Content uploaded by Ilias Smilios
Author content
All content in this area was uploaded by Ilias Smilios on Oct 20, 2017
Content may be subject to copyright.
Physical Fitness and Performance
Hormonal Responses after Various
Resistance Exercise Protocols
ILIAS SMILIOS
1
, THEOPHILOS PILIANIDIS
1
, MICHALIS KARAMOUZIS
2
, and SAVVAS P. TOKMAKIDIS
1
1
Department of Physical Education & Sport Science, Democritus University of Thrace, Komotini, GREECE; and
2
Department of Medicine, Laboratory of Biological Chemistry, Aristotelian University of Thessaloniki, Thessaloniki,
GREECE
ABSTRACT
SMILIOS, I., T. PILIANIDIS, M. KARAMOUZIS, and S. P. TOKMAKIDIS. Hormonal Responses after Various Resistance Exercise
Protocols. Med. Sci. Sports Exerc., Vol. 35, No. 4, pp. 644–654, 2003. Purpose: This study examined the effects of the number of
sets on testosterone, cortisol, and growth hormone (hGH) responses after maximum strength (MS), muscular hypertrophy (MH), and
strength endurance (SE) protocols. Methods: Eleven young men performed multi-joint dynamic exercises using MS (5 reps at 88%
of one-repetition maximum (1-RM), 3-min rest) and MH (10 reps at 75% of 1-RM, 2-min rest) protocols with 2, 4, and 6 sets at each
exercise; and an SE (15 reps at 60% of 1-RM, 1-min rest) with 2 and 4 sets. Hormonal concentrations were measured before exercise,
immediately after, and at 15 and 30 min of recovery. Results: The number of sets did not affect the hormonal responses after the MS
protocol. Cortisol and hGH were higher (P⬍0.05) after the four-set compared with the two-set sessions in the MH and SE protocols.
No differences were observed between the six-set and the four-set sessions in the MH protocol. Cortisol and hGH were higher (P⬍
0.05) than the MS after the SE and MH protocols, and only when four and six sets were performed in the latter. hGH was higher than
the MH after the SE protocol, whether two or four sets were executed, whereas cortisol (P⬍0.05) was higher after the SE protocol
only when two sets were performed. Testosterone did not change with any workout. Conclusion: The number of sets functions up to
a point as a stimulus for increased hormonal concentrations in order to optimize adaptations with MH and SE protocols, and has no
effect on a MS protocol. Furthermore, the number of sets may differentiate long-term adaptations with MS, MH, and SE protocols
causing distinct hormonal responses. Key Words: STRENGTH, HYPERTROPHY, STRENGTH ENDURANCE, NUMBER OF
SETS, TOTAL WORK
Resistance exercise is a potent stimulus for acute
increases in the concentrations of circulating hor-
mones such as testosterone, growth hormone (hGH),
and cortisol (3,25,27). These responses may expand the
possibility of hormone-receptor interactions within the mus-
cle cells and along with the increased number of receptors
after training (18) may enhance muscle protein turnover
observed after resistance exercise (33). Testosterone and
hGH administration increase muscle protein synthesis and
promote muscle mass growth in humans (6,10), whereas
data from animal studies reveal that androgen receptor an-
tagonist (19) or hypophysectomy (1) suppresses hypertro-
phy induced by exercise. On the other hand, cortisol admin-
istration has a catabolic effect on myofibrillar proteins and
suppresses protein synthesis (4,20). Moreover, hormonal
responses play a significant role in tissue growth as well as
in the regulation of energy substrate metabolism (22) during
the recovery period after a training session. In addition,
training studies have also shown that acute responses of
hGH or changes in resting concentrations of testosterone
and cortisol or testosterone to cortisol ratio, correlate well
with changes in muscle size and strength (9,13,27).
Several resistance-training protocols have been devel-
oped to improve different aspects of the neuromuscular
system such as maximum strength, muscular hypertrophy,
and strength endurance (8). These protocols, which differ in
the configuration of the acute program variables such as
intensity, total work, and rest interval, cause different hor-
monal responses. Cortisol and hGH concentrations were
found to be higher after a muscular hypertrophy protocol
when compared with a maximum strength protocol, but
testosterone concentrations did not seem to differ
(15,23,24,25). Data on the hormonal responses after a
strength endurance protocol are not existent, however, de-
spite the fact that among other protocols, such a protocol is
also recommended for training the muscular fitness of the
population (2,7). Furthermore, it is not known whether the
Address for correspondence: Savvas P. Tokmakidis, Democritus Univer-
sity of Thrace, Dept. of Physical Education & Sport Science, Komotini 691
00, Greece; E-mail: stokmaki@phyed.duth.gr.
Submitted for publication April 2002.
Accepted for publication November 2002.
0195-9131/03/3504-0644/$3.00/0
MEDICINE & SCIENCE IN SPORTS & EXERCISE
®
Copyright © 2003 by the American College of Sports Medicine
DOI: 10.1249/01.MSS.0000058366.04460.5F
644
hormonal responses elicited by a strength endurance proto-
col are different from a maximum strength or a muscular
hypertrophy protocol.
An important factor in designing a daily or a long-term
resistance-training program is the volume of exercise de-
fined as the total amount of work performed during each
session. The appropriate amount of total work would be the
one that would induce the highest anabolic hormonal re-
sponses, or an optimum combination of anabolic and cata-
bolic hormonal responses, creating the most favorable en-
vironment for neuromuscular adaptations. A simple way to
modify total work is to alter the number of sets performed
at each exercise. Previous research has shown that the num-
ber of sets affects hormonal concentrations. More specifi-
cally, the performance of three sets at each exercise resulted
in higher testosterone, hGH, and cortisol responses as com-
pared with the performance of one set (11,30). However, it
is unknown whether a higher number of sets would have
caused higher hormonal concentrations as well or if there is
a point above which an increase in the number of sets does
not induce higher hormonal responses. Furthermore, the
effects of the number of sets on hormonal responses have
been studied only in a hypertrophy protocol and not in a
maximum strength or a strength endurance protocol. A
study on the above questions may provide important infor-
mation for the selection of the appropriate number of sets
when designing various resistance-training programs.
