Antagonism of 5-HT2 receptors attenuates self-sustained firing of human motor units

5-HT2 receptors on motoneurones play a critical role in facilitating persistent inward currents (PICs). Although facilitation of PICs can enhance self-sustained firing after periods of excitation, the relationship between 5-HT2 receptor activity and self-sustained firing in human motor units (MUs) has not been resolved. MU activity was assessed from the tibialis anterior of 10 healthy adults (24.9 ± 2.8 years) during two contraction protocols. Both protocols featured steady-state isometric contractions with constant descending drive to the motoneurone pool. However, one protocol also included an additional phase of superimposed descending drive. Adding and then removing descending drive in the middle of steady-state contractions altered MU firing behaviour across the motor pool, where newly recruited units in the superimposed phase were unable to switch off (P = 0.0002), and units recruited prior to additional descending drive reduced their discharge rates (P < 0.0001, difference in estimated marginal means (∆) = 2.24 pulses/s). The 5-HT2 receptor antagonist, cyproheptadine, was then administered to determine whether changes in MU firing were mediated by serotonergic mechanisms. 5-HT2 receptor antagonism caused reductions in MU discharge rate (P < 0.001, ∆ = 1.65 pulses/s), recruitment threshold (P = 0.00112, ∆ = 1.09% maximal voluntary contraction) and self-sustained firing duration (P < 0.0001, ∆ = 1.77s) after the additional descending drive was removed in the middle of the steady-state contraction. These findings indicate that serotonergic neuromodulation plays a key role in facilitating discharge and self-sustained firing of human motoneurones, where adaptive changes in MU recruitment must occur to meet the demands of the contraction. KEY POINTS: Animal and cellular preparations indicate that somato-dendritic 5-HT2 receptors regulate the intrinsic excitability of motoneurones. 5-HT2 receptor antagonism reduces estimates of persistent inward currents in motoneurones, which contribute to self-sustained firing when synaptic inputs are reduced or removed. This human study employed a contraction task that slowly increased (and then removed) the additional descending drive in the middle of a steady-state contraction where marked self-sustained firing occurred when the descending drive was removed. 5-HT2 receptor antagonism caused widespread reductions in motor unit (MU) discharge rates during contractions, which was accompanied by reduced recruitment threshold and attenuation of self-sustained firing duration after the removal of the additional descending drive to motoneurones. These findings support the role that serotonergic neuromodulation is a key facilitator of MU discharge and self-sustained firing of human motoneurones, where adaptative changes in MU recruitment must occur to meet the demands of the contraction.

Blockade of 5-HT2 receptors suppresses motor unit firing and estimates of persistent inward currents during voluntary muscle contraction in humans

Serotonergic neuromodulation contributes to enhanced voluntary muscle activation. However, it is not known how the likely motoneurone receptor candidate (5-HT₂ ) influences the firing rate and activation threshold of motor units (MUs) in humans. The purpose of this study was to determine whether 5-HT₂ receptor activity contributes to human MU behaviour during voluntary ramped contractions of differing intensity. High-density surface EMG (HDsEMG) of the tibialis anterior was assessed during ramped isometric dorsiflexions at 10, 30, 50 and 70% of maximal voluntary contraction (MVC). MU characteristics were successfully extracted from HDsEMG of 11 young adults (four female) pre- and post-ingestion of 8 mg cyproheptadine or a placebo. Antagonism of 5-HT₂ receptors caused a reduction in MU discharge rate during steady-state muscle activation that was independent of the level of contraction intensity [P < 0.001; estimated mean difference (∆) = 1.06 pulses/s], in addition to an increase in MU derecruitment threshold (P < 0.013, ∆ = 1.23% MVC), without a change in force during MVC (P = 0.652). A reduction in estimates of persistent inward current amplitude was observed at 10% MVC (P < 0.001, ∆ = 0.99 Hz) and 30% MVC (P = 0.003, ∆ = 0.75 Hz) that aligned with 5-HT changes in MU firing behaviour attributable to 5-HT₂ antagonism. Overall, these findings indicate that 5-HT₂ receptor activity has a role in regulating the discharge rate in populations of spinal motoneurones when performing voluntary contractions. This study provides evidence of a direct link between MU discharge properties, persistent inward current activity and 5-HT₂ receptor activity in humans. KEY POINTS: Activation of 5-HT receptors on the soma and dendrites of motoneurones regulates their excitability. Previous work using chlorpromazine and cyproheptadine has demonstrated that the 5-HT₂ receptor regulates motoneurone activity in humans with chronic spinal cord injury and non-injured control subjects. It is not known how the 5-HT₂ receptor directly influences motor unit (MU) discharge and MU recruitment in larger populations of human motoneurones during voluntary contractions of differing intensity. Despite the absence of change in force during maximal voluntary dorsiflexions, 5-HT₂ receptor antagonism caused a reduction in MU discharge rate during submaximal steady-state muscle contraction, in addition to an increase in MU derecruitment threshold, irrespective of the submaximal contraction intensity. Reductions in estimates of persistent inward currents after 5-HT₂ receptor antagonism support the viewpoint that the 5-HT₂ receptor plays a crucial role in regulating motor activity, whereby a persistent inward current-based mechanism is involved in regulating the excitability of human motoneurones.

