Linear Relationships Among the Hand and Clubhead Motion Characteristics in Golf Driving in Skilled Male Golfers.

The purpose of this study was to investigate the linear relationships among the hand/clubhead motion characteristics in golf driving in skilled male golfers (n = 66; handicap ≤ 3). The hand motion plane (HMP) and functional swing plane (FSP) angles, the HMP-FSP angle gaps, the planarity characteristics of the off-plane motion of the clubhead, and the attack angles were computed from the drives captured by an optical motion capture system. The HMP angles were identified as the key variables, as the HMP and FSP angles were intercorrelated, but the plane angle gaps, the planarity bias, and the attack angles showed correlations to the HMP angles primarily. Three main swing pattern clusters were identified. The parallel HMP-FSP alignment pattern with a small direction gap was associated with neutral planarity and planar swing pattern. The inward alignment pattern with a large inward direction gap was characterized by flat planes, follow-through-centric planarity, spiral swing pattern, and inward/downward impact. The outward alignment pattern with a large outward direction gap was associated with steep planes, downswing-centric planarity, reverse spiral swing, and outward/upward impact. The findings suggest that practical drills targeting the hand motion pattern can be effective in holistically reprogramming the swing pattern.

Gender-Based Correlation Profiles Among the Release Factors and Distance Thrown in Paralympic Seated Shot Put.

The purpose of this study was to investigate the relationships among release factors (speed, height, and angle) and distance thrown in Paralympic seated shot put. Forty-eight trials performed by 11 men and 5 women during the 2012 US Paralympic trials in track and field were analyzed. With both genders combined, release speed (r = .95, p < .01) and angle (r = .51, p < .01) showed significant correlations to distance thrown. Release speed (r = .94, p < .01) in men and all release factors (r = .60-.98, p < .02) in women showed significant correlations to distance. Release speed and angle were identified as important predictors of the distance, explaining over 89-96% of the variance in distance thrown. Unlike athletes without disability, seated shot-putters exhibited significant positive speed-angle correlations (combined: r = .37, p < .01; women: r = .57, p = .03). Application of these results should address a focus in training on generating speed through the release point with a consistent release angle.

Generation of vertical angular momentum in single, double, and triple-turn pirouette en dehors in ballet.

The purpose of this study was to investigate the vertical angular momentum generation strategies used by skilled ballet dancers in pirouette en dehors. Select kinematic parameters of the pirouette preparation (stance depth, vertical center-of-mass motion range, initial shoulder line position, shoulder line angular displacement, and maximum trunk twist angle) along with vertical angular momentum parameters during the turn (maximum momentums of the whole body and body parts, and duration and rate of generation) were obtained from nine skilled collegiate ballet dancers through a three-dimensional motion analysis and compared among three turn conditions (single, double, and triple). A one-way ('turn') multivariate analysis of variance of the kinematic parameters and angular momentum parameters of the whole body and a two-way analysis of variance ('turn' × 'body') of the maximum angular momentums of the body parts were conducted. Significant 'turn' effects were observed in the kinematic/angular momentum parameters (both the preparation and the turn) (p <  0.05). As the number of turns increased, skilled dancers generated larger vertical angular momentums by predominantly increasing the rate of momentum generation using rotation of the upper trunk and arms. The trail (closing) arm showed the largest contribution to whole-body angular momentum followed by the lead arm.

Effects of two-step golf swing drills on rhythm and clubhead speed in competitive juniors.

Vertical and horizontal rhythms are crucial aspects of a dynamic golf swing, and the two-step swing drills (TSSD) were specifically designed to promote rhythmic unloading and loading of the legs. The purpose of this study was to evaluate the effects of a TSSD training session on the swing rhythm and clubhead speed (CHS) among competitive junior golfers (3.1 ± 4.4 hcp). The driver swings (7 swings each) of 10 competitive junior golfers (aged 15-18) were captured before and after a TSSD session consisting of four stages (lasting less than 45 minutes). Post-TSSD training, there were significant increases in CHS (p < .001), maximum unweighting (p = .006), the trail-side push (p = .009), the horizontal motion ranges of the body and pelvis (p = .005-.031), the upward/downward motion range of the body in the backswing (p = .042/.024), and the backswing/downswing angular velocity peaks of the axle-chain system (p < .033). The stepping-like leg actions primarily facilitated horizontal motion rhythm over vertical motion and unweighting over push in terms of ground interaction. These findings suggest that TSSD can serve as an effective method for developing a rhythmic and dynamic motion pattern while increasing CHS.

