379
NORMATIVE ASSESSMENT TECHNIQUE
FOR BENCH PRESS AND LEG EXTENSION STRENGTH
IN COLLEGE FEMALES ON THE UNIVERSAL GYM
THESIS
Presented to the Graduate Council of the
North Texas State University in Partial
Fulfillment of the Requirements
For the Degree of
MASTER OF SCIENCE
by
Jean Gibson
Denton, Texas
August, 1983
- --- --
1984
DOROTHY JEAN GIBSON
All Rights Reserved
Gibson, D. Jean, Normative Assessment Technique for
Bench Press and Leg Extension Strength in College Females
on the Universal G Master of Science (Physical Edu-
cation), August, 1983, 44 pp., 6 tables, bibliography,
37 titles.
This study was to develop normative data of isotonic
muscular strength in college females using the Spartacus
model Universal Gym bench press and leg extension and to
control for the influence of body weight. Two hundred and
two college age females enrolled in weight training and
conditioning classes used the Universal Gym for twelve weeks.
Subjects were tested for maximum strength on 2 exercises and
their percent body fat was calculated. Pearson-product
moment correlations between lean body we ight , body weight
and the bench press test and the leg extension test were
correlated. After statistically controlling for the effects
of body weight, percentile ranks were calculated for both
tests.
y .. ,t1'.rr+n4 r: ,. .+. .': . :- :.. .,, .:v+--. >. ... : V/w kl t ,. _. .-... :,i -.. ;:, ::.. _. .x.,;. iwYiH ':"- _,- -.. .:. aus, :.. -'
TABLE OF CONTENTS
Page
LIST OF TABLES ........-.-........... iv
Chapter
I. INTRODUCTION . . . . . - - - - - . -"-"-"-"-"
II. REVIEW OF LITERATURE.............. 7
Nature of StrengthMeasurement of StrengthStructure of StrengthRelationship of Body Weight to StrengthStrength Research on WomenSummary
III. PROCEDURES . ................ 20
Selection of the SubjectsTesting EquipmentTest ProceduresPilot StudyStatistical Analysis
IV. RESULTS.. .......-.-.......... 25
Descriptive StatisticsRelationship Between the Anthropometric
Measures and the Strength TestsRegression Analysis and NormsTable III-IV Percentile Norms for Maximum
Bench Press Strength (lRM) atDifferent Body Weights
Table V-VI Percentile Norms for MaximumLeg Extension Strength (IRM) atDifferent Body Weights
V. DISCUSSION . - - -33
Utilizing the NormsSummary of the Present StudyConclusionsRecommendations
REFERENCES. .......-.-........ .......... 39
APPENDIX...........-.-.-.-.-.-..-. . . . ..- 43
III
r .4
LIST OF TABLES
Table Page
1. Descriptive Statistics ............... 25
2. Correlations Between the AnthropometricMeasures and the Strength Tests . .. . . 26
3. Percentile Norms for Maximum Bench PressStrength (lRM) at Different BodyWeights....... . . . . . . ......... 29
4. Percentile Norms for Maximum Bench PressStrength (1RM) at Different BodyWeights .................. ".-.. -.-.-.30
5. Percentile Norms for Maximum Leg ExtensionStrength (lRM) at Different BodyWeights......... ............... . 31
6. Percentile Norms for Maximum Leg ExtensionStrength (1RM) at Different BodyWeights... . .. . . ............ 32
iv
CHAPTER I
INTRODUCTION
Strength, the ability to apply or resist force, is
necessary to perform everyday tasks such as standing,
walking, opening a window, and carrying groceries.
Strength is also essential to the athlete who wishes to
perform at his/her best in athletic events from cycling,
swimming, tennis, and golf to those events of weight
lifting, shot putting, discus and hammer throwing (Lamb,
1978). To gain strength, many individuals train with
weights, which provide the necessary principles of inten-
sity and overload. More and more women are desiring to
physically exert themselves. Some wish to competitively
lift weights or to enhance performance in a particular
sport or to rehabilitate an injured body part. Predomi-
nantly, women desire to strength-train to add quality to
their lives, look and feel better, and consequently raise
their self-image (Westcott, 1982).
A review of the literature revealed that the majority
of strength studies performed on women described the
physical characteristics of women but did not develop
normative data on women's strength characteristics, which
1
2
the physical educator and strength trainer need. Recent
studies by Hosler, Morrow, and Jackson (1978) established
normative data for college women volleyball players using
the Cybex Power Bench and Power Leg Press. Percentile rank
norms for adult women on the Universal Gym were developed
at Arizona State University. Both of the aforementioned
studies derived their norms after statistically controlling
the effects of body weight (Baumgartner & Jackson, 1982).
A recent study by Patton, Jackson, and Watkins (1981)
established normative data for previously validated
measures of isotonic muscular strength in collegemales on
the Universal Gym while controlling for individual differ-
ences in body weight. A similar study is needed to develop
strength norms for women which control for body weight.
Strength can be assessed isometrically against a fixed
resistance, isotonically against a moveable object, or iso-
kinetically, in which the resistance is controlled at a
fixed speed. A large number of educational and other
institutions utilize the Universal Gym equipment as an
effective isotonic strength development apparatus which is
safe, convenient, and relatively inexpensive. Thus, the
development of strength norms for women which control for
individual differences in body weight using the Universal
Gym is valuable.
