RELATION BETWEEN THE AMOUNT OF FAT FREE MASS AND
MUSCLE STRENGTH
Ingeborg M. Dekker & José Oudejans
Department of Nutrition and Dietetics, School of Sports and Nutrition, Hogeschool van
Amsterdam, University of Applied Science
Bachelor opleiding Voeding en Diëtetiek
2011106a, januari 2011
Hogeschool van Amsterdam
By Dekker I.M & Oudejans, J.
RELATION BETWEEN THE AMOUNT OF FAT FREE MASS AND MUSCLE STRENGTH
Ingeborg M. Dekker, José Oudejans
Auteurs
Inge Dekker
Korte Ruigeweg 28
1751 DE Schagerbrug
[email protected]
José Oudejans
Molendijk 8
1636 VK Schermerhorn
[email protected]
Afstudeerproject
2011106a
Opdrachtgever
P.J.M Weijs
Hogeschool van Amsterdam
Dr. Meurerlaan 8
1067 SM Amsterdam
Praktijkbegeleider
S.E. van der Plas
Docentbegeleider
Ir. A.M Verrijen
Copyright ©2011, Dekker, I.M, Oudejans, J
© Niets uit deze scriptie mag worden verveelvoudigd of openbaar gemaakt, in enige vorm of op enige wijze, hetzij
elektronisch, mechanisch, door fotokopieën of op enige manier, zonder voorafgaande toestemming van de auteurs.
By Dekker I.M & Oudejans, J.
By Dekker I.M & Oudejans, J.
VOORWOORD
Deze scriptie is geschreven in het kader van ons afstudeerproject van de bacheloropleiding Voeding
en Diëtetiek aan de Hogeschool van Amsterdam. In deze scriptie beschrijven wij de resultaten van de
baseline gegevens van de Welprex studie, een onderzoek naar de effecten van een hypocalorisch,
eiwitverrijkt dieet, in combinatie met krachttraining bij volwassenen met overgewicht of obesitas.
Wij hebben gekeken naar de relatie tussen de hoeveelheid vet vrije massa en spierkracht die de
deelnemers hadden. Daarnaast hebben wij gekeken of deze relatie verschillend is voor de jongere en
de oudere deelnemers van dit onderzoek, deelnemers met een hoge of lage body mass index (BMI)
en het verschil tussen mannen en vrouwen.
De Welprex studie is opgezet en uitgevoerd door andere studenten. Aanleiding voor het gebruiken
van de gegevens van dit onderzoek was de te late goedkeuring van de medisch ethische
toetsingscommissie van het VU Medisch Centrum voor het starten van ons eigen opgezette
onderzoek; De Muscle Preservation Study. Helaas konden wij hierdoor pas begin januari 2011
konden starten met dit onderzoek. Hierdoor konden wij de gegevens niet meer verwerken voor het
einde van onze afstudeerperiode. Daarom hebben wij onze scriptie die gericht was op de Muscle
Preservation Study aangepast op de resultaten van de Welprex studie.
Gedurende onze afstudeerperiode hebben wij steun gehad van diverse mensen, die wij hier graag
voor willen bedanken.
Allereerst willen wij onze docentbegeleidster Amely Verreijen erg bedanken. Dankzij jou hebben wij
deze opdracht met grote enthousiasme kunnen uitvoeren omdat je altijd enthousiast was, een
heldere toelichting gaf en ons hielp met vragen. Ook willen wij Stefanie de Boer en Merel Bron
bedanken. Met z’n vieren hebben wij de Muscle Preservation Study opgezet. Bedankt voor jullie
enthousiasme, gezelligheid en de goede samenwerking!
Verder willen wij onze praktijkbegeleidster Suzanne van der Plas, diëtiste van Vialente , bedanken
voor de begeleiding, de goede hulp bij het uitvoeren van de metingen, prettige samenwerking,
adviezen en tips.
Ten slotte bedanken we onze opdrachtgever Peter Weijs voor het helpen met het opzetten van de
Muscle Preservation Study en de tips tijdens het voedingslab overleg.
Amsterdam, januari 2011
Inge Dekker en José Oudejans
By Dekker I.M & Oudejans, J.
By Dekker I.M & Oudejans, J.
ABSTRACT
Background: The population in the Netherlands is aging and adults with an age of 18 and older
are getting more overweight and obesity. One of the characteristics of aging is a change in body
composition. Fat free mass (FFM) and muscle mass are decreasing and fat infiltration in the muscles
could lead to decreased muscle functioning and thereby muscle strength. This process of decreasing
muscle mass is named ‘sarcopenia’ and often leads to many problems like diminish physical
functioning when people are getting older. Therefore, it is important to analyze the relation between
FFM and muscle strength, for younger en older adults, adults with a low and high BMI and males and
females.
Aim: To determine the relation between the amount of FFM and muscle strength, and whether this
relation is different for younger (18 – 39 years) compared to older adults (40 – 76 years), whether
this relation differs for adults with a low BMI (BMI ≥ 30,6) or a high BMI (BMI < 30,6) and whether
this relation is different for gender.
Methods: Subjects were recruited in the surroundings of the research centre, by posting 5000
flyers. During a weight loss trail in a period of 9 weeks body composition and muscle strength were
measured. FFM was measured by the BodPod and muscle strength with an JAMAR® Hydraulic Hand
Dynamometer. Baseline data was used to analyze the relation between FFM and muscle strength.
The significance level was set at p < 0,05.
Results: Seventy one overweight adult males (n=17) and females (n=54) participated in the study.
The mean age of the study population was 40 years and the mean BMI was 31,6. The mean FFM for
males was 69,5 kg and 48,6 kg for females. The mean muscle strength was 47,0 kg for males and 28,9
kg for females. The results showed a significant relation between FFM and muscle strength (r =
0,793, p < 0,001). There was no significant interaction of age or BMI between FFM and muscle
strength (r = 0,793, p = 0,874 and r = 0,812, p = 0,539 respectively).
However, this study showed that there was an interaction of gender in the relation between FFM and
muscle strength for males and females. Gender also appeared to be an effect modifier (p = 0,115).
There was a significant relation between FFM and muscle strength for males (p = 0,002) and females
(p = 0,002). It is notable that for the male participants 1 kg more FFM means 0,998 kg more muscle
strength. For the females means 1 kg more FFM 0,429 kg more muscle strength, which is 57 percent
less strength per kg FFM than the males. The mean amount of FFM was 20,8 kg more in males, which
is a significant difference (p < 0,001). The differences in the amount of FFM between younger and
older participants was 7,3 percent for males and 2,5 percent for females. Males were stronger than
females(p <0,001), but within gender no significant differences were found in muscle strength in
younger and older participants (males p = 0,094 and females p = 0,648). Also the quality of the
muscles differs significantly in males and females (p = 0,026)
Conclusion: In conclusion, this study indicates that there is a significant relation between FFM and
muscle strength. This relation is not different in younger and older participants and in participants
with a low or high BMI. Gender gives an interaction in relation between FFM and muscle strength.
