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A significant portion of a recent review on the development of research-based strength training in the National Strength and Conditioning Association focused on their opinion that free weight strength training is superior to machine training for increasing muscular strength and power. The purpose of this critique is to challenge that widely held belief, trace that belief to its probable genesis, and show that it is based primarily on a plethora of unsupported opinions and one highly flawed training study rather than science-based research.
Medicina Sportiva Practica, Vol. 18, No 2: 21-39, 2017
Copyright © 2017 Medicina Sportiva
Ralph N. Carpinelli
Human Performance Laboratory, Adelphi University, Garden City, New York, 11530 USA
A significant portion of a recent review on the development of research-based strength training in the National Strength
and Conditioning Association focused on their opinion that free weight strength training is superior to machine training for
increasing muscular strength and power. The purpose of this critique is to challenge that widely held belief, trace that belief
to its probable genesis, and show that it is based primarily on a plethora of unsupported opinions and one highly flawed
training study rather than science-based research.
Key words: Resistance training, free weights, machines, burden of proof
Shurley and colleagues [1] recently documented
the chronological history of the National Strength and
Conditioning Association (NSCA), which included
the genesis and development of the Association’s pu-
blications. Because the authors specifically stated that
for several years there was araging debate about free
weights versus machines and dedicated asignificant
focus of their manuscript to the specific topic of free
weight and machine strength training, this critical
analysis will challenge the authors’ and the NSCAs
opinion that free weights are superior to machines for
increasing strength and power. There are some legi-
timate arguments for advantages and disadvantages
of all strength training equipment such as cost, space
requirements, safety, friction, degree of learning diffi-
culty, etc., which are not the focus of this commentary.
The purpose is to challenge the widely held belief that
free weights are superior to machines for increasing
muscular strength and power.
Free weights are freely moving objects such as
barbells, dumbbells, kettlebells, body mass etc. that
are used to provide resistance for strength training.
Strength training machines use aweight stack, plate
loader, pneumatic, hydraulic, or electronic devices
to provide resistance. Science dictates that the entire
burden of proof is on those who claim superiority
of one mode of training over another and that proof
must consist of peer-reviewed well-controlled strength
training studies—not books, opinions or anecdotal
Elder Viewpoint (1979)
Shurley and colleagues [1] cited a1979 NSCA
Viewpoint article by Elder entitled Machines: aviable
method for training athletes? [2]. Elder stated unequ-
ivocally that no strength training machine could even
approach the strength gains or muscle size achieved
with free weights, and that his athletes actually lost
strength after training exclusively on machines for 12
weeks. He did not report the training protocol, any
data, and most importantly, the type of machines that
the trainees used. Shurley and colleagues mentioned
that Elder tested his trainees strength only with bar-
bells. However, they did not reveal that it was only
one exercise (bench press) that was tested and the
study involved only six subjects. Elder noted that all
his subjects showed amarked improvement in muscle
hypertrophy but did not attempt to explain why their
larger muscles did not elicit strength gains. He cited
no credible evidence to support his claim regarding
the superiority of free weights and admitted he had
only his personal observation to support his opinion.
Elder also claimed that free weight training enhances
an athlete’s ability to handle freely moving objects in
aspecific sport; however, he failed again to cite any
evidence to support that opinion.
Shurley and colleagues [1] stated that it was incre-
asingly clear to the NSCA Research Committee that
they needed to preserve their academic objectivity by
testing the claims of equipment advertisers who were
closely affiliated with the Association. If the Research
Committee would have applied asimilar challenge to
the coaches who were closely affiliated with the NSCA,
perhaps the coaches’ Viewpoints, Roundtables and stu-
dies published in the NSCA journals would have had
some validity and provided agreater benefit to their
readers. Shurley and colleagues could have attempted
to explain to their readers the concept of mechanical
specificity as it relates to the modality used for training
and testing for strength, which was inherent in Elder’s
Viewpoint [2]. Astudy by Boyer [3], which was publi-
shed in one of the NSCAs journals, would have been
agood example.
Mechanical Specificity, Boyer (1990)
Boyer [3] randomly assigned 60 previously untra-
ined females (19-37 years) to one of three progressive
resistance-training programs. All subjects performed
3x10RM, 3x6RM and 3x8RM weeks 1-3, 4-6 and
7-12, respectively, on 2 lower-body and 5 upper-bo-
dy exercises 3x/week for 12 weeks. They exercised
similar muscle groups using free weights, Nautilus,
or Soloflex machines. There was asignificant pre – to
post-training decrease in thigh, arm and iliac skinfolds
and asignificant decrease in percent body fat, with no
significant difference among the groups for any anth-
ropometric variable. The free-weight group showed
significantly greater strength gains than the Nautilus
group when tested on the equipment used for training:
1RM bench press (24.5 and 15.3%), behind-the-neck
press (22.3 and 10.9%), and leg sled (15.5 and 11.2%),
for free-weight and Nautilus groups, respectively. The
Nautilus group showed significantly greater strength
gains than the free-weight group when tested on the
Nautilus machines: bench press (47.2 and 23.3%),
lateral raise (46.8 and 19.4%), and leg press (28.2
and 17.1%), for the Nautilus and free-weight groups,
respectively. Overall, the average strength gain in the
free-weight group was 20.4% (Nautilus and free-we-
ight equipment combined), while the Nautilus® group
increased 26.6% (Nautilus and free-weight equipment
combined). The Soloflex group significantly increased
strength by an average 29.5% when tested on the So-
loflex machine, an average 15.1% when tested on the
Nautilus machines, and 11.7% with the free weight
exercises. Boyer concluded that although the strength
gains were significantly greater when each group was
tested on their specific training modality, all the groups
produced comparable gains in muscular strength and
improvements in body composition.
Pipes (1978)
In another study, Pipes [4] randomly assigned 36
young males to aUniversal or Nautilus training gro-
up, and acontrol group that did not train. The two
training groups performed 3 sets of 8 repetitions with
75% 1RM on four exercises 3x/week for 10 weeks. The
1RM was reassessed every two weeks. They used the
leg press, pull-down, seated military press and biceps
curl machines by the respective Universal and Nautilus
machine manufacturers. All the groups were tested
on the four machines from both manufacturers. The
anthropometric values (lean body mass, percent fat,
skinfolds, circumferences) significantly improved in
both training groups, with no significant difference
between those groups. When tested on the Universal
machines, the group that trained on the Universal
machines showed significantly greater strength gains
than the Nautilus group on all the exercises (leg press:
28.9 vs 7.5%, pull-down: 25.4 vs 9.5%, military press:
21.9 vs 9.4%, biceps curl: 25.5 vs 9.1%). Conversely,
when tested on the Nautilus machines, the group
that trained on the Nautilus machines demonstrated
significantly greater strength gains than the Universal
group on all the exercises (leg press: 27.0 vs 7.5%, pull-
-down: 24.5 vs 10.5%, military press: 27.3 vs 12.3%,
biceps curl: 23.2 vs 7.8%). In summary, the strength
gains were approximately 2 to 3½ times greater when
the trainees were tested on the specific machine used
for training compared with a similar machine from
adifferent manufacturer. This study was another
remarkable example of the specificity of training and
testing modalities.
It is worth noting that Pipes (4) mistakenly referred
to Universal machines as constant resistance exercises
compared with the variable resistance Nautilus ma-
chines. However, Universal machines also provide
variable resistance exercise, which is discussed in detail
later. Pipes’ study was published ayear before Elder’s
Viewpoint (2), so it could have been cited by Elder
and more importantly by Shurley and colleagues (1)
to inform readers about the mechanical specificity of
training and testing modalities.
Nautilus Viewpoint (1979)
In response to Elder’s Viewpoint [2], Nautilus
expressed aViewpoint [5] that challenged Elder’s
claim that his athletes lost strength after training
with machines. At this point in the debates there
was no specific author listed for the Viewpoints from
Nautilus Sports/Medical Industries. Nautilus noted
that many strength coaches, who have abackground
in Olympic weightlifting or powerlifting, confuse
strength training with skill training. Skill training
requires the practice of the specific movement with
the specific implement of that physical activity or test.
The six subjects in Elder’s group did not practice the
specific skill of bench pressing afree weight barbell
for 12 weeks. Elder, or any other football coach,
would probably not consider having their athletes
train with free weights throughout the off-season and
not practice football skills until opening day of the
regular season. The team must practice the specific
skills involved in playing football.
Nautilus [5] noted that when used properly, free
weights are certainly aviable tool for building strength.
They manufactured and sold both machines and free
weights. Nautilus machines incorporated acam that
provided avariable external torque. The irregularly sha-
ped cam changed the length of the external moment arm
as it rotated through arange of motion. Their rationale
was to provide agreater resistance (external torque) for
each machine in the range of motion where the musc-
les produced agreater internal torque, and apply less
resistance where the muscles produce alower internal
torque. However, as noted by Shurley and colleagues
[1], Nautilus cited no evidence to support the efficacy
of the cams and their variable external torque.
It is important to recognize that free weights and
most strength training machines are variable resistance
exercises. The amount of mass that is lifted does not
change throughout the range of motion with any of
those modes of exercise. However, the external resi-
stive torque changes throughout the range of motion
[6]. Free weights have anaturally occurring, constan-
tly changing external moment arm with single joint
exercises and multiple changing external moment
arms in multiple joint exercises. Nautilus machines use
amechanically designed and engineered eccentrically
shaped pulley known as acam that varies the external
moment arm [7], and Universal machines incorporate
changing lever and pulley systems [8]. As an external
moment arm changes, so does the external torque (the
effective resistance). Free weights and plate loading or
selectorized machines all use amass to provide resi-
stance, which remains constant through the range of
motion. And they all provide an external torque, which
is variable throughout the range of motion.
