Sean Horan

Thorax and pelvis kinematics during the downswing of male and female skilled golfers

Thorax and pelvis motion during the golf swing have most frequently been described for male golfers at discrete points during the swing, such as top of backswing (TBS) and ball contact (BC). Less is known about the continual motion and coordination of the thorax and pelvis throughout the downswing for either male or female golfers. The purpose of this study was to present detailed 3D kinematic profiles of thorax and pelvis motion during the downswing, and to determine if differences in kinematics exist between male and female skilled golfers. Thorax and pelvis data were collected from 19 male (26+/-7 years) and 19 female (25+/-7 years) skilled golfers (handicap < or =4) using an optical motion analysis system. 3D segment position, orientation and angular velocity were calculated, along with phase plane trajectories and thorax-pelvis separation angles. At BC males had greater pelvis posterior tilt, greater pelvis and thorax lateral tilt to the right, and less pelvis and thorax axial rotation to the left compared to females. Males achieved greater peak thorax and pelvis angular velocity, and angular velocity at BC, in the anterior-posterior and lateral tilt directions. Phase plane trajectories revealed that males and females had similar thorax lateral tilt and anterior-posterior tilt angular velocity-displacement relationships at TBS, yet by BC males had greater tilt angles and velocities compared to females. Collectively, the results suggest that male and female skilled golfers have different kinematics for thorax and pelvis motion, predominantly for lateral and anterior-posterior tilt. What might be considered optimal swing characteristics for male golfers should not be generalized to female golfers.

Movement Variability in the Golf Swing of Male and Female Skilled Golfers

BACKGROUND Despite the complexity of movement, the swings of skilled golfers are considered to be highly consistent. Interestingly, no direct investigation of movement variability or coupling variability during the swings of skilled golfers has occurred. PURPOSE To determine whether differences in movement variability exist between male and female skilled golfers during the downswing of the full golf swing. METHODS Three-dimensional thorax, pelvis, hand, and clubhead data were collected from 19 male (mean ± SD: age = 26 ± 7 yr) and 19 female (age = 25 ± 7 yr) skilled golfers. Variability of segmental movement and clubhead trajectory were examined at three phases of the downswing using discrete (SD) and continuous analyses (spanning set), whereas variability of intersegment coupling was examined using average coefficient of correspondence. RESULTS Compared with males, females exhibited higher thorax and pelvis variability for axial rotation at the midpoint of the downswing and ball contact (BC). Similarly, thorax-pelvis coupling variability was higher for females than males at both the midpoint of the downswing and BC. Regardless of thorax and pelvis motion, the variability of hand and clubhead trajectory sequentially decreased from the top of the backswing to BC for both males and females. CONCLUSIONS Male and female skilled golfers use different upper body movement strategies during the downswing while achieving similarly low levels of clubhead trajectory variability at BC. It is apparent that the priority of skilled golfers is to progressively minimize hand and clubhead trajectory variability toward BC, despite the individual motion or coupling of the thorax and pelvis.

The control of upper body segment speed and velocity during the golf swing

Understanding the dynamics of upper body motion during the downswing is an important step in determining the control strategies required for a successful and repeatable golf swing. The purpose of this study was to examine the relationship between head, thorax, and pelvis motion, during the downswing of professional golfers. Three-dimensional data were collected for 14 male professional golfers (age 27 ± 8 years, golf-playing experience 13.3 ± 8 years) using an optical motion analysis system. The amplitude and timing of peak speed and peak velocities were calculated for the head, thorax, and pelvis during the downswing. Cross-correlation analysis was used to examine the strength of coupling and phasing between and within segments. The results indicated the thorax segment had the highest peak speeds and peak velocities for the upper body during the downswing. A strong coupling relationship was evident between the thorax and pelvis (average R 2 = 0.92 across all directions), while the head and thorax showed a much more variable relationship (average R 2 = 0.76 across all directions). The strong coupling between the thorax and pelvis is possibly a method for simplifying the motor control strategy used during the downswing, and a way of ensuring consistent motor patterns.

Kinematic predictors of single-leg squat performance: a comparison of experienced physiotherapists and student physiotherapists

BackgroundThe single-leg squat (SLS) is a common test used by clinicians for the musculoskeletal assessment of the lower limb. The aim of the current study was to reveal the kinematic parameters used by experienced and inexperienced clinicians to determine SLS performance and establish reliability of such assessment.MethodsTwenty-two healthy, young adults (23.8 ± 3.1 years) performed three SLSs on each leg whilst being videoed. Three-dimensional data for the hip and knee was recorded using a 10-camera optical motion analysis system (Vicon, Oxford, UK). SLS performance was rated from video data using a 10-point ordinal scale by experienced musculoskeletal physiotherapists and student physiotherapists. All ratings were undertaken a second time at least two weeks after the first by the same raters. Stepwise multiple regression analysis was performed to determine kinematic predictors of SLS performance scores and inter- and intra-rater reliability were determined using a two-way mixed model to generate intra-class correlation coefficients (ICC3,1) of consistency.ResultsOne SLS per leg for each participant was used for analysis, providing 44 SLSs in total. Eight experienced physiotherapists and eight physiotherapy students agreed to rate each SLS. Variance in physiotherapist scores was predicted by peak knee flexion, knee medio-lateral displacement, and peak hip adduction (R2 = 0.64, p = 0.01), while variance in student scores was predicted only by peak knee flexion, and knee medio-lateral displacement (R2 = 0.57, p = 0.01). Inter-rater reliability was good for physiotherapists (ICC3,1 = 0.71) and students (ICC3,1 = 0.60), whilst intra-rater reliability was excellent for physiotherapists (ICC3,1 = 0.81) and good for students (ICC3,1 = 0.71).ConclusionPhysiotherapists and students are both capable of reliable assessment of SLS performance. Physiotherapist assessments, however, bear stronger relationships to lower limb kinematics and are more sensitive to hip joint motion than student assessments.