Validity of the X-factor computation methods and relationship between the X-factor parameters and clubhead velocity in skilled golfers.

The purpose of this study was to assess the validity of the X-factor computation methods and to examine whether direct relationships exist between the X-factor parameters and the clubhead velocity in a group of skilled male golfers (n = 18, handicap = -0.6 +/- 2.1). Five driver trials were captured from each golfer using an optical motion capture system (250 Hz). Two plane-based methods (conventional vs. functional swing plane-based) and one Cardan rotation-based method (relative orientation) were used to compute select X-factor (end of pelvis rotation, top of backswing, ball impact (BI), and maximum), X-factor stretch (stretch and maximum stretch), and X-factor velocity (BI and maximum) parameters. The maximum clubhead velocity was extracted and normalized to golfer's body height to eliminate the effect of body size. A one-way repeated MANOVA revealed that the computation methods generated significantly different X-factor parameter values (p < 0.001). The conventional method provided substantially larger X-factor values than the other methods in the untwisting phase and the meaningfulness of select X-factor parameters generated by this method was deemed questionable. The correlation analysis revealed that the X-factor parameters were not directly related to the maximum clubhead velocity (both unnormalized and normalized).

Biomechanical effects of fatigue on lower-body extremities during a maximum effort kettlebell swing protocol.

Kettlebell training provides multiple health benefits, including the generation of power. The primary purpose of this study was to examine the kinematics and kinetics of lower-body joints during a repeated, maximum effort kettlebell swing protocol. Sixteen resistance and kettlebell swing experienced males performed 10 rounds of a kettlebell swing routine (where one round equates to 30s of swings followed by 30s of rest). Kinematic (i.e., swing duration and angular velocities) and kinetic (i.e., normalised sagittal plane ground reaction force, resultant joint moment [RJM] and power) variables were extracted for the early portion and late portion of the round. Average swing duration and the magnitude of normalised ground reaction forces (GRF) increased within rounds, while hip joint power decreased. Changes in swing duration were minimal, but consistent due to an increase in overall fatigue. An increase in the magnitude of GRF was observed at the end of rounds, which is a potential concern for injury. Hip joint power decreased primarily due to a slower angular velocity. This protocol may be an effective routine for those who are resistance trained with kettlebell swing experience, and who want to optimise power in their exercise program.

The effects of railroad ballast surface and slope on rearfoot motion in walking.

The purpose of this study was to investigate the effects of transversely sloped ballasted walking surface on gait and rearfoot motion (RFM) parameters. Motion analysis was performed with 20 healthy participants (15 male and 5 female) walking in six surface-slope conditions: two surfaces (solid and ballasted) by three slopes (0, 5, and 10 degrees). The gait parameters (walking velocity, step length, step rate, step width, stance time, and toe-out angle) showed significant surface effect (p = .004) and surface-slope interaction (p = .017). The RFM motion parameters (peak everted/inverted position, eversion/inversion velocity, and acceleration) revealed significant surface (p = .004) and slope (p = .024) effects. The ballasted conditions showed more cautious gait patterns with lower walk velocity, step length, and step rate and longer stance time. In the RFM parameters, the slope effect was more notable in the solid conditions due to the gait adaptations in the ballasted conditions. Ballast conditions showed reduced inversion and increased eversion and RFM range. The RFM data were comparable to other typical walking conditions but smaller than those from running.

Assessment of planarity of the golf swing based on the functional swing plane of the clubhead and motion planes of the body points.

The purposes of this study were (1) to determine the functional swing plane (FSP) of the clubhead and the motion planes (MPs) of the shoulder/arm points and (2) to assess planarity of the golf swing based on the FSP and the MPs. The swing motions of 14 male skilled golfers (mean handicap = -0.5 +/- 2.0) using three different clubs (driver, 5-iron, and pitching wedge) were captured by an optical motion capture system (250Hz). The FSP and MPs along with their slope/relative inclination and direction/direction of inclination were obtained using a new trajectory-plane fitting method. The slope and direction of the FSP revealed a significant club effect (p < 0.001). The relative inclination and direction of inclination of the MP showed significant point (p < 0.001) and club (p < 0.001) effects and interaction (p < 0.001). Maximum deviations of the points from the FSP revealed a significant point effect (p < 0.001) and point-club interaction (p < 0.001). It was concluded that skilled golfers exhibited well-defined and consistent FSP and MPs, and the shoulder/arm points moved on vastly different MPs and exhibited large deviations from the FSP. Skilled golfers in general exhibited semi-planar downswings with two distinct phases: a transition phase and a planar execution phase.

