Trunk muscle activation during golf swing: Baseline and threshold

There is a lack of studies regarding EMG temporal analysis during dynamic and complex motor tasks, such as golf swing. The aim of this study is to analyze the EMG onset during the golf swing, by comparing two different threshold methods. Method A threshold was determined using the baseline activity recorded between two maximum voluntary contraction (MVC). Method B threshold was calculated using the mean EMG activity for 1000 ms before the 500 ms prior to the start of the Backswing. Two different clubs were also studied. Three-way repeated measures ANOVA was used to compare methods, muscles and clubs. Two-way mixed Intraclass Correlation Coefficient (ICC) with absolute agreement was used to determine the methods reliability.Club type usage showed no influence in onset detection. Rectus abdominis (RA) showed the higher agreement between methods. Erector spinae (ES), on the other hand, showed a very low agreement, that might be related to postural activity before the swing. External oblique (EO) is the first being activated, at 1295 ms prior impact. There is a similar activation time between right and left muscles sides, although the right EO showed better agreement between methods than left side. Therefore, the algorithms usage is task- and muscle-dependent.     

Latent effect of passive static stretching on driver clubhead speed, distance, accuracy, and consistent ball contact in young male competitive golfers

This investigation was conducted to determine the effect of 2 different warm-up treatments over time on driver clubhead speed, distance, accuracy, and consistent ball contact in young male competitive golfers. Two supervised warm-up treatments, an active dynamic warm-up with golf clubs (AD) and a 20-minute total body passive static stretching routine plus an identical AD warm-up (PSS), were applied before each performance testing session using a counterbalanced design on nonconsecutive days. Immediately after the AD treatment, subjects were instructed to hit 3 full swing golf shots with their driver with 1-minute rest between trials. Immediately after the PSS treatment, subjects were instructed to hit 3 full-swing golf shots with their driver at t0 and thereafter at t15, t30, t45, and t60 minutes with 1-minute rest between swing trials to determine any latent effects of PSS on golf driver performance measures. Results of paired t-tests revealed significant (p < 0.05) decreases in clubhead speed at t0 (-4.92%), t15 (-2.59%), and t30 (-2.19%) but not at t45 (-0.95) or t60 (-0.99). Significant differences were also observed in distance at t0 (-7.26%), t15 (-5.19%), t30 (-5.47%), t45 (-3.30%), and t60 (-3.53%). Accuracy was significantly impaired at t0 (61.99%), t15 (58.78%), t30 (59.46%), and t45 (61.32%) but not at t60 (36.82%). Finally, consistent ball contact was significantly reduced at t0 (-31.29%), t15 (-31.29%), t30 (-23.56%), t45 (-27.49%), and t60 (-15.70%). Plausible explanations for observed performance decrements include a more compliant muscle-tendon unit (MTU) and an altered neurological state because of the PSS treatment. Further, the findings of this study provide evidence supporting the theory that the mechanical properties of the MTU may recover at a faster rate than any associated neurological changes. The results of this inquiry strongly suggest that a total-body passive static stretching routine should be avoided before practice or competition in favor of a gradual AD. Athletes with poor mechanics because of lack of flexibility should perform these exercises after a conditioning session, practice, or competition.     

An eight-week golf-specific exercise program improves physical characteristics, swing mechanics, and golf performance in recreational golfers

