Rev Bras Fisiol exerc 2021;20(5);519-31
doi: 10.33233/rbfex.v20i5.4616
ORIGINAL ARTICLE
Resistance training of knee flexors and extensors: is there
a relationship between the number of weekly repetitions and antagonist agonist balance?
Treinamento
de resistência de flexores e extensores de joelho: existe relação entre o número
de repetições semanais e equilíbrio de agonistas antagonistas?
Rodrigo
Pereira da Silva1,3,7, Giovana Brugnerotto1, Diogo
Rodrigues1, Henrique Stelzer Nogueira 2, Dilmar Pinto
Guedes Jr1,4, Leonardo Emmanuel de Medeiros Lima5,6,
Aylton Figueira Junior5, Victor Zuniga Dourado3
1Universidade Metropolitana de Santos,
Santos, SP, Brasil
2Instituto Federal de Educação, Ciência e
Tecnologia de São Paulo
3Universidade Federal de São Paulo,
Santos, SP, Brasil
4Universidade Santa Cecilia, Santos,
Brasil
5Universidade São Judas Tadeu, São Paulo,
São Paulo, SP, Brasil
6Centro Universitário de Jaguariúna,
Jaguariúna, SP, Brasil
7Faculdade Praia Grande, Praia Grande,
SP, Brasil
Received;
March 13, 2021; Accepted: September
20, 2021.
Correspondence: Rodrigo Pereira da Silva, Avenida Gerson Maurani, 1001, Casa 77, Enseada 110440280 Guaruja SP, Brazil
Rodrigo Pereira da Silva, r.pereirads@hotmail.com
Giovana Brugnerotto: giovana.br@uol.com.br
Diogo Rodrigues: digosahy@gmail.com
Henrique Stelzer Nogueira: : stelzer.h@hotmail.com
Dilmar Pinto Guedes Jr: dilmarpintoguedesjr@gmail.com
Leonardo Emmanuel de Medeiros Lima: leonardolimadocente@gmail.com
Aylton Figueira Junior: ayltonfigueirajunior@gmail.com
Victor Zuniga Dourado: vzdourado@yahoo.com.br
Abstract
Introduction: Weekly volume training
is a monitoring method and can show balance in muscles involved in joint movements,
as quadriceps and hamstring muscles to knee extension and flexion movements. The
hamstring (H)/quadriceps (Q) ratio in isokinetic torque test is a way to analysis
for knee injury risk. Objective: To test the hypothesis that there is a relationship
between the volume of repetitions weekly resistance training and the balance of
the knee extensors and flexors muscles. Methods: To evaluate the relationship
between the weekly repetitions volume and muscle balance of knee extensors and flexors
in 21 strength trained subjects in isokinetic torque test at 60°/s and 300°/s angular
velocities. Results: The data analysis demonstrated that there was no difference
in the weekly volume of reps performed for Q and H and shows poor H/Q ratio at 60°/s,
despite of a good H/Q ratio at 300°/s. Conclusion: These data contradict
the current literature, as studies show differences in weekly volume training between
quadriceps and hamstring, as well as better values of H/Q ratio at 60°/s for no
knee injury people. Our data contribute to the ongoing discussion about muscle balance
and preservation of knee health.
Keywords: strength training; agonists and antagonists;
muscle balance; resistance training.
Resumo
Introdução: O treinamento de volume semanal é um método
de monitoramento e pode mostrar o equilíbrio dos músculos envolvidos nos movimentos
articulares, como quadríceps e isquiotibiais até os movimentos de extensão e flexão
do joelho. A relação isquiotibiais (I)/quadríceps (Q) no teste de torque isocinético
é uma forma de analisar o risco de lesão no joelho. Objetivo: Testar a hipótese
de que existe relação entre o volume de repetições semanais de treinamento de resistência
e o equilíbrio dos músculos extensores e flexores do joelho. Métodos: Avaliar
a relação entre o volume de repetições semanais e o equilíbrio muscular dos extensores
e flexores do joelho em 21 sujeitos treinados em teste de torque isocinético em
velocidades angulares de 60°/s e 300°/s. Resultados: A análise dos dados demonstrou
que não houve diferença no volume semanal de repetições realizadas para Q e I, e
apresentar ser pobre em I/Q, apesar de uma boa relação I/Q pobre em 300°/s. Conclusão:
Esses dados contradizem a literatura atual, pois estudos mostram diferenças no treinamento
de volume semanal entre quadríceps e isquiotibiais, bem como melhores valores da
relação I/Q a 60°/s para pessoas sem lesão no joelho. Nossos dados contribuem para
a discussão contínua sobre o equilíbrio muscular e a preservação da saúde do joelho.