Is Golf a Contact Sport? Protection of the Spine and Return to Play After Lumbar Surgery.

STUDY DESIGN: Narrative review. OBJECTIVE: To address the gap in the literature on specific return to play protocols and rehabilitation regimens for golfers undergoing lumbar spine surgery with a high impact swing. METHODS: This review did not involve patient care or any clinical prospective or retrospective review of patient information and thus did not warrant institutional review board approval. The available literature of PubMed, Medline, and OVID was utilized to review the existing literature. RESULTS: Studies have shown that the forces through the lumbar spine in the modern-era golf swing are like other contact sports. Methods of protecting the lumbar spine include proper swing mechanics, abdominal and paraspinal musculature strengthening and flexibility as well as physical fitness. There are a variety of treatment options available to treat lumbar spine pathology each with a different return to play recommendations from doctors in the field. CONCLUSIONS: With the introduction of a high impact, modern-era swing to the game of golf, the pathology is seen in the lumbar spine of both young, old, professional, and amateur golfers with low back pain are similar to other athletes in contact sports. Surgery is effective in returning athletes to a similar level of play even though no protocols exist for an effective and safe return. There have been many studies conducted to determine appropriate treatment and return to play for these injuries, but there is a gap in the literature on specific return to play protocols and rehabilitation regimens for golfers undergoing lumbar spine surgery with a high impact swing. As return to competitive play is important, especially with professional golfers, studies combining the use of swing mechanics changes, rehabilitation regimens and the type of surgery performed would be able to provide some insight into this topic now that golf may begin to be considered a contact sport.

Effects of kettlebell mass on lower-body joint kinetics during a kettlebell swing exercise.

Functional training aims to provide specific adaptations due to exercise training and utilises a variety of equipment, including kettlebells. Due to the training principle of overload, a greater resistance must be applied to yield increased strength results. This study examined the effects of kettlebell mass on lower body joint kinetics in young recreationally trained adults. Thirty recreationally active, college-aged adults were recruited for this study. Participants performed hip-hinge style swings with kettlebells equivalent to 10%, 15% and 20% of their respective body mass. 3-D marker coordinate data were captured via infrared camera system and ground reaction force data were measured with two force plates. The resultant joint moments of the lower body were calculated using the inverse dynamics procedure. As mass increased, there was an increase in joint moment at the L4/5, hip and ankle joint, primarily due to an increase in ground reaction force. Increasing kettlebell mass can potentially cause greater strength gains in the hip and trunk musculature due to increase in lower body moments, while avoiding excessive moments about the knee.

Kinematic motion of the windmill softball pitch in prepubescent and pubescent girls.

This study examined the joint motions and movement patterns of the kinetic chain in the ballistic skill of performing the windmill pitch. Seventeen healthy girls who were currently playing competitive fast-pitch softball volunteered for the study. Subjects were instructed to perform 5 successful fastball windmill style deliveries. We selected 1 pitch for analysis based on the velocity, accuracy, and subjects' input. Kwon3D motion analysis package (Visol., Inc., Seoul, Korea), with 6 digital camcorders placed at 60 degrees apart was used for analysis. Raw data were interpolated using a frequency of 60 Hz and then smoothed using Butterworth low-pass second-order filter with a fixed cut-off frequency of 6 Hz. The subjects were divided into groups based on skill level: novice, intermediate, and advanced. Sequential progression of kinematic variables that resulted in increased throwing velocity and the contribution each segment (upper arm, forearm, and hand) possessed toward ball velocity with descriptive statistics and path analysis were assessed. There was evidence of sequentiality among the arm segments in the intermediate and advanced groups. The patterns of the shared positive contributions made by each of the limb segments were similar among the 3 groups of participants. The novice group tended to rely on more of the upper arm and forearm than the other 2 groups. From this study, it is evident that all emphasis should not be placed on the shoulder, but training and conditioning methods should focus on the entire kinetic chain including the torso and the full arm segment, not just the shoulder in an attempt to gain the greatest velocity while performing the 360 degrees arc of the windmill softball pitch.

A combined method for binning coupling angles to define coordination patterns.

