EAL

NAP: Recovery (2007)

Citation:

Burke LM, Collier GR, Beasley SK, Davis PG, Fricker PA, Heeley P, Walder K, Hargreaves M. Effect of coingestion of fat and protein with carbohydrate feedings on muscle glycogen storage. J Appl Physiol. 1995; 78 (6): 2,187-2,192.

PubMed ID: 7665416

Study Design:

Randomized controlled trial

Class:

A - Click here for explanation of classification scheme.

Quality Rating:

NEUTRAL: See Quality Criteria Checklist below.

Research Purpose:

To determine the effects of coingestion of fat and protein, in amounts typical of an athlete's diet, on muscle glycogen storage after 24 hours of carbohydrate feedings.

Inclusion Criteria:

Well-trained cyclists or triathletes.

Exclusion Criteria:

None specifically mentioned.

Description of Study Protocol:

Recruitment: Methods not specified
Design: Randomized controlled trial
Intervention: Subjects randomly assigned to Control Diet, Added Fat and Protein Diet or Matched Energy Diet on three different testing days
Statistical Analysis: Data were compared using ANOVA for repeated measures. Specific differences between means were located using Newman-Keuls post-hoc test.

Data Collection Summary:

Timing of Measurements

Subjects undertook an exercise trial (two hours at 75% peak VO₂, followed by four 30-second sprints) on three occasions, one week apart
For 24 hours after each trial, subjects rested and consumed control diet, added fat and protein diet or matched energy diet provided as four meals at zero, four, eight and 21 hours of recovery
Blood samples were taken before and after meals, muscle biopsies taken before and 24 hours into recovery.

Dependent Variables

Muscle biopsy samples were taken from vastus lateralis and analyzed for glycogen content using an enzymatic fluorometric technique
Venous blood samples were obtained before the start of exercise, before each meal and 30, 60, 90 and 120 minutes after each meal
Plasma glucose was measured with an automatic analyzer by enzymatic method
Plasma insulin was measured with double-antibody radioimmunoassay
Plasma triglycerides were determined on an automatic analyzer
Serum FFAs were measured with a commercially available kit.

Independent Variables

Control Diet: High glycemic index CHO foods, CHO at seven grams per kg, approximately 77% CHO
Added Fat and Protein Diet: Seven grams per kg CHO, 1.6g per kg fat, 1.2g per kg protein, approximately 51% CHO, 31% fat, 18% protein
Matched Energy Diet: Seven grams per kg CHO + 4.8g per kg CHO as polycose to match additional energy in Added Fat and Protein Diet
Diet and activity records were kept over the previous 48 hours to standardize CHO intake and exercise and ensure that no strenuous activity had been undertaken for at least 36 hours prior to the trial.

Description of Actual Data Sample:

Initial N: Eight triathletes, gender not mentioned
Attrition (final N): Eight
Age: Mean, 23.1±2.0 years
Ethnicity: Not mentioned
Other relevant demographics: Mean weight, 74.0±3.4kg
Location: Australia.

Summary of Results:

Muscle Glycogen Concentrations

Diet	Zero Hours	24 Hours	Change
Control	34.6±9.7	120.2±9.6	85.7±2.7
Added Fat and Protein	23.5±6.5	104.0±3.8	80.5±8.2
Matched Energy	31.5±5.4	119.4±5.8	87.9±7.0

Other Findings

Total post-prandial incremental plasma glucose area was significantly reduced after the Added Fat and Protein Diet (P<0.05)
Serum FFA and plasma triglyceride responses were significantly elevated during the Added Fat and Protein Diet (P<0.05)
Despite the differences in plasma glucose areas at individual meals or in total, there were no differences in meal or total insulin areas between diets
There were no differences between trials in muscle glycogen storage over 24 hours (Control, 85.8±2.7mmol per kg wet weight; Added Fat and Protein, 80.5±8.2mmol per kg wet weight; Matched Energy, 87.9±7.0mmol per kg wet weight).

Author Conclusion:

In summary, the coingestion of moderate amounts of fat and protein does not appear to have a direct effect on glycogen storage during 24 hours of recovery from prolonged exercise, provided that CHO intake is adequate
Whether effects would be seen with lower CHO intakes and whether rates of muscle glycogen storage are influenced in the early stages (e.g., zero to six hours) of recovery remain unanswered. However, practical issues, which ensure that adequate CHO intake is achieved or other nutritional considerations may dictate the ideal intake of protein and fat in the athlete's post-exercise recovery diet.

Funding Source:

Government:

Applied Sports Research Program of the Australian Sports Commission, Australian Institute of Sport

Reviewer Comments:

Recruitment methods, inclusion and exclusion criteria and subjects were not well-described
Authors note that the seven-gram per kg CHO diet was chosen to be below guidelines for eight to 10g per kg CHO diet, but there were no differences between groups.

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?		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?	???
	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)	No
	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?		No
	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.)	No
	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?	Yes
	6.6.	Were extra or unplanned treatments described?	Yes
	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?		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)?	N/A
	8.5.	Were adequate adjustments made for effects of confounding factors that might have affected the outcomes (e.g., multivariate analyses)?	Yes
	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