scholarly journals Body Composition and Kinematic Analysis of the Grab Start in Youth Swimmers

2014 ◽  
Vol 42 (1) ◽  
pp. 15-26 ◽  
Author(s):  
Ahmet Alptekin
Keyword(s):  
Body Composition ◽  
Vertical Velocity ◽  
Center Of Mass ◽  
Random Order ◽  
Horizontal Displacement ◽  
Vertical Displacement ◽  
Kinematic Parameters ◽  
Total Distance ◽  
Block Time ◽  
The Relationship

Abstract The purposes of this study were to compare the kinematic variables in youth swimmers during the grab start between sexes and to investigate the relationship between body composition and kinematic variables of the participants. Six female (Mage = 13.71 ± 0.49 yrs) and seven male (Mage = 14.00 ± 1.07 yrs) swimmers participated in this study. All participants were required to perform grab start tests in random order (three trials by each participant), while the best attempt was analyzed. Nineteen kinematic parameters consisting of block time, flight time, flight distance, total time, total distance, horizontal and vertical displacement of the center of mass (CM) at take-off, horizontal and vertical displacement of the CM at entry, height of take-off and entry, relative height of take-off, horizontal and vertical velocity of the CM at take-off, horizontal and vertical velocity of the CM at entry, angle of take-off, angle of entry and angle of knee at block were analyzed. Out of the 19 evaluated kinematic parameters, a statistical difference between the female and male group was found only in the total distance. Therefore, both female and male groups are considered as only one group and merged after analyzing the results. Statistical analysis showed positive and negative correlations between horizontal / vertical velocity of CM at take-off and several kinematic variables (e.g. angle of entry (rhorizontal = -.868, p=.000 / rvertical = .591, p=.02), total distance (rhorizontal = .594, p=.02 / rvertical = .54, p=.04), and height of take-off (rvertical = .888, p=.000), respectively). On the other hand, positive and negative correlations were found between somatotype components and several kinematic variables (e.g. horizontal displacement of CM at entry (rendomorphy = -.626, p=.013), angle of entry (rmesomorphy = -.686, p=.005 / rectomorphy = .52, p=.047), total distance (rendomorphy = -.626, p=.012), and height of take-off (rendomorphy = -.633, p=.011 / rectomorphy = .515, p=.05)). In conclusion, results show that in order to be successful at grab start performance, a swimmer should target to get higher horizontal velocity of CM at take-off and optimize the angle of take-off so this movement form supplies more total distance to the swimmer. Coaches should consider improving start performance and adding start training to regular training sessions. Moreover, youth male and female swimmers can participate together in the grab start training

Is Increased Residual Shank Length a Competitive Advantage for Elite Transtibial Amputee Long Jumpers?

2011 ◽  
Vol 28 (3) ◽  
pp. 267-276 ◽  
Author(s):  
Lee Nolan ◽  
Benjamin L. Patritti ◽  
Laura Stana ◽  
Sean M. Tweedy
Keyword(s):  
Vertical Velocity ◽  
Important Determinant ◽  
Elite Athletes ◽  
Center Of Mass ◽  
Transtibial Amputation ◽  
Jump Performance ◽  
Performance Variables ◽  
Jump Distance ◽  
Long Jump ◽  
The Relationship

The purpose of this study was to evaluate the extent to which residual shank length affects long jump performance of elite athletes with a unilateral transtibial amputation. Sixteen elite, male, long jumpers with a transtibial amputation were videoed while competing in major championships (World Championships 1998, 2002 and Paralympic Games, 2004). The approach, take-off, and landing of each athlete’s best jump was digitized to determine residual and intact shank lengths, jump distance, and horizontal and vertical velocity of center of mass at touchdown. Residual shank length ranged from 15 cm to 38 cm. There were weak, nonsignificant relationships between residual shank length and (a) distance jumped (r = 0.30), (b) horizontal velocity (r = 0.31), and vertical velocity (r = 0.05). Based on these results, residual shank length is not an important determinant of long jump performance, and it is therefore appropriate that all long jumpers with transtibial amputation compete in the same class. The relationship between residual shank length and key performance variables was stronger among athletes that jumped off their prosthetic leg (N = 5), and although this result must be interpreted cautiously, it indicates the need for further research.