3
PURPOSE OF THE STUDY
The purpose of the study was to develop norms of
isotonic muscular strength in college females using the
Universal Gym and to control for the influence of body
weight. Past studies have substantiated that strength is
significantly correlated with body weight (Baumgartner &
Jackson, 1982; Berger, 1982; Clarke, 1945; Fleishman,
1964; Jackson & .Frankiewicz, 1975; and Wilmore, 1977).
Several researchers have indicated that body weight should
be statistically controlled when individual differences in
strength are to be assessed (Jackson, Watkins, & Patton,
1980).
Numerous investigators have shown that strength is a
multifaceted construct comprised of types of contractions
and body segments (Fleishman, 1964; Jackson & Frankiewicz,
1975; Liba, 1967). For example, in a recent study using
the Universal Gym, Jackson, Watkins, and Patton (1980)
identified that the bench press represented a valid upper
extremity isotonic strength measurement and that the leg
extension represented a valid lower extremity isotonic
strength measurement in college men.
To achieve the purpose of this study, isotonic
muscular strength measurements were assessed by obtaining
1 RMs (1 repetition maximum) on the bench press and leg
extension following the procedures employed by Berger
4
(1962) and supported by Jackson, Watkins, and Patton
(1980). Percent body fat was determined using skinfold
measurements, following steps recommended by Behnke and
Wilmore (1974) and Pollock and Jackson (1976). This
procedure allowed the delineation of the contributions of
body weight and lean body weight to individual differences
in strength among women and the development of the most
valid norms. This could prove useful since women have
higher levels of fat than men which would not contribute
to strength.
DELIMITATIONS
The study was delimited to college-age females being
tested for isotonic strength on the Spartacus model
Universal Gym bench press and leg extension apparati.
LIMITATIONS
The study was subjected to the following limitations.
1. Accurate 1 RM's on the bench press were restricted to
five pound increments.
2. Accurate 1 RM's on the leg extension were restricted
to 5 pound increments.
3. The subjects tested were enrolled in various condi-
tioning and weight training classes and followed
different conditioning procedures.
r
5
DEFINITIONS
1. 1 RM - repetition maximum - the maximum amount of
weight that can be lifted once through a full range of
motion; it is the criterion measure of maximum strength
in isotonic movements. (Berger, 1962)
2. Lean Body Weight (LBW) - body weight - the weight of
the body that is not fat, e.g., bone, muscle, skin,
etc. (Weinberg, Caldwell, Cornelius, Jackson, &
Smith, 1982)
3. Fat Body Weight (FBW) - absolute amount of body fat.
(Weinberg, et al., 1982)
4. Percent Body Fat (% body fat) - denotes percentage of
total body weight that is fat. (Weinberg, et al.,
1982)
5. Body Weight - lean body weight plus fat body weight.
(Weinberg, et al., 1982)
6. Bench Press - station on the Universal Gym in which
an individual maintains a supine position on the bench
and attempts to lift weights. Principal muscle
contractors are the pectoralis major and
triceps. (Weinberg, et al., 1982)
7. Leg Extension - station on the Spartacus model
Universal Gym in which an individual maintains a
seated position on the bench with his feet placed
on the lower pads of the leg machine. The subject
6
will attempt to extend her legs until they form a
straight line. Principal muscle contractors are the
rectus femoris, and vastus intermedius, lateralis,
and medialis (quadriceps). (Weinberg, et al., 1982)
CHAPTER II
REVIEW OF LITERATURE
In order to achieve the purpose of this study, namely,
establishing valid strength norms for women using the
Universal Gym, a review of related literature was conducted.
The areas covered were the nature of strength and the effect
that body weight has on it, and the concepts behind past
attempts in developing normative data on strength in women.
NATURE OF STRENGTH
Wilmore (1977) defines strength as the ability to apply
or resist force. It can be divided into two categories:
static and dynamic strength. Static strength is force
applied against a fixed resistance in which there is no
change in the angle of a joint or a movement in the
resistance. An example of a static or isometric
contraction would be to push against a wall. Dynamic
strength involves movement of the muscles, joints, and
the resistance, such as lifting a barbell. Dynamic
strength can be applied isotonically and isokinetically.
In isotonic movements, the resistance is constant
throughout the full range of motion. For example, when an
individual curls 130 pounds, the forearm flexors can exert
7
8
a force greater than 130 pounds, yet due to the mechanics
of the elbow joint, maximal contraction may only be exerted
at 30 and 150 degrees joint angles. Isokinetic movements
involve maximal contraction of the muscle group at a
constant speed through the full range of motion which is
accomplished by varying the resistance. The resistance is
controlled at fixed speed whatever the amount of strength
applied.
Static and dynamic movements can involve concentric
and eccentric contractions. Dynamic concentric
contractions involve muscle shortening while eccentric
contractions refer to muscle lengthening.. With a biceps
curl, lifting the weight with the arms fully extended to
a position of complete forearm flexion would be an example
of a dynamic concentric contraction. Lowering the weight
from the fully flexed position to the fully extended
position involves a dynamic eccentric contractions. A
static concentric contraction where there is no percept-
ible movement can be illustrated by a push or pull on an
immovable resistance or object. A static eccentric
contraction would be illustrated by holding a weight in
a fixed position (Wilmore, 1977).