Yessis Viewpoint (1980)
Shurley and colleagues [1] reported that Yessis [9]
took exception to the Nautilus discussion of strength
in his own Viewpoint. However, the Yessis Viewpoint
was actually aresponse to adifferent Nautilus Viewpo-
int [10]. Shurley and colleagues neglected to cite this
second Viewpoint (part II) by Nautilus. It was clearly
noted at the beginning of the Yessis article that this
was the Viewpoint Yessis was challenging—not the
article that Shurley and colleagues cited. Nautilus [10]
pointed out that an athlete can train explosively with
almost any exercise tool available, including Nautilus
machines. However, they believed that explosive resi-
stance exercises may be more dangerous than slower
well-controlled movements and that the higher forces
generated with explosive movements can be shown
graphically with aforce plate.
Behm and Sale (1993)
Nearly aquarter-century ago, Behm and Sale [11]
resistance trained 8 male and 8 female young univer-
sity physical education students 3x/week for 16 weeks.
All the participants performed 5 sets of maximal effort
ankle dorsiflexion exercise. One limb was restrained
and therefore restricted to an isometric muscle action.
The contralateral limb was opposed by a Cybex II
isokinetic dynamometer and was permitted to move
through the entire range of motion at its maximal
possible velocity (5.23 rad/s, 300o/s). The duration
of muscle actions was similar (~0.5s) for both limbs.
The dominant limb was randomly assigned to either
concentric or isometric muscle actions and the con-
tralateral limb was trained using the mode of exercise
not assigned to the dominant limb. At agiven session,
trainees would perform the concentric exercises first
and then the isometric muscle actions first in the next
session. This within-subject training protocol was
the researchers’ attempt to ensure acommon neural
intent to execute rapid movements and similar motor
commands to both limbs. They assessed isometric
and concentric peak torque at 8 velocities (0, 0.26,
0.52, 1.04, 1.55, 3.02, 4.19, and 5.23 rad/s). There was
asignificant increase in peak torque at all the veloci-
ties tested in both limbs. Both limbs showed asimilar
increase in isometric rate of force development (26%)
and relaxation (47%), decreased evoked twitch time to
peak torque (6%) and half-relaxation time (11%). All
of these resistance training responses in both limbs
were produced by atraining program that prevented
actual rapid movement in one of the limbs. Behm and
Sale stated that most rapid movements are pre-pro-
grammed in the central nervous system and once the
central command is discharged to the motor neurons,
that discharge cannot be modified by proprioceptive
feedback. The study they cited by Desmedt and Go-
daux [12] in support of their statement concluded
that the ballistic command mode can also operate
under isometric conditions and the recruitment of
motor units appear to be similar under isometric and
isotonic conditions. Therefore, when the intent is to
move rapidly, the motor unit discharge is the same
whether the limb actually moves rapidly, very slowly
(e.g., with aheavy resistance or when muscle fatigue is
making the exercise more difficult), or no movement
occurs. These results suggest that the principle stimu-
lus for ahigh velocity training response is the intent to
perform arapid muscle action, rather than the actual
velocity of movement.
The recommendation by Nautilus [10] for aslower,
more controlled speed of movement is not without me-
rit. Their philosophy was that movements are purpo-
sely slow only at the beginning of aset. As the muscle
fatigues toward the end of aset and after avery slow
turnaround from an eccentric to concentric muscle
action, the trainee is actually attempting to move the
resistance as fast as possible. However because of the
increased level of fatigue, the resistance is still moving
slowly. This could minimize any potential benefit
from the stretch/shortening cycle that would make
the exercise easier. Their rationale was that making
the exercise more difficult would increase the intensity
of effort, and subsequently result in agreater stimulus
to increase strength and power. Winter and colleagues
[13] have recommended the term intensity be adopted
to categorize the trainees perceived challenge and
Winter and Fowler [14] noted that the phrase intensity
of exercise should be used during the performance of
exercise to indicate the physiological, psychological
or biomechanical demand on the trainee, rather than
the amount of resistance.
Fisher and Smith (2012)
Regarding the concept of exercise intensity, Fi-
sher and Smith [15] have noted that reporting the
percentage of 1RM only represents the amount of
the resistance lifted relative to the maximal amount
of resistance for aspecific exercise. Although an
increased load may increase the effort, it is not an
accurate measure of the level of effort or intensity
exerted by the trainee. When aspecific group of
trainees complete the same range of repetitions (e.g.,
4-7, 8-12, etc.) at the same percentage of the 1RM
(e.g., 80%), the relative load is similar among the
trainees. However, it is incorrect to assume that they
are exercising at asimilar level of effort (intensity).
The authors cited studies [16-18] that reported very
large variations in the number of possible repetitions
executed at aspecific percent of the 1RM between
individuals who are previously untrained or trained,
between males and females, and among different
exercises within an individual. Fisher and Smith
discussed the study by Shimano and colleagues [18].
The next paragraph is abrief summary of the studies
by Hoeger and colleagues [16-17].
In two cross-sectional studies by Hoeger and Col-
leagues [16-17], they evaluated 40 untrained females,
26 resistance trained females, 35 untrained males,
and 25 resistance-trained males. Experience in the
resistance trained subjects ranged from two months
to four years. The maximal number of repetitions was
recorded on seven Universal machine exercises at 40,
60, and 80% 1RM in random order for each exercise.
Hoeger and colleagues noted that with agiven percent
of the 1RM subjects will differ from one another by
one to several repetitions at the point of muscular
fatigue for aspecific exercise, as well as differ from
one exercise to another within an individual. For
example, at 80% 1RM (aload commonly used for
increasing muscular strength and hypertrophy),
untrained females performed ~12, 6 and 10 repe-
titions for the leg press, thigh curl and bench press
exercises, respectively. Trained females performed
~22, 5 and 14 repetitions for the leg press, thigh curl
and bench press exercises, respectively. There was no
significant difference between untrained and trained
females for the thigh curl but significant differences
in the leg press and bench press. For the same three
exercises, untrained males executed ~15, 6 and 10
repetitions while trained males performed ~19, 7 and
12 repetitions, respectively. There was no significant
difference between untrained and trained males for
any of those exercises. Hoeger and colleagues cau-
tioned that trainees should not assume that agiven
number of repetitions is always associated with the
same percent 1RM for all exercises. Asimilar caution
is that if agroup of subjects is assigned to train with
aspecific percentage of the 1RM (e.g., 80%) with
aspecific range of repetitions (e.g., 8-10), some tra-
inees may not be able to complete 8 repetitions (good
effort/intensity but below the prescribed range of
repetitions) and some trainees may need to perform
12 or more repetitions to achieve asimilar level of
effort/intensity. And some individual trainees may
experience significantly different levels of effort/
intensity that are dependent of the specific exercise.
Based on the prevailing evidence, Fisher and Smith
[15] concluded that the misuse of the term intensity
is responsible for several potential complications and
inadequacies in research and that the use of the term
load could resolve those complications. Within the
context of resistance training, intensity is simply the
level of effort applied to agiven load.
Nautilus [10] believed that specificity of training
means that specificity is asuperlative. That is, there are
no degrees of specificity. Amovement is either specific
or it is not. They acknowledged that although it is true
that free weights require agreater element of balance
compared with most machines, free weight balancing
skills are required only by Olympic weightlifters and
powerlifters. And those athletes must specifically
practice the skill of lifting heavy weights.
Another important point Nautilus [10] stressed
was the direct relationship between muscular strength
and anaerobic muscular endurance. As the muscle
fibers within each motor unit become stronger with
training, fewer motor units are required to perform
aspecific submaximal task. Therefore, there are agre-
ater number of motor units in reserve, which results in
an enhanced anaerobic muscular endurance. Training
for muscular strength directly enhances muscular
endurance. The submaximal test should be similar
for pre – and post-testing assessments; that is, at the
same percent of the pre-training and new post-training
1RM. It should be noted that Nautilus did not cite
any references to support their training philosophies.
Nonetheless, Shurley and colleagues [1] failed to di-
scuss or even cite this thought provoking article from
Nautilus. However, they did cite the response to that
article by Yessis [9].
As noted, Shurley and colleagues [1] mentioned
briefly that there was arebuttal to the Nautilus View-
point [10] by Yessis [9] but they did not address any
of the comments by Yessis. He claimed that Nautilus
machines were useful only for building strength but
not power. However, his statement can be easily refu-
ted. Power is the result of the work produced (force x
distance) in aspecific time. For agiven range of motion
on aNautilus machine or with abarbell when the force
(the external resistance) is moved through that range
of motion in aspecific time, the result is power. When
trainees enhance their ability to increase the amount
of resistance throughout the range of motion in the
same amount of time, the power generated is greater
as well—on aNautilus machine or with free weights.
Yessis erroneously concluded that when atrainee in-
creases strength on aNautilus machine, the movement
time increases and the result is either no increase or
aloss in power. Even if his statement was true, and
he provided no evidence for support, it would also be
similar with free weights.
