Polyphenol Supplements and Other Strategies
for Athletes at the ACSM Annual Meeting Will G Sportscience
12, 1-7, 2008 (sportsci.org/2008/wghACSM.htm)
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This
year’s annual meeting of the American College of Sports Medicine was held in
Indianapolis, May 28-31. Indy is not
the most interesting of cities, so I will move straight on to the conference
itself, which consisted of over 2500 presentations on the relationships of
physical activity with health, injury and performance. As usual, I have
limited this report mainly to the studies of factors affecting athletic
performance. If you have other interests in physical activity and you want to
access the most up-to-date research, you should download and search the
abstracts–I explain how below. And you should come to next year’s meeting, in
Seattle. A
criticism I level at ACSM every year is the lack of abstracts for all the
special sessions. If you can’t get to one of these sessions because of a
clash, you miss out on all the wisdom of the experts in that session. Other conferences often provide a full
transcript of the keynote addresses.
The least ACSM could do is provide an abstract. Next, my
usual pleas to the authors of the abstracts…
Show the magnitude of an effect and its uncertainty (confidence
interval or limits), not a P-value and especially not a P-value inequality.
Base your conclusion on the uncertainty in the magnitude, not on statistical
significance or non-significance. In a
controlled trial, don’t compare the significance of the experimental and
control groups: P=0.06 vs P=0.04 doesn’t mean you have an effect! Finally,
use as few abbreviations as possible: they make some abstracts unreadable. As with
last year’s meeting, it’s possible to access the abstracts on line. You have
to be a member of ACSM, or you or your institution must have a subscription
to ACSM's journal, Medicine and Science
in Sports and Exercise. ACSM
members, log in via this link.
Enter your username (default is first 3 letters of your family name
followed by your member number) and password (your member number). Click on the MEMBER SERVICES tab, then on
the link for Member Journals, then the link for MSSE. Otherwise get to this point at the MSSE site via your institution and/or log in with your own
subscription info. Now, click on the main Search tab (not the one in the
Quick Search box). In the Title field
of the search form, type the presentation number shown [in brackets] in this
article, select 2008 to 2008 for the date range, then click SEARCH. You
should get one hit, the abstract you want.
Some of the hits have a link to a large PDF containing the abstract. There are five PDFs, one each for the
featured sessions, slides, clinical case slides, thematic posters, and
posters. Strangely, only the first few
presentations in each PDF show a link to the PDF. So, if you want the complete PDF for each
type of session, put the following word in the Title field of the search form:
neuropsychological (for featured sessions–too hard to explain why
“neuropsychological” works), 513 (for slides), 1042 (for clinical cases),
1215 (for thematic posters), and 1262 (for posters). If all else fails, email me. Science and Performance Enhancement
One of
the few symposia I couldn’t miss was titled The Role of Sports Science in Improving Athletic Performance. David Bishop outlined his model of the
sport-science process that he published recently (Bishop, 2008).
I don’t agree with the sequence of stages in his model: defining the
problem, descriptive research, prediction of performance, experimental
testing, determinants of key performance predictors, intervention (efficacy)
studies with ideal-conditions evaluation, barriers to uptake, and
implementation in a sport setting. This sequence is neither real nor ideal, in
my opinion. All these stages can be
aspects of performance-based research, but the reality is more chaotic and interesting. The next two speakers, Alejandro Lucia and
Jos de Koning, stayed in their own research and did not present anything
inspirational. Randy Wilber then made up for all with an outstanding account
of how he has helped USA Triathlon prepare for the Beijing environment, the
main considerations being air pollution, acclimatization and facilities.
These guys deserve to win. The final
speaker was Olympian Sheila Taormina, who gave a lively account of the ways
in which sport science has contributed to her success. Surprisingly, none of the speakers touched
on the issue of delaying publication of the most valuable discoveries. Acute Effects
A couple
of posters showed post-activation potentiation
for an explosive movement at 4 and
5 min after the conditioning exercise [1623, 1633], and another showing enhancement
of shot-putting that seemed clear
enough (max of five shots, 3.2%) in
the sample of only 4 athletes [2508].
Use it! It was
news to me, but in a recently published study acute administration of the
dopamine/noradrenaline reuptake inhibitor bupropion
produced a 9% enhancement of power output in a pre-loaded cycling time trial in the heat, possibly by allowing the cyclists to
tolerate a slightly higher core temperature (Watson et al., 2005).
