Physical training in obese women

European Journal of
Eur J Appl Physiol (1984) 52:355-361
Applied
Physiology
and Occupational Physiology
9 Springer-Verlag 1984
Physical training in ,obese women
Effects of muscle morphology, biochemistry and function
Konstantinos Mandroukas, Marcin Krotkiewski, Marita Hedberg,
Zet~on Wroblewski, Per Bj6rntorp, and Gunnar Grimby
Department of Rehabilitation Medicine, MedicineI & Plastic Surgery, Sahlgren's Hospital, Universityof G~teborg,
Ovre Husargatan 36, S-41314 G6teborg, Sweden
Summary. Peripheral adaptations to 3 months of
physical endurance training without food restrictions
were studied in skeletal muscles of 14, middle-aged,
physically untrained, obese women.
In comparison to aged-matched controls of normal weight, the obese group showed significantly
lower isometric endurance9 In the obese group,
physical training resulted in a significant increase of
maximal isometric and isokinetic strength. Isokinetic
but not isometric endurance also increased after
training. The isometric strength of obese women
showed a positive correlation with the percentage of
FTb fibres.
The training (50 min/day, 3 days/w) did not result
in any change in body weight, body fat, and the
number and weight of fat cells. The 20% increase of
VO 2 max after training was found to be significantly
correlated with the increase in the number of
capillaries around muscle fibres. The relative percentage of FTa fibres, the number of capillaries per
fibre as well as the activities of citrate synthase,
3-hydroxy-acyl-CoA-dehydrogenase,and hexokinase
showed a significant increase after training9
The concentrations of glucose during OGTT
showed a trend to decrease with a significant decrease
at the end glucose curve (120-min value). The
concentration of insulin and C peptide and the insulin
removal did not change after training9 The changes in
the concentration of glucose during OGTT was
significantly correlated with the increase in muscle
capillarization and of dynamic endurance.
Key words: Obesity - Muscle strength - Fibre
composition - Capillarization - Enzymes - Physical
training
Offprint requests to:
M. Krotkiewstd at the above address
Introduction
Physical training is widely recommended in the
treatment of obesity. However, unless it is combined
with food restrictions, in severely obese subjects
training does not result in a decrease in body weight.
The training causes, however, numerous metabolic
adaptations (Bj6rntorp et al. 1970, 1973a, 1973b;
Krotkiewski et al. 1979, 1980a, 1980b), which can be
considered advantageous in the prevention of metabolic disorders associated with obesity (Sullivan et al.
1981).
Skeletal muscles are important target organs for
insulin and for glucose storage and utilization, while
glucose utilization in adipose tissue is comparatively
small. Neither the number nor weight of fat cells
changes after training in severly obese subjects
(Bj6rntorp et al. 1970, 1973a, 1973b; Krotkiewski et
al. 1979, 1980a, 1980b), while numerous adaptations
have been described in muscle tissue (Andersen and
Henriksson 1977; Josenhans 1962; Petrofsky and
Lind 1975). Physical training increases insulin sensitivity (Bj6rntorp et al. 1970; Sullivan 1976). This
increase may be causally related to the metabolic,
morphologic and/or microvascular adaptations in
muscle tissue9 The aim of the present study was to
examine in detail the adaptation occuring in obese
subjects in skeletal muscles, and to relate them to
general adaptations, such as changes in body composition, Vo2 max, blood pressure, heart rate, and
metabolism.
Material and methods
Fourteen obese middle-agedwomenwere includedin the study.
Their general characteristics are summarized in Table 1. All
patients had sedentaryoccupations and had not been engagedin
any regular physical training programme during the preceding
year. During the period of physical training the patients were
instructed to maintaintheir usualfoodintake and drinkinghabits.
356
No patients included in the study had any signs of cardiovascular or
renal diseases or neurological disorders. There was no drop out
during the training programme. Before starting the training
programme, body weights of the patients were recorded at
intervals during 2 months to ensure body weight stability. All the
women had given their informed consent to the various parts of the
experiments. The local ethical committee at the University of
G6teborg had approved all details of the present study.