Palavras-chave: treinamento de força; agonistas e antagonistas;
equilíbrio muscular; treinamento de resistência.
The number of repetitions
per muscle group is an important variable to determine the training volume and it
is considered important that both agonist and antagonist muscles should be equally
trained to maintain an adequate muscle balance [1]. An imbalance between agonist
and antagonist muscles could increase the risk of injury [2,3,4]. The isokinetic dynamometer
is the gold standard method to determine important muscle performance variables
such as strength, power, work, and balance in muscle groups [5].
The hamstring-to-quadriceps
ratio (H/Q) is the result of the peak torque value of knee flexors/extensors equation
in concentric/concentric mode [6,7,8]. Although some studies investigated the optimal
weekly repetitions volume per muscle group [9] and several studies have assessed
the relationship between agonist and antagonist muscles balance using the isokinetic
dynamometer [6,10,11,12,13,14], few studies have associated the weekly repetitions volume
with the deficit of knee joint flexor and extensor muscle strength. The objective
of this study is to test the hypothesis that there is a relationship between the
volume of weekly repetitions of RT and the balance of the knee extensor and flexor
muscles.
Subjects
21 subjects (male n = 10; female n = 11) were
recruited by convenience. They were training in a fitness center, with time of experience
at last three years, informed by an interview, and had no knee injuries. All subjects
were informed of the experimental procedures and subsequently provided written informed
consent to participate. The study was approved by the Research Ethics Committee
of the Metropolitan University of Santos (protocol 1.598.072).
Weekly repetitions volume
Exercises were selected considering specific
exercises for the quadriceps muscles (Q) and hamstrings muscles (H) according to
the table proposed by Teixeira et al. [15]. The analysis of weekly repetitions
volume performed per muscle group of each subject was calculated by the equation:
number of repetitions x number of sets x weekly training frequency per muscle group.
Research tool
To evaluate muscle performance and balance,
the researchers used an isokinetic dynamometer (Biodex,
Lumex Inc., Ronkonkoma, NY, USA), from the Department
of Human Movement Sciences, Epidemiology and Human Movement Laboratory (EPIMOV),
Santos (SP Brazil).
Procedures
Initially, all subjects
were familiarized with the isokinetic dynamometer test. Each subject was positioned
on the knee-testing table of the isokinetic dynamometer with the stabilization straps
across the chest and a horizontal pad over the middle third and proximal half of
the distal third of the thighs. The trunk was against the backrest of the testing
table. The knee joint axis was aligned with the mechanical axis of the dynamometer.
The initial range of motion of the knee joint was 90° flexion. Once positioned,
the subjects performed a familiarization session with three submaximal repetitions
at the same speeds used in the tests in order to reduce
the learning effects and to guarantee reproducibility of the data collecting [16].
The maximal tests and concentric contraction of extensors and flexors were performed
in the dominant limb, one with an angular velocity of 60°/s (a set of five repetitions)
and 300o/s (a set of 30 repetitions) to analyze the variables. The muscle contraction
variables measured were average peak torque, average power, total work output and
the H/Q.
The subjects performed
five cycles of the extensor/flexor muscles concentric contraction with maximal effort
and were strongly encouraged by the researcher during all the test procedure [17].
Gravitational influence was corrected during the test.