Yessis [9] mistakenly claimed that atrainee co-
uld not quickly transition from the eccentric to the
concentric phase of the movement on a Nautilus
machine. This type of rapid transition (stretch/
shortening cycle) may enable greater force produc-
tion; however, the momentum created by the rapid
transition unloads the muscle for the remainder of
the repetition. Consequently, the repetition becomes
easier to complete and results in adecreased inten-
sity of effort. If this were the intended—but perhaps
misguided—training protocol, it would be equally
possible to execute with aNautilus machine or free
weights. Shurley and colleagues [1] did not mention
any of these erroneous unsupported claims by Yessis
and because they failed to site the correct reference
(10) that Yessis challenged, it would be difficult for
many readers to understand the basis for the conflict
of opinions or draw their own conclusions about the
Wolf Viewpoint (1980)
Wolf [19] responded to the Yessis critique [9] with
his own Viewpoint. One of his main points was that
because the larger motor units are capable of genera-
ting the greatest forces, they contribute to the greatest
expression of power, and those motor units can be
recruited at relatively slow speeds of movement and
ahigh intensity of effort. Harman [20] has stated: “It
is incorrect to associate strength with low speed and
power with high speed” (p. 20). Wolf noted that because
astrength trained athlete can exert greater power than
an untrained person, they can generate even more dan-
gerous rapid movements. He also strongly supported
the previously discussed muscular strength-endurance
relationship noted by Nautilus.
Yessis and Wolf Viewpoints (1981-1982)
Shurley and colleagues [1] reported that Yessis [21]
and Wolf [22] had another exchange of Viewpoints,
and that there was another article from Nautilus [7].
These are afew examples of those exchanges:
• YessisattemptedtoexplainhowNautilusmachines
were built for strength development and not power.
He claimed that if a200 pound resistance is moved
2 feet in 2 seconds, 200 watts (formerly known as
foot-pounds) of power are produced. If the time
is cut in half to 1 second, 400 watts of power are
produced with only asmall change in time.
• Wolf notedcorrectly thatwattswere not for-
merly foot-pounds, but foot-pounds per second.
He also pointed out that awatt is not equal to 1
foot-pound per second, but is .74 foot-pounds
per second. Consequently Yessis’ previous and
subsequent calculations were approximately 26%
in error throughout his article. The small change
in time that was referred to by Yessis was actually
arather large decrease of 50% in his example.
• Yessisclaimedthatatraineewhoincreasesstrength
with slow speed, high intensity training will decrease
the time it takes to execute the lift with the heavier
resistance and therefore would not enhance power.
• Wolf pointed outthatYessis probablymeant to
state that the time would increase—not decrease.
However, Wolf noted that there was no evidence to
suggest that as trainees get stronger, they get slower.
• Yessisadmittedthatwhenathletesperformexplo-
sive, ballistic power movements, they become
susceptible to injury. However, he claimed that
explosive lifting is required because of the danger
inherent in their sport. Regarding explosive mo-
vements, Winter and colleagues [13] stated: “Of
particular, concern is use of the word “explosive”.
This is not aphysics term and of course nothing
actually “explodes” in the human. We recommend
that the term “explosive” no longer be used to describe
human movement” (p. 296).
• Nautilusand Wolfwere vehementlyopposed to
exposing athletes to this type of unnecessary so-
-called explosive training (forces more dangerous
than the forces in their sport activities) to suppo-
sedly prepare them to withstand other potentially
detrimental forces.
• Yessis claimedthat atrainee couldnot perform
rapid movements or a quick transition from an
eccentric to aconcentric muscle action on Nauti-
lus machines (Yessis called it aspeed of switching
• Wolfnotedthatifarapidtransitionweredesired,
it could be executed equally as well on Nautilus
machines and free weights.
The accompanying article from Nautilus [7] was
simply abrief tutorial on the concept of variable re-
sistance exercise. As noted correctly by Shurley and
colleagues [1], none of the aforementioned articles and
Viewpoints [2, 5, 7-10, 19, 21-22] cited any evidence
(strength training studies) to support their opinions
about free weights or machines.
Manning and colleagues (1990): Testing the Validity
of the Nautilus Cam
Manning and colleagues [23] recruited 22 males
and 27 females to participate in aprogressive resistance
training program for the knee extensors. The subjects
were assessed for maximal isometric knee extension
torque at 8 angles of knee flexion on aNautilus knee
extension machine. The researchers randomly assigned
the participants to one of three groups: a group that
trained with variable resistance (VR), another with
constant resistance (CR), or acontrol group. The same
Nautilus machine used for the pre – and post-training
training assessments was used for training. The VR gro-
up exercised with the variable resistance cam supplied
with the machine. The cam was replaced with acircular
sprocket for the CR group. Therefore, the only difference
in training between groups was the pattern of resistance
offered by the machine. The training groups performed
1 set of 8-12RM full range of motion knee extensions
2 or 3 times aweek for 10 weeks. Each repetition was
executed in aslow controlled manner (2s concentric, 4s
eccentric). Both groups significantly increased isometric
knee extension torque at all the angles tested with no
significant difference in strength gains between groups
at any angle. The pre – to post-training percent change
in the resistance used for training was almost twice as
great for the VR group (45.9%) compared with the CR
group (23.7%). Manning and colleagues speculated
that because the males and females in the CR group
were significantly stronger (~29%) than the VR group
prior to training, the VR group may have had agreater
potential for strength gains. Despite their contention
that the constant resistance training should result in
significant strength gains only at the weakest point in
the range of motion, they concluded that either variable
or constant resistance is sufficient to elicit full range of
motion strength gains when the exercise is performed
slowly and includes an eccentric muscle action.
Stone and Garhammer Viewpoint (1981)
Shurley and colleagues [1] claimed that the lack
of evidence supposedly changed in 1981 when Stone
and Garhammer [24] joined the debate about free
weights and machines with their own Viewpoint on
strength and power. Stone and Garhammer claimed
that there was little doubt that free weights produced
greater gains in strength and power than Nautilus and
other machines. They cited only one training study by
Stone and colleagues [25] and one study by Wathen
[26]. Wathen compared free weights with training on
aMini-Gym Leaper, which did not provide resistance
for eccentric muscle actions and is therefore irrelevant
to the discussion of free weights versus Nautilus or
other machines such as Universal that did incorporate
an eccentric component at that time. Dating back over
aquarter century, the evidence strongly suggested
that strength training protocols with acombination of
concentric and eccentric muscle actions are superior
to those using concentric-only muscle actions for
increasing muscular strength and hypertrophy [27-
29]. The study by Stone and colleagues is discussed
in great detail below.
Stone and Colleagues (1979)
Stone and colleagues [25] recruited 34 young males
who had enrolled in auniversity beginning weight
training class and initially received 4 weeks of training
both with free weights and Nautilus machines. Subjects
were then randomly assigned to progressively train
on 8 Nautilus machine exercises or with 9 free weight
exercises 3x/week for 5 additional weeks. The Nauti-
lus group performed 1 set of each exercise and had
atarget number of repetitions (from 2 to 15) to reach
muscular exhaustion. They performed each repetition
with aslow controlled movement and 1 day each week
trained with negative accentuated repetitions (by al-
ternating limbs to lower the bilateral resistance). The
free weight group varied the number of sets from 1
to 5, and repetitions varied from 3 to 12. Unlike the
Nautilus group, they trained at their greatest possible
speed of movement. The authors did not report the
intensity of effort for the free weight group.
Stone and colleagues [25] claimed that the results
of their study showed that free weight training was
superior to Nautilus training. The free weight squat
and vertical jump showed asignificantly greater in-
crease for the free weight group. However, there was
no significant difference between groups in leg press
strength, power (the Lewis formula), or body mass.
Stone and colleagues did not report any absolute pre-
-training data or percent change in strength for any
of the 17 exercises. Consequently, it is not known if
the increase or the difference in squat strength and
vertical jump had any meaningful clinical or practical
application to any other activity. The authors did not
cite any references to show any carry-over from the
squat or vertical jump exercises to any other physical
activity—other than squatting with abarbell or vertical
Stone and colleagues [25] did not have acontrol
group and there were several potential uncontrolled
independent variables such as adifferent number of
exercises, sets, repetitions, rest between sets and exer-
cises, different speed of movement and degree of effort
in the free weight group, which Stone and colleagues
failed to report. It is not known if the free weight group
performed each set to fatigue or simply executed agi-
ven number repetitions at aspecific percent of 1RM.
Stone and colleagues [25] attempted to use the Le-
wis formula, which combines body mass and jump he-
ight to estimate power. In retrospect, it is unreasonable
to transfer the height of ajump into some meaningless
estimate of muscular power. Harman and colleagues
[30] reported that compared with force-platform de-
termination, the Lewis formula underestimated peak
power by 70.1% and average power by 12.4%. They
concluded that the validity of the Lewis formula has
never been supported in ascientific peer-reviewed
journal. Consequently it is not avalid method for
estimating average or peak power generated by asub-
ject performing ajump. They recommended that the
Lewis formula be discontinued. Lower body power
estimates are not accurate because the movement
has variations in technique, muscle actions and body
mass and aweak association between jump height and
power [31]. Stone and colleagues believed that power
was the most important component for enhancing
athletic activities. However, there is very little evidence
that attempting to maximize power is related to or is
meaningful in most physical activities [31].
Stone and colleagues [25] claimed that one reason
the Nautilus machine leg press was not as effective as
free weight squats was that each plate on the machine
weighed 25 pounds and consequently the trainees in
that group could not progress in resistance similar to
the free weight group in 5, 10 and 15 pound incre-
ments. However, even if the Nautilus 2½, 5 and 7½
pound add-on plates were not available to Stone and
colleagues, they could have simply pinned one or more
2½, 5 or 10 pound plates to the weight stack.