The effect on performance was magnified by the preload, so in a
straight time trial it would be more like 3-4%. Effects on performance reported here with chronic administration were negligible
[1922], presumably because of desensitization. The author shared his belief with me that,
at their peril, competitive cyclists are already using this stuff, which is
not yet banned by the IOC. Computational fluid dynamics indicated that it might be better
for swimmers to abduct the thumb
[725] in freestyle. Watch for more findings with CFD, as computing power
increases. Adding a dolphin kick
during the breaststroke pullout (of
the turn) seems to work [2098]. By
estimating the time course of anaerobic and aerobic contributions in four
1500-m time trials with 7 cyclists,
the authors concluded that the most successful pacing
strategy was a short fast start
[1302]. This sort of study needs a
bigger sample size. Manipulation
of the cadence during the cycle
phase of a triathlon had effects on
oxygen cost in the subsequent run phase, but I sailed past the poster, the
abstract lacks data, and the effects on overall performance weren’t clear
[1279]. Use of a cooling vest
during a warm-up had a negligible effect on performance of a 10-km time trial
at 24-26ºC in a crossover with 7 male runners
[2059]. On the other hand, cooling the
neck throughout exercise works [2060], but I can’t see how you could use this
strategy in a race. Whole-body
vibration didn’t seem to have much
acute effect on strength [1610],
and there were mixed findings in a thematic poster session devoted to the
topic [1228-1233]. Various
kinds of stretching had little
effect on bench-press 1RM [1622],
but static stretching impaired running
performance [699] and rhythmic gymnastics
performance [2115]. Ozone
alone (data not shown) “does not impair” distance-running
performance, but it does when combined with heat and humidity [2040]. Biostatistics
Steve Marshall and I presented a conversational forum on sample size (chaired by Ian Shrier) and a colloquium on statistical guidelines for reporting research. Both talks had been organized by Allan Batterham, who was unable to attend, because the birth of his daughter coincided with the conference. The slides for our sample-size talk can be downloaded via the article on sample size at this site (Hopkins, 2006). See an In-brief item in this issue for a link to the slides we used for the stats guidelines. To our great relief, the audience reacted positively to the innovative and controversial issues in both talks. Nutrition Preconference
A
conference on sports nutrition was organized by Asker Jeukendrup for the day
before the start of the ACSM meeting.
Six speakers each specializing in a different kind of sport presented
tutorial lectures to an audience of ~90.
Here are the main points. Middle-distance running and other endurance events lasting 2-10 min was Trent Stellingwerff’s
specialty. Nutrition should be
periodized alongside the training program: from the general prep phase
through the competition phase, carbohydrate (CHO) increases from 60% through
70% of energy while fat falls from 28% through 18%; protein stays constant at
12%. To optimize short-term (<4 h)
recovery of muscle glycogen for another training bout or competition on the
same day, consume CHO every 20-30 min at the rate of 1.2-1.5 g/kg/h. Adding protein won’t increase the rate of
resynthesis, but protein is important for longer (24 h) recovery periods to
get the anabolic training response to the catabolic training stimulus. The best blend of CHO and protein and the
best timing are unclear. He
recommended use of bicarbonate and beta-alanine supplements to increase
buffering of acid. Bicarbonate works
acutely in male athletes, but not in females, in his experience, although
it’s hard to imagine why not. It also gives 50% of athletes serious gut
problems for several hours, so it’s no good for a final following soon after
a semi-final. Beta-alanine works by increasing the amount of carnosine, an
intracellular buffer in muscle; it needs to be taken 5-6 times a day, at a
rate of 3 g/d, for at least several weeks.
Trent finished by observing that more research is needed on the
question of training in a glycogen-depleted state. In response to a question
about control of weight, he said that it is better to be ~3% above race
weight during non-competitive phases, and to increase protein intake during
weight reduction so you don’t lose muscle mass (if that is an issue). Athletes should be in the “red zone” of low
body mass only for 3-4 wk per year.
