Study analysis · Nutrients · 2019
Protein shakes after workouts may not build muscle in older adults recovering from hospital—but the exercise itself might be the real hero.
In a small trial, older adults who did 12 weeks of strength training got better at daily physical tasks, but adding a whey-and-leucine protein drink after each session gave no extra benefit over a placebo.
Overview
What the study found
The study in plain English — the bottom line, every takeaway we extracted, and what to do with them.
In simple terms
This is a randomized trial, which is like flipping a coin to put people into two groups, so it's one of the best ways to test if a supplement works. But the study was small and didn't have a group that skipped exercise, so we can't be sure the exercise caused the improvements, and we can't say for sure the protein didn't help because there were too few people to detect small effects.
What’s the bottom line?
Older adults who had been in the hospital did 12 weeks of supervised strength training. Half got a protein drink after workouts; half got a placebo drink. Both groups got better at physical tasks, but the protein drink did not make them better than the placebo.
How strong is this study?
The study did some things right: it randomly assigned people and had a placebo, and the participants didn't know which supplement they got. But only 28 people finished, many dropped out, and the people measuring the results knew who got what, so the findings are less trustworthy—especially the conclusion that the protein supplement had no extra benefit.
40 / 100
- COI disclosure+40/40
- Data availabilitydata not shared
- Code availabilitycode not shared
71 / 100
- Randomization+20/20
- Blinding+9/15
- Control group+15/15
- Sample size (n=28)+2.6/20
- Follow-up+10/10
100 / 100
46 / 100
- P-values+15/15
- Effect sizeno effect size reported
- Confidence intervalsno confidence intervals
- Pre-registration+15/15
Each component is scored out of 100 and then capped by the study design — a case series cannot reach the ceiling a randomised trial can, however well it is reported.
Where it sits
RCT reviewsReviews of RCTs (Meta-analyses)
Max 100Randomized TrialsRandomized Trials
Max 90Reviews of Cohort StudiesReviews of Cohort Studies
Max 85Cohort StudiesCohort Studies
Max 72Reviews of Case-Control StudiesReviews of Case-Control Studies
Max 63Case-Control StudiesCase-Control Studies
Max 58Cross-Sectional & Case SeriesCross-Sectional & Case Series
Max 50Expert OpinionExpert Opinion
Max 564 / 100
Probability of being correct
Participants are randomly assigned to treatment or control groups, minimizing bias. The gold standard for testing whether an intervention causes an effect.
This design can establish causation. While randomization allows causal inference in principle, this study has important limitations: small sample (28 completers, underpowered), high dropout (13/41) with per-protocol analysis, single-blind (outcome assessors not blinded), no non-exercise control group for resistance training effects, and no control for daily protein/energy intake. Therefore, causal claims are weak, especially for negative findings.
COI Unknown
Could not determine conflict of interest status
No conflict of interest or funding statement was provided. The study used commercial whey protein and leucine supplements, and a company prepared the supplements, but author relationships and funding sources are not disclosed.
The text does not include a COI or funding section. Industry involvement includes use of Davisco whey protein isolate and Nutricia leucine, and supplement preparation by Laboratorium Sanitatis SL (Tecnalia Research and Innovation). Author affiliations and funding sources are not provided, so COI severity cannot be determined.
Key takeaways
- 01
12 weeks of strength training (2 times/week) improved physical function in both groups (p<0.01).
- 02
Adding a protein supplement (20 g whey + 3 g leucine) did not give extra improvement compared with placebo (p>0.05).
- 03
Muscle mass did not increase in either group.
- 04
Handgrip strength did not improve.
- 05
No relative or absolute effect sizes were reported—only p-values.
- 06
The study did not report absolute or relative effect sizes, so we cannot say how many extra people benefited or how large the functional improvement was.
- 07
The study was very small (28 completers), so the main practical message is uncertain: exercise likely helps function, but this trial could not show an extra benefit from protein supplementation.
Surprising findings
- No extra benefit from post-exercise protein supplementationThe study gave 20 g whey protein isolate plus 3 g leucine immediately after each session—a protocol designed to maximize the 'leucine trigger' for muscle protein synthesis—yet it performed no better than an energy-matched placebo.
- Muscle mass did not increase with training plus proteinResistance training and protein are both widely promoted for muscle growth in older adults, but DXA showed no significant muscle mass improvement in either group after 12 weeks.
- Placebo group's nutrition score improved from near-malnutrition to normalThe placebo group started with an average MNA of 23.1—just above the malnutrition-risk threshold—and ended at 25.3, achieving normal status, even though they received no protein supplement.
- Handgrip strength did not improve despite other strength gainsHandgrip is commonly used as a simple proxy for overall strength, but it failed to improve even as other physical function tests improved significantly.