Stone and colleagues [25] also criticized the me-
chanics of the Nautilus machine. They noted that tra-
inees have different limb lengths that create different
moment arms. Therefore, the Nautilus machine was
not likely to vary the external torque to match each
individual. That was avalid point because Nautilus
never published any information disclosing how
they estimated the strength curve on their machi-
nes. However, during the performance of abarbell
squat the external torque (the effective resistance) is
arbitrarily variable and may not match the optimal
internal torque of each individual. Free weights pro-
duce avariable resistance but it is arandom variation
that is determined by constantly changing internal
and external leverage factors throughout the range of
motion. Consequently, the resistance is too light in
some portions of the range of motion and too heavy in
other areas—the sticking zone. The trainee is limited to
using the amount of resistance that can be handled in
the sticking zone. Accordingly, the muscles are being
properly overloaded (stimulated) in the sticking zone
but not in the stronger positions.
Stone and colleagues [25] claimed that fatigue on
the Nautilus machine was likely to occur near the
completion of the concentric phase of the rep and
consequently limit movement and work output. They
claimed that these factors may limit or impede progres-
sion and thereby reduce the training effect. However,
they cited no evidence to support their claims or why
failing at any specific point in the range of motion
would significantly influence outcomes.
The Nautilus Leg Press machine in the era (circa
1980) of the study by Stone and colleagues [25] in-
corporated acam whose radius was ~19 cm from the
axis of rotation to the chain’s point of contact at the
beginning of the concentric muscle action and ~25 cm
at the end of the stroke—asteady increase of ~33% for
external effective resistance. The Nautilus Duo-Squat,
which was also aleg press machine, had anegative
cam that unwinds as it moves through the positive
stroke. It is connected to acircular sprocket ~15 cm.
Depending on the distance from the adjustable seat to
the footpads, the radius on the negative cam is ~6 cm at
the beginning of the concentric muscle action. At the
end of the positive stroke the radius is ~1 cm, which
increases the external torque by ~5-6 fold (unpubli-
shed personal observations). Both leg press machines
provided the greatest amount of resistance in the range
of motion where the trainee is the strongest.
Contrary to the previous comment by Stone and
colleagues [25] that fatigue occurs near the completion
of the concentric muscle action, it is well known that
there is an internal biomechanical and musculature
advantage toward the end (~last third) of the range of
motion in multiple joint free weight exercises such as
the squat and bench press. The use of elastic bands or
chains may compensate for that advantage with agre-
ater or variable resistance by attaching elastic bands or
chains to the barbell. Elastic bands provide increasing
resistance throughout the range of motion, whereas
chains only add resistance as they are uncoiled from
the ground. In order to avoid additional resistance in
the sticking zone of multiple joint movements such
as the squat and bench press, one could attach acable
or rope to the chains and abarbell. The cable should
be long enough to move through the sticking zone for
squats and bench presses with just the weight of the
barbell and the cable, which is negligible. Once thro-
ugh the sticking zone (~2/3 of the accent or lift), the
chain will begin coming off the floor and completely
off the floor at the end of the lift. The extra resistance
from the chains would be applied gradually only in the
mechanically strongest portion of the range of motion.
Arecent meta-analysis by Soria-Gila and colleagues
[32] included seven studies with 235 young male and
female trainees that compared groups training with
free weights combined with elastic bands or chains
and groups that followed the same training protocol
with free weights only. There was no significant diffe-
rence in strength gains between groups of previously
untrained participants. However, there were signifi-
cantly greater upper body and lower body strength
gains (bench press and squats) in experienced trainees
(>2 years weight training). Soria-Gila and colleagues
concluded: “This meta-analysis provides research-based
data supporting the benefits of VRT [variable resistance
training] using chains or elastic bands as an effective
strategy to increase strength (1RM) in athletes of diffe-
rent sports disciplines” (p. 3268).
One example from that meta-analysis [32] is astu-
dy by Anderson and colleagues [33] who recruited 44
young males and females with at least two consecutive
years of organized weight training experience and were
Division I-Auniversity athletes. All the participants
performed 2-3 sets of 2-10 reps at 72-98% 1RM for 11
upper and lower body exercises including the free we-
ight bench press and back squat 3x/week for 7 weeks.
They were randomly assigned to agroup that used free
weights only (FWR) or agroup that used free weights
combined with elastic bands (CR) on the back squat
and bench press exercises. Both groups significantly
increased bench press strength; however, the CR group
had asignificantly greater increase compared with the
FWR group (8% and 4%, respectively). Both groups
significantly increased back squat strength with the CR
group producing significantly greater gains than the
FWR group (16% and 6%, respectively). Anderson and
colleagues concluded that using heavy elastic bands
to alter the free weight resistance (bench press and
squats) resulted in greater strength gains in an already
well-trained group of athletes.
Jones (1973)
The idea for attaching chains to abarbell is nothing
new. Forty-four years ago Jones [34] noted that for
aspecific exercise, people are stronger at some points
in their range of motion. If they use resistance that they
could handle in the strongest position, then it would
be too heavy in their weakest position. Jones recalled
that 25 years prior to his writing, he first approached
this problem by using aweight that was suitable for
the weakest position and then attached chains to that
weight. As the weight was lifted, the chains were gra-
dually uncoiled from the floor, which steadily added
the weight of the chains to the barbell. Therefore, the
concept of adding chains to abarbell has existed for
at least 69 years.
Jones’ [34] solution was to design amachine with an
eccentrically shaped cam to vary the external moment
arm and hence the effective resistance throughout the
range of motion. His hyperbole when he wrote and
spoke about his Nautilus machines may have offended
or frightened some people and perhaps his statements
were the genesis of the continuous unsupported ma-
chine criticisms. However, in sharp contrast to the
machine haters, Jones noted in the same article: “The
barbell was (and is) atool capable of producing outstan-
ding degrees of muscular strength—eventually; but it is
obviously not the ideal tool” (p. 52). In the same year
[35], he stated: “Used properly, the barbell is capable of
safely producing very worthwhile results….the problem
arises from the fact that very few people use abarbell
properly. But even when it is used properly, abarbell has
certain definite limitations” (p. 4).
In abook authored by Stone and O’Bryant [36],
they noted that studies comparing machines and free
weights support the theoretical and empirical data
concerning strength and power; and noted: “These
studies include those in which exercise selection and/or
repetition schemes were made as similar as possible in
comparing modes” (p. 155). Obviously and unfortuna-
tely, their excellent recommendations for study design
and control were not included in the study by Stone
and colleagues [25].
In their study, Stone and colleagues [25] did not
indicate if the people who performed the pre – and
post-test evaluations were blinded to the mode of tra-
ining (free weights or machines). Studies with lack of
blinding tend to exaggerate intervention effects com-
pared with adequately blinded studies [37]. There is
an inherent difficulty conducting double blind studies
with resistance training. For example, trainees would
obviously know if they were exercising with free we-
ights or machines, one set or multiple sets, shorter or
longer repetition durations, etc. However, it is feasible
to blind the assessment of outcomes. Poor internal
validity such as not controlling the accuracy of 1RM
assessments and the numerous potential confounding
variables such as speed of movement and the conse-
quential differences in momentum may confound
the practical application of the results to different
populations. Perhaps it should be mandated that the
assessors are blinded in all resistance training studies.
Shurley and colleagues [1] claimed that the study
by Stone and colleagues [25] “…demonstrated greater
improvements in strength and power in abarbell tra-
ined group than in aNautilus-trained group” (p. 523).
However in contrast to the statement by Shurley and
colleagues, Stone and colleagues actually concluded:
There was no significant difference between groups
in power” (p. 160). Consequently, the statement by
Shurley and colleagues was misleading at best.
Garhammer (1978)
Stone and colleagues [25] made several other
unsubstantiated claims in their Discussion section and
they cited an article by Garhammer [38] from Track
Technique seven times in two paragraphs. For example,
they claimed that as amuscle shortens, the ability to
produce force is reduced and with free weights the
lever systems in the body will compensate for this
limiting factor. They cited only the article by Garham-
mer in an attempt to support those statements. In fact,
Garhammer made asimilar claim and in addition he
claimed that this so-called compensation would “
permit efficient continuation of the movement” (p.
2297). Garhammer failed to cite any references in his
article to support those claims. If the compensation re-
ally did permit an efficient continuation of movement,
why do most free weight exercises have sticking zones?
Stone and colleagues [25] claimed that under heavy
workloads, fatigue is more likely to occur with ma-
chines near the completion of the concentric muscle
action rather than at the beginning of the movement.
They cited the article by Garhammer [38] again. Gar-
hammer had stated: “It is possible that an athlete will be
unable to continue some movements to complete joint
extension” (p. 2297). He cited no references to support
his opinion. These examples clearly demonstrate that
when the claims by Stone and Colleagues are traced to
the references they cited for support, it is obvious that
their claims are without any scientific merit.
Garhammer [38] made several more unsubstan-
tiated claims. For example, he claimed that there is
apreferential recruitment of fast-twitch muscle fibers
with very rapid limb movements; if an athletic event
requires rapid limb movement, one must train with
predominantly explosive movements; and free weights
are far superior to expensive machines. He failed to
cite any scientific evidence to support his claims. After
he asked what sporting event would an athlete lie on
abench or sit in achair and exert force against an ob-
ject that offers increasing inertia, he then advocated
the power clean exercise because it involves muscle
groups acting across the ankle, knee and hip joints,
large muscles of the back and shoulders, is fast and
explosive, and is performed in the standing position.