Key words: Muscle strength, overweight, fat free mass, BMI
By Dekker I.M & Oudejans, J.
By Dekker I.M & Oudejans, J.
CONTENT
1. Introduction....................................................................................................................................... 11
2. Methods ............................................................................................................................................ 15
2.1 Participants .................................................................................................................................. 15
2.1.1 Recruitment of participants ................................................................................................. 15
2.2 Study design and measurements ................................................................................................ 15
2.2.1 Fat free mass ........................................................................................................................ 15
2.2.2 Muscle strength .................................................................................................................... 16
2.2.3 Other characteristics ............................................................................................................ 16
2.3 Statistical analysis........................................................................................................................ 16
3. Results ............................................................................................................................................... 17
3.1 The amount of fat free mass in relation to muscle strength ...................................................... 17
3.2 Age in the relation between fat free mass and muscle strength ................................................ 19
3.3 BMI in the relation between fat free mass and muscle strength ............................................... 21
3.4 Gender in the relation between fat free mass and muscle strength .......................................... 22
4. Discussion .......................................................................................................................................... 25
4.1 The amount of fat free mass in relation to muscle strength ...................................................... 25
4.2 Age in the relation between fat free mass and muscle strength ................................................ 26
4.3 BMI in the relation between fat free mass and muscle strength ............................................... 27
4.4 Gender in the relation between fat free mass and muscle strength .......................................... 28
4.5 Strengths and limitations ............................................................................................................ 28
5. Conclusion and recommendations .................................................................................................... 31
6. References ......................................................................................................................................... 33
Appendix 1: Muscle Preservation Study................................................................................................ 37
By Dekker I.M & Oudejans, J.
1. INTRODUCTION
In the Netherlands the population is aging. In 2010 15,3 percent of the population is 65 years or
older.1 With aging, body composition changes: skeletal muscle mass and strength is decreasing and
fat mass is increasing. This loss of skeletal muscle mass and strength is called ‘sarcopenia’ and begins
in the fourth decade of life (30 – 39 years).2 For elderly, the reduction of muscle strength is
proportionally larger than the reduction of muscle mass and this is probably due to reduction of
muscle quality.3 Sarcopenia is related to several problems, such as frailty, problems with daily
functioning and loss of independence.4 Therefore sarcopenia can cause a decrease in the quality of
life.5
There are several reasons for the changes in body composition in the elderly. One of them is a
decline in activities of the insulin-like growth factor-1 (IGF-1) hormone and the decline in activities of
several anabolic hormones, like testosterone and hydroepiandosterone sulphate (DHEAS).
For both sexes there is an increased fall in circulation of IGF-1 during aging.6 Decreasing levels of
testosterone in the blood leads to smaller anabolic effects on muscles, especially for females.7
Decreasing circulating hormone concentrations of DHEAS is caused by a decline of adrenal secretion.
The decline of mentioned hormones leads to less anabolic effects on the muscles and therefore a
loss of muscle mass, muscle strength, fitness and wellbeing during the aging process and an increase
in fat mass, which all are processes during aging. 6 7 8
A third reason for the changes in body composition in elderly is the decrease in physical activity. Less
physical activity results in less muscle mass, greater fat infiltration into the muscles and lower muscle
strength and muscle function.7 14 All these factors give an increased risk of mobility loss in the elderly.
With regular activity it is possible that age related loss of muscle mass and raised fat infiltration in
the muscle can be reduced.15 Elderly who regularly exercise have a lower chance to develop frailty
than elderly who do not.16 Another good reason to do more exercise is that physical activity
stimulate the anabolic effect of protein intake on the muscle protein synthesis17
By Dekker I.M & Oudejans J.
Chapter: 1. Introduction
Another reason for changes in body composition can be an insufficient intake of protein. The
recommended dietary allowance (RDA) for protein is 0,8 g protein/kg body weight/day for adults.5
There is an association between protein intake and FFM: people with high amounts of protein intake
lost significantly less FFM than people who take lower amounts of protein.9 This association can be
explained by muscle protein synthesis which is stimulated through protein intake.5 Intake of protein
also inhibits the breakdown of proteins.10
Different studies give various results concerning muscle protein synthesis by elderly.5 11 12 The results
of these studies do not give a clear answer to the question whether elderly people have a higher
protein need, but a study from Wolfe et al. shows that 0,8 g protein/kg body weight/day may
underestimate protein needs in the elderly and recommends for this population amounts up to 1,5 g
protein/kg body weight/day.5
In the Netherlands elderly females aged 50 to 65 years, 65+ and 75+ years are consuming 1,08, 1,03
and 1,04 g protein/kg bodyweight/day respectively. Elderly males in the Netherlands aged 50 to 65
years, 65+ and 75+ years are consuming 1,18, 1,10 and 1,06 g protein/kg bodyweight/day
respectively.13 This intake is more than the RDA, but may be insufficient to optimize protein synthesis
and minimize protein breakdown according to Wolfe et al.5
11
Sarcopenia leads to less physical functioning in the elderly but physical activity can work against this
process. Elderly who engage in at least a moderate amount of physical activity similar to 400
kcal/day, have better physical functioning than persons who are less active. Participating in 20-30
minutes in a moderate intensity exercise on most days of the week is comparable to 400 kcal a day.
Elderly who participate in regular exercise activities have more benefits in activities of daily living
such as walking, standing up from a chair, light household work and more.18
Less physical activity may lead to a decline of muscle mass and therefore muscle strength. Several
studies have investigated this topic. Some studies indicate that there is a relation between muscle
mass and physical function in the elderly.19 For example a study of Reid, et al. indicates that there is a
strong relationship between total lean leg mass and leg strength. Total lean leg mass is a predictor of
the level of mobility disability.20 Some others indicate that there is a relation between quadriceps
muscle strength and different performances and that maximal quadriceps muscle power is a
predictor of lower extremity functional performance.19 21 Quadriceps muscle strength, for example, is
related to chair rise time and time to walk a distance of 6 meters.19
There are only a few studies that described the influence of the changes in muscle mass on changes
in muscle quality and muscle strength in the elderly. Results from earlier studies, for example
Goodpaster et al. show that the measured differences in muscle strength are not always related to
muscle mass. More muscle mass does not automatically provide more power. Changes in muscle
mass in the elderly may lead to more fat in de muscles, but it is not yet shown in which way this
influences muscle strength and muscle function. A higher BMI is related to more intermuscular thigh
adipose tissue and causes a decrease in muscle quality.22
In summary, some studies show that there is a direct or strong relation between decline in muscle
mass and a decrease in muscle strength by an increasing age. 20 22 There are other studies that argue
that there is no linear relation and that the muscle strength not only depends on muscle mass,4 but
also on muscle quality.22
Sarcopenic obesity gives more physical disabilities than sarcopenia or obesity alone. These physical
disabilities can cause a sedentary lifestyle, which may contribute to a loss of muscle mass and poor
muscle quality and leads to a decrease in metabolic rate during physical activity and in periods of
rest. This loss of muscle mass and muscle quality may cause a further sedentary lifestyle and thereby
the person ends up in a vicious circle.8 On the other hand sarcopenia leads to lower physical activity,
By Dekker I.M & Oudejans J.
