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882 Nutrition
Earnest CP et al. Astaxanthin Time Trial Performance … Int J Sports Med 2011; 32: 882–888
accepted after revision
May 16 , 2011
Bibliography
DOI http://dx.doi.org/
10.1055/s-0031-1280779
Published online:
October 7, 2011
Int J Sports Med 2011; 32:
882–888 © Georg Thieme
Verlag KG Stuttgart · New York
ISSN 0172-4622
Correspondence
Dr. Conrad. P. Earnest, PhD
Pennington Biomedical
Research Center
Exercise Biology Laboratory
Perkins Road
70808 Baton Rouge
United States 6400
Tel.: +1/225/763 2632
Fax: +1/225/763 2632
Conrad.Earnest@pbrc.edu
Key words
●
▶
cycling
●
▶
nutrition
●
▶
ergogenic aid
●
▶
performance
●
▶
supplement
Eff ect of Astaxanthin on Cycling Time Trial
Performance
However, if enhanced lipid metabolism is a pro-
posed benefi t of AST supplementation, it seems
more intuitive to examine exercise bouts of
longer duration. Accordingly we are unaware of
any published studies examining the eff ect of
AST supplementation for prolonged periods of
exercise endurance performance in humans. The
primary aim of our current study was to examine
whether 28 days of AST supplementation would
improve exercise following a 2 h pre-exhaustion
ride designed to minimize carbohydrate contri-
bution during exercise performance. Our second-
ary aim was to determine whether 28 days of AST
supplementation modulates indices of carbohy-
drate and lipid metabolism.
Material and Methods
▼
Participants
We recruited amateur endurance-trained males
from 18 to 39 years of age who had a VO2 max
≥ 50 ml/kg/min, were actively participating in
competitive cycling activities such as competi-
tive road cycling or triathlons, and were accumu-
Introduction
▼
Astaxanthin (AST) is a carotenoid belonging to a
larger class of phytochemicals known as terpenes
that can be found in microalgae, yeast, salmon,
trout, krill, shrimp, crayfi sh, crustaceans, and the
feathers of some birds [ 5 , 7 , 9 , 10 , 16 ] . Currently,
the FDA permits the use of AST as a food coloring,
as well as an additive for animal and fi sh foods.
Perhaps AST’s most notable use is as a feed addi-
tive for farm raised salmon, giving the salmon its
reddish tissue color. While AST is a natural nutri-
tional component found in food it can also be
purchased over-the-counter as a dietary supple-
ment. Astaxanthin has recently received atten-
tion due to its ability to scavenge free radicals,
decrease infl ammation, improve indices of lipid
metabolism and attenuate lipid accretion, and
increase exercise time to exhaustion in mice
[ 1 , 2 , 7 , 12 , 15 ] .
To date, only one study has examined the effi cacy
of AST supplementation on endurance exercise
performance in humans, whereby 4 weeks of AST
supplementation was shown to reduced lactic
acid build up following 1 200 m of running [ 14 ] .
Authors C. P. Earnest
1 , M. Lupo
1 , K. M. White
2 , T. S. Church
3
Affi liations
1 Pennington Biomedical Research Center , Exercise Biology Laboratory , Baton Rouge , United States
2 Gatorade, Sports Science Institute , Barrington , United States
3 Pennington Biomedical Research Center , Preventive Medicine , Baton Rouge , United States
Abstract
▼
We examined the eff ect of Astaxanthin (AST) on
substrate metabolism and cycling time trial (TT)
performance by randomly assigning 21 competi-
tive cyclists to 28d of encapsulated AST (4 mg/d)
or placebo (PLA) supplementation. Testing
included a VO
2max test and on a separate day a
2 h constant intensity pre-exhaustion ride, after
a 10 h fast, at 5 % below VO
2max stimulated onset
of 4 mmol/L lactic acid followed 5 min later by a
20 km TT. Analysis included ANOVA and post-
hoc testing. Data are Mean (SD) and (95 % CI)
when expressed as change (pre vs. post). Four-
teen participants successfully completed the
trial. Overall, we observed signifi cant improve-
ments in 20 km TT performance in the AST group
(n = 7; − 121 s; 95 %CI, − 185, − 53), but not the
PLA (n = 7; − 19 s; 95 %CI, − 84, 45). The AST group
was signifi cantly diff erent vs. PLA (P < 0.05). The
AST group signifi cantly increased power output
(20 W; 95 %CI, 1, 38), while the PLA group did
not (1.6 W; 95 %CI, − 17, 20). The mechanism of
action for these improvements remains unclear,
as we observed no treatment eff ects for carbohy-
drate and fat oxidation, or blood indices indica-
tive of fuel mobilization. While AST signifi cantly
improved TT performance the mechanism of
action explaining this eff ect remains obscure.
