1. Whey protein supplementation, resistance training, and
augmentation in muscle strength and lean mass among elderly
individuals: a meta-analysis
Melissa Anderson1,2
1
University of Massachusetts, Boston, Massachusetts. 2
Nutrition, Exercise, Physiology, and Sarcopenia Laboratory, Jean
Mayer USDA Human Nutrition Research Center on Aging, Tufts University, Boston, Massachusetts.
Abstract
Background: Protein ingestion post-resistance type exercise leads to muscle protein growth. Consequently, it
is generally accepted that protein supplementation is required to maximize the adaptive response of the
skeletal muscle to prolonged resistance training. However, there is inconsistency in the literature regarding
the proposed benefits of protein supplementation during prolonged resistance training in older populations.
Objective: To assess the efficacy of whey protein supplementation on muscle strength and mass when
included to resistance training program for older adults.
Design: A systematic review of interventional evidence through the use of a random effects meta-analysis
model. Data from the outcome variables fat mass, muscle mass, lower and upper extremity muscle strength
(1 repetition maximum/1-RM, grip strength), were collected from randomized control trials investigating the
effect of whey protein supplementation during resistance-type exercise training.
Results: Data were collected from 4 randomized control trials (RCTs) that included one hundred thirty-seven
subjects. Whey protein supplementation showed a positive effect for muscle mass compared with a placebo.
However, muscle strength and fat mass showed mixed results.
Conclusion: Whey protein supplementation increases muscle mass during prolonged resistance training in
older subjects. However, the effect of protein supplementation on muscle strength and fat mass was
insignificant, failing to verify the effects of protein supplementation on increasing and decreasing these two
variables.
Key words: Whey protein, older adults, muscle strength, muscle mass
Introduction
The present implications concerning
the health of our aging population illustrates
the need to shift attention to their functional
wellbeing. Moreover, the important role in the
loss of functional performance, and ability to
maintain a healthy active lifestyle, is the
progressive loss of muscle mass with aging, or
sarcopenia. Lean muscle mass generally
contributes to up to 50% of total body weight
in younger adults but declines with aging to
about 25% when reaching the age of 75-80
years (3). As a consequence, muscle mass loss
is typically offset by gains in fat mass.
Resistance training has been established as an
effective interventional strategy to prevent or
even reverse the age-related loss of skeletal
muscle mass and strength in the aging
population (6).

2. Substantial evidence suggests that
protein supplementation post resistance
training leads to an increase in muscle protein
development. Interestingly, studies suggest
that ingesting whey protein, a fraction of milk
protein, as a supplement results in even
greater increase in muscle synthesis of older
individuals than the supplementation of the
equivalent amount of other protein varieties
(1). However, the effects of whey protein
supplementation with resistance training on
muscle mass and strength have produced
varied results. This systematic review and
meta-analysis aimed to assess the effects of
whey protein supplementation on muscle
strength and lean mass augmentation post
resistance-type exercise in older adults.
Methods
Selection of Studies
This meta-analysis included randomized
controlled trials of whey protein
supplementation in adults aged 65 years and
older. Trials combining resistance-type
exercise training with whey protein ingestion
(through supplementation) with primary
outcome variables related to fat-free mass
(FFM), fat mass (FM), and/or 1-RM strength
were included in the original article
acquisition. Trials must have assessed two of
the three aforementioned variables to be
eligible for inclusion.
The University of Massachusetts
EBSCOhost databases, Pubmed, Journal of
Clinical Nutrition and Google Scholar were
searched for eligible trials. Reference lists
were also searched. Only studies published in
English-language were included. The
preliminary search yielded 35 relevant
citations. After articles were screened for
eligibility, 4 met the study consideration
criteria (Figure 1).
Study Eligibility and Data Extraction
All included research articles
contained a resistance training component
with at least one subject group receiving a
whey protein supplement. Additionally, each
research study needed to include a control
group that received a non-protein supplement.
Exclusion criteria were 1) if age-range less
than 65 years, 2) the whey protein was
combined with equal amounts of another
protein type 3) no relevant outcome variables
were measured that were predetermined for
this review.
Although all eligible studies in this
meta-analysis shared a common directive, the
studies examined slightly different
hypotheses. One study compared the effect of
supplementing whey protein with a placebo on
decreasing muscle fiber protein degradation
and bone resorption, another study compared
the effect of whey protein supplementation
and an isocaloric control on muscle mass and
muscle strength, while a third study compared
the effect of whey ingestion and caseinate on
muscle protein synthesis in elderly subjects.
The fourth study included investigated the
effects of a post-exercise leucine-enriched
whey protein supplement on lean mass and
muscle functions as compared to a regular
dairy product.
Results
Of the 35 studies identified by the
literature search, 4 fulfilled the inclusion
criteria and were included in the meta-analysis
(Figure 1 and Table 1). The characteristics and
quality of the eligible studies are included in
Table 1. The publication dates ranged from
2006 to 2013.
Characteristics of Studies
All studies were double-blinded
randomized controlled trials with subjects
assigned to a supplement group and control.
Data from 137 participants with an age range