Chapter: 1. Introduction
In the Netherlands 47,2 percent of the population is overweighted and 11,8 percent is obese, when
taking to account elderly people, 56,6 percent is overweight and 15,2 percent is obese.23 When
obese elderly people develop for example rheumatoid arthritis or malignancy, the lean body mass is
decreasing while fat mass preserves or increases. This phenomenon is called ‘sarcopenic obesity’.4
Accumulations of lipids within the muscles is higher with an increased age and is associated with
lower muscle quality in the elderly.22
BMI is associated with more muscle mass. An important characteristic of these muscles is that they
have another composition and contain more fat when compared with people with a lower BMI. This
fat infiltration leads to a lower muscle quality, which causes a decrease in muscle strength and
diminished functioning.22 24
12
decreased energy expenditure, fat gain and obesity,24 these changes in the body may coexist whitin
the same person.8
Sarcopenic obesity is a predictor for functional capacity and mortality and causes a decrease in daily
physical functioning, such as climbing stairs, going downstairs and walking.24 It is also related to a
higher risk of developing the metabolic syndrome.25
Females have more fat mass and a lower muscle strength than males,22 so sarcopenic obesity is
probably more prevalent among females,4 but further research is necessary.
Dieticians often use the FFM to determine the body composition. FFM is significantly related to
muscle mass.26 With aging the changes in FFM are also significantly related to the changes in muscle
strength.27 Gender also plays an important role in the relationship between the amount of FFM and
muscle strength. Because the differences among males and females, most studies split this relation
up for gender.28 Males have a higher muscle quality, produce more power and are stronger than
females.29 The differences in muscle strength between males and females could not only be
explained by different muscle size.22 These differences in gender are caused by qualitative and
quantitative changes in muscles.29
But the relation between FFM and muscle strength has not been studied extensively. For this reason
further research on FFM and the relation with muscle strength is important. Therefore the main
research question of this study is: What is the relation between the amount of fat free mass and
muscle strength?
This study also will be answering the following subquestions:
1) Is the relation between the amount of fat free mass and muscle strength different for
younger (18 – 39 years) and older adults (40 – 76 years)?
2) What is the influence of BMI in the relation between fat free mass and muscle strength?
3) What is the influence of gender in the relation between fat free mass and muscle strength?
Chapter: 1. Introduction
The hypothesis of the current intervention is that there is a significant relation between FFM and
muscle strength. The present study also expects to see differences in the relation between FFM and
muscle strength for age, BMI and gender.
By Dekker I.M & Oudejans J.
13
Chapter: 1. Introduction
By Dekker I.M & Oudejans J.
14
2. METHODS
Originally, baseline data of the Muscle Preservation Study (see appendix 1 for more details) would be
used to answer the research questions. Because the medical ethical committee did not gave
permission to start the Muscle Preservation Study on time, other data and research questions were
used. The data of a study named ‘the Welprex study’ were used to answer the research questions.
Methods of this study are described below.
2.1 Participants
The participants participated in a weight loss trail for 9 weeks, from february until may 2009. During
those 9 weeks, different diet interventions were compared. The study was conducted in the
nutritional assessment laboratory at the Hogeschool van Amsterdam.
Participants were included for participation if they had a BMI ≥ 25 and had an age of 18 years or
older. Participants were excluded if they had thyroid gland disability, diabetes with insulin as
medicine or if they had any existing medical conditions that require medication that would affect
primary or secondary outcomes of the study. Pregnant and lactating females were excluded from the
study. Also participants who used anti depression medication, oral steroids and have joint problems
were excluded.
2.1.1 Recruitment of participants
Participants were recruited in the surrounding area of the research location (Hogeschool van
Amsterdam, University of Applied Sciences, School of Sports and Nutrition, department of Nutrition
and Dietetics) by posting 5000 flyers.
2.2 Study design and measurements
Cross-sectional data analysis was performed using data of FFM and muscle strength and only
baseline data of the ‘Welprex study’ was used.
2.2.1 Fat free mass
Body fat percentage, fat mass and FFM was measured using air displacement plethysmography, the
BodPod (Life Measurement Inc, Concord, CA). Fat percentage was determined using the Siri
equation. Before measurements the BodPod was calibrated with a cylinder with a known volume,
twice a day. Before each participant took place in the BodPod, the investigators checked if the
participants met the criteria, described above.
By Dekker I.M & Oudejans J.
Chapter: 1. Introduction
The participants were not allowed to drink energy or caffeine containing drinks and eat anything at
least three to four hours before measurements, drink anything in the last hour before
measurements, eat and drink excessive the day before measurements, smoke or drink alcohol on the
day of measurements, sport or visit the sauna on the day of measurements or within 14 hours before
measurements and they are not allowed to take a shower one hour before measurements.
Before the measurements the participants are not allowed to be sweaty and they had to visit the
toilet. The participants also needed to wear tight clothing and they had to take off extra volume such
as glasses, jewellery, watches etc.
15
During one measurement, the Bodpod measures twice and takes the mean of the two
measurements. If the difference between the two measurements was more than 150 ml, another
measurement was necessary. The BodPod was a reliable and valid method for estimation of fat mass
and FFM.30
2.2.2 Muscle strength
Muscle strength was measured with a JAMAR® Hydraulic Hand Dynamometer.The instrument has an
adjustable handle for various size hands and a peak-hold needle that automatically records the
highest force exerted. The participants needed to squeeze the instrument as hard as possible for 3
seconds and were asked to do the test three times with each hand. The mean of the scores from the
left hand and the right hand were used.31
2.2.3 Other characteristics
General characteristics like age and gender were also registered during the baseline measurements.
Length and weight were measured to determine the BMI. Weight was measured with the BodPod.
2.3 Statistical analysis
Chapter: 1. Introduction
Data were analyzed using SPSS software (PASW statistics version 18.0). The relation between FFM
and muscle strength was analyzed with linear regression analyses. The significance level was set at p
< 0,05.
There was tested for confounding by age, gender and BMI and the variable was defined as a
confounder if the β changed > 10 percent. There was also tested for effect modification by age,
gender and BMI and a p-value of 0,15 was used to define whether there was an interaction.
By Dekker I.M & Oudejans J.
16
3. RESULTS
In total 71 participants were included. The mean age of the study population was 40 years, 24
percent of the participants were males and the mean BMI was 31,6. Other characteristics of the
participants are presented in table 1.
