Força muscular e índice de fadiga dos extensores e flexores do joelho de jogadores profissionais de futebol de acordo com o posicionamento em campo

Peak torque angle, acceleration time and time to peak torque as additional parameters extracted from isokinetic test in professional soccer players: a cross-sectional study

This study investigated additional and traditional variables from isokinetic test of thigh muscles in soccer players across different field positions. One hundred and eighty-nine athletes performed maximal concentric isokinetic knee contractions on dominant (DL) and non-dominant limb (NDL) at 60º/s and 240º/s. The additional outcomes peak torque angle (AngPT), acceleration time (AcT) and time to peak torque (TPT) and traditional outcomes Peak torque (PT), total work (TW) and power (Pw) were extracted from the exam. Goalkeepers (GK), side backs (SB), central backs (CB), central defender midfielders (CDM), central attacking midfielders (CAM) and forwards (FW) were considered. Comparisons between limbs and positions demonstrated that SB extensors of the DL presented TPT lower (p = 0.006) and AngPT higher (p = 0.011) than NDL at 60°/s. CDM extensors of the DL showed lower TPT at 60°/s (p = 0.003) and 240°/s (p = 0.024). CAM flexors of the DL showed lower TPT (p = 0.026) and AcT (p = 0.021) at 240°/s than NDL. CB, CDM and CAM extensors of the NDL showed higher PT, TW and Pw than DL (p < 0.05). In conclusion, there are muscle imbalances between limbs in SB, CDM and CAM and across different field positions.

Championship interseason period did not reduce knee peak moment: A 10-years retrospective study of 467 elite soccer players

Study aim: To compare knee moment profiles of professional soccer players from different playing positions before and after an interseason period.

Material and methods: Retrospective study of 467 healthy, professional elite Brazilian soccer players before and after an official championship interseason period during 10-years. Main outcome measures were isokinetic peak moment from knee extensors and flexors from concentric and eccentric contractions. A Two-way ANOVA analysis was used to compare each playing position before and after interseason period.

Results: It was found no statistical difference in Ext.CPT (from p = 0.11 to p = 0.97), Ext.EPT (from p = 0.07 to p = 0.85), Flx. CPT (from p = 0.14 to p = 0.90) or Flx.EPT (from p = 0.10 to p = 0.91) between End-Season and Pre-Season evaluations for all playing positions (from Goalkeepers, Defenders, Backsiders, Midfielders and Forwards).

Conclusions: Isokinetic peak moment did not have significant differences after an interseason period of 4 to 6 weeks, allowing trainers and coaches to focus their pre-season period on other performance concerns than strengthening.

TORQUE, POWER AND FATIGUE RATIO IN KNEE FLEXORS AND EXTENSORS OF SOCCER PLAYERS

ABSTRACT Introduction: Soccer is the most popular and practiced sport in the world and is characterized by high intensity movements. This high demand induces several types of locomotor system injury, and one of the intrinsic factors responsible for triggering these injuries is muscle imbalances, which can occur between limbs or between muscles groups of the same limb. Objective: To evaluate the muscular performance between knee flexor/extensor groups of both limbs in professional soccer athletes.: Methods: Isokinetic assessments were performed in 18 professional soccer athletes, with mean age of 26.9 ± 3.6 years and mean body mass index (BMI) of 23.9 ± 1.7 kg/m2.. The test protocol consisted of five concentric contractions of knee flexion and extension at angular velocity of 60o/sec, 15 contractions at 180o/sec and 30 contractions at 300o/sec in both limbs. Test paired t-test was used to verify the torque, power, and fatigue ratio of flexors and extensors of the dominant and non-dominant knee. Results: There was no significant difference between the evaluated members related to dominance (p>0.05). Regarding the torque ratio between flexors and extensors, we observed values below what is considered normal for this population, besides a higher fatigue index in knee flexor group when compared with the extensor group. Conclusion: No better performance was observed in the dominant limb, suggesting that, although this limb is preferred, this does not necessarily characterizes the better performance. The data also revealed an imbalance in the torque production capacity between the knee flexor and extensor groups, with an unfavorable ratio for the hamstrings, as well as a higher fatigue index in this group, which would make these muscles more susceptible to injures. Level of Evidence II; Diagnostic studies - Investigating a diagnostic test.