scholarly journals Bilateral and Unilateral Asymmetries of Isokinetic Strength and Flexibility in Male Young Professional Soccer Players

2013 ◽  
Vol 36 (1) ◽  
pp. 45-53 ◽  
Author(s):  
Abdolhamid Daneshjoo ◽  
Nader Rahnama ◽  
Abdul Halim Mokhtar ◽  
Ashril Yusof

This study investigated bilateral and unilateral asymmetries of strength and flexibility in male young professional soccer players. Thirty-six soccer players (age: 18.9 ± 1.4 years) participated in this study. A Biodex Isokinetic Dynamometer was used to assess the hamstring and quadriceps strength at selected speeds of 60°/s, 180°/s and 300°/s. Hip joint flexibility was measured using a goniometer. No difference was observed in conventional strength ratio, dynamic control ratio and fast/slow speed ratio between the dominant and non-dominant legs (p>0.05). All but one of the players (97.2%) had musculoskeletal abnormality (bilateral imbalance > 10%) in one or more specific muscle groups. The dominant leg had greater hip joint flexibility compared with the non-dominant leg (108.8 ± 10.7° versus 104.6 ± 9.8°, respectively). The findings support the hypothesis that physical performance and movement pattern experienced during soccer playing may negatively change the balance of strength in both legs (bilateral strength balance), but not on the same leg of the young male professional soccer players. The results can be helpful for trainers and coaches to decide whether the players need to improve their balance and strength which in turn may prevent injury. It is suggested that in professional soccer training, quadriceps and hamstrings muscle strength, as well as hip joint flexibility should not be overlooked.

2013 ◽  
Vol 39 (1) ◽  
pp. 115-125 ◽  
Author(s):  
Abdolhamid Daneshjoo ◽  
Nader Rahnama ◽  
Abdul Halim Mokhtar ◽  
Ashril Yusof

Abstract Muscular strength is an important factor which is crucial for performance and injury prevention in most sports. The purpose of this study was to evaluate the effects of the FIFA’s Medical Assessment and Research Centre 11+ and HarmoKnee injury prevention programs on knee strength of young professional male soccer players. Thirty-six soccer players (age: 18.9 ± 1.4 years) were divided equally into three groups; the 11+, HarmoKnee and control groups. The programs were performed for 24 sessions. Hamstring and quadriceps strength was measured using the Biodex System 3 at 30°, 60° and 90° of knee flexion. The 11+ increased quadriceps strength in the dominant leg by 19.7% and 47.8% at 60°and 90° knee flexion, respectively, and in the non-dominant leg by 16%, 35.3% and 78.1 % at 30°, 60° and 90° knee flexion, respectively. The HarmoKnee group, however, showed increased quadriceps strength only at 90° i.e., by 85.7% in the dominant leg and 73.8% in the non-dominant leg. As for hamstring strength, only the 11+ group demonstrated an increment by 24.8% and 19.8% at 30° and 60° knee flexion in the dominant leg, and in the nondominant leg, by 28.7% and 13.7% at 30° and 60° knee flexion, respectively. In conclusion, both warm-up programs improve quadriceps strength. The 11+ demonstrated improvement in hamstring strength while the HarmoKnee program did not indicate any improvement. We suggest adding eccentric hamstring components such as Nordic hamstring exercise to the HarmoKnee program in order to enhance hamstring strength.


Cartilage ◽  
2020 ◽  
pp. 194760352092477
Author(s):  
Hanna Schenk ◽  
David Simon ◽  
Leonie Waldenmeier ◽  
Christoph Evers ◽  
Rolf Janka ◽  
...  

Purpose. The study aims to detect regions at risk for (pre-)osteoarthritis in the tibiofemoral joint of young professional soccer players by evaluating cartilage composition by T2 mapping in a 3 T magnetic resonance imaging setting. Methods. In this longitudinal study, 20 professional adolescent soccer players were included. Tibiofemoral cartilage was assessed by quantitative T2 mapping and T2 values were evaluated by regions of interest analysis. Statistical evaluation, using Wilcoxon signed-rank tests, was performed to compare global T2 values and subregional T2 values between a baseline and a follow-up investigation 4.3 years later. Based on the average of playing time (15 years) we divided the cohort in 2 groups and differences were evaluated. Results. When comparing baseline and follow-up, our findings showed statistically significant increases of the global medial tibial and femoral T2 values. The most noticeable results of the subregional T2 analysis were statistically significant increases in the medial posterior zones (deep femoral 36.1 vs. 39.5, P = 0.001; superficial femoral 57.0 vs. 62.4, P = 0.034; deep tibial 28.3 vs. 34.1, P = 0.009; superficial tibial 43.2 vs. 55.3, P = 0.002). Conclusion. The elevation of T2 values in the medial, especially medial posterior, compartment of the knee joint indicates that these regions are at risk for early cartilage degeneration already at the time of adolescence. The findings can help individualize and optimize training concepts and to be aware of the chronic stress on these vulnerable areas. Prevention programs should be established in young players to avoid further cartilage damage.


