Q11 - Glycemic Index and Metabolic Response During Exercise

Theoretical B Real exam question - full text reproduced under IBO's CC BY-NC-SA 4.0 license

The effect of consuming foods, which varied in their glycemic index (GI), on prolonged exercise were studied. GI expresses the effect of a particular type of food on a person’s blood glucose level. At start of test, each person either got 1) Control, i.e. water (black squares); 2) LGI, i.e. a low GI meal + water (blue triangles), or 3) HGI, i.e. a high GI meal + water (red circles). Afterwards, each person rested, then cycled for 1 hr at 65% of her VO₂max, and finally at 90% VO₂max until exhaustion. Blood samples were taken before and during tests to measure levels of lactate, glucose and insulin (Fig.).

Levels of lactate A), glucose (B) and insulin in blood (C) before (pre-exercise) and during test. Each curve represents a treatment (red circles: high GI, blue triangles: low GI, black squares: control) (from Jamurtas et al. 2011).

Figure 1. Figure 1.

Using the information and data, determine which of the statements are true or which are false.

A. At the time of exhaustion, O₂ uptake was sufficient for complete metabolism

B. The level of lactate in the blood during exercise is influenced by the diet

C. Final test result at the time of exhaustion seems to be significantly affected by the kind of diet

D. The observed increase in blood glucose at the last phase of 90% VO₂max is due to an increase in fat metabolism and a reduced use of glucose

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Question reproduced from IBO 2015, Theoretical Exam B, licensed under CC BY-NC-SA 4.0 - attributed to the International Biology Olympiad. Open the full exam PDF · Community solutions (unofficial)