | N/A |
Question
Define hypoxia.
During a competition at altitude, a runner did not alter their normal, low-altitude hydration habits. Using the concept of fluid balance, identify reasons for the reduction in their performance at altitude.
Outline altitude training.
Using examples, predict the adaptations after endurance athletes have lived and trained at altitude for a month.
Markscheme
a condition in which the oxygen supply to cells is insufficient ✔
dehydration leads to decrease in performance ✔
ambient air at elevated altitude has lower humidity, there is a decrease in water vapour in air low humidity causes an increase in insensible water loss and dehydration✔
physical activity exacerbates this fluid loss ✔
altitude induces diuresis/increased urine production <further increasing dehydration> ✔
increased respiratory water loss ✔
increased sweat evaporation ✔
the greater need for energy increases the need for fluid intake ✔
training for athletes at altitudes above 2000 m ✔
for several weeks or months <in order to gain a competitive advantage in low altitude competitions / in order to acclimatize for competition at altitude> ✔
training where the oxygen partial pressure is low so that release of the hormone erythropoietin (EPO) can be triggered <stimulating red blood cell production> ✔
Award [1 max] for physiological adaptations.
Blood adaptations:
decreased plasma volume, associated with drier air / fluid loss ✔
increased hematocrit / increased hemoglobin concentration, associated with more EPO ✔
increased total number of RBC, associated with renal / kidney release of more EPO ✔
Muscle adaptations:
eg reduced lean body mass muscle fibre cross-sectional area decreases / loss of appetite ✔
eg increased capillary density in the muscle increases and increased oxidative capacity in the muscles so that more blood can be delivered to muscle fibres ✔
Cardiorespiratory adaptations:
eg increase in pulmonary ventilation both at rest and during exercise/VO2 max ✔
eg increase in pulmonary capillarization ✔
Accept other appropriate examples