High‐Intensity Resistance and Impact Training Improves Bone Mineral Density and Physical Function in Postmenopausal Women With Osteopenia and Osteoporosis: The LIFTMOR Randomized Controlled Trial

Optimal osteogenic mechanical loading requires the application of high‐magnitude strains at high rates. High‐intensity resistance and impact training (HiRIT) applies such loads but is not traditionally recommended for individuals with osteoporosis because of a perceived high risk of fracture. The purpose of the LIFTMOR trial was to determine the efficacy and to monitor adverse events of HiRIT to reduce parameters of risk for fracture in postmenopausal women with low bone mass. Postmenopausal women with low bone mass (T‐score < –1.0, screened for conditions and medications that influence bone and physical function) were recruited and randomized to either 8 months of twice‐weekly, 30‐minute, supervised HiRIT (5 sets of 5 repetitions, >85% 1 repetition maximum) or a home‐based, low‐intensity exercise program (CON). Pre‐ and post‐intervention testing included lumbar spine and proximal femur bone mineral density (BMD) and measures of functional performance (timed up‐and‐go, functional reach, 5 times sit‐to‐stand, back and leg strength). A total of 101 women (aged 65 ± 5 years, 161.8 ± 5.9 cm, 63.1 ± 10.4 kg) participated in the trial. HiRIT (n = 49) effects were superior to CON (n = 52) for lumbar spine (LS) BMD (2.9 ± 2.8% versus –1.2 ± 2.8%, p < 0.001), femoral neck (FN) BMD (0.3 ± 2.6% versus –1.9 ± 2.6%, p = 0.004), FN cortical thickness (13.6 ± 16.6% versus 6.3 ± 16.6%, p = 0.014), height (0.2 ± 0.5 cm versus –0.2 ± 0.5 cm, p = 0.004), and all functional performance measures (p < 0.001). Compliance was high (HiRIT 92 ± 11%; CON 85 ± 24%) in both groups, with only one adverse event reported (HiRIT: minor lower back spasm, 2/70 missed training sessions). Our novel, brief HiRIT program enhances indices of bone strength and functional performance in postmenopausal women with low bone mass. Contrary to current opinion, HiRIT was efficacious and induced no adverse events under highly supervised conditions for our sample of otherwise healthy postmenopausal women with low to very low bone mass.

Repeatability of three-dimensional thorax and pelvis kinematics in the golf swing measured using a field-based motion capture system

Field-based methods of evaluating three-dimensional (3D) swing kinematics offer coaches and researchers the opportunity to assess golfers in context-specific environments. The purpose of this study was to establish the inter-trial, between-tester, between-location, and between-day repeatability of thorax and pelvis kinematics during the downswing using an electromagnetic motion capture system. Two experienced testers measured swing kinematics in 20 golfers (handicap ≤ 14 strokes) on consecutive days in an indoor and outdoor location. Participants performed five swings with each of two clubs (five-iron and driver) at each test condition. Repeatability of 3D kinematic data was evaluated by computing the coefficient of multiple determination (CMD) and the systematic error (SE). With the exception of pelvis forward bend for between-day and between-tester conditions, CMDs exceeded 0.854 for all variables, indicating high levels of overall waveform repeatability across conditions. When repeatability was compared across conditions using MANOVA, the lowest CMDs and highest SEs were found for the between-tester and between-day conditions. The highest CMDs were for the inter-trial and between-location conditions. The absence of significant differences in CMDs between these two conditions supports this method of analysing pelvis and thorax kinematics in different environmental settings without unduly affecting repeatability.