MEASUREMENT OF STRENGTH
Strength can be assessed one of four ways: 1) tensi-
ometry, 2) dynamometry, 3) repetition maximum or 1 RM, and
9
4) computer-assisted force and work output determinations.
(McArdle, Katch, and Katch, 1981). Cable tensiometry
measures the pulling force of a muscle during a static or
isometric contractions. For example, to measure the
muscular force exerted during a knee extension, a band is
placed around a subject's lower leg which is attached to
a cable. As the subject begins to extend his leg, a force
is applied to the cable. As the force on the cable
increases, the riser, over which the cable passes, is
depressed which deflects the pointer and indicates a
strength score.
Dynamometers (e.g. hand-grip and back-lift) measure
static strength and operate on the principle of compression.
When a force is applied to the dynamometer, a steel spring
is compressed which moves a pointer and subsequently
indicates a strength score (McArdle, et al., 1981).
A dynamic method of assessing strength uses the one-
repetition maximum or 1 RM method. This refers to the
maximum amount of weight that can be lifted one time.
Berger's (1962) standardization of the 1 RM utilizes a
warm-up procedure and graded increases in resistance until
a failing attempt is observed. As an example, to assess
a subject's 1 RM on the bench press, a suitable starting
weight is selected close to but below the subject's maximum
lifting capacity. If one repetition is completed with full
extension of the arms, the subject would rest three to five
10
minutes at which time he would attempt to lift a load
increased by 10 pounds. This procedure would continue
until the subject failed to completely raise the load.
After three to five minutes of rest, the subject would
attempt to raise the load increased by five pounds. This
procedure is followed until the maximum is obtained
(Berger, 1962).
Modern technology provides the fourth way to measure
muscular strength, namely, the isokinetic dynamometer which
contains a speed-controlling device. Once the constant
speed is attained, the isokinetic loading mechanism
provides a counterforce equal to the muscle-generated
force. Consequently, maximum force can be applied during
all phases of the movement at a constant velocity. A load
cell inside the dynamometer monitors the level of applied
force and counteracting resistance and subsequently relays
the information to a recording device (McArdle, et al.,
1981). Thus, muscular strength can be assessed with iso-
metric, isotonic, and isokinetic contractions.
STRUCTURE OF STRENGTH
Past research has identified underlying factors of
muscular strength as measured by isometric, isotonic, and
muscular endurance exercises (Fleishman, 1961; Jackson &
Frankiewicz, 1975; Liba, 1967).
11
A review of related literature revealed that numerous
investigators have identified strength as a multifaceted
construct. Fleishman demonstrated that three factors are
associated with strength - "static strength", force exerted
against an immoveable object such as a dynamometer, "dynamic
strength", as measured by events such as pull-ups, rope
climb, and dips, and "explosive strength", as measured by
the standing broad jump, vertical jump, or medicine ball put
and that strength is related to body segments during iso-
metric contractions (Fleishman, 1964).
Liba's findings contradicted the three factor strength
model proposed by Fleishman. Liba reported nine underlying
factors of muscular strength that are related to body
segments and type of muscular contraction. An alpha factor
analysis identified two factors associated with body
projection, one factor identified by object-projection; one
factor represented by supporting the body weight; one factor
identified by two lunge items; and three factors represented
by five dynamometric strength variables. Liba delineated
that push and pull movements of the arm involve the muscles
of the upper trunk and are grouped with the trunk pull
distinct from hand and knee extension (Liba, 1966).
A recent Jackson, Watkins, and Patton (1980) study
identified the underlying structure of isotonic strength
in men as exhibited on the Universal Gym. Eighty-eight
college male subjects were tested on twelve selected
12
exercises using the Universal Gym: military press, bench
press, "lat" pull down, sit-ups, upright row, bent knee
ups, upper leg press, lower leg press, leg extension, leg
curl, lateral flexion, and hyperextension. One RMs were
assessed on each exercise with some procedural modifi-
cations being employed for the hyperextension, sit-ups,
bent knee up, lower leg press, and upper leg press lifts.
The raw data were analyzed with alpha and canonical factor
analyses. To control for the variance associated with
weight and height, second order partial correlations
between the isotonic strength measures were calculated.
The investigators postulated that statistical control of
the anthropometric differences of height and weight would
produce a clearer interpretation of the underlying factors
of strength. The correlations of the twelve strength
measures ranged from .091 to .872. The second order
partial correlations ranged from .044 to .841. Both alpha
and canonical factor analyses identified three factors:
Factor I related to upper extremity and trunk contractions,
Factor II related to lower extremity contractions, and
Factor III related to trunk and upper extremity
contractions. The study revealed that the bench press and
military press were the most valid upper extremity isotonic
strength measures for Factor I, and that the upper leg
press and lower leg press represented the most valid iso-
tonic strength measures for Factor II, and that lateral
,. ,,.. .r ,.u,;.M. .,, . , ,
13
flexion best represented Factor III. The leg extension
and leg flexion also possessed acceptable validity
coefficient. Factor III was not clearly delineated as a
trunk strength factor because of upper extremity
involvement (.Jackson, Watkins, and Patton, 1980).