Practical takeaways
If you're an older adult recovering from hospitalization, ask about a supervised resistance training program—2 sessions per week for 12 weeks improved physical function in this trial.
The study was small, single-blind, and had high dropout; findings are suggestive but not definitive.
medium confidenceDon't rely on a post-workout protein shake alone to build muscle; focus on overall daily protein and energy intake.
Daily protein and energy intake were not controlled in this study, so we can't rule out that total intake mattered more than timing.
low-to-medium confidenceTrack functional improvements like chair stands, walking speed, and balance—not just muscle mass or grip strength.
DXA cannot detect small muscle mass changes, and handgrip may not reflect whole-body strength changes.
medium confidenceExpect strength and function gains before measurable muscle size gains, especially in very old adults.
12 weeks may be too short to see muscle mass changes, and the study was underpowered for that outcome.
medium confidenceWhy this study matters
Exercise alone improved physical function
Both protein and placebo groups improved on physical function tests after 12 weeks of supervised resistance training (2 sessions/week), with within-group improvements significant at p<0.01. There were no significant between-group differences (p>0.05). No relative or absolute effect sizes were reported—only p-values.
This shows that even a relatively low-frequency, supervised strength program can help post-hospitalized seniors function better in daily life.
Protein supplement didn't move the needle
A supplement of 20 g whey protein isolate plus 3 g leucine after each training session did not produce extra gains in strength, physical function, or muscle mass compared with an energy-matched placebo (p>0.05).
This challenges the widespread marketing message that older adults need a post-workout protein shake to build muscle and recover.
Muscle mass didn't increase in 12 weeks
DXA scans showed no significant muscle mass improvement in either group after 12 weeks (p>0.05). DXA cannot detect changes smaller than about 1 kg, and the study was underpowered: 28 completers instead of the planned 35 per group.
Strength and physical function can improve even when measurable muscle growth doesn't show up on scans—an important distinction for anyone tracking progress.
Handgrip strength failed to improve
Despite improvements in lower and upper body strength tests, handgrip strength did not improve in either group. The authors suggest handgrip may not be a clinically relevant or valid measure of muscle function changes after resistance training in this population.
Grip strength is often used as a quick proxy for overall strength and health, but this study suggests it may not tell the whole story.
Nutrition status improved in both groups
MNA scores improved significantly within both groups (p<0.05). The placebo group went from an average of 23.1 (borderline risk of malnutrition) to 25.3 (normal nutritional status) after the training program.
Exercise may indirectly improve nutritional status, perhaps by increasing appetite, routine, or overall well-being—even without a protein supplement.
Want the whole report?
Detailed mode opens the full scientific breakdown — every score component, the methodology, conflicts of interest, the evidence analysis behind each claim, and the raw study data.
Overview
What the study found
The study in plain English — the bottom line, every takeaway we extracted, and what to do with them.
Not medical advice. For informational purposes only. Always consult a healthcare professional. Terms
Older adults who had been in the hospital did 12 weeks of supervised strength training. Half got a protein drink after workouts; half got a placebo drink. Both groups got better at physical tasks, but the protein drink did not make them better than the placebo.
Research results
12 weeks of strength training (2 times/week) improved physical function in both groups (p<0.01). Adding a protein supplement (20 g whey + 3 g leucine) did not give extra improvement compared with placebo (p>0.05). Muscle mass did not increase in either group. Handgrip strength did not improve. No relative or absolute effect sizes were reported—only p-values.
What this means - more context
The study did not report absolute or relative effect sizes, so we cannot say how many extra people benefited or how large the functional improvement was. The study was very small (28 completers), so the main practical message is uncertain: exercise likely helps function, but this trial could not show an extra benefit from protein supplementation.
To examine whether leucine-enriched whey protein supplementation after resistance training improves muscle mass, strength, and physical function in post-hospitalized older adults.
In this single-blind RCT, both protein and placebo groups showed within-group improvements in physical function after 12 weeks of supervised resistance training (p<0.01), but there were no significant between-group differences (p>0.05). Muscle mass did not improve in either group, and handgrip strength did not improve. Adding 20 g whey protein isolate + 3 g leucine after each session provided no additional benefit.
Methods Used
Post-hospitalized adults >70 years with sarcopenia criteria were randomized to protein supplement (20 g whey protein isolate + 3 g leucine) or energy-matched placebo after supervised resistance training (2 sessions/week for 12 weeks). Outcomes assessed at baseline and 12 weeks: physical function (Senior Fitness Test, SPPB, handgrip), body composition by DXA, MNA, and serum markers. 41 randomized; 28 completed.