scholarly journals Flux Attenuation due to Sensor Displacement over Sea

2010 ◽  
Vol 27 (5) ◽  
pp. 856-868 ◽  
Author(s):  
Erik O. Nilsson ◽  
Anna Rutgersson ◽  
Peter P. Sullivan
Keyword(s):  
Vertical Velocity ◽  
Atmospheric Stability ◽  
Correlation Method ◽  
Spatial Separation ◽  
Horizontal Displacement ◽  
Vertical Displacement ◽  
Eddy Correlation ◽  
Correction Function ◽  
Obukhov Length ◽  
Flux Loss

Abstract When using the eddy correlation method to measure turbulent scalar fluxes, there is often a spatial separation between the instruments measuring the scalar and the vertical velocity. The attenuation of the flux due to this separation is studied here for marine conditions. Measurements of a two-point covariance between vertical velocity and temperature are compared to covariance measurements from collocated sensors for both horizontal and vertical displacements, with the purpose of finding the approximate functions to describe the flux loss for typical separation distances. On the basis of this study’s measurements, there is only a slight directional dependence (i.e., streamwise or crosswind separation) of the flux loss for sensor separation distances less than 1 m but an increasing dependence with increasing displacement distance. For a vertical displacement, observations from this study confirm that flux loss is less with the scalar sensor positioned below the velocity sensor than at an equal distance above. Furthermore, the data show a clear dependence on atmospheric stability with increasing flux loss for increasing stable stratification, but it is not as large as that found in previous studies of flux attenuation over land. For example, the authors compare estimated flux loss for neutral and moderately stable (z/L = 0.3) stratification at a measuring height of z = 10 m and a sensor displacement r = 0.3 m, where L is the Obukhov length. For neutral (stable, z/L = 0.3) stratification the estimated loss of flux is 3% (5%) of the total flux for horizontal displacement. Whereas for an equal vertical separation the estimates are 2% (4%) when the scalar sensor is placed above the anemometer but less than 1% (2%) if it is placed below. Thus, the authors conclude that placing the scalar sensor below the anemometer minimizes the flux loss due to sensor separation, and that a simple correction function can be used to quantify the mean flux loss due to sensor separation over sea.

The Roche Vault Performed by Elite Gymnasts: Somersaulting Technique, Deterministic Model, and Judges’ Scores

2007 ◽  
Vol 23 (1) ◽  
pp. 1-11 ◽  
Author(s):  
Yoshiaki Takei
Keyword(s):  
Deterministic Model ◽  
Center Of Mass ◽  
Horizontal Displacement ◽  
Horizontal Distance ◽  
Transformation Technique ◽  
Landing Point ◽  
Body Center ◽  
Spatial Calibration ◽  
The Relationship ◽  
Single Predictor

The purpose of the study was to determine the mechanical variables that are related to successful post-flight somersaulting performance of the Roche vault. The 23 Roche vaults performed during the 2000 Olympic Games were filmed by a 16-mm camera operating at 100 Hz. The 2-D direct linear transformation technique was used for spatial calibration. Approximately 60 frames were digitized per vault. The method of Hay and Reid (1988) was used to develop a deterministic model to identify the mechanical variables that govern linear and angular motions of the vault. Correlational analysis was used to establish the strength of the relationship between the mechanical variables identified and the judges’ scores. Significant correlations indicated that the higher judges’ scores were negatively related to five mechanical variables and positively related to seventeen variables in the model. The normalized horizontal displacement of body center of mass (CM) from the knee grasp to the peak of post-flight was the best single predictor of the judges’ score and accounted for 50% of variation in the judges’ score. Finally, the landing point deductions and the official horizontal distance of post-flight collectively accounted for 86% of the variance in the judges’ scores.

scholarly journals The relationship between physical fitness attributes and sports injury in female, team ball sport players: a systematic review