Body fat in the red zone is 10-14% of body mass, depending on the
athlete. Asker
Jeukendrup focused on competing in the Ironman
triathlon. His research shows that CHO mixtures
(fructose and sucrose or maltodextrin) can be absorbed at the rate of 90+
g/h. Athletes don’t normally consume such quantities, so to sustain the high
intake it is important to avoid “taste fatigue”. Gels are well tolerated [see Abstract 672],
as are high-CHO low-fat low-fiber foods (e.g., bananas, bread rolls and
jam). A single drink bottle containing
concentrated CHO solution augmented with water at drink stations is another
strategy. It is also important to
realize that “the gut is trainable”, so the athlete should get used to
high-CHO intake in training sessions. John
Hawley deviated from his talk on the marathon
to present results of his own recent research. He has found that athletes adapt to
steady-state training sessions on low glycogen after several weeks, with
little effect on performance (although he did not present performance data,
and did that include sprint performance?).
He has also found that caffeine increases the rate of glycogen
resynthesis by about 50% in the first 4 h following exercise [see 669], but
the dose was so high (8 mg/kg) that it could harm performance if you took it
between games or heats and finals. A
smaller does would probably still work on restoring glycogen and would also
enhance performance directly in the following game or event. In a
panel discussion with the first three speakers, champion Ironman Tim DeBoom shared some of his
secrets. He does “train-low” sessions
(i.e., trains on low glycogen) only early in the season. His competition breakfast
is French toast with syrup. He cuts
out caffeine for a week before a race, has coffee on the morning of the race,
but holds off on caffeine until into the run. And he eats a Power Bar as soon
as he starts the cycling phase. Adventure racing was presented by Mark Tarnopolski, himself an experienced champion in
this sport. Race intensity soon levels
off at 35-45% of VO2max, but the race starts at high intensity, so CHO loading is
important. Nutritional requirements
are CHO ~1 g/kg/h and protein ~1.6 g/kg/24h.
Extra salt intake is important, especially in hot conditions. Caffeine
enhances performance and helps keep you awake. Reduce nausea and cramps with
Tums or Rolaids. In tropical venues
purify water with Pepto-Bismol. In his
talk on team sports, Stu Phillips
noted that repeated sprinting has the same nutritional needs as longer
endurance events, so hydration is as important as CHO during and after the
game, and protein is also important for recovery after the game. The jury is
still out on the issue of the glycemic index of the CHO. Louise
Burke began her talk on swimming by
noting that there is a trend towards a positive relationship between leanness
and performance, so there is a need to balance changes in energy input with
output when changes occur in adolescence, tapering, racing, injury, recovery,
institutional and social settings. She wondered whether LZR racing suits
would have a bigger effect on swimmers with more fat by reducing drag that
might arise from rippling of the skin. For key workouts she recommended CHO
and protein before, CHO and fluid during, and CHO and protein after. Adequate
CHO, especially for hard training, is the most important issue. The CHO demand of swim training is 30-60
g/h, which can be provided by sports drinks consumed at the rate of 0.5-1
L/h. Variety through use of gels and
bars is also important. On the issue
of supplements… Bicarbonate works, but can have side effects. Creatine can benefit interval training, but
whether that translates into gains in competitive performance is
unclear. Caffeine is also effective,
but is problematic in a situation where it can disrupt sleep before a
competition. Monitoring over a period
of years allows for useful individualization of dietary strategies. Louise then led a panel discussion, in
which it was noted that, on the evidence to date, milk has the best blend of
amino acids. Ron
Maughan was at the conference and shared an interesting idea over lunch. Athletes who want to build muscle mass now
routinely use high-protein diets. They
believe in them, because whenever they come off the high protein, they lose
muscle mass. But they lose muscle mass, because the high-protein diet
up-regulates protein catabolism, so when they reduce protein intake, their
muscles break down until the protein catabolism down-regulates to a level appropriate
for the lower protein intake. Chances are they could have built up the muscle
mass without the massive intake of protein, which increases the risk of
osteoporosis and possibly other health problems long term. Nutrition
The title
of the abstract says it all: polyphenol
supplementation attenuates strength
loss 2-3 days following eccentric damage
[1561]. Yes, it’s that usual muscle-damage
model with untrained subjects, and yes, muscle damage is a necessary part of
the anabolic adaptation process, but it’s possible these extracts of fruit or
berries (here, pomegranates) might allow you to train harder and/or recover
quicker. We need some long-term studies. Black-tea extract looks even more promising, if reducing muscle soreness, oxidative
stress and cortisol following high-intensity interval
training is a good thing [1562]. An antioxidant supplement made by Watkins might
have had some benefit on muscle soreness and a marker of muscle damage when consumed for 3 d each side of a
bout of eccentric exercise, but it’s hard to say from the way the data were reported
[1563]. A resveratrol supplement (equivalent to about
100 glasses of red wine) taken by 14 trained runners
for 1 wk before a 1-h bout of hard running reduced markers of oxidative
stress and inflammation in comparison with placebo, but another polyphenolic
supplement, catechin (a component
of green tea), had little effect in the crossover [1570]. Actually, the effect of both supplements on
protein carbonyls looks worrying, even if “no treatment effects existed”. Acute
supplementation with the “non-specific antioxidant” N-acetylcysteine reduced respiratory fatigue
but if anything reduced time to
fatigue (by 17%, equivalent to a ~1% impairment in a time trial) in 8
sedentary men [1803, 1804]. There was
a clearer outcome of the effect of 5 d of unspecified antioxidant supplementation on time-trial
performance (following a pre-load) of 8 trained cyclists
in (apparently) a crossover: 1.0% more power in the placebo condition [1568].
