Does body composition relate to physical
performance in older (55 years and over)
overweight adults?
Bacheloropleiding Voeding & Diëtetiek Hogeschool van Amsterdam
2014202, juni 2014 Daan van Geebergen Sofie Krop
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Does body composition relate to physical performance in older (55 years and over) overweight adults?
Auteurs:
Daan van Geebergen Sofie Krop
Irenestraat 6 Drakenstein 13
1756 AK ‘t Zand 1121 HA Landsmeer
Studentnr: 500616746 Studentnr: 500617333
Nummer afstudeerproject: 2014202
Opdrachtgever:
Lector gewichtsmanagement, Dr. ir. Peter J.M. Weijs Hogeschool van Amsterdam
Dokter Meurerlaan 8, 1067 SM Amsterdam Praktijkbegeleiders:
Suzanne van der Plas en Drs. Robert Memelink Docentbegeleider:
Dr. ir. Mariëlle Engberink
Copyright © 2014, D. van Geebergen en S. Krop
© Niets uit deze scriptie mag worden verveelvoudigd of openbaar gemaakt, in enige vorm of op enige wijze, het zij elektronisch, mechanisch of door fotokopieën, zonder voorafgaande toestemming van de auteurs.
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Voorwoord
In deze scriptie leest u de beschrijving van het onderzoek waar wij hard en met plezier aan hebben gewerkt, zodat onze bacheloropleiding Voeding en Diëtetiek aan de Hogeschool van Amsterdam afgerond kon worden. De studies die wij gebruikt hebben voor ons
afstudeeronderzoek hebben ook het effect van eiwitrijke voeding tijdens een afvalprogramma onderzocht, maar wij hebben ervoor gekozen ons op de lichaamssamenstelling en het fysiek functioneren te focussen en het voedingsgedeelte buiten beschouwing te laten. Nadat de keuzemogelijkheid aan ons was voorgelegd, hebben wij ervoor gekozen deze scriptie te schrijven in de vorm van een Engelstalig wetenschappelijk artikel.
Zonder de hulp van verscheidene mensen hadden wij deze studie niet zo goed kunnen uitvoeren. We willen het onderzoeksteam; Madelief Jambroes, Linda Zevenhek, Hetty Korsten, Suzan Bakker, Eva Sayers, Sadia Rodjan, Kim Schut en Loïs Kaersenhout, bedanken voor hun medewerking aan dit onderzoek. Onze dank gaat ook uit naar Suzanne van der Plas, die het onderzoek in goede banen heeft geleid en Robert Memelink die een grote hulp was bij het analyseren en verwerken van onze onderzoeksresultaten.
Wij bedanken onze docentbegeleider Mariëlle Engberink voor haar fijne begeleiding en hulpvolle feedback tijdens het gehele proces. Tenslotte bedanken wij Peter Weijs voor zijn aanwijzingen en kritische blik.
Daan van Geebergen en Sofie Krop Amsterdam, juni 2014
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Abstract
How does body composition relate to physical performance?
The relation between body composition and physical performance in older (55 years and over) overweight adults.
Background/ objectives: Previous research showed that BMI could not be used to show a
relationship with physical performance. Further investigation was needed for a better understanding of how body composition might influence the physical performance in older adults (55 years and over) and how this relates to overweight and obesity.
Subjects/ methods: 159 older adults (55 years and over) from two weight-loss trials were
included in this study. Body composition (body weight, fat mass, lean mass and waist circumference) and physical performance (handgrip strength, chair stand test, usual walking speed (4m gait speed) and maximal walking speed (400m walking test)) were evaluated at baseline and after intervention. Regression analysis was applied to evaluate the relation between body composition and physical performance and the change in body composition related to change in physical performance. These models were adjusted for age, gender and height. In body composition fat mass was corrected for lean mass.