Table 1: Characteristics research populationa
Caracteristic
Male (n = 17)
Age (y)
42 ± 15,6
Height (cm)
178 ± 8*
Weight (kg)
102,3 ± 13,5*
b
2
BMI (kg/m )
32,3 ± 4,4
Fat free mass (kg)
69,5 ± 6,4*
Fat mass (kg)
32,8 ± 12,2
Fat mass (%)
31,3 ± 8,3*
Muscle strength right hand (kg)
50,1 ± 10,9*
Muscle strength left hand (kg)
44,0 ± 8,6*
Average muscle strength (kg)
47,0 ± 9,2*
Average muscle strength(kg)/kg FFM
0,67 ± 0,13*
a
Data were displayed as means, ± standard deviation
b
Body Mass Index
* Males differs significantly from females (p < 0,05)
Female (n = 54)
Total (n = 71)
40 ± 12,7
165 ± 7
85,3 ± 15,9
31,4 ± 4,6
48,6 ± 6,2
36,7 ± 11,3
42,3 ± 5,8
29,6 ±6,6
28,3 ±7,3
28,9 ± 6,6
0,60 ± 0,10
40 ± 13,3
168 ± 9
89,4 ± 16,9
31,6 ± 4,5
53,6 ± 10,9
35,8 ± 11,5
39,7 ± 8,0
34,5 ± 11,7
32,0 ± 10,2
33,3 ± 10,6
0,62 ± 0,12
3.1 The amount of fat free mass in relation to muscle strength
Chapter: 3. Results
The study population was divided into two groups with different amounts of FFM. The group with a
high FFM were the participants who had ≥ 50,6 kg FFM and the group with a low FFM were the
participants who had < 50,6 kg FFM. This cut-off point was based on the median for the total group.
Based on this cut-off point all the males were defied in the high FFM group.
By Dekker I.M & Oudejans J.
17
The data showed a significant relation between FFM and muscle strength (r = 0,793, p < 0,001).
Figure 1 shows the relation between FFM and muscle strength, split up for the high FFM group and
the low FFM group.
Figure 1: Relation between FFM and muscle strength, split up for high FFM and low FFM
The difference in muscle strength between the high FFM group and the low FFM group was 11,4 kg.
These amounts were significantly different (p < 0,001). The mean muscle strength for the high FFM
group was 38,9 kg ± 10,9, the mean muscle strength for the low FFM group was 27,5 kg ± 6,6. These
differences are shown in figure 2.
Chapter: 3. Results
Figure 2: Differences in handgrip between the high FFM group and the low FFM group
* Significant difference between low FFM group and high FFM group
Whiskers represents 1 standard deviation
By Dekker I.M & Oudejans J.
18
3.2 Age in the relation between fat free mass and muscle strength
There was no significant interaction of age in the relation between FFM and muscle strength (r =
0,793, p = 0,874). The relation between FFM and muscle strength, split up for younger and older
participants, is presented in figure 3.
Chapter: 3. Results
Figure 3: Relation between FFM and muscle strength split up for young and old participants
a
Participants aged from 18 to 39 years old
b
Participants aged from 40 to 76 years old
These groups were divided on basis of the median.
By Dekker I.M & Oudejans J.
19
The relation between FFM and muscle strength, split up for gender and age, is showed in figure 4.
Figure 4: Relation between FFM and muscle strength, split up for gender and age
Figure 5: Differences in FFM between males and females, split up for the younger and older
participants
Whisker presents 1 standard deviation
By Dekker I.M & Oudejans J.
Chapter: 3. Results
The mean FFM for younger and older males was 72,0 kg ± 7,3 and 66,7 kg ± 4,1 respectively. For the
females those means were 49,2 kg ± 6,1 for the younger and 48,0 kg ± 6,4 for the older participants.
These differences were not significantly different between the older and younger male and female
participants (p = 0,092 and p = 0,477 respectively). These differences are presented in figure 5.
20
3.3 BMI in the relation between fat free mass and muscle strength
There was no significant interaction of BMI in the relation between FFM and muscle strength (r =
0,812, p = 0,539). The relation between FFM and muscle strength, split up for gender and
participants with a high BMI or low BMI are showed in figure 6.
Figure 6: Relation between FFM and muscle strength, split up for gender and BMI
Figure 7: Differences in muscle strength between males and females, split up for the low BMI group
and the high BMI group
Whiskers represents 1 standard deviation
By Dekker I.M & Oudejans J.
Chapter: 3. Results
The mean muscle strength for males was 68,7 kg ± 6,8 in the high BMI group and 71,0 kg ± 5,9 in the
low BMI group. For females the mean FFM was in the high BMI group and the low BMI group
respectively 52,1 kg ± 5,9 and 45,0 kg ± 4,0. Those differences were not significant for males (p =
0,114) and females (p = 0,397) and are shown in figure 7.
21
3.4 Gender in the relation between fat free mass and muscle strength
The data showed that there was a difference in the relation between FFM and muscle strength in
males and females (p = 0,049). The relation between FFM and muscle strength is adjusted for gender,
because this variable was an effect modifier for this relation. Since gender appear to be an effect
modifier in the relation between FFM and muscle strength (p = 0,115), the presented models in table
2 displayed the relationship between FFM and muscle strength for males and females individually.
Table 2: Regression coefficients for the relation between FFM and muscle strengtha
β(SE)
P
All participants
Model
0,769 (0,071)
< 0,001
Male
Model
0,998 (0,264)
0,002
Female
Model
0,429 (0,134)
0,002
It is notable that for the male participants 1 kg more FFM means 0,998 kg more muscle strength. For
the females 1 kg more FFM means 0,429 kg more muscle strength, which is 57 percent less strength
per kg FFM than the males.
There was a significant relation between FFM and muscle strength for males(p = 0,002) and females
(p = 0,002) . Those relationships are presented in figure 8.
Figure 8: Relation between FFM and muscle strength, split up for males and females
The quality of the muscles significantly differs for males and females (p = 0,026)
The data showed that males were stronger than females (p < 0,001). Within gender there are no
significant differences in muscle strength between the younger and the older group (males p = 0,094,
By Dekker I.M & Oudejans J.
Chapter: 3. Results
The male participants in this study were having a significantly higher FFM than the female
participants (p < 0,001). The mean FFM of the males was 69,5 kg ± 6,4 and for the females 48,7 kg ±
6,2.
22
females p = 0,648). The muscle strength, split up for gender and different age groups, are shown in
figure 9.
Figure 9: Differences in muscle strength between males and females, split up for the younger and
older participants
Whiskers represents 1 standard deviation
Chapter: 3. Results
These differences in kg FFM in younger and older males and females are in terms of percentage 7,3
percent for males and 2,5 percent for females.
By Dekker I.M & Oudejans J.
23
Chapter: 4. Discussion
By Dekker I.M & Oudejans J.
24
4. DISCUSSION
In the Netherlands 56,6 percent of the elderly (65 years and older) is overweight.32 People with
overweight have significantly more FFM, but not significantly more muscle strength, this is probably
due to the infiltration of fat in the muscles, which causes a decrease in function of the muscles.22 Loss
of muscle function comes along with aging and a combination of the aging process and having
overweight causes a decrease in muscle function and quality of life.5 Our hypotheses are based on
these findings. The main research question of this study is to determine the relation between the
amount of fat free mass and muscle strength.
