EAL

NAP: Competition (2007)

Citation:

Davis JM, Welsh RS, De Volve KL, Alderson NA. Effects of branched-chain amino acids and carbohydrate on fatigue during intermittent, high-intensity running. Int J Sports Med. 1999; 20: 309-314.

PubMed ID: 10452228

Study Design:

Randomized crossover trial

Class:

A - Click here for explanation of classification scheme.

Quality Rating:

NEUTRAL: See Quality Criteria Checklist below.

Research Purpose:

To examine the effects of ingesting carbohydrate beverages with and without branched chain amino acids before and during intermittent high-intensity running to fatigue.

Inclusion Criteria:

Subjects were screened for health and activity status and were informed about the nature of the experimental procedures and possible risks involved.

Exclusion Criteria:

None specifically mentioned.

Description of Study Protocol:

Recruitment: Recruited from university setting
Design: Randomized crossover trial
Blinding used: Double-blind.

Intervention

Subjects performed three exercise trials, separated by one week, consisting of intermittent shuttle-running (walking, sprinting and running) to fatigue
Subjects drank either carbohydrate drinks given one hour before (five ml per kg, 20% carbohydrate) and during exercise (two ml per kg, 6% carbohydrate), carbohydrate drinks with branched-chain amino acids (seven grams) added to the portions consumed one hour before and during exercise or flavored water placebos.

Statistical Analysis

Exercise performance data was analyzed using one-way ANOVA procedures
Blood variables and heart rate data were analyzed using two-way ANOVA with repeated measures (treatment by time)
When significant main effects or interactions were found, a Duncan's post-hoc test was utilized.

Data Collection Summary:

Timing of Measurements

Blood samples were collected 10 minutes prior to exercise, following each 15-minute bout of exercise (15, 30, 45, 60, 75 minutes) and at fatigue
Heart rate was measured every 15 seconds.

Dependent Variables

Exercise performance was measured through run time to fatigue
Blood samples were analyzed for lactate, hematocrit, hemoglobin, glucose, insulin and FFA
Heart rate was measured using telemetry.

Independent Variables

Either carbohydrate drinks given one hour before (five ml per kg, 20% carbohydrate) and during exercise (two ml per kg, 6% carbohydrate), carbohydrate drinks with branched-chain amino acids (seven grams) added to the portions consumed one hour before and during exercise or flavored water placebos
Subjects asked to maintain normal activity levels for 24 hours prior and follow same dietary patterns.

Description of Actual Data Sample:

Initial N: Eight subjects, three male, five female
Attrition (final N): Eight
Age: Not mentioned
Ethnicity: Not mentioned
Location: South Carolina.

Summary of Results:

Other Findings

Subjects ran longer when fed either carbohydrates (9.66 minutes) or carbohydrates with BCAA (9.00 minutes), as compared to placebo (6.36 minutes) with no differences between carbohydrates and carbohydrates with BCAA
Heart rate and blood lactate were not significantly different between trials
Carbohydrates and carbohydrates with BCAA also had higher plasma glucose and insulin and lower FFA (P<0.05).

Author Conclusion:

In conclusion, data presented in this study suggests that ingestion of carbohydrate beverages, one hour prior to and throughout exercise, delays fatigue during intermittent high-intensity exercise. This observation has practical implications for those who participate in sports such as soccer, basketball, tennis and hockey since the activity pattern used in this experiment is similar to that which occurs in those sports. The addition of BCAA to the carbohydrate drinks, however does not appear to provide any additional benefit.

Funding Source:

University/Hospital:

University of South Carolina

Reviewer Comments:

Inclusion and exclusion criteria and subjects were not well-described
No power calculations were done
Authors note that there was no way to distinguish potential benefits of the pre-exercise meal.

Quality Criteria Checklist: Primary Research
Relevance Questions
	1.	Would implementing the studied intervention or procedure (if found successful) result in improved outcomes for the patients/clients/population group? (Not Applicable for some epidemiological studies)	Yes
	2.	Did the authors study an outcome (dependent variable) or topic that the patients/clients/population group would care about?	Yes
	3.	Is the focus of the intervention or procedure (independent variable) or topic of study a common issue of concern to dieteticspractice?	Yes
	4.	Is the intervention or procedure feasible? (NA for some epidemiological studies)	Yes