Results: Subjects were 65.4% female, mean age was 62.9 ±5.6 years. Mean BMI was 32.7
(± 4.26) and mean body weight was 93.1 ±13.7kg. At baseline body weight alone showed little specific relation with physical performance after adjustment for confounders. Looking at what body weight is built up from; lean mass and fat mass. If a person has more lean mass or less fat mass, handgrip strength is stronger (β [lean mass %]= 0.23, p= 0.01, R² 0.66, β [lean mass kg]= 0.33, p <0.001, R² 0.68 and β [fat mass %]= -0.23, p= 0.01, R² 0.66). Looking at how changes in body composition and changes in physical performance, caused by the intervention, were related to each other. The only significant overall relation shown was an increase in waist circumference with a decrease in the 400m walking speed (β= -0.005, p =0.04, R² 0.01).
Conclusions: Findings from this study show that there was a relation between a higher lean
and lower fat mass and a more powerful handgrip strength in older (55 years and over) overweight adults After a weight loss intervention, looking at changes, the only significant relations overall are shown in increases in waist circumference with decreases in the 400m walking speed. A larger study needs to be performed to get a clearer view on the relation between changes in body composition and changes in physical performance.
Keywords: older adults, overweight, obesity, fat mass, lean mass, weight loss, resistance training, physical performance, body composition.
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List of abbreviations
BMI: Body Mass Index
MPS: Muscle Preservation Study Welprex: Weight loss, protein, exercise
ADP: Air Displacement Plethysmography DEXA: Dual Energy X-ray Absorptiometry
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T
ABLE OF
C
ONTENTS
Concept article
Background ...13
Methods ...15
Study design and study population ... 15
Measurements ... 16
Statistical analysis ... 16
Results ...17
Population characteristics and primary study outcomes ... 17
Relation of body composition and physical performance at baseline ... 18
Relation between changes in body composition and physical performance ... 20
Discussion ...23
Results... 23
Strengths and Limitations ... 23
Conclusion ... 24
References ...25
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BACKGROUND
Worldwide, the prevalence of overweight and obesity has nearly doubled since 1980 (1). In 2008, 200 million men and nearly 300 million women were obese. In total 35% of the adults were overweight (1). The past 20 years the number of older adults aged 65 years and over, has increased from 12.8% to 15.6%. Almost 60% of these older adults of 55 years and over in the Netherlands are overweight or obese (2-4). The consequences of overweight and obesity are serious health threats, such as diabetes, cardiovascular diseases and cancer (5,6).
For older adults physical function is an important factor for health and overall wellbeing. When people grow older their body composition changes; fat free mass decreases and fat mass increases over time (7). The decline in fat free mass is increased in people older than 60 years. Fat mass continues to increase until people are about 75 years old (8). It has been suggested that body composition had a relation with physical performance. Studies show that a high body fat percentage has a more negative relation with walking speed, when people become older. The effect is best shown at the age 60-79 years. This would mean that a high fat percentage is more harmful to the physical performance when adults are in their sixties and seventies (9).
A modest weight loss of 5-10% has beneficial health effects (10). When people participate in a weight loss program, the results may vary depending on the kind of weight loss program. If a diet alone is prescribed, there is a weight loss in total body mass. If a diet is combined with resistance training, fat free mass remains and fat mass decreases. The combination of a diet and resistance training may also effectively reduces coronary heart disease risk factors and has a positive effect on the diet quality (11-13).
The weight categories (normal weight, overweight, obesity, etc.) are displayed in Body Mass Index (BMI) only. The use of BMI as a measure of excess body weight may lead to some misclassification, as it does not distinguish between fat mass and lean mass. Furthermore, it is never tested if the physical performance is improved and at which level, when there is a decrease in BMI (14).
In a recent (2012) randomized controlled trial, done by Beavers et al., the relationship between changes in body weight, fat mass and lean mass and changes in physical
performance were investigated from a group of 271 adults of 50 years and over. It showed that only a change in fat mass could significantly predict the decrease in mobility disability (β 0.04; p <0.01) and increase in walking speed (β -0.01; p <0.01) (15). A study has shown that because elderly women (70-79 years) have a higher fat mass then men, their physical function is poorer. Walking speed and the chair stand test were used to test physical performance (16). Higher fat mass and lower lean mass are related to poorer physical performance in women (56 ±4.4 years) with a body mass of 31 ±4.6 kg/m² (17). Fragala (2010) shows the differences in anthropometric predictors of physical performance in older men and women. Participants were 470 older men and women (72.9 ±7.9 years). BMI shows a difference in relation towards physical performance in men and women because of the difference in lean mass en fat mass amongst men and women. In women a relation between BMI and physical performance is shown. In men the relation is only shown in muscle quality and physical performance. BMI could not be used to show a relationship with physical performance (13).