The purpose of this study was to determine the effects of an 8-week golf-specific exercise program on physical characteristics, swing mechanics, and golf performance. Fifteen trained male golfers (47.2 +/- 11.4 years, 178.8 +/- 5.8 cm, 86.7 +/- 9.0 kg, and 12.1 +/- 6.4 U.S. Golf Association handicap) were recruited. Trained golfers was defined operationally as golfers who play a round of golf at least 2-3 times per week and practice at the driving range at least 2-3 times per week during the regular golf season. Subjects performed a golf-specific conditioning program 3-4 times per week for 8 weeks during the off-season in order to enhance physical characteristics. Pre- and posttraining testing of participants included assessments of strength (torso, shoulder, and hip), flexibility, balance, swing mechanics, and golf performance. Following training, torso rotational strength and hip abduction strength were improved significantly (p < 0.05). Torso, shoulder, and hip flexibility improved significantly in all flexibility measurements taken (p < 0.05). Balance was improved significantly in 3 of 12 measurements, with the remainder of the variables demonstrating a nonsignificant trend for improvement. The magnitude of upper-torso axial rotation was decreased at the acceleration (p = 0.015) and impact points (p =0.043), and the magnitude of pelvis axial rotation was decreased at the top (p = 0.031) and acceleration points (p = 0.036). Upper-torso axial rotational velocity was increased significantly at the acceleration point of the golf swing (p = 0.009). Subjects increased average club velocity (p = 0.001), ball velocity (p = 0.001), carry distance (p = 0.001), and total distance (p = 0.001). These results indicate that a golf-specific exercise program improves strength, flexibility, and balance in golfers. These improvements result in increased upper-torso axial rotational velocity, which results in increased club head velocity, ball velocity, and driving distance.     

Coordination of lower extremity multi-joint control strategies during the golf swing

This study aimed to understand how players coordinate the multi-joint control strategies of the rear and target legs to satisfy the lower extremity and whole-body mechanical objectives during the golf swing when hitting shots with different clubs. Highly skilled golf players (n = 10) performed golf swings with a 6-iron and a driver. Joint kinetics were calculated using ground reaction forces and segment kinematics to determine net joint moments (NJMs) during the interval of interest within the downswing. Between club difference in NJMs and 3D support moments were compared across the group and within a player. Although player-specific multi-joint control strategies arose, players generally increased target leg ankle, knee, and hip NJMs when hitting with the driver while maintaining the relative contribution to the 3D support moment. Multi-joint control strategies used to control the target and rear legs were found to be different, yet the majority of the 3D support moment was produced by NJMs about an axis perpendicular to the leg planes. These results emphasize the importance of recognizing how an individual player coordinates multi-joint control from each leg, and highlights the need to design interventions that are player and leg specific to aid in improving player performance.     

Life history and spatial distribution of Oriental beetle (Coleoptera: Scarabaeidae) in golf courses in Korea

Larval and adult activity of the oriental beetle Exomala orientalis (Waterhouse), a pest of turfgrass in Korea, was investigated at four golf clubs in Pusan, Korea, from 1995 to 1999. Adult emergence was first observed on the greens in late May with peak activity occurring 2 wk later. During the day, E. orientalis adults were most active between 1800 and 2200 hours. First instars were found mostly in early July, second instars mostly in late July, and third instars from August to April. The density of larvae in fixed plots decreased steadily from the time of egg laying to pupation: 667/m3 on 26 July, 267/m3 on 29 August, and 122/m3 on 2 October 1997. All the observed E. orientalis completed one generation per year. Adult females were observed feeding on flowers of a late-blooming variety of Japanese chestnut (Castanea crenata Sieb & Zucc). E. orientalis larval densities were higher in greens with Japanese chestnut nearby, and where magpie, Pica pica sericea (Gould), feeding was observed. More E. orientalis adults emerged from the right, left, and back of greens than from the front or middle. The intensity of emergence was inversely proportional to the amount of golfer traffic on various parts of the green. Counting emergence holes may be a way that golf course superintendents can predict which greens and tees are most likely to be damaged from E. orientalis larvae without destructive sampling.     

Putting like a pro: the role of positive contagion in golf performance and perception

Many amateur athletes believe that using a professional athlete's equipment can improve their performance. Such equipment can be said to be affected with positive contagion, which refers to the belief of transference of beneficial properties between animate persons/objects to previously neutral objects. In this experiment, positive contagion was induced by telling participants in one group that a putter previously belonged to a professional golfer. The effect of positive contagion was examined for perception and performance in a golf putting task. Individuals who believed they were using the professional golfer's putter perceived the size of the golf hole to be larger than golfers without such a belief and also had better performance, sinking more putts. These results provide empirical support for anecdotes, which allege that using objects with positive contagion can improve performance, and further suggest perception can be modulated by positive contagion.     

