scholarly journals Dynamic Balanced Reach: A Temporal and Spectral Analysis Across Increasing Performance Demands

2016 ◽  
Vol 138 (12) ◽  
Author(s):  
Joseph E. Barton ◽  
Valentina Graci ◽  
Charlene Hafer-Macko ◽  
John D. Sorkin ◽  
Richard F. Macko
Keyword(s):  
Transfer Functions ◽  
Ground Plane ◽  
Reaction Force ◽  
Tracking Error ◽  
Instructional Materials ◽  
Whole Body ◽  
Work Place ◽  
Projection Screen ◽  
Balance Task ◽  
Populations At Risk

Standing balanced reach is a fundamental task involved in many activities of daily living that has not been well analyzed quantitatively to assess and characterize the multisegmental nature of the body's movements. We developed a dynamic balanced reach test (BRT) to analyze performance in this activity; in which a standing subject is required to maintain balance while reaching and pointing to a target disk moving across a large projection screen according to a sum-of-sines function. This tracking and balance task is made progressively more difficult by increasing the disk's overall excursion amplitude. Using kinematic and ground reaction force data from 32 young healthy subjects, we investigated how the motions of the tracking finger and whole-body center of mass (CoM) varied in response to the motion of the disk across five overall disk excursion amplitudes. Group representative performance statistics for the cohort revealed a monotonically increasing root mean squared (RMS) tracking error (RMSE) and RMS deviation (RMSD) between whole-body CoM (projected onto the ground plane) and the center of the base of support (BoS) with increasing amplitude (p < 0.03). Tracking and CoM response delays remained constant, however, at 0.5 s and 1.0 s, respectively. We also performed detailed spectral analyses of group-representative response data for each of the five overall excursion amplitudes. We derived empirical and analytical transfer functions between the motion of the disk and that of the tracking finger and CoM, computed tracking and CoM responses to a step input, and RMSE and RMSD as functions of disk frequency. We found that for frequencies less than 1.0 Hz, RMSE generally decreased, while RMSE normalized to disk motion amplitude generally increased. RMSD, on the other hand, decreased monotonically. These findings quantitatively characterize the amplitude- and frequency-dependent nature of young healthy tracking and balance in this task. The BRT is not subject to floor or ceiling effects, overcoming an important deficiency associated with most research and clinical instruments used to assess balance. This makes a comprehensive quantification of young healthy balance performance possible. The results of such analyses could be used in work space design and in fall-prevention instructional materials, for both the home and work place. Young healthy performance represents “exemplar” performance and can also be used as a reference against which to compare the performance of aging and other clinical populations at risk for falling.

scholarly journals Small changes in ball position at address cause a chain effect in golf swing

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Sung Eun Kim ◽  
Jangyun Lee ◽  
Sae Yong Lee ◽  
Hae-Dong Lee ◽  
Jae Kun Shim ◽  
...  
Keyword(s):  
Ground Reaction Force ◽  
Reaction Force ◽  
Statistical Parametric Mapping ◽  
Golf Swing ◽  
Whole Body ◽  
Centre Of Mass ◽  
Body Segment ◽  
A Chain ◽  
Professional Golfers ◽  
The Right

AbstractThe purpose of this study was to investigate how the ball position along the mediolateral (M-L) direction of a golfer causes a chain effect in the ground reaction force, body segment and joint angles, and whole-body centre of mass during the golf swing. Twenty professional golfers were asked to complete five straight shots for each 5 different ball positions along M-L: 4.27 cm (ball diameter), 2.14 cm (ball radius), 0 cm (reference position at preferred ball position), – 2.14 cm, and – 4.27 cm, while their ground reaction force and body segment motions were captured. The dependant variables were calculated at 14 swing events from address to impact, and the differences between the ball positions were evaluated using Statistical Parametric Mapping. The left-sided ball positions at address showed a greater weight distribution on the left foot with a more open shoulder angle compared to the reference ball position, whereas the trend was reversed for the right-sided ball positions. These trends disappeared during the backswing and reappeared during the downswing. The whole-body centre of mass was also located towards the target for the left-sided ball positions throughout the golf swing compared to the reference ball position, whereas the trend was reversed for the right-sided ball positions. We have concluded that initial ball position at address can cause a series of chain effects throughout the golf swing.

