EAL

NAP: Training (2014)

Citation:

Erith S, Williams C, Stevenson E, Chamberlain S, Crews P, Rushbury I. The Effect of High Carbohydrate Meals with Different Glyecemic Indices on Recovery of Performance During Prolonged Intermittent High-Intensity Shuttle Running. Int J Sports Nutr Exerc Metab. 2006; 16 (4): 393-404.

PubMed ID: 17136941

Study Design:

Randomized Crossover Trial

Class:

A - Click here for explanation of classification scheme.

Quality Rating:

NEUTRAL: See Quality Criteria Checklist below.

Research Purpose:

The purpose of the present study was to examine the effect of high-CHO meals with different GI values on 22-hour recovery from prolonged intermittent high-intensity shuttle running.

Inclusion Criteria:

No details given regarding inclusion and exclusion criteria or recruitment
Seven semi-professional soccer players participated in the study and gave informed written consent.

Exclusion Criteria:

None stated.

Description of Study Protocol:

Recruitment

No recruitment methods stated.

Design

Seven male semi-professional soccer players particiated in two experimental trials in a randomized cross-over design completed over two days and separated by seven to 10 days
Subjects arrived in a fasting state, having recorded their meals for the previous two days. This was so they could eat the same food before the next trial seven to 10 days later.

Blinding Used

None stated.

Intervention

Each trial was as follows: On Day One (R1), the subjects performed 90 minutes of an intermittent high-intensity shuttle running protocol [Loughborough Intermittent Shuttle Test (LIST)]
They then consumed a mixed high-carbohydrate recovery diet (8g per kg body mass) consisting of either high- (HGI; GI, 70) or low-GI (LGI; GI, 35) foods, depending on which trial they were in
On Day Two, 22 hours later (R2), the subjects again arrived in a fasting state and completed 75 minutes of the LIST (part A) followed by alternate sprinting and jogging to fatigue (part B)
Seven to 10 days later, the subject underwent the same trial with either low- or high-glycemic recovery diet, whichever one they did not receive during the first trial.

Statistical Analysis

Analysis of Variance (ANOVA) with repeated measures was used to examine differences in physiological and metabolic differences in Part A
Student's paired T-test was used to analyze differences in point of fatigue (Part B)
Statistical significance at P<0.05.

Data Collection Summary:

Timing of Measurements

The two trials were separated by 7-10 days
Each trial was completed over 2 days
2 days before the trial participants were asked to abstain from alcohol and caffeine and strenuous exercise
Subjects arrived on the day of the trial in a fasting state.
Blod sampling via cannula were taken every 15 minutes
Subjects were given the same amount of water, based on body weight, before and during exercise.
Subjects were given breakfast 30 minutes after LIST, lunch 3 hours later, both in the lab. Snacks and dinner were provided to be eaten at home at specific times

Dependent Variables

Run time to exhaustion
Heart rate and rating of perceived exertion (RPE)
Hydration Status
Plasma free fatty acids (FFA) and glycerol
Plasma glucose and serum insulin responses
Blood lactate

Independent Variables

High-glycemic index meals and Low-glycemic index meals

Control Variables

Environmental conditions (temperature and humidity)
Diet in the preceding two days

Description of Actual Data Sample:

Initial N: Seven males
Attrition (final N): Seven
Age: 23±2 years
Ethnicity: Not stated
Other relevant demographics
- ?Maximal oxygen uptake level: 58±0.8ml*kg^-1*min^-1.
Anthropometrics
- Body mass: 73.7±9kg
- Location: UK.

Summary of Results:

Key Findings

Run time: No differences found in run time to exhaustion, fatigue index, number of sprints or total distance in R2, Part B between the two trials
Heart rate and rating of perceived exhaustion: No differences found between the two trials
Hydration status
- No differences found in body mass between the two trials
- No differences found in pre-exercise urine osmolality between the two trials (does not appear they tested post-exercise urine osmolality).
Plasma FFA and glycerol: No differences found between the two trials
Plasma glucose and serum insulin: Plasma glucose concentartions rose and serum insulin concentration decreased at the same rate between the two trials at the start of exercise and were maintained at the same levels between the two trials during point of fatigue (R2, Part B)
Blood lactate: No differences observed between the two trials.

Author Conclusion:

The main finding of the present study was that a HGI carbohydrate diet consumed during the 22-hour recovery period following prolonged intermittent high-intensity shuttle running had no greater effect on sprint performance or endurance capacity the following day than a LGI carbohydrate recovery diet.

Funding Source:

Other:

English Football Association

Reviewer Comments:

The discussion section outlines why their hypothesis may not have been proven correct: After running R2, Part A (75 minutes) their glycogen stores were both depleted to similar levels and thefore when starting Part B (run time to exhaustion), subjects in both trials had compensatory upregulation of fat oxidation. I think, therefore, it would have made more sense to compare trials betweens R2, Part A, just the initial 75 minutes, instead of Part B (run time to exhaustion).
I noted this as unclear in the statistical question in the quality checklist. For this reason and since there is very little description of the subjects, including health, inclusion criteria, recruitment and dropout, this article is considered neutral in quality.

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?		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?	Yes
	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)	???
	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?		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?	No
	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?	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?	No
	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?	???
	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?	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?	Yes
	10.2.	Was the study free from apparent conflict of interest?	Yes