This study also will be answering the following subquestions:
1) Is the relation between the amount of fat free mass and muscle strength different for
younger (18 – 39 years) and older adults (40 – 76 years)?
2) What is the influence of BMI in the relation between fat free mass and muscle strength?
3) What is the influence of gender in the relation between fat free mass and muscle strength?
The present study expect that FFM and muscle strength are significantly related to each other and
that age, BMI and gender gave a significant interaction in the relation between FFM and muscle
strength.
The results of this study show a significant relation between FFM and muscle strength. Gender gives
a significant interaction in the relation between FFM and muscle strength. On the other hand, there
are no significant differences in the relation between FFM and muscle strength in younger and older
adults and in the low BM and high BMI group.
4.1 The amount of fat free mass in relation to muscle strength
Koster et al. also found no relation between FFM and muscle strength. They investigated males and
females aged 70-79 years from ‘The Health ABC Study’. The decline of muscle strength was
independent of FFM and similar results were found for muscle quality. The equal rate of decline in
muscle strength and muscle quality suggests that the difference in muscle strength due to a different
fitness level occurred before 70 years. For participants from 70 years and older, exercise might be a
good solution to preserve FFM and maintain muscle strength in old age.34
This difference with the present study and the studies of Rolland and Koster can be explained by the
following reasons: both studies only used participants with a very old mean age, 75-80 years, in
By Dekker I.M & Oudejans J.
Chapter: 4. Discussion
The results from the present study show that when participants have more FFM, they also have
significantly more strength. Our expectation was the same, but Rolland et al. showed that
participants who had more FFM, not significantly had more muscle strength. The study population of
Rolland et al. were obese elderly females, normal weight and lean elderly females with a mean age of
80 years. The obese females had significantly more FFM and muscle mass, but not significantly more
muscle strength. The reason why the elderly obese females have more FFM can be explained by
having more muscle mass. The muscles from the obese females have less strength than the muscles
from the normal weight and lean females. These lower muscle quality in obese persons could be
related to metabolic changes or to changes in muscles, such as fat infiltration.33
25
comparison with present study. Age shows that FFM and muscle strength significantly decreases,
especially in males.27 It is also plausible that Rolland found no relation between FFM and muscle
strength because in the elderly females, muscle strength decreases faster than FFM and therefore
there was no relation found. Another explanation could be that decreases of FFM and muscle
strength are more common in males. The study of Rolland et al. also had a wider range of BMI, lean
females have a mean BMI of 21.6, the normal-weight females have a mean BMI of 26.3 and the
obese females have a mean BMI of 31.9. Because the big differences in BMI, differences between
those three groups were better notable than in the present study. A higher BMI is related to more
FFM, but not to more muscle strength, so these muscles have a decreased quality.33
A study from Reid et al. shows a more similar outcome. The study found, in 57 males and females
with a mean age of 74 years, that there is a strong relation between FFM and muscle strength.
Muscle strength and FFM were significantly greater among males. Regression analyses showed that
an increase in FFM is related to a increase of muscle strength.20 Sternfeld et al. also found a
significant relation between FFM and muscle strength. Greater grip strength was significantly
associated with greater FFM in 1655 males and females with a mean age of 70 years.35
In summary it is not yet clear whether more FFM and muscle strength are related to eachother,
because different studies gave different outcomes. These different outcomes are probably due to
another measurement of FFM and muscle strength, the amount of participants and differences in
characteristics of the study populations.
4.2 Age in the relation between fat free mass and muscle strength
The present study shows that age gives no interaction in the relation between FFM and muscle
strength. Participants with more FFM have more muscle strength but age does not significantly affect
this relation. The present study also examined whether there were differences in FFM between
younger and older males and younger and older females, but no significant differences were found.
The results shows that both younger and older adults have the same amount of FFM and muscle
strength, and that there is no significant difference in the relation between FFM and muscle strength
in the younger and older adults.
A study that matches our expectation about the interaction of age in the relation between FFM and
muscle strength was Delmonico et al. They found that with aging muscle strength declines faster
than muscle mass. They examined 1678 males and females with a mean age of 70-79 years and
found that there is an age related increase in fat infiltration in the muscles in both males and
females. This is indicated by increases of intermuscular fat. With aging the decrease in strength is 2-5
times greater than the loss of muscle mass. Regardless of changes in muscle mass, increased fat
By Dekker I.M & Oudejans J.
Chapter: 4. Discussion
Our expectations were that age gives a significant interaction in the relation between FFM and
muscle strength because the amount of muscle mass and muscle strength decreases when people
are getting older. As described earlier, this losses is called sarcopenia and begins in the fourth decade
of life (30 – 39 years).2 Another expectation of the present study is that there are differences in FFM
between the younger and the older group.
26
infiltration and muscle weakness will develop with age. This implicates loss of muscle quality. Muscle
strength declines in a more rapid rate than muscle mass.36
Another study that matches our expectation about the differences in the older and younger group
was Kyle et al. The participants were males and females aged 18 - 94 years. FFM and muscle mass are
significantly lower within the older participants. FFM and muscle mass were investigated separated
from each other. They found a larger percentage of decrease in muscle mass than FFM. The decline
of FFM and muscle mass is accelerated in males and females after 60 years of age and FFM and
muscle mass are significantly lower than in younger males and females. Fat mass increases until
around 75 years.28
It is remarkable, in the present study, that age give no significant interaction in the relation between
FFM26 and muscle strength and that there are no differences between the different age groups. This
can be explained by the following reason; muscle strength is peaking at the age of 25 – 35 years.37
FFM and muscle strength remains to be stable until the age of 60 years. After this age the change in
FFM and muscle strength accelerates.28 37 With aging the density and the amount of muscles
decreases.38 When the density decrease, the amount of fat in the muscles increases. Therefore the
quality of muscles diminish; elderly people have less kg muscle strength per kg muscle mass.22 38
Diminishing muscle strength is associated with poor physical functioning27 and could change different
abilities in daily life.39 The mean age of the present study is 40 years old, thus our study population is
probably too young to find a significant interaction of age in the relation between FFM and muscle
strength and to find a difference between the younger and the older group.
4.3 BMI in the relation between fat free mass and muscle strength
The present study showed no significant interaction of BMI in the relation between FFM and muscle
strength. Within gender there are no significant differences in muscle strength between the high BMI
group and the low BMI group.
Rolland et al. examined three different groups of elderly females with a mean age 80 years. The
obese females have a mean BMI of 31.9, the normal-weight females have a mean BMI of 26.3 and
the lean females have a mean BMI of 21.6. The obese females have significantly more fat mass, FFM
and muscle mass but the muscle strength was not significantly higher in the group with the obese
females compared to the other groups. These results confirm that factors, other than those who are
related to muscle size, contribute strength measures such as fat infiltration in the muscles.33
It is remarkable that BMI gives no interaction in the relation between FFM and muscle strength in the
present study. This is probably due to the mean BMI of the participants. The participants in the
present study population have a mean BMI of 31,6 ± 4,5. This BMI does not corresponds with the
participants from Rolland et al., which include a larger BMI range. The BMI groups in our study are
By Dekker I.M & Oudejans J.