He did not cite any evidence to support acarry-over
from the power clean to any athletic event. One might
ask how many sporting events besides Olympic weigh-
tlifting involve explosively lifting off the floor heavy
discs attached to aseven foot bar and then catching it
on your chest. As with the previously discussed study
by Stone and colleagues [25], Garhammer’s article
was devoid of any scientific support for his opinions
regarding strength training.
Stone and Colleagues (1979) and Berger (1962)
The consistent long term citing of ahighly flawed
study such as Stone and colleagues [25] is analogo-
us to the consistent long term citing of the study
by Berger [39] regarding single and multiple sets,
which was also cited by Shurley and colleagues [1].
The study by Berger went unchallenged for 40 years.
Carpinelli [40] challenged the validity of the study
and shortly thereafter an exchange between Berger
[41] and Carpinelli [42] was published. Berger’s stu-
dy was also cited in previous work by two authors
(Todd and Todd) of the current article by Shurley
and colleagues, but never challenged. Todd and Todd
[43] reported Berger’s results, quoted his conclusion,
and they commented: “It is beyond the scope of this
article to address the various tasty nuggets found wi-
thin Berger’s famous study” (p. 277). Unfortunately,
Todd and Todd never challenged any part of Berger’s
study, which is not unlike their failure to challenge
anything in the study by Stone and colleagues in their
most recent NSCA publication [1]. Readers can read
the tasty nuggets in the exchange between Carpinelli
and Berger and have the opportunity to decide on the
validity and relevance of the studies by Berger and
by Stone and colleagues.
In the book by Stone and O’Bryant [36], they listed
afew studies that compared different machines such
as Nautilus and Universal and they incorrectly refer-
red to Universal machines as non-variable resistance
machines. In fact, Universal machines vary the exter-
nal torque by changing the position of the fulcrum
relative to the point of application of force as the we-
ight-bearing roller arm moves further from the pivot
point at the end of the lever. That shift of the fulcrum
increases the resistance to the trainee throughout the
range of motion [8]. The article by Smith described
the variable resistance of the Universal machines and
was published in an NSCA journal two years before
the book by Stone and O’Bryant. Nevertheless, the
only studies they cited that compared machines and
free weights were the previously mentioned studies
by Stone and colleagues [25] and Wathen [26], and
astudy by Silvester and colleagues [44] that will be
discussed shortly.
Not only did Shurley and colleagues [1] fail to
mention the article on Universal machines by Smith
[8] when discussing free weights versus variable
resistance Nautilus machines but they did not cite
another variable resistance machine article in the
NSCA’s invited series of articles. Keiser [45] described
in detail how acompressor supplied air pressure to
each of their pneumatic resistance machines providing
instantaneously variable resistance for concentric and
eccentric muscle actions. The resistance is varied by
apiston compressing apre-selected amount of air in
acylinder and by differences in leverage as the machi-
ne’s linkage changed throughout the range of motion.
Perhaps Shurley and colleagues’ omission of the two
articles on strength training modes by Smith and by
Keiser was another indication of an unfounded bias
against resistance training machines and their favora-
ble unsupported opinions of free weights.
Recently, Frost and colleagues [46] compared
training with free weights or Keiser pneumatic re-
sistance on bench press strength in 18 males with
3-15 years of resistance training experience. After
they were matched for 1RM bench press, one group
trained with free weights and the other group with
pneumatic resistance. All the trainees followed asi-
milar whole body progressive resistance routine, inc-
luding the bench press exercise 3x/week for 8 weeks.
Both groups significantly increased bench press 1RM
when assessed with free weights (10.4 and 11.6%) and
pneumatic resistance (9.4 and 17.5%), free weight and
pneumatic resistance training groups, respectively.
Frost and colleagues noted that despite performing
the bench press with one specific type of resistance
(free weights or pneumatic) throughout the training,
the pre – to post-training increase in 1RM was not
significantly different between either group on both
modes of exercise.
Although it is beyond the scope of this critique, it
should be recognized that there is also aconstantly va-
riable internal torque. Some of the many elements that
affect internal torque vary within aspecific repetition
such as achange in the angle of muscle insertion and
hence achange in the internal moment arm, length of
the muscle, velocity of shortening, etc. Other internal
(muscular) elements may vary as aresult of resistance
training such as muscle cross-sectional area and force
production. Thus, the variable external (resistive)
torque at any particular point in the range of motion
may not match the variable internal (muscular) torque
with free weights or machines. As previously noted,
the claims by machine companies that their machines
are designed to provide an optimal variable resistance
are without scientific support.
Shurley and colleagues [1] stated that Stone and
Garhammer [24] concluded: “There is little doubt that
free weights, properly used, can produce greater gains
in power and strength than Nautilus and other machi-
nes” (p. 24), and they cited the two aforementioned
training studies [25-26]. Shurley and colleagues failed
to report that Stone and colleagues [25] reported no
significant difference in power. Although the title
of the article by Shurley and colleagues includes the
words The Emergence of Research-Based Strength
and Conditioning, they failed to note any of the se-
veral discrepancies between the claims by Stone and
Garhammer, the data from Stone and colleagues,
and the actual results. Shurley and colleagues also
neglected to inform their readers of all the potential
confounding variables in the highly flawed study
by Stone and colleagues. One indication of good
historical journalism is to challenge the prevailing
narrative or belief. That challenge and any research-
-based evidence are conspicuously missing from the
narrative by Shurley and colleagues.
Garhammer (1981-1982)
Shurley and colleagues [1] stated that the artic-
le by Stone and Garhammer [24] was followed by
a2-part article: part Iby Garhammer [47] and part II
by Stone [48]. Garhammer (part I) wrote extensively
about how athletes must exhibit precise coordinated
movements in their competitive events and referred
to how the body adapts to specific demands of athletic
competition. He claimed that there are neuromuscular
similarities of free weight exercises and the neuromu-
scular demands of athletic performance. However, he
did not cite any training studies to demonstrate that
free weight training has asuperior carry over to any
specific physical activity other than perhaps power-
lifting and Olympic weightlifting. Similar is not the
same as specific.
Garhammer [47] claimed that some variable re-
sistance machines, including machines with a cam,
restrict acceleration and others permit excessive
momentum. He believed that the resulting velocity
profile is significantly different from what is common
to athletic movement. However, he failed to cite any
evidence to support those claims. He noted that if
atrainee moves too fast on amachine, the resistance
will move for ashort distance on its own. Of course
because of momentum, that is also true with most free
weight exercises.
Arandjelovic [49] stated: “The greater the mo-
mentum of the load lifted, such as aweighted bar or
dumbbell, the longer the load will sustain motion aga-
inst gravity even in the absence of any additional force
exerted against it by the trainee” (p. 136). Thus, the
momentum may be used to overcome biomechanically
weak points in alift. Acompound movement such as
abarbell squat involves coordinated action of several
separate muscle groups. The momentum generated
from the full squat position can be used to overcome
apotential biomechanical weakness at the midpoint of
the concentric portion of the lift. Asimilar technique
can be used in the bench press. This phenomenon
is practiced by strength and power athletes such as
powerlifters and Olympic weightlifters and is often
used during competition to demonstrate strength and
power in aspecific lift. While actually training to build
muscular strength, power and hypertrophy, the use
of momentum to complete arepetition is commonly
known as cheating [50]. Perhaps coaches, trainers
and trainees should try to stress the difference be-
tween training for strength/power and demonstrating
When trying to understand the difference between
building muscular strength/power and demonstrating
muscular strength/power, coaches and trainees could
focus on the distinct differences between the desired
outcomes. The goal of the former is primarily chronic;
that is, to safely, effectively and efficiently as possible
apply astimulus (resistance training) that will elicit
an optimal response—an increase in strength/power.
The goal of the latter is primarily acute; that is, to move
some specific form of resistance from point Ato point
B. For example, apowerlifter or Olympic weightlifter
moving the heaviest possible resistance from point
Ato point B, or an offensive lineman moving ade-
fensive lineman from an effective position to an inef-
fective position, etc. As with any other demonstration
of strength/power, trainees must specifically practice
the desired skill.
Garhammer [47] expressed his opinion about the
importance of acounter movement (stretch/shorte-
ning cycle) in resistance training and the ability to
utilize it with free weight training. However, he ne-
glected to mention that all Nautilus machines and free
weights provide resistance for the stretch/shortening
cycle of muscle actions.
Garhammer [47] claimed that as abarbell is moved
through the range of motion and optimal internal
leverage produces the greatest internal torque, the
barbell perfectly accommodates the increased internal
(muscular) torque by accelerating at agreater rate. In
fact, the barbell responds to the larger internal force
with agreater acceleration. The greater the applied
force to agiven mass, the greater the acceleration.
During the execution of some multi-joint free weight
exercises, such as the squat, bench press and military
press, greater torque can be generated during the last
third of the concentric muscle action as compared with
the middle third, which is usually the sticking zone.
When atrainee attempts to accelerate the barbell thro-
ughout the range of motion, the greater acceleration
in the first third of the repetition produces greater
barbell momentum, which was discussed in aprevious
paragraph. The momentum helps the athlete move the
resistance through the sticking zone and makes that
part of the repetition easier and the last third of the
repetition—where the athlete is the strongest—the
easiest. The result is areduced intensity of effort thro-
ughout most of the repetition. This technique however,
is agreat asset for athletes who are demonstrating the
specific skill of powerlifting or Olympic weightlifting
but perhaps it should be minimized while building
strength thereby increasing the intensity of effort for
each repetition.