To descriptive data,
after confirmation of non-normality by Shapiro-Wilk test, Mann-Whitney test was
chosen to comparisons the body mass index (BMI), time of practice and weekly hamstring
muscle training volume, all between sexes, while after confirmation of normality,
t Student test was chosen to comparison age, weight, height ,and
weekly quadriceps muscle training volume, all between sexes. The results of sexes
comparison descriptive data do not show significant differences between sexes for
hamstring and quadriceps weekly volume training, and shows significant differences
for BMI, weight, and height. Therefore, the comparison of peak torque and muscles
volume training (hamstring and quadriceps) were limited only intragroups.
The Shapiro-Wilk
test shows non-normality for both sexes weekly hamstring and quadriceps volume training,
for all peak torque velocities, and for agonist/antagonist ratio. Therefore, Wilcoxon
test was chosen to compare intragroups the weekly training
volume of the hamstring muscle and quadriceps muscle exercises, and to comparison
between the peak torque of the knee flexors and extensors isokinetic tests. Spearman
correlation test was chosen to verify the association between weekly volume training
and muscular torque results.
The Shapiro-Wilk
test shows for H/Q at 60o/s and at 300o/s in both sexes
groups, so t Student test was chosen to compare this ratio between maximus force
(60o/s) and resistance force (300o/s). The significance adopted for all analysis
was p ≤ 0.05.
Table I shows the
general characteristics of the sample. Men are heavier and have greater height when
compared to women; therefore, in the analysis of BMI, males are classified as overweight
and females eutrophic. About the time of strength training
practice, 81% of the sample has at least 6 years of systematic and uninterrupted
training.
Table I - Data description
of participants recruited
SD = standard deviation;
kg = kilograms; m = meters; *p ≤ 0.05 by t Student test sexes comparison;
** p ≤ 0.05 by Mann-Whitney test sexes comparison
Table II shows similar
weekly training for hamstring and quadriceps in both sexes
groups. All knee extension variables produced significantly more maximum strength,
muscle endurance and muscle power when compared to knee flexion for both genders.
However, significant differences were found between extension and flexion isokinetic
for all parameters.
Table II - Comparisons between weekly muscles
volume training, peak torque and power (see PDF)
Strong and significant correlations was found between parameters
for each concentric movement (extension and extension or flexion and flexion), as
between concentric movements (extension and flexion), as show at tables III and
IV.
Table III - Correlation men group (part 1) (see PDF)
Table III - Correlation men group (part 2) (see PDF)
Table IV - Correlations for woman group (part
1) (see PDF)
Table IV - Correlation woman group (part
2) (see PDF)
Table V shows muscle imbalance between the flexor and extensor
muscles of the knee joint in the assessment at 60o/s (maximus force), although shows
significant major H/Q ratio at 300o/s (resistance force). These findings are below
the recommended minimum for literature that is of 50% [14], emphasizing that these
data are indicated for healthy subjects, and those evaluated in the present study
are trained.
Table V - H/Q ratio for
60o/s and 300o/s isokinect test
*p ≤ 0.01 for t Student
test between H/Q ratio 60o/s and H/Q ratio 300o/s
Training volume performed for each muscle group in resistance
training programs, designed for different adaptations, has been analyzed for many
scientific studies [9,18,19,20,21]. Several studies investigated the result of different
load-volumes in RT for different purposes. The number of exercises, sets, repetitions
and frequency are some of the variables used to control the volume of resistance
training [22-24]. For this reason, to investigate the weekly volume of repetitions
we considered the equation: number of exercises x number of sets x number of repetitions
x number of weekly sessions. The results of cited studies showed a statistically
higher volume of weekly repetitions for the quadriceps muscles compared to the hamstring
muscles.
Considering that
the aim of the present study was to analyze the weekly volume of repetitions for
the quadriceps and hamstrings, and the muscle balance of knee joint extensors and
flexors, the data of our study confirmed the initial hypothesis only to H/Q ratio
for resistance force (300o/s) as a result of equated weekly volume of muscle strength
training for quadriceps and hamstring, but not for maximus force (60o/s) although
our study shows strong and significant correlations between isokinetic parameters
for knee extension and flexion.