Validity Questions
1.	Was the research question clearly stated?		Yes
	1.1.	Was (were) the specific intervention(s) or procedure(s) [independent variable(s)] identified?	Yes
	1.2.	Was (were) the outcome(s) [dependent variable(s)] clearly indicated?	Yes
	1.3.	Were the target population and setting specified?	Yes
2.	Was the selection of study subjects/patients free from bias?		???
	2.1.	Were inclusion/exclusion criteria specified (e.g., risk, point in disease progression, diagnostic or prognosis criteria), and with sufficient detail and without omitting criteria critical to the study?	No
	2.2.	Were criteria applied equally to all study groups?	No
	2.3.	Were health, demographics, and other characteristics of subjects described?	No
	2.4.	Were the subjects/patients a representative sample of the relevant population?	???
3.	Were study groups comparable?		Yes
	3.1.	Was the method of assigning subjects/patients to groups described and unbiased? (Method of randomization identified if RCT)	Yes
	3.2.	Were distribution of disease status, prognostic factors, and other factors (e.g., demographics) similar across study groups at baseline?	Yes
	3.3.	Were concurrent controls or comparisons used? (Concurrent preferred over historical control or comparison groups.)	Yes
	3.4.	If cohort study or cross-sectional study, were groups comparable on important confounding factors and/or were preexisting differences accounted for by using appropriate adjustments in statistical analysis?	N/A
	3.5.	If case control study, were potential confounding factors comparable for cases and controls? (If case series or trial with subjects serving as own control, this criterion is not applicable.)	N/A
	3.6.	If diagnostic test, was there an independent blind comparison with an appropriate reference standard (e.g., "gold standard")?	N/A
4.	Was method of handling withdrawals described?		Yes
	4.1.	Were follow-up methods described and the same for all groups?	Yes
	4.2.	Was the number, characteristics of withdrawals (i.e., dropouts, lost to follow up, attrition rate) and/or response rate (cross-sectional studies) described for each group? (Follow up goal for a strong study is 80%.)	Yes
	4.3.	Were all enrolled subjects/patients (in the original sample) accounted for?	Yes
	4.4.	Were reasons for withdrawals similar across groups?	N/A
	4.5.	If diagnostic test, was decision to perform reference test not dependent on results of test under study?	N/A
5.	Was blinding used to prevent introduction of bias?		Yes
	5.1.	In intervention study, were subjects, clinicians/practitioners, and investigators blinded to treatment group, as appropriate?	Yes
	5.2.	Were data collectors blinded for outcomes assessment? (If outcome is measured using an objective test, such as a lab value, this criterion is assumed to be met.)	Yes
	5.3.	In cohort study or cross-sectional study, were measurements of outcomes and risk factors blinded?	N/A
	5.4.	In case control study, was case definition explicit and case ascertainment not influenced by exposure status?	N/A
	5.5.	In diagnostic study, were test results blinded to patient history and other test results?	N/A
6.	Were intervention/therapeutic regimens/exposure factor or procedure and any comparison(s) described in detail? Were interveningfactors described?		Yes
	6.1.	In RCT or other intervention trial, were protocols described for all regimens studied?	Yes
	6.2.	In observational study, were interventions, study settings, and clinicians/provider described?	N/A
	6.3.	Was the intensity and duration of the intervention or exposure factor sufficient to produce a meaningful effect?	Yes
	6.4.	Was the amount of exposure and, if relevant, subject/patient compliance measured?	Yes
	6.5.	Were co-interventions (e.g., ancillary treatments, other therapies) described?	Yes
	6.6.	Were extra or unplanned treatments described?	Yes
	6.7.	Was the information for 6.4, 6.5, and 6.6 assessed the same way for all groups?	Yes
	6.8.	In diagnostic study, were details of test administration and replication sufficient?	N/A
7.	Were outcomes clearly defined and the measurements valid and reliable?		Yes
	7.1.	Were primary and secondary endpoints described and relevant to the question?	Yes
	7.2.	Were nutrition measures appropriate to question and outcomes of concern?	Yes
	7.3.	Was the period of follow-up long enough for important outcome(s) to occur?	Yes
	7.4.	Were the observations and measurements based on standard, valid, and reliable data collection instruments/tests/procedures?	Yes
	7.5.	Was the measurement of effect at an appropriate level of precision?	Yes
	7.6.	Were other factors accounted for (measured) that could affect outcomes?	Yes
	7.7.	Were the measurements conducted consistently across groups?	Yes
8.	Was the statistical analysis appropriate for the study design and type of outcome indicators?		???
	8.1.	Were statistical analyses adequately described and the results reported appropriately?	Yes
	8.2.	Were correct statistical tests used and assumptions of test not violated?	Yes
	8.3.	Were statistics reported with levels of significance and/or confidence intervals?	Yes
	8.4.	Was "intent to treat" analysis of outcomes done (and as appropriate, was there an analysis of outcomes for those maximally exposed or a dose-response analysis)?	N/A
	8.5.	Were adequate adjustments made for effects of confounding factors that might have affected the outcomes (e.g., multivariate analyses)?	N/A
	8.6.	Was clinical significance as well as statistical significance reported?	Yes
	8.7.	If negative findings, was a power calculation reported to address type 2 error?	No
9.	Are conclusions supported by results with biases and limitations taken into consideration?		Yes
	9.1.	Is there a discussion of findings?	Yes
	9.2.	Are biases and study limitations identified and discussed?	Yes
10.	Is bias due to study's funding or sponsorship unlikely?		Yes
	10.1.	Were sources of funding and investigators' affiliations described?	Yes
	10.2.	Was the study free from apparent conflict of interest?	Yes