Total work may also contribute to the differences ob-
served in the hormonal responses among the various resis-
tance-exercise protocols. When an equal number of sets is
performed at each exercise, total work is higher after a
strength endurance protocol than after a hypertrophy proto-
col, whereas a maximum strength protocol yields the lowest
total work. Changes in the number of sets modify the dif-
ferences in the amount of total work among the training
protocols, and the question arises whether this could affect
the differences observed in the hormonal responses, as well.
The purpose of the present study was a) to examine the
effects of the number of sets (i.e., 2, 4, and 6 sets) performed
at each exercise on testosterone, cortisol, and hGH re-
sponses after a maximum strength, muscular hypertrophy,
and strength endurance resistance-training protocol and b)
to investigate whether the number of sets affects the varia-
tion in the hormonal responses among the three protocols
where intensity, repetitions, and rest intervals within each
protocol were kept constant.
METHODS
Subjects
Eleven men volunteered to participate in this study. Be-
fore the initiation of the study, a written informed consent
was obtained from each subject, and the experimental pro-
tocol was approved by the Institutional Review Board Com-
mittee. The physical characteristics of the subjects were the
following: age 23 ⫾4 yr, height 181 ⫾6 cm, body mass 80
⫾6 kg, and body fat 11 ⫾4%. Subjects had 2–8yrof
resistance-training experience, but no one was a competitive
lifter or trained systematically for any sport for the last 3 yr.
They were training two to three times per week with a
nonperiodized program for volume and intensity with loads
70–90% of one-repetition maximum (1-RM) and rest peri-
ods of 2–5 min between sets.
Experimental Design
All subjects performed eight workouts in order to com-
pare the hormonal responses among a maximum strength,
muscular hypertrophy, and strength endurance resistance
exercise protocol as well as the effect of the number of sets
within each protocol. The maximum strength and the mus-
cular hypertrophy protocols were performed on three sepa-
rate occasions with 2, 4, and 6 sets at each exercise, whereas
the strength endurance protocol was executed on two sep-
arate occasions with 2 and 4 sets (even 4 sets were very
stressful in the strength endurance protocol, and all subjects
refused to perform 6 sets). In addition, the subjects partic-
ipated in a control session in order to account for the effects
of circadian rhythm on the hormonal concentrations. All
exercise sessions, and the control session, were performed
in random order with 1-wk intervals.
Exercise Protocols
Selection of exercises and strength measure-
ment. The training protocols consisted of four exercises,
which activated large muscle masses, performed in the fol-
lowing order: bench press, lateral pulldowns, squat, and
overhead press. All exercises were executed using free
weights except the lat pulldowns, which were performed
using a Universal weight machine. Maximum strength at
each exercise was measured with the 1-RM method.
Maximum strength protocol (MS). In the MS pro-
tocol, the initial intensity was 88% of the 1-RM for the
bench press, lat pulldowns, and squat and 80% for the
overhead press; five repetitions were performed at each set,
and the rest interval between sets was 3 min. The intensity
was reduced after the second set in order to allow the
subjects to complete five repetitions at all sets (i.e., bench
press, lat pulldowns and squat combined: third set 83.85 ⫾
3.33, fourth set 82.38 ⫾3.64, fifth set 80.83 ⫾4.37, and
sixth set 79.51 ⫾4.48% of the 1-RM; overhead press: third
set 75.23 ⫾5.78, fourth set 73.24 ⫾7.13, fifth set 71.97 ⫾
8.14, and sixth set 70.92 ⫾7.58% of the 1-RM.
Muscular hypertrophy protocol (MH). In the MH
protocol, the initial intensity was 75% of the 1-RM for the
bench press, lat pulldowns, and squat and 68% for the
overhead press; 10 repetitions were performed at each set,
and the rest interval between sets was 2 min. The intensity
was reduced after the second set in order to allow the
subjects to complete ten repetitions at all sets (i.e., bench
press, lat pulldowns, and squat combined: third set 69.16 ⫾
4.43, fourth set 65.11 ⫾5.32, fifth set 61.03 ⫾6.28, and
sixth set 58.94 ⫾6.68% of the 1-RM; overhead press: third
set 57.4 ⫾7.67, fourth set 52.34 ⫾8.58, fifth set 45.15 ⫾
9.98, and sixth set 43.42 ⫾10.31% of the 1-RM.
HORMONAL RESPONSES TO RESISTANCE EXERCISE Medicine & Science in Sports & Exercise姞
645
Strength endurance protocol (SE). In the SE proto-
col, the initial intensity was 60% of the 1-RM for the bench
press, lat pulldowns, and squat and 52% for the overhead
press; 15 repetitions were performed at each set, and the rest
interval between sets was 1 min. The intensity was reduced
after the second set in order to allow the subjects to com-
plete 15 repetitions at all sets (i.e., bench press, lat pull-
downs, and squat combined: third set 51.66 ⫾5.52 and
fourth set 45.3 ⫾6.47% of the 1-RM; overhead press: third
set 40.09 ⫾5.3 and fourth set 30.68 ⫾7.65% of the 1-RM.
All subjects completed the first two sets with the initial
load, and thereafter the load was adjusted only when the
subjects were unable to complete without assistance the re-
quired number of repetitions. At all training protocols, the rest
interval between exercises was 6 min and the rest interval
between sets was similar within each protocol regardless of the
number of sets performed at each exercise.
