Chemistry and sport
General Health and Physique
Sugar - the toxic truth
comment in the magazine Nature (2 February 2012, Vol 482, pps 27-29)
by Lustig and colleagues, highlights the changing concern of sugar in food.
The comments that follow are instructive as well!
Improvement in records - due to equipment or health?
According to a report by
In many athletic events, very little of the
overall improvement in the past 100 years has been due to innovation in
the design of sports equipment or the materials used. The main causes of
improvement are socio-economic factors such as increased leisure time,
increased professionalism of sport, state-supported sports systems, and
the increased participation rate of women. Some of the improvement in
performance may be due to better coaching and training methods, particularly
in strength training and cardiovascular training, and advances in sports
medicine that have prolonged athletic careers. In most cases there were
temporary declines in performance due to World War I and World War II.
In some events, particularly for women, there was a noticeable decline
in performance starting in 1989. This was due to the demise of the organised
sports systems in the Eastern European nations and the more expansive
drug testing programs that were introduced following the disqualification
of Ben Johnson at the 1988 Olympic Games.
Height can play a significant role in contributing to success in some sports
by offering certain natural advantages. For those sports where this could
be a contributing factor, height can be useful (although certainly not
in all cases, and is not the only factor) since in general it affects
the leverage between muscle volume and bones towards greater speed of
movement and power, depending on overall build, fitness and individual
ability. However, there can also be significant disadvantages posed
by size and resultant mass that could prove to be a hindrance to
success. Finally, there are numerous sports where size may be irrelevant.
Taller players have an advantage in basketball because their shots have
less distance to travel to the basket; they start out closer to the rebound;
and their ability to reach higher into the air yields a better chance of
blocking shorter players' shots.
In college and professional basketball, even the shortest players are
usually above the average in height compared to the general population.
In men's professional basketball, the guards, the smallest players, are
usually around 1.83 m (6 ft 0 in) to 1.91 m (6 ft 3 in), the average height
for basketball players is about 2.01 m (6 ft 7 in) and the centers, the
tallest players, are generally from 2.08 m (6 ft 10 in) to 2.18 m (7 ft 2 in).
In cricket, some of the great batsmen like Donald Bradman 1.70 m (5 ft 7 in),
Sachin Tendulkar 1.65 m (5 ft 5 in) and Sunil Gavaskar 1.63 m (5 ft 4 in)
are or were below average height. This may be because a smaller body makes
for an advantage in footwork and balance. Similarly, the most graceful
wicket-keepers have tended to be average height or below. Although there
are fewer tall batsmen, the stand-outs are often noted for their heavy
hitting and an ability to get a long stride forward to reach a full length
delivery. Chris Gayle at 1.91 m (6 ft 3 in) is a modern example
of a powerful, tall batsman. Past greats like Clive Lloyd and Graeme Pollock
were above 1.80 m (5 ft 11 in).
On the other hand, many of the most successful fast bowlers have been
well above average height; for example past greats Joel Garner,
Courtney Walsh, and Curtly Ambrose were all approximately 2.00 m
(6 ft 6 1/2 in) tall. Similarly, Glenn McGrath, regarded as one of the
finest bowlers to play the game, was 1.95 m (6 ft 5 in) tall, well above
average height. Taller bowlers have access to a higher point of release,
making it easier for them to make the ball bounce uncomfortably for a
batsman. For extreme pace however, bowlers tend to be closer to average
height. The fastest modern bowlers have ranged from Lasith Malinga 1.68 m
(5 ft 6 in) through to Dilhara Fernando at 1.90 m (6 ft 3 in), and
Steve Harmison and Shaun Tait at 1.93 m (6 ft 4 in).
Current Australian left-arm fast bowler Mitchell Johnson is 1.89 m (6 ft 2 in).
Height does not appear to be an advantage to spin bowling and few
international spinners are ever much taller than 1.80 m (5 ft 11 in).