Further investigation is needed for a better understanding of how body composition might influence the physical performance while getting older and also how this influences an overweight or obese elderly population (12). Therefore, in the present study, we investigate the relationship between body composition and physical performance in elderly people (55 years and over) who are overweight.
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METHODS
STUDY DESIGN AND STUDY POPULATION
The present analysis included 159 older adults with overweight who participated in two randomized controlled weight loss trials performed at the Amsterdam University of Applied Science in The Netherlands at the Department of Nutrition and Dietetics between 2009 and 2013. Both studies assessed measurements of body composition and physical performance before and after intentional weight loss. Table 1 contains descriptions of the population of both studies by gender, age, intervention duration and targeted strategy and goals. Because of missing data, the number of participants varies at baseline and when looking at changes in body composition and changes in physical performance, more data was missing. Primary outcome of these studies was the effect of protein intake and resistance training on body composition and physical performance. In the present study, we evaluated if there was a relation between body composition and physical performance.
Inclusion criteria of the two trials were as follows: aged over 55 years, not engaged in a regular exercise program (within the past 3 months), BMI of ≥28 kg/m2 or ≥25 kg/m2 with a
waist circumference ≥88cm (women) or ≥102cm (men), ability to safely engage in moderate exercise and medical clearance. Participants were eligible for participation when they were willing and able to comply with the study protocol, which included following a hypocaloric diet, participation in study visits, ability to understand and fill out questionnaires and were physical screened by a professional physical therapist. Participants were excluded if there was a presence of acute or chronic condition such as; renal failure, cardiovascular disease, diabetes mellitus with insulin, exercise asthma, dysfunction of joints, use of antidepressant (<1 year), thyroid dysfunction, known allergy to milk and milk products or known
galactosaemia. The participants filled out an informed consent and both protocols were approved by the Medical Ethical Committee.
Table 1: Description of the weight-loss trials used in the present study/analysis
Study name Welprex MPS
n (M:F) 79 (23:56) 80 (32:48)
Age (y) 55-78 55-77
Intervention duration 10 weeks 13 weeks
Strategy and Goals A 10-week weight loss program with a hypocaloric diet and resistance exercise. Participants were divided into four groups; high protein, high protein + resistance training, regular diet + resistance training, regular diet (control group).
The aim was to evaluate the effects of the intervention on improvement of body
composition, physical function and quality of life in an
overweight elderly (55+) population.
A 13-week double blind weight loss program with a
hypocaloric diet and resistance exercise.
One of the groups had to drink 10 protein shakes a week. The aim was to evaluate the effects of a protein
supplement on the
preservation of muscle mass in an overweight elderly (55+) population.
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MEASUREMENTS
At baseline and after 10 weeks (Welprex) or 13 weeks (MPS), body composition and physical performance were measured. Trained students executed all measurements. Each student executed the measurements for a fixed group of participants. The participants were asked not to eat 5 hours before the measurement and drink only water until one hour before. Exercise and sauna use were not allowed the day before. Jewelry, watches and glasses were not allowed during the measurements.
Body composition
Height (cm) was measured with a stadiometer (DGI 250D) and weight was measured with a calibrated scale (kg) (Cosmed). Fat free mass (%, kg) and lean mass (%, kg) were
determined with an Air Displacement Plethysmography (ADP) (Bodpod, Cosmed). The validity and reproducibility of the body composition data while using the ADP is reported previously (18, 19). In the ADP the participants were required to wear tight underwear and a swimming cap and were supposed to sit still for the duration of the test. The test was done twice and the mean was taken into account with data analysis. Before the measurements the ADP and the scale were calibrated every morning and between every participant. Waist circumference (cm) was measured with a tape measure between the lowest rib-bones and the top of the hipbones.
