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Journal of Exercise Physiologyonline
November 2014
Volume 17 Number 6
Editor-in-Chief
Official Research Journal of
Tommy
the American
Boone, PhD,
Society
MBA
of
Review
Board
Exercise
Physiologists
Todd Astorino, PhD
Julien Baker,
ISSN 1097-9751
PhD
Steve Brock, PhD
Lance Dalleck, PhD
Eric Goulet, PhD
Robert Gotshall, PhD
Alexander Hutchison, PhD
M. Knight-Maloney, PhD
Len Kravitz, PhD
James Laskin, PhD
Yit Aun Lim, PhD
Lonnie Lowery, PhD
Derek Marks, PhD
Cristine Mermier, PhD
Robert Robergs, PhD
Chantal Vella, PhD
Dale Wagner, PhD
Frank Wyatt, PhD
Ben Zhou, PhD
Official Research Journal
of the American Society of
Exercise Physiologists
ISSN 1097-9751
JEPonline
Acute Joint Range Effects of Exercises at Different
Strength Intensities on Unstable and Stable Platforms
Amanda Brown1, Jeferson Vianna2, Ingrid Dias3, Humberto Miranda1,
Gabriel Rodrigues Neto1, Jefferson Novaes1
1Physical
Education Graduate Program, Federal University of Rio de
Janeiro (UFRJ), Rio de Janeiro, RJ, Brazil, 2Physical Education Post
Graduation Program, University Federal of Juiz de Fora, Juiz de Fora,
Brazil, 3Medical Clinic Post Graduation Program, University Federal of
Rio de Janeiro, Rio de Janeiro, Brazil
ABSTRACT
Brown A, Vianna J, Dias I, Miranda H, Rodrigues Neto G, Novaes
J. Acute Joint Range Effects of Exercises at Different Strength
Intensities on Unstable and Stable Platforms. JEPonline 2014;17(6):
74-80. The purpose of the study was to compare the joint range
effects of bench press (BP) exercises at different strength intensities
when using an unstable platform (UP) and a stable platform (SP).
Twenty-six men performed BP tests at 60% and 80% of 1RM using an
UP and a SP. Joint amplitude was significantly higher at 80% of 1RM
than at 60% of 1RM on both platforms when measuring flexion
(P<0.001) and abduction (P=0.001). Abduction (P=0.03) and
adduction (P=0.005) were significantly higher after exercises
performed on an UP than on a SP. The comparison of the pre-test
and the post-test results showed that flexion, abduction, and
horizontal adduction were significantly higher at 80% of 1RM when
using an UP. Thus, the findings indicate that performing the BP
exercise at high intensity using an UP can improve the range of
movement in trained men.
Key Words: Resistance Exercise, Bench Press, Swiss Ball and Joint
Range
75
INTRODUCTION
While traditional strength exercises are commonly performed on stable surfaces, the use of unstable
surfaces is becoming an important strategy for the implementation of power exercises. The latter’s
popularity is associated with a greater use and application of the neuromotor and neuromuscular
systems (8). In fact, it would be difficult to find a fitness facility without an instability device such the
Swiss ball. It is an unstable base, which is considered to be an important piece of equipment that is
believed to improve physical fitness (13) and promote motor control adaptations.
Interestingly, the resistance training literature does not speak to either positive or negative effects on
joint range of motion exercises performed on unstable platforms. However, assuming that the
inherent instability of a stable training platform requires major adaptations of the neuromuscular
system (5) and that range of motion is related to the improvement of neural activities (9), it seems
likely that modifying the proprioceptive system with an instability device should produce a positive
influence on the range of motion of specific joints.
Studies (7, 11) have shown the influence of traditional strength training intensity on range of motion
(i.e., flexibility). Fatouros and colleagues (7) analyzed the effects of 24 wks of strength training at
different intensities (low intensity = 45 to 50% of 1RM, moderate intensity = 60 to 65% of 1RM, and
high intensity = 80 to 85% of 1RM) on flexibility. They concluded that flexibility demonstrated an
intensity-dependent enhancement (3 to 12% in LI, 6 to 22% in MI, and 8 to 28% in HI). Clearly, the
findings indicate that resistance training has a positive influence on range of motion.