RELATIONSHIP OF BODY WEIGHT TO STRENGTH
Many investigators agree that since strength is a
physical fitness component, it should be related to each
individual and it should be measured in relation to the
individual's body weight (Johnson & Nelson, 1979). Past
research has confirmed that body weight is moderately
correlated with strength and subsequently influences
accurate assessments of strength (Baumgartner & Jackson,
1982; Berger, 1962; Jackson & Frankiewicz, 1975; Jackson,
Watkins, and Patton, 1980; Johnson and Nelson, 1979; and
Mood, 1980).
Johnson and Nelson (1979) and Mood (1980) recommend
assessing an individual's relative strength by dividing
his body weight into the amount of weight he lifted in 1
execution to create a ratio. This ratio aLlows for
comparison between individuals of differing body weight
but does not statistically control for the effects of body
weight on strength.
In a study designed to clarify the factor structure of
muscular strength, Jackson and Frankiewicz (1975) hypoth-
esized that without controlling for the influence of body
14
weight, the delineation of the underlying factors of
strength would be unclear. To control for effect of body
weight, a residual score procedure was employed.
In a similar study, Jackson, et al. (1980) sought to
isolate the underlying factor structure of isotonic
strength in college men using the Universal Gym. Alpha
and canonical factor analyses were applied to the twelve
strength tests. When the raw data of the strength measures
were analyzed, a clear factor structure was not identified.
But when the variance associated with weight was eliminated
from the strength measures, three robust factors emerged
from the factor analyses.
Baumgartner and Jackson utilized the following
regression equations to assess women's strength (1 RM) on
the bench press:
Y' (bench press) = .355 (body weight) + 19.601
SE = 12.4
(Baumgartner & Jackson, 1982).
In conclusion, the preceding data suggested that iso-
tonic strength measurements could be validly obtained by
using upper and lower extremity strength measurements if
the effects of body weight was controlled.
STRENGTH RESEARCH ON WOMEN
Standardizing and simplifying the measurement of iso-
tonic strength has been a long-time goal of many investi-
15
gators. Establishing norms for isotonic exercises is
important because an isotonic muscular contraction is a
principal training method for the strength training physical
educator and teacher (Jackson, et al., 1981).
However, a review of literature revealed few studies
establishing strength norms for women. One of the earliest
investigators to develop standardized testing procedures
and norms for physical condition, athletic performance,
and muscular strength was Dr. Frederick Rand Rogers (Clarke,
1945). Rogers' PFI (physical fitness index) battery
comprises seven test items that stress most of the large
muscles of the body: forearms, upper arms, shoulder
girdles, back, and legs. Rogers' test of seven elements is
a reduction from the ten item test developed by Sargent.
Rogers' norm tables combine such variables as sex, age, and
weight for every two pounds and each half-year increase in
age. Two scores, the Strength Index (SI) and the Physical
Fitness Index (PFI) are utilized. The Strength Index is a
composite score obtained from six strength tests (arm
strength, composed of pull-ups and push-ups, leg strength,
back strength, left-grip strength and right-grip strength)
plus lung capacity. Its purpose is to measure general
athletic ability, not physical fitness (Clarke, 1945).
Rogers hypothesized that an individual with a high strength
index should have a higher athletic ability than an
individual with a low strength index. To obtain the PFI the
16
following formula is used:
Achieved SIPFI = NrSI x 100
Norm SI
For example, a twenty-two year old woman who weighs 144
pounds has an obtained Strength Index of 1905; her norm
Strength is 1814. Thus, 1905 divided by 1814, times 100,
equals a PFI of 105. A PFI of 100 is considered average
(Mathews, 1978).
Co .ger and Macnab (1967) compared the strength and
body composition of forty participants and 40 nonpartici-
pants in Women's Intercollegiate athletic program. The
40 participants were comprised of women involved in
swimming, basketball, volleyball, and gymnastics teams at
the University of Alberta. The nonparticipants were
enrolled in required physical education classes. The cable
tensiometer was used for all strength tests and individual
measures of shoulder flexion, shoulder extension, shoulder
horizontal flexion, forearm flexion and extension, ankle
flexion, hip flexion and extension, and knee extension.
Total strength was recorded as the total of nine strength
measures. Clarke' s technique for measuring strength was
the procedure followed and all measures were recorded in
pounds. As was hypothesized, the participants were found
to be significantly stronger than the nonparticipants in
all strength measures. The participants had a total
strength measure of 743.8 pounds and the nonparticipants
17
had a total of 606.0 pounds. The correlation between
weight and the toral strength was .40 and .31 for the
participants and nonparticipants respectively. It was
identified that body weight and lean body mass showed a
significant difference whereas percent body fat did not
(Conger & Macnab, 1967).
Zuti and Corbin (1977) developed normative data for
leg extension strength on 1533 freshman females without
accounting for height or weight. Normative data were
collected for right-hand grip strength and left-hand grip
strength, upper back strength, and leg extension strength
following Clarke procedures for dynamometer measures and
using isometric contractions (Zuti & Corbin, 1977).
Johnson and Nelson established ratio strength norms
for college women on the free weights at Corpus Christi
State University in 1976. The raw scores were calculated
by dividing an individual's body weight into the additional
weight lifted. The norms were based on the scores of 65
college women. The women were retested after nine weeks of
training to assess increases in strength. An example of
a score follows: if a woman who weighs 144 pounds can bench
press 75 pounds, then the ratio score obtained would equal
.51, which would fall into the intermediate performance
level after nine weeks of training (Johnson & Nelson, 1979).