3. between 65 and 85 years [mean (±SD): 70 ±
4] were included in the analysis (Table 1). Of
the 4 studies, 1 study was conducted in men
only while the other 3 where conducted in a
mixed population. Two studies were
conducted in participants diagnosed with
polymyalgia rheumatica, 1 study was
conducted in sedentary-mobility limited
individuals, whereas the other 2 studies were
conducted in elderly moderately active non-
obese participants.
Resistance Training Characteristics
Within 3 of the four studies, total
duration of resistance training program varied
from 12-24 wk, with a mean (±SD) of 18 ± 5
wk. The remaining study administered the
supplement and control immediately after
exercise. The number of exercise training
sessions per week ranged from 1 to 3, with a
mean of 3 ± 2 per week. With specific
reference to the type of resistance training
performed, 1 study performed upper extremity
exercises only, two performed upper (bench
press, chest press, and/or seated row) and
Figure 1. Whey protein Meta-analysis ‘PRISMA’ Flow Diagram.
Records screened
(n = 33)
Records identified through
EBSCOhost database
searching
(n = 6)
Additional records identified
through other sources
(n = 17)
Records after duplicates removed
(n = 33)
Records excluded
(n = 18) Missing full text
access, dissertation source,
protein source other than
whey
Full-text articles
assessed for
eligibility
(n = 15)
Full-text articles excluded,
with reasons
(n = 11) Excluded for age less
than 65 years, missing more
than 1 variable measure,
and/or protein supplement
other than more than 50%
whey
Studies included in
qualitative synthesis
(n = 4)
Studies included in
quantitative synthesis
(meta-analysis)
(n = 4)
Records identified through Pubmed
database searching
(n = 12)

4. Table 1. Baseline Characteristics of included Randomized Control Trials
Included
Study
Study
population
characteristics
Age (x¯ ±
SD);
Female (%)
Muscle
mass
index (x¯ ±
SD) kg/m2
Fat mass
index (x¯ ±
SD) kg/m2
Muscle
strength
(x¯ ± SD)
kg/m2
Protein
supplement
frequency
(dose); n
Control; n Duration of
intervention;
Methods assessed;
Bjorkman
et al.
2011
Diagnosed
with
polymyalgia
rheumatica
(PMR).
69.5;
89.4%
15.6
(1.80);
index
10.5
(3.45);
index
24.3 (9.1)
hand grip
strength;
upper
extremity
Whey/Casein
(7.0g/100g)
ratio (80:20);
24
Whey/Casein
(3.3g/100g) ratio
(20:80); 23
20 weeks Muscle mass, fat
mass, grip;
Dideriksen
et al.
2011.
Elderly
moderately
active non-
obese people
66 (1.5);
25%
53.75
(4.65);
mass
17.15
(1.2); mass
202.5 (26) 1
RM leg
press (kg) ;
lower
extremity
Whey
protein (5.6-
30.4g); 6
Water (300ml); 6 Immediately
after
exercise
Muscle mass, fat
mass, leg press;
Chalé et al.
2013
Mobility-
limited
77.6 (4.0);
58.7%
46.5 (4.5);
mass
25.7
(7.05);
mass
1239.5
(420.5) 1
RM double
leg press
Whey
(40g/d); 30
Isocaloric control; 29 24 weeks Muscle mass, muscle
strength, double leg
press;
Candow et
al.
2006
Elderly men 67.5; 0% 15.6
(4.95);
mass
169 (7) 1
RM leg
press;
lower
extremity
Whey (0.3g
protein/kg);
10
Maltodextrin/sucrose/
chocolate cocoa
(0.63g/kg); 10
12 weeks Muscle mass, muscle
strength, leg press;