Calculation of total work. All exercises were struc-
tured according to the anatomical characteristics of each
subject with grip widths and positions marked and kept
constant for each exercise throughout the study. Lifting
work was calculated as the weight load ⫻the vertical
distance moved per repetition ⫻the number of repetitions.
The weights of the body segments of the subjects ⫻the
vertical distance of the center of gravity of the body seg-
ments, which were moved, were also included in the calcu-
lations (Table 1). The location of body segments centers of
gravity and the estimation of body segment weights from the
total body weight were assessed with the use of anthropo-
metrics tables (34). The distances were obtained from mea-
surements with the subjects and the equipment in the start-
ing and ending exercise positions.
Experimental Protocol
The subjects reported in the laboratory at 9:00 a.m. or at
11:30 a.m. after an overnight fast. Subjects avoided caffeine
and alcohol consumption for 24 h and did not perform
physical exercise for 48 h before the experimental sessions.
To avoid the effects of the circadian rhythm on hormonal
concentrations, each subject performed the experimental
sessions at the same time of day. The time of day that each
exercise session began was adjusted, so that the 30-min
recovery period was approximately similar for all experi-
mental sessions when blood samples were obtained. Before
each session, the subjects rested for 15 min in the supine
position, and then a preexercise blood sample was drawn via
an indwelling venous catheter placed into an antecubital
vein. Blood samples were also drawn immediately after
exercise, as well as at 15 min and at 30 min after exercise
for the determination of lactate, testosterone, cortisol, and
hGH concentrations. All blood samples were drawn with the
subjects in the supine position. In the control session, the
same procedure was followed. The subjects did not perform
any exercise protocol but sat passively for 60 min while
blood samples were obtained at the same time points as in
the experimental exercise sessions.
Before the start of the exercise protocols, stretching ex-
ercises for the muscle groups activated with selected lifts
were performed for 10 min. Before each lift, subjects per-
formed a warm-up set with 80% of the repetitions and the
resistance used in the respective exercise protocol. The
duration of the exercise protocols varied depending on the
number of sets performed at each exercise. When two sets
were performed, the duration was 30–35 min; when four
sets were performed, 50–65 min; and when six sets were
performed, 80–90 min. To complete the required number of
repetitions, some assistance was provided during the last
repetition of the strength protocol, the last two repetitions of
the hypertrophy protocol and the last three repetitions of the
strength endurance protocol without, however, removing the
weight so that the subjects would exert maximum effort.
During the training workouts and the recovery periods,
subjects were allowed to drink water ad libitum.
Blood Analyses
Ten milliliters were drawn at each sampling time; 200
L
of this whole blood were immediately added to 400-
L
trichloroacetic acid and centrifuged at 2500 rpm for 15 min.
The supernatant was removed and frozen in ⫺80°C until
later analyzed for lactate concentrations using an enzymatic
method (procedure no. 826-UV, Sigma Chemical Co., St
Louis, MO). Blood was analyzed for hemoglobin using the
cyanmethemoglobin method (procedure No. 525-A, Sigma
Chemical Co.) and for hematocrit by the microcapillary
technique. Percent changes in plasma volume were calcu-
lated using the hematocrit and hemoglobin values according
to Dill and Costill (5). The remaining blood was centrifuged
at 2500 rpm for 15 min. Serum was removed, separated into
aliquots, and frozen at ⫺80°C until analyzed. Serum was
analyzed by luminescence immunoassay (LIA) for testos-
terone with assay sensitivity ⬍0.03 nmol·L
⫺1
and intra- and
inter-assay coefficient of variability (CV) of 2.5% and 4.8%,
respectively (Ortho-Clinical Diagnostics, Johnson & John-
son Inc., Rochester NY), and for cortisol with assay sensi-
tivity ⬍3 nmol·L
⫺1
and intra- and inter-assay CV of 3.75%
and 5.9%, respectively (Ortho-Clinical Diagnostics). Serum
was analyzed by immunoradiometric assay for hGH with
assay sensitivity 0.09
g·L
⫺1
and intra- and inter-assay CV
of 3.9% and 5.2%, respectively (Medicorp Inc., Montreal,
Canada).
Statistical Analyses
A two-way ANOVA (exercise protocol ⫻time) with
repeated measures in both factors was used to examine a)
the effects of the number of sets in the MS, MH, and SE
protocols; and b) the differences among the three protocols
in the hormonal concentrations at the various time points.
TABLE 1. Total work (J) produced at each resistance exercise protocol.
Sets
Resistance Exercise Protocol
Maximum
Strength
Muscular
Hypertrophy
Strength
Endurance
2 17,327.8 30,166.3 38,362.4
4 33,280.4 58,013.1 69,757.6
6 49,536.5 82,234
646
Official Journal of the American College of Sports Medicine http://www.acsm-msse.org
The effects of the number of sets were examined with a
separate analysis for each protocol, and three separate anal-
yses were also carried out, for the performance of 2, 4, and
6 sets at each exercise, in order to examine the differences
among the training protocols. Significant differences be-
tween means were located with the Tukey HSD procedure.
The significance level was set at P⬍0.05.
RESULTS
Blood Lactate
Effects of the number of sets. Maximum strength
protocol. There were no differences in lactate concentra-
tions among the performance of 2, 4, or 6 sets (P⬎0.05;
Fig. 1A). Blood lactate concentrations were higher (P⬍
0.05) throughout the recovery period in comparison with
control session regardless of the number of sets performed.
Muscular hypertrophy protocol. When four sets were
executed, lactate concentrations were higher (P⬍0.05)
during the recovery period compared to the execution of two
and six sets (Fig. 1B). No differences (P⬎0.05) were found
between the performance of two and six sets. After all
exercise sessions, lactate concentrations were higher (P⬍
0.05) during the recovery compared with control session.