Chapter: 4. Discussion
The present study expect that BMI gives a significant interaction in the relationship between FFM
and muscle strength, because a higher BMI is associated with a increase of muscle mass, but also a
lower muscle density. A lower muscle density is associated with an increase in intermuscular lipids
and a decreased function of the muscles.22
27
close to each other. Therefore its logical that Rolland et al. found differences between the low BMI
group and the high BMI group, and we do not.
4.4 Gender in the relation between fat free mass and muscle strength
The present shows a significant relation between FFM and muscle strength in all participants. Since
gender appears to be an effect modifier in the relation between FFM and muscle strength, the
relation between FFM and muscle strength is split up for males and females. Both males and females
have a significant relation between FFM and muscle strength. Other outcomes are that males have
significantly more FFM and are significantly stronger than females. It is notable that males have 57
percent more strength per kg FFM than females, which means that the muscle quality of the males is
significantly better than the females.
Our expectation was that gender gives a significant interaction in the relation between FFM and
muscle strength, because males have more FFM, are stronger, have a higher muscle quality and
produce more power than females.29
According to our knowledge only a study from Rolland et al. found no significant relation between
muscle mass and muscle strength in obese elderly females, this is difference in outcome probably
due to the differences in characteristics of the study populations.33
Various studies found the same results as the present study. In a study from Payette et al. for
example they found a significant interaction between FFM and muscle strength in females.26
Sternfeld et al. shows that an increasing of the FFM is associated with an increasing of muscle
strength in males and females.35
Newman et al. and Reid et al. found that the females have significantly more fat mass.20 40 The
females in the present study have 11 percent more fat mass than males and this difference is also
significant.
In a study from Kyle et al. the males have a higher peak of FFM than the females.28 Reid et al. and
Hughes et al. also found that males have a greater FFM.20
Different studies shows that males are significantly stronger than females.29 35 37 Katsiaras et al thinks
that these differences in gender are caused by qualitative and quantitative changes in muscles.29
Lynch et al. suggest that differences in strength between gender may caused by muscle quality.37
Almost all studies found the same results, which is logical because of the differences in body
composition, muscle strength and muscle quality in males and females.
The present study has its strengths and limitations. A limitation is that only FFM is measured and not
muscle mass. The BodPod only measures body volume, body density, fat mass and FFM.41
Another limitation of this study is the age of the participants. The mean age of the participants is 40
years. The younger (< 40 years) and older (≥ 40 years) groups are based on the median age of all the
participants. In a study from Kyle et al28 they investigated differences in FFM in a younger and an
older group. The younger group are participants < 60 years and the older group are participants ≥ 60
years. This average age is 20 years older. Since changes in FFM and muscle strength accelerates after
By Dekker I.M & Oudejans J.
Chapter: 4. Discussion
4.5 Strengths and limitations
28
the age of 60 years,28 37 our study population is probably too young to draw conclusions whether the
relation between the FFM and muscle strength is different in younger and older adults.
A third limitation of the present study is the small amount of participants and the small amount of
male participants. With these amounts it is difficult to draw a conclusion.
Chapter: 4. Discussion
The strength of the present study lies in the measuring of FFM with the BodPod. Because the BodPod
is a valid and accurate method of measuring body composition. This is found in several studies who
compared BodPod to DXA and found that there was no significant difference in measuring body fat
for both instruments.42 43
Another strength of this study is the measurement of muscle strength with the JAMAR® Hydraulic
Hand Dynamometer, because it is a good and simple measurement of muscle strength. Handgrip
strength is strongly related with lower extremity muscle strength,4 knee extension torque and calf
cross-sectional muscle area. Low muscle strength is a clinical marker of poor mobility and a better
predictor of clinical outcomes than low muscle mass.41
By Dekker I.M & Oudejans J.
29
Chapter: 4. Discussion
By Dekker I.M & Oudejans J.
30
5. CONCLUSION AND RECOMMENDATIONS
In conclusion, our study indicates that there is a significant relation between FFM and muscle
strength. This relation is not different in younger and older participants and in participants with a low
or high BMI. Gender gives an interaction in relation between FFM and muscle strength and
investigators should always investigate this relation for males and females separately.
Chapter: 4. Discussion
The isometric handgrip dynamometer is a good and simple instrument to measure muscle strength
by the elderly. Elderly who lose weight also lose muscle mass and thereby muscle strength. Low
muscle strength is associated with a higher risk of mobility limitations, so it is important to watch the
muscle strength in the elderly. We recommend specialist who work with elderly who lose weight to
use the isometric handgrip dynamometer to measure the muscle strength.
By Dekker I.M & Oudejans J.
31
Chapter: 4. Discussion
By Dekker I.M & Oudejans J.
32
6. REFERENCES
1
Sociale monitor [database on the Internet]. Centraal bureau voor de Statistiek. 2010. Available
from:
http://statline.cbs.nl/StatWeb/publication/?VW=T&DM=SLNL&PA=70115ned&D1=0,34&D2=a&D3=a
&HD=081106-1151&HDR=T,G1&STB=G2
2
Karakelides H, Nair K.S. Sarcopenia of aging and its metabolic impact. CurrTop Dev Biol. 2005; 68: p.
123-48 [ABSTRACT]
3
Goodpaster B.H, Park S.W, Harris T.B, Kritchevsky S. B, Nevitt M, Schwartz A.V, Simonsick E.M,
Tylavsky F.A, Visser M, Newman A.B. The loss of skeletal muscle strength, mass, and quality in older
adults: the Health, aging and body composition study. J Gerontol A Biol Sci Med Sci. 2006; 61(10): p.
1059-64
4
Alfonso J, Cruz-Jentoft, Baeyens J.P, Bauer J.M, Boirie Y, Cederholm T, Landi F, Martin F.C, Michel
J.P, Rolland Y, Schneider S.M, Topinková E, Vandewoude M, Zamboni M. Sarcopenia: European
consensus on definition and diagnosis, Report of the European Working Groep on Sarcopenia in
Older people. Age and Aging Advance Access. 2010; 10: p. 1 – 12
5
Wolfe R.R, Miller S.L, Miller K.B. Optimal protein intake in the elderly. Clinical Nutrition. 2008; 27: p.
