EAL

NAP: Recovery (2007)

Citation:

Wong SH, Williams C, Adams N. Effects of ingesting a large volume of carbohydrate-electrolyte solution on rehydration during recovery and subsequent exercise capacity. Int J Sport Nutr Exerc Metab. 2000 Dec; 10 (4): 375-393.

PubMed ID: 11099366

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 rehydration and rehydration + carbohydrate ingestion during four hours of recovery on endurance-running capacity.

Inclusion Criteria:

Not stated.

Exclusion Criteria:

Not stated.

Description of Study Protocol:

Recruitment: Not stated.
Design: Randomized, crossover design
Blinding used: Double-blind.

Intervention

Two treadmill runs at 70% VO_2max, separated by four hours of recovery and conducted at least seven days apart
In Trial One, the participant ran for 90 minutes
During the first three hours of recovery, participants drank a CHO-electrolyte solution or a placebo every 30 minutes.

Statistical Analysis

ANOVA for repeat measures on two factors (experimental treatment and time)
Student's T-tests were used to compare paired data
Tukey's post-hoc test to identify differences between means when a significant interaction was identified.

Data Collection Summary:

Timing of Measurements

Two treadmill runs at 70% VO_2max, separated by four hours of recovery and conducted at least seven days apart.

Dependent Variables (Athletic Performance)

Time to exhaustion
Percentage VO_2max, RR and CHO oxidation rate
Body mass changes
Fluid balance
Urine output
Changes in plasma volume
Blood metabolites
Temperature
Heart rate, perceived rate of exertion, thirst.

Independent Variables (Dietary Manipulation)

Each subject prescribed fluid equivalent to 200% of body mass lost during T1 in both experimental trials
The fluid was either the CHO-electrolyte drink or electrolyte-free sweetened drink (not all sujects were able to consume this amount).

Control Variables (Not Used in Analysis, but Collected)

Three-day weighted food record collected prior to first run
Participants were required to consume the same diet three days before the second run
The diet data were not used in the analysis.

Description of Actual Data Sample:

Initial N: Nine endurance trained male athletes
Attrition (final N): Nine
Age: 26.4±1.7 years (mean±SEM)
Ethnicity: Not stated.
Other relevant demographics: None stated.

Anthropometrics (Mean±SEM)

Height: 178.5±2.5cm
Body mass: 71.0±2.7kg
Maximum heart rate: 189±3 beats per minute
Maximal oxygen uptake: 59.5±1.5ml per kg per minute.

Location

Loughborough University, Leicestershire, UK.

Summary of Results:

Variables	Carbohydrate	Placebo	Statistical Significance of Group Difference
Time to exhaustion during Time Two (minutes)	69.3±5.5	45.0±4.2	P<0.01

Other Findings

During Time Two, run time in the CHO condition was 24.3±4.4 minutes longer than the placebo
Higher blood glucose concentrations were observed throughout recovery in the CHO condition.

Author Conclusion:

In conclusion, positive fluid balance can be achieved by ingesting a prescribed volume of either a 6.9%-CHO-electrolyte solution or a CHO-electrolyte-free sweetened placebo, during a four-hour recovery, when the runners ingested the equivalent of approximately 170% of the body fluid lost
Despite a similar hydration status after the recovery in both conditions, ingesting a CHO-electrolyte solution was more effective in restoring endurance capacity, compared to the same volume of placebo solution.

Funding Source:

University/Hospital:

Chinese University of Hong Chong, Loughbrough University (UK)

Reviewer Comments:

Inclusion criteria, exclusion criteria and recruitment methods were not specified.

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?	???
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?	???
	2.2.	Were criteria applied equally to all study groups?	???
	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?		N/A
	3.1.	Was the method of assigning subjects/patients to groups described and unbiased? (Method of randomization identified if RCT)	N/A
	3.2.	Were distribution of disease status, prognostic factors, and other factors (e.g., demographics) similar across study groups at baseline?	N/A
	3.3.	Were concurrent controls or comparisons used? (Concurrent preferred over historical control or comparison groups.)	N/A
	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?	N/A
	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?	???
	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?	???
	7.6.	Were other factors accounted for (measured) that could affect outcomes?	???
	7.7.	Were the measurements conducted consistently across groups?	???
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)?	???
	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?	N/A
9.	Are conclusions supported by results with biases and limitations taken into consideration?		???
	9.1.	Is there a discussion of findings?	Yes
	9.2.	Are biases and study limitations identified and discussed?	No
10.	Is bias due to study's funding or sponsorship unlikely?		???
	10.1.	Were sources of funding and investigators' affiliations described?	No
	10.2.	Was the study free from apparent conflict of interest?	No