Strength endurance protocol. No differences were ob-
served between the two- and four-set sessions in lactate
concentrations (P⬎0.05; Fig. 1C). Lactate was higher (P⬍
0.05) after both the two- and four-set exercise sessions
compared with the control session.
Effects of resistance exercise protocol. Lactate
concentrations, whether 2, 4, or 6 sets were performed, were
higher (P⬍0.05) after the MH and SE protocols than after
the MS protocol, at all postexercise time points (Fig. 2).
When two sets were performed, lactate was higher (P⬍
0.05) after the SE workout than the MH workout at all
postexercise time points. However, after the execution of
four sets, the highest lactate increase (P⬍0.05) occurred
after the SE workout only immediately after exercise (Fig.
2B).
Serum Testosterone
Effects of the number of sets. Maximum strength
protocol. No differences (P⬎0.05) were observed in tes-
tosterone concentrations whether 2, 4, or 6 sets were per-
formed (Fig. 3A). Testosterone concentrations did not differ
(P⬎0.05) between the three exercise conditions and the
control session at any time point.
Muscular hypertrophy protocol. Testosterone concentra-
tions did not differ (P⬎0.05) among the performance of 2,
4, or 6 sets (Fig. 3B). No differences were observed (P⬎
0.05) between the three exercise conditions and the control
session at any time point. When four sets were performed,
testosterone concentrations were higher immediately after
exercise compared with before exercise values.
Strength endurance protocol. No differences were found
between the performance of two and four sets in testosterone
concentrations (P⬎0.05). Although testosterone was
higher after the exercise sessions compared with the control
session, during the recovery period, no significant differ-
ences were observed. When four sets were performed, tes-
tosterone concentrations were higher (P⬍0.05) immedi-
ately after exercise compared with the values before
exercise (Fig. 3C).
Effects of resistance exercise protocol. The MS,
MH, and the SE protocols did not differ (P⬎0.05) in
FIGURE 1—Lactate concentrations (x8ⴞSE) when 2, 4, and 6 sets
were performed at each exercise in a maximum strength (A), muscular
hypertrophy (B), and strength endurance (C) resistance exercise pro-
tocol and a control session. Note: a, P<0.05 from corresponding
control session value; b, P<0.05 from corresponding two-set values;
c, P<0.05 from corresponding six-set values; d, P<0.05 from
corresponding before exercise value.
HORMONAL RESPONSES TO RESISTANCE EXERCISE Medicine & Science in Sports & Exercise姞
647
testosterone response at any time point in the immediate
recovery period whether 2, 4, or 6 sets were performed at
each exercise (Fig. 4).
Serum hGH
Effects of the number of sets. Maximum strength
protocol. When four sets were performed, hGH concentra-
tions were higher (P⬍0.05) immediately after exercise
than when two sets were performed and at 15 min of
recovery than when six sets were performed. hGH concen-
trations were higher (P⬍0.05) during the whole recovery
period after the performance of two and four sets and during
the first 15 min of the recovery after six sets compared with
the control session (Fig. 5A).
Muscular hypertrophy protocol. The concentrations of
hGH after the four- and the six-set sessions were higher (P
⬍0.05) in the first 15 min of recovery compared with the
two-set session (Fig. 5B). No differences (P⬎0.05) were
FIGURE 2—Lactate concentrations (x8ⴞSE) after a maximum
strength (MS), muscular hypertrophy (MH), and strength endurance
(SE) resistance exercise protocol when 2 sets (A), 4 sets (B), and 6 sets
(C) were performed at each exercise and a control session. Note: a, P
<0.05 from corresponding control session value; b, P<0.05 from
corresponding maximum strength protocol value; c, P<0.05 from
corresponding muscular hypertrophy protocol value; d, P<0.05 from
before exercise value.
FIGURE 3—Testosterone concentrations (x8ⴞSE) when 2, 4, and 6
sets were performed at each exercise in a maximum strength (A),
muscular hypertrophy (B), and strength endurance (C) resistance
exercise protocol and a control session. Note: a, P<0.05 from before
exercise value.
648
Official Journal of the American College of Sports Medicine http://www.acsm-msse.org
observed between the four- and six-set sessions. Compared
to the control session, hGH concentrations were higher (P⬍
0.05) immediately after exercise with the performance of
two sets, during the whole recovery period with four sets
and during the first 15 min of recovery with six sets.
Strength endurance protocol. In the SE protocol, hGH
concentrations were higher (P⬍0.05) immediately after
exercise after performing four sets than two sets, whereas at
15 min, the difference between the two sessions was not
quite significant (P⫽0.06). Both exercise sessions yielded
higher hGH concentrations compared with the control ses-
sion at all postexercise time points (Fig. 5C).
Effects of resistance exercise protocol. Two-set
sessions. hGH concentrations were higher (P⬍0.05) after
the SE compared with the maximum strength and muscular
hypertrophy protocols (Fig. 4A). The MS and the MH
workouts did not yield any significant differences in hGH
throughout the measurements (Fig. 6A).
FIGURE 4—Testosterone concentrations (x8ⴞSE) after a maximum
strength (MS), muscular hypertrophy (MH), and strength endurance
(SE) resistance exercise protocol when 2 sets (A), 4 sets (B), and 6 sets
(C) were performed at each exercise and a control session. Note: a, P
<0.05 from corresponding control session value.
FIGURE 5—hGH concentrations (x8ⴞSE) when 2, 4, and 6 sets were
performed at each exercise in a maximum strength (A), muscular
hypertrophy (B), and strength endurance (C) resistance exercise pro-
tocol and a control session. Note: a, P<0.05 from corresponding
control session value; b, P<0.05 from corresponding two-set values;
c, P<0.05 from corresponding before exercise value; d, P<0.05 from
corresponding six-set values.