Body composition and blood chemistry
Body composition was calculated from 4~ measurements with a
whole body counter. Lean body mass (LBM = whole body without
adipose tissue mass) was calculated according to the formula by
Forbes et al. (1961), which assumes a constant amount of
potassium (68.1 mEq) per kilogram of lean body mass. Body fat
was calculated by substraction of lean body mass from the total
body weight. Subcutaneous fat biopsies were taken from the
epigastric, hypogastric, femoral, gluteal, and upper arm regions
(Krotkiewski et al. 1977).
The total fat cell number and fat cell weight were determined
according to Sj6str6m et al. (1971). Serum cholesterol was
determined according to the method of Cram6r and Isaksson
(1959), and serum triglycerides according to Carlson (1959). A
glucose tolerance test was performed with 100 g glucose dissolved
in 200 ml lemon flavoured water taken orally in the morning after
overnight fasting. The subjects did not smoke that morning and
moved about leisurely. From an indwelling needle in an antecubital
vein blood samples were obtained in the supine position before and
at 30, 60, 90, and 120 min after taking glucose for the determination of blood glucose (Levin et al. 1962) plasma insulin
(Phadebas, Pharmacia, Uppsala, Sweden), and C peptide (Novo,
Copenhagen, Denmark). These tests were preceded by 3 days of
controlled diet containing 35 kcal/kg ideal body weight with the
caloric per cent of protein, fat, and carbohydrate being exactly the
same before and after the training period.
Muscle biopsies
Muscle biopsies were taken superficially before and after training
from the right vastus lateralis under local anesthesia using a
surgical technique. No complications were recorded. On each
occasion two muscle specimens were taken from the patient. One
was frozen immediately in liquid nitrogen for determination of
enzyme activities and metabolite analyses, the other was trimmed,
mounted, and frozen in isopentane (cooled by liquid nitrogen) for
histochemical analyses. Both specimens were stored at - 8 0 ~
until analysed.
Histochemical analyses
Serial transverse sections (10 p,m) were cut with a cryotome at
-21 ~
The myofibrillar ATP-ase (adenosine triphosphatase)
method was used for muscle fibre classification (Gomori 1941;
Padykula et al. 1955). The reactions were carried out at pH 9.4,
following by alkaline preincubation at pH 10.3, to classify into slow
twitch (ST, type I) and fast twitch (FT type II) fibres. The FT fibres
could be further classified into types FTa and FTb by preincubation
at pH 4.6 and 4.4 (Dubowitz et al. 1973). The mean number of
fibres counted was 614 _+ 51 (mean + SD).
Amylase-PAS-staining to visualize capillaries was used for
capillary analyses. The capillary supply was calculated according to
Andersen et al. (1977). The mean number of fibres counted for
capillaries was 104 + 23 (mean + SD). As regards the methodological error for capillary analyses, see Aniansson et al.
(1981).
K. Mandroukas et al.: Physical training in obese women
Measurements of fibre areas were made on photographs of
transverse sections, stained for DPNH-activity (Novikoff et al.
1981). An optical illumination device ("particle size analyzer",
Carl Zeiss, FRG), projecting muscle fibres as circles of varying
sizes, was used, and the total fibre area was approximated as
described by Aniansson et al. (1981). The mean number of fibres
measured for fibre areas was 226 + 10 (mean + SD).
Enzyme activity analysis
Enzyme activity determinations were performed by means of
fluorimetric techniques. The reactions catalyzed by the enzymes
under investigation were coupled to NAD-NADP-linked reactions
according to Lowry et al. (1972). The enzymes analyzed wer lactate
dehydrogenase (LDH), citrate synthase (CS), 3-hydroxyacyl-CoA-dehydrogenase (HAD), triosephosphate dehydrogenase
(TPDH), and hexokinase (HK). The assays were performed at
25~ C. The assay mixtures were somewhat modified from those
described by Bass et al. (1969). The glycogen content was
quantified according to Karlsson (1971) and the protein content
according to Lowry et al. (1951). The methodological errors
calculated from 15 duplicate determinations were: LDH 5.2%, CS
3.8%, TPDH 5.3%, protein 1.1%, HK 3.4%, and glycogen (n =
58) 4.2%.