Main Finding
12 weeks of resistance training improved physical function in both groups (p<0.01), but leucine-enriched whey protein supplementation did not provide additional benefits over placebo (p>0.05). No significant muscle mass improvement occurred in either group (p>0.05). No relative or absolute effect sizes were reported; results are based on p-values.
Confidence Level
Low to moderate. Small sample (28 completers vs planned 35/group), single-blind design, high dropout (13/41), per-protocol analysis, uncontrolled protein/energy intake, short duration, and DXA cannot detect changes <1 kg. Findings are suggestive but underpowered.
Study Flags
Red Flags
- •Small sample size (28 completers; underpowered for muscle mass)
- •Single-blind design and high dropout rate (13/41 dropped out)
- •No control of daily protein/energy intake and DXA cannot detect changes <1 kg
Surprising Findings
No extra benefit from post-exercise protein supplementation
The study gave 20 g whey protein isolate plus 3 g leucine immediately after each session—a protocol designed to maximize the 'leucine trigger' for muscle protein synthesis—yet it performed no better than an energy-matched placebo.
Practical Takeaways
If you're an older adult recovering from hospitalization, ask about a supervised resistance training program—2 sessions per week for 12 weeks improved physical function in this trial.
RCT reviewsReviews of RCTs (Meta-analyses)
Max 100Randomized TrialsRandomized Trials
Max 90Reviews of Cohort StudiesReviews of Cohort Studies
Max 85Cohort StudiesCohort Studies
Max 72Reviews of Case-Control StudiesReviews of Case-Control Studies
Max 63Case-Control StudiesCase-Control Studies
Max 58Cross-Sectional & Case SeriesCross-Sectional & Case Series
Max 50Expert OpinionExpert Opinion
Max 564 / 100
Probability of being correct
Participants are randomly assigned to treatment or control groups, minimizing bias. The gold standard for testing whether an intervention causes an effect.
Human RCT
Subject
Moderate probability
on the GRADE evidence scale
This is a randomized trial, which is like flipping a coin to put people into two groups, so it's one of the best ways to test if a supplement works. But the study was small and didn't have a group that skipped exercise, so we can't be sure the exercise caused the improvements, and we can't say for sure the protein didn't help because there were too few people to detect small effects.
Strengths
- Randomized, placebo-controlled design.
- Participants blinded to supplement allocation.
- Supervised resistance training program with personalized loads.
Weaknesses
- Small sample size (28 completers; planned 70).
- High dropout rate (13/41 randomized dropped out).
- Per-protocol analysis rather than intention-to-treat.
Methodology
Evidence Keywords
Statistical Reporting
Not medical advice. For informational purposes only. Always consult a healthcare professional. Terms
Older adults who had been in the hospital did 12 weeks of supervised strength training. Half got a protein drink after workouts; half got a placebo drink. Both groups got better at physical tasks, but the protein drink did not make them better than the placebo.
Research results
12 weeks of strength training (2 times/week) improved physical function in both groups (p<0.01). Adding a protein supplement (20 g whey + 3 g leucine) did not give extra improvement compared with placebo (p>0.05). Muscle mass did not increase in either group. Handgrip strength did not improve. No relative or absolute effect sizes were reported—only p-values.
What this means - more context
The study did not report absolute or relative effect sizes, so we cannot say how many extra people benefited or how large the functional improvement was. The study was very small (28 completers), so the main practical message is uncertain: exercise likely helps function, but this trial could not show an extra benefit from protein supplementation.
To examine whether leucine-enriched whey protein supplementation after resistance training improves muscle mass, strength, and physical function in post-hospitalized older adults.
In this single-blind RCT, both protein and placebo groups showed within-group improvements in physical function after 12 weeks of supervised resistance training (p<0.01), but there were no significant between-group differences (p>0.05). Muscle mass did not improve in either group, and handgrip strength did not improve. Adding 20 g whey protein isolate + 3 g leucine after each session provided no additional benefit.
Methods Used
Post-hospitalized adults >70 years with sarcopenia criteria were randomized to protein supplement (20 g whey protein isolate + 3 g leucine) or energy-matched placebo after supervised resistance training (2 sessions/week for 12 weeks). Outcomes assessed at baseline and 12 weeks: physical function (Senior Fitness Test, SPPB, handgrip), body composition by DXA, MNA, and serum markers. 41 randomized; 28 completed.
Main Finding
12 weeks of resistance training improved physical function in both groups (p<0.01), but leucine-enriched whey protein supplementation did not provide additional benefits over placebo (p>0.05). No significant muscle mass improvement occurred in either group (p>0.05). No relative or absolute effect sizes were reported; results are based on p-values.