It looks like some antioxidants will be harmful for athletes. But caffeine still works acutely: @ 3 mg/kg it enhanced VO2max and lactate
threshold in cross-country runners
[2030]; @ 6 mg/kg it improved skill in simulated soccer
activity [2031]; @ 5 mg/kg it increased peak power in cyclists [2032]; @ ~1mg/kg (as chewing
gum) it surprisingly increased shot-put distance [2036]; and @ ~1.4 mg/kg
it produced large improvements in cognitive performance of cyclists during steady exercise and enhanced
subsequent time to exhaustion [2041].
There were no studies of the chronic effects of caffeine used in
training. The
authors claimed their lack of a significant effect in a crossover with 8
runners did not support the use of bicarbonate
to enhance middle-distance running
speed, but the observed effect was 1.3% [1252]. Thanks, I’ll take it, provided I can get
used to the side effects. Several
studies in a slide session on acute effects of energy
supplements were too badly reported
in the abstract (no data, “no difference”) or had too few subjects to be
worth summarizing [849, 850, 854]. Not
surprisingly, glucose+fructose in a
supplement resulted in better 100-km cycling
performance compared with isocaloric glucose [851]. A high-fat diet for 2 d before a duathlon impaired run+cycle time by 1.1%
(“not altered”!) in a crossover with 11 athletes, but it’s unclear whether
they supplemented during the test [852].
Swimmers
felt more energetic when they consumed carbohydrate
before their morning training sessions [853]. The data
aren’t reported properly, so it’s hard to tell exactly how much better triathletes did in ”treadmill exhaustive
exercise” when they consumed hydrolyzed whey
protein enriched with glutamine dipeptide [960]. In a
featured session on carbohydrate-protein
interactions, the big message from keynote speaker Martin Gibala was that
adding protein to an acute supplement doesn’t enhance endurance performance if you have enough
carbohydrate there already [no abstract].
In the first original-study presentation in the session, we learned
that a small amount of protein can replace a lot of carbohydrate (0.75%
protein plus 3% CHO vs 6% CHO) for endurance performance lasting ~3 h in
total [350]–interesting but irrelevant, given that Asker Jeukendrup’s CHO
mixtures for such exercise amount to drinks containing ~10% CHO or more. The
next speaker then presented data showing that, if anything, addition of
protein to a supplement produced more
damage following 90 min of shuttle running [351]. However, the last keynote speaker Luc van
Loon assured us that you need protein post-exercise to get nett positive
protein balance [no abstract]. In
question time, muscle damage was described as a necessary evil in training,
but of course you avoid it prior to competing. A protease supplement taken by 4 males and 4
females 4 times a day for 4 d before a muscle-damaging
bout of eccentric exercise more than offset the decline in strength that
occurred in a matched group in the following 3 d (nett difference, 15%)
[1368]. The supplement apparently reduces inflammation. Two weeks
of supplementation with beta-glucan
(a polysaccharide derived from oat bran) had little effect on immune function
and upper respiratory infections in a placebo-controlled trial with 36
trained cyclists [577]. Acute arginine supplementation resulted in fewer chin-ups
[2200] and had little apparent effect on endurance-related
physiology of tennis players
[2199]. Chronic coenzyme Q10
supplementation might enhance endurance
[2203]. Cystine
and theanine supplementation
appears to have a protective effect on the suppression of immune function
that occurs with hard training [2204]. Studies
of creatine suffered either from
lack of a control group [939] (although the effect of training with creatine
combined with protein appears to have been massive), unclear reporting [941,
942], or inadequate sample size [942]. Beta-alanine
consumed daily for 4 wk produced a 22% increase in the number of reps during
training in a crossover study of 8 resistance-trained men [1253]. This stuff
is clearly anabolic, but it’s a pain to take the multiple daily doses for
weeks on end. In case you had any doubts,
appropriate hydration does actually
benefit performance [832-837].