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883
Earnest CP et al. Astaxanthin Time Trial Performance … Int J Sports Med 2011; 32: 882–888
Nutrition
lating a weekly cycling volume of 160 km per week. Initially, we
considered using a mixed cohort of men and women, however,
decided against it for 2 primary reasons. First, it has been pur-
ported that carbohydrate and fat metabolism diff er between
genders with respect to prolonged exercise [ 18 ] . Thus, a mixed
cohort would add variance to our study that we would not be
able to account for using a relatively small sample size. Second,
we, and others in our community (Baton Rouge, LA, USA), have
found it diffi cult to recruit women for more strenuous exercise
protocols such as the one undertaken for this study. Hence, we
focused our current recruitment eff orts on men, whose cardio-
respiratory fi tness measures are presented in
●
▶
Table 1 . The
ethical review committee at Pennington Biomedical Research
Center approved our study and informed consent was obtained
from all participants before entering the trial. All study proce-
dures conformed to the Declaration of Helsinki and ethical
standards of IJSM [ 8 ] . We have provided a CONSORT schematic
outlining the overall study timeline in
●
▶
Fig. 1 .
Recruitment and baseline testing
We initiated our recruitment eff orts by contacting local cycling
clubs via email, who therein posted our study details on various
online forums and discussion boards. Upon expressing interest
in the study, we contacted potential candidates via phone and
email. Following a successful screening procedure we invited
study candidates to come to the Pennington Biomedical Research
Center Exercise Biology Laboratory Testing Core where they
were further screened to participate in our study protocol. The
entire length of the study for each participant ranged from 35 to
40 days. Briefl y, participants attended a baseline run-in period,
inclusive of exercise testing to determine maximal cardio-
respiratory capacity (details below), 20 km TT rehearsals, and a
fasted 2 h pre-exhaustion ride that was followed immediately by
a 20 km TT (details below) on their own bike using a Compu-
trainer ergometer (Seattle, WA). Before each Computrainer test
the ergometer was turned on and allowed to warm-up for
30 min. Immediately before each TT we also performed an indi-
vidualized calibration procedure that accounts for rolling resis-
tance. We have presented a schematic of all testing procedures
in
●
▶
Fig. 2a .
Maximal cardiorespiratory exercise
We instructed each subject to prepare for his VO
2max test as if
preparing for a race and to abstain from exercise for 24 h before
the test. This preparation included not changing their training
parameters or dietary patterns for the week preceding each test.
We asked participants to record what they ate in a food log 3
days before testing and to duplicate the same food intake on the
penultimate day before testing during the follow-up visit. Par-
ticipants were also instructed to eat a light snack ~3 h before
their tests and to abstain from ingesting any medications that
would infl uence heart rate on the day of each test. The one
exception was caff eine, which we asked participants not to con-
sume for at least 5 h before testing.
We performed all VO
2max exercise tests on a Lode Excalibur Sport
Ergometer (Groningen, The Netherlands) and analyzed the riders
for various cardiorespiratory parameters using a Parvomedics
TrueMax Metabolic System (Salt Lake City, UT). Each cycling test
began with a warm-up at 50 W (10 min) and then progressed to
75 W (2 min). After the warm-up, the test began by increasing the
power output (PO) to 100 W. Once PO was set at 100 W, each stage
inclusive of the 100-W stage lasted 3 min and progressed 35 W
every 3 min until the rider reached exhaustion or could no longer
maintain a pedal cadence of 50 rpm. We allowed each rider to
choose their preferred cadence within a range of 70–90 rpm.