Testing procedure for force and velocity measurements
Muscle strength of the right quadriceps was measured as the torque
during maximal static contraction and at maximal knee-extension
with constant angular velocities using an isokinetic dynamometer
(Cybex II, Lumex Inc., NY, USA) modified with a strain gauge
(Cykob, Stockholm, Sweden).
Isometric strength was measured as the torque during maximal
isometric contractions at knee extension with knee angles 60 and 90
degrees. Three tests were carried out at each angle and the highest
values were recorded.
Isokinetic strength was measured as the torque during
maximal knee extension movement with constant angular velocities, which were preset at 30, 60,120, and 180 degrees per second.
Three tests were carried out at each velocity. The highest value was
registered. Torque output and knee angles were recorded on an
x-y-recorder (Omnigraphic, Houston Instrument, USA). Isometric
endurance was measured as the time the subject could hold 50% of
the maximal isometric strength at a knee angle of 90 degrees.
Isokinetic endurance was measured as the percentage decline
in peak torque of 50 maximal isokinetic contractions at 180 degrees
per second.
To compare the pretraining values of muscle strength in obese
women with a normal population, an additional group of 14
normal-weight (60.8 _+ 6.8 kg), age-matched (36.3 _+ 9.3 years),
healthy women was tested on a Cybex dynamometer in an identical
manner to that described above.
Exercise test and determination of maximal oxygen uptake
Heart rate was measured by continuous telemetry. A Monark
(Varberg, Sweden) mechanically-braked bicycle ergometer was
used for submaximal (50 and 100 W) and maximal exercise loads.
The same submaximal exercise loads were used for pre- and
posttraining measurements of expired air volume and analysis of
O2-fraction using a Beckman OM-11.
The measuring of maximal oxygen uptake 02o2 max) started
with submaximal loads followed by stepwise increase in exercise
loads until exhaustion.
K. Mandroukas et al.: Physical training in obese women
The criterion used for maximal oxygen uptake was a levelling
of oxygen uptake despite further increase in exercise load, with
blood lactate levels > 8 mM/l. A second determination of 12o2max
was carried out on another day. Both determinations gave similar
values (_+ 3%). The Rated Perceived Exertion (RPE) (Borg 1970)
and the blood pressure were recorded at the 50- and 100-W work
loads. Blood lactate concentration was determined from fingertip
blood immediately after the maximal exercise and was analysed by
an enzymatic method (Boehringer, Mannheim, FRG).
Physical training programme
The group was trained for 3 months, three times a week. The
duration of the training session was 50min, starting with
10-15 min of warming-up exercises including walking, jogging,
and calisthenics of light intensity, including exercise with all parts
of the body.
The programme then continued with alternating heavy and
light periods. The heavy intervals were performed on a bicycle
ergometer and lasted for 4 min.
The work load was chosen individually, based on the maximal
work load performance at the test before the training. The work
during each heavy interval started with a submaximal work load.
After 3 - 4 weeks of training the work load was gradually increased.
The "light" intervals lasted 8 - 1 0 rain and consisted of walking and
calisthenics affecting mainly muscle groups other than those
utilized during the heavy intervals. The intensity of the training was
followed in each patient by telemetry. In four patients, heart rate
and oxygen uptake (by oxygen flowmeter) - Oxylog, Morgan, GB
were continuously measured during the whole training period.
The variations in oxygen uptake and heart rate during the training
intervals are shown in Fig. 1. The oxygen uptake at the heavy
intervals reached 8 0 - 8 5 % of 12o2max.
Statistics
The significance of intraindividual differences was tested using the
paired t-test. A P value of < 0.05 was considered significant.
357
Results
Three months of physical training gave no significant
changes in body weight, body fat, lean body mass, fat
cell weight, or fat cell number (Table 1). The
concentration of plasma insulin and C peptide and
blood glucose, both fasting values and values during
OGTT, did not change after training. However,
glucose values at 120 min after oral glucose load
decreased significantly after training. The extraction
of plasma insulin (calculated as the difference
between the sum of C peptide and the sum of insulin
values in nmoles/1) did not change after training
(Table 1).