Tall spin bowlers like Sulieman Benn, 2.01 m (6 ft 7 in) use extra
pace and bounce, whereas spin is traditionally about using a looping,
plunging trajectory at slow (70-90 km/h or 40-60 mph) speeds. The most
successful bowlers ever in Test cricket, Muttiah Muralitharan and
Shane Warne are 1.70 m (5 ft 7 in) and 1.83 m (6 ft 0 in) respectively.
Height is generally considered advantageous in swimming. Taller swimmers
with longer arms are able to achieve better leverage, hence more acceleration,
in the water. And water resistance goes down with increasing height.
This is especially true for freestyle. An example of a tall swimmer is
Michael Phelps, at 1.93 m (6 ft 4 in) who won eight gold medals at the
2008 Olympic Games and clocked up another set at the 2012 Olympic Ganes in London.
Ian Thorpe is 1.95 m (6 ft 5 in).
The average height of the eight finalists in the
100 meter Freestyle final at the 2008 US Olympic Trials was 1.96 m (6 ft 5 in).
A survey conducted in Spanish Town during 1994-1996 of 520 men and 776 women
aged between 25 and 74 found that the average height for men was
1.72 m (5 ft 7 1/2 in) and for women was 1.61 m (5 ft 3 1/2 in).
Waist size was found to be
positively correlated with blood pressure and fasting blood glucose with
men's waists measured at 80.9 cm and for women 83.4 cm. There was a 10-fold
elevated risk for diabetes type 2 for men between the lowest and highest
quartiles of waist circumference.
All physical and mental activity requires a source of energy and
this is normally provided by the digestion and processing of our food into
chemical energy. Metabolic processes that use
adenosine triphosphate (ATP) as an energy
source convert it back into its precursors. ATP is therefore continuously
recycled in organisms: the human body, which on average contains only 250 g
of ATP, turns over its own body weight in ATP each day, i.e is recycled about
every five minutes!
Here ADP and AMP are adenosine diphosphate and adenosine monophosphate.
The amount of ATP stored in muscle is limited, typically lasting only
the first few seconds in a sprint, so the body must continually replenish
its store of ATP. Three energy systems are available for this.
- ATP + H2O ↔ ADP + Pi ΔG° = -30.5 kJ/mol
- ATP + H2O ↔ AMP + PPi ΔG° = -45.6 kJ/mol
Primary Energy Sources
- the phosphagen system - anaerobic process
- fast glycolysis - anaerobic oxidation
- slow glycolysis - aerobic oxidation
||Level of Intensity
||Primary Energy System
||< 6 s
||ATP-PC and Fast Glycolysis
||30 s - 2 min
||Fast and Slow Glycolysis
||Slow Glycolysis and Oxidative
||> 30 min
Phosphagen (ATP-PC) System
Exercise that lasts for less than six seconds and is of high
intensity utilises this system. The phosphagen system contains three
basic reactions that are used in the production of ATP.
The first of these is the reverse of the first reaction shown above.
The other reactions needed to maintain ATP availability and replenish
the ATP stores in skeletal muscle include the following:
In the reaction above the ATP is resynthesised from ADP and creatine phosphate
(CP), also called phosphocreatine (PCr), such that phosphate is
released from CP and combined with ADP to make ATP.
- Enzyme: Creatine Kinase
- ADP + CP ↔ ATP + Creatine
A third reaction involves conversion of 2 molecules of
ADP into AMP and ATP. The P released from 1 ADP
can recombine with another ADP, resulting in the reformation of ATP.
Glycolytic System (Glycolysis)
- 2ADP ↔ ATP + AMP
Glycolysis is the breakdown of carbohydrates, either glycogen stored
in the muscles or glucose delivered via the blood, to pyruvate.
The pyruvate thus formed may react via two pathways depending on
the intensity and duration of exercise.
- Anaerobic (fast) glycolysis is where the pyruvate formed is converted to lactate.
- Aerobic (slow) glycolysis is where the pyruvate is oxidised to carbon dioxide.