Blockade of 5-HT2 receptors suppresses rate of torque development and motor unit discharge rate during rapid contractions

Serotonin (5-HT) is a neuromodulator that is critical for regulating the excitability of spinal motoneurons and the generation of muscle torque. However, the role of 5-HT in modulating human motor unit activity during rapid contractions has yet to be assessed. Nine healthy participants (23.7 ± 2.2 yr) ingested 8 mg of the competitive 5-HT₂ antagonist cyproheptadine in a double-blinded, placebo-controlled, repeated-measures experiment. Rapid dorsiflexion contractions were performed at 30%, 50% and 70% of maximal voluntary contraction (MVC), where motor unit activity was assessed by high-density surface electromyographic decomposition. A second protocol was performed where a sustained, fatigue-inducing dorsiflexion contraction was completed prior to undertaking the same 30%, 50% and 70% MVC rapid contractions and motor unit analysis. Motor unit discharge rate (p < 0.001) and rate of torque development (RTD; p = 0.019) for the unfatigued muscle were both significantly lower for the cyproheptadine condition. Following the fatigue inducing contraction, cyproheptadine reduced motor unit discharge rate (p < 0.001) and RTD (p = 0.024), where the effects of cyproheptadine on motor unit discharge rate and RTD increased with increasing contraction intensity. Overall, these results support the viewpoint that serotonergic effects in the central nervous system occur fast enough to regulate motor unit discharge rate during rapid powerful contractions.

Lower limb kinematics of single-leg squat performance in patients with anterior cruciate ligament deficiency

[Purpose] This study investigated the parameters that characterize the knee, hip, and pelvic kinematics during a single-leg squat in preoperative anterior cruciate ligament rupture injury. [Participants and Methods] Overall, 15 patients with unilateral anterior cruciate ligament deficiency were enrolled in this study. For each single-leg squat, data from two-dimensional video cameras and three-dimensional motion analysis were collected. Measurement indices included the articular angles of the knee, hip, and trunk. The anterior cruciate ligament-injured leg was compared with the uninjured leg. [Results] The maximum knee valgus and flexion angles during a single-leg squat were smaller in the injured leg than in the uninjured leg. During the single-leg squat, the effect of "compensatory mechanisms" appeared as knee valgus and flexion movements. In particular, the knee valgus angle decreased in the anterior cruciate ligament-injured leg compared to that in the uninjured leg. [Conclusion] This phenomenon suggests that it is possible to utilize recurrence prevention training for anterior cruciate ligament injury.

Functional electrical stimulation cycling, goal-directed training, and adapted cycling for children with cerebral palsy: a randomized controlled trial

AIM

To test the efficacy of functional electrical stimulation (FES) cycling, goal-directed training, and adapted cycling, compared with usual care, to improve function in children with cerebral palsy (CP).

METHOD

The intervention was delivered between 2017 and 2019 and included three sessions per week for 8 weeks (2×1h sessions at a children's hospital, and 1h home programme/week). Hospital sessions included 30 minutes of FES cycling and 30 minutes of goal-directed training. Home programmes included goal-directed training and adapted cycling. The comparison group continued usual care. Primary outcomes were gross motor function assessed by the Gross Motor Function Measure (GMFM) and goal performance/satisfaction assessed using the Canadian Occupational Performance Measure (COPM). Secondary outcomes were sit-to-stand and activity capacity, participation in home, school, and community activities, and power output. Linear regression was used to determine the between-group mean difference immediately post-training completion after adjusting for baseline scores.