Heart rate, systolic and diastolic blood pressure at
rest, and systolic blood pressure at submaximal work
load (100 W), decreased significantly after training
Table 1. Body weight and composition and metabolic variables in
obese women before and after physical training (n = 14)
Before
training
Mean
Age = (years)
Height (cm)
Body weight (kg)
Body fat (kg)
Lean body mass (kg)
Cholesterol
(mmol x 1-1)
Triglycerides
(mmol x 1-1)
Fat cell weight (gg)
Fat cell number
(x 101~
200
////_
ZZ
E
"~ 150
~Q
=
"r
100
l
LA
LJm
z - - m a x , nr~
9
m
9{ c / , '
9 >.
u
/.>./
'agl'
x
/.t~
o~
//',4,,,
100
r
o
.2~
E 50
"5
0
20
30
Time m~n
Fig. I. Heart rate (upper panel) and percentage of m a x , 1 2 o 2 (lower
panel) for one patient during different training intervals
10
Fasting glucose
(mmol x 1-I)
Fasting insulin
(gU x 1-1)
/c.
,1t
/J//
////
////,
Fasting C peptide
(nmol x 1-1)
Glucose at 120' during
OGTT (mmol x 1-1)
Insulin at 120' during
OGTT (btU x 1-1)
C peptide at 120' during
OGTT (nmol • 1-1)
Sum(Z) of glucose values
during OGGT
(mmol x 1-1)
Sum of insulin values
during OGGT
(~U x 1-1)
Sum of C peptide values
during OGTT
(nmoI x 1-1)
N C peptide - Z insulin
during OGTT in
nmol x 1-1
38.6
166.7
96.6
45.26
51.3
5.75
After
training
SEM
_+
+_
_+
+
+
•
3.10
1.47
3.91
3.35
2.9
0.30
Mean
98.5
47.87
50.6
6.03
SEM
-+
+
+
•
3.97
3.20
2.7
0.30
1.44 + 0.19
1.64 _+ 0.20
0.66 _+ 0.01
7.48 • 0.12
0.69 _+ 0.01
7.52 _+ 0.10
4.5
+ 0.1
4.5
19.9
+ 2.0
0.62 •
0.06
6.5 + 0.2
89.4 + 8.4
1.75 •
0.16
34.8
+ 2.6
414.1
_+ 29.2
7.03 _+ 0.4
4.38
•
0.6
_+ 0.2
24.3 •
2.1
0.56 •
0.03
6.0
+ 0.3*
92.8 + 6.7
1.45 •
0.11
33.3 •
2.9
444.3
• 26.0
6.88 •
0.5
4.03 + 0.7
358
K. Mandroukas et al.: Physical training in obese women
Table 2. Heart rate, systolic and diastolic blood pressure at rest and at 50-W and 100-W work loads. 12E and 12o2 at 50-W and 100-W work
loads, before and after 3 months' training
Rest
50 W
Before
training
Mean
Heart rate
(beats x rain -I)
Systolic blood pressure
(mm Hg)
Diastolic blood pressure
(mm Hg)
12E (1 X min -1)
12o2 (1 X min -1)
RPE
After
training
SEM
100 W
Before
training
After
training
Before
training
After
training
Mean
SEM
Mean
SEM
Mean
SEM
Mean
SEM
Mean
SEM
86
4
77
4***
116
4
115
4
147
5
141
4
140
4
131
4***
150
3
145
4
179
5
157
6**
87
2
80
2*
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
23.32
0.98
10
.
1.11
0.05
0.4
22.95
1.05
10
0.78
0.04
0.4
.
.
43.18
1.70
14
.