ATP resynthesis occurs at a faster rate, but is limited in
duration. Fast glycolysis can be summarized as follows:
When glycolysis occurs at a very rapid rate there is the possibility that
lactate and H+ can accumulate and this has been linked to
fatigue and ultimately a cessation of activity.
- Glucose + 2P +2ADP ↔ 2 Lactate + 2ATP + H2O
Slow Glycolysis and the Oxidative Phosphorylation system
In most conditions,
anaerobic metabolism occurs simultaneously with
because the less efficient anaerobic metabolism must supplement
the aerobic system due to energy demands that exceed the aerobic system's
capacity. What is generally called aerobic exercise might be better termed
"solely aerobic", because it is designed to be low-intensity enough not to
generate lactate via pyruvate fermentation, so that all carbohydrate is
aerobically turned into energy.
Initially during increased exertion, muscle glycogen is broken down to
produce glucose, which undergoes
producing pyruvate which then reacts with oxygen via the
tricarboxylic acid (TCA) cycle [otherwise called the
Krebs or citric acid cycle], to produce carbon dioxide and water and
releasing energy. If there is a shortage of oxygen (anaerobic exercise,
explosive movements), carbohydrate is consumed more rapidly because the
pyruvate ferments into lactate.
Carbon dioxide, water and ATP are the final products.
- Glucose + 2P + 2ADP + 2NAD+ ↔ 2Pyruvate + 2ATP + 2NADH + 2H2O
- glucose + 6 O2 + 38 ADP + 38 phosphate ↔ 6 CO2 + 6 H2O + 38 ATP
As carbohydrates deplete, fat metabolism is increased so that it can
fuel the aerobic pathways. The latter is a slow process, and is accompanied
by a decline in performance level. This gradual switch to fat as fuel is a
major cause of what marathon runners call "hitting the wall". Anaerobic
exercise, in contrast, refers to the initial phase of exercise, or to any
short burst of intense exertion, in which the glycogen or sugar is respired
without oxygen, and is a far less efficient process. Operating anaerobically,
an untrained 400 meter sprinter may "hit the wall" short of the full
The aerobic system will begin to utilise
(fat) once the glycogen stores are exhausted, after approximately
25 minutes of continuous activity.
A heavy training session can deplete carbohydrate stores in the
muscles and liver, as can a restriction in dietary intake.
Carbohydrate can release energy much more quickly than fat so are used
for short sharp bursts of activity.
Note that based on the energy release figures it means that if the human
body relied solely on carbohydrates to store energy, then a person would
need to carry 31 kg (67.5 lb) of hydrated glycogen to have the energy
equivalent of 5 kg (10 lb) of fat.
Implications of Blood Lactate levels
Resting blood lactate concentrations are generally < 2 mmol/L, but as we
exercise concentrations steadily increase. As we become more
accustomed to interval training our muscles become more tolerant
to lactate and we can work for longer periods.
Lactate threshold (LT) is the first workload at which there is a
sustained increase in blood lactate concentration above resting
levels. There is an approximately 1 mmol/L rise from resting levels.
Anaerobic threshold (AT) or sometimes referred to as onset of
blood lactate accumulation (OBLA) is defined as the workload
causing a rapid rise in blood lactate indicating the upper limit
of production and clearance. Blood lactate concentrations at AT
are approximately 4 mmol/L.
If an athletes lactate levels were tested in week 1, then again after training
in week 12, we would expect the curve to have shifted to the right, indicating:
Among the recognized benefits of doing regular aerobic exercise are:
- Higher power output at the anaerobic threshold.
- Higher oxygen consumption throughout and in particular at the anaerobic threshold.
- Heart rate reduction at the same power output as week one.
Their cardiovascular system (heart and lungs) would not be working as
hard at the same power output as week one.
- Performance level enhancement.
- Improved lactate tolerance.
As a result, aerobic exercise can reduce the risk of death due to
cardiovascular problems. In addition, high-impact aerobic activities
(such as jogging or using a skipping rope) can stimulate bone growth, as
well as reduce the risk of
both men and women.