We collected gas exchange data continuously using an automated
computerized breath-by-breath Parvomedics TrueMax Metabolic
System. The TrueMax system uses a pneumotachometer, a para-
magnetic O
2 analyzer, and an infrared CO
2 analyzer to analyze
respiratory O
2 and CO
2 , respectively. Before each test, we followed
a standard calibration procedure for each metabolic cart including
a fl ow calibration using a 3-L calibration syringe and calibration
against standardized gases (16 % O
2 , 4 % CO
2 , and balanced nitro-
gen) obtained from the manufacturer of the metabolic system.
We averaged all gas exchange data in 60 s intervals and only the
last minute of each stage was used in our analyses. Blood samples
(25 uL) for the measurement of blood lactate (Lactate Pro, Ques-
nel, BC, Canada) were taken from the riders fi ngertips at rest and
during the last 30 s of each stage starting at 75 W. From these lac-
Fig. 1 CONSORT diagram of study enrollment.
Email Response
(N=79)
Eligible for Baseline
(N=26)
Exclusion
N=53, Failed to meet
inclusion criteria
Exclusion
N=3, Insufficient VO2max
N=2 Failure to complete
2 hr ride
Successfully Completed
Baseline (N=21)
Randomized to
Treatment (N=21)
Treatment
(N=11)
Completed
(N=7)
Completed
(N=7)
Placebo
(N=10)
Withdrawn
N=1, Illness
N=1, Computer
Failure
N=1, Unable to
Complete Protocol
N=1, Invalid
pretest
Withdrawn
N=2, Unable to
Complete Protocol
N=1, Invalid
pretest
All (N=14) Astaxanthin (n=7) Placebo (n=7)
V O 2max (L/min) 3.88 (0.4) 3.98 (0.3) 3.79 (0.4)
V O 2max (ml/kg/min) 52.84 (3.5) 54.14 (4.1) 51.53 (2.4)
Maximal PO (W) 330 (26) 335 (17) 325 (34)
HR max (b/min) 185 (9) 183 (11) 187 (7)
PO (W) @ 2 mmol/L BLa 141 (57) 144 (62) 138 (57)
percent of VO 2max @ 2 mmol/L BLa 50.90 (12.9) 49.08 (14.7) 52.45 (12.0)
PO (W) @ 4 mmol/L BLA 228 (47) 227 (43) 229 (55)
percent of VO 2max @ 4 mmol/L BLa 73.65 (9.7) 71.66 (8.9) 75.63 (10.0)
Data are mean and SD
Table 1 Baseline fi tness charac-
teristics of study participants.
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884
Earnest CP et al. Astaxanthin Time Trial Performance … Int J Sports Med 2011; 32: 882–888
Nutrition
tate measurements we determined the corresponding PO associ-
ated with the accumulation of 2 mmol/L and 4 mmol/L of lactic
acid accumulation by drawing a 3
rd order line of best fi t through
all data points. For the 2 h ride we asked riders to work at a PO
corresponding to 5 % lower than the PO associated with the accu-
mulation of 4 mmol/L of lactic acid.
Two-hour and 20 km TT performance testing
We have presented a schematic outlining the procedures for the
2 h pre-exhaustion and TT ride performed at baseline and fol-
low-up in
●
▶
Fig. 2b . For the 2 h pre-exhaustion fasting ride, we
asked participants to report to the Pennington Exercise Testing
Core on the morning of their test where we placed an indwelling
catheter into an antecubital vein 30 min before their ride. We
also determined participant hydration status designated as hav-
ing a urine specifi c gravity (USG) less than 1.025. During the TT
we instructed participants to ride the 20 km distance as fast as
possible on his own bicycle. To ensure minimal variability
between tests we asked the participants ride the same bike with
the same confi guration for positioning during the rehearsal,
baseline and follow-up testing conditions. Approximately 20 min
after the insertion of the catheter, we collected an initial series
of blood samples to assess resting blood values in order to moni-
tor the pre- and post-treatment safety corresponding to supple-
mentation with AST. These measures included a standard serum
15-panel blood test to measure creatinine, potassium, uric acid,
albumin, calcium, magnesium, creatine phosphokinase (CPK),
alanine aminotransferase (ALT), alkaline phosphatase (ALK),
iron, cholesterol (LDL & HDL), and triglycerides. We also per-
formed a complete blood count (CBC) with diff erentials to deter-
mine hemoglobin, hematocrit, mean cell volume, platelet count,
white blood count, granulocytes, neutrophils, eosinophils, and
basophils.