Teixeira et al.
[15] quantified the weekly volume of sets for different muscle groups of men and
women aiming muscle hypertrophy. A total of 105 training logs were analyzed, 42
women and 63 men, with at least six months of RT experience. The average weekly
volume of sets for quadriceps (Q) and hamstrings (H) in men was 16 sets and eight
sets respectively, and in women the values were 30 sets for Q and 16 sets for H,
which was different from what was found in our study, since the study cited showed
a difference in training volume between Q and H.
Socio-cultural factors
might, in part explain the reason why people overestimate some muscle groups in
relation to other muscle groups (quadriceps/hamstrings muscles, abdominal muscles/lumbar
muscles), but the biomechanical properties of some muscles and complexity of some
exercises may explain the phenomenon too [15]. Specific hamstring exercises should
be performed to increase strength and reduce muscle imbalance between knee joint
extensors and flexors, reducing the risk of injury like anterior cruciate ligament
injury (ACL) [25].
The H\Q ratio, evaluated
on the isokinetic dynamometer, shows the muscle balance between the (Q) and the
(H), which is extremely useful, for both athletes and nonathletes. At lower speeds
(60-180°/s), the H\Q ratio should be around 60% (or 0.6). Values below 50% (or 0.5)
indicate a severe degree of muscle imbalance [16,26].
A study by Grygorowicz et al. [27] evaluated 48 athletes in the
isokinetic dynamometer test at 60o/s and found an average H/Q ratio of 0.58 in the
group who had no injuries (group A), and a lower H/Q ratio in groups B (mild injuries)
and C (serious injuries). Lee et al. [28] found, for nonathletes, in their
isokinetic dynamometer test at 60o/s, values of the H/Q ratio about 0.56 ± 0.17
in group with injury, and 0.58 ± 0.006 in control group. The average H/Q ratio found
in our study shows a poor H/Q ratio for maximus force (60o/s), and a good H/Q ratio
for resistance force (300o/s), which contradicts the findings of the cited studies
H/Q ratio at 60o/s, and that despite the sample subjects not having knee injuries,
which may be some limitation for this discussion, there was a balance in the weekly
training volume for Q and H muscles, and the H/Q at 60o/s ratio was expected to
be better.
There are some limitations
regarding the use of the H/Q ratio and the risk of injury, since the ratio is done
by using values of concentric action of the extensor muscles in relation to the
flexor muscles, while in sports or daily life activities a concentric action of
extensor muscles is accompanied by an eccentric action of the flexor muscles [28].
In this way, the flexor muscles play a role of braking
the joint movement in different sport-specific motor gestures. Based on the principle
of specificity, eccentric muscle actions for the knee flexors should be included
in RT programs.
One important limitation
of the present study was the fact that the authors had no access to another training
variable such as intervals, weight and intensity of 1RM, and other biomechanics
parameters to knowledge more clear about muscle activity
in training response.
All limitations pointed
can may partially explain the results found in our study, which conflict with the
current and limited literature.
The results demonstrated
no significant difference in the weekly volume of repetitions performed for Q and
H muscles, but a poor H/Q ratio at 60o/s and a good H/Q ratio at 300o/s, which contradicts
the findings of the other studies. Our data contribute to future discussions, and
more studies are needed that can contribute to a better understanding of strength
training programs, with a focus on knee health.
Conflicts of interest
The authors claim to have
no financial or other conflicts of interest (commercial, personal
or political) related to the theme and the development of the article submitted
for publication.
Authors' contributions
Conception and design
of the research: Rodrigues D, Figueira Jr A; Analysis
and interpretation of data: Guedes Jr D, Junior A, Dourado VZ; statistical
analysis: Nogueira HS, Dourado VZ; Writing of the
manuscript: Brugnerotto G, Lima LEM, Nogueira HS; Critical review of the
manuscript for important intellectual content: Silva RP.
Funding source
There was no funding.