Physical performance
Four tests were used to measure physical performance. For testing muscular strength we used the handgrip strength-test by using a hydraulic hand dynamometer (kg)(JAMAR). The measurement was performed three times with each hand. The participant was sitting on a chair, holding his arm in an angle of 90 degrees and was supposed to squeeze the
dynamometer as vigorous as possible. The mean between left and right was calculated. For testing power, the chair stand test was used. The participant had to stand up five times from a sitting position to a straight up stand, without using their arms and as fast as possible (s). Arms were folded over the chest. Time was measured how fast this was completed. All participants had to practice standing up one time to confirm that they were able to perform the test. To measure speed, two tests were used, the gait-speed test and the 400m walking test. At the gait-speed test the participants had to walk 4 meters in their normal walking pace (m/s). Time started running when the participants started moving and ended as soon as one foot completely crossed the finish line. This test was performed twice and the fasted speed was used. The 400-meter walking test was performed over a course of 40m. The participants had to walk 10 laps as fast as possible, without running (m/s). The 10 laps were counted and participants were encouraged consistently by the students during the test.
STATISTICAL ANALYSIS
Double data entry was performed for both studies and discrepancies were solved. Means, proportions and change were calculated overall and by study. Change from baseline to follow-up was calculated by taking follow-up measurement minus baseline measurement. Within each study and overall, to investigate the possible relationship between physical performance and body composition, regression analysis were performed. With each study and overall a regression analysis was performed on the data from the baseline
measurements. The models were adjusted for age, gender and height. In body composition fat mass (kg) was corrected for lean mass (kg). Regression analysis between changes in body composition and changes in physical performance were performed to see if there was a significant relation. These models were adjusted for age, gender and height. In body
composition fat mass (kg) was corrected for lean mass (kg). The models were created for each study and overall.
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RESULTS
POPULATION CHARACTERISTICS AND PRIMARY STUDY OUTCOMES
Baseline characteristics for participants and primary study outcomes are presented in Table 2. The total study populations (N=159) mean age was 62.9 ±5.6 years and the majority of the group was female 65.4%. BMI was 32.7 ± 4.3kg/m² and body weight was 93.1 ±13.7kg. After the weight loss trail BMI decreased with 1.09 ±1.02kg/m² (p = 0). The overall body weight decreased with 3.2 ±3.0kg (p = 0). Lean mass increased with 0.4 ±1.8kg (p = 0.018) while fat mass decreased with 3.6 ±3.2kg (p = 0). With respect to physical performance hand grip strength increased with 1.4 ±4.5kg (p =0.001) and chair stand test time decreased with 1.8 ±3.2 seconds(p = 0), while gait speed increased with 0.02 ±0.21m/s (p = 0.41) and 400m walking speed increased with 0.01 ±0m/s (p = 0.44).
Table 2: Baseline characteristics and change (delta) at end of intervention in overweight adults of 55 years and over.