Author(s):  
Hadi Nobari ◽  
Jason M Cholewa ◽  
Alfonso Castillo-Rodríguez ◽  
Mehdi Kargarfard ◽  
Jorge Pérez-Gómez

Abstract Objective Various nutritional strategies are adopted for athletes to maintain and to improve performance during the competition season. Betaine may enhance performance during a competitive season by increasing the testosterone to cortisol ratio and reducing systemic inflammation. The aim of this study was to investigate the effect of betaine supplementation on the bio-motor abilities in young professional soccer players. Methods Twenty-nine young professional soccer players (age, 15.5±0.3 years) were matched by position and randomly assigned to one of two groups for 14 weeks: betaine (BG, 2 g/day; n=14) or placebo (PG n=15). Diet was standardized by a nutritionist, and measures of muscular power (countermovement jump: CMJ), change of direction: modified 5-0-5), acceleration (10 m sprint), sprint performance (30 m sprint time: SpT), muscular strength (leg press and bench press one repetition maximum: 1-RM), repeated sprint ability (running-based anaerobic sprint test: RAST), and aerobic capacity (30-15 intermittent fitness test) were assessed in the pre (P1), mid (P2) and post (P3) season over the course of 5 days. All subjects participated in one soccer match and five training sessions per week. Results Significant (p < 0.05) group x time interactions were found for maximal oxygen uptake (VO2max), anaerobic peak power, and muscular strength favoring BG at P2 and P3 compared to P1. There were meaningful (p < 0.05) group x time interactions for CMJ, SpT, and peak power during the RAST that favored the BG. Conclusions 14-week of betaine supplementation increased predicted 1-RM, VO2max, and repeated sprint ability performance in youth professional soccer players. Betaine supplementation seems to be a useful nutritional strategy to improve and to maintain performance during a competitive soccer season.


2019 ◽  
Vol 10 ◽  
Author(s):  
Cristina Petisco ◽  
Rodrigo Ramirez-Campillo ◽  
Daniel Hernández ◽  
Oliver Gonzalo-Skok ◽  
Fabio Y. Nakamura ◽  
...  

Kinesiology ◽  
2017 ◽  
Vol 49 (2) ◽  
pp. 153-160 ◽  
Author(s):  
Asier Los Arcos ◽  
Javier Yanci

The aim of this study was to examine the association of perceived respiratory and muscular exertions and associated training load (TL) for monitoring changes in several aerobic fitness and neuromuscular performance parameters during 32 weeks of soccer training in young professional players. Twenty male soccer players (age=20.6±1.8 years, body height=1.80±.06 m, body mass=73.6±6.7 kg) belonging to the same reserve team of a Spanish La Liga Club participated in this study. Countermovement jump (CMJ), CMJ with arm swing, linear sprint running (over 5 m and 15 m) and an aerobic fitness running test were performed at the start of the pre-season (Test 1) and 32 weeks later (Test 2). During these eight months, after each training session and match, players rated their perceived exertion (sRPE) separately for respiratory (sRPEres) and leg musculature (sRPEmus) effort. Training load was calculated by multiplying the sRPE value by the duration of each training session or match. Accumulated training and match volume (i.e., time) and associated respiratory and muscular training loads were negatively correlated with the changes in aerobic&nbsp;fitness performance after 32 weeks of training (r=-.53/-.62). In addition, accumulated perceived respiratory load was negatively correlated with the changes in 15 m sprint performance (r=-.51/-.53). A high practice volume (time) and associated respiratory and leg muscular TL can impair the long-term improvement of aerobic fitness and sprint performance in professional soccer players.


2013 ◽  
Vol 2013 ◽  
pp. 1-9 ◽  
Author(s):  
J. Taradaj ◽  
T. Halski ◽  
M. Kucharzewski ◽  
K. Walewicz ◽  
A. Smykla ◽  
...  

The aim of this study was to assess the clinical efficacy and safety of NMES program applied in male soccer players (after ACL reconstruction) on the quadriceps muscle. The 80 participants (NMES = 40, control = 40) received an exercise program, including three sessions weekly. The individuals in NMES group additionally received neuromuscular electrical stimulation procedures on both right and left quadriceps (biphasic symmetric rectangular pulses, frequency of impulses: 2500 Hz, and train of pulses frequency: 50 Hz) three times daily (3 hours of break between treatments), 3 days a week, for one month. The tensometry, muscle circumference, and goniometry pendulum test (follow-up after 1 and 3 months) were applied. The results of this study show that NMES (in presented parameters in experiment) is useful for strengthening the quadriceps muscle in soccer athletes. There is an evidence of the benefit of the NMES in restoring quadriceps muscle mass and strength of soccer players. In our study the neuromuscular electrical stimulation appeared to be safe for biomechanics of knee joint. The pathological changes in knee function were not observed. This trial is registered with Australian and New Zealand Clinical Trials RegistryACTRN12613001168741.


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