Hamstrings‐to‐quadriceps strength and size ratios of male professional soccer players with muscle imbalance

Abstract

The aim of this study was to determine the correlation between the concentric hamstrings/quadriceps muscle strength (Hcon :Qcon ) and cross-sectional area ratios (Hcsa :Qcsa ) in professional soccer players with Hcon :Qcon imbalance. Nine male professional soccer players (25·3 ± 4·1 years) performed five maximal concentric contractions of the knee extensors (KE) and flexors (KF) at 60 s(-1) to assess Hcon :Qcon . The test was performed using the dominant (preferred kicking), and non-dominant limb with a 5-min recovery period was allowed between them. Only players with Hcon :Qcon < 0·60 (range: 0·45-0·59) in both limbs were included in this study. The muscle cross-sectional area (CSA) of KE and KF was determined by magnetic resonance imaging. The correlations between Hcon :Qcon and Hcsa :Qcsa in the dominant leg (r = -0·33), non-dominant leg (r = 0·19) and in the both legs combined (r = 0·28) were not statistically significant (P>0·05). Thus, the Hcon :Qcon seems not to be determined by Hcsa :Qcsa in professional soccer players with Hcon :Qcon imbalance.

Knee Extension Strength and Hamstrings-to-Quadriceps Imbalances in Elite Soccer Players

“…Considering the increasing demand for high levels of strength and power in professional soccer, which involves a high number of sprints, high speed kicks, jumps, changes of direction and other power activities [34], it is expected that the elite level players should have high knee extensor and flexor muscle strength, as well as a favorable H:Q ratio to support both performance and knee stability. The conventional H:Q ratio measured at an angular velocity of 60 ° • s − 1 in elite soccer players has been reported in a number of older [11,19] and more recent studies [6,10,13,28,33] and has been used as a criterion for muscle imbalance around the knee joint. The average values of the conventional H:Q strength ratio range from 57-62 % [6,10,28,33], while H:Q ratios below 45 % [11,12] or below 60 % [6,9,13,26] have been utilized as cutoff values for identifying muscle imbalances, which may increase the likelihood of hamstrings injury more than 4 fold, compared with players with normal H:Q ratios [12].…”

“…The conventional H:Q ratio measured at an angular velocity of 60 ° • s − 1 in elite soccer players has been reported in a number of older [11,19] and more recent studies [6,10,13,28,33] and has been used as a criterion for muscle imbalance around the knee joint. The average values of the conventional H:Q strength ratio range from 57-62 % [6,10,28,33], while H:Q ratios below 45 % [11,12] or below 60 % [6,9,13,26] have been utilized as cutoff values for identifying muscle imbalances, which may increase the likelihood of hamstrings injury more than 4 fold, compared with players with normal H:Q ratios [12]. Epidemiological studies have demonstrated that a high degree of muscular imbalance is associated with knee and low-back injuries, accounting for 12 % of hamstring strains over a 2-season medical survey in football clubs of English Premier and Football leagues [15,36].…”

“…However, both conventional and functional H:Q ratios were similar in division 1 and division 2 players, making it unclear to conclude whether soccer training and match play at a professional level results in greater increases in strength in knee extensors or knee flexor muscles. Interestingly, very recent data from professional players suggest that players with a low H:Q ratio may have a higher quadriceps peak torque measured at an angular velocity of 60 ° • s − 1 , compared with players with higher H:Q [13,18]. For example, Denadai et al [13] selected injury-free professional soccer players on the basis of a low H:Q ratio (53 ± 4 %) in order to study its relationship with muscle cross-sectional area.…”

“…Interestingly, very recent data from professional players suggest that players with a low H:Q ratio may have a higher quadriceps peak torque measured at an angular velocity of 60 ° • s − 1 , compared with players with higher H:Q [13,18]. For example, Denadai et al [13] selected injury-free professional soccer players on the basis of a low H:Q ratio (53 ± 4 %) in order to study its relationship with muscle cross-sectional area. Peak torque of the knee extensors was very high compared to the reported average values for professional players, while knee flexion strength was within the normal values and could not be characterized as low [13].…”

The functional significance of hamstrings composition: is it really a “fast” muscle group?

“…While the influence of hamstrings muscle composition on function in vivo remains to be elucidated, muscle size has been consistently found to be a substantial determinant of isometric strength in various muscles (e.g., elbow flexors, r = 0.81, Erskine et al., ; plantar flexors, r = 0.65, Bamman et al., ; knee extensors, r = 0.59, Maughan et al., ). Considering the hamstrings, the four studies we are aware of reported quite diverse relationships between muscle size and isometric/concentric strength measures ( r = −0.22 to 0.80; Kanehisa et al., ; Masuda et al., ; Akagi et al., ; Denadai et al., ). However, none of these studies examined eccentric or explosive strength.…”