HORMONAL RESPONSES TO RESISTANCE EXERCISE Medicine & Science in Sports & Exercise姞
649
Four-set sessions. hGH concentrations were higher (P⬍
0.05) after the MH and SE workouts during the 30-min
recovery period compared with the MS workout (Fig. 4B).
Furthermore, hGH concentrations in the first 15 min of
recovery were higher (P⬍0.05) after the SE protocol than
after the MH protocol (Fig. 6B).
Six-set sessions. hGH concentrations in the first 15 min of
recovery were higher (P⬍0.05) after the hypertrophy
protocol compared with the maximum strength protocol and
the control session (Fig. 6C).
Serum Cortisol
Effects of the number of sets. Maximum strength
protocol. The number of sets did not affect cortisol concen-
trations. After all exercise sessions, cortisol decreased sig-
nificantly in the recovery period compared with the concen-
FIGURE 7—Cortisol concentrations (x8ⴞSE) when 2, 4, and 6 sets
were performed at each exercise in a maximum strength (A), muscular
hypertrophy (B), and strength endurance (C) resistance exercise pro-
tocol and a control session. Note: a, P<0.05 from corresponding
control session value; b, P<0.05 from corresponding two-set values;
cP<0.05 from corresponding before exercise value.
FIGURE 6—hGH concentrations (x8ⴞSE) after a maximum strength
(MS), muscular hypertrophy (MH), and strength endurance (SE) re-
sistance exercise protocol when 2 sets (A), 4 sets (B), and 6 sets (C) were
performed at each exercise and a control session. Note: a, P<0.05
from corresponding control session value; b, P<0.05 from corre-
sponding maximum strength protocol value; c, P<0.05 from corre-
sponding muscular hypertrophy protocol value; d, P<0.05 from
before exercise value.
650
Official Journal of the American College of Sports Medicine http://www.acsm-msse.org
trations before exercise. However, no exercise session
differed from the control session (P⬎0.05; Fig. 7A).
Muscular hypertrophy protocol. Cortisol concentrations
were higher after the performance of four and six sets
compared with the performance of two sets and the control
session (P⬍0.05; Fig. 7B). No differences (P⬎0.05) were
observed between the four- and six-set sessions as well as
between the two-set and control sessions.
Strength endurance protocol. After the performance of
four sets, cortisol concentrations were higher than those
observed after the two sets and the control sessions (P⬍
0.05; Fig. 7C). Cortisol at the 15 min and at the 30 min of
recovery was higher (P⬍0.05) after the two-set session
compared with the control session.
Effects of resistance exercise protocol. Two-set
sessions. Cortisol concentrations were higher (P⬍0.05)
after the SE protocol than the MS and MH protocols (Fig.
8A). No differences (P⬎0.05) were observed between the
MS and MH workouts.
Four-set sessions. Serum cortisol concentrations were
higher (P⬍0.05) after the muscular hypertrophy and
strength endurance workouts than after the maximum
strength workout. No differences (P⬎0.05) were observed
in cortisol values between the MH and the SE protocols
(Fig. 8B).
Six-set sessions. Cortisol concentrations after the muscu-
lar hypertrophy workout were higher (P⬍0.05) than the
maximum strength workout and the control session through-
out the recovery period (Fig. 8C).
Plasma volume decreased during all resistance exercise
protocols. The greatest changes were observed pre- to pos-
texercise and were as follows (means ⫾SD): maximum
strength protocol: 8.49 ⫾6.5, 8.3 ⫾2.69, and 9.08 ⫾3.71%
when 2, 4, and 6 sets were performed, respectively; mus-
cular hypertrophy protocol: 12.33 ⫾5.17, 12.41 ⫾4.67, and
9.87 ⫾2.85%, when 2, 4, and 6 sets were performed,
respectively; strength endurance protocol: 15.7 ⫾5.18 and
14.23 ⫾3.48% when two and four sets were performed,
respectively. Corrected and uncorrected data for plasma
volume changes yielded similar results. Therefore, we have
decided to present the uncorrected data because target tis-
sues are exposed to absolute hormone concentrations.
DISCUSSION
The results of this study indicate that an increase in the
number of sets performed at each exercise induces higher
hGH and cortisol responses in a hypertrophy and a strength
endurance protocol but does not affect acute hormonal re-
sponses after a strength protocol. In a hypertrophy workout,
a limit exists in the number of sets that induce higher
hormonal responses. The specific configuration of the pro-
gram variables causes distinct hGH and cortisol responses
among the three workouts. The variation in training volume
by manipulating the number of sets affects the differences in
hGH and cortisol among the training protocols.
Number of sets and maximum strength protocol.
A high number of sets may be used to optimize strength
development after a heavy-load–low-repetition strength pro-
tocol (8). However, our results indicate that these adapta-
tions may not be due to higher hormonal concentrations.
Total work was doubled and tripled, but this had no effect
on testosterone, hGH, and cortisol increases. In a strength
protocol, an increase in total work does not seem to be a
FIGURE 8—Cortisol concentrations (x8ⴞSE) after a maximum
strength (MS), muscular hypertrophy (MH), and strength endurance
(SE) resistance exercise protocol when 2 sets (A), 4 sets (B), and 6 sets
(C) were performed at each exercise and a control session. Note: a, P
<0.05 from corresponding control session value; b, P<0.05 from
corresponding maximum strength protocol value; c, P<0.05 from
corresponding muscular hypertrophy protocol value; d, P<0.05 from
before exercise value.
HORMONAL RESPONSES TO RESISTANCE EXERCISE Medicine & Science in Sports & Exercise姞
651
stimulus for higher hormonal concentrations. Nevertheless,
increased activation of intracellular mechanisms for tissue
growth or an increase in maximal neural activation of the
muscles (14), via the application of mechanical stress for a
longer period of time, with a high number of sets in a
strength protocol cannot be excluded.