Similarly, Novaes Neto et al. (11) compared the acute effects of training at different intensities of
resistance exercise (40%, 60%, 80%, and 100% of 1RM) on range of motion and found major
changes at the intensity of 80% 1RM. Relative to an unstable platform, it is possible that different
intensities promote greater adaptations in joint range due to increased proprioceptive system use,
which may alter the length-tension relationship of the neuromuscular system.
Given that there is limited information regarding changes in flexibility with resistance training carried
out on unstable platforms, the purpose of the present study was to compare the acute effect of a
strength exercise at different intensities of 60% and 80% of 1RM while using a stable platform (flat
bench) and an unstable platforms (Swiss ball) on joint range in recreationally trained men.
METHODS
Subjects
Twenty-six recreationally trained male volunteers (23.2 ± 3.7 yrs of age, 79.6 ± 12.3 kg, 1.77 ± 0.07
m, 25.4 ± 2.9 kg/m2) participated in the study. Based on an a priori analysis, the sample size was
determined to be sufficient to provide statistical power of 85.1%. Following the recommendations of
Beck (4), a power of 0.85, α = 0.05, correlation coefficient of 0.5, nonsphericity correction of 1 and an
effect size of 0.25 resulted in an N of 26 subjects. This a priori analysis of the statistical power was
performed to reduce the probability of type II error and to determine the minimum number of
participants required for this investigation. It was found that the sample size was sufficient to provide
statistical power of 85.1%.
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Subjects’ participation was allowed if they: (a) were not smokers; (b) did not have some type of
musculoskeletal injury; and (c) did not respond positively to any of the items of the Physical Activity
Readiness Questionnaire / PAR-Q (8).
Procedures
The study was carried out over nine visits on non-consecutive days. On the first visit, after being
informed of the risks and benefits, the subjects read and signed an informed consent form and
underwent an anthropometric assessment that was followed by a range of motion test. On the second
visit, the range of motion was retested. On the third visit through the fifth visit, the subjects performed
a familiarization bench press exercise on an unstable platform. From the sixth visit, the subjects were
randomly assigned to input offset in the following experimental conditions: (a) 60% of 1RM on the
stable platform; (b) 80% of 1RM on the stable platform; (c) 60% of 1RM on the unstable platform; and
(d) 80% of 1RM on the unstable platform.
Test of 1MR
Maximum dynamic strength was evaluated using the American College of Sports Medicine’s (1)
recommendations for performing dumbbell press exercises on a flat bench. The subjects performed
the 1RM test. Then, they were retested after 48 hrs to verify the reproducibility of the loads
encountered.
Standardized instructions regarding the procedures were previously provided. Also, various strategies
were adopted to minimize errors during the 1RM test. The subjects were verbally encouraged and
performed four trials for each exercise with a standardized rest interval of 5 min between attempts.
The maximum load achieved in the last full run was recorded as 1RM.
Range Joint
Range of motion was assessed in four joint movements of the shoulder: (a) flexion; (b) extension; (c)
abduction, and (d) horizontal adduction. All flexibility measurements were made on the right side of
the subjects, which was followed by a retest to verify the reproducibility of the results. Flexion,
extension, and abduction were performed with greater ease due to lying to neutralize the possible
compensatory movement of the subjects. Horizontal adduction of the shoulder was verified with each
subject sitting in a chair. To assess range of motion, the appraiser adjusted the subject's body to the
point of pain or anatomical limitation. The measurements were made using a Carci (0.20 x 0.05)
goniometry, using the procedures described by Norkin and White (10). The data collected at the
beginning were not available to the evaluator during the subsequent evaluation.
Statistical Analyses
The parametric assumptions of normality and sphericity were validated using the KolmogorovSmirnov test and Mauchley test, respectively. The results are presented as the mean ± standard
deviation (M ± SD). A two-way ANOVA for repeated measures was used to test the effect of the
intensity and the type of platform on joint range. When the interaction between factors was significant,
paired t tests with Bonferroni correction were used to detect specific differences. Paired t tests were
performed to compare the differences in range of motion after exercise sessions with pretest values.
The reproducibility of the measurements was assessed using an intraclass correlation coefficient
(ICC). All statistical analyses were made using SPSS software (v.19, SPSS Inc., Chicago, IL, USA),
with a significance level of 5% (P≤0.05).
