A L A I N E M I L L SG R A D UAT E T H E SI S D E F E N SE
M A ST E R O F K I N E SI O L O G Y S P O RT S N U T R I T I O N
THE EFFECT OF A BCAA SUPPLEMENT WITH AND WITHOUT CHO ON
PERFORMANCE IN COMPETITIVE CYCLISTS
What are BCAA’s?
Branched-chain amino acids Isoleucine, leucine, and valine Essential amino acids
Account for 35% of the essential amino acids in muscle proteins Endurance exercise increases energy expenditure and
promotes protein and amino acid catabolism BCAAs can be oxidized in skeletal muscles, and their
oxidation is enhanced by exercise (Shimomura, 2004)
Endurance exercise activates the BCKDH complex
BCAAs have been investigated on exercise performance because of their potential in delaying the onset of central fatigue (Greer, White, Arguello, & Haymes, 2011).
BCAA’s Continued
Leucine is the most potent amino acid among the BCAAs for stimulating protein synthesis Supplementation of leucine alone may cause BCAA
imbalance 2:1:1 ratio of leucine, isoleucine, valine (Shimomura, 2004)
A number of research groups examined whether BCAA supplementation might have a beneficial effect on performance (32–36)
Results are inconsistent Additional studies are required to clarify the appropriate
amount of BCAA supplementation for beneficial effects and the responsible mechanisms.
Peripheral Fatigue vs. Central Fatigue in Exercise
Peripheral Fatigue in the muscle Caused mainly by hypoglycemia due to depletion of
muscle glycogen Postponed by carbohydrate (CHO) administration Increase blood glucose, and therefore decreasing glycogen
depletion
Central Mental Fatigue Fatigue in the CNS (i.e. Brain) Possibly due to serotonin release
Central Fatigue Hypothesis
The central fatigue hypothesis is based on the premise that an increase in serotonin levels in the brain during exercise results in the perception of fatigue
Tryptophan, an essential amino acid, is the precursor to serotonin Competes with the BCAAs to cross the blood-brain barrier
A higher concentration of BCAAs in the blood can decrease the amount of tryptophan the cross the BBB, therefore decreasing serotonin Delaying central fatigue
Pre-exercise Supplements
The use of pre-exercise supplements has become an increasingly popular practice among recreational and competitive athletes (Walsh, et al., 2010)
Supplements are particularly useful to athletes who participate in prolonged activities on consecutive days that result in depleted muscle and liver glycogen (Skillen et
al., 2008)
Carbohydrate in combination with protein as a pre-exercise, during exercise, and post-exercise supplement and/or ergogenic aid has been thoroughly investigated in recent research
Research
Past research has shown protein and carbohydrate supplements to positively influence endurance performance
A majority of the studies conducted on these supplements preceding exercise involve a glycogen depletion and resting period prior to supplementation (Berardi, et al., 2008; Ferguson-Stegall, et al., 2010; Howarth, Moreau, Phillips, & Gibala,
2009; Ivy, et al., 2003).
As tapering periods are common during training, this method of testing may not properly represent an athlete’s physical state prior to competition
Purpose Statement
The purpose of the current study was to examine the effect of a BCAA supplement with and without carbohydrate on performance in competitive cyclists
Methods
Subjects (N=6)
College men recruited from the GSU Cycling Club
Subjects were randomly assigned to a treatment order
Each subject completed three double blinded experimental trials separated by at least one week
Table 1. Demographics
Variable Mean ± SD
Age (years) 20.50 ± 1.22
Weight (kg) 72.98 ± 6.78
Height (cm) 174.00 ± 4.20
Vo2 max (ml/kg/min) 59.5 ± 7.9
BMI (kg/m2) 22.8 ± 1.8
Methods
Supplements
*2.5g leucine, 1.25g isoleucine, and 1.25g valine (2:1:1 Ratio)
BCAA BCAA+CHO Placebo
1 Teaspoon BCAA Powder (5g)*
1 Teaspoon BCAA Powder (5g)*
--
500 ml Powerade Zero
500ml 6% CHO Powerade (30g)
500 ml Powerade Zero
20 calories 140 calories 0 calories
Methods
VO2 Max test Each subject’s maximal oxygen uptake (VO²max) was
determined on an electrically braked cycle ergometer (Parvo Medics' TrueOne® 2400)
Computerized metabolic cart that measures inspiration and expiration gas exchange variables
Subjects were tested in a 3- hour fasted state
Validity and reliability (Bassett DR, 2001; Crouter SE, 2006)
Graded test Began to cycle at 100 watts Watts increased by 25 every minute until volitional exhaustion
was reached Heart rate was obtained using a polar heart rate monitor
Methods
Time to Exhaustion Test Subjects were instructed to avoid food, tobacco,