RESULTS

This randomized controlled trial included 21 participants (mean age=10y 3mo, standard deviation [SD]=3y; Gross Motor Function Classification System level: II=7, III=6, IV=8) who were randomized to the intervention (n=11) or usual care group (n=10). Between-group differences at T2 favoured the intervention group for GMFM-88 (mean difference=7.4; 95% confidence interval [CI]: 2.3-12.6; p=0.007), GMFM-66 (mean difference=5.9; 95% CI: 3.1-8.8; p<0.001), COPM performance (mean difference=4.4; 95% CI: 3.9-5.3; p<0.001) and satisfaction (mean difference=5.2; 95% CI: 4.0-6.4; p<0.001).

INTERPRETATION

Children with CP achieved meaningful functional improvements after FES cycling, goal-directed training, and adapted cycling training. Cycling programmes for children with CP should be individualized and goal directed.

A qualitative analysis of the experiences of children with cerebral palsy and their caregivers in a goal-directed cycling programme

PURPOSE

This qualitative thematic analysis aimed to capture the experiences of children with cerebral palsy (CP) and caregivers who completed an 8-week goal-directed cycling programme, to provide insights on engagement and programme feasibility.

METHODS

Children with CP (6-18 years, Gross Motor Function Classification Scale (GMFCS) levels II-IV) and caregivers completed semi-structured interviews at the end of the training programme. Interview transcripts were coded by two investigators and systematically organised into themes. A third investigator reviewed the final thematic map.

RESULTS

17 interviews were conducted with 29 participants (11 children: 7-14 years). Four themes emerged: facilitators and challenges to programme engagement; perceived outcomes; the functional-electrical stimulation (FES) cycling experience; and previous cycling participation. Engagement was facilitated by the "therapist's connection," "cycling is fun" and "participant driven goal setting," while "getting there" and "time off school" were identified as challenges. Participants positively linked improved physical function to greater independence. The FES-experience was "fun and challenging," and participants had mixed feelings about electrode "stickiness." Previous cycling participation was limited by access to adapted bikes.

CONCLUSIONS

Children with CP enjoy riding bikes. Facilitators and challenges to engagement were identified that hold practical relevance for clinicians. Environmental and personal factors should be carefully considered when developing future programs, to maximise opportunities for success.

CLINICAL TRIAL REGISTRATION NUMBER

Australian New Zealand Clinical Trials Registry - ACTRN12617000644369pIMPLICATIONS FOR REHABILITATIONAdapted cycling is a fun and engaging activity for young people with cerebral palsy.Environmental and personal factors should be carefully considered when prescribing adapted or FES cycling programs to this group.Engagement in adapted and FES-cycling programs can be facilitated by access to loan equipment, a goal-directed focus, and positive therapist-child relationship.Participation in adapted cycling is limited by access to adapted cycling equipment.

Machine learning to quantify habitual physical activity in children with cerebral palsy

AIM

To investigate whether activity-monitors and machine learning models could provide accurate information about physical activity performed by children and adolescents with cerebral palsy (CP) who use mobility aids for ambulation.

METHOD

Eleven participants (mean age 11y [SD 3y]; six females, five males) classified in Gross Motor Function Classification System (GMFCS) levels III and IV, completed six physical activity trials wearing a tri-axial accelerometer on the wrist, hip, and thigh. Trials included supine rest, upper-limb task, walking, wheelchair propulsion, and cycling. Three supervised learning algorithms (decision tree, support vector machine [SVM], random forest) were trained on features in the raw-acceleration signal. Model-performance was evaluated using leave-one-subject-out cross-validation accuracy.

RESULTS

Cross-validation accuracy for the single-placement models ranged from 59% to 79%, with the best performance achieved by the random forest wrist model (79%). Combining features from two or more accelerometer placements significantly improved classification accuracy. The random forest wrist and hip model achieved an overall accuracy of 92%, while the SVM wrist, hip, and thigh model achieved an overall accuracy of 90%.

INTERPRETATION

Models trained on features in the raw-acceleration signal may provide accurate recognition of clinically relevant physical activity behaviours in children and adolescents with CP who use mobility aids for ambulation in a controlled setting.

