Hydration and Physical Activity
Citation:
Study Design:
Class:
- Click here for explanation of classification scheme.
Quality Rating:
Research Purpose:
To examine ingestion of differing levels of CHO during a four-hour recovery after prolonged running on subsequent running capacity.
Inclusion Criteria:
Not stated.
Exclusion Criteria:
Not stated.
Description of Study Protocol:
- Recruitment: Not stated.
- Design: Randomized crossover trial
- Blinding used: Double-blind.
Intervention
- Preliminary test was used to assess VO2max and familiarize participant with protocol
- Two trials, each consisting of two treadmill runs, spearated by at least seven days: Trial One consisted of a 90-minute run
- The four-hour recovery period began after Trial One. A fixed volume of 150% of body mass lost during Trial One was consumed during recovery on both occasions.
Statistical Analysis
- Student's T-test was used to analyze paired data
- Two-way ANOVA for repeated measures on two factors (experimental treatment and time)
- Tukey's post-hoc test was used to assess differences between means if a significant interaction was detected.
Data Collection Summary:
Timing of Measurements
70% VO2max run on treadmill for 90 minutes, followed by four-hour recovery and run to exhaustion at same speed on two occasions.
Dependent Variables
- Performance time
- Total volume ingested
- Percentage rehydration
- Changes in body mass
- Blood samples analyzed for insulin, lactate, glucose.
Independent Variables
- CHO or placebo beverage
- In both conditions, participants consumed 770ml of 6.5% CHO 30 minutes after Trial One. Participants then consumed the CHO or placebo (CHO-free sweetened beverage) at 30 minutes for three hours during recovery (167g CHO vs. 59g CHO).
Control Variables
- Three-day weighed diet records were collected and analyzed
- Subjects were asked to eat the same diet during the same time before the second experiment.
Description of Actual Data Sample:
- Initial N: Nine endurance-trained male runners
- Attrition (final N): Nine
- Mean age (±SEM): 34.3±2.4 years
- Ethnicity: Not stated.
Other Relevant Demographics (Mean±SEM)
- Height: 180.0±1.5cm
- Mass: 70.4±2.7kg
- Maximum heart rate: 185±3 beats per minute
- V02max: 58.9±2.3ml per kg per minute.
Location
Not stated.
Summary of Results:
Variables |
Carbohydrate |
Placebo (Mean±SEM) |
Statistical Significance of Group Difference |
Run Time in Time Two (minutes) |
56.9±8.1 |
65.4±7.8 |
NS |
Other Findings
- Higher blood glucose and serum insulin concentrations were observed during recovery in the CHO trial (P<0.05)
- The estimated contributions of CHO oxidation to total energy expenditure during Time One in the CHO and placebo trials were 55.8% and 54.6%, respectively (not significant)
- During Time Two, the same estimations suggested that a greater proportion of the total energy expenditure was provided by CHO oxidation in the CHO trial (75.8%) than in the placebo trial (50.2%, P<0.05).
Author Conclusion:
- In summary, the results of this study suggest that ingestion of 50g CHO immediately after prolonged exercise results in a similar endurance capacity after a four-hour recovery, as ingesting three times more CHO (approximately 167g CHO) over the same recovery period in rehydrated subjects
- No differences in endurance running capacity after a four-hour recovery, when runners ingested either 167g or 59g of CHO.
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
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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? | No | |
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? | 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)? | ??? | |
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? | 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? | No | |
10.2. | Was the study free from apparent conflict of interest? | Yes | |