7.4 Exercise

A student undertakes some moderate exercise by walking around a football pitch.

Explain what causes her heart rate to increase while she walks.

Exercise can temporarily elevate an individual’s heart rate.

Name two legal substances that may cause an individual's heart rate to increase for a period of time.

Which row of A - D gives the correct sequence of events during an expiration?

The equations below are important in biology.

CO₂ + H₂O ⇌ H₂CO₃ 

H₂CO₃ → H⁺ + HCO₃^-

(2)

The diagram below shows a spirometer, which can be used to investigate lung function before, during and after a period of exercise.

Describe how a spirometer like this one could be used to measure a person's tidal volume.

State the purpose of the soda lime shown in the diagram in part (a).

(1)

The graph below shows a partial trace. 

On the graph below, complete the spirometer trace that you expect to see recorded from a healthy sixteen year-old during ten further breaths while at rest.

(2)

An athlete's breathing was measured over 60 seconds of breathing at rest, then over 60 seconds during a period of vigorous exercise on an exercise bike. 

The athlete's body mass was measured at 75kg. 

The table below shows the results of the investigation. 

Calculate the rate of oxygen consumption by the athlete during vigorous exercise in cm³ kg^-1 min^-1.

In trained athletes, the metabolism of lactate can occur at a fast enough rate to reduce the build-up of lactic acid.

As a result, trained athletes are able to maintain a lower lactate level even during periods when their heart rate is very high, compared to an untrained individual.

A study was done to compare the blood lactate levels to the heart rate of five individuals during exercise.

Training allows an individual to maintain a low blood lactate level compared to heart rate.

Identify which is the most highly trained individual from the study.

Maximum minute ventilation (V_E) is a measure of the maximum total volume of gas inhaled or exhaled per minute (measured in L/min).

During exercise, V_E changes to accommodate changes in metabolic requirements, this variability around V_E is called V_E variability and is measured in mL/min.

Both V_E and V_E variability can be used as indicators of fitness.

The graphs below show the differences in V_E variability and maximum V_E from a study of trained and untrained individuals.

Describe the relationship between training, maximum V_E and V_E variability.

Using the information provided, assess the statement that individual 3 and individual 4 are both equally fit.

A study was carried out to show how the expression of a gene associated with lactate metabolism would influence exercise performance.

Mice were genetically modified (GM) by inserting a gene responsible for the synthesis of a protein involved in lactate metabolism, protein X.

Lactate levels in the two groups of mice were monitored throughout a period of exercise.

Compare the lactate levels of the control group to the GM group.

Public mass-participation exercise events are much promoted by governments to help maintain the general health of the population. One such example is parkrun™ (a free, weekly 5km running event); people of all ages (4 years and upwards) are encouraged to participate as runners or walkers.

The chart below shows the percentage of parkrun participants reporting certain health conditions to their doctors, grouped by their activity and typical mean finish time. 

Source: adapted from British Journal of General Practice 2022

Calculate the percentage difference between the arthritis occurrence of walkers compared to that of slower runners (42.5 - 45 minutes finish time) 

A number of the parkrunners who reported chronic pain to the doctors have benefited from receiving prosthetics, for example, a knee replacement (X-ray pictured below).

Personal Medical Records, Public domain, via Wikimedia Commons

Part of their post-operative recuperation can involve an exercise program like a 5km parkrun/walk.

Outline the benefits of prostheses to parkrunners like these.

X-rays like that in part (b) can be used to assess damage to the cruciate ligament, one of the important ligaments that stabilise the knee. 

Outline the way in which a damaged cruciate ligament can be fixed surgically. 

Comment on the relationship between the incidence of arthritis in parkrunners/walkers and their mean finishing times.

A copy of the graph from part (a) has been repeated below: