Explain why elite athletes are generally more susceptible to infection than sedentary individuals.

Explain how a complex feedback loop regulates blood glucose.

Explain the phenomenon of cardiovascular drift and one method of reducing it.

A table-tennis ball is hit with topspin. Apply the Bernoulli principle to the projectile motion of the ball.

The diagram shows a tennis player serving.

Explain how a coach would use both the phase analysis model and the performance outcome model to teach the tennis serve.

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

regular heavy training loads performed by elite athletes can lead to a rise in cortisol levels / reduction in adrenaline levels;

high levels of stress hormones reduce leucocyte numbers therefore reducing the ability to fight infection when exposed;

inflammatory response to muscle damage can become overactive due to stress hormones / levels of training;

high levels of stress hormones can cause an overactive or <severely> suppress inflammation in response to infection;

Do not accept ‘low leucocytes’ or ‘inflammation’ alone.

a <negative> feedback loop counteracts a change to return blood glucose levels to an acceptable level for the body;

receptors in the pancreas detect changes in blood glucose;

elevated blood glucose levels stimulate the release of insulin <by the pancreas>

OR

lower blood glucose levels inhibit release of insulin <by the pancreas>;

insulin stimulates glucose uptake/promotes glycogenesis to lower blood sugar levels;

lower blood glucose levels stimulate the release of glucagon <by the pancreas>

OR

elevated blood glucose levels inhibit release of glucagon;

glucagon stimulates glycogenolysis to increase blood sugar levels;

Max [2] if no reference to high or low blood sugar levels only.

Phenomenon

occurs during prolonged submaximal exercise;

reduction in blood volume due to sweating

OR

reduction in blood volume leads to increase blood viscosity;

reduced blood volume results in decrease in stroke volume;

heart rate increases to maintain cardiac output;

vasodilation causes a reduction of blood flow to working muscles;

Prevention

maintain hydration to maintain blood viscosity;

decrease exercise intensity;

exercise during cooler part of day;

wear clothing which allows air flow;

Max [4] for phenomenon.

Max [1] for prevention.

action of rotation causes the air to be dragged around the rotation of the ball;

this causes increased air velocity underneath the ball and a decreased air velocity on the top;

there is an inverse relationship between air flow velocity and air pressure which is expressed in the Bernoulli principle;

resulting in a high pressure area on the top and a low pressure on the bottom of the ball;

the ball will move towards the low pressure area / downwards;

the ball will drop on to the table sooner <than with either no spin or backspin> / reduce the distance the ball travels before hitting the table;

Accept marking points as annotations on a diagram.

Phase analysis model:

the coach can use this model to divide up the serve <sequentially> so that attention can be focused on the performance of each part;

coaches can use video analysis to isolate phases of the serve and identify specific areas for improvement;

the coach can break down the skill into preparation, retraction, action and follow through;

e.g. preparation: positioning body/stance;

e.g. retraction: backswing and ball toss;

e.g. action: execution of hitting the ball;

e.g. follow-through: continuation of action after contact;

Performance outcome model:

the <hierarchical> model can be used to identify mechanical factors that contribute to the execution of the serve,

these are speed, force, coordination and <specific performance> principles;

coaches can focus on mechanical factors in isolation to assist the overall performance of the serve;

e.g. speed principles: whole body speed vs body part/racket speed, e.g. flexing the racket head to generate racket head speed;

e.g. force principles: summation of forces, e.g. good knee bend to generate force;

e.g. coordination principles: biomechanically efficient timing of each action;

e.g. specific performance principles: e.g. poor position of ball toss affecting accuracy/placement

Max [4] for each of the models.

Accept appropriate examples for performance improvement.

Accept appropriate annotated diagram.

Candidates clearly have a good basic knowledge of this topic, however their knowledge appears to be quite superficial and candidates struggled to provide more detail other than a list of factors which raise an elite athlete's susceptibility to infection. Candidates need to have a greater understanding of these factors. Typically, candidates were able to access marks related to greater exposure to airborne bacteria and viruses due to their depth of breathing. Some understand the rise in stress hormones suppressed the immune system and impacted leucocyte levels. Few were able to truly explain inflammation.

Candidates fared well on this question, they were able to link the appropriate glucose level with the response of the pancreas and the effect of the corresponding hormone. However, it did appear to be an area where candidates either had a sound understanding or no understanding.

Of the candidates who chose question 11, a number did not choose to answer this question. This was another question raised by the G2 forms. Overall candidates approached this question very well. They were able to explain the effect of sweating on blood viscosity and the impact this had on stroke volume, cardiac output and heart rate respectively. Nearly all candidates were able to identify a method to reduce the effect of cardiovascular drift, with the most popular response being to maintain hydration. However, some candidates need further review of when cardiovascular drift may occur.

Similar to question 11c, a number of the candidates who selected question 11, chose not to answer this question.

Many of the candidates were able to correctly identify the difference in air velocity and therefore air pressure. With the majority identifying the impact that this had on the flight of the ball. Although many candidates were able to understand the requirements of the question there were a number who were confused and started to discuss back spin. With many referring to back spin in their answer. Therefore, reading through the question and reviewing their answers is always encouraged.

Many candidates had a good understanding of phase analysis model and were able to describe the model and apply it effectively to tennis. This is where most of the credit was awarded. However, with regards to performance outcome model, candidates may have been able to outline the model but really struggled to apply it and therefore this requires particular attention. Candidates misunderstood the concept of the principles and how they would be applied by a coach.