Hosler, Morrow, and Jackson (1978) developed speed,
strength, and anthropometric norms of college women
18
volleyball players. Strength was measured with the Cybex
Power Bench and Power Leg Press with the score represented
as a maximum force exerted through a range of motion.
Following Behnke and Wilmore (1974) procedures, measures
for stature, bicromial diameter, and bi-iliac diameter were
taken using a GPM Swiss-made sliding caliper. Skinfold
measures were taken at the tricep, suprailiac, and thigh
using the Lange calipers following the procedures of Behnke
and Wilmore (1974). The thigh and suprailiac skinfolds were
weighted by a regression equation and were used to estimate
body density and subsequently, percent body fat. The norms
developed for strength on the bench press and leg press
accounted for body weight (Hosler, Morrow, and Jackson,
1978).
Finally, percentile rank norms for adult women on the
Universal Gym bench press were developed at Arizona State
University. One RM's were assessed and normative data was
presented for various body weights (Baumgartner & Jackson,
1982).
In conclusion, the data suggested that isotonic
strength measurements can be validly obtained by using
upper and lower extremity strength assessments if the
effects of body weights are controlled. Furthermore, a
large number of educational and other institutions
recognize the Universal Gym as an effective development
apparatus that is safe, convenient, space and time
19
efficient, and most of all, relatively inexpensive (Westcott,
1982). Consequently, a study designed to establish strength
norms for women using the Universal Gym was warranted.
CHAPTER III
PROCEDURES
Selection of the Subjects
Two hundred and two volunteering college age females
enrolled in weight training and conditioning classes at
North Texas State University, formed the sample in the study.
The weight training and conditioning classes selected for
the study were all using the Universal Gym apparatus for
the development of strength and all subjects had completed
12 weeks of conditioning at the time of data collection.
(See Appendix A - Informed Consent form).
Testing Equipment
The equipment used in the present study to assess
strength was the Spartacus model Universal Gym bench press
and leg extension machines. A Harpenden skinfold caliper
was used to assess subcutaneous fat.
Test Procedures
To assess the one repetition maximum (1 RM) on the
bench press and leg extension, Berger' s (1962) 1 RM
procedure was followed. After a standardized warm-up
period, which included 10 wall push-ups and 10 deep knee
20
21
bends, the subject lay supine on the bench, hands grasping
the bar, shoulder width apart, palms facing upward. A
suitable starting weight was selected close to but below the
subject's maximum lifting capacity. If one repetition was
completed with full extension of the arms, the subjects
rested three to five minutes, at which time the load was
increased by five pounds. This procedure continued until
the subject failed to completely raise the load.
To assess the 1 RM on the leg extension, the subject
sat down on the bench, placed her feet under the lower pads
of the leg machine, and held onto the bench, keeping her
back as straight as possible. A suitable starting weight
was selected close to but below the subject's maximum
lifting capacity by asking the subject what weight she knew
she could lift. If one repetition was completed with full
extension of the legs, the subject rested three to five
minutes at which time she attempted to lift a load 10 pounds
heavier. This procedure continued until the subject failed
to completely raise the load. The last successful lift was
as the subject's 1 RM. The aforementioned procedures were
supported by Jackson, et al. (1980).
To predict percent body fat, an individual's body
composition was assessed. Body composition consists of bone,
body fat, and lean body weight and is determined by assessing
body density.
22
Densitybody =_we:ightbody volumebody
Relative fat = 4 9 5/Densitybody - 450
(Siri, 1956). Laboratory methods of hydrostatic weighing,
radiographic analysis, potassium 40, and total body watet
determination are valid measurement techniques but are not
practical for mass or field testing. Thus, anthropometric
measurements including skinfold measurements have been used
to estimate body composition (Jackson & Pollock, 1976).
Behnke and Wilmore (1974) derived generalized equations that
allow the estimation of body composition and lean body weight
in young men and women. Also, Pollock and Jackson (1976)
followed suit by deriving multiple regression equations for
predicting body weight, fat, and lean body weight in men and
women. These equations provide the researcher with
techniques that can be applied to populations of different
ages and body composition, yet they are time consuming. To
decrease the amount of time spent calculating, Baun, Baun,
and Raven (1981) derived a nomogram based on Jackson and
Pollock's (1976) generalized equations for age and sum of
three skinfold values to determine percent body fat.
This study utilized Behnke and Wilmore (1974) procedures
of assessing skinfold measurements and Baun, Baun, and
Raven's (1981) nomogram to determine percent body fat.
The subject's weight was recorded, then using a
Harpenden skinfold caliper, skinfold measurements were taken
23
from the triceps, suprailium, and thigh. The mean of three
trials at each site were used as the final skinfold
measurement.
Pilot Study
To determine the objectivity and reliability of the
experimenter's testing procedures, a pilot study was
conducted. Subjects' (N=ll) bench press, leg press, percent
body fats were determined using the previously described
procedures. Reliability was established for the bench press
and leg extension measurements with correlations of .99 and
.92 between the trials, respectively. Also, no significant
differences were observed between trials. Reliability and
objectivity was established for percent fat values. A
correlation of .98 was calculated between the experimenter's
percent fat values and an experienced laboratory technician' s
values. No significant differences were found between the
sets of percent fat values. Also, the internal consistency
of the experimenter's skinfold assessments averaged .95.