77
RESULTS
An intraclass correlation coefficient was used to verify the reproducibility of the mean values in the
range of motion tests. High correlation coefficients were observed (r = 0.99) with no significant
differences between the test and retest range of motion.
Table 1 shows the effects of intensity and the type of platform on shoulder range of motion. Flexion,
extension, abduction, and adduction are shown horizontally. Shoulder flexion range of motion was
significantly greater after exercises performed at the intensity of 80% of 1RM versus the intensity of
60% of 1RM (P<0.001).
With respect to shoulder abduction, range of motion was greater after exercises at 80% of 1RM rather
than after exercises at 60% of 1RM (P=0.001), and on an UP rather than on a SP (P=0.03). However,
shoulder adduction was observed at a higher amplitude after exercise was conducted on an UP
versus on a SP (P=0.005).
When comparing the joint range of motion for the pre-test and post-test values, greater shoulder
flexion (156.0 ± 12.2 vs. 150.5 ± 15.0; P = 0.01) and shoulder abduction (157.1 ± 16.2 vs. 149.1 ±
19.6; P = 0.02) were observed after sessions held on an UP at 80% of 1RM versus the pre-test. With
respect to shoulder adduction, higher values of joint amplitude were observed after the sessions
using an UP at 60% of 1RM (44.9 ± 10.2; P = 0.02) and 80% of 1RM (45.4 ± 12.9; P = 0.02) versus
the pre-test (38.0 ± 13.7).
Table 1. Mean ± Standard Deviation of Shoulder Range of Motion after Bench Press Pre-Test
and at 60 and 80% of 1RM Performed on a Stable and Unstable Platform.
Pre-Test
60% SP
60% UP
80% SP
80% UP
Flexion
(degrees)
150.5 ± 15.0
144.4 ± 19.8
148.2 ± 16.1
153.0 ± 15.5*
156.3 ± 12.2*‡
Extension
(degrees)
17.1 ± 3.9
17.5 ± 3.8
17.8 ± 3.9
17.2 ± 3.2
17.8 ± 3.7
Abduction
(degrees)
149.1 ± 19.6
145.2 ± 17.5
149.1 ± 18.0≠
153.6 ± 14.9*
157.1 ± 16.2*≠‡
Horizontal
Adduction
(degrees)
38.0 ± 13.7
37.6 ± 11.2
44.9 ± 10.2≠†
41.8 ± 13.0
45.4 ± 12.9≠‡
SP = stable platform; UP = unstable platform. *significant difference between the intensities (60% vs. 80%). ≠significant
difference between the platforms (UP vs. SP). ‡significant difference pre-test vs. 80% UP. †significant difference pre-test
vs. 60% UP. (P<0.05)
78
DISCUSSION
The purpose of the present study was to compare the acute range of motion effects of bench press
exercises on an unstable platform (UP) and a stable platform (SP) at the intensities of 60% and 80%
of 1RM. Our main finding was that resistance exercise performed on an UP increased horizontal
abduction and adduction shoulder flexibility compared to exercise performed on a SP. These findings
are especially interested since there appears to no studies in the scientific literature that reported on
the range of motion effects of resistance exercise performed on an UP.
It is believed that the results found in the present study are a function of the changes in the
proprioceptive system caused by the instability during exercise (2). The proprioceptive system is
composed of muscles, tendons, and joints as well as proprioceptors by nociceptors, which are
essential mechanisms for the protection and organization of the complex structures involved in
human movement (3). Thus, it is speculated that a possible change in the sensitivity of proprioceptors
and the nociceptors may have modified the neurophysiological aspects of movement control, as well
as the pain threshold. The result is an increase in the subjects’ range of motion when performing
exercises on the UP. Thus, it is suggested that instability produces a positive response in flexibility.
Relative to intensity, the results of this research showed that exercise performed at 80% of 1RM
compared to 60% of 1RM increased joint motion in abduction and flexion amplitude on both platforms
amplitude. It is possible that the increased intensity caused increased tension and consequent
muscle-tendon autogenic inhibition due to the action of the Golgi tendon organs (6). In this sense, the
use of the higher intensity during resistance exercise seems to produce a reflex inhibitory response of
greater magnitude that results in lower passive tension that generates an increase in range of motion.
Results consistent with the present study were found by Fatouros et al. (7) and Novaes Neto et al.