Effect of shoulder model complexity in upper-body kinematics analysis of the golf swing

The golf swing is a complex full body movement during which the spine and shoulders are highly involved. In order to determine shoulder kinematics during this movement, multibody kinematics optimization (MKO) can be recommended to limit the effect of the soft tissue artifact and to avoid joint dislocations or bone penetration in reconstructed kinematics. Classically, in golf biomechanics research, the shoulder is represented by a 3 degrees-of-freedom model representing the glenohumeral joint. More complex and physiological models are already provided in the scientific literature. Particularly, the model used in this study was a full body model and also described motions of clavicles and scapulae. This study aimed at quantifying the effect of utilizing a more complex and physiological shoulder model when studying the golf swing. Results obtained on 20 golfers showed that a more complex and physiologically-accurate model can more efficiently track experimental markers, which resulted in differences in joint kinematics. Hence, the model with 3 degrees-of-freedom between the humerus and the thorax may be inadequate when combined with MKO and a more physiological model would be beneficial. Finally, results would also be improved through a subject-specific approach for the determination of the segment lengths.     

Electromyography variables during the golf swing: A literature review

The aim of the study was to review systematically the literature available on electromyographic (EMG) variables of the golf swing. From the 19 studies found, a high variety of EMG methodologies were reported. With respect to EMG intensity, the right erector spinae seems to be highly activated, especially during the acceleration phase, whereas the oblique abdominal muscles showed moderate to low levels of activation. The pectoralis major, subscapularis and latissimus dorsi muscles of both sides showed their peak activity during the acceleration phase. High muscle activity was found in the forearm muscles, especially in the wrist flexor muscles demonstrating activity levels above the maximal voluntary contraction. In the lower limb higher muscle activity of the trail side was found. There is no consensus on the influence of the golf club used on the neuromuscular patterns described. Furthermore, there is a lack of studies on average golf players, since most studies were executed on professional or low handicap golfers.Further EMG studies are needed, especially on lower limb muscles, to describe golf swing muscle activation patterns and to evaluate timing parameters to characterize neuromuscular patterns responsible for an efficient movement with lowest risk for injury.     

Prediction of the structural response of the femoral shaft under dynamic loading using subject-specific finite element models

The goal of this study was to predict the structural response of the femoral shaft under dynamic loading conditions using subject-specific finite element (SS-FE) models and to evaluate the prediction accuracy of the models in relation to the model complexity. In total, SS-FE models of 31 femur specimens were developed. Using those models, dynamic three-point bending and combined loading tests (bending with four different levels of axial compression) of bare femurs were simulated, and the prediction capabilities of five different levels of model complexity were evaluated based on the impact force time histories: baseline, mass-based scaled, structure-based scaled, geometric SS-FE, and heterogenized SS-FE models. Among the five levels of model complexity, the geometric SS-FE and the heterogenized SS-FE models showed statistically significant improvement on response prediction capability compared to the other model formulations whereas the difference between two SS-FE models was negligible. This result indicated the geometric SS-FE models, containing detailed geometric information from CT images with homogeneous linear isotropic elastic material properties, would be an optimal model complexity for prediction of structural response of the femoral shafts under the dynamic loading conditions. The average and the standard deviation of the RMS errors of the geometric SS-FE models for all the 31 cases was 0.46 kN and 0.66 kN, respectively. This study highlights the contribution of geometric variability on the structural response variation of the femoral shafts subjected to dynamic loading condition and the potential of geometric SS-FE models to capture the structural response variation of the femoral shafts.     

