Research in Sport Medicine and Technology

Background and Aims: Archery is a precision sport that requires postural stability and control of hand tremor during aiming. Hand tremor, which manifests as involuntary movements, can lead to a decline in sports performance. The aim of this study was to investigate the relationship between the amplitude and frequency of hand tremor and shooting accuracy in amateur recurve archers.
Materials and Methods: This semi-experimental study was conducted on 12 novice recurve archers (aged 18 years and older). Participants performed a simulated competition test consisting of 60 arrows shot at a distance of 18 meters. Hand tremor at the elbow and wrist joints of both hands was recorded during the aiming phase using a six-camera 3D motion analysis system. The recorded motion data were processed using Fast Fourier Transform (FFT) in MATLAB software. Based on the output of this analysis, indices such as peak frequency and median power frequency were calculated to examine frequency components, and RMS was computed to assess tremor amplitude. Finally, shooting accuracy and tremor parameters were analyzed using Pearson correlation coefficient.
Results: The results showed that tremor amplitude, particularly in the right hand, was significantly associated with lower accuracy. Additionally, higher-frequency tremors in both hands were directly associated with better archery performance.
Conclusion: The findings of this study demonstrated significant associations between hand tremor characteristics and shooting accuracy in amateur recurve archers. These findings may contribute to a better understanding of performance stability and may be useful in the development of training and performance-monitoring strategies in archery.

Although hip muscle strengthening has been reported as an effective way to decrease PFPS symptoms, however its effect on lower extremity kinematics is less clear. The current study was done with the aim of investigating the effect of hip abductor and external rotator muscles strengthening exercises on lower extremity kinematics in static and dynamic states. In a randomized controlled trial, 33 patients with patellofemoral pain (PFP) were randomly assigned into exercise (8 female, 30±6.8 y/o, 23.8±2.6 BMI and 8 male, 31.2±7 y/o, 25.6±1.5 BMI) and control (9 female, 29.9±7.3 y/o, 23.2±3.2 BMI and 8 male, 32±6 y/o, 25.5±1.9 BMI) groups. In exercise group they received hip abductor and external rotator strengthening exercises by thera-band 3 times per week for 12 weeks under supervision by a physiotherapist. The control group did not receive any training intervention. Hip muscles strength and kinematics in static and dynamic states, were assessed at baseline and post-intervention. Repeated measures ANOVA by using SPSS were applied to assess the effects of the exercise on measured variables (α=0/05). After 12 weeks of strengthening program, by an increase in abductor muscle strength in women from 19.6 to 26.4 %BW (P=0.000) and in men from 29.9 to 38.1 %BW (P=0.003), and in hip external rotator muscles in women from 13.2 to 16.9 %BW (P=0.024) and in men from 26.3 to 34.9 %BW (P=0.000), dynamic knee valgus angle during single-legged squat improved in women from 170 to 174.6 degrees (P=0.018) and in men from 171.8 to 176.8 degrees (P=0.017) and contralateral pelvic drop angle during stair descending improved only in women from 7.9 to 6 degrees (P=0.04) in the exercise group. No significant difference was observed at quadriceps angle (P≥0.05). The findings suggest that hip muscles strengthening can alter the lower extremity kinematics, in dynamic state, at the frontal plane, and it might be said that due to these changes following hip abductor and external rotator muscles strengthening exercises by thera-band, the symptoms of PFP improve more consistent.