Comparison of Endpoint Data Treatment Methods for the Estimation of Kinematics and Kinetics Near Impact During the Tennis Serve

2012 ◽  
Vol 28 (1) ◽  
pp. 93-98 ◽  
Author(s):  
M. M. Reid ◽  
Amity C. Campbell ◽  
B. C. Elliott

Tennis stroke mechanics have attracted considerable biomechanical analysis, yet current filtering practice may lead to erroneous reporting of data near the impact of racket and ball. This research had three aims: (1) to identify the best method of estimating the displacement and velocity of the racket at impact during the tennis serve, (2) to demonstrate the effect of different methods on upper limb kinematics and kinetics and (3) to report the effect of increased noise on the most appropriate treatment method. The tennis serves of one tennis player, fit with upper limb and racket retro-reflective markers, were captured with a Vicon motion analysis system recording at 500 Hz. The raw racket tip marker displacement and velocity were used as criterion data to compare three different endpoint treatments and two different filters. The 2nd-order polynomial proved to be the least erroneous extrapolation technique and the quintic spline filter was the most appropriate filter. The previously performed “smoothing through impact” method, using a quintic spline filter, underestimated the racket velocity (9.1%) at the time of impact. The polynomial extrapolation method remained effective when noise was added to the marker trajectories.

2009 ◽  
Vol 2009.5 (0) ◽  
pp. 185-186
Author(s):  
Hideharu KODA ◽  
Koichi SAGAWA ◽  
Kouta KUROSHIMA ◽  
Toshiaki TSUKAMOTO ◽  
Kazutaka URITA ◽  
...  

PeerJ ◽  
2018 ◽  
Vol 6 ◽  
pp. e4760 ◽  
Author(s):  
Changxiao Yu ◽  
Shirui Shao ◽  
Julien S. Baker ◽  
Yaodong Gu

Background The table tennis serve involves complex spatial movements combined with biomechanial characteristics. Although the differences in lower-limb biomechanial characteristics to a great extent influence the translational and spinning velocity of the ball when using the different styles of table tennis serve, few researchers have studied their mechanics. Therefore, the aim of this study was to investigate the differences in lower-limb activity between the squat and standing serves during a table tennis short serve. Methods Ten advanced female table tennis participants performed a squat serve and standing serve in random order. A Vicon motion analysis system and a Novel Pedar insole plantar pressure measurement system were used to record kinematics and kinetics data, respectively. Results Key findings from the study were that the squat serve not only showed significantly larger hip and knee flexion, as well as ankle dorsiflexion, it also showed significantly larger hip adduction and external knee rotation, with larger changing angular rate of the lower limb joints in the sagittal and the transverse planes when the two serving styles were compared. In addition, the force-time integral (FTI) was higher in the rear foot area for the standing serve. Discussion The results demonstrated that the squat serve needs higher lower limb drive during a table tennis short serve compared with a standing serve. These biomechanical considerations may be beneficial for table tennis athletes and coaches as a method of optimizing performance characteristics during both competition and training.


Author(s):  
Kuang Li ◽  
Si Qin Shen ◽  
Ee Chon Teo ◽  
Min Jun Liang

Many scientific data have proven that regular wearing of high-heeled shoes adversely affects human health. Recent evidence suggested that bionic heels imitated hoofed animals have attracted widespread attention. However, few biomechanical studies have investigated the effects of bionic high-heeled footwear on the lower limbs. Accordingly, this study aimed to examine the impact of bionic high-heeled shoes (HHS) on the biomechanical characteristics of lower limbs by comparing kinematics and kinetics of walking in HHS and bionic flat-bottomed shoes (FBS). they find that when the subjects wore HHS, the loading is concentrated in the forefoot region for a much longer time. Couple with HHS lacks the cushioning effect of the complete sole, the sole has to rely only on plantar flexion and dorsiflexion of the ankle joint to cushion the impact force, which will undoubtedly increase the fatigue damage of the ankle joint. The unique split-toe structure balances the loading between the toes could reduce the risk of toes injury during walking. However, there are still risks of injury to the lower limbs of HHS, especially the ankle and knee joints.