After we collected the fi rst set of blood samples we asked each
rider to perform a 10 min warm up at a low intensity (50 W)
before initiating the 2 h ride. During the 2 h pre-load ride we col-
lected blood samples every 20 min to determine several indices
indicative of carbohydrate and lipid metabolism including glu-
cose, lactic acid, glycerol, and non-esterifi ed fatty acids (NEFA).
At these same time intervals we also measured cardiorespira-
tory parameters (VO
2 and VCO
2 , L/min) to determine the relative
contributions of carbohydrate and fat oxidation during testing
using standard stoichiometric equations [ 6 ] . Riders consumed
250 ml of water every 15 min throughout the test. For the blood
measurements we collected each blood sample during the last
30 s of the 20 min period. For VO
2 and VCO
2 we began data col-
lection 4 min before each 20 min demarcation in order to obtain
steady state values. However, we only used the last minute of
this collection period for our analysis. All blood samples were
spun on a centrifuge and stored at − 80 C until we could analyze
them “in batch” (i. e., pre/post test sample together) using a
Beckman Coulter DXC600 (Brea, CA) analyzer.
We analyzed glucose and lactic acid using an oxygen electrode
and enzymatic endpoint method of analysis, respectively. For
glucose, all samples were spun on a centrifuge at 3 500 rpm for
15 min at room temperature. For lactic acid, each sample was
spun at the same speed at 4 °C. For glycerol and NEFA we ana-
lyzed each sample using enzymatic colorimetric detection anal-
ysis, respectively. For glycerol, centrifugation took place at
3 500 rpm for 15 min at room temperature, while for NEFA the
centrifuge speed was 3 000 rpm for 15 min at 4 °C.
Randomization and treatment
After completing the entire baseline testing procedures, we ran-
domized each participant, in a double-blind, placebo controlled,
parallel group designed manner to receive either 4 mg/d of
encapsulated AST or a matched placebo for 4 weeks. We chose
Fig. 2 Overview of study timeline (panel a ) and
testing procedures (panel b ).
a
b
Overview of testing and supplementation timeline.
Baseline Testing
Screening Day 1 Day 2 Day 4 Day 5 Day 32 Day 33 Day 34
2 hr ride
20 km TT
Rest2 hr ride
20 km TT
Rest
VO2max
VO2max
Days 6 – 33
Post TestingSupplement (28 d)
Determine
Eligibility
Ht
Wt
Practice
Time Trial
(20 km)
Day 3
Practice
Time Trial
(20 km)
Sequence of data collection during testing
Pre-Ride procedures 2 hr steady state ride pre-exhaustion ride
Standardized respiratory and blood collections every 20 minutes
Rest
(5 min)
Time
Trial
–30 min –10 – 0 min 16–20 min 36–40 min 56–60 min 76–80 min 96–100 min 116–120 min 120–125 min 125 min+
20 km TT
Respiratory data (4 min of collection)
(VO2 & VCO2)
Measure:
Glucose
Lactic acid
Glycerol
NEFA
Warm up @
100 W
Measure
(–2m):
Glucose
Lactic acid
Glycerol
NEFA
Insert
Catheter
Measure:
Glucose
Lactic acid
Chem-15
CBC
Glycerol
NEFA
Extra
Serum
Plasma
NEFA: Non-esterified fatty acid
TT: Time Trial
PO: Power Output in watts
Ave PO
PO ea. 5 km
Time to
complete
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Earnest CP et al. Astaxanthin Time Trial Performance … Int J Sports Med 2011; 32: 882–888
Nutrition
4 weeks as studies in mice have shown that AST improves lipid
metabolism and exercise performance within a 4–5 week period
[ 2 , 11 ] . All supplements were provided by Fuji Health Science,
Inc. (Burlington, NJ). Each treatment was delivered in a black soft
gel capsule and each AST soft gel contained 80 mg of 5 % natural
astaxanthin extract from Haematococcus pluvialis algae, yielding
4 mg of active astaxanthin per soft gel, and 120 mg of medium
chain triglyceride as fi ller. The placebo soft gel was comprised of
200 mg medium chain triglyceride plus a small amount of cara-
mel food coloring to make the capsules identical in appearance
to the active soft gels. We asked all participants to consume their
respective treatments with a meal and provided each person
with enough supplement for 5 extra days in case they required
an extended period to complete the study protocol. This latter
aspect of our study also better enabled us to perform a pill count
at the end of the study to determine the degree of compliance to
the study protocol. Lastly, people independent of the study dis-
persed all treatments using a unique, individualized 4-digit
number sequence. We chose a randomized number sequence in
case we observed any side eff ects during the course of the study.