Multifunctional Sensor Based on Translational‐Rotary Triboelectric Nanogenerator

Triboelectric nanogenerators with a large number of desirable advantages, such as flexibility, light weight, and easy integration, are unique for sensor design. In this paper, based on the triboelectric nanogenerator (TENG), a cylindrical self‐powered multifunctional sensor (MS) with a translational‐rotary magnetic mechanism is proposed, which has the capacity to detect acceleration, force, and rotational parameters. The MS can transform a translational motion into a swing motion or a multicircle rotational motion of a low damping magnetic cylinder around a friction layer and hence drives the TENG to generate voltages output. For enhancing the output performance of the TENG, an electrode material with small work function, low resistance, and suitable surface topography is the best choice. According to the structure characteristic of the translational‐rotary magnetic mechanism, the MS can easily respond to a weak striking and can be used to measure the rotational parameters without the need of coaxial installation. Based on the MS, some applications are established, for example measuring the punch acceleration of a boxer, the hitting force and swing angle of golf club, which demonstrate the feasibility and efficiency of the MS and exhibit that the MS could find applications in sports.     

Fatigue injury risk in anterior cruciate ligament of target side knee during golf swing

A golf-related ACL injury can be linked with excessive golf play or practice because such over-use by repetitive golf swing motions can increase damage accumulation to the ACL bundles. In this study, joint angular rotations, forces, and moments, as well as the forces and strains on the ACL of the target-side knee joint, were investigated for ten professional golfers using the multi-body lower extremity model. The fatigue life of the ACL was also predicted by assuming the estimated ACL force as a cyclic load. The ACL force and strain reached their maximum values within a short time just after ball-impact in the follow-through phase. The smaller knee flexion, higher internal tibial rotation, increase of the joint compressive force and knee abduction moment in the follow-through phase were shown as to lead an increased ACL loading. The number of cycles to fatigue failure (fatigue life) in the ACL might be several thousands. It is suggested that the excessive training or practice of swing motion without enough rest may be one of factors to lead to damage or injury in the ACL by the fatigue failure. The present technology can provide fundamental information to understand and prevent the ACL injury for golf players.     

Beryllium: genotoxicity and carcinogenicity

Beryllium (Be) has physical-chemical properties, including low density and high tensile strength, which make it useful in the manufacture of products ranging from space shuttles to golf clubs. Despite its utility, a number of standard setting agencies have determined that beryllium is a carcinogen. Only a limited number of studies, however, have addressed the underlying mechanisms of the carcinogenicity and mutagenicity of beryllium. Importantly, mutation and chromosomal aberration assays have yielded somewhat contradictory results for beryllium compounds and whereas bacterial tests were largely negative, mammalian test systems showed evidence of beryllium-induced mutations, chromosomal aberrations, and cell transformation. Although inter-laboratory differences may play a role in the variability observed in genotoxicity assays, it is more likely that the different chemical forms of beryllium have a significant effect on mutagenicity and carcinogenicity. Because workers are predominantly exposed to airborne particles which are generated during the machining of beryllium metal, ceramics, or alloys, testing of the mechanisms of the mutagenic and carcinogenic activity of beryllium should be performed with relevant chemical forms of beryllium.     

Seasonal phenology and diurnal activity of Promachus yesonicus (Diptera: Asilidae), a predator of scarabs,on Korean golf courses

The robber fly, Promachus yesonicus, a predator of scarab adults and larvae was observed on golf clubs in Korea to determine its seasonal activity, daily activity, and relationship to scarab adult activity. P. yesonicus adult density varied more than 10-fold among the four golf clubs where it was observed, with the most activity being at golf clubs with the most scarab adults in June and July. At Yongwon Golf Club P. yesonicus activity closely tracked Popillia quadriguttata activity and both peaked in late June and early July. The ratio of scarab adults (mostly P. quadriguttata):P. yesonicus adults was 8:1. On average mean of 7.5% of all P. yesonicus adults observed in visual surveys were holding captured prey. 50% of all captured prey was a scarab turf pest, P. quadriguttata. At Yongwon Golf Club, regression analysis indicates that P. quadriguttata activity explains 75% of the variation in activity of P. yesonicus. The potential impact of P. yesonicus on populations of P. quadriguttata and other scarab turf pests is discussed.     