2.06
0.07
0.6
37.81
1.60
13
1.37
0.05
0.3
* P < 0.05; ** P < 0.005; *** P < 0.001
RPE denotes rated perceived exertion (Borg 1970)
Table 3. Oxygen uptake (1202)' expiratory gas volume (12E), and
plasma concentration of lactic acid at the maximal work load
before and after 3 months' training
Table 4. Fibre type distribution, fibre area, ratio of fibre area, and
relative fibre areas of the vastus lateralis muscle before and after
3 months' training. Means + SEM for 14 obese patients
Max. exercise
Before
training
Heart rate
(beats x min -1)
12E (1 X rain -1)
12o2 (1 X min -1)
Lactate (mM x 1-1)
Before
training
After
training
Mean
Mean
SEM
Mean
SEM
177
4.38
176
4.10
63.93
2.21
8.60
3.56
0.tl
0.37
78.05
2.62
9.54
2.77***
0.10"**
0.30**
* P < 0.05; ** P < 0.005; *** P < 0.001
SEM
Mean
SEM
Fibre type distribution (%)
ST
44.9
FTa
30.1
FTb
24.7
3.3
1.3
2.5
43.1
35.1
21.6
3.6
1.5"
4.0
Fibre area (~tmz x 103)
ST
FT
FTa
Fib
5.01
5.04
5.59
4.34
0.29
0.28
0.32
0.29
5.60
5.41
5.77
4.69
0.36
0.27
0.31
0.32
5.05
0.26
5.45
0.27
1.03
1.11
0.89
0.06
0.05
0.08
1.00
1.06
0.86
0.05
0.06
0.06
Mean fibre area
(~tm2 x 103)
200"
Nm
[ ] Controls
[ ] Obese before training
150"
[ ] Obese after training
After
training
Area ratio
FT/ST
FTa/ST
FTb/ST
Relative fibre area (%)
ST
FTa
Fib
43.2
33.9
26.1
3.0
1.8
4.2
43.8
37.4
18.7
3.7
2.0
3.8
100"
* P < 0.05
50-
120%
180%
O~ A90~ 0% A60~ 30~
60%
Fig. 2. Maximal and isokinetic torque values at different angular
velocities in 14 obese women and in the control group.
Means _+ SEM before and after 3 months physical training are
given
( T a b l e 1), w h i l e t h e R P E d i d n o t c h a n g e ( T a b l e 2).
Maximal oxygen uptake and blood lactate acid
c o n c e n t r a t i o n a f t e r m a x i m a l e x e r c i s e i n c r e a s e d sign i f i c a n t l y w i t h t r a i n i n g ( T a b l e 3).
I s o m e t r i c s t r e n g t h i n c r e a s e d a f t e r t r a i n i n g a t a 90 ~
knee angle. Isokinetic strength increased significantly
a t b o t h 30~ a n d 60~ a n g u l a r v e l o c i t i e s ( F i g . 2).
K. Mandroukas et al.: Physical traMng in obese women
Table 5. Capillary supply of the vastus lateralis muscle in 13 obese
patients before and after training (Means + SEM)
Before
training
Capillaries per mm2
After
training
Mean
SEM
Mean
SEM
264
12
279
14
Capillaries per fibre
1.55
0.07
1.83
0.i1"*
Capillaries around fibres
ST
FT
FTa
FTb
4.50
3.84
4.18
3.44
0.17
0.20
0.24
0.18
5.24
4.46
4.71
3.93
0.24**
0.29**
0.28*
0.31
Fibre type area per capillary
(~tm2 X 103)
ST
1.11
FT
1.29
FTa
1.34
FTb
1.26
0.05
0.07
0.07
0.09
1.05
1.21
1.20
1.21
0.05
0.05
0.05
0.05
* P < 0.05; ** P < 0.005
Table 6. Enzymatic activity and glycogen content in m. vastus
lateralis
Muscle glycogen
(mMol x g-X)
HK
(~Mol x rain -1
x g protein -1)
TPDH
(~tMol x rain -1
x g protein -I)
LDH
(~tMol x rain -1
x g protein -1)
CS
(~tMol x rain -1
x g protein -1)
HAD
(~Mol x rain -1
x g protein -1)
Before training
After training
Mean
Mean
SEM
89.81
6.i0
101.11
5.7
0.4
8.4
1,199.50
7 8 . 0 3 1,278.67
SEM
9.66
0.5***
84.94
795.92
86.36
8 3 9 . 4 2 77.54
36.98
1.87
47.01
2.88**
40.85
1.76
48.26
2.25**
** P < 0.01; *** P < 0.001
LDH = lactate dehydrogenase, TPDH = triosephospate dehydrogenase, CS = citrate synthase, HAD = 3-hydroxy-acyl-CoAdehydrogenase, HK = hexokinase
359
In c o m p a r i s o n with a normal-weight control
group, in this study the overweight w o m e n s h o w e d no
significant differences in isokinetic and isometric
maximal strength and isokinetic endurance. T h e time
during which 50% of maximal isometric contraction
was maintained a p p e a r e d to be significantly lower in
obese w o m e n , 45.5 s ( S E M ) in c o m p a r i s o n with value
of 63.7 s ( S E M ) for n o r m a l w o m e n (P < 0.05) 9
Isokinetic e n d u r a n c e (P < 0.01), but not isometric e n d u r a n c e , increased significantly after training,
the decrease in t o r q u e values for 50 contractions at
180~ being 54% ( S E M ) before and 44% (SEM) after
training 9
In spite of s o m e t e n d e n c y to increase, no
statistically significant change in fibre area was
o b s e r v e d in any of the fibre types (Table 4).