The vector coding technique has been used to quantify coordination of two joints, segments, and/or planes during cyclic activities, such as walking. Coordination patterns can be identified by categorizing the tangent lines of an angle-angle plot by their direction, termed "coupling angle binning" or "phase binning". In the literature the ranges of directions, or "bins", originally divided by Chang et al. and more recently by Needham et al. have different strengths. Chang's method identifies general patterns with large bins while Needham's method identifies a dominant joint or segment in the pattern. This study created a novel method that incorporates bin categories from both methods, and therefore recognizes both general patterns and a dominant contributor when appropriate. This new method, the SRC method, as well as the two existing methods, were used to quantify knee-ankle coordination in the sagittal plane for healthy individuals and an individual with clubfoot during gait. Similarities and differences in classification between methods were compared and further investigated by interpreting the uncoupled angular data. Each method was then used to evaluate sagittal-coronal coordination of the forefoot in an individual with clubfoot during gait. This was done to demonstrate across-plane coordination analysis, to confirm that the advantages of the combined method extend to coupling pairs with like ranges of motion, and to present a clinical application. It was found that the TSRH binning methods provides a more complete description of coordination by including coordination categories defined by both the Chang and Needham method.

Effects of pelvis-shoulders torsional separation style on kinematic sequence in golf driving.

The golfer's body (trunk/arms/club) can be modeled as an inclined axle-chain system and the rotations of its parts observed on the functional swing plane (FSP) can represent the actual angular motions closely. The purpose of this study was to investigate the effects of pelvis-shoulders torsional separation style on the kinematic sequences employed by the axle-chain system in golf driving. Seventy-four male skilled golfers (handicap ≤ 3) were assigned to five groups based on their shoulder girdle motion and X-factor stretch characteristics: Late Shoulder Acceleration, Large Downswing Stretch, Large Backswing Stretch, Medium Total Stretch, and Small Total Stretch. Swing trials were captured by an optical system and the hip-line, thorax, shoulder-line, upper-lever, club, and wrist angular positions/velocities were calculated on the FSP. Kinematic sequences were established based on the timings of the peak angular velocities (backswing and downswing sequences) and the backswing-to-downswing transition time points (transition sequence). The backswing and transition sequences were somewhat consistent across the groups, showing full or partial proximal-to-distal sequences with minor variations. The downswing sequence was inconsistent across the groups and the angular velocity peaks of the body segments were not significantly separated. Various swing characteristics associated with the separation styles influenced the motion sequences.

Effects of the golfer-ground interaction on clubhead speed in skilled male golfers.

The purposes of this study were to characterise the golfer-ground interactions during the swing and to identify meaningful associations between the golfer-ground interaction force/moment parameters and the maximum clubhead speed in 63 highly skilled male golfers (handicap ≤ 3). Golfers performed shots in 3 club conditions (driver, 5-iron and pitching wedge) which were captured by an optical motion capture system and 2 force plates. In addition to the ground reaction forces (GRFs), 3 different golfer-ground interaction moments (GRF moments, pivoting moments and foot contact moments) were computed. The GRF moment about the forward/backward (F/B) axis and the pivoting moment about the vertical axis were identified as the primary moments. Significant (p < 0.05) correlations of peak force parameters (all components in the lead foot and F/B component in the trail foot) and peak moment parameters (lead-foot GRF moment and trail-foot pivoting moment) to clubhead speed were found. The lead-foot was responsible for generating the GRF moment, while the trail foot contributed to the pivoting moment more. The instant the lead arm becomes parallel to the ground was identified as the point of maximum angular effort, and the loading onto the lead-foot near this point was critical in generating both peak moments.

Blueberries Improve Pain, Gait Performance, and Inflammation in Individuals with Symptomatic Knee Osteoarthritis.

Osteoarthritis (OA) is the most common joint disorder in the world and is the most frequent cause of walking related disability among older adults in the US, which brings a significant economic burden and reduces quality of life. The initiation and development of OA typically involves degeneration or progressive loss of the structure and function of articular cartilage. Inflammation is one of the major drives of the progression of OA. Dietary polyphenols have been studied for their anti-inflammatory properties and potential anabolic effects on the cartilage cells. Blueberries are widely consumed and are high in dietary polyphenols, therefore regular consumption of blueberries may help improve OA. The purpose of the present study was to examine the effect of freeze dried whole blueberries on pain, gait performance, and inflammation in individuals with symptomatic knee OA. In a randomized, double-blind trial, adults age 45 to 79 with symptomatic knee OA, were randomized to either consume 40 g freeze-dried blueberry powder (n = 33) or placebo powder (n = 30) daily for four months. Blood draws and assessment of pain and gait were conducted at baseline, two months, and four months. Western Ontario McMaster Osteoarthritis Index (WOMAC) questionnaires were used to assess pain and GAITRite® electronic walkway was used to evaluate gait spatiotemporal parameters. WOMAC total score and sub-groups, including pain, stiffness, and difficulty to perform daily activities decreased significantly in the blueberry treatment group (p < 0.05), but improvement of WOMAC total score and difficulty to perform daily activities were not observed in the placebo group. Normal walking pace single support percentage for both limbs increased (p = or < 0.007), while double support percentage for both limbs decreased in the blueberry treatment group (p = or < 0.003). No significant changes were observed in plasma concentrations of tumor necrosis factor (TNF)-α, interleukin (IL)-1ß, IL-6, IL-10, IL-13, matrix metalloproteinases (MMP)-3, MMP-13, and monocyte chemoattractant protein-1 (MCP-1) in both treatment groups. However, an increasing trend for IL-13 concentration and a decreasing trend in MCP-1 concentration were noted in the blueberry group. The findings of this study suggest that daily incorporation of whole blueberries may reduce pain, stiffness, and difficulty to perform daily activities, while improving gait performance, and would therefore improve quality of life in individuals with symptomatic knee OA.