PlexinA1 signaling directs the segregation of proprioceptive sensory axons in the developing spinal cord

As different classes of sensory neurons project into the CNS, their axons segregate and establish distinct trajectories and target zones. One striking instance of axonal segregation is the projection of sensory neurons into the spinal cord, where proprioceptive axons avoid the superficial dorsal horn-the target zone of many cutaneous afferent fibers. PlexinA1 is a proprioceptive sensory axon-specific receptor for sema6C and sema6D, which are expressed in a dynamic pattern in the dorsal horn. The loss of plexinA1 signaling causes the shafts of proprioceptive axons to invade the superficial dorsal horn, disrupting the organization of cutaneous afferents. This disruptive influence appears to involve the intermediary action of oligodendrocytes, which accompany displaced proprioceptive axon shafts into the dorsal horn. Our findings reveal a dedicated program of axonal shaft positioning in the mammalian CNS and establish a role for plexinA1-mediated axonal exclusion in organizing the projection pattern of spinal sensory afferents.     

Structure, mechanism and mechanical properties of pupal attachment in Greta oto (Lepidoptera: Nymphalidae: Ithomiinae)

The structure and mechanism of pupal attachment are described for the nymphalid Greta oto using electron microscopy, and high‐speed and time‐lapse photography. The cremaster is composed of a 3‐D array of hooked setae that engage with silk fibers spun into layers in a pad on the lower leaf surface. Each seta comprises a shaft terminating in a strongly curved hook, tipped with two lateral barbs. These hook into the silk pad, which is densely laid and built‐up in the central portion, flattening out peripherally. Time‐lapse photography showed that silk pad construction by fifth instar larvae is completed in four distinct spinning movements, producing a random fiber arrangement. It is proposed that such a fiber arrangement provides isotropic strength, giving greater flexibility to the attachment. The cremaster is attached to the silk pad by a series of lateral movements of the pupa's posterior abdomen. This movement, together with the shape of the setal hooks, is thought to be integral to the attachment process. Tensile loading tests showed that attachment failure is due to the breakage of the silk pad, which undergoes gradual destruction before releasing the cremaster. The attachment was found to have high tensile strength and fracture toughness, both of which suggest that it has evolved for the dual purpose of preventing the pupa being pulled from the leaf by a predator and preventing the attachment being weakened by wind, which causes the pupa to swing.     

A comparison of cortical bone thickness in the femoral midshaft of humans and two non-human mammals

Fragments of bone shafts that lack diagnostic features can be difficult to identify as human or non-human—an important task in forensic science and archaeology. Some workers have found the thickness of cortical bone in the shaft to be a useful distinction, although the sparse literature in the field is contradictory in how this may be applied.The aim of the present study was to determine whether any difference is discernible between humans, kangaroos and sheep (mammals whose remains are commonly confused with those of humans in Australia) at the femoral midshaft, with a view to a larger-scale analysis if differences were discovered. Cross-sections at the midpoint of the shaft were measured to determine the diameter of the whole shaft and the medullary cavity on each bone; an index describing cortical thickness relative to shaft diameter was calculated. Statistically significant differences were found between all three groups, with humans showing the thickest cortical bone, and sheep the thinnest. These differences may be linked to a higher load on the human femur, due to a larger body mass carried on two legs, as opposed to the sheep's four. Further work now needs to be carried out to determine if differences are present when comparing multiple sites on the skeleton, and between non-human mammals of different sizes.     