Number of sets and muscular hypertrophy pro-
tocol. In agreement with other studies (11,30), a total work
effect was observed with the hypertrophy protocol. The
performance of four sets at each exercise caused higher hGH
and cortisol responses than the performance of two sets,
whereas no effect was observed on testosterone concentra-
tions. These hormonal responses may contribute to the
higher increases in strength and lean body mass and de-
creases in percent body fat observed after the long-term use
of a multiple set as compared with a single-set program (26).
Nevertheless, the increase in hGH concentrations and the
absence of a cortisol response, when two sets were per-
formed, reveal a hormonal environment that favors anabolic
processes within the muscle. In the long term, these re-
sponses may contribute to the positive adaptations in body
composition and strength capacities with low-set protocols
during the early phase of resistance training (16,26). It was
worth noting that when four sets were applied, both hGH
and cortisol were increased. The magnitude, however, of
hGH response was much larger than that of cortisol and this
may compensate for the negative effect of cortisol on pro-
tein metabolism (29).
The present study reveals a limit where the increase in the
number of sets, in a hypertrophy protocol, induces higher
hGH and cortisol responses. When six sets were executed at
each exercise, hormonal responses were not larger from
those observed after the execution of four sets. It appears
that a very high number of sets may not create a more
favorable hormonal environment for muscular adaptations.
This finding is important for designing a resistance-training
program because it could prevent increased training stress.
It should be mentioned, however, that hormonal influences
are only one of the factors for the development of muscle
strength after resistance training. Other neural or muscular
factors may be affected positively with a high number of
sets. Another factor that may influence the interaction be-
tween the number of sets and hormonal responses is the
training status of the individual. Multiple-set protocols are
more effective for well-trained athletes (21), muscle protein
turnover is reduced after resistance exercise in trained peo-
ple (33), and hormonal responses are influenced by the
training status of the individual (9). Therefore, it would be
important to determine whether there is also a point where
an increase in the number of sets fails to cause higher
hormonal responses in well-trained athletes as it was ob-
served in our recreational lifters who did not train for any
sport.
Number of sets and strength endurance proto-
col. The strength endurance protocol, in the present study,
was stressful to increase hGH and cortisol and failed to alter
testosterone significantly although the latter was consis-
tently higher compared with the control session. The rise of
hGH and cortisol concentrations may contribute to the reg-
ulation of glucose and glycogen metabolism, which was
highly activated as it shown by the lactate data. These
hormonal responses may also contribute to muscle tissue
adaptations after long-term training. Previous studies
showed that high-repetition–low-resistance training in-
creased muscle mass (17). Furthermore, we also observed a
significant volume effect on hormonal responses in the
strength endurance protocol. The doubling of sets from two
to four caused higher hGH and cortisol concentrations.
Based on these hormonal responses, it could be hypothe-
sized that the use of a moderate number of sets (3–4) would
be more effective for neuromuscular adaptations than the
use of a low (1–2) number of sets. Yet, in the present study,
even the use of two sets induced a high activation of anaer-
obic metabolism and augmented hormonal responses indi-
cating sufficient stress for adaptations after long-term train-
ing with a strength endurance protocol.
Hormonal responses in various protocols. The
different configuration of the program variables of the re-
sistance exercise protocols imposed a specific activation
pattern in neuromuscular and metabolic processes. This in
turn caused certain hormonal changes related to the total
work of the acute exercise stress. Cortisol and hGH were
higher after the hypertrophy workout than the strength
workout when a moderate (four sets) and a high (six sets)
number of sets were performed, whereas no differences
were observed after the performance of two sets. It appears
that with a low number of sets, similar long-term adapta-
tions may be observed in the muscle tissue with the use of
both protocols. A large amount of total work must be per-
formed with a hypertrophy protocol in order to produce
distinct hormonal responses and lead to different muscular
adaptations from a strength protocol. Furthermore, cortisol
and hGH were higher after the strength endurance workout
as compared with the strength and hypertrophy workouts.
However, when four sets were performed at each exercise,
the hypertrophy and the strength endurance protocols did
not differ with each other in cortisol concentrations despite
the difference in total work (11,745 J) and the shorter rest
interval (2 vs 1 min) in the latter protocol. The higher load
used in the hypertrophy protocol may compensate for the
higher total work and the shorter rest interval used in the
strength endurance protocol. Thus, total exercise stress in
the two protocols may be the reason for similar cortisol
responses. It is likely that cortisol responses to resistance
exercise depend on metabolic requirements and total exer-
cise stress.
It is interesting to note that hGH concentrations were
higher after the strength endurance protocol than after the
hypertrophy protocol. The hGH is characterized by various
metabolic actions (e.g., glycogenesis, synthesis of contrac-
tile or sarcoplasmic and mitochondrial proteins) that are
probably dictated by the cellular needs depending on the
exercise workout. Differences in the intensity of tension, as
a function of the applied load, and the amount of tension, as
a function of total work, imposed on the muscle may cause
specific intracellular needs, which may differentiate hor-
652
Official Journal of the American College of Sports Medicine http://www.acsm-msse.org
monal actions within the cell. This may occur despite the
similar or different hormonal concentrations in the circulation.
For example, high tension applied for a short time, with low
activation of anaerobic metabolism, in a strength protocol may
activate intracellular mechanisms for muscle growth despite
the low hormonal concentrations in the circulation. In the
strength endurance protocol, the low tension applied for an
extended period of time caused a high activation of anaerobic
metabolism and so the hormonal responses may activate the
process related more to the restoration of energy substrates.