Confidence Level
Low to moderate. Small sample (28 completers vs planned 35/group), single-blind design, high dropout (13/41), per-protocol analysis, uncontrolled protein/energy intake, short duration, and DXA cannot detect changes <1 kg. Findings are suggestive but underpowered.
Study Flags
Red Flags
- •Small sample size (28 completers; underpowered for muscle mass)
- •Single-blind design and high dropout rate (13/41 dropped out)
- •No control of daily protein/energy intake and DXA cannot detect changes <1 kg
Surprising Findings
No extra benefit from post-exercise protein supplementation
The study gave 20 g whey protein isolate plus 3 g leucine immediately after each session—a protocol designed to maximize the 'leucine trigger' for muscle protein synthesis—yet it performed no better than an energy-matched placebo.
Practical Takeaways
If you're an older adult recovering from hospitalization, ask about a supervised resistance training program—2 sessions per week for 12 weeks improved physical function in this trial.
RCT reviewsReviews of RCTs (Meta-analyses)
Max 100Randomized TrialsRandomized Trials
Max 90Reviews of Cohort StudiesReviews of Cohort Studies
Max 85Cohort StudiesCohort Studies
Max 72Reviews of Case-Control StudiesReviews of Case-Control Studies
Max 63Case-Control StudiesCase-Control Studies
Max 58Cross-Sectional & Case SeriesCross-Sectional & Case Series
Max 50Expert OpinionExpert Opinion
Max 564 / 100
Probability of being correct
Participants are randomly assigned to treatment or control groups, minimizing bias. The gold standard for testing whether an intervention causes an effect.
Human RCT
Subject
Moderate probability
on the GRADE evidence scale
This is a randomized trial, which is like flipping a coin to put people into two groups, so it's one of the best ways to test if a supplement works. But the study was small and didn't have a group that skipped exercise, so we can't be sure the exercise caused the improvements, and we can't say for sure the protein didn't help because there were too few people to detect small effects.
Strengths
- Randomized, placebo-controlled design.
- Participants blinded to supplement allocation.
- Supervised resistance training program with personalized loads.
Weaknesses
- Small sample size (28 completers; planned 70).
- High dropout rate (13/41 randomized dropped out).
- Per-protocol analysis rather than intention-to-treat.
Methodology
Evidence Keywords
Statistical Reporting
Scoring
How strong is this study?
The study did some things right: it randomly assigned people and had a placebo, and the participants didn't know which supplement they got. But only 28 people finished, many dropped out, and the people measuring the results knew who got what, so the findings are less trustworthy—especially the conclusion that the protein supplement had no extra benefit.
40 / 100
- COI disclosure+40/40
- Data availabilitydata not shared
- Code availabilitycode not shared
71 / 100
- Randomization+20/20
- Blinding+9/15
- Control group+15/15
- Sample size (n=28)+2.6/20
- Follow-up+10/10
100 / 100
46 / 100
- P-values+15/15
- Effect sizeno effect size reported
- Confidence intervalsno confidence intervals
- Pre-registration+15/15
Each component is scored out of 100 and then capped by the study design — a case series cannot reach the ceiling a randomised trial can, however well it is reported.
Where it sits
RCT reviewsReviews of RCTs (Meta-analyses)
Max 100Randomized TrialsRandomized Trials
Max 90Reviews of Cohort StudiesReviews of Cohort Studies
Max 85Cohort StudiesCohort Studies
Max 72Reviews of Case-Control StudiesReviews of Case-Control Studies
Max 63Case-Control StudiesCase-Control Studies
Max 58Cross-Sectional & Case SeriesCross-Sectional & Case Series
Max 50Expert OpinionExpert Opinion
Max 564 / 100
Probability of being correct
Participants are randomly assigned to treatment or control groups, minimizing bias. The gold standard for testing whether an intervention causes an effect.
This design can establish causation. While randomization allows causal inference in principle, this study has important limitations: small sample (28 completers, underpowered), high dropout (13/41) with per-protocol analysis, single-blind (outcome assessors not blinded), no non-exercise control group for resistance training effects, and no control for daily protein/energy intake. Therefore, causal claims are weak, especially for negative findings.
COI Unknown
Could not determine conflict of interest status
No conflict of interest or funding statement was provided. The study used commercial whey protein and leucine supplements, and a company prepared the supplements, but author relationships and funding sources are not disclosed.
The text does not include a COI or funding section. Industry involvement includes use of Davisco whey protein isolate and Nutricia leucine, and supplement preparation by Laboratorium Sanitatis SL (Tecnalia Research and Innovation). Author affiliations and funding sources are not provided, so COI severity cannot be determined.
Standing
The people behind it
The researchers who wrote the study this analysis is built on.
Authored by
10 researchersIf this is your work, this is how we attribute it on Fit Body Science. María Amasene is listed as the lead author.