Hayri Ertan

Muscular activation patterns of the bow arm in recurve archery

In archery shooting, the archer should hold the bow in place using only the pressure produced through drawing back the bowstring. Most coaches discourage the archer from gripping the bow as this is believed to produce a sideways deflecting torque on the bow and arrow during the release. The purpose of this study was to compare the bow hand forearm muscular activation patterns of elite archers with beginners to define the muscular contraction-relaxation strategies in the bow hand forearm muscles during archery shooting and investigate the effects of performance level on these strategies. Electromyographic activity of the M. flexor digitorum superficialis and the M. extensor digitorum of 10 elite and 10 beginner archers were recorded together with a pulse synchronized with the clicker snap. Raw electromyographic records as 1s before and after the clicker pulse were rectified, integrated, and normalized. The data was then averaged for successive shots of each subject and later for both groups of archers. The main difference between the elite and beginner archers was that the elite archers had a greater activation of the M. extensor digitorum, which indicates that they avoid gripping the bow-handle not only relaxing the flexor muscles, but also contracting the extensor muscle groups. This muscular contraction strategy secures the archer to not interfere with the forward movement of the bow, which is the forward acceleration of the bow caused by the pushing power of the bowstring.

Activation of Selected Ankle Muscles During Exercises Performed on Rigid and Compliant Balance Platforms

STUDY DESIGN Experimental laboratory study. OBJECTIVE To compare how the design of 2 balance platforms affects ankle musculature activation for various weight-bearing exercises. BACKGROUND Balance platforms are widely used in both training and rehabilitation, and a better understanding of how platform design and type of exercise modify the demands on the ankle musculature may be helpful in staging exercise progression. METHODS Surface electromyography was used to measure the activation level of the fibularis longus, tibialis anterior, and medial gastrocnemius while performing 4 exercises on 2 different balance platforms (compliant and rigid). Twenty-four (12 females, 12 males) healthy, sedentary subjects participated in the study. Analysis of variance was used for statistical analysis. RESULTS There was no significant interaction between balance platforms and exercises (P>.05), and the type of platform did not influence muscle activation for the 3 muscles monitored (P>.05). The highest activation level for the fibularis longus and medial gastrocnemius was obtained during single-leg stance, and for the tibialis anterior during the single-leg squat (P<.05). CONCLUSION In this study, although the demands on the ankle musculature were similar for selected exercises performed on a compliant versus a rigid balance platform, muscle activation level varied based on the exercise.

The Effect of Kick Type on the Relationship between Kicking Leg Muscle Activation and Ball Velocity

This study aimed to identify the effects of different kick types on the relationship between kicking leg muscle activation and ball velocity. The muscle activation of selected knee extensor and flexor muscles of 10 amateur soccer players were measured using electromyography during the performance of six maximal soccer kick types. The highest ball velocity was achieved by the instep kick (96.2 km/hr-1), followed by the lofted kick, the inside curve kick, the outside kick, the outside curve kick, and finally the inside kick (81.3 km/hr-1). There were significant positive correlations between muscle activation and ball velocity for the vastus lateralis and lofted (0.765), inside curve (0.792) and instep kicks (0.788), and for the gastrocnemious with the outside kick (0.796). Non-significant correlations between muscle activation and ball velocity exhibited a trend such that they were positive for the vastus medialis and vastus lateralis but negative for the biceps femoris and gastrocnemious for inside-foot-dominated kicks, while this trend was reversed for outside-foot-dominated kicks. According to results, the noted trends can be explained by the change in muscle activation patterns required to orientate the foot for each type of kick; this has implications for players’ training activities.

The Effects of Whole Body Vibration Treatments on Lower Body Muscular Activity in Well-Trained Athletes from Different Sports Branches

A limited number of acute whole body vibration (WBV) studies have investigated the effects of WBV treatments which were applied with different vibration frequencies and amplitude combinations on lower extremity muscle activation of well-trained athletes from different sports branches. To compare the effects of WBV on lower extremity muscle activation via Surface Electromyography (sEMG) of well-trained athletes from different sports branches (soccer, basketball and swimming) during static and dynamic squat exercises. sEMG activities of Tibialis Anterior (TA), Gastrocnemius Medialis (GM), Vastus Medialis (VM), Rectus Femoris (RF), Vastus Lateralis (VL) and Biceps Femoris (BF) muscles of 7 male soccer players, 7 male basketball players, and 6 male swimmers were recorded during WBV applied in static squat and dynamic squat positions with different frequencies (30-35-40 Hz) and amplitude (2-4 mm) combinations separated from each other by 5 min passive rest periods. Each combination was applied for 30 sec. The highest muscle activation was determined in TA of the swimmers compared to soccer players during static squat with 4mm-30Hz WBV application (p=0.027). The lowest muscle activation was also determined in VL of the swimmers compared to soccer players during static squat with 2mm-40Hz WBV (p=0.049). During dynamic squat with 4mm-40Hz WBV, the highest muscle activity was determined in RF of the basketball players compared to swimmers (p=0.030). However, dynamic squat with 2mm-40Hz WBV application gave rise to the lowest muscle activation in VL of the basketball players compared to soccer players (p=0.042). Well-trained athletes from different sports branches demonstrated different neuromuscular responses to acute WBV treatments. WBV during dynamic squatting which was applied with 4mm-40 Hz may be more beneficial in enhancing neuromuscular performance acutely for well-trained male athletes since it resulted in higher levels of muscular activation responses according to the present study.

The Relationship Between Anthropometric, Physical, Technique Components and Three Different Agility Tasks in Soccer Players

Objective: This study was aimed to investigate the relationship between anthropometric, physical, technique components and three agility tasks; planned (PAT), unplanned (UNAT) and unplanned soccer specific reactive agility test (USRAT). Eighteen sub-elite soccer players (age 18±1.28 years) attended to the this study. Material and Methods: Anthropometric measurements, linear sprint speed tests (10m static sprint, flying 20m sprint), leg muscle strength tests (depth jump, isokinetic strength test), and running technique tests (zig-zag test) were performed. Planned agility, unplanned agility and agility with one unplanned change of direction with dribbling were used to evaluate agility performances. To investigate the relationship between PAT, UNAT, USRAT and anthropometric, physical, technique components; Pearson or Spearman correlation analysis were used depending on normal distribution. Results: Static 10m sprint and PAT showed a statistically significant correlation (r=0.604). UNAT was significantly correlated to flying 20 m test (r=0.513). None of drop jumps components had significant correlations with the agility tests (p>0,05). Moreover, USRAT showed statistically significant correlation (r=-0.502), (p<0.05) with the number of steps taken at the turn movement and no significant relationship with isokinetic variables (p>0.05). Conclusion: In conclusion, if a soccer-specific task is involved in an agility test, it may be reported that the performance is most likely to be affected by player’s technical skill. Moreover, the results of running technique analysis indicate that to be better at agility task players have to be better at making decisions instead of getting closer to the ground at the turning movement.