675 – 684
6
Lamberts S.J.W, Beld A.W. van den, Lely A.J van der. The endocrinology of aging. Science. 1997; 278:
p. 419 – 424
7
Kostka T, Arsac L.M, Particot M.C, Berthouze S.E, Lacour J.R, Bonnefoy M. Leg extensor power and
dehydroepiandrosterone sulfate, insulin-like growth factor-I and testosterone in healthy active
elderly people. Eur J Appl Physiol. 2000; 82: p. 83 – 90
8
Stenholm S, Harris T.B, Rantanen T, Visser M, Kritchevsky S.B, Ferruci L. Sarcopenic obesity –
definition, etiology and consequences. Curr Opin Clin Nutr Metab Care. 2008; 11 (6): p. 693 – 700
9
Houston D.K, Nicklas B.J, Ding J, Harris T.B, Tylavsky F.A, Newman A.B, Lee J.S, Sahyoun N.R, Visser
M, Kritchevsky S.B. Dietaty protein intake is associated with lean mass change in older, communitydwelling adults; the Health, Aging, and Body Compostion (Health ABC) Study. Am J Clin Nutr 2008;
87: p. 150 – 155
10
Koopman R, Loon L.J.C van. Aging, exercise, and muscle protein metabolism. J Appl Physiol. 2009;
106; p. 2040 – 2048
11
12
Koopman R, Walrand S, Beelen M, Gijsen A.P, Kies A.K, Boirie Y, Saris W.H.M, Loon L.J.C. van.
Dietary protein digestion and absorption rates and the subsequent postprandial muscle protein
synthetic response do not differ between young and elderly men. The Journal of Nutrition. 2009; 07:
p. 1707 – 1713
By Dekker I.M & Oudejans J.
Chapter: 4. Discussion
Katsanos C.S, Kobayashi H, Sheffield-Moore M, Aarsland A, Wolfe R.R. A high proportion of leucine
is required for optimal stimulation of the rate of muscle protein synthesis by essential amino acids in
the elderly. Am J Physiol Enodcrinol Metab. 2006; 02: p. 381 – 387
33
13
Het voedingscentrum. De Voedselconsumptiepeiling (VCP) in Nederland. Zuivel en gezondheid.
Tno. Index. Deel 1. B tabel 34. 09-12-1998. http://www.zuivelengezondheid.nl/tno/Index/Deel1/b_tabel_34.PDF
14
Visser M, Goodpaster B.H, Kritchevsky S.B, Newman A.B, Nevitt M, Rubin S.M, Simonsick S.M,
Harris T.B. Muscle mass, muscle strength, and muscle fat infiltration as predictors of incident mobility
limitations in well-functioning older persons. Journal of Gerontology. 2005; 3: p. 324 – 333
15
Goodpaster B.H, Chomentowski P, Ward B.K, Rossi A, Glynn N.W, Delmonico M.J, Kritchevsky S.B,
Pahor M, Newman A.B. Effects of physical activity on strength and skeletal muscle fat infiltration in
older adults: a randomized controlled trail. J Appl Physiol 2008; 105: p. 1498 – 1503
16
Peterson M.J, Giuliani C, Morey M.C, Pieper C.F, Evenson K.R, Mercer V, Cohen H.J, Visser M, Brach
J.S, Kritchevsky S.B, Goodpaster B.H, Rubin S, Satterfield S, Newman A.B, Simonsick E.M.
Physical Activity as a Preventative Factor for Frailty: The Health, Aging, and Body Composition Study.
Journal of Gerontology: Medical Sciences 2009; 1: p. 61 -68
17
Tang J.E, Moore D.R, Kujbida G.W, Tarnopolsky M.A, Philips S.M. Ingestion of whey hydrolysate,
casein, or soy protein isolate: effects on mixed muscle protein sysnthesis at rest and following
resistance exercise in young men. J Appl Physiol 2009: 107; p. 987 – 992
18
Brach J.S, Simonsick E.M, Kritchevsky S, Yaffe K, Newman A.B. The association between physical
function and lifestyle activity and exercise in the Health, aging and body composition study. JAGS.
2004; 52: p. 502 – 509
19
Bonnefoy M, Jauffret M, Jusot J.F. Muscle power of lower extremities in relation to functional
ability and nutritional status in very elderly people. The Journal of Nutrition, Health & Aging. 2007: 11
p. 223 – 228
20
Reid K.F, Naumova E.M, Carabello R.J, Phillips E.M, Fielding R.A. Lower extremity muscle mass
predicts functional perfomance in mobility-limited elders. J Nutr Health Aging. 2008; 12 (7): p. 493 –
498
21
Buchman A.S, Wilson R.S, Boyle P.A, Tang Y, Fleischman D.A, Bennet D.A. Physical activity and leg
strength predict decline in mobility performance in older persons. J Am Geriatr Soc. 2007; 55: p. 1618
– 1623
22
Goodpaster B.H, Carlson C.L, Visser M, Kelley D.E, Scherzinger A, Harris T.B, Stamm E, Newman,
A.B. Attenuation of skeletal muscle and strength in the elderly: The health ABC study. J Appl Physiol.
2001; 90: p. 2157 – 2165
Zelfgeraporteerde medische consumptie, gezondheid en levensstijl [database on the Internet].
Centraal Bureau voor de Statistiek. 2008. Available from:
http://statline.cbs.nl/StatWeb/publication/?DM=SLNL&PA=03799&D1=267-271&D2=017&D3=0&D4=a&VW=T>
24
Rolland Y, Lauwers-Canses V, Cristine C, Kan G.A. van, Janssen I, Morley J.E, Vellas B. Difficulties
with physical function associated with obesity, sarcopenia, and sarcopenic-obesity in communitydwelling elderly women: the EPIDOS (EPIDemiologie l’OSteoperose) study. Americal Journal of
Clinical Nutrition. 2009; 6: p. 1895 – 1900
By Dekker I.M & Oudejans J.
Chapter: 4. Discussion
23
34
25
Lim S, Kim J.H, Yoon J.W, Kang S.M, Choi S.H, Park Y.J, Kim K.W, Lim J.Y, Park K.S, Jang H.C.
Sarcopenic obesity: prevalence and association with metabolic syndrome in the Korean longitudinal
study on health and aging. Diabetes Care. 2010; 7: p. 1652 – 1654
26
Payette H, Hanusaik N, Boutier V, Morais J.A, Gray-Donald K. Muscle strength and functional
mobility in relation to lean body mass in free-living frail elderly women. European Journal of Clinical
Nutrition 1998; 52: p. 45 – 53
27
Dey D.K, Ingvar B, Lissner L, Steen B. Changes in body composition and its relation to muscle
strength in 75-year-old men and women : A 5-year prospective follow-up study of the NORA cohort
in Göteborg, Sweden. Elsevier Inc. 2009: 25; p. 613 – 619
28
Kyle U.G, Genton L, Hans D, Karsegard L, Slosman D.O, Pichard C. Age-related differences in fat-free
mass, skeletal muscle, body cell mass and fat mass between 18 and 94 years. European Journal
Clinical Nutrition. 2001: 55; p. 663 – 672
29
Katsiaras A, Newman A.B, Kriska A, Brach J, Krishnaswami S, Feingold E, Kritchevsky S.B, Li R, Harris
T.B, Schwartz A, Goodpaster B.H. Skeletal muscle fatigue, strength, and quality in the elderly: the
Health ABC Study. J Appl Physiol. 2005; 99: p. 210 – 216
30
Tucker L.A, Thomas K.S. Increasing total fiber intake reduces risk of weight and fat gains in women.
