The ulnar collateral ligament loading paradox between in-vitro and in-vivo studies on baseball pitching (narrative review).

Ulnar collateral ligament (UCL) weakening or tears occur in 16% of professional baseball pitchers. To prevent players from sustaining a UCL injury, it is important to understand the relationship between the UCL properties and elbow stabilizers with the load on the UCL during pitching. In-vitro studies showed that the ultimate external valgus torque of 34 Nm would rupture the UCL, which is in apparent conflict with the reported peak valgus torques in pitching (40-120 Nm).

Long-term follow-up of conservatively treated midshaft clavicular fractures on functional outcome.

Background: The aim of this study was to examine the long-term effect of shortening after a midshaft clavicular fracture on strength deficiency in the shoulder.

Method: This study included 18 participants (14 males, 4 females) with a conservatively treated midshaft clavicular fracture. Mean age was 52.

Variable and Asymmetric Range of Enslaving: Fingers Can Act Independently over Small Range of Flexion.

The variability in the numerous tasks in which we use our hands is very large. However, independent movement control of individual fingers is limited. To assess the extent of finger independency during full-range finger flexion including all finger joints, we studied enslaving (movement in non-instructed fingers) and range of independent finger movement through the whole finger flexion trajectory in single and multi-finger movement tasks.

Measuring 3D Hand and Finger Kinematics-A Comparison between Inertial Sensing and an Opto-Electronic Marker System.

Objective analysis of hand and finger kinematics is important to increase understanding of hand function and to quantify motor symptoms for clinical diagnosis. The aim of this paper is to compare a new 3D measurement system containing multiple miniature inertial sensors (PowerGlove) with an opto-electronic marker system during specific finger tasks in three healthy subjects. Various finger movements tasks were performed: flexion, fast flexion, tapping, hand open/closing, ab/adduction and circular pointing.

Health-Related Fitness, Motor Coordination, and Physical and Sedentary Activities of Urban and Rural Children in Suriname.

Background: Health-related fitness (HRF) and motor coordination (MC) can be influenced by children's environment and lifestyle behavior. This study evaluates the association between living environment and HRF, MC, and physical and sedentary activities of children in Suriname.

Methods: Tests were performed for HRF (morphological, muscular, and cardiorespiratory component), gross MC (Körperkoordinations Test für Kinder), fine MC (Movement Assessment Battery for Children), and self-reported activities in 79 urban and 77 rural 7-year-old Maroon children.

Is rotating between static and dynamic work beneficial for our fatigue state?

Shoulder disorders comprise a large part of work-related musculoskeletal disorders. Risk factors, such as repetitiveness and monotony, may cause muscle fatigue and be attenuated by task rotation. We investigated rotation between a dynamic box-lifting task and a relatively static pick-and-place task and aimed to determine whether (1) a high rotation frequency leads to less fatigue development than a low rotation frequency, and (2) a self-selected rotation frequency leads to less fatigue development than imposed rotation frequencies.

Low-intensity wheelchair training in inactive people with long-term spinal cord injury: A randomized controlled trial on fitness, wheelchair skill performance and physical activity levels.

Objective: To investigate the effects of low-intensity wheelchair training on wheelchair-specific fitness, wheelchair skill performance and physical activity levels in inactive people with long-term spinal cord injury.

Design: Randomized controlled trial.

Participants: Inactive manual wheelchair users with spinal cord injury for at least 10 years (n = 29), allocated to exercise (n = 14) or no exercise.

Do field position and playing standard influence athlete performance in wheelchair basketball?

Improved understanding of mobility performance in wheelchair basketball is required to increase game performance. The aim of this study was to quantify the wheelchair-athlete activities of players in different field positions and of different playing standard during wheelchair basketball matches. From video analysis, absolute and relative duration and frequency of wheelchair movements and athlete control options were examined in 27 national standard and 29 international standard players during entire wheelchair basketball matches.

Early motor learning changes in upper-limb dynamics and shoulder complex loading during handrim wheelchair propulsion.

Background: To propel in an energy-efficient manner, handrim wheelchair users must learn to control the bimanually applied forces onto the rims, preserving both speed and direction of locomotion. Previous studies have found an increase in mechanical efficiency due to motor learning associated with changes in propulsion technique, but it is unclear in what way the propulsion technique impacts the load on the shoulder complex. The purpose of this study was to evaluate mechanical efficiency, propulsion technique and load on the shoulder complex during the initial stage of motor learning.

Wheelchair-specific fitness of inactive people with long-term spinal cord injury.

Objectives: To describe wheelchair-specific anaerobic work capacity, isometric strength and peak aerobic work capacity of physically inactive people with long-term spinal cord injury using outcomes of tests that are feasible for use in rehabilitation centres, and to determine associations among these fitness components.

Design: Cross-sectional study.

Participants: Manual wheelchair users with spinal cord injury for at least 10 years, who were inactive based on a norm score of a physical activity questionnaire (n = 29; 22 men; 20 with paraplegia; median age 53 years).

Isokinetic strength differences between patients with primary reverse and total shoulder prostheses: muscle strength quantified with a dynamometer.

Background: Range of motion after total shoulder arthroplasty is better than after reverse shoulder arthroplasty, however with similar clinical outcome. It is unclear if this difference can only be found in the different range of motion or also in the force generating capacity.

Questions: (1) are isokinetically produced joint torques of reverse shoulder arthroplasty comparable to those of total shoulder arthroplasty? (2) Does this force-generating capacity correlate with functional outcome?