Inter-Subject Variability in Ground Reaction Force - Walking Speed Relationship Is Related to Different Motion of the Center of Mass

2009 ◽  
Author(s):  
Katherine Boyer ◽  
Jonathan Rylander ◽  
Thomas Andriacchi ◽  
Gary Beaupre
Keyword(s):  
Individual Differences ◽  
Bone Mass ◽  
Training Programs ◽  
Center Of Mass ◽  
Reaction Force ◽  
Positive Influence ◽  
Variable Response ◽  
Mineral Density ◽  
Populations At Risk ◽  
Walking Programs

Walking programs provide an attractive intervention to address the preservation of bone mass in the aging population. Research suggests one in three women and one in five men over 50 will experience fractures due to osteoporosis [1,2]. Bone is a mechanically modulated tissue and thus, training programs that prescribe physical activities that dynamically load the skeleton through either muscle contractions (strength training) or locomotion (walking/running) would be expected to have a positive influence on bone mineral density (BMD) preservation. However, attempts to implement activity programs in populations at risk for developing osteoporosis to accrue or simply preserve bone mass have had limited success [3] due to a variable response between subjects. It has been suggested that the failure of these programs to significantly influence bone mass or density may be due to individual differences in the loads generated by the prescribed exercise regimes and/or the knowledge of specific types, intensities and volumes needed for effective osteogenic exercise. Walking, a simple, common activity, presents an interesting opportunity to examine the potential for individual differences in the style of walking to explain the variability in individual results to training programs designed to preserve bone density.

Biomechanics Differ for Individuals With Similar Self-Reported Characteristics of Patellofemoral Pain During a High-Demand Multiplanar Movement Task

2020 ◽  
pp. 1-10
Author(s):  
Matthew K. Seeley ◽  
Seong Jun Son ◽  
Hyunsoo Kim ◽  
J. Ty Hopkins
Keyword(s):  
Ground Reaction Force ◽  
Injury Risk ◽  
Reaction Force ◽  
Patellofemoral Pain ◽  
Joint Torque ◽  
Whole Body ◽  
Ground Contact ◽  
High Demand ◽  
Contact Phase ◽  
Hip Extension

Context: Patellofemoral pain (PFP) is often categorized by researchers and clinicians using subjective self-reported PFP characteristics; however, this practice might mask important differences in movement biomechanics between PFP patients. Objective: To determine whether biomechanical differences exist during a high-demand multiplanar movement task for PFP patients with similar self-reported PFP characteristics but different quadriceps activation levels. Design: Cross-sectional design. Setting: Biomechanics laboratory. Participants: A total of 15 quadriceps deficient and 15 quadriceps functional (QF) PFP patients with similar self-reported PFP characteristics. Intervention: In total, 5 trials of a high-demand multiplanar land, cut, and jump movement task were performed. Main Outcome Measures: Biomechanics were compared at each percentile of the ground contact phase of the movement task (α = .05) between the quadriceps deficient and QF groups. Biomechanical variables included (1) whole-body center of mass, trunk, hip, knee, and ankle kinematics; (2) hip, knee, and ankle kinetics; and (3) ground reaction forces. Results: The QF patients exhibited increased ground reaction force, joint torque, and movement, relative to the quadriceps deficient patients. The QF patients exhibited: (1) up to 90, 60, and 35 N more vertical, posterior, and medial ground reaction force at various times of the ground contact phase; (2) up to 4° more knee flexion during ground contact and up to 4° more plantarflexion and hip extension during the latter parts of ground contact; and (3) up to 26, 21, and 48 N·m more plantarflexion, knee extension, and hip extension torque, respectively, at various times of ground contact. Conclusions: PFP patients with similar self-reported PFP characteristics exhibit different movement biomechanics, and these differences depend upon quadriceps activation levels. These differences are important because movement biomechanics affect injury risk and athletic performance. In addition, these biomechanical differences indicate that different therapeutic interventions may be needed for PFP patients with similar self-reported PFP characteristics.