Statistical Analysis
Pearson-product moment correlations between lean body
weight, body weight, and the bench press test and the leg
extension test were calculated. If the correlations were
statistically and physiologically meaningful, bivariate
regression equations were to be developed with body weight
24
predicting the strength tests. The equations followed:
Y1 = a1 + b1 (body weight)
Y2 = a2 + b2 (body weight)
where Y1 predicted bench press
Y2= predicted leg extension
(Glass & Stanley, 1970).
In order to calculate an individual's score with the
influence of body weight held constant, the residual scores
were determined with the following equations:
Bench press -Y1 = Yb-l
Leg Extension - Y2 Y1-2
where Yb-l = bench press with body weight held constant
Y 12 = leg extension with body weight held constant
(Baumgartner & Jackson, 1982). Finally, percentile rank
norms were developed for raw score 1 RM measurements, 1 RM' s
controlling for body weight.
CHAPTER IV
RESULTS
This chapter presents the descriptive statistics of
the study, the correlations showing the relationship
between the anthropometric measures and the strength tests,
and the generated norms and their applied use. The
descriptive statistics, including mean, standard deviation,
and standard error, are presented in Table I below.
Table I
Descriptive Statistics of the Variables Measures
Variable
Age
Weight
Percent body fat
Fat body weight
Lean body weight
Bench press
Leg extension
19.683
127.584
24.7
32.041
95.543
80.173
94.703
lbs
lbs
lbs
lbs
lbs
lbs
S .D.
I.512
17.899
5.6.
10.871
11.236
18.813
29.53
S.E.
0.106
1.259
.39
0.751
0.791
1. 183
2.078
25
26
Relationship between the anthropometric measures and the
strength tests
Pearson-product moment correlations between lean body
weight, body weight and the bench press test and the leg
extension test are presented in Table II.
Table II
Correlations Between the AnthropometricMeasures and the Strength Tests
Bench Press Leg Extension
Body weight .441 .458
Fat weight .095 .148
Lean body weight .571 .550
After examining the correlations, it was concluded that
even though lean body weight has a statistically higher
correlation to the strength measures than body weight, the
difference is not of sufficient magnitude to cause the
practitioner to become concerned with lean weight and fat
weight assessment. Also, the use of body weight to predict
strength is a more practical method for a teacher to use
because assessing lean body weight requires more time in
taking skinfold measurements.
The results of this study support past research
(Baumgartner & Jackson, 1982; Berger, 1982; Clarke, 1945;
Fleishman, 1964; Jackson & Frankiewicz, 1975; Wilmore,
27
1977 by confirming that body weight is related to strength
performance. In this study, a positive correlation was
found between body weight and the leg extension scores
(.458) and between body weight and the bench press scores
(.441). The mean percent body fat was calculated to be
24.7% which is in agreement with past research's
measurements of the average percent body fat in women
(Williams, 1983). The calculated mean body composition of
24.7% is evidence that the present study's sample is
typical of the average female population.
Regression Analysis and Norms
A simple linear regression analysis was used to
determine the least square equations with body weight
predicting the leg extension and bench press tests. The
equations follow:
Equation 1 - predicted bench press =
(.41035) body weight + 27.81903
Equation 2 - predicted leg extension
(.80115) body weight + 7.1096
In order to obtain a strength measure free of the influence
of body weight, a residual score method was used
(Baumgartner & Jackson, 1982). The third equation
demonstrates this method:
Equation 3 - y - y1 = y residual
where y is the actual strength score, y is the strength
28
score predicted from the individual's body weight and y
residual is the strength score which is uncorrelated with
body weight.
Percentile ranks were calculated on the y residual
scores for both tests. Predicted strength test scores were
calculated for individual body weights each 5 lbs from 85
lbs to 200 lbs. Appropriate corresponding residual scores
to percentile ranks 95% to 5% were added to the predicted
values to establish a norm referenced strength score that
holder body weight constant. Tables 3 - 6 present the results
of this procedure. For example, in examining Table IV, on
page 30, an individual who weighs 130 lbs and can bench
press 90 lbs would have a percentile rank of 75. The same
individual, if she lifted 130 lbs on the leg extension
machine, would have a percentile rank of 90.
29
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CHAPTER V
DISCUSSION
Utilizing the Norms
The reader should remember that the present study was
delimited to the Spartacus model Universal Gym bench press
and leg extension apparati. Since strength is a component
of physical fitness, many investigators contend that it
should be related to each individual' body weight. Some
researchers calculate a strength index by dividing an
individual's body weight into the additional weight lifted
(Johnson & Nelson, 1979) The problem with this technique
is that researchers have shown that body weight is only
moderately correlated with strength and thus affects
strength performance. The present study provides a more
valid method of assessing an individual's strength
performance by statistically controlling for the effect of
body weight on strength. Both teacher and strength trainer
can use these norms to evaluate performance and gain
immediate feedback which can serve as a motivation in itself.
