EAL

NAP: Recovery (2007)

Citation:

Nicholas CW, Green PA, Hawkins RD, Williams C. Carbohydrate intake and recovery of intermittent running capacity. Int J Sport Nutr. 1997 Dec; 7 (4): 251-260.

PubMed ID: 9407252

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 investigate if extra calories as CHO, after exhaustive intermittent running, could restore running capacity within 22 hours, as compared to extra calories as protein and fat.

Inclusion Criteria:

Not stated.

Exclusion Criteria:

Not stated.

Description of Study Protocol:

Recruitment: Not stated
Design: Counter-balanced, crossover trial with order of diet randomly assigned
Blinding used: Not stated

Intervention

There were four trials performed under two dietary conditions: Trials One and Two under the CHO condition and Trials Three and Four under the Control condition
There was a 22-hour recovery period between Trials One and Two and Trials Three and Four
Trials Three and Four were conducted seven days after Trials One and Two
Trial One was used to assess running capacity
Trial Two was performed after administration of the CHO or control diet
Within 20 minutes of Trials One and Three, for both dietary conditions, all subjects were provided with a 6.9% CHO-electrolyte drink and breakfast. The CHO content of the breakfast differed from the Control group (122g CHO vs. 18g CHO)
The diet was prescribed by a dietitian using the food exchange system and was based on the diet calculated from two-day weighed food records
CHO was added to the individual daily intake to reach 10g per kg of body mass.

Statistical Analysis

Two-way ANOVA for repeated measures
Student's paired T-test.

Data Collection Summary:

Timing of Measurements

The first and second trial for each condition were separated by a 22-hour recovery
The second set of trials was completed one week after the first set.

Dependent Variables

VO_2max (estimated by progressive 20-meter shuttle run test)
Heart rate (short-range telemetry)
Running time (minutes)
Blood samples were analyzed for lactate and glucose.

Independent Variables

Macronutrient content of the breakfast (112g CHO vs. 18g CHO) with the same number of kcals.

Description of Actual Data Sample:

Initial N: Six males
Attrition (final N): Six males
Age: 21.8±0.7 years (mean±SEM)
Ethnicity: Not stated.

Other Relevant Demographics

Height: 174.4±4cm
Body mass: 70.5±4.2kg
Maxmimal oxygen uptake: 56±0.9kg per minute
Men had at least five years experience playing soccer, rugby, hockey or basketball and their weekly training and playing time ranged between five and eight hours
Location: London.

Summary of Results:

Other Findings

After the CHO recovery diet, subjects ran for 3.3±1.1 minutes longer during Time Two than Time One (P<0.05) and 7.4 minutes longer than their perfomance during Time Two, following the Control recovery diet (P<0.01)
When the differences in performance times between Time One and Time Two were compared across experimental conditions, subjects ran for 5.8±1.7 minutes longer in the CHO trial (P<0.05)
For the CHO trial, subjects covered a distance of 13.2km and 13.8km for Trials One and Two, respectively (P<0.05)
In the Control trial, the total distance was 12.9km for Time One and 12.4km for Time Two (P=NS)
Subjects ran a further 1.1±0.3km (P<0.05), when the differences in performance times between Time One and Time Two were compared between treatments
No differences in blood glucose, blood lactate or heart rate were reported
Running capacity was not only restored in the 22-hour recovery period in the CHO group, but it was improved. No such improvement was observed in the Control group.

Author Conclusion:

In summary, increasing the carbohydrate intake of a normal diet to 10g per kg of body mass per day improves intermittent high-intensity running capacity after 22 hours of recovery
This study confirms the need for increased CHO intake, so that athletes participating in prolonged intermittent high-intensity exercise can compete and train optimally on a daily basis.

Funding Source:

Industry:

Smith Klein-Beecham

Pharmaceutical/Dietary Supplement Company:

Reviewer Comments:

Inclusion criteria, exclusion criteria and recruitment methods not defined.

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?	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?		???
	5.1.	In intervention study, were subjects, clinicians/practitioners, and investigators blinded to treatment group, as appropriate?	???
	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.)	???
	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?	???
	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?		Yes
	10.1.	Were sources of funding and investigators' affiliations described?	???
	10.2.	Was the study free from apparent conflict of interest?	Yes