Identify three reasons why athletes who overtrain may be more susceptible to infection.

Explain the differences in dietary recommendations for a runner during marathon training and a sedentary individual both with healthy body mass index (BMI).

Explain how the hypothalamus regulates the pituitary gland.

Outline the nervous control and mechanics of inspiration during exercise.

lower leucocyte numbers <caused by the stress of exercise>;

inflammation caused by muscle damage;

greater exposure to airborne bacteria and viruses <because of an increased rate and depth of breathing>;

Marathon runner:
use more calories <than sedentary individuals> and therefore are recommended to have a higher calorie intake/ energy intake;

has a high training volume and therefore have a much higher recommendation for carbohydrate intake;

need some fat stores and are recommended a <slight> increase in fat consumption;

need to recover after activity and are recommended a <slightly> higher protein intake;

thermoregulate more and are recommended to have a higher water/ electrolyte intake;

greater mineral and vitamin intake for bone strength/blood cell production/growth;

Accept in the converse.

hypothalamus receives feedback from the body regarding homeostasis;

pituitary and hypothalamus are endocrine organs;

pituitary gland is located <in the brain> below the hypothalamus for efficiency of regulation;

hypothalamus regulates the pituitary gland to maintain homeostasis/growth/water balance/reproduction/temperature;

neurohormones <such as GHRH and somatostatin from the hypothalamus> directly influence the pituitary gland;

nerve impulses from the hypothalamus stimulate the pituitary gland;

regulatory/neurohormones are delivered through the portal/blood vessel;

pituitary gland <posterior lobe> secretes hormones e.g. antidiuretic hormone (ADH) <into surrounding capillaries>
OR
pituitary gland <anterior lobe> secretes hormones e.g. growth hormone (GH)/ luteinizing hormone (LH) <into surrounding capillaries>;

Award [2] if candidate accurately identifies specific lobes for pituitary gland and correct hormone NFP.

nervous control:
increase in acidity/CO₂ concentration is detected by <chemo>receptors;

<proprio>receptors detect an increase in muscle movement;

receptors inform the brain/respiratory centre;

the brain/medulla oblongata stimulates/sends nervous signals the inspiratory muscles to contract;

nerve impulses are sent via the sympathetic nervous system <phrenic nerve>;

nerve impulses stimulates an increase in the depth of breathing;

mechanics:
external intercostal muscles contract more forcefully;

ribs move upwards and outwards further;

diaphragm contracts and flattens;

thoracic cavity volume increases further;

pressure gradient of thoracic cavity with atmosphere increases
OR
thoracic cavity pressure decreases further;

more air rushes into the lungs;

strenuous exercise stimulates the use of accessory muscles <scalenes, sternocleidomastoid & pectoralis minor>;

Award [4 max] for each nervous control and mechanics.

Must be reference to mechanics during exercise compared to rest in order to credit mark.

Award [1 max] for accurate mechanics of inspiration but with no reference to changes caused by exercise.

Candidates answered this question confidently and demonstrated good levels of knowledge for this topic area.

Many candidates were able to identify the differences in the dietary requirements between the marathon runner and sedentary individual, although they commonly focused on the macronutrients. Several candidates failed to explain the reason for the differences and struggled to access the marks available.

Candidates had a good level of knowledge for this question, but struggled to access marks beyond mark points 4, 5 & 8 of the markscheme.

Candidates had a general understanding of chemical control of breathing. Many had a limited knowledge of the link between respiratory control and inspiration and expiration. Candidates showed a good level of knowledge regarding the mechanics of breathing, although further review of this area would be beneficial. However, very few candidates made the link to the effect of exercise on the breathing mechanics.