Variable Overall (N=159) Welprex (N=79) MPS (N=80)
Age (y) 62,9 ±5,6 62,8 ±5,6 62,9 ±5,6 Male/female (%) 34,6/65,4 29,1/ 70,9 40/60 Baseline BMI (kg/m²) 32,7 ±4,3 32,1 ±4,0 33,3 ±4,4 Δ BMI (kg/m²) -1,09 ±1,02 -1,12 ±0,91 -1,07 ±1,1 Body composition Body weight (kg) 93,1 ±13,7 91,3 ±13,4 94,9 ±13,8 Δ Body weight(kg) -3,2 ±3,0 -3,2 ±2,7 -3,1 ±3,2 Lean Mass (%) 56,2 ±8,3 55,8 ±8,1 56,6 ±8,5 Δ Lean Mass (%) 2,5 ±2,6 2,4 ±2,7 2,5 ±2,5 Lean Mass (kg) 52,2 ±10,9 51,0 ±10,9 53,5 ±10,8 Δ Lean Mass (kg) 0,4 ±1,8 0,4 ±2,0 0,4 ±1,5 Fat Mass (%) 43,8 ±8,3 44,2 ±8,2 43,4 ±8,5 Δ Fat Mass (%) -2,5 ±2,6 -2,5 ±2,7 -2,5 ±2,5 Fat Mass (kg) 40,7 ±10,0 40,3 ±9,4 41,1 ±10,6 Δ Fat Mass (kg) -3,6 ±3,2 -3,7 ±3,2 -3,5 ±3,2 Waist circumference (cm) 109,1 ±10,7 107,8 ±10,0 110,4 ±11,2 Δ Waist circumference (cm) -4,4 ±4,1 -4,8 ±3,5 -4,1 ±4,6 Physical function
Hand Grip Strength(kg) 30,4 ±10,1 31,3 ±10,5 29,6 ±9,7 Δ Hand Grip Strength(kg) 1,4 ±4,5 0,5 ±4,5 2,1 ±4,3 Chair stand test (s) 13,7 ± 4,0 12,6 ±3,4 14,8 ±4,2 Δ Chair stand test (s) -1,8 ±3,2 -1,7 ±2,8 -1,9 ±3,6
Gait speed (m/s) 0,94 ±0,24 0,82 ±0,17 1,07 ±0,23
Δ Gait speed(m/s) 0,02 ±0,21 -0,09 ±0,13 0,11 ±0,23
400m walking test (m/s) 1,02 ±0,34 0,71 ±0,10 1,32 ±0,18 Δ 400m walking test (m/s) 0,01 ±0,1 -0,04 ±0,06 0,05 ±0,11 BMI= body mass index; n= sample; Δ= change (n=111-119);
Data presented as mean ± SD or n (%). Change data are defined as the follow-up minus the baseline value.
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RELATION OF BODY COMPOSITION AND PHYSICAL PERFORMANCE AT BASELINE
The association between body composition and physical performance is presented in Table 3. After adjustment for gender, age and height, body weight alone shows little specific relation with physical performance. Body weight is built up from lean mass and fat mass. With more lean mass or less fat mass, handgrip strength is higher (β [lean mass %]= 0.23, p= 0.01, R² 0.66, β [lean mass kg]= 0.33, p <0.001, R² 0.68 and β [fat mass %]= -0.23, p= 0.01, R² 0.66). Chair stand test time is positively related to bodyweight, fat mass (kg) and waist circumference (all p <0.05), these results only explain 3% of the variation. Gait speed and 400m walking test show the most significant positive relation with body composition, these results did not show overall but only in the MPS study.
Table 3: Relation between body composition and physical performance at baseline in overweight adults 55 years and over.
Variable Study (N**) Hand grip strength (kg) Chair stand test (s) Gait speed (m/s) 400m walking test (m/s)
β p R² β p R² β p R² β p R²
Body weight (kg) Overall 0,03 0,475 0,66 0,06 0,036* 0,03 0 0,885 0 0,002 0,428 0
MPS 0,06 0,256 0,07 0,111 -0,004 0,058 -0,005 0,002*
Welprex 0,04 0,466 0,02 0,56 0,001 0,624 0,002 0,023*
Lean Mass (%) Overall 0,23 0,01* 0,66 -0,86 0,147 0,02 0,002 0,519 0 0,001 0,898 0,01
MPS 0,23 0,07 -0,15 0,085 0,01 0,034* 0,008 0,024*
Welprex 0,2 0,091 -0,003 0,969 -0,003 0,301 -0,002 0,167
Lean Mass (kg)*** Overall 0,33 0* 0,68 0,04 0,473 0,03 0,001 0,696 0 0,006 0,307 0,01
MPS 0,36 0,004* 0,01 0,954 0 0,983 -0,001 0,784
Welprex 0,35 0,005* 0,05 0,509 -0,003 0,485 0,002 0,389
Fat Mass (%) Overall -0,23 0,01* 0,66 0,09 0,147 0,02 -0,002 0,519 0 -0,001 0,897 0,01
MPS -0,23 0,07 0,15 0,085 -0,11 0,034* -0,008 0,24
Welprex -0,2 0,091 0,003 0,969 0,003 0,301 0,002 0,167
Fat Mass (kg)**** Overall -0,09 0,084 0,68 0,08 0,039* 0,03 -0,001 0,53 0 0 0,952 0,01
MPS -0,06 0,408 0,11 0,03* -0,007 0,021* -0,006 0,003* Welprex -0,09 0,21 0,01 0,887 0,002 0,298 0,002 0,066 Waist circumference (cm) Overall -0,05 0,272 0,65 0,1 0,003* 0,05 -0,001 0,55 0 0,002 0,466 0,01 MPS -0,39 0,557 0,91 0,055 -0,07 0,01* -0,005 0,011* Welprex -0,03 0,708 0,07 0,077 0,002 0,249 0,003 0,001*