This procedure allows for the breaking of a single treatment
code without sacrifi cing the integrity of the entire treatment
cohort.
Statistical analysis
Our primary outcome analysis was aimed at determining
whether AST supplementation improved various indices of
cycling performance following a 2 h pre-exhaustion bout of
exercise intended to minimize carbohydrate contribution. The
primary outcomes for our investigation were the rider’s ability
to complete a 20 km TT immediately following a 2 h pre-exhaus-
tion ride. Accordingly, we examined TT performance in terms of
the time it took to complete the 20 TT km ride and the average
PO generated by the rider. As a secondary analysis we examined
several laboratory indices of physical performance such as
VO
2max , maximal PO, and the PO observed at lactate threshold
(2 mmol/L) and onset of blood lactate accumulation (4 mmol/L)
during the VO
2max test. As a tertiary analysis we assessed several
metabolic parameters traditionally used as a means of providing
a mechanism of action should performance changes be observed.
These indices included the analysis of blood variables indicative
of improved carbohydrate and fat usage including: plasma lac-
tate, glucose, non-esterifi ed fatty acids, and glycerol. We
approached our analysis of these variables in 2 ways. First, we
analyzed the overall eff ectiveness of AST on these variables by
using an integrated area-under-the-curve (AUC) assessment for
all time intervals associated with our data collection beginning
with the resting measurement as “time 0”. Our second strategy
was to examine potential diff erences in these variables at each
20 min time point during the 2 h ride. These specifi c time points
included resting blood values obtained after a 10 h fast, the end
of warm-up, and every 20 min therein during the 2 h ride. Dur-
ing these same time intervals we also examined the respiratory
derived measurements for the stoichiometric assessment of car-
bohydrate and fat oxidation. For our primary analysis we exam-
ined each variable as change from baseline. Determinations for
within group signifi cance were based on the mean change and
accompanying 95 % confi dence interval (95 % CI) for each respec-
tive performance parameter. We used a general linear model to
examine between group diff erences. Eff ect sizes were calculated
for time to complete and average power output during the 20 km
TT using Cohen’s d (ES) [ 4 ] . For the AUC analysis we analyzed our
data using a 2 × 2 [treatment (placebo/treatment) × time (pre/
post)] ANOVA. For the time parameter analysis we used a
repeated measures ANOVA. Lastly, we also examined the mean
change in outcomes between the pre-test and post-test condi-
tion using a one-way ANOVA.
We examined blood chemistry values (i. e., Chem-15/CBC) and
food frequency evaluations using the same statistical techniques
as described for the primary outcome data. The reason for the
blood chemistry analysis was to determine whether AST sup-
plementation might adversely aff ect hepatorenal function, in
order to ensure that supplementation with AST was safe. Lastly,
we examined by pill count the number of assigned treatment
capsules vs. the number of supplement days during the study
period. We excluded any outliers in the studies who fell outside
3 SD for time changes from pre to post treatment. All individual
time point data in our paper are presented as mean ± SD. Statisti-
cal signifi cance was set at P ≤ 0.05.
Results
▼
We randomized 21 participants into our study (AST = 11,
PLA = 10). However, only 7 participants from each treatment
group completed the entire testing protocol. The reasons for this
completion rate are presented in
●
▶
Fig. 1 , but generally fall
under the categories of illness, equipment failure or inability to
complete the 2 h pre-exhaustion ride or the subsequent TT. We
did however remove 2 outlier performances from our analysis.
In one instance, we removed a rider from the AST group for
demonstrating a 7 min time improvement from the pre to post
test condition. In the other instance we removed one rider from
the PLA group for an abnormal performance loss of 5 min.
