LIPLACTATE INFLECTION POINT

LIP• When we exercising using

the anaerobic systems (either immediately when we start exercising or when we are working at high intensity) a large amounts of lactate is released and accumulates

• When 02 consumption doesn’t meet the 02 demand, lactate accumulates in the muscles

LIP• When it O2 consumption = 02 demand it is called the

Steady State (which is indicated by a plateau in 02 consumption)

• At this point lactate is produced and removed at the same time

• The last point this occurs is the LIP (Lactate inflection point)

• After the LIP, the body is unable to clear lactate at the same rate as being produced, so it accumulates, which equals fatigue

LIP• At exercise intensities beyond the LIP blood lactic acid concentration increases

• Beyond the LIP the athlete has to stop or reduce muscle effort

• Trained athletes can and aim to increase their tolerance to lactic acid accumulation

• Scientific testing in labs (eg: AIS) is the best method, but a rough estimates describes it as• Untrained athlete ~60% max HR• Trained athlete ~90% max HR

LIP

Lactate• Lactate is continuously being produced by our body• As exercise intensity increases, so does lactate

production

Lactate inflection point (LIP)• Individuals with a greater proportion of slow twitch fibres

relative to fast twitch fibres have a greater ability to oxidise fatty acids in mitochondria, and in turn will have a higher LIP.

Lactate inflection point (LIP)• LIP tests provide guidance as to the training intensity

required to improve endurance performance and predict the speed or power output an athlete is able to sustain for a prolonged period of time.

• In events exceeding 10–15 minutes duration, the relative importance of LIP to endurance performance increases.

• Research indicates that LIP is frequently a better predictor of performance than VO2 max. in events of extended duration.

Lactate inflection point (LIP)• An individual’s LIP can be raised by regular endurance

training. • Training near the LIP is an adequate training stimulus for

an untrained individual, but a higher intensity is necessary for endurance-trained athletes.

• Most of the improvements in the LIP progressively occur over 8 to 12 weeks of training, but small changes may accrue beyond this period.

Lactate inflection point (LIP)• An individual’s LIP varies depending on their training

status. • LIP in untrained individuals typically occurs between 55 to

70% of VO2 max. • In well-trained individuals the LIP typically occurs between

75–90% of VO2 max.

Lactate inflection point (LIP)• Therefore with appropriate training the lactate inflection

training point will occur at higher intensity in a more trained versus untrained athlete.

Lactate inflection point (LIP)• The adaptations that lead to an improvement in the LIP

are localised to the specific muscle cells used in chronic exercise training.

• Greater mitochondria mass and an increased capability to oxidise fat and carbohydrate in response to endurance training and lead to an improvement in LIP.

Lactate inflection point (LIP)

So VCAA says you need to know• define the term LIP • identify the LIP on a graph • understand why lactate accumulates beyond LIP• describe the impact of exercise intensities beyond LIP on

fatigue • identify the differences in LIP between a trained and an

untrained athlete • describe how training can improve LIP.

LACTATE

Lactate• Lactate is now seen as an important metabolic substance• It acts as a fuel source for aerobic metabolism• Any lactate that is produced within the muscle cell will be

shuttled (or moved) between the muscle and the blood stream.

Lactate• Lactate is produced from glycolysis (ATP is also

produced)• When there is sufficient 02 pyruvic acid enters the

mitochondria for aerobic energy to be produced• When there is insufficient 02, pyruvic acid becomes

lactic acid• LA disassociates and we are left with H+ions and lactate

Lactate• We know that when H+ions accumulate that cause

muscle acidosis occurs and reduces the bodies ability to produce ATP via glycolysis and inhibit muscle contraction

• So NAD+ removes the H+ions• The NAD+ becomes NADH and transports the H+ions to

the mitochondria gate, where they combine with H20• Without sufficient 02 the NADH can not release the

H+ions and so they accumulate

Lactate• To combat this rise in acidity … some H+ions combine

with pyruvic acid to form lactic acid• This lactic acid again breaks down to lactate and H+ions• Some of this lactate diffuses into the blood and takes

some H+ions with it.• This reduces the amount of H+ions in the muscle cell,

decreasing acidity•

Lactate • Lactate production does not cause an increase in H+ions• BUT … it is a good indicator as it coincides (or happens at

the same time) as an increase in H+ions and therefore is a good indicator of fatigue

• Lactate production can actually assist delay fatigue as it can move the H+ions away from the muscle cells and to the blood stream

Lactate • Training can improve the bodies ability to clear lactate

from the muscle• However, blood acidosis can also cause fatigue as it can

impair the CNS

SIMPLY• Glycolysis occurs and pyruvate is formed• Insufficient 02 leads to lactate and H+ions• Lactate and H+ions from the muscle are transported to

the blood, lowering muscle acidosis• Lactate that is left in the muscle tissue either breaks down

producing ATP or via the cori cycle creates more glycogen for future ATP production

• http://www.youtube.com/watch?v=XvIICKaHbKQ

THE ALL OR NOTHING PRINCIPLE

The All or Nothing principle• That is a motor unit either contracts fully or it does not

contract• To increase the amount of force able to be produced, your

body either increases the number of motor units recruited or it increases the frequency of messages sent to activate the motor unit

• Less motor units recruited = less force (but all muscle fibres contract fully)

• More motor units recruited = greater force (and still all muscle fibres contracted fully, but there are more motor neurons stimulated to contract more muscle fibres)

The All or Nothing principle

The All or Nothing principle

The All or Nothing principle

The All or Nothing principle

• Mechanisms responsible for the acute responses to exercise in the cardiovascular system.

• Mechanisms responsible for the acute responses to exercise in the respiratory system.

• Mechanisms responsible for the acute responses to exercise in the muscular system.

Key Knowledge

• Participate in physical activities to collect and analyse data relating to the range of acute effects that physical activity has on the cardiovascular, respiratory and muscular system of the body.

Key Skills