Isokinetic Knee Muscle Strength Profile in Brazilian Male Soccer,

Futsal and Beach Soccer Players

Claudio de Lira

, Naryana Mascarin

, Valentine Vargas

, Rodrigo Vancini

and Marília Andrade

Faculty of Physical Education and Dance, Federal University of Goiás, Goiânia, Brazil

Department of Physiology, Federal University of São Paulo, São Paulo, Brazil

Center of Physical Education and Sports, Federal University of Espírito Santo, Vitória, Brazil

Keywords: Isokinetic, Performance, Muscle Strength, Soccer, Injury.

Abstract: The main objective of this study was to investigate isokinetic knee muscle strength, hamstring to quadriceps

strength ratio, and bilateral strength deficit in professional futsal, soccer and beach soccer players. We

hypothesized that athletes of different soccer modalities have a specific isokinetic profile due to

physiological, playing surface and biomechanical demands and specificities.

1 INTRODUCTION

Soccer is the most popular sport in the world, with

an estimated 265 million active players (Fifa, 2007).

Performance depends upon a myriad of factors such

as technical, biomechanical, tactical, physiological

and musculoskeletal health condition. Considering

soccer, beach soccer and futsal, the technical and

skills principles behind the games remain the same,

however there are some differences between them,

such as in number of players, number of

substitutions, size of the court and duration of the

match. Thus, athletes of different soccer modalities

can present specific muscle adaptations.

To assess muscular strength profile, isokinetic

testing has been used by clinicians and physical

therapist (Aagaard et al., 1995). Several studies have

been carried out to establish strength profiles in

soccer players (Fousekis et al., 2010). However,

only one study has investigated this situation in

futsal (Reis et al, 2013) while none have been

conducted in beach soccer.

The main objective of this study was to

investigate isokinetic knee muscle strength,

hamstring to quadriceps (H/Q) strength ratio, and

bilateral strength deficit in professional futsal, soccer

and beach soccer players. We hypothesized that

athletes of different soccer modalities have a specific

isokinetic profile due to physiological, playing

surface and biomechanical demands and

specificities.

2 METHODS

This study included 112 professional athletes who

had been playing for at least five years, training

regularly for five sessions per week and had no

history of major lower limb injury or chronic

disease. The sample of volunteers comprised soccer

(n=70) players (19.3±4.8 years, 177.8±7.3 cm and

73.9±8.2 kg), futsal (n=30) (21.3±6.1 years,

175.8±5.3 cm and 72.3±8.8 kg) and beach soccer

(n=12) (29.7±4.4 years, 177.1±6.1 cm and 74.7±6.5

kg). All experimental procedures were approved by

the University Human Research Ethics Committee

(Federal University of São Paulo) and conformed to

the principles outlined in the Declaration of

Helsinki.

To isokinetic assessment, the participants

assumed a seated position on the isokinetic

dynamometer (Biodex Medical Systems Inc.,

Shirley, NY, USA) with their hips flexed at

approximately 85 degrees, and standard stabilization

strapping was placed around the trunk, waist and the

distal femur of the limb being tested in order to

minimize additional movement and ensure the same

conditions for all participants. The parameters

evaluated (for concentric contractions at an angular

speed of 60 degrees/second in dominant and non

dominant limb) were isokinetic absolute hamstring

and quadriceps muscles peak torque (in Nm), H/Q

concentric peak torque ratio in %, and bilateral

strength deficit in %. Peak torque values were

Lira, C., Mascarin, N., Vargas, V., Vancini, R. and Andrade, M.

Isokinetic Knee Muscle Strength Proﬁle in Brazilian Male Soccer, Futsal and Beach Soccer Players.

In Extended Abstracts (icSPORTS 2016), pages 16-18

normalized by body mass (Nm/kg) to enable

comparison with values of other studies, eliminating

the effects of subject heterogeneity as was named in

current study of relative peak torque. The H/Q

strength ratio was calculated by dividing the

maximum torque values of the hamstring by the

maximum torque values of the quadriceps at the

same angular speed and multiplying by 100

(Aagaard et al., 1995). Those athletes that presented

H/Q peak torque ratio below than 60% were

classified with knee imbalance. Bilateral lower limb

muscular strength deficit was calculated by:

[(dominant limb peak torque – non dominant limb

peak torque) / dominant limb peak torque]*100.

Those athletes that presented bilateral strength

deficit higher than 15% were classified as

asymmetric.

All variables presented normal distributions

according to the Kolmogorov-Smirnov test. Data

were expressed as mean and standard deviation. To

evaluate the anthropometric differences among the

three groups, one-way analysis of variance

(ANOVA) was used. To evaluate the influence of

soccer modality and side on isokinetic variables, a

2x3 design side (D versus ND) and sport (soccer

versus futsal versus beach soccer) ANOVA was

used. Newman-Keuls post-hoc procedures were used

to identify specific differences when significant

interactions were present on the ANOVA test. In the

absence of interactions, only main effects were

analyzed. Statistical significance was set at an alpha

of 0.05. All statistical analyses were performed

using the Statistica (version 7.0, Statsoft Inc., Tulsa,

OK, USA) software package.

3 RESULTS

Regarding to the dominant limb, absolute quadriceps

concentric muscle peak torque values of futsal

players (223.9±33.4 Nm) were lower than those of

soccer (250.9±43.0 Nm, p=0.02) and beach soccer

(253.1±32.4 Nm, p=0.03) players, while there were

no significant group differences in flexor muscle

performance (128.6±27.6 Nm vs. 133.1±25.7 Nm

vs. 140.5±11.2 Nm for futsal, soccer and beach

soccer, respectively). Considering the peak torque

values relative to body mass, the same differences

can be seen. Futsal players quadriceps values

(3.1±0.3 Nm/kg) were lower than those of soccer

(3.4±0.4 Nm/kg, p=0.01) and beach soccer (3.4±0.4

Nm/kg, p=0.04) players, while there were no

significant group differences in hamstring muscle

strength (1.8±0.3 Nm/kg vs. 1.8±0.3 Nm/kg vs.