Though we could have kept these 2 riders in our analysis, their
relative changes in performance given their respective treat-
ment groups, only served to separate our hypothesis further
from the null. In essence, leaving these 2 riders in the analysis
increased the treatment eff ect for the AST group, while simulta-
neously making the PLA group appear slower.
For those who completed the study, we observed no statistical
diff erence at baseline between treatment groups for any of our
measurements associated with the study including age (28 ± 6
years), body mass (74.6 ± 8.8 kg), and height (175.6 ± 8.5 cm). For
our post-test analysis, we observed a signifi cant within group
improvement for the time it took to complete the 20 km TT for
the A ST supplemented riders (2 387 ± 206 s vs. 2 266 ± 190 s;
range, − 02, − 251 s) and the average power output measured
during the TT ride (162 ± 37 W vs. 186 ± 34 W; range, 05–40 W,
P < 0.05). For our analysis of time to complete the 20 km TT, we
observed that the AST group’s time improvement was signifi -
cantly diff erent from the PLA group (P < 0.02). Though some
improvement in time was observed for the PLA group, neither
TT time (2251 ± 260 s vs. 2 233 ± 283 s; range, − 101, 62) or PO
(186 ± 57 W vs. 187 ± 75 W) was statistically signifi cant following
the 28 d supplementation period. The ES for the diff erence
between treatment groups in their time to complete the time
trial was 1.25, whilst the ES for the between group diff erence in
PO was 0.95. According to Cohen, these ES would be considered
large [ 4 ] .We have presented the mean and 95 % CI change for
time and PO along with accompanying individual responses for
each treatment group in
●
▶
Fig. 3 .
For our analysis of fuel utilization we were unable to detect a
signifi cant treatment diff erence for any blood marker indicative
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886
Earnest CP et al. Astaxanthin Time Trial Performance … Int J Sports Med 2011; 32: 882–888
Nutrition
of enhanced carbohydrate or fat oxidation ( ●
▶
Fig. 4 a, b ), neither
were we able to detect a change in any blood parameter sugges-
tive of a shift in fuel metabolism (
●
▶
Fig. 5 a–d ) for any given
20 min time interval. While we did observe a signifi cant increase
in plasma concentrations of NEFA with increasing exercise time,
these increases were similar within each group but not diff erent
between groups or the pre/post treatment condition. When we
further analyzed our blood work data as an AUC for the entire 2 h
pre-exhaustion ride we were also unable to detect a signifi cant
diff erence for treatment group. Lastly, we did not observe any
diff erences in either the blood chemistries suggesting the treat-
ment group signifi cantly altered hepatorenal function during
the treatment period (data not shown).
Discussion
▼
The primary aim of our study was to examine the eff ect of AST
supplementation on 20 km TT performance following a 2 h pre-
exhaustion ride undertaken after a 10 h fast. The goal in using
this type of protocol was to minimize the contributions of carbo-
hydrate for energy provision; hence, creating an increased reli-
ance on fat oxidation. This decision was based on observations
from animal studies showing an increased reliance on fat utiliza-
tion while simultaneously increasing time to exhaustion during
exercise [ 1 , 2 , 11 , 12 ] . We observed an approximate 2 min mean
improvement (5 %) in the time necessary to complete the 20 km
TT that was accompanied by a 20 W increase (15 %) in the aver-
age power output generated by riders during the TT condition.
Changes in time and power output for the PLA group were 0.8 %
and 0.5 %, respectively. An examination of
●
▶
Fig. 3 also shows
that each of the riders in the AST group improved 20 km per-
formance time and power output, while the PLA group showed
minimal improvements and were fairly evenly split between
faster and slower performances. Despite these improvements in
cycling performance the mechanism of action to explain our
fi ndings remain enigmatic.