alcohol, and caffeine for 12 hours prior to taking the test
Fitted with a mouthpiece, nose clip, and headgear A polar heart rate strap with a sensor fitted around
the subject’s chest Subjects consumed the supplement and then rested
for 10 minutes
Performance Measurement
Timed cycle to exhaustion 10 minutes after consuming the test drink 2 minute warm up at 100 watts 80% Vo2 max until exhaustion
Individualized Wattage increased in 2 increments Self- selected pedal cadence
between 70 and 100 RPM A warning was given when their cadence dropped by ≥
10 r/min for more than 20 seconds The second time this occurred, the trial was terminated
Perceived Performance Measurement
Ratings of Perceived Exertion Validated Borg 1-10
RPE scale Taken every 3 minutes
during the experimental trial
Averages were used for data analysis
Hypothesis # 1
Subjects receiving CHO + BCAA will significantly improve time to exhaustion when compared to BCAA and placebo
Statistical Analysis:
ANOVA with Repeated Measures
IV = Supplement group (BCAA, BCAA+CHO, PL)
DV = Time to exhaustion
Alpha= 0.05
Hypothesis # 2
Subjects receiving CHO + BCAA will demonstrate significantly lower average RPE scores during exercise when compared to BCAA and placebo
Statistical Analysis:
ANOVA with Repeated Measures
IV = Supplement group (BCAA, BCAA+CHO, PL)
DV = Average RPE score during exercise
Alpha= 0.05
Results
Hypothesis #1 Cycling time to exhaustion was not significantly
different between trials, F(2,10) = .224, p > 0.05.
Placebo BCAA BCAA+CHO12.9
13
13.1
13.2
13.3
13.4
13.5
13.6
13.7
13.8
Mean Time to Exhaustion (min)
Results
Hypothesis #2 Average ratings of perceived exertion were not
significantly different between trials, F(2,10) = 4.026, p = .052. There was a trend toward a lower RPE during BCAA
RPEplacebo RPEbcaa RPEbcaacho5.6
5.8
6
6.2
6.4
6.6
6.8
7
7.2
Average RPE
Discussion
The main finding in the study was that the addition of carbohydrate to a drink containing branched-chain amino acids did not alter time to exhaustion or ratings of perceived exertion during the ride.
These results suggest that the ingestion of BCAA’s prior to high-intensity exercise does not improve performance or perceived performance.
Discussion
Amount of CHO 6% solution or 30g of CHO per supplement Could have been to0 low
Higher use of CHO at the higher intensity (80%Vo2 max) Not individualized by body weight
Amount of BCAA’s 5g per supplement or a standard serving size Previous studies have shown significance with similar
or higher amounts Ratio of BCAA’s
2:1:1 leucine:isoleucine:valine Still undetermined which ratio is most effective
Discussion
Many studies finding improved time to exhaustion used whole protein sources rather than BCAA’s only Ivy et al. (2003), Saunders et al (2004), Niles et al.
(2001), Martinez-Lagunas et al. (2010), Ferguson-Stegall et al. (2010)
Supplementing complete protein source (i.e. whey) may have a better effect on time to exhaustion
Discussion
Trend toward lower RPE during BCAA Could be due to delayed central fatigue in the brain
Decreased Tryptophan:BCAA ratio Unable to determine without blood analysis
Several studies have found similar results (Blomstrand, 1997; Greer, 2011; Hsu, 2011) Demonstrated lower perceived exertion during exercise when
supplemented BCAA’s Found increased plasma BCAA’s and an decreased
Tryptophan:BCAA ratio
RPE during BCAA+CHO Intake of CHO can delay the increase in concentration of
free tryptophan Therefore delaying central fatigue
Discussion
Lack of dietary control Glycogen stores could have influenced performance
There is evidence that higher than normal pre-exercise muscle glycogen contents increase the time to exhaustion and performance (Bussau, 2002).
Low CHO diet prior could result in especially low glycogen levels causing a decrease in performance.
High CHO diet prior could result in increased performance due to supersaturating the glycogen stores.
Having subjects consume a standardized diet the day before the trials would be ideal
Discussion
Future Research Amount of BCAA’s and ratio of
isoleucine:leucine:valine Could be supplemented during exercise
Standardized diets for subjects Blood analyses
Plasma BCAA Tryptophan:BCAA Plasma glucose & insulin
Lower % of VO2 max
Conclusion
Consuming a pre-exercise supplement containing BCAA’s with or without CHO did not appear to have an effect on performance or perceived performance in competitive cyclists
Additional research is needed
Limitations
Limitations
Sample selection was non-randomized
Small sample size
Lack of dietary control
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