Comparison of Biomechanical Factors between the Kicking and Stance Limbs

2004 ◽  
Vol 13 (2) ◽  
pp. 135-150 ◽  
Author(s):  
Scott Ross ◽  
Kevin Guskiewicz ◽  
William Prentice ◽  
Robert Schneider ◽  
Bing Yu
Keyword(s):  
Knee Flexion ◽  
Reaction Force ◽  
Knee Extension ◽  
Knee Kinematic ◽  
Vertical Ground Reaction Force ◽  
Time To Peak ◽  
Balance Task ◽  
Vertical Ground ◽  
Biomechanical Factors ◽  
Anterior Posterior

Objective:T o determine differences between contralateral limbs’ strength, proprio-ception, and kinetic and knee-kinematic variables during single-limb landing.Setting:Laboratory.Subjects:30.Measurements:Hip, knee, and foot isokinetic peak torques; anterior/posterior (AP) and medial/lateral (ML) sway displacements during a balance task; and stabilization times, vertical ground-reaction force (VGRF), time to peak VGRF, and knee-flexion range of motion (ROM) from initial foot contact to peak VGRF during single-limb landing.Results:The kicking limb had significantly greater values for knee-extension (P= .008) and -flexion (P= .047) peak torques, AP sway displacement (P= .010), knee-flexion ROM from initial foot contact to peak VGRF (P< .001), and time to peak VGRF (P= .004). No other dependent measures were significantly different between limbs (P> .05).Conclusion:The kicking limb had superior thigh strength, better proprioception, and greater knee-flexion ROM than the stance limb.

Does Delivery Length Impact Measures of Whole-Body Biomechanical Load During Pace Bowling?

2020 ◽  
Vol 15 (10) ◽  
pp. 1485-1489
Author(s):  
Samuel J. Callaghan ◽  
Robert G. Lockie ◽  
Walter Yu ◽  
Warren A. Andrews ◽  
Robert F. Chipchase ◽  
...  
Keyword(s):  
Ground Reaction Force ◽  
Repeated Measures ◽  
Reaction Force ◽  
Practical Importance ◽  
Whole Body ◽  
Loading Rates ◽  
Biomechanical Loading ◽  
Repeated Measures Analysis ◽  
Load Monitoring ◽  
Monitoring Practice

Purpose: To investigate whether changes in delivery length (ie, short, good, and full) lead to alterations in whole-body biomechanical loading as determined by ground reaction force during front-foot contact of the delivery stride for pace bowlers. Current load-monitoring practices of pace bowling in cricket assume equivocal biomechanical loading as only the total number of deliveries are monitored irrespective of delivery length. Methods: A total of 16 male pace bowlers completed a 2-over spell at maximum intensity while targeting different delivery lengths (short, 7–10 m; good, 4–7 m; and full, 0–4 m from the batter’s stumps). In-ground force plates were used to determine discrete (vertical and braking force, impulse, and loading rates) and continuous front-foot contact ground reaction force. Repeated-measures analysis of variance (P < .05), effects size, and statistical parametrical mapping were used to determine differences between delivery lengths. Results: There were no significant differences between short, good, and full delivery lengths for the discrete and continuous kinetic variables investigated (P = .19–1.00), with trivial to small effect sizes. Conclusion: There were minimal differences in front-foot contact biomechanics for deliveries of different lengths (ie, short, good, and full). These data reinforce current pace bowling load-monitoring practices (ie, counting the number of deliveries), as changes in delivery length do not affect the whole-body biomechanical loading experienced by pace bowlers. This is of practical importance as it retains simplicity in load-monitoring practice that is used widely across different competition levels and ages.

scholarly journals The Effectiveness of Physical Exercise on Bone Density in Osteoporotic Patients