1.9±0.2 Nm/kg for futsal, soccer and beach soccer,

respectively).

Regarding non dominant limbs, absolute and

relative quadriceps concentric peak torque values

were significantly lower in futsal (224.0±35.8 Nm

and 3.1±0.3 Nm/kg, respectively) than in beach

soccer players (256.8±39.8 Nm [p=0.03] and

3.4±0.4 Nm/kg [p=0.04], respectively). There were

also no significant intergroup differences in

hamstring muscle performance for absolute

(124.1±20.1 Nm vs. 127.6±25.0 Nm vs. 136.2±11.4

Nm for futsal, soccer and beach soccer, respectively)

and relative peak torque values (1.7±0.2 Nm/kg vs.

1.7±0.3 Nm/kg vs. 1.8±0.1 Nm/kg for futsal, soccer

and beach soccer, respectively).

Regarding H/Q strength ratios for dominant

(57.6±10.1 % vs. 53.5±8.8 % vs. 56.3±8.4 % for

futsal, soccer and beach soccer, respectively) and

non dominant limbs (55.7±6.8 % vs. 53.2±7.2 % vs.

53.9±7.1 % for futsal, soccer and beach soccer,

respectively), there were no significant differences

between groups for this measure.

Finally, regarding bilateral strength deficit, no

group presented significant difference, neither for

quadriceps nor for hamstring muscles. Futsal players

had deficits of -0.32±9.6% and 1.7±14.5% for

extensors and flexors muscles, respectively. Soccer

players had bilateral deficits of 3.3±11.2% and

4.2±11.5% for extensor and flexor muscles,

respectively. Beach soccer players had bilateral

deficits of -1.7±12.3% and 2.4±11.4% for extensor

and flexor muscles, respectively. Despite means

values were always lower than 15%, some athletes

presented higher bilateral strength deficit.

4 DISCUSSION

Lower strength values for quadriceps muscles in

futsal players could be expected because the match

is played in a restricted space in which the kicks and

passes are performed over shorter distances than in

soccer. Cheung et al. (2012) compared the isokinetic

strength of field (soccer) and court sports players

(basketball and volleyball) and found higher strength

values for soccer players. Comparing the current

results with those of Cheung et al. (2012), we found

higher peak torque relative to body mass values for

the extensor muscles in soccer [present study:

3.4±0.4 Nm/kg versus Cheung et al. (2012):

1.89±0.25 Nm/kg] and court soccer players [present

study: 3.1±0.3 Nm/kg versus Cheung et al. (2012):

1.68±0.24 Nm/kg]. These results are expected since

the soccer volunteers in the present study were

Isokinetic Knee Muscle Strength Proﬁle in Brazilian Male Soccer, Futsal and Beach Soccer Players

professionals while those studied by Cheung et al.

(2012) were drawn from College teams. On the other

hand, our results were similar to those reported in

the study by Ardern et al. (2015) and Ruas et al.

(2015) comparing the peak torque of extensors and

flexors muscles of soccer players.

There were no significant differences in H/Q

ratio among the three groups studied. However, the

three groups presented lower mean values lower

than 60%, which has been traditionally associated

with a higher incidence of knee injuries (Ruas et al.,

2015). An individual data analysis revealed lower

values (≤60%) for dominant limbs in 80% of soccer,

67% of futsal, and 67% of beach soccer players,

which indicate muscle strength imbalance and a

predisposing factor for injury (Ruas et al., 2015).

Therefore, the results highlight the need for

hamstrings strength training program.

In addition to H/Q ratio, muscular bilateral

asymmetry also has been considered a risk factors

for lower limb injuries (Ruas et al., 2015), and it also

may affect sport performance (Young et al., 2002).

In the present study, athletes had low mean values

(<10%) for bilateral deficit. Menzel et al. (2013)

also found low mean values for bilateral peak torque

deficit (9.14±8.65%). Despite the low mean values

of bilateral deficit found in volunteers of the present

study (<10%), individual values ranged from -37%

to 34%. Therefore, the fact that elite soccer, futsal,

and beach soccer players presented symmetrical

strength for the lower limbs does not preclude the

need to conduct individual evaluations for injury

control and prevention.

In sum, H/Q ratio did not differ significantly

among soccer, futsal and beach soccer players, while

extensors muscles were stronger in soccer and beach

soccer players. In the three soccer modalities, mean

values for H/Q ratio were lower than the

recommended literature values. Thus, strength

prevention programs for hamstring muscles can be

useful to improve H/Q ratio. In addition, beach

soccer is a relatively new sport for which no national

professional leagues exist in many countries. Thus,

future studies investigating other characteristics of

beach soccer players, such as physiological response

to exercise, are warranted.

ACKNOWLEDGEMENTS

We would like to thank all the athletes who

volunteered their time to participate in this study and

the Olympic Center of Training and Research, São

Paulo, Brazil. This work was supported by the

Financiadora de Estudos e Projetos/Brazilian

Science and Technology Ministry (FINEP-MCT-

Brazil), the Brazilian Sports Ministry and Fundação

de Amparo à Pesquisa do Estado de Goiás (FAPEG,

Brazil).

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icSPORTS 2016 - 4th International Congress on Sport Sciences Research and Technology Support