Physiological adaptations in response to training – Improving PDHPE
Study Notes

–Resting Heart Rate

The heart is a reliable measure of how hard the heart is working. There is a reduction in resting heart rate because of a more efficient stroke volume due to training. This is more evident in the recovery phase of training as athletes can recover faster due to the heart being stronger.

–Cardiac Output

Is the amount of blood propelled out of the heart per minute. It is worked out by the formula – Heart Rate x stroke volume. There is a rise in maximal cardiac output. A person’s cardiac output at rest is similar for a trained and untrained athlete due to extra stroke volume being offset by a decreased heart rate (trained athlete). When training at a maximal exercise intensity, a trained athlete has higher cardiac output.

–Stroke Volume

This is the amount of blood expelled by the left ventricle during a contraction (beat) There’s an increased stroke volume at rest and during the exercise. This occurs due to the heart increasing in size during training.

–Lung Capacity

This refers to the volume of air that moves in and out of the lungs during a breath. In response to training, there is a rise in maximal ventilation but lung capacity generally remains unchanged

–Haemoglobin Level

Haemoglobin is a substance that attaches to oxygen and carries it around the body. Endurance training increases haemoglobin levels, which means more oxygen carrying capability and increased performance for aerobic athletes. Therefore, in response to training, there is a rise haemoglobin levels a due to a boost in red blood cells and blood plasma numbers. Training in a high altitude environment is a temporary way to increase haemoglobin levels.

–Muscle Hypertrophy

Refers to growth in muscle as a result of training. Muscle size is generally increased with resistance training as well as gains in the size of muscle cells. The opposite to this is muscular atrophy which occurs as a result of no stimulation to the muscle.

There is an increase in muscle size after training due to increase in amount of:

Actin and myosin filament – thin protein filaments produce muscle action

Myofibrils – the elements that make up one fibre cell

Connective tissue – tissue that surrounds/supports muscles

Training needs to implement the overload principle in order to produce muscle hypertrophy. Specificity aids in targeting muscles/regions of body when hypertrophy is needed.

– Oxygen Uptake

This is the total sum of oxygen the body uses in a minute. The more oxygen the working muscles can uses in a minute during exercise, the more efficient the oxygen uptake is deemed.

Substantial improvements are seen in oxygen uptake levels as a response to aerobic training. These increases are due to a boost in myoglobin, enzyme, mitochondria and capillaries activity. Oxygen is required by Mitochondria to produce energy, which leads to higher VO2 max readings.

–Effect on Slow-Twitch Muscle Fibres (ST or Red muscle Fibres)

Slow twitch fibres are more suited to endurance events such as long distance running and swimming or cycling. In regards to training, there is an increase of hypertrophy, myoglobin content enzymes, mitochondrial function, glycogen stores and capillary supply. Slow twitch fibres can help endurance athletes resist fatigue longer as they uses oxygen effectively to help produce energy (ATP).

As a result of aerobic training we get:

– Hypertrophy of Slow twitch fibres

– Increased capillary supply to muscle fibres meaning an increase in blood supply (more oxygen to working muscles)

– Increased number/size of mitochondria (energy factory of cells) – resulting in more efficient energy production

– Increase in myoglobin content (transports oxygen from cell membrane to mitochondria).

–Effect on Fast-Twitch Muscle Fibers (FT or white muscle fibres)

These fibres contract quickly for explosive movements over a short duration. These are useful in resistance training, anaerobic events and shorter intervals. You see benefits from anaerobic training however they do fatigue rapidly. As a result of anaerobic training we see:

– Increased efficiency of ATP/PC supplies

– Hypertrophy of FT fibres

– Increased tolerance to lactic acid

– Faster/more forceful muscle contractions due to greater number of FT fibres

Full Written Notes

Critical Question 1: How does training affect performance?
Physiological Adaptations in Response to Training

Resting Heart Rate

Monitoring the heart rate is a reliable indicator of how hard the heart is working. Due to an efficient stroke volume, after training there is usually a reduction in the resting heart rate. This is more apparent during the recovery phase of training, as athletes with stronger hearts recover faster.

Stroke Volume

The stroke volume is the amount of blood ejected by the left ventricle during a contraction (beat). An increased stroke volume exists at rest and during exercise because the heart increases in size during, and due to, training.

Cardiac Output

The cardio output is the amount of blood pumped out of the heart, per minute. It is calculated using the following formula: Heart Rate x stroke volume. The cardiac output at rest is similar for both trained and untrained athletes due to the extra stroke volume being offset by a decreased heart rate (trained athlete). When training at maximum intensity, a trained athlete has higher cardiac output.

Oxygen Uptake

The uptake is the amount of oxygen the body uses in a minute and describes the ability of the working muscles to use delivered oxygen. The primary benefit of aerobic training is the increase in oxygen uptake levels. These improvements are caused a boost in the activity of myoglobin, enzyme, mitochondria and capillaries. Mitochondria uses oxygen to produce energy, leading to higher VO2 readings.

Lung Capacity

Lung capacity is a term used to describe the amount of air, which moves in and out of the lungs during a breath. Training can increase maximal ventilation but lung capacity generally stays unchanged.

Haemoglobin Level

Haemoglobin is a substance which binds to oxygen and transports it around the body. Endurance training increases haemoglobin levels, boosting red blood cells and blood plasma numbers. This means athletes are able to increase their oxygen carrying capabilities and improve their aerobic performance. Training in a high altitude environment can temporarily increase haemoglobin levels.

Muscle Hypertrophy

Muscle hypertrophy is the growth of muscle as a result of training. Resistance training can increase the size of both muscles and muscle cells. The reverse of this process is referred to as muscular atrophy and occurs when muscles are unstimulated and undeveloped.

There is an increase in muscle size after training due to increase in amount of:

– Actin and myosin filament: thin protein filaments which activate muscles
– Myofibrils: contractile elements of muscles
– Connective tissue: tissue surrounding and supporting muscle

Training plans must incorporate the overload principle in order to ensure muscle hypertrophy. Specificity is particularly important, targeting relevant muscles/regions of body which need development.

Effect on Slow-Twitch Muscle Fibers (ST or Red muscle Fibres)

Slow twitch fibres are effective in endurance events such as long distance running and swimming or cycling. When developed, there is an increase in hypertrophy, myoglobin content enzymes, mitochondrial function, glycogen stores and capillary supply. Slow twitch fibres are more efficient at using oxygen to generate fuel (ATP), creating a resistance to fatigue.

Aerobic training can result in:

– Hypertrophy of ST fibres
– Increased capillary supply to muscle fibres meaning an increase in blood supply (more oxygen to working muscles)
– Increased number/size of mitochondria (energy factory of cells) leading to more efficient energy production
– Increase in myoglobin content (oxygen travels from cell membrane to mitochondria)

Effect on Fast-Twitch Muscle Fibers (FT or white muscle fibres) –

These fibres contract quickly facilitating explosive movements over a short duration. Developing these fibres is useful for anaerobic events, short intervals and resistance training. Benefits from anaerobic training are quickly apparent but cause fatigue to set in rapidly.

Anaerobic training can result in:

– Increased efficiency of ATP/PC supplies
– Hypertrophy of FT fibres
– Increased tolerance to lactic acid
– Faster/more forceful muscle contractions due to greater number of FT fibres