Research in Sport Medicine and Technology

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Youth swimming performance may be influenced by anthropometric,
physiology, and biomechanical factors. The purpose of this study was to
analyze the relationships between 50-m front-crawl swimming performance and
relevant anthropometrical (body height, body mass, body mass index, arm
span, shoulders width, thigh, leg and upper arm lengths), muscle architectural
(muscle thickness, pennation angle, and fascicle length) and biomechanical
(stroke rate, stroke length, and stroke index) parameters in male young
swimmers, with 13.86±0.86 years of age (n = 23). Multiple regression analysis
was used to examine the variance of the 50 meters front-crawl. Results indicate
that stroke index, muscle thickness of Vastus Lateralis, and stroke length
explained %89 (p < .01) of 50-m front-crawl swimming performance variability in
these young male swimmers, and stroke index was the best single predictor of
swimming performance (R2=0.519, p<0.001). To conclude, performance of
young male swimmers in the 50 meters front-crawl is determined predominantly
by biomechanical and muscle architectural factors, and must be considered
when predicting success in young swimmers

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The purpose of present study was to investigate the relationship between
Anthropometric characteristics and hip joint flexibility among teenaged girls in
football schools. The population of this study comprised 120 teenaged girls from
football schools of Mashhad. 40 teenaged girls of the population with mean and
standard deviation of age 13/90±0/84 years, weight 51/62±6/51 kg, and height
156/35±4/22 cm as subjects participated. The Anthropometric variables
including calf length, tight length, calf circumference, hip circumference, knee
diameter, pelvic width, and thickness of subcutaneous fat of iliac crest, iliac,
front tight, middle of the calf, range of motion in flexion and extension were
measured. The collected data were analyzed through descriptive statistics and
Pearson correlation coefficient with significant level of p < 0.05. The results
showed that there is a negative and significant relationship between thickness
of subcutaneous fat in front tight, middle of the calf and the range of motion in
hip flexion. However, there is a positive and significant relationship between
pelvic width and the range of motion in hip extension. The results of the present
study demonstrated that there is a relationship between thickness of
subcutaneous fat and pelvic width and hip joint flexibility

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Take-off is the critical phase of the long jump event. The aim of this study was to explore the relationships
between different variables and success in take-off. 37 trials performed by 8 long jumper, participants in
fourth indoor Asian senior athletics championships held in Tehran, with personal best average of 7.68±0.28
meter were recorded at 300 Hz. Five speed-related, five technical and four strength-related variables as well
as an anthropometric variable were measured using motion analysis software. More gain in vertical velocity
and less loss of horizontal velocity are considered as two criteria of take-off success and their relationships
with other variables were determined through correlation and regression analysis. Significant level of 0.05
was set. Some variables of all four groups were significantly correlated with success criteria. These variables
along with some others were entered in regression equations. The results emphasized on dominant role of
the technique and approach velocity and represented the effect of anthropometric characteristics on success
in takeoff. Furthermore eccentric strength of knee extensors was shown as the main strength factor in this
performance.

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 Despite the importance of talent for sports, but it has yet received little attention. The purpose of this study was to present a pattern design for talent identification in  karate based on artificial intelligence algorithms. Subjects divided to adolescent elite karate athletes (n = 19) and non-karate athletes adolescent (n=20) by convenience sampling. Besed on previous literature, we selected and measured biomechanical and anthropometric variables. The normal distribution of all data was analyzed using Shapiro-Wilk test. Principal component Analysis (PCA) was performed to reduce the number of variables and identify the most important anthropometric and biomechanical variables. Then, for modeling, the neural network algorithm was used with three input layer (10 neurons), middle (7 neurons) and output (2 neurons). The results showed the most important anthropometric variables of adolescent elite karate athletes were thoracic subcutaneous fat, height, jump, static balance, grip strength, chest circumference, ankle circumference, abdominal subcutaneous fat and apparent length leg respectively. Also, percentage of correct classification and sensitive of data was high and 87% and 85% respectively. According to the results of this study, this method can be used for talent karate athletes along with other methods.