- Strengthening the muscles involved in respiration, to facilitate the
flow of air in and out of the lungs
- Strengthening and enlarging the heart muscle, to improve its pumping
efficiency and reduce the resting heart rate, known as
- Strengthening muscles throughout the body
- Improving circulation efficiency and reducing blood pressure
- Increasing the total number of red blood cells in the body, facilitating transport of oxygen
- Improved mental health, including reducing stress and lowering the incidence of depression
- Reducing the risk for diabetes.
- Burns body fat, while building leaner muscle.
In addition to the health benefits of aerobic exercise, there are numerous
- Increased storage of energy molecules such as fats and carbohydrates
within the muscles, allowing for increased endurance
of the muscle sarcomeres to increase blood flow through the muscles
- Increasing speed at which aerobic metabolism is activated within muscles,
allowing a greater portion of energy for intense exercise to be generated
- Improving the ability of muscles to use fats during exercise,
- Enhancing the speed at which muscles recover from high intensity exercise
Which drink is better when it comes to rehydrating during or after exercise?
Should you choose water, coffee or tea perhaps? Maybe juice or carbonated drinks
are best? And what is it about sports drinks that make them so effective?
Chemists have determined the answer to all of these questions.
Sports drinks can be characterised as:
Most sports drinks are moderately isotonic, having 13 and 19 gram of
sugar per 250 ml serving.
- Isotonic - contain similar concentrations of salt and sugar as in the human body.
- Hypertonic - contain a higher concentration of salt and sugar than the human body.
- Hypotonic - contain a lower concentration of salt and sugar than the human body.
Examples of sports drinks include:
Coconut water has being marketed as a natural sports drink because of its
high potassium (> 220 mg/100 g) and mineral content. In addition it
contains antioxidants linked to a variety of health benefits. Cytokinins such as
in coconut water may be among its most beneficial components.
Kinetin has been suggested
as having a strong anti-ageing effect on
human skin cells and skin care products containing kinetin have
been developed to treat photo-damaged skin.
Unless the coconut has been damaged, it is likely sterile. There have been
cases where coconut water has been used as an intravenous hydration fluid
in some developing countries where medical saline was unavailable.
Note as well a study from the St Augustine campus of UWI,
on coconut water/mauby for hypertension
Liz Applegate, director of sports nutrition at UC Davis commented on the use of
coconut water after strenuous activity
Coconut water contains the electrolytes sodium, potassium, magnesium, calcium
and phosphate as well as small amounts of many essential amino acids. That
roster of minerals has made it popular among fitness junkies looking for a
natural alternative to sports drinks without artificial colors or
preservatives, Applegate said.
Gatorade, Lucozade, OK, but what about
But though coconut water is fine for "the typical working-out person,"
she says, it's not for athletes engaged in intensive training, because
compared with some commercial sports drinks, it is low in carbohydrates
and sodium, which are essential for recovery following hard-core training.
Coconut water contains very little protein, which is crucial in a
true recovery drink, says Becci Twombley, director of sports nutrition at
UCLA. She says that after a hard workout, adults need at least 15 to
17 grams of protein; 8 ounces of coconut water contains less than 2 grams
of protein, according to an analysis that Singaporean researchers
published in 2009.
On the other hand, coconut water contains up to 15 times as much
potassium as the average sports drink. Like sodium, potassium is a
key electrolyte that gets sweated out during exercise. But because
the body loses more sodium than potassium during a workout, all that
extra potassium isn't necessarily important in a sports drink, Applegate
says. (There's certainly no harm in it either, she adds.)
A few small studies by researchers in Malaysia suggest that coconut water
can rehydrate the body about as reliably as a sports drink and perhaps a
little better than plain water. In one study, eight men exercised in the
heat until they lost about 3% of their body weight and then drank either
coconut water, plain water or a sports drink to rehydrate.
All three beverages replenished the men equally.
In a second study, 10 men who exercised in the heat for 90 minutes drank
either water, a sports drink, coconut water or coconut water plus sodium.