For example, in evaluating the strength performance of a
student who weighs 120 1bs and can bench press 80 lbs, a
teacher can determine that the student ranks at the 60th
percentile and subsequently ascribe a grade. A student, on
33
34
the other hand, can see her improvement by determining her
starting percentile rank and her last percentile rank after
a training session of 6 weeks or more. AAHPERD's newly
developed health related fitness test recommends that when
using norm reference standards, the 25th and 50th percentiles
should be used as criterion to measure a student's
performance. In other words, the 25th percentile in each
test would be considered the minimal acceptable score and
students ranking below this level should be provided with
remedial training. AAHPERD also recommends that all
students should strive to attain the 50th percentile on all
test items. AAHPERD's method of interpreting norms could be
applied to this study's norms (Blair, Falls, & Pate, 1983).
Summary of the Present Study
In recent years, strength training has become common
practice for many individuals, including women. More and
more women desire to strength train to add quality to their
lives and consequently look and feel better, yet the
normative data has not been available to the strength
trainer which could give important feedback and serve as a
motivator. The development of normative data of isotonic
strength in college females is a desirable goal. Estab-
lishing norms for isotonic strength is important because
isotonic muscular contractions are a principal training
method for the strength training physical educator and
teacher (Jackson, et al., 1981).
35
A review of literature revealed that the majority of
the studies performed on women described the physical
characteristics but did not develop the normative data on
women's strength characteristics which the physical educator
and strength trainer need. Roger's PFI (physical fitness
index) norm tables combined the variables of sex, age, and
weight for every 2 lbs and each half-year increase in age
and used a Strength Index and physical fitness index as a
method to measure general athletic ability, not physical
fitness (Clarke, 1945). Conger and McNab (1967) compared
strength and body composition of 40 participants and 40
nonparticipants in Women's Intercollegiate Athletic Program.
A cable tensiometer was used to measure 9 strength tests.
Total strength was recorded as the total of the nine
strength measures. As was hypothesized, the participants
were found to be significantly stronger than the nonpartic-
ipants in allstrength measures. The correlation between
weight and the total strength was .40 and .31 for the
participants and nonparticipants, respectively.
Zuti and Corbin (1977) developed normative data for
leg extension on 1533 freshman women without accounting
for height or weight. Normative data were collected for
right-hand grip strength and left-hand grip strength, upper
36
back strength, and leg extension strength using dynamometer
measures and isometric contractions (Zuti & Corbin, 1977).
Johnson and Nelson (1976) established strength norms by
dividing an individual's body weight into the additional
weight lifted. Many investigators agree that since strength
is a physical component, it should be related to each
individual and it should be measured in relation to the
individual's body weight (Johnson & Nelson, 1979). Past
research has substantiated that body weight is significantly
correlated with strength and subsequently influences
accurate assessments of strength (Baumgartner & Jackson,
1982; Berger, 1962; Jackson & Frankiewicz, 1975; Jackson,
Watkins, and Patton, 1980; Johnson & Nelson, 1979; and Mood,
1980). In a recent study by Jackson, et al. (1980) designed
to study strength in men using the Universal Gym, the
researchers postulated that statistical control of the
anthropometric differences of height and weight would produce
a clearer interpretation of the underlying factors of
strength. Alpha and canonical factor analyses were applied
to the strength test. When the raw data of strength measures
were analyzed, a clear factor structure was not identified.
But when the variance associated with weight was eliminated
from the strength measures, three robust factors emerged
from the factor analyses. In conclusion, the preceding data
suggested that isotonic strength measurements in men can be
validly obtained by using upper and lower extremity strength
37
measurements if the effects of body weight are controlled.
The study also revealed that the bench press and leg
extension tests were valid isotonic measurements for upper
and lower extremity contractions, respectively. For the
purpose of the present study--to provide normative data on
isotonic strength in women using the Universal Gym bench
press and leg extension apparati while controlling for the
effects of body weight--a residual score procedure was
utilized.
The results of the present study demonstrated a
positive relationship between body weight and strength and
lean body weight and strength as was predicted. Even
though lean body weight had a higher correlation to strength
than body weight, the difference is not of sufficient
magnitude to cause a practitioner to become concerned with
lean weight and fat weight assessment. Thus, for the
practitioner, calculating LBW does not provide any more
information concerning the expression of strength--body
weight is sufficient. Percentile ranks were calculated on
the residual scores for both tests to provide a table that
both teacher and strength trainer can use to evaluate
strength performance and gain important feedback.
Conclusions
1) Since body weight is positively correlated with
strength, a residual score method was justifiably employed
.
38
to statistically control for the influences of body weight on
strength and valid norms were presented.
2) Both body weight and lean body weight were signi-
ficantly correlated with strength, yet the difference is not
of sufficient magnitude to warrant the calculation of lean
weight and fat weight. Thus, for the practitioner, body
weight can be used to validly predict strength performance
in a practical method.
3) The Spartacus model, Universal Gym can provide
reliable data for the purpose of evaluating strength
performance.
Recommendations
1) The sample size of the study could be increased
to improve the generalizability of the norms.
2) More strength norms could be established for women
by increasing the number of exercises tested on the
Universal Gym Spartacus model. For example, the arm curl
station could be used to test the biceps, brachialis and
brachioradialis, the lat pull station to test the
latissimus dorsi and biceps, and the leg curl station to
test the biceps femoris, semimembranosus, and semi-
tendinosus.