Most of the research conducted on AST to date has used murine
models to examine exercise performance and energy distribu-
tion patterns. For example, Aoi et al. [ 2 ] examined mice divided
into 4 groups of mice that were either (a) sedentary, (b) seden-
tary, yet, treated with AST, or assigned to run on treadmill (c)
without or (d) with AST supplementation [ 2 ] . In their study, the
authors reported that each exercise group was able to run longer
on the treadmill before exhaustion; however, those mice treated
with AST also increased fat utilization during exercise compared
to mice on a normal diet. At a cellular level these fi ndings were
supported by the observation that AST fed mice increased the
localization of fatty acid translocase (FAT/CD36) and carnitine
palmitoyltransferase I (CPT I) in skeletal muscle. In essence, AST
improved various mechanisms associated with transporting
long chain fatty acids into the mitochondria. In our current
study, however, we see no evidence for the preferential use of
fat.
A question that may be raised pertains to dosing equivalents
between murine and human studies. In one such study, Ikeuchi
Fig. 3 Data represent the mean and 95% CI within group changes in
time performance (panel a ) and power output (panel b ) for cyclists receiv-
ing 28 d of AST (left side) or PLA (right side) supplementation. *P<0.05
for between group diff erences.
300
a
b
–300
250
–250
200
–200
100
–100
50
–50
0
150
–150
60
–60
50
–50
40
–40
20
–20
10
–10
0
30
–30
Time (sec)Power Output (W)
20 W
(95% CI, 1.0,
38.1) 1.6 W
(95% CI, –17,
20.3)
–121 seconds
(95% CI, –185.2,
–56.5)
–19 seconds
(95% CI, –83.5,
45.2)
Astaxanthin Placebo
Astaxanthin Placebo
Fig. 4 Data represent mean and standard deviations for carbohydrate
(panel a ) and fat oxidation (panel b ) observed during the 2 h pre-exhaus-
tion ride.
4.00
a
b
3.00
1.00
3.50
2.50
0.50
0.00
2.00
1.50
0.80
0.60
0.20
0.70
0.50
0.10
0.00
0.40
0.30
Min 20 Min 40 Min 60 Min 80 Min 100 Min 120
Min 20 Min 40 Min 60 Min 80 Min 100 Min 120
Astaxanthin Pre
Astaxanthin Post
Placebo Pre
Placebo Post
Carbo hydrate Oxidation (g/min)Fat Oxidation (g/min)
Astaxanthin Pre
Astaxanthin Post
Placebo Pre
Placebo Post
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887
Earnest CP et al. Astaxanthin Time Trial Performance … Int J Sports Med 2011; 32: 882–888
Nutrition
et al. [ 11 ] examined the eff ects of AST supplementation on exer-
cise-induced fatigue in mice by administering AST (1.2, 6, or
30 mg/kg body weight) for 5 weeks via stomach intubation. Post-
test analysis showed an overall dose dependent increase in exer-
cise time to exhaustion in mice receiving 6 and 30 mg/kg of AST
vs. control. This would equate to approximately 420 mg and 2.1 g
of AST in humans, respectively, assuming the AST was given to a
70 kg “reference male”. Thus, the dosage given to the mice was
signifi cantly higher than what we administered in our study. The
authors of this study also observed a signifi cant reduction in lac-
tic acid and higher concentration of non-esterifi ed fatty acids
and plasma glucose concentrations throughout exercise in the
AST treated groups [ 11 ] . Though this larger dosage pattern may
ultimately aff ect energy substrate utilization, it does not recon-
cile the improvements in performance that we observed in our
trial.
Only two studies have examined the effi cacy of AST for
improving exercise performance in humans, while only one of
those studies examined some type of endurance perform-
ance. In 2 002, Keisuke et al. examined the eff ectiveness of
AST on the build up of lactic acid following 1 200 m of running
before and after 4 weeks of supplementation and found that
the 2 min post-running lactic acid concentration was signifi -
cantly lower in the AST supplemented runners vs. control
[ 14 ] . In a second study, Bloomer et al. supplemented resis-
tance trained men with AST (4 mg/d) for 3 weeks and found no
supplementation related eff ects on plasma levels of creatine
kinase, lactate dehydrogenase, delayed onset muscle soreness
or exercise performance [ 3 ] .