T h e p e r c e n t a g e of F T a fibres increased significantly (P < 0.05) after training. T h e n u m b e r of
capillaries a r o u n d each fibre increased mainly for the
m o r e oxidative fibre types (ST 18%, F T a 14%).
Generally, the n u m b e r of capillaries per fibre
increased significantly ( P < 0 . 0 1 )
after training 9
H o w e v e r , the part of the fibre area supplied by one
capillary did not increase significantly (Table 5).
T h e c o n c e n t r a t i o n of glycogen per gram of muscle
tissue did not change significantly after training. T h e
activities of citrate synthase (P < 0.01) and hexokinase ( P < 0.001), as well as 3 - h y d r o x y - a c y l - C o A - d e h y d r o g e n a s e ( P < 0.01), increased (Table 6), while
activities of lactate d e h y d r o g e n a s e and triosephosp h a t e d e h y d r o g e n a s e did not change.
T h e trend to decrease of the sum of glucose values
during O G T T after training was significantly correlated with the increase in the n u m b e r of capillaries
a r o u n d ST type of muscle fibres, and to the increase
of d y n a m i c e n d u r a n c e after training. T h e increase in
the n u m b e r of capillaries a r o u n d all fibres (not
shown), and particularly a r o u n d F T a type o f muscle
fibres, was significantly correlated to the increase of
Vo2 max. T h e changes (trend to increase) of the
muscle fibre area of the F T b fibres were significantly
correlated to the increase in isometric strength, and
the changes in fibre area of the F F a fibres correlated
significantly with the increase in d y n a m i c (isokinetic)
strength (Table 6).
Correlation analyses
Difference before - after physical training in
r-value
P-value
The number of capillaries in contact with ST type of muscle
fibres
Dynamic endurance
The sum of glucose values during OGTI"
0.54
0.54
0.54
< 0.05
< 0.05
< 0.05
The capillaries in contact with FTa type of muscle fibres
Vo2
0.58
< 0.05
The fibre area of Fib type of muscle fibres
Isometric strength (90~ knee angle)
0.54
< 0.05
The fibre area of FFa type of muscle fibres
Isokinetic strength (60~
0.57
< 0.05
max
360
Discussion
As previously reported in severely obese subjects
(Bj6rntorp et al. 1973b; Krotkiewski et al. 1979,
1983c, 1983e), long-term physical training without
restriction of food intake resulted neither in changes
in body weight and composition nor in changes in fat
cell weight or number.
When maximal oxygen uptake was analyzed at
the start of the experimental period, obese women
showed values comparable with those of healthy
non-obese women (Sullivan 1976; Sullivan e t a ! .
1981). In obese patients, physical training resulted in
a normal cardiovascular adaptation with a 20%
increase in maximal oxygen uptake, comparable to
previously reported results in obese persons (Bj6rntorp et al. 1970; 1973a, 1973b).
Overweight persons often have elevated lean
body mass (Bj6rntorp et al. 1970; 1973a, 1973b).