39
References
Baumgartner, T. A., & Jackson, A. S. Measurement in evalu-
ation in physical education (2nd ed.). Dubuque, Iowa:
Wm. C. Brown, 1982.
Baun, W. B., Baun, M. R., & Raven, P. B. A nomogram for the
estimate of percent body fat from genralized equations.
Research Quarterly, 1981, 52(3), 380-384.
Behnke, A. R., & Wilmore, J. H. Evaluation and regulation
of body build and composition. Englewood Cliffs,
New Jersey: Prentice-Hall, 1974.
Berger, R. A. Optimum repetitions for the development of
strength. Research Quarterly, 1962, 33(3), 334-338.
Berger, R. A. Applied exercise physiology. Philadelphia:
Lea & Febiger, 1982.
Blair, S. N., Falls, H. B., & Pate, R. R. A new physical
fitness test. The Physician and Sports Medicine,
Minneapolis: McGraw-Hill, 1983.
Clarke, H. H. The application of measurement to health
and physical education. New York: Prentice-Hall, 1945.
Conger, P. R., & McNab, R. B. Strength body composition,
and work capacity of participants and nonparticipants
in women's intercollegiate sports. Research Quarterly,
1967, 38(2), 184-191.
40
DeLorme, T. L., & Watkins, A. L. Progressive resistance
exercise. New York: Appleton-Century-Crofts, 1951.
Fleishman, E. A. The structure and measurement of physical
fitness. Englewood Cliffs, New Jersey: Prentice-Hall,
1964.
Glass, G. V., & Stanley, J. C. Statistical methods in edu-
cation and psychology. Englewood Cliffs, New Jersey:
Prentice-Hall, 1970.
Hosler, W. W., Morrow, J. R., & Jackson, A. S. Strength,
anthropometric, and speed characteristics of college
women volleyball players. Research Quarterly, 1978,
49(3), 385-388.
Jackson, A. W., Watkins, M., & Patton, R. W. A factor
analysis of twelve selected maximal isotonic strength
performances on the universal gym. Medicine and
Science in Sports & Exercise, 1980, 12(4), 274-277.
Jackson, A. S., & Frankiewicz, R. J. Factorial expressions
of muscular strength. Research Quarterly, 1975,
46(2), 206-217.
Jackson, A. S., & Pollock, M. L. Factor analysis and multi-
variate scaling of anthropometric variables for the
assessment of body composition. Medicine and Science
in Sports, 1976, 8(3), 196-203.
Johnson, B. L., & Nelson, J. K. Practical measurements for
evaluation in physical education (3rd ed.) .
Minneapolis: Burgess, 1979.
41
Lamb, D. R. Physiology of exercise: Responses and
adaptations. New York: Macmillian, 1978.
Mathews, D. K. Measurement in physical education (5th ed.).
Philadelphia: W. B. Saunders, 1978.
McArdle, W. D., Katch, F. I., & Katch, V. L. Exercise
pysiology: Energy, nutrition, and human performance.
Great Britain: Henry Kimpton, 1981.
Mood, D. P. Numbers in motion. Palo Alto, California:
Mayfield, 1980.
Morrow, J. R., James, R., Jackson, A. S., Hosler, W. W.,
& Kachurik, J. K. The importance of strength, speed,
and body size for team success in women's intercol-
legiate volleyball. Research Quarterly, 1979, 59(3),
429-437.
Patton, R. W., Watkins, M., & Jackson, A. W. A normative
assessment technique for isotonic strength in college
males on the universal gym. American Corrective
Therapy Journal, 1981, 35(3), 78-81.
Weinberg, R. S., Caldwell, P., Cornelius, W., Jackson, A.,
& Smith, J. Health related fitness: Theory and
practice. Topeka, Kansas: Jostens Publications, 1982.
Westcott, W. L. Strength fitness. Boston: Allyn and
Bacon, 1982.
Williams, M. H. Nutrition for fitness and sport. Dubuque,
Iowa: Wm. C. Brown, 1983.
42
Wilmore, J. H. Athletic training andphysial fitness
Physiological principles arid practices ofthecorndi-
tioning process. Boston: Allyn and Bacon, 1977.
Zuti, W. B., & Corbin, C. B. Physical fitness norms for
college freshmen. Research Quarterl, 1977, 48 (2) ,
499-503.
APPENDIX A
43
44
Appendix A
Informed Consent
1. The purpose of this study is to develop norms of isotonic
muscular strength in college age women using the
Universal Gym leg extension and bench press machines and
to statistically control for the influence of body
weight. You will be asked to execute a 1 RM (1 maximum
lift) on the bench press and on the leg extension. Your
skinfold measurements will be assessed using a Harpenden
skinfold caliper and subsequently be used as part of the
data needed to develop the norms.
2. I have (seen, heard) a clear explanation and understand
the nature and purpose of the procedure treatment. I
understand that the procedure to be performed is invest-
igational and that I may withdraw at any time with my
class grade not being affected as a result of my
withdrawal. With my understanding of this and having
received satisfactory answers to the questions I have
asked, I voluntarily consent to the procedure or
treatment in paragraph 1 above.
Signed: Date:'
Witness:
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