Adjusted for gender, age and height; b= Additionally adjusted for fat mass (kg); c= Additionally adjusted for lean mass (kg) a= n Overall = 145-150; n MPS = 71-78; n Welprex = 72-75
RELATION BETWEEN CHANGES IN BODY COMPOSITION AND PHYSICAL PERFORMANCE
Relationship between change in body composition and change in physical performance by study and for both studies combined are presented in Table 4. After adjustment for gender, age and height, the change body weight remained a significant predictor for increase in gait speed (β= 0.018, p =0.046), but only in the MPS study. Changes in lean mass (%), fat mass (kg) and fat mass (%) remained a significant predictor for increase in gait speed for the Welprex study; i.e. (β [fat mass %]= -0.015, p = 0.029, β [fat mass kg]= -0.012, p =0.038 and β [lean mass %]= 0.015, p= 0.029). In the Welprex study change in body weight showed a relation with the increase in 400m walking speed (β= 0.006, p= 0 .035). The only significant relations overall were observed for an increase in waist circumference with a decrease in 400m walking speed (β= -0.005, p =0.04, R² 0.01).
Table 4 Relation between changes in body composition with change in physical function in overweight adults 55 years and over.
Adjusted for gender, age and height; b= Additionally adjusted for fat mass (kg); c= Additionally adjusted for lean mass (kg); Change is defined as follow-up value minus baselin value. a= n Overall = 101-107; n MPS = 53-57; n Welprex = 48-50; * indicates statistical significance
Variable Study
(n=a)
Change in handgrip strength (kg)
Change in chair stand test (s)
Change in gait speed (m/s)
Change in 400m walking test (m/s)
β p R² β p R² β p R² β p R²
Change in
body weight (kg) Overall -0,191 0,18 0,1 -0,114 0,27 0 0,008 0,25 0,01 -0,001 0,71 0,02
MPS -0,004 0,98 -0,179 0,22 0,018 0,05* -0,006 0,2
Welprex -0,384 0,14 -0,071 0,63 -0,011 0,11 0,006 0,04*
Change in
lean mass (%) Overall 0,111 0,51 0,86 0,064 0,6 0 -0,003 0,67 0,02 0,002 0,53 0,02
MPS 0,059 0,79 0,205 0,31 -0,021 0,09 0,006 0,35
Welprex 0,159 0,54 -0,013 0,93 0,015 0,03* -0,001 0,66
Change in
lean mass (kg)(b) Overall -0,16 0,51 0,09 -0,073 0,69 0,01 0,003 0,79 0,02 0,002 0,66 0,02
MPS 0,19 0,59 -0,089 0,79 -0,003 0,9 0,001 0,92
Welprex -0,26 0,46 -0,061 0,76 0,011 0,24 0,003 0,43
Change in
fat mass (%) Overall -0,112 0,5 0,86 -0,064 0,6 0 0,003 0,67 0,02 -0,002 0,53 0,02
MPS -0,059 0,79 -0,205 0,31 0,021 0,09 -0,006 0,35
Welprex -0,163 0,54 0,013 0,93 -0,015 0,03* 0,001 0,66
Change in
fat mass (kg)(c) Overall -0,119 0,38 0,09 -0,054 0,59 0 0,005 0,46 0,02 -0,002 0,54 0,02
MPS -0,044 0,8 -0,125 0,42 0,017 0,07 -0,007 0,17 Welprex -0,173 0,43 -0,025 0,83 -0,012 0,04* 0,003 0,22 Change in waist circumference (cm) Overall -0,008 0,93 0,08 -0,04 0,59 0,01 -0,001 0,87 0,03 -0,005 0,04* 0,01 MPS 0,172 0,11 0,01 0,91 -0,001 0,91 -0,006 0,05* Welprex -0,359 0,07 -0,12 0,21 -0,001 0,8 -0,004 0,13
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DISCUSSION
RESULTS
In the present study we examined if there is a relation between body composition and physical performance in older (55 years and over) overweight adults, using data from two studies performed at the University of Applied Science in Amsterdam at the Department of Nutrition and Dietetics between 2009 and 2013.Conform our prediction there is no clear relation found between body weight and physical performance. In body composition the only explicit significant relation with physical performance shows in lean mass (kg), lean mass (%) and fat mass (%) with handgrip strength.