Garhammer [47] emphasized the importance
of eccentric muscle actions and correctly referred
to the insufficiency of isokinetic machines because
they did not have an eccentric component at that
time. However, all Nautilus machines have always
provided resistance for concentric and eccentric
muscle actions. Shurley and colleagues [1] claimed
that Garhammer stated that the constant velocity of
Nautilus machines were unlike sport movements.
However, Garhammer specifically stated that con-
stant velocity was inherent in isokinetic machines.
He did not refer to Nautilus machines, which are not
nor have ever been isokinetic machines. For agroup
of authors who have previously written extensively
about strength training history [43, 51-53] in the
NSCA’s Journal of Strength & Conditioning Research,
Shurley and colleagues (Todd and Todd) should have
known how Nautilus machines function. Ironically,
the Editor-in-Chief of the aforementioned journal
recently claimed that Todd and Todd were the best
resource for the study of resistance training history
and physical culture [54].
Garhammer [47] consistently attempted to use
the testimony of other coaches and weightlifters as
evidence to support his own training philosophy; that
is, he used other opinions to support his own opinions.
He stated that some physiologists and medical doctors
attempt to support aspecific training philosophy based
on hypothetical concepts but have little or no evidence
to support their philosophy. Ironically, there was an
absence of evidence to support any of Garhammer’s
Stone (1982)
Stone [48] authored the 2nd part of the 2-part
article. He stated that his intention was to inform
readers how and why free weights produce superior
results compared with machines. He began with
abrief tutorial on neuromuscular physiology and
emphasized that the timing of the firing of specific
patterns of motor units is critical for most sport ac-
tivities and that the acquisition of skill is an integral
part of strength training. He claimed that there was
little doubt from motor learning studies that similar
training activities augment performance. Stone cited
four references in an attempt to support those sta-
tements: three books, and one study on motor skills
and physical fatigue [55] that did not involve strength
training. That study compared climbing aBachman
ladder during fatigued and non-fatigued conditions.
Stone did not cite any strength training studies to
support his opinions.
Stone [48] stated that some authors have recom-
mended purposefully slow movements but that type
of slow training would result in a smaller training
effect. His rationale was that fewer fast twitch motor
units would be recruited and the lower force level
would reduce the need to increase motor unit firing
frequency and synchronization. Stone’s explanation
contradicts what is perhaps the most supported prin-
ciple in neurobiology—the size principle [56]. The
size principle states that motor units are recruited in
an orderly manner proceeding from to smaller slow
twitch motor units to the larger fast twitch motor
units, and that recruitment is based primarily on the
intensity of effort. At the end of amaximal effort set
of repetitions, all the motor units in aspecific motor
unit pool are firing at maximal capability—regardless
of the speed of movement [57].
The only strength training studies cited by Stone (48)
that compared free weights and machines are the pre-
viously discussed unrelated study by Wathen [26] and
the previously discussed deeply flawed study by Stone
and colleagues [25]. Nevertheless, Stone’s concluding
comment, which was quoted by Shurley and colleagues
[1]: “Clearly, free weights have numerous advantages
over machines” (p. 523), is without any scientific merit.
Shurley and colleagues [1] claimed: “Mike Stone
[48] refuted the Nautilus claims nearly point by point,
citing research for each contention (p. 523). Shirley and
colleagues devoted an entire paragraph to describe
how Stone allegedly refuted the claims by Nautilus. Ho-
wever, acareful reading of Stone’s article, and checking
the references he cited, reveals that Stone failed to cite
any research (strength training studies) to support his
attempt to refute the claims by Nautilus. This does not
imply that the claims by Nautilus were valid, but simply
that Stones refutations were unfounded. Apparently,
Shurley and colleagues failed to check the validity of
Stones references.
In another article, Stone and colleagues [58] stated:
The authors’ observations and those of others strongly
suggest that LBM may well be the most important factor
contributing to strength-power gains” (p. 38). Although
the authors may have really believed that lean body
mass is the greatest contributing factor to increased
strength and power, they neglected to challenge the
Viewpoint by Elder [2]. Recall that Elder reported
that as aresult of strength training with machines,
his athletes increased muscle size but antithetically
claimed that they lost strength.
Stone and Borden (1997)
Almost twenty years later, Stone and Borden [59]
claimed that studies have consistently indicated that
free weights produce superior strength gains. They
cited only four references in an attempt to support their
assertion: the previously discussed studies by Boyer [3]
and Stone and colleagues [25], and studies by Wathen
and Shutes [60] and Jesse and colleagues [61]. Similar
to the previously discussed study by Wathen [26], Wa-
then and Shutes compared barbell squat training with
training on the isokinetic concentric-only Mini-Gym
Leaper in 24 collegiate football players for 8 weeks.
There were two groups of Leaper trainees; one group
executed alower number of repetitions and the other
group ahigher number of repetitions. The authors did
not report the number of sets, repetitions, intensity or
frequency of training. The group who performed—and
practiced—the squat exercise for 8 weeks showed asi-
gnificantly greater increase in 1RM barbell squat com-
pared with the two Leaper groups. None of the groups
produced asignificant increase in vertical jump or 40
yard dash. As noted in the previously discussed study
by Wathen, the free weight group practiced the barbell
squat for 8 weeks and amajor potential confounding
variable was the lack of an eccentric component on
the Mini-Gym Leaper.
Jesse and Colleagues (1988)
Jesse and colleagues [61] randomly assigned 47
subjects to one of four training groups. Two groups
trained on aNautilus leg press machine and two groups
performed barbell squats 3x/week for 7½ weeks. One
of the two Nautilus groups used aNautilus protocol
(one set of the exercise performed purposely slow to
exhaustion) and the other followed aso-called perio-
dized protocol of progressively decreasing volume and
increasing intensity throughout the study duration.
Repetitions, sets, intensity and speed of movement
were not reported. Similarly, one of the free weight
groups performed one set of squats to exhaustion, whi-
le the other group progressed with decreased volume
and increased intensity for the 7½ weeks. All groups
significantly increased 1RM barbell squats, with both
barbell squat groups producing significantly greater
gains than the Nautilus groups. The four groups signi-
ficantly increased 1RM leg press, with no significant
difference in strength gains among the groups.
Kompf and Aradjelovic [62] have noted that the
squat is acomplex exercise from abiomechanical and
neuromuscular aspect. Given that the ascent from
the full squat position involves concentric actions of
muscle groups with antagonist functions (e.g., the
quadriceps and the hamstrings at the knee and hip),
perfecting the squat requires practice to fine tune the
timing and recruitment of the different contributing
muscles. In the aforementioned training program by
Jesse and colleagues [61], the free weight group had
an inherent advantage in the free weight 1RM squat
assessment because that group used the same equip-
ment for training and assessment, while the Nautilus
machine group did not use free weights for 7½ weeks.
The study by Jesse and colleagues [61] was publi-
shed only as an abstract with limited data and limited
information on the methodology. Consequently,
details of the progressive training protocols are unk-
nown and the only logical conclusion drawn from
the abstract is that it was more effective to practice
the barbell squat for 7½ weeks than to not squat for
7½ weeks. The authors did not report any statistical
analysis between the single set groups and the perio-
dized groups. However, the strength gains reported for
those groups in the leg press and the barbell squat were
similar and within acouple of percentage points. Any
reference to those similar strength gains in the single
set and periodized groups was conspicuously missing
from the abstract.
Stone was aco-author of the abstract by Jesse and
colleagues [61] and one of 17 authors and the cor-
responding author with the editor of ajournal who
published aCorrespondence [63] regarding single
versus multiple sets of strength training. That group of
authors desperately attempted to discredit areview by
Carpinelli and Otto [64]. One of their criticisms was
that Carpinelli and Otto used an abstract of astudy as
areference in their review. Stone and his colleagues
[63] proclaimed: “Abstracts rarely contain all the per-
tinent data, afactor well known by most exercise and
sports scientists” (p. 409). It appears that Stone’s nega-
tive opinion about citing abstracts was not applicable
to his own article because Stone and Borden [59] cited
the abstract by Jesse and colleagues.
It is also worth noting that in the aforementioned
Correspondence [63], Stone and 16 of his colleagu-
es boasted about their over 300 years of combined
weight room experience and that Carpinelli and
Otto [64] ignored the experience of the majority of
strength athletes and coaches in their review. Perhaps
their extensive experience in the weight room of
observing common strength training practices was
more of aliability than an asset to critical thinking
because many weight room practices have absolutely
no foundation in physiology. Those statements about
experience in the weight room underscored their
preference to be influenced by common practice
and opinions rather than science based resistance
training studies.
Stone and Colleagues (2000)
Three years later in asimilar article by Stone and
colleagues [65], they referred to mechanical specificity
and claimed: “The more similar atraining exercise is to
the actual physical performance, the greater the proba-
bility of transfer” (p. 66). They cited three references in
an attempt to support their claim; two books and one
peer reviewed article on the neuromuscular aspects
of resistance training by Behm [66]. When Behm
referred to movement specificity, he cited one study
by Rasch and Morehouse [67] and stated that those
authors reported larger strength gains when trainees
were tested in afamiliar position or exercise versus
atest not specific to the training mode. Briefly, Rasch
and Morehouse reported that one of their groups
of young male trainees performed 3x5RM standing
dumbbell curls 3x/week for 6 weeks. They reported
the post-training data for three different isometric
strength tests: standing with acable tensiometer at
100° elbow flexion (familiar position), supine at 100°
elbow flexion (unfamiliar position), and supine at
80° elbow flexion (another unfamiliar position—the
Martin test). Rasch and Morehouse concluded: “It
will be observed that the increases in strength following
isotonic training [dumbbells] were considerably larger
when the subject was tested in the position in which
he practiced the exercises (erect) than when tested in
aposition (supine) or by atechnique (modified Martin)
unfamiliar to him” (p. 33).