(11) in traditional training. Fatouros et al. (7) examined the influence of different intensities of force
(40%, 60%, and 80% of 1RM) on flexibility after 6 months of training and detraining. The authors
concluded that percentages above 60% of 1RM are effective for generating flexibility gains in elderly
individuals. Although Fatouros et al. (7) observed the chronic effect of traditional strength training
intensity on flexibility in the untrained elderly and the present study verified the acute effects in young
trained subjects, it is very likely there is a direct relationship between the findings of both studies.
Recently, Novaes Neto et al. (11) compared the effect of different intensities on joint range in young
trained participants. Their subjects performed the bench press and leg press exercises at intensities
of 40%, 60%, 80%, and 100% of 1RM. The authors found significant differences in the range of
motion in flexion, abduction, and horizontal adduction for the protocol at 80% of 1RM compared with
those at pre-test. For the same training intensity compared to the pretest, the present study found
differences in the same joint movements in the bench press exercises performed on the UP, which
confirms the findings of Novaes Neto et al. (11) in traditional training. This increase from the pre-test
values indicates that, regardless of the platform, the exercise of force alone is able to improve range
of motion.
Given that much of the population has the objective of achieving maximum physical fitness results in
minimum time, the UP provides more efficient training. Also, the exercise performed at high intensity
maximizes the effects on neuromuscular and neuromotor fitness.
79
CONCLUSIONS
Our study supports the hypothesis that bench press exercises at an intensity of 80% of 1RM on an
unstable platform promotes improved range of motion in shoulder flexion, abduction, and horizontal
adduction in trained men.
Address for correspondence: Amanda Fernandes Brown, MSc, Rio de Janeiro Federal University,
Physical Education Graduation Program. Rio de Janeiro – RJ, Brazil. Zip-code 21941‐590. Phone
+55 32 9181 9213, Email: [email protected]
REFERENCES
1. ACSM. Manual do ACSM para avaliação da aptidão física relacionada à saúde. (3rd
Edition). Rio de Janeiro: Guanabara Koogan, 2011.
2. Anderson KG, Behm DG. The impact of instability resistance training on balance and stability.
Sports Med. 2005;35(1):43-53.
3. Avela J, Kyröläinen H, Komi PV. Altered reflex sensitivity after repeated and prolonged passive
muscle stretching. J Appl Physio. 1999;86(4):1283-1291.
4. Beck TW. The importance of a priori sample size estimation in strength and conditioning
research. J Strength Cond Res. 2013;27(8):2323-2337.
5. Behm DG, Anderson KG. The role of instability with resistance training. J Strength Cond Res.
2006;20(3):716-722.
6. Chalmers G. Strength training: Re‐examination of the possible role of golgi tendon organ and
muscle spindle reflexes in proprioceptive neuromuscular facilitation muscle stretching. Sports
Biomech. 2004;3(1):159-183.
7. Fatouros IG, Kambas A, Katrabasas I, Leontsini D, Chatzinikolaou A, Jamurtas AZ, et al.
Resistance training and detraining effects on flexibility performance in the elderly are intensitydependent. J Strength Cond Res. 2006;20(3):634-642.
8. Goodman CA, Pearce AJ, Nicholes CJ, Gatt BM, Fairweather IH. No difference in 1RM
strength and muscle activation during the barbell chest press on a stable and unstable surface.
J Strength Cond Res. 2008;22(1):88-94.
9. Kubo K, Kanehisa H, Kawakami Y, Fukunaga T. Elastic properties of muscle-tendon complex
in long-distance runners. Eur J Appl Physiol. 2000;81(3):181-187.
10. Norkin CC, White DJ. Measurement of Joint Motion: A Guide to Goniometry. FA Davis;
2009.
80
11. Novaes Neto LS, Bentes CM, Miranda HL, Nunes RAM, Gomes TM, Novaes JS. Efeito agudo
dos exercícios resistidos sobre o desempenho da amplitude articular. Conscientiae Saude.
2013;12(4).
12. Shephard RJ. PAR-Q, Canadian Home Fitness Test and exercise screening alternatives. Int J
Sports Med. 1988;5(3):185-195.
13. Willardson JM. Core stability training: Applications to sports conditioning programs. J Strength
Cond Res. 2007;21(3):979-985.
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