After two hours, those who drank the sports drink and coconut waters were
slightly more rehydrated - measured by the amount of body weight they
regained - than those who drank the pure water. That makes sense, says
Twombley, since electrolytes in the sports drink and coconut water would
facilitate the body's water uptake. The study was published in the
Southeast Asian Journal of Tropical Medicine and Public Health.
It has been found that the resynthesis of glycogen between training sessions
occurs most rapidly if carbohydrates (CHO) are consumed within 30 min to 1 h
after exercise. Indeed, delaying carbohydrate ingestion for 2 h after a
workout can reduce the rate of glycogen resynthesis by as much as half.
In addition to replenishing the carbohydrates lost during intensive exercise
and correcting any sodium imbalance, it has been found that addition of protein
(at a carbohydrate-to-protein ratio of 2 to 2.9:1) can hasten the rate of
glycogen synthesis and improve endurance recovery.
International Journal of Sport Nutrition and Exercise Metabolism, 2006, 16, 78-91.
In this study nine male, endurance-trained cyclists performed an interval
workout followed by 4 h of recovery, and a subsequent endurance trial to
exhaustion at 70% VO2max, on three separate days.
Immediately following the first exercise bout and 2 h of
recovery, subjects drank isovolumic amounts of chocolate milk, fluid replacement
drink (FR), or carbohydrate replacement drink (CR), in a single-blind, randomized
design. Carbohydrate content was equivalent for chocolate milk and CR.
The time to exhaustion (TTE), average heart rate (HR), rating of perceived
exertion (RPE), and total work (WT) for the endurance exercise were compared
between trials. TTE and WT were significantly greater for chocolate milk
and FR trials compared to the CR trials. The results of this study suggest
that chocolate milk is an effective recovery aid between two exhausting
Here FR was Gatorade, CR was Endurox R4 and the chocolate milk was a
low-fat product from The Kroger Co.
in sports drinks.
Taurine, or 2-aminoethanesulfonic acid, is a major constituent of bile and
can be found in the large intestine and in the tissues of many animals,
including humans. Taurine has a ubiquitous distribution and accounts for
approximately 0.1% of total body weight.
The determination of taurine in sports drinks using HPLC was the
subject of the
J Chem Educ., 2001 (78), 191
laboratory exercise article.
Despite being present in many energy drinks and dietary supplements,
and being a required nutrient for some animals, taurine has not been shown
to beneficial in human nutrition. A study of mice hereditarily unable to
transport taurine suggests that it is needed for proper maintenance and
functioning of skeletal muscles. In addition, it has been shown to be
effective in removing fatty liver deposits in rats, preventing liver
disease, and reducing cirrhosis in tested animals. There is also evidence
that taurine is beneficial for adult human blood pressure and possibly,
the alleviation of other cardiovascular ailments (in humans suffering
essential hypertension, taurine supplementation resulted in measurable
decreases in blood pressure).
Taurine is regularly used as an ingredient in energy drinks, with many
containing 1000 mg per serving, and some as much as 2000 mg.
A 2003 study by the European Food Safety Authority found no adverse
effects for up to 1,000 mg of taurine per kilogram of body weight per day.
A review published in 2008 found no documented reports of negative
or positive health effects associated with the amount of taurine used
in energy drinks, concluding that "The amounts of guarana, taurine,
and ginseng found in popular energy drinks are far below the amounts
expected to deliver either therapeutic benefits or adverse events".
In 1993, approximately 5,000 - 6,000 tons of taurine were produced for
commercial purposes; 50% for pet food manufacture, 50% in pharmaceutical
applications. As of 2010, China alone has more than 40 manufacturers
of taurine. Most of these enterprises employ ethanolamine as starting material
to produce a total annual production of about 3,000 tons.
Death by water.
Consumption of excessive amounts of water can cause water intoxication,
a potentially fatal imbalance of electrolytes in the body.
Water intoxication is fortunately extremely rare. It has occurred,
for example, during intense exercise when heavy sweating removes water
and electrolytes from the body, and large quantities of water were
consumed to replace what had been lost. The resulting low concentration
of electrolytes adversely affected the central nervous system function.