In the study by Rasch and Morehouse [67], simply
changing the position of the torso significantly affec-
ted the test outcome. For example, the strength gain
in the erect position was ~4 times greater than the
supine test and ~3 times greater than the Martin test.
Rasch and Morehouse never mentioned any transfer
of strength gains to sports performance or any other
specific physical activity. They were referring to the
difference of testing trainees either specifically the
way they were training or in some slightly unfamiliar
position. Readers may have been misled and inferred
from Stone and colleagues’ statement [65] that strength
gains after training with abarbell squat are more
effective on the performance of afootball lineman,
tennis player, hockey player, shot putter, etc. than the
strength gains produced after training on aleg press
machine. That inference is not supported by Behm’s
article or the study by Rasch and Morehouse. In fact,
most of the strength training research showed that
strength gains are specific to the mode of testing and
cited no evidence to support asuperior carry-over
of mechanical specificity to any particular sport or
physical activity.
Stone and colleagues [65] noted that only three
studies in the scientific literature used previously
trained subjects: the highly flawed previously di-
scussed study by Stone and colleagues [25], and the
studies by Wathen [26] and Wathen and Shutes [60]
who compared free weights with training on aMini-
-Gym Leaper. As previously explained, the Mini-Gym
Leaper lacks the capability to provide resistance for
eccentric muscle actions. None of these three studies
with previously trained subjects supported the supe-
riority of free weights over machines such as Nautilus
that provide resistance for concentric and eccentric
muscle actions.
Buckner and colleagues [68] explained that the
use of the word trained or the phrases recreationally
trained, well-trained, etc. are not well defined in the
literature. Some authors define trained participants
based on aspecific period of training (e.g., 6 months,
2 years, etc.); others may use either absolute or relative
strength levels as criteria or perhaps acombination of
months/years of training and strength levels. These in-
consistences make it difficult to differentiate responses
between previously untrained and so-called trained
populations [68].
Stone and colleagues [65] stated that when compa-
ring free weight with machine strength training, equal
workloads are rarely prescribed because researchers
often use the machine manufacturer’s recommended
training protocol. They referred to the previously
discussed study by Stone and colleagues [25] as an
example of using one set to failure for the Nautilus
group and multiple sets in the free weight group. Valid
research should require minimizing potential confo-
unding variables and assign similar training protocols
for afree weight versus machine training study, with
the mode of training (free weights or machines) the
only independent variable.
The same year as the article by Stone and colleagues
[65], the NSCA published aroundtable discussion of
machines versus free weights [69]. Neither Stone nor
the other contributing participants cited any additional
strength training studies that reported the superiority
of free weights over Nautilus machines.
Stone and Colleagues (2002)
Two years later, Stone and colleagues [70] claimed
again in asection entitled Machines vs Free Weights
that free weights produce superior strength gains.
They cited four studies: Boyer [3], Jesse and colleagues
[61], Stone and colleagues [25], Wathen & Shutes [60].
None of these previously discussed studies supported
their claim.
Stone and Colleagues (2007)
In a2007 book by Stone and colleagues [71] under
asection entitled Machines versus Free Weights, they
claimed that studies have consistently shown that free
weights produce superior results. They cited only the
previously discussed studies [3, 25, 60-61]. Those four
studies are apparently all they had in an attempt to
support their opinion.
Omission Bias
Shurley and colleagues [1] quoted Stone [48]and
Stone and colleagues [25] who claimed the superiority
of free weights compared with machines. Objective
journalism should have compelled Shurley and colle-
agues to report other studies that compared free weight
and Nautilus training, especially astudy by Silvester
and colleagues [44] that was published at around the
same time as the study by Stone and colleagues [25].
Studies such as the ones discussed below are conspi-
cuously missing from the narrative by Shurley and
Silvester and Colleagues (1981)
Silvester and colleagues [44] reported the results
of two experiments comparing free weights and ma-
chines. In experiment #1, 60 previously untrained
college-age males were randomly assigned to one of
three groups who performed 1x4-16RM for Nautilus
knee extension and leg press exercises, 2x7-15RM
Universal leg press, or 3x6RM free weight squats 2-3x/
week for 11 weeks. Vertical jump height showed asi-
milar significant increase for the Universal, and free-
-weight groups. The authors noted that the increases
were relatively small (~1 cm) and they were not sure
if the changes had any meaningful practical applica-
tion. There was asignificant increase in lower-body
strength (isometric knee extension and hip extension
combined) of 8.6, 9.7, and 12.5 %, for Nautilus, Uni-
versal, and free-weight groups, respectively. However,
there was no significant difference in strength gains
among the groups.
In experiment #2, Silvester and colleagues [44]
randomly assigned 48 previously untrained college-
-age males to one of four groups. Two groups perfor-
med barbell curls for either 1x10-12RM or 3x6RM,
and two groups performed Nautilus machine curls
1x6RM or 3x6RM with approximately 80% 1RM. All
the groups trained 3x/week for 8 weeks. The four
groups significantly increased isometric elbow-fle-
xion strength (average of the four angles tested) after
training with 1 set of barbell curls (23.0%), 3 sets of
barbell curls (33.0%), 1 set of Nautilus machine curls
(26.2%) or 3 sets of machine curls (19.5%). There was
no significant difference in strength gains among
the groups at any of the four angles tested. Silvester
and colleagues concluded that “variable resistance
[Nautilus] and free weights were equally effective at
developing strength throughout the complete range of
motion” (p. 32).
Rossi and Colleagues (2016)
Rossi and colleagues [72] randomly assigned 26
young males to one of three resistance training gro-
ups. One group performed 6 sets of barbell squats for
lower body training, asecond group used aleg press
machine for 6 sets, and athird group combined 3 sets
of squats and 3 sets of leg presses. All the trainees
followed an 8-10RM progressive resistance protocol
2x/week for 10 weeks. There was asignificant increase
in fat free mass, balance test performance, vertical
jump height, and 1RM leg press, with no significant
difference among the groups for any of those outco-
mes. The squat group and the combination squat+leg
press group showed significantly greater increases in
1RM squat than the leg press group (31.5, 19.8, and
7.9%, respectively). Rossi and colleagues noted that
during the squat exercise the knees flexed to ~120°
and the hips to ~20°, while to only ~90° knee flexion
and to ~45° hip flexion on the leg press machine.
They speculated that the differences in range of mo-
tion for these two exercises could explain the greater
increase in 1RM squat for the two groups who had
practiced squatting for 10 weeks compared with the
leg press group who did not squat for 10 weeks. The
authors concluded that the three training protocols
had asimilar significant positive effect on all the
functional outcomes including the vertical jump and
balance tests.
Wirth and Colleagues (2016)
Wirth and colleagues [73] randomly assigned 78
young male and female athletes with at least six mon-
ths resistance training experience to asquat, leg press
or control group. Both training groups performed
5x8-10RM, 5x6-8RM and 5x4-6RM weeks 1-3, 4-6
and 7-8, respectively. Subjects trained 2x/week and
performed each set to momentary muscular failure.
The only difference in training protocol between the
groups was the selected exercise (barbell squat vs leg
press). The squat group significantly increased vertical
jump performance but there was no significant verti-
cal jump increase in the leg press group. The authors
concluded that the squat exercise was more effective in
enhancing jump performance. Both the squat and leg
press groups significantly increased maximal isome-
tric and dynamic strength (1RM), with no significant
difference between groups for those outcomes.
Sanders (1980)
Sanders [74] randomly assigned 22 college students
to afree-weight (bench press and behind-the-neck
seated press) or Nautilus (chest press and shoulder
press machines) training group. Both groups per-
formed 3x6RM 3x/week for 5 weeks. Strength tests
(isometric) were conducted with aload cell fastened to
atable. Elbow extensor strength significantly increased
in the free-weight (~22%) and Nautilus (~24%) gro-
ups. Shoulder flexor strength significantly increased
following free weight training (~12%) and Nautilus
training (~13%). There was no significant difference
in strength gains between the free weight and Nautilus
groups. Sanders concluded that free weights and Na-
utilus machines were equally effective for developing
muscular strength.
Langford and colleagues (2007)
Langford and colleagues [75] trained 49 healthy
young males 2x/week for 10 weeks. The subjects had
novice to intermediate resistance training experience.
All the trainees performed the bent-over row, shoulder
press, and biceps curl exercises with dumbbells. Three
groups each used adifferent type of resistance for the
bench press exercise: barbell, log bar or weight stack
machine. The relatively unstable log bar was partially
filled with water to 50 kg and they added free weight
plates to determine each trainees 3RM and the resi-
stance used for training with the log bar. All trainees
were assessed for 3RM with the barbell, log bar and
on the machine bench press as well as isokinetic peak
force on aBiodex dynamometer. They trained the
bench press using only the specific mode of exercise
assigned to their group. The bench press progressive
resistance protocol varied and ranged from 3-5 sets
and 4-12 repetitions. All three groups significantly
increased peak force and 3RM on the three modes
of exercise, with no significant difference in strength
gains among the groups when tested with the barbell
(12.9, 11.2 and 11.3%), log bar (10.5, 16.9 and 14.7%),
and machine (8.8, 11.0 and 15.8%), for the barbell,
log bar and machine training groups respectively.