J nutr 2009; 139: p. 576 – 581
31
Constantin-Teodosiu D, Young S, Wellock F, Short A.H, Burden R.P, Morgan A.G, Greenhaff P.L.
Gender and age differences in plasma carnitine, muscle strength, and exercise tolerance in
haemodialysis patients. Nephrol Dial Transplant 2002; 17: p. 1808 – 1813
32
Zelfgeraporteerde medische consumptie, gezondheid en levensstijl [database on the Internet].
Centraal Bureau voor de Statistiek. 2008. Available from:
http://statline.cbs.nl/StatWeb/publication/?DM=SLNL&PA=03799&D1=267-271&D2=017&D3=0&D4=a&VW=T>
33
Rolland Y, Lauwers-Cances V, Pahor M, Fillaux J, Grandjean H, Vellas B. Muscle strength in obese
elderly women: effect of recreational physical activity in a cross-sectional study. Am J Clin Nutr. 2004
; 79: p. 552 – 557
34
Koster A, Visser M, Simonsick E.M, Yu B, Allison D.B, Newman A.B, Eijk J.T.M. van, Schwartz A.V,
Satterfield S, Harris T.B. Association Between Fitness and Changes in Body Composition and Muscle
Strength. JAGS. 2010; 58: p. 219 – 226
35
Sternfeld B, Ngo L, Satariano W.A, Tager I.B. Associations of Body Composition with Physical
Performance and Self-reported Functional Limitation in Elderly Men and Women. American Journal
of Epidemiology. 2002; 2: p. 111 – 121
Delmonico M.J, Harris T.B, Visser M, Park S.W, Conroy M.B, Velasquez-Mieyer, P, Boudreau, R,
Manini, T.M, Nevitt, M, Newman, A.B, Goodpaster, B.H. Longitudinal study of muscle strength,
quality, and adipose tissue infiltration. Am J Clin Nutr. 2009; 90: p. 1579 – 1585
37
Lynch N.A, Metter E.J, Lindle R.S, Fozard J.L, Tobin J.D, Roy T.A, Fleg J.L, Hurley B.F. Muscle quality.
I. Age-associated differences between arm and leg muscle groups. J Appl Physiol. 1999: 86; p. 188 –
194
By Dekker I.M & Oudejans J.
Chapter: 4. Discussion
36
35
38
Frontera W.R, Hughes V.A, Fielding R.A, Fiatarone M.A, Evans W.J, Roubenoff R. Aging of skeletal
muscle: a 12-yr longitudinal study. J Appl Physiol. 2000; 88: p. 1321 – 1326
39
Narici M.V, Maganaris C.N, Reeves N.D, Capodaglio P. Effect of aging on human muscle
architecture. J Appl Physiol. 2003: 9; p. 2229 – 2234
40
Newman A.B, Lee J.S, Visser M, Goodpaster B.H, Kritchevsky S.B, Tylavsky F.A, Nevitt M, Harris B.H.
Weight change and the conservation of lean mass in old age: the Health, Aging and Body
Composition Study. Am J Clin Nutr 2005; 82: p. 872 – 878
41
Fields D.A, Higgins P.B, Hunter G.R. Assessment of body composition by air-displacement
plethysmography: influence of body temperature and moisture. Dynamic Medicine 2004; p. 3
42
Maddalozzo G.F, Cardinal B.J, Snow C.M. Concurrent validity of the BODPOD and dual x-ray
absorptiometry techniques for assessing body composition in young women. J Am Diet Assoc. 2002;
102: p. 1677 – 1679
43
Chapter: 4. Discussion
Frisard M.I, Greenway F.L, Delany J.P. Comparison of methods to assess body composition changes
during a period of weight loss. Obes Res. 2005; 13: p. 845 – 854
By Dekker I.M & Oudejans J.
36
APPENDIX 1: MUSCLE PRESERVATION STUDY
The primary objective of the Muscle Preservation Study (MPS) is to investigate the superiority of a
specialized oral nutritional supplement taken for 13 weeks on preservation of muscle mass during a
weight loss program consisting of a hypo-caloric diet and a resistance exercise program in elderly
(from 55 to 85years) in comparison with a control product
To investigate this topic, the MPS chooses to make a randomized, controlled, bouble-blind, parallelgroup study. The subjects have to sign an informed consent.
After that the participants are screened, the subjects eligible for participation are randomly assigned
to receive either the active product or the control product for a period of 13 weeks. Both groups will
be enrolled in a hypo-caloric weight loss diet and participate in a resistance exercise program
comprising 3 supervised group sessions per week at the study centre.
At baseline and after 7 and 13 weeks subjects visit the study centre for assessments of body
composition, muscle strength, physical functioning and quality of life. Compliance, gastrointestinal
tolerance and adverse events will be checked during the 2-weekly dietary counseling sessions.
Measurements
To answer the research questions of this study the data of the following measurements were used;
- DXA to measure appendicular muscle mass (in kg and % of body weight).
- BodPod to measure fat mass (in kg and % of body weight).
- BIA to measure muscle mass and fat mass (in kg and % of body weight).
- Weight scale to measure body weight.
- Waist circumferences (in cm).
- Isometric handgrip dynamometer to measure muscle strength (in kg).
- 1-RM test to measure 1-RM for leg extension (in Nm).
- Gait speed test (4m walk) 400 m Walk test to measure physical functioning.
- Walking test (400 m walk) to measure physical functioning.
- Chair stand test (rise from a chair with arms crossed) to measure physical functioning.
By Dekker I.M & Oudejans J.
Chapter: 4. Discussion
In- and exclusioncriteria
The participants of the MPS are eligible for the study if they are aged from 55 to 85 years, have a BMI
> 30 or a BMI > 28 and a waist circumference of > 88 cm (females), > cm 102 (males). The
participants need to maintain their dietary habits, participate the study visits and take the study
product every day. A physiotherapist professional evaluate if the participants are physically fit and
whether it is safe to do the exercise program and physical tests.
Participants are excluded from participation if they have had any malignant diseases in the last five
years except for adequately treated prostate cancer without evidence of metastases, localized
bladder cancer, cervical carcinoma in situ, breast cancer in situ or non-melanoma skin cancer or if
they had kidney failure, liver failure and anemia or are taking the following medications:
corticosteroids, immunosuppressants and insulin. Participants are also excluded from participation if
they participate in a weight loss program three months before the start of the study, use proteincontaining or amino acid-containing nutritional supplements, participate in a resistance exercise
program or had an alcohol or drugs abuse. They are also excluded from participation if they use more
than 10 µg of daily vitamin D from medical sources, more than 500 mg of daily calcium intake from
medical sources or if they are allergic to milk and milk products.
37