Transcript LIP Lactate inflection point

LIP
LACTATE 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.
LACTAT
E
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
Key Knowledge
• 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 Skills
• 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.