Our results were in line with results from Straight, et al., where 95 overweight and obese (BMI=33.4±4.0 kg/m²) older adults aged 55-80 years completed an 8-week resistance training and dietary intervention. Mean change in handgrip strength was 1.2±2.5 kg (p<0.001) and mean change in body fat was -0.5±1.4% (p<0.001) (20).
Results from the present study demonstrate that if a person has 5kg more lean mass, he would also have 1.65kg more handgrip strength and 5% higher lean mass means 1.15kg more handgrip strength. An increase in fat mass results in a decrease of handgrip strength. According to a study by Arroyo, handgrip strength was strongly and inversely associated with functional limitations, which means the lower handgrip strength, the higher the risk of
functional limitations (21).
In present study, mean change in lean mass (0.4±1.8kg and 2.5±2.6%) was positive, which could mean there was a gain in muscle mass. This is in contrast with finding from previous studies, even though these studies show that significant loss in lean mass does not result in loss in physical performance (22, 23). Physical performance improvements in relation to the amount of fat mass lost is independent of the amount of lean mass lost (17).
When assessing the relation between changes in body composition and changes in physical performance, less significant relations are shown compared to relations at baseline. In our knowledge there are no other studies that showed and compared baseline relations to relations after an intervention. The only overall significant relation we found is between change in waist circumference and change in 400m walking test. The outcome may be clouded because of the noise that arose during measurements. This noise accumulated when changes were calculated.
STRENGTHS AND LIMITATIONS
Both Welprex and MPS were executed by students. Although the protocols seem similar, corresponding execution methods are questionable. For instance the execution of 400m walking test; In MPS participants were told to walk their normal pace (24), while in Welprex the participants were encouraged to walk as fast as they could without running. This could explain the differences in improvements in the 400m walking test for both studies, as there is no improvement expected when participants are not required to perform at their highest potential. Though there are differences in execution and encouragement, if at baseline and after intervention it was the same within each participant, it is questionable whether it has influenced our results.
The ADP was used to measure body composition in both studies, though dual energy x-ray absorptiometry (DEXA) is becoming popular as an alternative method to measure body composition. In comparison between ADP and DEXA , studies show different results for different populations (25-28). It is uncertain exactly where the difference in the outcome of the measurements lied. We should be aware that determination of body composition was at best, an estimation (29).
24 One of the parameters of physical performance is handgrip strength. In the work field,
handgrip strength is used to map nutritional status and as an indicator for malnutrition (30). In present study, handgrip strength was used to determine physical performance. Possibly handgrip strength might not have been the correct test to measure physical performance, even though it significantly predicted short-term functional outcome in women after a hip-fracture where DEXA assessed appendicular lean mass did not (31). A hydraulic hand dynamometer was used to measure handgrip strength. The output was read in kilograms. It is not easy to assess the exact outcome, as the scale-unit is 2 kg. Using this hand
dynamometer, a part of a kilogram is difficult to rank, therefore the mean change of handgrip strength in present study of 1.35 kg, is nearly impossible to determine. That is evidence that this instrument might not be sensitive enough to observe change at all, especially changes achieved in these interventions.
