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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