2020 ◽  
Vol 6 (1) ◽  
Author(s):  
Jessica B. Farley ◽  
Lily M. Barrett ◽  
Justin W. L. Keogh ◽  
Carl T. Woods ◽  
Nikki Milne
Keyword(s):  
Systematic Review ◽  
Body Composition ◽  
Physical Fitness ◽  
Sports Injury ◽  
Quality Data ◽  
Body Region ◽  
Ankle Sprains ◽  
Level Of Evidence ◽  
Data Synthesis ◽  
The Relationship

Abstract Background Understanding the relationships between physical fitness characteristics and sports injury may assist with the development of injury minimisation programs. The purpose of this systematic review was to investigate the association between physical fitness attributes and sports injury in female, team ball sport players. Methods Four scientific databases (MEDLINE, EMBASE, SPORTDiscus, Scopus) and reference lists of relevant research were searched for eligible studies up to September 2, 2019. Full-text articles examining the relationship between physical fitness and sports injury in female, team ball sport players were included. A modified Downs and Black checklist was used to assess methodological quality. Data synthesis determined summary conclusions based on the number of significant relationships divided by the total relationships investigated and reported as a percentage. Level of certainty was identified for summary conclusions based on level of evidence. Sub-analyses regarding competition level, age, and single injury types were also conducted. Results A total of 44 studies were included. Data synthesis revealed no associations (low to moderate certainty) between body composition (1/9; 11%), flexibility (18–20%), and balance (2/8; 25%) and ‘any injury’ classification. No associations (mostly of moderate certainty) were found between flexibility (0–27%), muscular strength (0–27%), and body composition (14–33%) and various body region injury classifications, whereas mixed summary conclusions were shown for balance (0-48%). Many associations between physical fitness and sports injury were deemed ‘unknown’ or with an insufficient level of certainty. Sub-analyses revealed no association between strength and noncontact ACL injuries (0/5; 0%) or ankle sprains (0/12; 0%), and between flexibility and ankle sprains (1/5; 20%); however, insufficient certainty of these results exists. Clear associations were concluded between balance and lower body injuries in female, non-elite (10/16; 63%) and junior (9/12; 75%) team ball sport players, with moderate and insufficient certainty of these results, respectively. Conclusion Limited evidence is available to demonstrate relationships between physical fitness and sports injury in female, team ball sport players. High-quality evidence investigating the multifactorial nature of sports injury, including the interactions physical fitness qualities have with other injury determinants, is needed to better understand the role of physical fitness in minimising sports injuries in female, team ball sport players. Trial Registration CRD42017077374 (PROSPERO on September 14, 2017).

scholarly journals The product of trunk muscle area and density on the CT image is a good indicator of energy expenditure in patients with or at risk for COPD

2021 ◽  
Vol 22 (1) ◽  
Author(s):  
Toru Shirahata ◽  
Hideaki Sato ◽  
Sanehiro Yogi ◽  
Kaiji Inoue ◽  
Mamoru Niitsu ◽  
...  
Keyword(s):  
At Risk ◽  
Body Composition ◽  
Energy Expenditure ◽  
Trunk Muscle ◽  
Rectus Abdominis ◽  
Activity Level ◽  
Erector Spinae ◽  
Trunk Muscles ◽  
Muscle Area ◽  
The Relationship

Abstract Background Physical inactivity due to cachexia and muscle wasting is well recognized as a sign of poor prognosis in chronic obstructive pulmonary disease (COPD). However, there have been no reports on the relationship between trunk muscle measurements and energy expenditure parameters, such as the total energy expenditure (TEE) and physical activity level (PAL), in COPD. In this study, we investigated the associations of computed tomography (CT)-derived muscle area and density measurements with clinical parameters, including TEE and PAL, in patients with or at risk for COPD, and examined whether these muscle measurements serve as an indicator of TEE and PAL. Methods The study population consisted of 36 male patients with (n = 28, stage 1–4) and at risk for (n = 8) COPD aged over 50 years. TEE was measured by the doubly labeled water method, and PAL was calculated as the TEE/basal metabolic rate estimated by the indirect method. The cross-sectional areas and densities of the pectoralis muscles, rectus abdominis muscles, and erector spinae muscles were measured. We evaluated the relationship between these muscle measurements and clinical outcomes, including body composition, lung function, muscle strength, TEE, and PAL. Results All the muscle areas were significantly associated with TEE, severity of emphysema, and body composition indices such as body mass index, fat-free mass, and trunk muscle mass. All trunk muscle densities were correlated with PAL. The product of the rectus abdominis muscle area and density showed the highest association with TEE (r = 0.732) and PAL (r = 0.578). Several trunk muscle measurements showed significant correlations with maximal inspiratory and expiratory pressures, indicating their roles in respiration. Conclusions CT-derived measurements for trunk muscles are helpful in evaluating physical status and function in patients with or at risk for COPD. Particularly, trunk muscle evaluation may be a useful marker reflecting TEE and PAL.

