NAP: Recovery (2014)
Pritchett, K, Bishop P, Pritchett R, Green M, Katica C. Acute effects of chocolate milk and a commercial recovery beverage on postexercise recovery indices and endurance cycling performance. Appl Physiol Nutr Metab. 2009; 34: 1,017-1,022.

To examine the effects of post-exercise consumption of a CHO replacement beverage (CRB) vs. chocolate milk (CHOC) on indices on muscle damage, CK and muscle soreness, as well as subsequent time to exhaustion.
- Cyclists and triathletes
- Minimum of two years' involvement in endurance sports
- Minimum of six training hours per week
- 19 to 49 years old.
- Younger than 19 years or older than 40 years of age
- Cyclist or triathlete with less than two years of involvement in endurance sports and less than six hours of training per week.
- Recruitment: Not described
- Design: Randomized crossover trial
- Blinding used: Subjects were blinded to the beverage.
Intervention
- Low fat chocolate milk (CHOC) vs. CHO replacement beverage (CRB) given immediately after the first exercise session and two hours into the recovery period
- The same total amount of CHO was given (1.0g per kg-1 per hour-1) and the beverages were isocaloric (2,488.0±557.9kcal vs. 2,319.6±663.5kcal for CHO vs. CRB, respectively)
- Water, but no other food or beverage were allowed during the recovery period.
Statistical Analysis
- Data as compared using a two-factor (treatment x time) repeated-measures analysis of variance (ANOVA)
- A Tukey's post-hoc test was applied in the case of a significant F-ratio to locate the differences with the ANOVA
- One-way ANOVA for repeated measures was used to compare markers of muscle damage (CK) muscle soreness and performance between trials
- Greenhouse-Geisser corrections were conducted for unequal variance data.
Timing of Measurements
Before and 15 hours to 18 hours after counter-balanced exercise on two occasions, separated by one week.
Dependent Variables
- Creatine kinase: Capillary blood analyzed on a spectrometer
- Time to exhaustion: On a cycle ergometer at 85% VO2 max until pedal cadence was slower than 60rpm-1 or the participant could no longer continue
- Muscle soreness: 10-cm visual analog scale with "no pain at all" at the left end and "unbearable pain" at the right end.
Independent Variables
Low-fat chocolate milk (CHOC) and a CHO replacement drink (CRB).
Control Variables
- A high-intensity workout (five minutes cycling at 60% VO2max warm-up, followed by three 10-second "all out" bicycle Wingate sprints, interspersed with 50-second active recoveries, repeated a total of six times) followed 15 to 18 hours later after recovery with a five-minute warm-up on a bicycle ergometer and then cycled at a pre-determined workload to elicit approximately 85% VO2max until exhaustion
- No coffee or alcohol or exercise for a minimum of 24 hours before testing
- Dietary intake was to be the same between the two trials as before the study (documented by a food frequency questionnaire and three-day food diary, respectively).
- Initial N: 10
- Attrition (final N): 10
- Age: 27.1±7.9 years
- Ethnicity: Not described
- Other relevant demographics: 55.2±7.2ml per kg-1 VO2max and 367.5±38.7W peak watts
- Anthropometrics: 176.5±3.6cm in height; 72.1±6.7kg body weight; 9.2±6.7% body fat
- Location: USA.
Findings
- The beverages were identical in CHO and similar in protein and kcals
- The significant difference in fat content (P<0.001) was not enough to significantly affect the difference in overall calorie content between the beverages
- There ware no significant differences in macronutrient intake between the two trials
- Sleep patterns were similar between the two trials
- All of the subjects preferred the taste and consistency of CHOC
- There was no significant difference (P=0.91) between trials for cycling time to exhaustion
- There was no significant difference (P=0.29) for the PRE CK level (CKpre) between the two trials
- A repeated-measures ANOVA revealed a significant (P<0.05) interaction (treatment x time) for change in CKpre to the POST CK level (CKpost)
- A significantly higher (P<0.05) was observed for the CRB trial, however there was no significant difference (P=0.35) for CKpost between the two trials.
- No interaction (treatment x time) for muscle soreness was observed
- There were no significant difference for PRE muscle soreness (P=0.98) and POST muscle soreness (P=0.48) between the two trials
- Subjective measures of muscle soreness decreased significantly (P<0.01) from PRE to POST.
There is no difference between CHOC and this CRB as potential recovery aids for cyclists between intense workouts.
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? | Yes | |
2. | Was the selection of study subjects/patients free from bias? | Yes | |
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? | Yes | |
2.2. | Were criteria applied equally to all study groups? | Yes | |
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? | Yes | |
3. | Were study groups comparable? | Yes | |
3.1. | Was the method of assigning subjects/patients to groups described and unbiased? (Method of randomization identified if RCT) | Yes | |
3.2. | Were distribution of disease status, prognostic factors, and other factors (e.g., demographics) similar across study groups at baseline? | Yes | |
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? | N/A | |
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%.) | N/A | |
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.) | N/A | |
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? | N/A | |
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? | N/A | |
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)? | 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 | |