A video-based learning activity is effective for preparing physiotherapy students for practical examinations

OBJECTIVES To examine a video-based learning activity for engaging physiotherapy students in preparation for practical examinations and determine student performance outcomes. DESIGN Multi-method employing qualitative and quantitative data collection procedures. SETTING Tertiary education facility on the Gold Coast, Queensland, Australia. PARTICIPANTS Physiotherapy students in their first year of a two-year graduate entry program. MAIN OUTCOME MEASURES Questionnaire-based surveys and focus groups were used to examine student perceptions and satisfaction. Surveys were analysed based on the frequency of responses to closed questions made on a 5-pont Likert scale, while a thematic analysis was performed on focus group transcripts. t-Tests were used to compare student awarded marks and examiner awarded marks and evaluate student performance. RESULTS Sixty-two physiotherapy students participated in the study. Mean response rate for questionnaires was 93% and eight students (13%) participated in the focus group. Participants found the video resources effective to support their learning (98% positive) and rating the video examples to be an effective learning activity (96% positive). Themes emergent from focus group responses were around improved understanding, reduced performance anxiety, and enjoyment. Students were, however, critical of the predictable nature of the example performances. Students in the current cohort supported by the video-based preparation activity exhibited greater practical examination marks than those from the previous year who were unsupported by the activity (mean 81.6 SD 8.7 vs. mean 78.1 SD 9.0, p=0.01). CONCLUSION A video-based learning activity was effective for preparing physiotherapy students for practical examinations and conferred benefits of reduced anxiety and improved performance.

Lower-limb kinematics of single-leg squat performance in young adults.

PURPOSE To determine the kinematic parameters that characterize good and poor single-leg squat (SLS) performance. METHODS A total of 22 healthy young adults free from musculoskeletal impairment were recruited for testing. For each SLS, both two-dimensional video and three-dimensional motion analysis data were collected. Pelvis, hip, and knee angles were calculated using a reliable and validated lower-limb (LL) biomechanical model. Two-dimensional video clips of SLSs were blindly assessed in random order by eight musculoskeletal physiotherapists using a 10-point ordinal scale. To facilitate between-group comparisons, SLS performances were stratified by tertiles corresponding to poor, intermediate, and good SLS performance. RESULTS Mean ratings of SLS performance assessed by physiotherapists were 8.3 (SD 0.5), 6.8 (SD 0.7), and 4.0 (SD 0.8) for good, intermediate, and poor squats, respectively. Three-dimensional analysis revealed that people whose SLS performance was assessed as poor exhibited increased hip adduction, reduced knee flexion, and increased medio-lateral displacement of the knee joint centre compared to those whose SLS performance was assessed as good (p≤0.05). CONCLUSIONS Overall, poor SLS performance is characterized by inadequate knee flexion and excessive frontal plane motion of the knee and hip. Future investigations of SLS performance should consider standardizing knee flexion angle to illuminate other influential kinematic parameters.

Muscle Size Not Density Predicts Variance in Muscle Strength and Neuromuscular Performance in Healthy Adult Men and Women.

Abstract Weeks, BK, Gerrits, TAJ, Horan, SA, and Beck, BR. Muscle size not density predicts variance in muscle strength and neuromuscular performance in healthy adult men and women. J Strength Cond Res 30(6): 1577–1584, 2016—The purpose of this study was to determine the relationships between peripheral quantitative computed tomography (pQCT)–derived measures of muscle area and density and markers of muscle strength and performance in men and women. Fifty-two apparently healthy adults (26 men, 26 women; age 33.8 ± 12.0 years) volunteered to participate. Dual-energy x-ray absorptiometry (XR-800; Norland Medical Systems, Inc., Trumbull, CT, USA) was used to determine whole body and regional lean and fat tissue mass, whereas pQCT (XCT-3000; Stratec, Pforzheim, Germany) was used to determine muscle cross-sectional area (MCSA) and muscle density of the leg, thigh, and forearm. Ankle plantar flexor and knee extensor strengths were examined using isokinetic dynamometry, and grip strength was examined with dynamometry. Impulse generated during a maximal vertical jump was used as an index of neuromuscular performance. Thigh, forearm, and leg MCSA strongly predicted variance in knee extensor (R 2 = 0.77, p < 0.001) and grip strength (R 2 = 0.77, p < 0.001) and weakly predicted variance in ankle plantar flexor strength (R 2 = 0.20, p < 0.001), respectively, whereas muscle density was only a weak predictor of variance in knee extensor strength (R 2 = 0.18, p < 0.001). Thigh and leg MCSA accounted for 79 and 69% of the variance in impulse generated from a maximal vertical jump (p < 0.001), whereas thigh muscle density predicted only 18% of the variance (p < 0.002). In conclusion, we found that pQCT-derived muscle area is more strongly related to strength and neuromuscular performance than muscle density in adult men and women.

The effect of a seven-week exercise program on golf swing performance and musculoskeletal measures:

As most golf exercise studies have shown improved golf performance as a result of two or three sessions per week, the present study investigated the effects of a supervised exercise session performed once a week for seven weeks on golf swing variables and musculoskeletal screening measures. Professional Golfers Association of Australia International Golf Institute student golfers (n = 43) with a mean ± standard deviation handicap of 8.6 ± 8.3 participated in the study. Each golfer performed 10 musculoskeletal tests and a standardised 60-shot golf performance test (TrackMan, Vedbaek, Denmark) on separate days before and after the seven-week program. Significant improvements in a number of musculoskeletal tests (i.e. left leg bridging (6.6%), thoracic extension (62.5%), right thoracic rotation (23.3%), and right (20.8%) and left single leg squat (29.1%)) were observed (all p ≤ 0.024); however, no significant differences were observed for any golf swing variables. Future research investigating different training protocols may help to determine whether the type or frequency of training has the greatest influence on golf swing performance.