scholarly journals SINGLE LEG SQUAT COMPENSATIONS ASSOCIATE WITH SOFTBALL PITCHING PATHOMECHANICS IN ADOLESCENT SOFTBALL PITCHERS

2021 ◽  
Vol 9 (7_suppl3) ◽  
pp. 2325967121S0006
Author(s):  
Gretchen D. Oliver ◽  
Kenzie B. Friesen ◽  
Regan E. Shaw ◽  
David Shannon ◽  
Jeffrey Dugas ◽  
...  
Keyword(s):  
Center Of Mass ◽  
Knee Valgus ◽  
Trunk Rotation ◽  
Lateral Flexion ◽  
Trunk Flexion ◽  
Backward Elimination ◽  
Potential Risk Factors ◽  
Single Leg Squat ◽  
Tracking Device ◽  
The Relationship

Background: Softball pitchers have an eminent propensity for injury due to the high repetition and ballistic nature of the pitch. As such, trunk pathomechanics during pitching have been associated with upper extremity pain. The single leg squat (SLS) is a simple diagnostic tool used to examine LPHC and trunk stability. Research shows a lack of LPHC stability is often associated with altered pitching mechanics consequently increasing pain and injury susceptibility. Hypothesis/Purpose: The purpose of this study was to examine the relationship between trunk compensatory kinematics during the SLS and kinematics during foot contact of the windmill pitch. The authors hypothesized there would be a relationship between SLS compensations and pitch kinematics previously associated with injury. In using a simple clinical assessment such as the SLS, athletes, coaches, parents, and clinicians can identify potential risk factors that may predispose the athlete to injurious movement patterns. Methods: Fifty-five youth and high school softball pitchers (12.6±2.2 years, 160.0±11.0 cm, 60.8±15.5 kg) were recruited to participate. Kinematic data were collected at 100Hz using an electromagnetic tracking device. Participants were asked to complete a SLS on their stride leg (contralateral to their throwing arm), then throw 3 fastballs at maximal effort. Values of trunk flexion, trunk lateral flexion, and trunk rotation at peak depth of the SLS were used as the dependent variables in three separate backward elimination regression analyses. Independent variables examined at foot contact of the pitch included: trunk flexion, trunk lateral flexion, trunk rotation, center of mass, stride length, and stride knee valgus. Results: The SLS trunk rotation regression, F(1,56) = 4.980, p = .030, revealed trunk flexion significantly predicted SLS trunk rotation (SE = .068, t = 2.232, p = .030) and explained approximately 7% of variance (Adj. R2 = .066). The SLS trunk flexion regression, F(1,56) = 5.755, p = .020, revealed stride knee valgus significantly predicted SLS trunk flexion (SE = .256, t = 2.399, p = .020) and explained approximately 8% of variance (Adj. R2 = .078). Conclusion/Significance: Additional trunk rotation and trunk flexion at peak depth of the SLS indicate increased knee valgus and trunk flexion at foot contact of the pitch, both of which suggest poor LPHC stability, may increase the potential for injury. Athletes, coaches and clinicians should acknowledge the risk of poor LPHC in softball pitching and implement exercises to improve LPHC stability in effort to decrease pitching pathomechanics and associated pain.

scholarly journals Acute Effects of Handheld Loading on Standing Broad Jump in Youth Athletes