This can lead to a condition called
that may result in death.
Creatine - the Power Supplement
Creatine is a nitrogenous organic acid that occurs naturally in
vertebrates and helps to supply energy to all cells in the body,
primarily muscle. This is achieved by increasing the formation of
Adenosine triphosphate (ATP).
Creatine supplements are sometimes used by athletes, bodybuilders,
wrestlers, sprinters and others who wish to gain muscle mass, typically
consuming 2 to 3 times the amount that could be obtained from a
very-high-protein diet. A survey of long-term use gives the creatine
content of several foods. The Mayo Clinic states that creatine has
been associated with asthmatic symptoms and warns against consumption
by persons with known allergies.
While there was once some concern that creatine supplementation could
affect hydration status and heat tolerance and lead to muscle cramping
and diarrhea, recent studies have shown these concerns to be unfounded.
There are reports of kidney damage with creatine use, such as interstitial
nephritis; patients with kidney disease should avoid use of this
supplement. In similar manner, liver function may be altered,
and caution is advised in those with underlying liver disease although
studies have shown little or no adverse impact on kidney or liver function
from oral creatine supplementation.
Long-term administration of large quantities of creatine is reported
to increase the production of formaldehyde, which has the potential to
cause serious unwanted side-effects. However, this risk is largely
theoretical because urinary excretion of formaldehyde, even under
heavy creatine supplementation, does not exceed normal limits.
Extensive research over the last decade has shown that oral creatine
supplementation at a rate of 5 to 20 grams per day appears to be very
safe and largely devoid of adverse side-effects, while at the same
time effectively improving the physiological response to resistance
exercise, increasing the maximal force production of muscles in both
men and women.
Creatine use is not considered doping and is not banned by the majority
of sport-governing bodies. However, in the United States, the NCAA recently
ruled that colleges could not provide creatine supplements to their players,
though the players are still allowed to obtain and use creatine
testosterone (with red double bond), dihydrotestosterone (without double bond)
Creatine increases the conversion rate from testosterone to
dihydrotestosterone (DHT) in the body.
In men, approximately 5% of testosterone usually undergoes 5α-reduction
to form the more potent androgen, dihydrotestosterone. DHT has approximately
three times greater affinity for androgen receptors than testosterone
and has 15-30 times greater affinity than adrenal androgens.
A 2009 study showed that after a 7 day
loading phase of creatine supplementation, followed by a further 14 days
of creatine maintenance supplementation, while testosterone levels in
blood serum were unchanged, levels of dihydrotestosterone increased by
56% after the initial 7 days of creatine loading and remained 40% above
baseline after 14 days maintenance. The ratio of dihydrotestosterone to
testosterone also increased by 36% after 7 days creatine supplementation
and remained elevated by 22% after the maintenance dose. This could
explain the fact that creatine users tend to report a slight onset of
acne after starting creatine supplementation. It could also be a factor
when it comes to the increased athletic performance that has been correlated
with creatine supplemenation.
Chromium(III) picolinate is marketed as a nutritional supplement to prevent
or treat chromium deficiency. The bright-red coordination complex is derived
from chromium(III) and picolinic acid. Small quantities of chromium are
needed for glucose utilization by insulin in normal health, but deficiency
is extremely rare and has only been observed in hospital patients on
long-term defined diets.
Some commercial organizations promote chromium picolinate as an aid
to body development for athletes and as a means of losing weight.
Note however that a number of studies have
failed to demonstrate an effect of
chromium picolinate on either muscle growth or fat loss.
Design and Materials in Athletics. Nick Linthorne shows the changes
technology has made in a number of athletic events and plots the average result
for the 10th best athlete in the world for these events.
Much of the information in these course notes has been sourced
from Wikipedia under the Creative Commons License. Students
taking this course will be expected to contribute to Wikipedia as
a part of their course assignments.
Continue to Equipment or return to CHEM2402 course outline.
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last modified 17th October 2014.