Introduction
Thigh muscle isokinetic tests are commonly used in top professional soccer players to monitor leg strength values during the training period (1, 3) and to show eventual flexors/extensors (H/Q) muscle imbalances (2), thus to perform individual training modifications trying to prevent musculoskeletal injuries (1).
The aim of the present study was to evaluate thigh muscles isokinetic strength and H/Q ratios in three groups of top level football players, different for age and sport experiences, at the beginning of the season training period. These values can be utilized as reference in case of joint injuries.
Methods
In summer 2013, 42 top level professional football players were tested during the pre-season training: they were divided in three groups of 14 athletes each, according to individual age and sport experience (Table 1).
All players were tested for extensors (quadriceps, Q) and flexors (hamstrings, H) peak torques by a “Prima Iso” isokinetic device (Easytech, Florence, Italy). Concentric tests consisted of 4 repetitions at 90°/s and 20 repetitions at 180°/s.
We considered individual H and Q mean peak torques, the H/Q peak ratios at both speeds and the fatigue indexes (FI) at 180°/s (ratio between first 3 and last 3 movements).
For all statistical comparisons we used Student t-test for paired samples, accepting a value of P<0.05 as significant.
Results
Results are shown in table 1.
All comparisons between dominant and non dominant peak torques were not significantly different in the three groups; in addition, we did not find any significant differences in the comparisons between groups for all mean peak torques, both at 90°/s and at 180°/s, except a slight progressive decrease of the fatigue index from young to senior players in both limbs (S vs U17 P<0.05 for H and Q).
Moreover, all the H/Q ratios were similar in the three groups at both speeds, without any significant age-variation.
Conclusion
The present study showed a symmetric situation in H and Q isokinetic strength in these three groups of high level professional soccer players, without differences between dominant and not-dominant side. Mean peak values were similar to our previous studies (3) and to other papers on professional soccer players (1,2).
In addition, we have found in all athletes the H/Q ratio mean values at about 60-65% values, without any influence of age and sport experience, thus revealing that the three groups of our soccer players did not show evident strength imbalances between H and Q muscles (2), and consequently were probably well trained and at minimal risk of musculoskeletal injuries (1).
Authors:Gilberto Martelli sport medicine doctor, Giovanni Grazzini degree in sport science
In collaboration with: Assist Team, Montecatini Terme; Enervit Virtus Life Center, Poggibonsi, Italy
Published in “Footbal Medicine stategies for joint & ligament injuries”, edited by Roi G.S. Della Villa S., Calzetti e Mariucci, 2014
References
Croisier JL, Ganteaume S, Binet J, Genty M, Ferret JM. Strength imbalances and prevention of hamstring injury in professional soccer players: a prospective study. Am J Sports Med 2008; 36 (8): 1469-1475
Delextrat A, Gregory J, Cohen D. The use of the functional H:Q ratio to assess fatigue in soccer. Int J Sports Med 2010; 31 (3): 192-197
Martelli G, Manetti P, Dainelli S, Grazzini G. Isokinetic seasonal evaluations of professional soccer players. In: Roi GS, Della Villa S (Eds) Football medicine strategies for knee injuries, Calzetti e Mariucci, Perugia, 2012, p. 50