Interestingly, protein in a
sports drink enhanced fluid retention and performance in an 8-d cycle stage race in the heat [835]. In a
study of hydration, 9 female soccer players sprinted 1.8% faster when
they consumed 3 ml/kg of water every 15 min compared with consuming no water
in a 90-min performance test in a 17ºC environment. There were “no significant effects” on
passing skill (but no data shown thereof) [1348]. In a
meta-analysis with everything done right (OK, I did help the authors informally),
dehydration of >1.7% body mass
starts to impair endurance performance,
and the effect on power output is then 3.0% for each 1% loss of body mass
[2177]. What is
the effect of carbohydrate content
of a drink on rehydration following
exercise in the heat? The drinks were
water, 18 mM Na+, and 18 mM Na+ with 3, 6 and 12% carbohydrate (of
unspecified type). In the hour following
exercise the subjects (men) consumed a volume of drink equal to the 2.6% loss
of body mass. By 4 h post exercise the
percent of drink retained was 66, 72, 75, 75 and 82 respectively [888]. The
conclusion that electrolytes are the primary driver for fluid retention is
obviously wrong. In a similar study, rehydration with a non-caloric
electrolyte drink was allegedly “no different” from that with Gatorade [889],
but the key data aren’t shown. Come on, carbohydrate improves rehydration. Tests
and Technology
Using all
the bells and whistles on a cycling
computer for 8 wk led to greater improvements
in lactate threshold in a group of 14 cyclists compared with a matched group
who used the basic version, presumably by increasing the quality of training,
although that’s not apparent in the data as presented [1291]. Or is it an artefact of the misleading way
the results are presented: significant in the study group, not significant in
the control, but maybe no substantial difference between the two groups? The
correlations are probably artifactually high (0.97), because the errors of
measurement of 16% for training distance and 11% for training speed are
probably too large for a “commercial accelerometer”
(which one of the many?) to be useful to monitor swim
training [2121]. VO2max
gets bad press as a predictor of performance of top endurance athletes, but
it was quite good at tracking changes in peak running speed during a winter
season in 34 competitive runners;
however, there was little extra value in measuring changes in running
economy, lactate threshold or body mass [2277]. These researchers are amongst the best at
doing VO2s and lactates, so I conclude that there is no point in tracking
physiological indices of endurance performance. Training
The researchers called it intermittent
hypoxia, but it was more like
live-low train-high; anyway, after 6-7 days of 3 h per day, if anything the
11 men performed much worse than the placebo group of 7 in a time trial at
4300 m [1263]. So, no evidence here
for any benefit of artificial hypoxia for pre-acclimatization
to altitude, but in another study there was a benefit for acute mountain sickness
and cognitive performance at altitude [1269, 1270]. Although
there were only 5 experimental and 4 control highly trained cyclists, 3 wk of altitude training
at 2700 m produced a likely reduction
in exercise economy [1265], the opposite of what the artificial-altitude
fraternity (myself included) would like to see. You might
not have to go that high to get extra blood from altitude
training: two 3-wk camps at 1300 m and 1650 m
separated by nearly 3 wk produced a 5.1% increase in hemoglobin mass
and increases in markers of erythropoiesis in 8 middle-distance runners
[1266]–which sounds great when the control group was “unchanged”, but
actually the control group increased by 3.6% (the authors somehow failed to
calculate it). OK, there is probably a
benefit from the low-ish altitude here, but higher is better. Don’t
bother measuring ventilatory sensitivity to hypoxia if you want to identity
individual responders to altitude training
[1267]. Adaptation
to the brief intermittent version of hypoxia (simulated altitude) for 15 d
appeared to produce a ~4% increase in time-trial power output in 9 male
cyclists, but the data for what appears to have been a placebo group are in
the abstract only as “no [significant] improvement” [733]. Sigh… Most of
the increase in hemoglobin mass in 8 elite cyclists
occurred during the first 11 d of a 4-wk altitude-training
camp at 2760 m [738]. Wow, so you need
only 2 wk up a mountain? And does this
mean the gains will disappear just as quickly? Probably–red cells are more labile than
people realize. Ten weeks
of interval training in combination with body-mass
reduction did not give any extra increase in power/weight ratio compared with
interval training or body-mass reduction alone in experienced cyclists [1290], but the sample sizes were a
bit small (7-11 per group). Also, the
gains were so large (8-10%) that it must have been in the base phase, so the
relevance to the competitive season is unclear. Ten triathletes doing 10 wk of cycle training
with “independent cycle cranks” (presumably PowerCranks)
for 3 h per week along with usual training performed no better in a (20-km?)