Increased trunk muscle recruitment during the golf swing is linked to developing lower back pain: A prospective longitudinal cohort study

BackgroundThis is the first study that presents electromyographic measurements prior to the development of lower back pain in young elite golfers.Study designProspective longitudinal cohort study.MethodsThirty-three injury free elite golfers were included. Muscle activity from latissimus dorsi, rectus abdominis, external oblique and erector spinae muscles were recorded during 10 drive golf swings. Lower back pain, training and performance were monitored over a six-month period. Muscle activation comparisons were made between the baseline results of those who went on to develop lower back pain versus those who did not go on to develop lower back pain.ResultsAfter the six-month monitoring period 17 participants developed lower back pain. The group that developed lower back pain had increased dominant rectus abdominis and dominant latissimus dorsi activation at various time points throughout the swing.DiscussionThe increased dominant rectus abdominis and dominant latissimus dorsi during the golf swing is linked with developing lower back pain. Training strategies aimed at reducing these muscles activation during the swing may reduce the incidence of lower back pain in young elite male golfers.     

The role of photoreception in the swarming behavior of the copepod Dioithona oculata

The copepod Dioithona oculata forms dense swarms near mangrove prop roots that are centered around shafts of light penetrating the mangrove canopy. Swarms can be created in the laboratory within light shafts created with a fiber optic light pipe. Laboratory observations of swarming behavior were recorded using video cameras, and the swimming behavior of the copepods and density of the swarms were quantified using video‐computer motion and image analysis techniques. Swarm formation results from a combination of phototactic and klino‐kinetic behavior. Dark adapted copepods initially exhibit a photophobic response to a light shaft, but become positively phototactic within 3–5 min after exposure to the light. Copepod aggregation rates under the light fit a saturation model, suggesting that copepods are attracted independently to the swarm marker. Copepods reverse their swimming direction when they encounter light intensity gradients near the edge of a light shaft, which aids in maintaining the swarm. Swarm formation can occur in the laboratory at light intensities as slow as 0.1 μM photons m^‐2 s^‐1, which is similar to light intensities at dawn when they are first observed to form in nature. Swarm formation appears to have an endogenous rhythm, as copepods will not form swarms at night under a light shaft.     

The impacts of abandoned mining shafts: Fauna entrapment in opal prospecting shafts at Coober Pedy, South Australia

Summary  The impacts of uncapped, abandoned mining shafts on small vertebrate species were investigated by monitoring numbers of fauna falling into opal prospecting shafts near Coober Pedy, in the far north of South Australia. Catching devices made from 10 L buckets were installed in the top of 43 shafts and checked regularly by local community members for a total of 10 840 trap nights over a 13-month period. A total of 190 individual reptiles of 18 species were captured in this manner after falling into shafts, including the nationally vulnerable Bronzeback Legless Lizard ( Ophidiocephalus taeniatus ). While the tops of these shafts resemble conventional pitfall traps used in scientific monitoring and therefore readily 'trap' ground-fauna, they may be over 30 m deep and are permanently open. Capture rates in this study, calculated at 4.1 reptiles / shaft / year, highlight the potential impact of the similar shafts that remain uncapped in the Coober Pedy opal fields, roughly estimated to be anywhere from 1 to 2 million shafts. The inferred total number of captures from these shafts may represent 10–28 million reptiles / year or an equivalent of 25–72 tonnes of biomass. The results highlight the potential threat that uncapped shafts may pose to Bronzeback Legless Lizard populations in this area and suggest that they may also have major impacts on other small vertebrate fauna in the Coober Pedy area and in other similar opal mining areas.     

毛干DNA提取方法概述

毛干作为最容易取得的一种无创、运输和储存方便的生物样本,对从核酸分子水平上进行各方面研究有着十分重要的意义。但毛干中DNA含量低,不易提取,而且存在大量角蛋白和色素,纯化不净会对下游PCR扩增等反应产生抑制作用。基于毛干DNA提取现状,综述并比较了近三十年动物及人类毛发的毛干DNA提取、纯化等相关方法,拟为毛干DNA提取在分子生物学各领域的推广应用提供充分的文献支持和参考。