EAL

NAP: Competition (2007)

Citation:

Anastasiou CA, Kavouras SA, Koutsari C, Georgakakis C, Skenderi K, Beer M, Sidossis LS. Effect of maltose-containing sports drinks on exercise performance. Int J Sport Nutr Exerc Metab. 2004; 14 (6): 609-625.

PubMed ID: 15657468

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 effect of maltose-containing sports drinks on exercise performance, substrate metabolism, hormonal responses and indices of fluid homeostasis during exercise.

Inclusion Criteria:

Healthy male recreational cyclists.

Exclusion Criteria:

Evidence of metabolic, cardiovascular and renal disease
Use of medications
Rapid body weight gain in the previous three months
Blood donation within previous three months.

Description of Study Protocol:

Recruitment

Methods not specified.

Design

Randomized crossover trial.

Blinding Used

Double-blind.

Intervention

Subjects completed four trials separated by at least five days. Each trial consisted of a glycogen-depleting protocol, followed by a 15-minute refueling, after which subjects performed a one-hour performance test while consuming one of the experimental drinks (glucose; maltose; sucrose, maltose or maltodextrin; placebo)
Drinks provided 0.65g CHO per kg of body weight during refueling and 0.2g per kg every 15 minutes during the performance test.

Statistical Analysis

Data were analyzed using ANOVA for repeated measures with two within-subject factors (drink and time) after ensuring for normal distribution of data with Anderson-Darling Normality test
Individual time-points compared using Tukey Honest Significant Difference test
Comparisons in non-normally distributed data performed using logarithmic transformation of data.

Data Collection Summary:

Timing of Measurements

Blood samples collected at the beginning of and every 20 minutes during glycogen depletion protocol as well as at zero, 15, 30 and 45 minutes during cycling and at completion
Expired air samples were collected at 20 and 30 minutes of glycogen depletion and at zero, 15, 30 and 45 minutes into the performance test
RPE and thirst and stomach fullness were assessed at zero, 15, 30 and 45 minutes.

Dependent Variables

Blood samples were analyzed for hematocrit, hemoglobin, lactate, glucose, FFA, insulin, glucagon, cortisol and plasma osmolality
Expired air samples measured with indirect calorimetry
RPE was measured using the Borg scale
Thirst and stomach fullness were measured with visual analog scales.

Independent Variables

Glucose; maltose; sucrose or maltose or maltodextrin; placebo at 0.65g CHO per kg of body weight during refueling and 0.2g per kg every 15 minutes during the performance test.

Control Variables

On day prior to testing, subjects were instructed not to exercise, to drink liberally and to consume a standardized diet (60% CHO).

Description of Actual Data Sample:

Initial N: 10 males
Attrition (final N): 10
Age: Mean age 25.1±2.1 years
Ethnicity: Not mentioned
Location: Greece.

Summary of Results:

Other Findings

Although no significant differences were found in performance (glucose, 67.2±2.0 minutes; maltose, 68.6±1.7 minutes; mixed, 66.7±2.0 minutes; placebo, 69.4±3.0 minutes; P>0.05), subjects completed the mixed CHO trial 3.9% faster than the placebo trial
Carbohydrate drinks caused comparable plasma glucose values that were significantly higher during refueling and at the end of exercise, compared to placebo
There were no significant differences between trials in total CHO oxidation, perceived exertion or stomach fullness.

Author Conclusion:

In conclusion, we detected no performance enhancement with carbohydrate supplementation during an endurance exercise lasting approximately one hour, when performed immediately after a glycogen-depleting exercise
Carbohydrates of high glycemic index produced similar metabolic responses and should be considered of equal effectiveness when consumed during exercise
In addition, when fluid consumption is controlled, fluid balance might not be dependent on fluid composition, at least for the one-hour endurance exercise.

Funding Source:

Industry:

Norvatis Consumer Health (Switzerland)

Food Company:

Reviewer Comments:

Recruitment methods not specified
Power calculations not done
Authors note that the lack of differences may be due to the timing of carbohydrate supplementation and the glycogen-depleting protocol before the performance test.

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?	Yes
	2.2.	Were criteria applied equally to all study groups?	Yes
	2.3.	Were health, demographics, and other characteristics of subjects described?	Yes
	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?		???
	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?	???
	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?	N/A
	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