Furthermore, differences in muscle tissue activation and tissue
damage with each workout may vary the acute and overnight
hormonal responses and the functions within the muscle cells
for energy provision, tissue regeneration, and overcompensa-
tion with new muscle tissue during the recovery period
(22,28,31,32). Studies have shown that resting hormonal con-
centrations may change with resistance training using maximal
and submaximal loads (13,26). However, no comparisons have
been made among various resistance exercise protocols in the
adaptations they induce in resting hormonal concentrations.
Testosterone concentrations did not change with any
workout used in the present study compared with the control
session. Similarly, other studies did not observe an effect of
resistance exercise on testosterone concentrations (27,32),
whereas others found significant increases (11,24). Testos-
terone concentrations have been even found to be sup-
pressed (32) for 13 h after a stressful resistance exercise
protocol. The different configuration of the program vari-
ables, the amount of muscle mass activated, the inclusion of
a control session in the experimental design, and the indi-
vidual variability in testosterone response may explain part
of the differences observed in the above studies. Previous
research has shown that a large difference in total work may
differentiate testosterone responses between a strength and a
hypertrophy protocol (15). However, when total work of
both a strength and a hypertrophy workout was high
(⬎30,000 J), no differences were observed in testosterone
(24,25). Similarly, in most workouts of the present study
total work was above 30,000 J, and no differences were
observed in testosterone. Undoubtedly, differences could be
observed above 30,000 J among protocols in testosterone,
but it appears that when total work is high, other training
variables (e.g., rest interval) may influence more testoster-
one responses. It seems that the exercise stimulus of the
different protocols stimulates the hypophysis–Leyding cells
axis, which controls testosterone secretion in the same mag-
nitude. However, differences in testosterone interaction with
androgen receptors when using various workouts cannot be
excluded.
Our purpose was to compare the hormonal responses
among three different protocols, just as they were used in
practice. No attempt was taken for research purposes to
equate these protocols to total work or to have similar
resting periods between sets throughout protocols. It should
be mentioned, however, that a predetermined number of
repetitions and resting periods had to be selected for each
protocol although a range of repetitions or rest intervals
could be used for each protocol (8). Both of these factors
could cause different hormonal responses, and future re-
search could examine these modifications.
Nevertheless, the intracellular processes activated by ex-
ercise determine the adaptations in the tissues. Resistance
exercise increases muscle protein turnover (33) through the
activation of molecular and cellular mechanisms (12). To
our knowledge, it is unknown how different resistance ex-
ercise routines affect the above processes within the muscle
cell. Moreover, despite the differences observed among the
various resistance exercise protocols in the acute responses
of circulating hormones, it is the interactions of the hor-
mones with the receptors that contribute to these intracel-
lular processes. Studies on the effects of the number of sets
in various resistance exercise workouts on hormone-recep-
tor interactions, the number of receptors in the muscle, and
overnight hormonal concentrations will give further insight
in the adaptations observed with resistance exercise.
In conclusion, the number of sets does not affect the
hormonal responses observed after a maximum strength,
muscular hypertrophy, and strength endurance resistance
exercise protocol in a similar manner. There appears to be a
limit above which an increase in the number of sets does not
elicit higher hormonal concentrations. Furthermore, these
different resistance exercise protocols produce distinct hor-
monal response patterns depending on the number of sets
performed at each exercise. These results should be taken
into account when trying to optimize the effectiveness of
resistance training or to induce specific adaptations in the
neuromuscular system with the use of different resistance
training protocols.
The authors would like to thank Dr. Keijo Hakkinen for his con-
structive comments during the preparation of the manuscript.
REFERENCES
1. ADAMS, G. R., and F. HADDAD. The relationship among IGF-I,
DNA content, and protein accumulation during skeletal muscle
hypertrophy. J. Appl. Physiol. 81:2509–2516, 1996.
2. AMERICAN COLLEGE OF SPORTS MEDICINE. Position stand: progres-
sion models in resistance training for healthy adults. Med. Sci.
Sports Exerc. 34:364–380, 2002.
3. BOSCO, C., R. COLLI,R.BONOMI,S.P.VON DUVILLARD, and A.
VIROU. Monitoring strength training: neuromuscular and hormonal
profile. Med. Sci. Sports Exerc. 32:202–208, 2000.
4. CROWLEY, M., and K. S. MATT. Hormonal regulation of skeletal
muscle hypertrophy in rats: the testosterone to cortisol ratio. Eur.
J. Appl. Physiol. 73:66–72, 1996.
5. DILL, B. D., and D. L. COSTILL. Calculation of percentage changes
in volume of blood, plasma and red cells in dehydration. J. Appl.
Physiol. 37:247–248, 1974.
6. FERRANDO, A. A., K. D. TIPTON,D.DOYLE,S.M.PHILLIPS,J.
CORTIELLA, and R. R. WOLFE. Testosterone injection stimulates net
protein synthesis but not tissue amino acid transport. Am. J.
Physiol. 275(Endocrinol. Metab. 38):E864–E871, 1998.
7. FEIGENBAUM, M. S., and M. L. POLLOCK. Prescription of resistance
training for health and disease. Med. Sci. Sports Exerc. 31:38–45,
1999.
8. FLECK, S. J., and W. J. KRAEMER.Designing Resistance Training
Programs. Champaign, IL: Human Kinetics, 1997, pp. 83–115.
HORMONAL RESPONSES TO RESISTANCE EXERCISE Medicine & Science in Sports & Exercise姞
653
9. FRY, A. C., W. J. KRAEMER,M.H.STONE,L.P.KOZIRIS,J.T.
THRUSH, and S. J. FLECK. Relationships between serum testoster-
one, cortisol, and weightlifting performance. J. Strength Cond.
Res. 14:338–343, 2000.
10. FRYBURG, D. A., and E. J. BARRETT. Growth hormone acutely
stimulates skeletal muscle but not whole-body protein synthesis in
humans. Metabolism 42:1223–1227, 1993.