They are compelled to develop some extra force to
mobilize the weight- supporting muscles in order to
compensate their overweight. These factors may
imply differences in the recruitment pattern and
composition of muscle fibres. The obese women were
normoglycemic and only slightly hyper-insulinemic
before training. In a similar group of obese normoglycemic women we could not find any indications of
insulin resistance and intensitivity in terms of insulin
binding, insulin effects on glucose incorporation to
triglycerides and on lipolysis (L6nnroth et al. 1983;
Krotkiewski et al. 1983c, 1983d) and in terms of
glucose disposal during euglycemic insulin clamp
(Krotkiewski et al. 1983c, 1983d). The decrease in the
120-rain glucose value is also in accordance with
repeated observations on the improvement of glucose
tolerance (Krotkiewski 1983a) and glucose disposal
during euglycemic insulin clamp (Krotkiewski et al.
1983c, 1983d) after training in obese normoglycemic
women. The slight improvement noted at 120 rain
during OGTT is also in harmony with the increased
activity of hexokinase.
In comparison with morphologic data reported
for 54 healthy normal weight women by Nygaard
(1981), the obese group generally showed large
cross-sectional areas of muscle fibre. Furthermore,
both the relative percentage distribution and the
cross-sectional area of FTb fibres seem to be
exceptionally high in obese persons. Physical training
increased the relative proportion of FTa fibres, while
a trend to decrease could be observed with respect to
FTb fibres (Table 4) as expected from an endurance
training programme in relatively untrained individuals (Saltin et al. 1977).
In comparison with a population of normal-weight sedentary women described by Nygaard
(1981), obese women have a somewhat higher
K. Mandroukas et al.: Physical training in obese women
number of capillaries around the various types of
muscle fibres. The number of capillaries around
different types of muscle fibres increased after
training. As a similar increase took place concomitantly with respect to the fibre area, the proportion
of cross-sectional area supplied by one capillary did
not change significantly. This is in contrast with the
results described by Aniansson et al. (1981) in older
men and women, and in healthy men of normal
weight (Andersen 1977), where the decrease in fibre
area per capillary was treated as evidence of
improved diffusion distance.
It has been found that body weight correlates
positively with maximum strength and negatively
with muscular endurance (Elbel 1949; Joyes 1947;
Josenhans 1962). More recently, however, a negative
relationship between body weight and muscular
endurance has been reported, and it is suggested that
it is caused by the higher deep muscle temperature
(Petrofsky et al. 1975) due to insulation by the
subcutaneous fat layer around a limb. In the present
study, isometric endurance also showed reduced
values compared with the controls. Both training and
weight reduction through a low caloric diet (Krotkiewski et al., unpubl, results) appeared to improve
the reduced isometric endurance in obese women.
In comparison with normal weight women, the
overweight participants showed similar dynamic and
isometric strength measured on an isokinetic dynamometer at different angular velocities and at
different knee angles. The positive correlation
between the improvement of glucose tolerance and
the increased capillarization of muscle tissue has been
reported previously (Krotkiewski et al. 1983e). The
significant correlation between the changes in glucose
concentrations and the increase in dynamic strength
(Table 6) might reflect the importance of better
substrate availability for the working muscle.
In conclusion, obese women show a higher
percentage and area of FTb fibres in comparison with
data available in the literature for normal weight
women. Physical training results in increased enzymatic activities and microvascular proliferation in
muscles, but the increased number of capillaries is not
sufficient to diminish the diffusion distance because
of concimitant increase in fibre areas. The relative
proportion of endurance and strength components in
the training programme can, however, be responsible
for such variations in training effects. The central and
peripheral adaptations of physical training in obesity
seem to be generally comparable to those observed in
non-obese women.
Acknowledgements. The study was supported by grants from Greta
and Einar Asker's Foundation 1981 and 1982; Nordiska Samfundets Stiftelse f6r Vetenskaplig Forskning och Djurf6rs6k; the Sport
K. Mandroukas et al.: Physical trai~aing in obese women
Research Council 48/81; and the Swedish Medical Research
Council (Project 03888).
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Accepted January 18, 1984