Langford and colleagues stated: “Although the exercises
included for training in this study appear to differ in the
demand to control the load [log bar>barbell>machine],
the data indicate that similar strength improvement oc-
curs after short-term training with the 3 types of bench
press exercises” (p. 1065).
Langford and colleagues [75] stated: “In around-
table discussion [reference 69], investigators could not
reach aconsensus because of the lack of research data
to determine which mode of isotonic training, machine
versus free weights, better transfer strength when sub-
jects are tested on amode not used during training” (p.
1065). And perhaps most importantly: “The degree of
specificity for aresistance exercise to most effectively
enhance sport performance and prevent injury is yet to
be determined” (p. 1065).
Balachandran and colleagues (2016)
Balachandran and colleagues [76] randomly assi-
gned 29 previously untrained but independently-living
older males and females (~69 years old) to either
astanding Cybex Bravo Pro cable machine (SC) or
seated Cybex VR2 machine (SM) resistance training
protocol. The participants in the SC group executed
all cable exercises in astanding position while the SM
group performed similar exercises seated in traditional
exercise machines. All participants performed 3 sets
of 12 repetitions for 6 upper body and 4 lower body
exercises 2x/wk for 12 weeks. The assessors of all
functional outcomes were blinded to the group assign-
ments. There was asimilar session rating of perceived
exertion, volume of exercise, repetition duration, and
intensity of effort in both groups. The authors reported
similar results in both groups for most of the primary
and secondary outcomes. Balachandran and colleagues
concluded: “The primary finding of the study was that
both seated machine (SM) and standing cable (SC)
training showed clinical and statistical improvements
in physical performance, but there was no statistically
significant difference between the groups” (p. 136).
Fisher and colleagues (2012)
Fisher and colleagues [77] randomly allocated
36 young males with at least two years of resistance
training experience, which included anon-specific
variation of the deadlift exercise, to one of three
groups: MedX lumbar extension machine (LUMX),
Romanian (stiff-legged) deadlift with wrist straps
(DL), or acontrol group. The researchers assessed
maximal isometric lumbar extension torque at 12o
intervals from lumbar flexion (72o) to full lumbar
extension (0o) and tested the Romanian deadlift 1RM.
The LUMX and DL groups performed 1 set of 8-12
repetitions with ~80% of the tested functional torqu-
e/1RM at arepetition duration of 2s concentric and 4s
eccentric muscle actions to volitional fatigue 1x/week
for 10 weeks of supervised progressive training. The
Romanian 1RM deadlift significantly increased in the
DL (~16%) and LUMX (~8%) groups. The DL group
did not increase maximal lumbar extension strength
at any angle; however, the LUMX group significantly
increased lumbar extension torque at 6 of the 7 angles
in the range of motion. The authors acknowledged the
specificity of training as related to the exercise tested
but noted that although each group may have had
the disadvantage of not using the specific exercise of
the other group, the DL group showed asignificant
strength gain only when tested in the deadlift and did
not improve in lumbar extension strength; whereas
the LUMX group showed significant gains in lumbar
extension strength and deadlift 1RM as well. Given
the propensity of injury to the lumbar area its debi-
litating effects, Fisher and colleagues recommended
that if strengthening the lumbar extensors is desired,
coaches and athletes should include isolated lumbar
extension exercise at least once aweek in aresistance
training program.
Manual Resistance: Dorgo and colleagues (2009)
Dorgo and colleagues [78] recruited 84 undergra-
duate males and females for participation in a resi-
stance training program and randomly assigned them
to afree weight training group (WRT) or amanual
resistance training group (MRT). About half the sub-
jects were currently engaged in aresistance training
program. The manual resistance group used aspotter
to provide resistance to the lifter with limited equip-
ment such as PVC pipe, rope, straps, etc. and achair
or bench. Traditional weight training equipment such
barbells and dumbbells were not used. The spotter
was positioned to have amechanical advantage over
the lifter, which allowed the spotter to control the
resistance throughout the range of motion and for
aweaker spotter to apply the required resistance to
astronger lifter. The researchers developed atraining
program with exercises as similar as possible for free
weight trainees and manual resistance trainees. All the
trainees performed aprogressive resistance protocol
of 2-4 sets for 8-12RM that included 6-9 large muscle
group exercises such as the bench press, shoulder press
and squat at each session 3x/week for 14 weeks. All the
trainees performed asimilar number of exercises, rest
intervals, sets and repetitions. Both groups significan-
tly increases 1RM bench press (9.8 and 7.4%) and squat
(32.9 and 26.8%), WRT and MRT groups, respectively.
There was no significant difference in strength gains
between the WRT and MRT groups. Both groups si-
gnificantly increased bench press and squat muscular
endurance (repetitions to exhaustion with 70% of pre-
-training 1RM), with no significant difference between
groups. Dorgo and colleagues concluded: “The WRT
group had an apparent advantage in the free weight
1RM testing because the same equipment was used for
training and assessment, whereas the MRT group did not
use free weights or exercise machines during the 14 week
program. Therefore, it may be inferred that the slightly
greater strength improvements [although not statisti-
cally significant] observed for the WRT group compared
with the MRT group are attributable to training-testing
specificity rather than differences in the effectiveness of
the training modalities” (p. 302).
Muscle Hypertrophy
It should be emphasized that Shurley and colle-
agues [1] did not cite, nor is this author aware of any
resistance training studies with supporting evidence
to suggest that free weights are superior to machines
for enhancing muscle hypertrophy.
Dankel and colleagues [79] have noted that if
the percent increase in strength is recorded for each
individual within astudy, the individuals with lower
baseline values respond to agreater extent than tho-
se with higher baseline values. For example, if two
trainees each increase strength by 10 kg and one had
astarting strength of 100 kg and the other 200 kg, the
strength gains would be 10% and 5%, respectively.
The authors concluded: “The wide range of traina-
bility in response to resistance training makes taking
the percentage change an inappropriate way to analyze
the data obtained within the same study in which all
individuals undergo the same training protocol and
testing procedures” (p. 448).
With the exception of the one study by Balachan-
dran and colleagues [76], none of the aforementioned
resistance training studies discussed in this critical
analysis controlled for blinded outcomes assessments.
Consequently, all those studies were potentially sub-
jected to some degree of confirmation bias.
Many of us have experienced delusional expecta-
tions regarding one specific training protocol or mode
of exercise over another and we should be careful not
to fool ourselves and attempt to translate those beliefs
into the scientific literature without strong supporting
evidence. We find ways to fool ourselves and even an
honest person can be amaster of self-deception [80].
When writing about scientific integrity, the Nobel Pri-
ze winning theoretical physicist Dr. Richard Feynman
[81] stated: “The first principle is that you must not fool
yourself—and you are the easiest person to fool. So you
have to be very careful about that. After you’ve not fooled
yourself, it’s easy not to fool other scientists” (p. 343).
It is apparent from their extensive writing over
several decades that the NSCA, Stone, Garhammer
and many others including Shurley and colleagues
[1] sincerely believe that strength training with free
weights is superior to machines for increasing strength
and power. However, belief is not necessarily synony-
mous with validity. Those beliefs must be supported
with well-controlled resistance training studies. The
study by Stone and colleagues [25] has been consi-
stently cited for almost four decades in support of free
weights over machines. With the exception of that one
highly flawed study, all the references from that era of
the NSCA are simply unsupported opinions expressed
primarily in NSCA journals.
Shurley and colleagues [1] boasted that the NSCAs
Journal of Strength and Conditioning Research has
swelled to more than 400 articles in its most recent
volume and noted the NSCAs 40-year history and
38 years of NSCA journal publications. Considering
the plethora of opinions about free weights and ma-
chines, there should be apreponderance of strength
training studies just in the NSCAs journals that would
support their belief in the superiority of aspecific
training mode. If those studies existed, Shurley and
colleagues could have cited some of them to support
their opinion and the opinion of the NSCA that they
emphasized in their article. Practical application of
any claim for aspecific mode of exercise would re-
quire the replication of results in males and females
across different age groups in populations who train
for general fitness, health, strength and muscularity,
as well as competitive athletes.
Shurley and colleagues [1] noted that the pioneers
in the strength and conditioning profession (in the
1970s) relied on anecdotal evidence and quasi-scien-
tific assertions. Unfortunately, not much has changed
over the last 40 years.
Science dictates that the burden of proof lies en-
tirely on the claimant. An extraordinary claim such
as the NSCA’s claim for the superiority of free weight
training, which has prevailed throughout the NSCA
literature for the last 38 years, requires apreponde-
rance of extraordinary scientific evidence for support.
In the article by Shurley and colleagues [1] there is
aconspicuous absence of scientific evidence to support
the superiority of any specific mode of exercise for
increasing muscular strength, power, or hypertrophy,
rendering their opinion and the NSCAs opinion sim-
ply unsupported opinions.
The author is extremely grateful to his son Rocco,
the quintessential inspirational training partner, and
to his good friend and mentor Bob Otto, Ph.D. for his
critique of this manuscript.
The author declares no conflict of interest and
has never had afinancial or corporate affiliation with
Nautilus Sports/Medical Industries or any other ma-
chine or free weight enterprise. He has been training
safely and productively with free weights and Nautilus
machines for decades.
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Address for correspondence
Ralph N. Carpinelli
P.O. Box 241
Miller Place, NY 11764 USA
E-mail: ralphcarpinelli@optonlne.net\
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