LANDING ASYMMETRY IN BACK TUCKED SALTOS AND THE EFFECT OF TAKEOFF ASYMMETRY

Landing asymmetry is an injury risk factor in gymnastics. This study examined whether takeoff force asymmetry is related to landing asymmetry during back tucked saltos in competitive gymnasts. Each gymnast performed an isometric leg strength test followed by multiple back tucked salto trials with no takeoff instruction, leaning with 60% asymmetry to the right, and 60% asymmetry to the left using a standard asymmetry index. Forces were measured at takeoff and landing. The novel experimental approach successfully produced distinct takeoff asymmetry levels. There was a significant rightward asymmetry in baseline landing peak vertical force, possibly due to right leg strength dominance. Landing asymmetry was also generated in the left and right leaning conditions. Both takeoff and leg strength asymmetries may play a role in landing force asymmetries in back tucked saltos

Age differences in upper extremity joint moments and strength during a laboratory-based tether-release forward fall arrest in older women

Age-related declines in upper extremity muscle strength may affect an older adult’s ability to land and control a simulated forward fall impact. The role of individual upper extremity joints during a forward fall impact has not been examined. The purpose was to evaluate the age differences in upper extremity joint moment contributions during a simulated forward fall and upper extremity muscle strength in older women. A convenience sample of 68 older women (70 (8) yrs) performed three trials of a simulated forward fall. Percentage joint moments of the upper extremity were recorded. Upper extremity muscle strength was collected via handgrip, hand-held dynamometry of the shoulder and elbow and a custom multi-joint concentric and eccentric strength isokinetic dynamometer protocol. Percentage joint moment contributions differed between women in their sixties and seventies with significantly greater relative shoulder joint involvement (P = .008), coupled with lower elbow joint contributions (P = .004) in comparison to 80 year olds. An increase in each year of age was associated with a 4% increase in elbow contribution (Beta = -0.421, r2 = 17.9, P = 0.0001) and a 3.7% decrease in shoulder contribution (Beta = 0.373, r2 = 14.6, P = 0.002). Older women exhibit different landing strategies as they age. Fall injury prevention research should consider interventions focused on these differences taking into account the contributions of upper extremity strength

The measurement properties of the Lean-and-Release test in people with incomplete spinal cord injury or disease

Objective: To evaluate test-retest reliability, agreement, and convergent validity of the Lean-and-Release test for the assessment of reactive stepping among individuals with incomplete spinal cord injury or disease (iSCI/D). Design: Multi-center cross-sectional multiple test design. Setting: SCI/D rehabilitation hospital and biomechanics laboratory. Participants: Individuals with motor incomplete SCI/D (iSCI/D). Interventions: None. Outcome Measures: Twenty-six participants attended two sessions to complete the Lean-and-Release test and a battery of clinical tests. Behavioral (i.e. one-step, multi-step, loss of balance) and temporal (i.e. timing of foot off, foot contact, swing of reactive step) parameters were measured. Test-retest reliability was determined with intraclass correlation coefficients, and agreement was evaluated with Bland–Altman plots. Convergent validity was assessed through correlations with clinical tests. Results: The behavioral responses were reliable for the Lean-and-Release test (ICC = 0.76), but foot contact was the only reliable temporal parameter using data from a single site (ICC = 0.79). All variables showed agreement according to the Bland–Altman plots. The behavioral responses correlated with scores of lower extremity strength (0.54, P\u3c0.01) and balance confidence (0.55, P \u3c 0.01). Swing time of reactive stepping correlated with step time (0.73, P \u3c 0.01) and cadence (−0.73 P \u3c 0.01) of over ground walking. Conclusions: The behavioral response of the Lean-and-Release test is a reliable and valid measure for people with iSCI/D. Our findings support the use of the behavioral responses to evaluate reactive stepping for research and clinical purposes. Trial registration: ClinicalTrials.gov identifier: NCT02960178

The effect of acute equine temporomandibular joint inflammation on response to rein-tension and kinematics

BackgroundAlthough the temporomandibular joint (TMJ) is the major contact point between the reins in the riders’ hand, the bit in the mouth, and the rest of the horse under saddle, the role of inflammation of this joint on equine locomotion and rein tension is unknown.ObjectiveTo determine the effect of acute TMJ inflammation on rein-tension and horse movement when horses were long-reined on a treadmill.Study designA randomized, controlled, cross-over design.MethodsFive horses were trained by one clinician to walk and trot on a treadmill wearing long-reining equipment instrumented with a rein-tension device and reflective optical tracking markers. Subjective assessment of horse’s dominant side, and movement, were determined without rein-tension (free walk and trot); and with rein-tension (long-reined walk and trot). Continuous rein-force data from both sides were collected over ~60s from each trial. Movement was recorded using a 12-camera optical motion capture system. One randomly assigned TMJ was subsequently injected with lipopolysaccharide and the treadmill tests repeated by investigators blinded to treatment side. A second, identical assessment was performed 10 days later with the opposite TMJ being the target of intervention.ResultsAll horses showed reduced rein-tension on the injected (inflamed) side. Increased rein-tension was required on the non-injected side at trot, to maintain them in the correct position on the treadmill post-injection. The only kinematic variable to show any significant change due to rein tension or TMJ inflammation during the walk or trot was an increase in forward head tilt in the presence of rein tension in the trot after injection.Main limitationsLow number of horses and investigation of response to acute inflammation only.ConclusionTMJ inflammation changed, subjectively and objectively, the response to rein-input, but the horses did not become lame

The reliability and validity of novel clinical strength measures of the upper body in older adults.