Foods ◽  
2021 ◽  
Vol 10 (7) ◽  
pp. 1610
Author(s):  
Wiesław Przybylski ◽  
Danuta Jaworska ◽  
Katarzyna Kajak-Siemaszko ◽  
Piotr Sałek ◽  
Kacper Pakuła

An increase in the consumption of poultry meat has been observed due to its availability, nutritional value, and delicate flavor. These characteristics make it possible to prepare, with the use of spices and other additives, many different dishes and products for increasingly demanding consumers. The sous-vide technique is increasingly being used to give new sensory attributes to dishes in gastronomy. The study aimed to assess the impact of the heat treatment method, i.e., the sous-vide method, as compared to traditional cooking, on the sensory quality of poultry meat, as well as the efficiency of the process with regard to technological quality. The cooking yield with the sous-vide method of processing poultry meat was higher than with the traditional method of cooking in water (88.5% vs. 71.0%, respectively). The meat was also found to be redder (a* = 254 vs. 074) and less yellow (b* = 1512 vs. 1649), as well as more tender. The sensory quality of chicken breast meat obtained by the sous-vide method was higher in terms of attributes such as color tone, tenderness, juiciness, and overall quality. At the same time, it was lower in terms of the odor of cooked meat and the flavor of cooked meat as compared to meat subjected to traditional cooking.


2020 ◽  
pp. 1-7
Author(s):  
Tara Sims

BACKGROUND: The impact of paediatric upper limb difference may extend beyond the child themselves to their parents and other family members. Previous research has found that feelings of shock, numbness and loss are common amongst parents and that peer support can be a buffer against stress. OBJECTIVE: The current study aimed to explore the experiences of parents of children with limb difference, and the role of services and prosthetic devices in these experiences. METHODS: Nine parents of children with limb difference participated in either a group (n= 2) or individual (n= 7) interview. RESULTS: Analysis of the interview transcripts revealed four themes – ‘grief and guilt’, ‘prosthesis as a tool for parental adjustment’, ‘support’ and ‘fun and humour’. CONCLUSIONS: Parents may employ coping strategies to help them adjust to their child’s limb difference, including use of a prosthesis, accessing support from statutory services and peers, and use of fun and humour within the family.


Author(s):  
Hadar Lackritz ◽  
Yisrael Parmet ◽  
Silvi Frenkel-Toledo ◽  
Melanie C. Baniña ◽  
Nachum Soroker ◽  
...  

Abstract Background Hemiparesis following stroke is often accompanied by spasticity. Spasticity is one factor among the multiple components of the upper motor neuron syndrome that contributes to movement impairment. However, the specific contribution of spasticity is difficult to isolate and quantify. We propose a new method of quantification and evaluation of the impact of spasticity on the quality of movement following stroke. Methods Spasticity was assessed using the Tonic Stretch Reflex Threshold (TSRT). TSRT was analyzed in relation to stochastic models of motion to quantify the deviation of the hemiparetic upper limb motion from the normal motion patterns during a reaching task. Specifically, we assessed the impact of spasticity in the elbow flexors on reaching motion patterns using two distinct measures of the ‘distance’ between pathological and normal movement, (a) the bidirectional Kullback–Liebler divergence (BKLD) and (b) Hellinger’s distance (HD). These measures differ in their sensitivity to different confounding variables. Motor impairment was assessed clinically by the Fugl-Meyer assessment scale for the upper extremity (FMA-UE). Forty-two first-event stroke patients in the subacute phase and 13 healthy controls of similar age participated in the study. Elbow motion was analyzed in the context of repeated reach-to-grasp movements towards four differently located targets. Log-BKLD and HD along with movement time, final elbow extension angle, mean elbow velocity, peak elbow velocity, and the number of velocity peaks of the elbow motion were computed. Results Upper limb kinematics in patients with lower FMA-UE scores (greater impairment) showed greater deviation from normality when the distance between impaired and normal elbow motion was analyzed either with the BKLD or HD measures. The severity of spasticity, reflected by the TSRT, was related to the distance between impaired and normal elbow motion analyzed with either distance measure. Mean elbow velocity differed between targets, however HD was not sensitive to target location. This may point at effects of spasticity on motion quality that go beyond effects on velocity. Conclusions The two methods for analyzing pathological movement post-stroke provide new options for studying the relationship between spasticity and movement quality under different spatiotemporal constraints.