11. GOTSHALK, L. A., C. C. LOEBEL,B.C.NINDL, et al. Hormonal
responses of multiset versus single-set heavy-resistance exercise
protocols. Can. J. Appl. Physiol. 22:244–255, 1997.
12. HADDAD, F., and G. R. ADAMS. Selected contribution: acute cellular
and molecular responses to resistance exercise. J. Appl. Physiol.
93:394–403, 2002.
13. HAKKINEN, K., A. PAKARINEN,M.ALEN,H.KAUHANEN, and P. V.
KOMI. Neuromuscular and hormonal adaptations in athletes to
strength training in two years. J. Appl. Physiol. 65:2406–2412,
1988.
14. HAKKINEN, K. Training-specific characteristics of neuromuscular
performance. In: Strength Training for Sport, W. J. Kraemer and
K. Hakkinen (Eds.). Oxford: Blackwell Science Ltd., 2002, pp.
20–36.
15. HAKKINEN, K., and A. PAKARINEN. Acute hormonal responses to
two different fatiguing heavy resistance protocols in male athletes.
J. Appl. Physiol. 74:882–887, 1993.
16. HASS, C. J., L. GARZARELLA,D.DEHOYOS, and M. L. POLLOCK.
Single versus multiple sets in long-term recreational weightlifters.
Med. Sci. Sports Exerc. 32:235–242, 2000.
17. HISAEDA, H., K. MIYAGAWA,S.KUNO,T.FUKUNAGA, and I.
MURAOKA. Influence of two different modes of resistance training
in female students. Ergonomics 39:842–852, 1996.
18. INOUE, K., S. YAMASAKI,T.FUSHIKI, et al. Rapid increase in the
number of androgen receptors following electrical stimulation of
the rat muscle. Eur. J. Appl. Physiol. 66:134–140, 1993.
19. INOUE, K., S. YAMASAKI,T.FUSHIKI,T.KANO,Y.OKADA, and E.
SUGIMOTO. Androgen receptor antagonist suppresses exercise-in-
duced hypertrophy of skeletal muscle. Eur. J. Appl. Physiol.
69:88–91, 1994.
20. KAYALI, A. G., V. R. YOUNG, and M. N. GOODMAN. Sensitivity of
myofibrillar proteins to glucocorticoid-induced muscle proteoly-
sis. Am. J. Physiol. 252(Endocrinol. Metab. 15): E621–E626,
1987.
21. KRAEMER, W. J. A series of studies: the physiological basis for
strength training in American football: fact over philosophy. J.
Strength Cond. Res. 11:131–142, 1997.
22. KRAEMER, W. J. Endocrine responses to resistance exercise. In:
Essentials of Strength Training and Conditioning, T. R. Baechle
and R. W. Earle (Eds.). Champaign, IL: Human Kinetics, 2000,
pp. 91–114.
23. KRAEMER, W. J., J. E. DZIADOS,L.J.MARCHITELLI, et al. Effects of
different heavy-resistance exercise protocols on plasma

-endor-
phin concentrations. J. Appl. Physiol. 74:450–459, 1993.
24. KRAEMER, W. J., S. E. GORDON,S.J.FLECK, et al. Endogenous
anabolic hormonal and growth factor responses to heavy resis-
tance exercise in males and females. Int. J. Sports Med. 12:228–
235, 1991.
25. KRAEMER, W. J., L. MARCHITELLI,S.E.GORDON, et al. Hormonal
and growth factor responses to heavy resistance exercise proto-
cols. J. Appl. Physiol. 69:1442–1450, 1990.
26. MARX, J. O., N. A. RATAMESS,B.C.NINDL, et al. Low-volume
circuit versus high-volume periodized resistance training in
women. Med. Sci. Sports Exerc. 33:635–643, 2001.
27. MCCALL, G. E., W. C. BYRNES,S.J.FLECK,A.DICKINSON, and W. J.
KRAEMER. Acute and chronic hormonal responses to resistance
training designed to promote muscle hypertrophy. Can. J. Appl.
Physiol. 24:96–107, 1999.
28. MCMURRAY, R. G., T. K. EUBANK, and A. C. HACKNEY. Nocturnal
hormonal responses to resistance exercise. Eur. J. Appl. Physiol.
72:121–126, 1995.
29. MEHLS, O., B. TONSHOFF,G.KOVACS,C.MAYER,J.SCRUREK, and
J. OH. Interaction between glucocorticoids and growth hormone.
Acta Paediatr. Suppl. 388:77–82, 1993.
30. MULLIGAN, S. E., S. J. FLECK,S.E.GORDON,L.P.KOZIRIS,N.T.
TRIPLETT-MCBRIDE, and W. J. KRAEMER. Influence of resistance
exercise volume on serum growth hormone and cortisol concen-
trations in women. J. Strength Cond. Res. 10:256–262, 1996.
31. NINDL, B. C., W. C. HYMER,D.R.DEAVER, and W. J. KRAEMER.
Growth hormone pulsatility profile characteristics following acute
heavy resistance exercise. J. Appl. Physiol. 91:163–172, 2001.
32. NINDL, B. C., W. J. KRAEMER,D.R.DEAVER, et al. LH secretion
and testosterone concentrations are blunted after resistance exer-
cise in men. J. Appl. Physiol. 91:1251–1258, 2001.
33. PHILLIPS, S. M., K. D. TIPTON,A.A.FERRANDO, and R. R. WOLFE.
Resistance training reduces the acute exercise induced increase in
muscle protein turnover. Am. J. Physiol. 276(Endocrinol. Metab.
39):E118–E124, 1999.
34. WINTER,D.A.Biomechanics of Human Movement. New York:
Wiley, 1979, pp. 151–152.
654
Official Journal of the American College of Sports Medicine http://www.acsm-msse.org