The group size in the present study at baseline counted 159 participants. After intervention the group size was reduced to 101-107. This reduction was caused by missing data;
measurements that were not performed and intervention drop outs. Because of the reduction in group size, the power of the study also decreased.
The duration of the interventions were 10 weeks (Welprex) to 13 (MPS). This might not have been enough time to achieve a change in body composition that was big enough to show an effect on physical performance (32). In addition, two-thirds of the participants received resistance training. It is expected that a bigger change in body composition and physical performance could be achieved when the participants recieved resistance training. In present study regression analysis were performed on the groups who received resistance training and the groups who did not receive resistance training, to investigate the possible
relationship between physical performance and body composition between those two groups. No overall significant relations were found in this analysis.
Participants for these studies had to have a BMI of at least 25 kg/m². It is expected that if the starting weight is higher, weight loss will be faster. In the present study, mean BMI at
baseline was 32.7 kg/m² (±4.3). If this had been only slightly above 25 kg/m², effects on body composition would probably be lower, therefore could have shown a different relation with physical performance.
In both studies there was an age range of 55 to 78 years. The results could possibly not be generalized for the total population of adults of 55 years and over and especially not for elderly above 80 years. Because when people are older, their body composition changes; lean mass decreases and fat mass increases (8, 9).
Despite limitations, the relation between lean and fat mass and handgrip strength and the relation between waist circumference and 400m walking speed are similar to those presented in previous studies (20, 22 33, 34).
CONCLUSION
In conclusion, findings from this study show that there is a relation between a higher lean and lower fat mass and a more powerful handgrip strength. Looking at changes, the only
significant relations overall are shown in increases in waist circumference with decreases in the 400m walking speed. A larger study needs to be performed to get a clearer view on the relation between changes in body composition and changes in physical performance.
Moreover, more research needs to be done on how the different interventions that were used to achieve those changes, influences the relation.
25
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29
AANBEVELINGEN
De resultaten uit dit onderzoek indiceren dat er niet blind gestaard moet worden op alleen gewichtsverlies in het algemeen, maar dat de lichaamssamenstelling ook een indicatie kan zijn voor het fysiek functioneren. Als we kijken naar andere onderzoeken op dit gebied, blijkt de verbetering in lichaamssamenstelling echter van ondergeschikt belang, voor een
verbetering van fysiek functioneren. De afname van overgewicht betekent een verbetering in het fysiek functioneren onafhankelijk van het verlies van vet vrije massa.
Dit houdt wel in dat je als diëtist niet alleen het gewichtsverloop moet monitoren maar ook het fysiek functioneren in kaart moet brengen. Het uiteindelijk doel van gewichtsverlies is een verbetering in de kwaliteit van leven. Als het fysiek functioneren aan het afnemen is, zoals bij de volwassen van 55 jaar en ouder met overgewicht, dan heeft het een negatieve invloed op de kwaliteit van leven. Het behoudt van fysiek functioneren is belangrijk om de kwaliteit van leven van de volwassen van 55 jaar en ouder met overgewicht te behouden. Het uiteindelijke doel is de zelfredzaamheid zo lang mogelijk te behouden.
Hoe de verandering in fysiek functioneren het beste in kaart gebracht kan worden is nog niet duidelijk naar voren gekomen uit de verschillende onderzoeken. Dat het moet gebeuren is wel belangrijk. Er moet nader onderzocht worden welke testen hiervoor het meest geschikt zijn en die vervolgens ook praktisch toepasbaar zijn voor de diëtist. Zo wordt de diëtist ook breder inzetbaar.
Voeding staat in groot verband met verandering in lichaamssamenstelling. Tijdens dit onderzoek is er niet gegeken naar de invloed van de voeding op verandering van de lichaamssamenstelling. Hierdoor kunnen wij geen aanbevelingen doen op dit gebied. Voor nader onderzoek zou dit een interessant aspect zijn.
