NAP: Recovery (2014)


Hoffman J, Ratamess N, Tranchina C, Rashti S, Kang J, Faigenbaum A. Effect of a proprietary protein supplement on revcovery indices following resistance exercise in strength/power athletes. Amino Acids, 2010; 38: 771-778.

Study Design:
Randomized Controlled Trial
A - Click here for explanation of classification scheme.
Quality Rating:
Positive POSITIVE: See Quality Criteria Checklist below.
Research Purpose:

To examine the efficacy of pre- and post-exercise whey protein ingestion on recovery from an acute resistance exercise session.

Inclusion Criteria:
  • Male
  • Football team member or power lifting competitor
  • Three or more years experience resistance training.
Exclusion Criteria:
  • Female
  • Use of nutritional supplements within six weeks of study onset
  • Use of anabolic steroid or agent within year prior to study onset.
Description of Study Protocol:
  • Recruitment: Not discussed; participants were volunteers from the university
  • Design: Randomized controlled trial
  • Blinding used: Double-blind.


  • Participants consumed liquid protein supplement or placebo 10 minutes prior to and 15 minutes after strength training exercise
  • Proprietary protein supplement shake (enzymatically hydrolyzed collagen protein isolate, whey protein isolate, casein protein isolate plus 250mg BCAAs): 42g protein, two grams CHO and zero grams of fat
  • Placebo contained maltodextrin in water: 14.9g CHO, zero grams of protein and zero grams of fat.

Statistical Analysis

  • P≤0.05
  • ANOVA was used to analyze statistical evaluation of performance, hormonal and biochemical changes
  • In the event of a significant F-ratio, LSD post-hoc tests were used for the pairwise comparisons
  • Unpaired T-tests were were used to analyze dietary records, plasma volume shifts, changes in performance comparisons and training volume data.
Data Collection Summary:

Timing of Measurements

Subjects were in lab for four consecutive days.

Dependent Variables

  • Soreness: Measured prior to consumption of supplement or placebo
  • Serum testosterone: Baseline (prior to exercise), immediately following exercise (IP) and 15 minutes post-exercise (15P)
  • Serum cortisol: Baseline (prior to exercise), immediately following exercise (IP) and 15 minutes post-exercise (15P)
  • Serum creatine kinase: Baseline (prior to exercise), immediately following exercise (IP) and 15 minutes post-exercise (15P)
  • Plasma volume
  • Lower body power during squat (T2, 3, 4).

Independent Variables

Proprietary protein supplement vs. placebo.

Control Variables

  • Subjects matched for strength before being randomized to treatment groups
  • three-day dietary recalls completed the week prior to testing
  • All subjects performed the same strength training routine.
Description of Actual Data Sample:
  • Initial N: 15 males
  • Attrition: 15
  • Age
    • SUP: 19.5±1.5 years
    • PL: 20.0±1.1 years.
  • Ethnicity: Not discussed.

Other Relevant Demographics (Anthropometrics)

  • Height
    • SUP: 185.4±3.9cm
    • PL: 176.7±8.5cm.
  • Body mass
    • SUP: 96.4±11.9kg
    • PL: 85.8±12.0kg.


New Jersey, USA.

Summary of Results:

Key Findings

Group T2 T3 T4
Repetitions performed SUP 33.3±6.0 30.0±7.2* 31.0±7.6*
PL 33.8±7.4 23.0±7.9 22.0±8.5
Average peak power (W) SUP 980±292 954±344 938±344
PL 962±272 836±192 827±265
Average mean power (W) SUP 607±124 560±153 567±148
PL 596±144 481±136 519±133
  • The Supplement Group was able to perform significantly greater number of repetitions at both T3 and T4 than the Placebo Group
  • Average peak power and average mean power were not significantly different at any time.

Other Findings

  • Dietary recalls showed no difference between the groups in energy intake, PRO, CHO or fat intake
  • No difference was seen in the number of repetitions performed in the squat exercise during T2 between SUP and PL
  • Lower body muscle soreness was not significantly different between SUP and PL at both T3 and T4
  • No significant group or time effects were seen in changes in testosterone concentrations
  • Significant elevations in cortisol concentrations from baseline were seen during T2 at both IP and 15P for both SUP and PL, but no between-group differences were noted
  • Resting CK concentrations were significantly elevated at T3 and T4 compared to T2. No between-group differences were noted.
Author Conclusion:
  • The results of this study indicate that subjects consume a proprietary protein blend SUP before and after a resistance training session have a significantly greater improvement in exercise recovery 24 hours and 48 hours post-exercise than subjects ingesting a placebo
  • The changes in the pattern of the CK response between SUP and PL suggests that further research is warranted examining the effect that protein timing has on the muscle repair and rebuilding process.
Funding Source:
IDS Sports
Pharmaceutical/Dietary Supplement Company:
Reviewer Comments:
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? 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")? Yes
4. Was method of handling withdrawals described? N/A
  4.1. Were follow-up methods described and the same for all groups? N/A
  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.) 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? Yes
  6.6. Were extra or unplanned treatments described? No
  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? No
  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)? Yes
  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? No
  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