Accuracy of sequential sub-field synchronization of multiple digital camcorders through numerical optimization.

The use of digital camcorders in biomechanical analyses can introduce errors due to inter-camera time offsets. The faster the motion being recorded the greater the error. A sequential synchronization method was developed in this study to achieve sub-field camera synchronization for multiple camcorders through numerical optimization. A recreational golfer performed ten drives while being recorded with four digital camcorders (60-Hz sampling rate). Video signals were sampled at 10,000 Hz to determine the actual inter-camera time offsets. The optimized inter-camera time offsets were computed based on three markers placed on the shaft, each separated by 200 mm. The inter-camera time offset error was computed as the difference between the optimized and actual inter-camera time offsets. The inter-camera time offset error reduced on average from 0.518 to 0.019 fields (1 field = 16.7 ms) or less due to sequential optimization. The optimized global reconstruction errors were less than 19% of the unadjusted values. It was concluded that the ability to synchronize multiple (two or more) cameras using a sequential sub-field optimization strategy promises to extend the use of relatively inexpensive digital camcorders to motions considered too fast for the low field rates of such cameras. The sequential approach presented provides a balance between computation time and reconstruction accuracy.

Effects of light refraction on the accuracy of camera calibration and reconstruction in underwater motion analysis.

One of the most serious obstacles to accurate quantification of the underwater motion of a swimmer's body is image deformation caused by refraction. Refraction occurs at the water-air interface plane (glass) owing to the density difference. Camera calibration-reconstruction algorithms commonly used in aquatic research do not have the capability to correct this refraction-induced nonlinear image deformation and produce large reconstruction errors. The aim of this paper is to provide a through review of: the nature of the refraction-induced image deformation and its behaviour in underwater object-space plane reconstruction; the intrinsic shortcomings of the Direct Linear Transformation (DLT) method in underwater motion analysis; experimental conditions that interact with refraction; and alternative algorithms and strategies that can be used to improve the calibration-reconstruction accuracy. Although it is impossible to remove the refraction error completely in conventional camera calibration-reconstruction methods, it is possible to improve the accuracy to some extent by manipulating experimental conditions or calibration frame characteristics. Alternative algorithms, such as the localized DLT and the double-plane method are also available for error reduction. The ultimate solution for the refraction problem is to develop underwater camera calibration and reconstruction algorithms that have the capability to correct refraction.

Effects of light refraction on the accuracy of camera calibration and reconstruction in underwater motion analysis.

One of the most serious obstacles to accurate quantification of the underwater motion of a swimmer's body is image deformation caused by refraction. Refraction occurs at the water-air interface plane (glass) owing to the density difference. Camera calibration-reconstruction algorithms commonly used in aquatic research do not have the capability to correct this refraction-induced nonlinear image deformation and produce large reconstruction errors. The aim of this paper is to provide a thorough review of: the nature of the refraction-induced image deformation and its behaviour in underwater object-space plane reconstruction; the intrinsic shortcomings of the Direct Linear Transformation (DLT) method in underwater motion analysis; experimental conditions that interact with refraction; and alternative algorithms and strategies that can be used to improve the calibration-reconstruction accuracy. Although it is impossible to remove the refraction error completely in conventional camera calibration-reconstruction methods, it is possible to improve the accuracy to some extent by manipulating experimental conditions or calibration frame characteristics. Alternative algorithms, such as the localized DLT and the double-plane method are also available for error reduction. The ultimate solution for the refraction problem is to develop underwater camera calibration and reconstruction algorithms that have the capability to correct refraction.