2018 ◽  
Vol 2018 ◽  
pp. 1-10 ◽  
Author(s):  
Maria Grazia Benedetti ◽  
Giulia Furlini ◽  
Alessandro Zati ◽  
Giulia Letizia Mauro
Keyword(s):  
Bone Density ◽  
Physical Exercise ◽  
Bone Mass ◽  
Weight Bearing ◽  
Reaction Force ◽  
Whole Body Vibration ◽  
Whole Body ◽  
Body Vibration ◽  
Body Regions ◽  
Resistance Exercises

Physical exercise is considered an effective means to stimulate bone osteogenesis in osteoporotic patients. The authors reviewed the current literature to define the most appropriate features of exercise for increasing bone density in osteoporotic patients. Two types emerged: (1) weight-bearing aerobic exercises, i.e., walking, stair climbing, jogging, and Tai Chi. Walking alone did not appear to improve bone mass; however it is able to limit its progressive loss. In fact, in order for the weight-bearing exercises to be effective, they must reach the mechanical intensity useful to determine an important ground reaction force. (2) Strength and resistance exercises: these are carried out with loading (lifting weights) or without (swimming, cycling). For this type of exercise to be effective a joint reaction force superior to common daily activity with sensitive muscle strengthening must be determined. These exercises appear extremely site-specific, able to increase muscle mass and BMD only in the stimulated body regions. Other suggested protocols are multicomponent exercises and whole body vibration. Multicomponent exercises consist of a combination of different methods (aerobics, strengthening, progressive resistance, balancing, and dancing) aimed at increasing or preserving bone mass. These exercises seem particularly indicated in deteriorating elderly patients, often not able to perform exercises of pure reinforcement. However, for these protocols to be effective they must always contain a proportion of strengthening and resistance exercises. Given the variability of the protocols and outcome measures, the results of these methods are difficult to quantify. Training with whole body vibration (WBV): these exercises are performed with dedicated devices, and while it seems they have effect on enhancing muscle strength, controversial findings on improvement of BMD were reported. WBV seems to provide good results, especially in improving balance and reducing the risk of falling; in this, WBV appears more efficient than simply walking. Nevertheless, contraindications typical of senility should be taken into account.

EVALUATION OF A COMPUTER-SIMULATION MODEL FOR HUMAN AMBULATION ON STILTS

2004 ◽  
Vol 04 (03) ◽  
pp. 283-303 ◽  
Author(s):  
CHRISTOPHER S. PAN ◽  
KIMBERLY M. MILLER ◽  
SHARON CHIOU ◽  
JOHN Z. WU
Keyword(s):  
Computer Simulation ◽  
Ground Reaction Force ◽  
Center Of Mass ◽  
Reaction Force ◽  
Construction Workers ◽  
Whole Body ◽  
Vertical Ground Reaction Force ◽  
Actual Measurement ◽  
Increased Risk ◽  
Vertical Ground

Stilts are elevated tools that are frequently used by construction workers to raise workers 18 to 40 inches above the ground without the burden of erecting scaffolding or a ladder. Some previous studies indicated that construction workers perceive an increased risk of injury when working on stilts. However, no in-depth biomechanical analyses have been conducted to examine the fall risks associated with the use of stilts. The objective of this study is to evaluate a computer-simulation stilts model. Three construction workers were recruited for walking tasks on 24-inch stilts. The model was evaluated using whole body center of mass and ground reaction forces. A PEAK™ motion system and two Kistler™ force platforms were used to collect data on both kinetic and kinematic measures. Inverse- and direct-dynamics simulations were performed using a model developed using commercial software — ADAMS and LifeMOD. For three coordinates (X, Y, Z) of the center of mass, the results of univariate analyses indicated very small variability for the mean difference between the model predictions and the experimental measurements. The results of correlation analyses indicated similar trends for the three coordinates. Plotting the resultant and vertical ground reaction force for both right and left feet showed small discrepancies, but the overall shape was identical. The percentage differences between the model and the actual measurement for three coordinates of the center of mass, as well as resultant and vertical ground reaction force, were within 20%. This newly-developed stilt walking model may be used to assist in improving the design of stilts.

Sign in / Sign up

Export Citation Format

Share Document