5. lower extremity (leg curl, leg press, and/or
leg extension). Participants in each study
performed the training exercises between
70-80% of their one repetition maximum (1-
RM).
Supplementation Characteristics
The mean (±SD) amount of whey
protein provided by supplement was 25 ± 12
(range: 7-40 g). Two studies supplemented
with whey protein; 1 study supplemented
with a whey and casein protein (80:20 ratio
respectively); and 1 study supplemented
with a combination of whey protein
concentrate, whey protein isolate, calcium
caseinate, milk protein isolate, sodium
caseinate, and egg albumin. In the control
groups, 1 study used water, another used an
isocaloric control, one used a whey/casein
supplement (20:80 ratio respectively), and
another study used maltodextrin, sucrose,
chocolate cocoa blend mixed in cold water
(Table 1).
Effect on Fat Muscle Mass, and Strength
Compared with the control, protein
supplementation favored increases in muscle
mass with all studies showing a positive
effect (Figure 2). However, compared to the
control, fat mass increased in one study
whereas whey protein supplementation
favored fat mass loss in the remaining 2
studies analyzing this variable (Figure 3).
After analyzing muscle strength, there was
no comprehensible difference between
control and whey protein supplementation
(Figure 4).
-1 0 1 2 3
Study
Bjorkman 2011
Dideriksen 2011
Chalé 2013
Candow 2006
Favors Control Favors Whey
Figure 2. Forest plot of results of a meta-analysis showing effects of whey protein and control on
muscle mass.

6. Discussion
Compared with the control, whey
protein supplementation increased fat mass,
increased muscle strength and increased
muscle mass. These findings support the
general opinion that whey protein
supplementation can augment the amount of
muscle mass and strength when engaging in
resistance-type exercise. However, there is
much discrepancy in the literature results that
mirror the findings showed in this meta-
analysis. The conflicting data relating fat mass
change between control and supplementation
reiterates the lack of reliable data supporting
the positive effects of protein supplementation
on decreasing body fat. As for limitations, one
included the process of search and retrieval for
eligible articles. Another was the lack of
advanced statistical analysis to quantitative
illustrate the findings. Despite these
limitations, this meta-analysis provides a
general overview on the research thus far and
offers insight into the literature investigating
the proposed benefits of protein
supplementation to augment muscle mass and
-5 0 5 10
-15 -10 -5 0 5 10 15 20 25
Study
Bjorkman 2011
Dideriksen 2011
Chalé 2013
Favors Control Favors Whey
Figure 3. Forest plot of results of a meta-analysis showing effects of whey protein and control on fat
mass.
Study
Bjorkman 2011
Dideriksen 2011
Chalé 2013
Candow 2006
Favors Control Favors Whey
Figure 4. Forest plot of results of a meta-analysis showing effects of whey protein and control on muscle
strength.

7. strength during resistance-type exercise
training in older adults.
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This document is property of the Jean Mayer USDA Human Nutrition Research Center on Aging; Nutrition, Exercise, Physiology & Sarcopenia (NEPS)