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A comparison of muscle strength and flexibility between the preferred and non-preferred leg in English soccer players

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Jinsheng Liu

on 15 June 2015

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Transcript of A comparison of muscle strength and flexibility between the preferred and non-preferred leg in English soccer players

Musculoskeletal abnormality
Musculoskeletal abnormality was defined as a contralateral strength imbalance greater
than 10% (Wyatt and Edwards 1981, Grace et al. 1984).
1.Early studies have shown that a bilateral leg strength difference of 10% or greater may be a contributing factor to injury.
Results - Hamstring/quadriceps ratio
No significant differences (P > 0.05) between the preferred and the non-preferred leg were found in the hamstring/quadriceps ratio at angular velocities of 1.05, 2.09 and 5.23 rad/s in the concentric mode.
Participants
Forty-one elite and sub-elite soccer players were studied (age 23.4 +/- 3.8 years; height 1.81 +/- 0.06 m; body mass 81.7 +/- 9.9 kg). Data are presented as mean +/- SD. Participants recruited were not injured or rehabilitating from injury at the time of testing.
Results - Hip joint flexibility
Introduction
Discussion
Results - Muscle Strength
A comparison of muscle strength and flexibility between the preferred and non-preferred leg in English soccer players
Liu Jinsheng
MG1407032

2.Although most soccer players favor one particular foot for kicking the ball, it is not known whether this preference causes an asymmetry in the strength and flexibility of the lower extremities.
3.This study was designed to determine whether asymmetry between the preferred and non-preferred kicking leg is present in the lower limb strength and flexibility of soccer players.
Elite players were classed as those who were signed for a professional club and played international soccer (full-time professional players with an English Premier League club). Sub-elite players were classed as those who were not signed for a professional club but were playing regularly for local and university teams.
Measurements for each participant were in two categories:

muscle strength
profiling of the knee flexors and knee extensors, and
flexibility
in hip flexion.
Strength of knee flexors (hamstrings) and knee extensors (quadriceps) in both the preferred and non-preferred legs was measured using an isokinetic dynamometer (Lido Active, Loredan, Davis, CA).
Each participant visited the laboratory and was tested with the same protocol on
two
separate occasions. The first visit entailed
familiarization
with the dynamometer and the experimental procedure, and in the second session the following procedure was
administered
.
No significant differences were found in knee extensor muscle strength between the preferred and the non-preferred leg at any of the angular velocities tested.

For the knee flexors, a significant difference was found between the preferred and non-preferred leg at 2.09 rad/s during concentric muscle actions (119 +/- 22 versus 126+/-24 Nm, t40=2.73, P < 0.05) with the preferred leg being weaker than the non- preferred leg.
No significant differences were found for other angular velocities.
A significant difference was found between the preferred and the non-preferred leg for the DCR (0.79+/-0.13 versus 0.84+/-0.16, t40 = 2.34, P < 0.05) .
Strength Measurements
Flexibility
The flexibility of the participant’s hip joint (in flexion) was measured using a goniometer (MIE Goniometer, Medical Research Ltd, Leeds). The subject lay supine on the floor with the legs extended and the head on the floor.
Results - Fast/slow speed ratio
No significant differences (P > 0.05) were found in the fast/slow speed ratios of the preferred and the non-preferred leg for either the knee extensors (0.59 +/- 0.05 versus 0.60 +/- 0.05, P > 0.05) or the knee flexors (0.78 +/- 0.1 versus 0.77 +/- 0.1, P > 0.05).
No significant differences were found between the mean hip joint flexibility of the preferred and the non-preferred leg (90.4 degree +/- 11.6 degree versus 90.9 degree +/- 13 degree, P > 0.05).
Musculoskeletal abnormality
In this study, 28 of 41 players (68%) were found to have at least one musculoskeletal abnormality which consisted of a contralateral strength imbalance of greater than 10% in one or more specific muscle groups.
1.All the players favoured one foot in kicking and receiving the ball. This preference did not affect lower extremity flexibility but it did affect lower extremity strength.
2.A possible explanation for the
difference in muscle strength
is that, during kicking, the knee of the non-preferred (i.e. support) limb is bent so that its flexor muscles help to stabilize the joints, support the weight of the body and resist the reaction of the torque developed by the opposite limb.
3.In contrast, during kicking by the preferred leg,
knee flexor activity
needs to be minimized so as to allow the knee to extend rapidly as it makes contact with the ball.
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