Fatigue is multi factorial – what does this mean?
Good – Multifactorial means involving many factors, so when considering fatigue, this is caused by many
factors. It’s when more than one factor contributes to fatigue.
Better – Many factors contribute to fatigue, either by themselves or in combination with each other and it’s
most likely that the longer an activity goes for that multiple fatigue factors will be in play, such as fuel
depletion, elevated body temperature & associated dehydration and poor cooling techniques and
accumulation of metabolic by-products.
Comments : The better answer considers multiple fatigue factors all contributing to fatigue – a bit like
energy system interplay when all three systems contribute to ATP production, and that the longer an
activity goes for the more likely that more factors will be involved. For example, in a 100m sprint it is
likely that CP depletion will contribute to fatigue the most, but in a 400m sprint that accumulation of
metabolic by products would also have a significant contribution to fatigue. If we then extend this to
10,000m elevated body temperature will be increasing it’s effects on performance decrements.
Lots of students have difficulty explaining LIP – what is your understanding of this and how
does it contribute to fatigue (fan analogy)?
Good - LIP stands for the lactate inflection point and this occurs when H+ ions start to accumulate due to
insufficient oxygen being supplied to enable them to be broken down. When this happens they
accumulate quickly and fatigue sets in shortly after this.
Better – LIP reflects the maximum balance between lactate appearance and lactate removal from the
blood . A sudden increase occurs when the rate of lactate appearance exceeds the rate of lactate removal
and this is the point where LIP is triggered. It’s a bit like an exhaust fan in the shower. Whilst the fan
extracts steam at a faster rate than what it is being produced it will not accumulate and steam up the
shower or mirror. But, once the steam is produced at a faster rate than what it can be removed, it will
accumulate and the bathroom with steam up.
Comments : The better answer looks at the relationship between appearance and removal of lactate and
when this exceeds the removal LIP is surpassed and a rapid accumulation of hydrogen ions occurs. The
fan analogy is a good one because it considers appearance and removal of steam and what happens when
one exceeds the other.
What happens during oxygen deficit. We often hear about steady state – what does this
mean in terms of oxygen supply, energy systems and recovery during performance?
Compare oxygen consumption during deficit, steady state and EPOC
Good - Oxygen deficit occurs at the start of an activity when the anaerobic energy systems supply energy
whilst the aerobic system gradually increases it’s contribution. Steady state occurs when the aerobic
energy system takes over as the main ATP supplier and EPOC occurs during recovery when the oxygen
consumption stays above resting levels.
Better – Oxygen deficit occurs when the demand for oxygen exceeds the body’s ability to meet supply
and to meet this demand and the ATP is produced by either or both of the anaerobic energy systems. His
can occur at any stage of performance when steady state is exceeded. Steady state occurs when oxygen
supply is able to met oxygen demand and EPOC or oxygen deficit occurs once exercise has been
completed and oxygen consumption remains above resting levels – this can be increased by conducting
an active recovery.
Comments : The better answer looks at the relationship between oxygen demand and oxygen supply and
whenever demand exceeds supply oxygen deficit exists. During an activity this sees increased
contribution from the anaerobic glycolysis system. Oxygen debt or EPOC occurs during recovery whilst
oxygen consumption remains above resting levels and this period can be extended when an active
recovery is undertaken. This is advantageous in removing accumulated metabolic by-products due to the
increased presence of oxygen in the body.
How does elevated body temperature contribute to fatigue?
Good – Elevated body temperatures are associated with increased sweating and blood flow to the skin’s
surface in an effort to cool the body down. This means less oxygen flows to working muscles, and intensity
needs to decrease.
Better - As core temperature rises, sweat rates increase and blood is shunted away from muscles to the
skin’s surface causing less blood, oxygen and fuels being supplied to working muscles and may
contribute towards aerobic exercise becoming increasingly anaerobic.
Increased sweat rates cause decreases in blood plasma; to counteract this, the heart rate and cardiac
output both increase to maintain the blood supply to working muscles.
Comments : The better answer actually links blood flow away from working muscles to less oxygen and
fuels being able to get to working muscles. It also means then that the removal of metabolic by-products is
also slowed. It also considers the increased likelihood of performances becoming anaerobic due to the
decreased oxygen supply to muscles.
What is the role of sports drinks in terms of performance benefits? (performance &
recovery)
Good – Sports drinks are really important in replacing lost electrolytes which in turn can cause muscle
cramps. They are also important in helping athletes rehydrate and delay the onset of fatigue.
Better - Sports drinks allow athletes to replace fluid and electrolyte losses, and simultaneously provide an
additional source of carbohydrate fuel. They:
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prevent disruption to neural transmission
promote better fluid intake than water.
increase retention of fluid consumed post-exercise by reducing urine losses.
provide an additional source of fuel
Comment : The second answer is much more extensive and lists the benefits associated with sports drinks
rather than just stating what they contain.