2021 ◽  
Vol 18 (9) ◽  
pp. 5046
Author(s):  
Wei-Hsun Tai ◽  
Ray-Hsien Tang ◽  
Chen-Fu Huang ◽  
Shin-Liang Lo ◽  
Yu-Chi Sung ◽  
...  
Keyword(s):  
High Speed ◽  
Center Of Mass ◽  
Reaction Force ◽  
Sampling Rate ◽  
Random Order ◽  
Horizontal Distance ◽  
Acute Effects ◽  
Vertical Ground Reaction Force ◽  
Strength And Conditioning ◽  
Peak Knee

The study aimed to investigate the acute effects of handheld loading on standing broad jump (SBJ) performance and biomechanics. Fifteen youth male athletes (mean age: 14.7 ± 0.9 years; body mass: 59.3 ± 8.0 kg; height: 1.73 ± 0.07 m) volunteered to participate in the study. Participants were assigned to perform SBJ with and without 4 kg dumbbells in a random order. Kinematic and kinetic data were collected using 10 infrared high-speed motion-capture cameras at a 250 Hz sampling rate and two force platforms at a 1000 Hz sampling rate. A paired t-test was applied to all variables to determine the significance between loading and unloading SBJs. Horizontal distance (p < 0.001), take-off distance (p = 0.001), landing distance (p < 0.001), horizontal velocity of center of mass (CoM; p < 0.001), push time (p < 0.001), vertical impulse (p = 0.003), and peak horizontal and vertical ground reaction force (GRF; p < 0.001, p = 0.017) were significantly greater in loading SBJ than in unloading SBJ. The take-off vertical velocity of CoM (p = 0.001), take-off angle (p < 0.001), peak knee and hip velocity (p < 0.001, p = 0.007), peak ankle and hip moment (p = 0.006, p = 0.011), and peak hip power (p = 0.014) were significantly greater in unloading SBJ than in loading SBJ. Conclusions: Acute enhancement in SBJ performance was observed with handheld loading. The present findings contribute to the understanding of biomechanical differences in SBJ performance with handheld loading and are highly applicable to strength and conditioning training for athletes.

scholarly journals Distance Motor Learning during the COVID-19 Induced Confinement: Video Feedback with a Pedagogical Activity Improves the Snatch Technique in Young Athletes

2021 ◽  
Vol 18 (6) ◽  
pp. 3069
Author(s):  
Mohamed Abdelkader Souissi ◽  
Achraf Ammar ◽  
Omar Trabelsi ◽  
Jordan M. Glenn ◽  
Omar Boukhris ◽  
...  
Keyword(s):  
Retention Test ◽  
Horizontal Displacement ◽  
Test Session ◽  
Video Feedback ◽  
Control Group ◽  
Maximum Height ◽  
Kinematic Parameters ◽  
School Aged Children ◽  
Cohen’S D ◽  
Cohen's D

The purpose of the present study was to investigate which of two strategies, Video Feedback with Pedagogical Activity (VF-PA) or Video Feedback (VF), would be more beneficial for the remote error correction of the snatch weightlifting technique during the confinement period. Thirty-five school aged children with at least three months of weightlifting experience were randomized to one of three training conditions: VF-PA, VF or the Control group (CONT). Subjects underwent test sessions one week before (T0) and one day after (T1) a six-session training period and a retention test session a week later (T2). During each test session, the Kinovea version 0.8.15 software measured the kinematic parameters of the snatch performance. Following distance learning sessions (T1), the VF-PA improved various kinematic parameters (i.e., barbell horizontal displacements, maximum height, looping and symmetry) compared with T0 (p < 0.5; Cohen’s d = 0.58–1.1). Most of these improvements were maintained during the retention test (T2) (p<0.01, Cohen’s d = 1.2–1.3) when compared withT0. However, the VF group improved only twoparameters (i.e., barbell symmetry and horizontal displacement) at T1 (p < 0.05; Cohen’s d = 0.9), which were not maintained at T2. Better horizontal displacement and looping values were registered during the retention test in the VF-PA group compared with theCONT group (p < 0.05, Cohen’s d = 1.49–1.52). The present findings suggest combining video feedback with pedagogical activity during the pandemic induced online coaching or physical education to improve movement learning in school aged children.

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