Methods: Eighteen reverse shoulder arthroplasty patients (71years (SD 9years)) (21 shoulders, follow-up of 21months (SD 10months)) were recruited, 12 total shoulder arthroplasty patients (69years (SD 9years)) (14 shoulders, follow-up of 35months (SD 11months)).

Inter-individual differences in the initial 80 minutes of motor learning of handrim wheelchair propulsion.

Handrim wheelchair propulsion is a cyclic skill that needs to be learned during rehabilitation. Yet it is unclear how inter-individual differences in motor learning impact wheelchair propulsion practice. Therefore we studied how early-identified motor learning styles in novice able-bodied participants impact the outcome of a low-intensity wheelchair-practice intervention.

Can a 15m-overground wheelchair sprint be used to assess wheelchair-specific anaerobic work capacity?

Objective: To evaluate whether outcomes based on stopwatch time and power output (PO) over a 15m-overground wheelchair sprint test can be used to assess wheelchair-specific anaerobic work capacity, by studying their relationship with outcomes on a Wingate-based 30s-wheelchair ergometer sprint (WAnT).

Methods: Able-bodied persons (N=19, 10 men, aged 18-26 y) performed a 15m overground sprint test in an instrumented wheelchair and a WAnT. 15m-outcomes were based on stopwatch time (time and mean velocity over 15m) and on PO (primary outcome: highest mean unilateral PO over successive 5s-intervals (P5-15m)).

Initial Skill Acquisition of Handrim Wheelchair Propulsion: A New Perspective.

To gain insight into cyclic motor learning processes, hand rim wheelchair propulsion is a suitable cyclic task, to be learned during early rehabilitation and novel to almost every individual. To propel in an energy efficient manner, wheelchair users must learn to control bimanually applied forces onto the rims, preserving both speed and direction of locomotion. The purpose of this study was to evaluate mechanical efficiency and propulsion technique during the initial stage of motor learning.

Clinical applications of musculoskeletal modelling for the shoulder and upper limb.

Musculoskeletal models have been developed to estimate internal loading on the human skeleton, which cannot directly be measured in vivo, from external measurements like kinematics and external forces. Such models of the shoulder and upper extremity have been used for a variety of purposes, ranging from understanding basic shoulder biomechanics to assisting in preoperative planning. In this review, we provide an overview of the most commonly used large-scale shoulder and upper extremity models and categorise the applications of these models according to the type of questions their users aimed to answer.

Variability in bimanual wheelchair propulsion: consistency of two instrumented wheels during handrim wheelchair propulsion on a motor driven treadmill.

Background: Handrim wheelchair propulsion is a complex bimanual motor task. The bimanually applied forces on the rims determine the speed and direction of locomotion. Measurements of forces and torques on the handrim are important to study status and change of propulsion technique (and consequently mechanical strain) due to processes of learning, training or the wheelchair configuration.

Effect of workload setting on propulsion technique in handrim wheelchair propulsion.

Objective: To investigate the influence of workload setting (speed at constant power, method to impose power) on the propulsion technique (i.e. force and timing characteristics) in handrim wheelchair propulsion.

Design of a randomized-controlled trial on low-intensity aerobic wheelchair exercise for inactive persons with chronic spinal cord injury.

Purpose: To investigate effects and working mechanisms of low-intensity aerobic wheelchair exercise on fitness, (upper-body) health and active lifestyle in inactive persons with chronic spinal cord injury (SCI).

Methods: A multicenter randomized-controlled trial (RCT) in 40 inactive manual wheelchair users (aged 28-65y) with chronic paraplegia or tetraplegia (time since injury >10y). Subjects will be randomly assigned to an intervention or a control group.

The effect of experimental shortening of the clavicle on shoulder kinematics.

Background: Malunion after mid shaft clavicle fractures has recently been recognized as a cause of pain and dysfunction of the shoulder. The mechanism that causes these complaints is however yet unclear. In this study we describe the kinematic changes that occur in the shoulder girdle due to clavicle shortening.

Kinematic evaluation of patients with total and reverse shoulder arthroplasty during rehabilitation exercises with different loads.

Background: Following shoulder arthroplasty, any well-planned rehabilitation program should include muscle strengthening. However, it is not always clear how different external loads influence shoulder kinematics in patients with shoulder prostheses. The objective of this study was to describe shoulder kinematics and determine the contribution of the scapulothoracic joint to total shoulder motion of patients with total and reverse shoulder arthroplasties and of healthy individuals during rehabilitation exercises (anteflexion and elevation in the scapular plane) using different loading conditions (without external load, 1 kg and elastic resistance).

Shoulder load during synchronous handcycling and handrim wheelchair propulsion in persons with paraplegia.

Objective: To compare the shoulder load during handcycling and wheelchair propulsion under similar conditions of external power in persons with spinal cord injury.

Design: Cross-sectional.

Subjects: Eight men with spinal cord injury.

Shoulder load during handcycling at different incline and speed conditions.

Background: The manual wheelchair user population experiences a high prevalence of upper-limb injuries, which are related to a high load on the shoulder joint during activities of daily living, such as handrim wheelchair propulsion. An alternative mode of propulsion is handcycling, where lower external forces are suggested to be applied to reach the same power output as in handrim wheelchair propulsion. This study aimed to quantify glenohumeral contact forces and muscle forces during handcycling and compare them to previous results of handrim wheelchair propulsion.

Are the force characteristics of synchronous handcycling affected by speed and the method to impose power?

Objective: To investigate the influence of exercise conditions (speed and method to impose power) on the applied force, force effectiveness and distribution of work during handcycling.

Method: Ten able-bodied men performed handcycling on a treadmill. To test the effect of speed, subjects propelled at different velocities (1.