Strengths and Limitations
▼
A strength of our current investigation is that we examined the
eff ectiveness of AST supplementation under conditions aimed at
decreasing the reliance on carbohydrate metabolism by use of
an overnight fast without the presence of CHO ingestion during
the 2 h pre-exhaustion ride. Though we were successful in dem-
onstrating that AST appears to have an ergogenic eff ect, we
acknowledge that the true eff ectiveness of AST supplementation
relative to competitive exercise performance is not yet known
given that our feeding schema does not adequately represent
dietary practices associated with competition. Therefore, to test
the true ergogenic eff ect of a supplement would necessitate
doing so under conditions that best approximate those condi-
tions involved in competition. We further acknowledge that our
results are currently predicated on a relatively small sample size.
One of the strengths of our fi ndings is the observation that all of
the participants in the AST group improved their time in com-
pleting the 20 km TT via an improvement in power output.
Though an examination of the range of improvement varies
from 2 to 251 s, the 95 % confi dence intervals suggest that the
likely range for the true value of the AST treatment is 56–185 s.
Our calculation of eff ect sizes for both performance indices
Fig. 5 Data represent mean and standard deviations for plasma glucose (panel a ), lactic acid (panel b ), non-esterifi ed fatty acid (panel c ) and glycerol
concentrations observed during the 2 h pre-exhaustion ride. *P < 0.05 for within group time point diff erences from rest through 40 min (all groups).
140
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90
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60
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30
20
10
0
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9
8
7
6
5
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2
1
0
1.5
1.4
1.3
1.2
1.1
1
0.9
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1.1
0.9
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0.1
–0.1 Rest Min –10 Min 20 Min 40 Min 60 Min 80 Min 100 Min 120
Rest Min –10 Min 20 Min 40 Min 60 Min 80 Min 100 Min 120
Rest Min –10 Min 20 Min 40 Min 60 Min 80 Min 100 Min 120 Rest Min –10 Min 20 Min 40 Min 60 Min 80 Min 100 Min 120
Astaxanthin Post
Astaxanthin Pre
Placebo Post
Placebo Pre
Glycerol (mmol/L) Nonesterified facty acids (mmol/L)
Lactic Acid (mmol/L) Glucose (mmol/L)
ac
d
b
Astaxanthin Post
Astaxanthin Pre
Placebo Post
Placebo Pre
Astaxanthin Post
Astaxanthin Pre
*
*
Placebo Post
Placebo Pre
Astaxanthin Post
Astaxanthin Pre
Placebo Post
Placebo Pre
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Earnest CP et al. Astaxanthin Time Trial Performance … Int J Sports Med 2011; 32: 882–888
Nutrition
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would be characterized as large by Cohen [ 4 ] . It should also be
noted that our trial using AST accompanied by fasting and with-
out carbohydrate ingestion during the cyclists ride produced
similar results to those of Smith et al., who recently reported
similar fi ndings to ours using carbohydrate supplementation
during a 20 km TT under a similar feeding schema [ 17 ] .
These fi ndings are particularly intriguing as Jeukendrup and
Martin [ 13 ] estimate that carbohydrate and caff eine will pro-
duce similar performance benefi ts in 40 km TT [ 13 ] . For exam-
ple, they project that carbohydrates will improve 40 km TT
performance by 00:42 s, 0:36 s, and 0:32 s for novice, well-
trained, and elite cyclists, respectively. In their model, it has also
been suggested that caff eine improves 40 km TT performance by
1:24 (min:s), 1:03 (min:s), and 0:55 s, respectively. Thus, if one
is to place value on the eff ectiveness of an ergogenic aid during
cycling performance, the results of our study suggest that sup-
plementation with AST may promote similar time gains as to
those noted above using other nutritionally based ergogenic
aids. However, a greater body of conformational research fi nd-
ings needs to be accumulated before making such a conclusion.
Despite our inability to identify a mechanism of action for the
observed changes in exercise performance our study does sug-
gest that AST supplementation may be an eff ective supplement
for improving exercise performance. If fat metabolism is of
future research interest, those investigators undertaking that
task may wish to consider a lower intensity exercise regime
more closely identifi ed with the purported range of maximal fat
oxidation. If performance is an area of interest, we suggest that
these issues be examined under conditions more closely related
to feeding strategies of those athletes engaged in the sport of
interest.
Acknowledgements
▼
Funding for this study was obtained from the Gatorade Sports
Science Institute. Astaxanthin and placebo supplements were
donated by Fuji Health Science, Inc.
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