EAL

NAP: Recovery (2007)

Citation:

Haub MD, Haff GG, Potteiger JA. The effect of liquid carbohydrate ingestion on repeated maximal effort exercise in competitive cyclists. J Strength Cond Res. 2003; 17: 20-25.

PubMed ID: 12580651

Study Design:

Randomized Controlled Trial

Class:

A - Click here for explanation of classification scheme.

Quality Rating:

NEUTRAL: See Quality Criteria Checklist below.

Research Purpose:

The purpose of the study was to:

Examine the effect of carbohydrate ingestion during a 60-minute recovery between short-duration time trials on subsequent time trial performance in competitive cyclists
Assess the effect of carbohydrate ingestion on the concentrations of plasma glucose and non-esterified fatty acids and lactate.

Inclusion Criteria:

The participants were included if they had trained at least five days per week for six months before testing, achieved a VO_2peakabove 4.0L per minute and were certified US Cycling Federation cyclists (category four to professional).

Exclusion Criteria:

None stated.

Description of Study Protocol:

Recruitment: Not stated
Design: Randomized, counter-balanced trial
Blinding used: Authors state the study was double-blind, but no other information provided.

Intervention

Three testing occasions:

Initial test was to determine VO_2peak and familiarize with the test protocol
Testing sessions two and three: The intervention included a 100-kJ test (Ride One), ingestion of one of the two beverages (Gatorade or placebo), a 60-minute rest, a second 100-kJ test (Ride Two). Testing sessions were conducted between three and seven days apart.
After Ride One, the participant consumed the treatment intervention (20% solution of 0.7g/kg of maltodextrin (Gatorade) or an equal volume of liquid matched for sweetness with aspartame.

Statistical Analysis

A two-way repeated measures analysis of variance was used to examine effects between treatments and a T-test was used to assess within-treatment differences.

Data Collection Summary:

Timing of Measurements

Blood was collected:

Before Ride One
After Ride One
After ingesting the intervention liquid and resting 60 minutes
After Ride Two.

Dependent Variables

Time to complete the 100-KJ test
Aerobic power (VO_2max).

Independent Variables

Liquid CHO drink or placebo drink.

Control Variables

Food records were self-recorded for the day before and day of each treatment to assess total energy and carbohydrates.

Description of Actual Data Sample:

Initial N: Seven males
Attrition (final N): Seven males
Age: 23±3 years
Ethnicity: Not stated
Other relevant demographics: None stated

Anthropometrics

Mean weight: 73.3±4.3kg
Mean height: 1.81±0.02m
Peak oxygen consumption: 4.8±0.5L per minute.

Location

University of Kansas.

Summary of Results:

Variables	Ride One (Mean, SD)	Ride Two (Mean, SD)	Statistical Significance of Group Difference
Time
CHO	270.3±29.0	271.7±26.6	Not significant
Placebo	269.9±33.0	275.3±30.6	Not significant
VO_2max
CHO	4.39±0.30	4.41±0.30	Not significant
Placebo	4.37±0.4	4.32±0.30	Not significant

Other Findings

The liquid CHO resulted in significant changes between treatments for plasma glucose and non-esterified fatty acids, but not for lactate, compared to the placebo.

Author Conclusion:

Ingesting CHO had no significant effect between or within treatments on time or VO₂.

Funding Source:

Industry:

Gatorade Sport Science Institute

Food Company:

Reviewer Comments:

Recruitment and selection was not discussed in the manuscript.

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?		No
	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?	???
	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?		???
	3.1.	Was the method of assigning subjects/patients to groups described and unbiased? (Method of randomization identified if RCT)	No
	3.2.	Were distribution of disease status, prognostic factors, and other factors (e.g., demographics) similar across study groups at baseline?	???
	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?		No
	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%.)	???
	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?	No
	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?		Yes
	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)?	Yes
	8.5.	Were adequate adjustments made for effects of confounding factors that might have affected the outcomes (e.g., multivariate analyses)?	Yes
	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?		???
	10.1.	Were sources of funding and investigators' affiliations described?	Yes
	10.2.	Was the study free from apparent conflict of interest?	???