2011 ◽  
Vol 27 (2) ◽  
pp. 108-115 ◽  
Author(s):  
Joshua T. Weinhandl ◽  
Jeremy D. Smith ◽  
Eric L. Dugan

The purpose of the study was to investigate the effects of fatigue on lower extremity joint kinematics, and kinetics during repetitive drop jumps. Twelve recreationally active males (n= 6) and females (n= 6) (nine used for analysis) performed repetitive drop jumps until they could no longer reach 80% of their initial drop jump height. Kinematic and kinetic variables were assessed during the impact phase (100 ms) of all jumps. Fatigued landings were performed with increased knee extension, and ankle plantar flexion at initial contact, as well as increased ankle range of motion during the impact phase. Fatigue also resulted in increased peak ankle power absorption and increased energy absorption at the ankle. This was accompanied by an approximately equal reduction in energy absorption at the knee. While the knee extensors were the muscle group primarily responsible for absorbing the impact, individuals compensated for increased knee extension when fatigued by an increased use of the ankle plantar flexors to help absorb the forces during impact. Thus, as fatigue set in and individuals landed with more extended lower extremities, they adopted a landing strategy that shifted a greater burden to the ankle for absorbing the kinetic energy of the impact.


PLoS ONE ◽  
2015 ◽  
Vol 10 (8) ◽  
pp. e0133709 ◽  
Author(s):  
Jessica Despard ◽  
Anne-Marie Ternes ◽  
Bleydy Dimech-Betancourt ◽  
Govinda Poudel ◽  
Andrew Churchyard ◽  
...  

2021 ◽  
Vol 13 (1) ◽  
pp. 46-58
Author(s):  
João Paulo Branco ◽  
Filipa Rocha ◽  
João Sargento-Freitas ◽  
Gustavo C. Santo ◽  
António Freire ◽  
...  

The objective of this study is to assess the impact of recanalization (spontaneous and therapeutic) on upper limb functioning and general patient functioning after stroke. This is a prospective, observational study of patients hospitalized due to acute ischemic stroke in the territory of the middle cerebral artery (n = 98). Patients completed a comprehensive rehabilitation program and were followed-up for 24 weeks. The impact of recanalization on patient functioning was evaluated using the modified Rankin Scale (mRS) and Stroke Upper Limb Capacity Scale (SULCS). General and upper limb functioning improved markedly in the first three weeks after stroke. Age, gender, and National Institutes of Health Stroke Scale (NIHSS) score at admission were associated with general and upper limb functioning at 12 weeks. Successful recanalization was associated with better functioning. Among patients who underwent therapeutic recanalization, NIHSS scores ≥16.5 indicate lower general functioning at 12 weeks (sensibility = 72.4%; specificity = 78.6%) and NIHSS scores ≥13.5 indicate no hand functioning at 12 weeks (sensibility = 83.8%; specificity = 76.5%). Recanalization, either spontaneous or therapeutic, has a positive impact on patient functioning after acute ischemic stroke. Functional recovery occurs mostly within the first 12 weeks after stroke, with greater functional gains among patients with successful recanalization. Higher NIHSS scores at admission are associated with worse functional recovery.


Author(s):  
Aaron Michael Pangan ◽  
Matthew J Leineweber

Abstract The back squat is one of the most effective exercises in strengthening the muscles of the lower extremity. Understanding the impact of footwear has on the biomechanics is imperative for maximizing the exercise training potential, preventing injury, and rehabilitating from injury. This review focuses on how different types of footwear affect the full-body kinematics, joint loads, muscle activity, and ground reaction forces in athletes of varying experience performing the weighted back squat. The literature search was conducted using three databases, and fourteen full-text articles were ultimately included in the review. The majority of these studies demonstrated that the choice of footwear directly impacts kinematics and kinetics. Weightlifting shoes were shown to decrease trunk lean and generate more plantarflexion relative to running shoes and barefoot lifting. Elevating the heel through the use of external squat wedges is popular clinical exercise during rehabilitation and was shown to provide similar effects to WLS. Additional research with a broader array of populations, particularly novice and female weightlifters, should be conducted to generalize the research results to non-athlete populations. Further work is also needed to characterize the specific effects of sole stiffness and heel elevation height on squatting mechanics.


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