cycling time trial and considerably worse (3.6%) in a 5-km running time trial
compared with a matched group who did usual cycle training. Another matched
group who did 1.5 h per week with the cranks performed a lot better in the cycle (5.1%) and a bit better in the run
(1.3%) than the control group, although there were “no significant
differences” [1293, 1294]. So, some
use of PowerCranks could be worthwhile?
Depends… my cycling-guru colleague Carl Paton, who has trained with
PowerCranks, believes that any gain comes from the high-resistance intervals
you end up doing through having to use a lower gear (and such training
produces big gains with endurance cyclists).
And if you use them too much, you wreck your legs. There are better
ways to do high-resistance training. Core stability training twice a week for 7 wk using a unique arrangement of slings resulted
in a nett 6.2% improvement in throwing
speed in a controlled trial of 23
female handball players [620]. And
trunk instability was a risk factor
for injury in baseball pitchers
[726]. The data
for the sham group weren’t presented, but it looks like inspiratory muscle
training enhances time to exhaustion
by 16% (equivalent to ~1% in a time trial) in asthmatics
[1806]. There was a similar nett
effect (1.2% in a time trial) in 14 college-level cross-country runners randomized to effective vs ineffective
inspiratory muscle training [1807].
These gains aren’t that great, especially if, as seems likely, the
study wasn’t done in the competitive season. No data
were given, but cold-water immersion
and contrast (alternating hot- and
cold-water immersion) forms of hydrotherapy
produced higher power output over 5 consecutive days of hard training
compared with hot-water immersion and passive recovery in a crossover study
of 12 endurance cyclists [803]. In a case
study of a triathlete, a
Banister-style fitness-fatigue model of effects of training on performance
predicted that the best taper would
be different for the swim, cycle and run phases [1288]. Swimming, cycling and running performances were tested ~twice a week, but
the tests each lasted only a couple of minutes, so one should be cautious
about the relevance to competitive triathlons. The
sample size was pitiful (6 experimental, 4 control), so the claim that a
sport-specific vision-training
program enhanced ability of softball
players to catch with the non-dominant hand should be treated as a likely
Type I error, considering there were at least 5 performance tests, and maybe
10 if each was done on dominant and non-dominant hands [2114]. Elite
Kenyan marathon runners excel by
having a fractional utilization and economy that outweigh their relatively poor
VO2max [805]. Hard training and
spindly legs! Travel for my attendance at ACSM was funded mainly by NordForsk (as part of a statistics workshop I ran at the Institute of Sports Medicine in Copenhagen prior to ACSM), with additional funding from Sport and Recreation NZ and the School of Sport and Recreation of AUT University. My thanks to all the people involved. References
Bishop D (2008). An applied research model for the sport sciences.
Sports Medicine 38, 253-263 Watson P,
Hasegawa H, Roelands B, Piacentini MF, Looverie R, Meeusen R (2005). Acute
dopamine/noradrenaline reuptake inhibition enhances human exercise performance
in warm, but not temperate conditions. Journal of Physiology 565, 873-883 Hopkins
WG (2006). Estimating sample size for magnitude-based inferences.
Sportscience 10, 63-70 Published June 2008. |