Introduction: Research investigating psychometric properties of multi-joint upper body strength assessment tools for older adults is limited. This study aimed to assess the test-retest reliability and concurrent validity of novel clinical strength measures assessing functional concentric and eccentric pushing activities compared to other more traditional upper limb strength measures. Methods: Seventeen participants (6 males and 11 females; 71 ± 10 yrs) were tested 2 days apart, performing three maximal repetitions of the novel measurements: vertical push-off test and dynamometer-controlled concentric and eccentric single-arm press. Three maximal repetitions of hand-grip dynamometry and isometric hand-held dynamometry for shoulder flexion, shoulder abduction and elbow extension were also collected. Results: For all measures, strong test-retest reliability was shown (all ICC > 0.90, p 0.8, p < 0.001). Discussion: The push off test and dynamometer-controlled concentric and eccentric single-arm press are reliable and valid strength measures feasible for testing multi-joint functional UE strength assessment in older adults. Higher precision error compared to traditional uni-planar measures warrants caution when completing comparative clinical assessments over time

Fall arrest strategy training improves upper body response time compared to standard fall prevention exercise in older women: A randomized trial

Introduction: Exercise can decrease fall risk in older adults but less is known about training to reduce injury risk in the event a fall is unavoidable. The purpose of this study was to compare standard fall prevention exercises to novel Fall Arrest Strategy Training (FAST); exercises designed to improve upper body capacity to reduce fall-injury risk in older women. Method: Forty women (mean age 74.5 years) participated in either Standard (n=19) or FAST (n=21) twice per week for 12 weeks. Both interventions included lower body strength, balance, walking practice, agility and education. FAST added exercises designed to enhance forward landing and descent control such as upper body strengthening, speed and practice of landing and descent on outstretched hands. Results: Both FAST and Standard significantly improved strength, mobility, balance, and fall risk factors from pre to post-intervention. There was a significant time by group interaction effect for upper body response time where FAST improved but Standard did not (p = .038). Discussion: FAST resulted in similar gains in factors that reduce fall risk as a standard fall prevention program; with the additional benefit of improving speed of arm protective responses; a factor that may help enhance landing position and reduce injury risks such as head impact during a forward fall

Does functional performance and upper body strength predict upper extremity reaction and movement time in older women?

Background: Reaction time to initiate upper limb movement and movement time to place hands on the landing surface may be important factors in forward fall landing and impact, contributing to injury reduction. The aim was to investigate the relationship of physical function and upper body strength to upper limb reaction and movement time in older female participants. Methods: 75 female participants (72 ± 8 yrs) performed 5 arm response trials. Reaction time (signal to initiation of movement), and movement time (initial movement to contact), were collected using 3D motion capture. Additional variables were: handgrip; sit-to-stand; shoulder flexion and elbow extension strength measured by hand-held dynamometry; one-legged balance; fall risk; and physical activity scores. Prediction variables for reaction and movement time were determined in separate backward selection multiple regression analyses. Significance was set at P<0.05. Findings: Significant regression equations for RT (r2 = .08, P = 0.013) found a relationship between stronger handgrip (Beta = -.002) and faster reaction time, accounting for 8% variance. For movement time (r2 = .06, P= .036) greater shoulder flexion strength (Beta = -.04) was related to faster movement time, explaining 6% variance. Stronger SF strength was related to a decrease in MT by 4%. Discussion: A relationship between arm strength measures and faster upper body reaction and movement time was shown, with 10-20% higher strength associated with a 5% faster response time. Even though this was a relatively weak relationship, given that strength is a modifiable component this provides a potential avenue for future intervention efforts. This in turn could have an impact on forward fall landing and potential reduction of injury risk

Preliminary study of novel, timed walking tests for children with spina bifida or cerebral palsy

Objective: Walking assessment is an important aspect of rehabilitation practice; yet, clinicians have few psychometrically sound options for evaluating walking in highly ambulatory children. The purpose of this study was to evaluate the validity and reliability of two new measures of walking function—the Obstacles and Curb tests—relative to the 10-Meter Walk test and Timed Up and Go test in children with spina bifida or cerebral palsy. Methods: A total of 16 ambulatory children with spina bifida ( n =9) or cerebral palsy ( n =7) (9 boys; mean age 7years, 7months; standard deviation 3years, 4months) and 16 age- and gender-matched typically developing children participated. Children completed the walking tests, at both self-selected and fast speeds, twice. To evaluate discriminative validity, scores were compared between typically developing and spina bifida/cerebral palsy groups. Within the spina bifida/cerebral palsy group, inter-test correlations evaluated convergent validity and intraclass correlation coefficients evaluated within-session test–retest reliability. Results: At fast speeds, all tests showed discriminative validity ( p <0.006 for typically developing and spina bifida/cerebral palsy comparisons) and convergent validity ( rho =0.81–0.90, p ⩽0.001, for inter-test correlations). At self-selected speeds, only the Obstacles test discriminated between groups ( p =0.001). Moderately strong correlations ( rho =0.73–0.78, p ⩽0.001) were seen between the 10-Meter Walk test, Curb test, and Timed Up and Go test. Intraclass correlation coefficients ranged from 0.81 to 0.97, with higher test–retest reliability for tests performed at fast speeds rather than self-selected speeds. Conclusion: The Obstacles and Curb tests are promising measures for assessing walking in this population. Performing tests at fast walking speeds may improve their validity and test–retest reliability for children with spina bifida/cerebral palsy