WHAT THIS PAPER ADDS

Machine learning may assist clinicians in evaluating the efficacy of surgical and therapy-based interventions. Machine learning may help researchers better understand the short- and long-term benefits of physical activity for children with more severe motor impairments.

The effect of replacing 1 week of content teaching with an intensive simulation-based learning activity on physiotherapy student clinical placement performance

BACKGROUND

Simulation-based learning (SBL) activities are increasingly used to replace or supplement clinical placements for physiotherapy students. There is limited literature evaluating SBL activities that replace on-campus teaching, and to our knowledge, no studies evaluate the role of SBL in counteracting the negative impact of delay between content teaching and clinical placements. The aims of this study were to (i) determine the effect on clinical placement performance of replacing 1 week of content teaching with a SBL activity and (ii) determine if a delay between content teaching and clinical placement impacted clinical placement performance.

METHODS

This study is a retrospective cohort study. Participants included students in the first two clinical placements of a graduate-entry, masters-level program. Six hundred twenty-nine student placements were analysed-285 clinical placements where students undertook a 20-h SBL activity immediately prior to clinical placement were compared with 344 placements where students received traditional content. Of the placements where students received the SBL, 147 occurred immediately following content teaching and 138 had a delay of at least 5 weeks. Performance on clinical placement was assessed using the Assessment of Physiotherapy Practice (APP).

RESULTS

There was a significant main effect of SBL with higher APP marks for the experimental group (3.12/4, SD = 0.25 vs 3.01/4, SD = 0.22), and post hoc analysis indicated marks were significantly higher for all seven areas of assessment. Students whose placements immediately followed content teaching performed better on mid-placement APP marks in two areas of assessment (analysis and planning, and intervention) compared to students for whom there was a delay. There were no statistically significant differences in relation to delay for end of placement APP marks.

CONCLUSION

Replacing 1 week of classroom teaching with a targeted, SBL activity immediately before placement significantly improved student performance on that clinical placement. A negative impact of delay was found on mid-placement, but not the end of placement APPs. Findings of improved performance when replacing a week of content teaching with a targeted SBL activity, and poorer performance on mid-placement marks with a delay between content teaching and clinical placement, may have implications for curriculum design.

Effects of a training programme of functional electrical stimulation (FES) powered cycling, recreational cycling and goal-directed exercise training on children with cerebral palsy: a randomised controlled trial protocol

INTRODUCTION

Children with cerebral palsy (CP) experience declines in gross motor ability as they transition from childhood to adolescence, which can result in the loss of ability to perform sit-to-stand transfers, ambulate or participate in leisure activities such as cycling. Functional electrical stimulation (FES) cycling is a novel technology that may provide opportunities for children with CP to strengthen their lower limbs, improve functional independence and increase physical activity participation. The proposed randomised controlled trial will test the efficacy of a training package of FES cycling, adapted cycling and goal-directed functional training to usual care in children with CP who are susceptible to functional declines.

METHODS AND ANALYSIS

Forty children with CP (20 per group), aged 6-8 years and classified as Gross Motor Function Classification System (GMFCS) levels II-IV will be recruited across South East Queensland. Participants will be randomised to either an immediate intervention group, who will undertake 8 weeks of training, or a waitlist control group. The training group will attend two 1 hour sessions per week with a physiotherapist, consisting of FES cycling and goal-directed, functional exercises and a 1 hour home exercise programme per week, consisting of recreational cycling. Primary outcomes will be the gross motor function measure and Canadian occupational performance measure, and secondary outcomes will include the five times sit-to-stand test, habitual physical activity (accelerometry), power output during cycling and Participation and Environment Measure-Children and Youth. Outcomes will be assessed at baseline, postintervention (8 weeks) and 8 weeks following the intervention (retention).

ETHICS AND DISSEMINATION

Ethical approval has been obtained from Griffith University (2018/037) and the Children's Health Queensland Hospital and Health Service (CHQHHS) Human Research Ethics Committee (HREC/17/QRCH/88). Site-specific approval was obtained from CHQHHS research governance (SSA/17/QRCH/145). Results from this trial will be disseminated via publication in relevant peer-reviewed journals.

TRIAL REGISTRATION NUMBER

ACTRN12617000644369p.

High-intensity exercise did not cause vertebral fractures and improves thoracic kyphosis in postmenopausal women with low to very low bone mass: the LIFTMOR trial

Our aim was to assess risk of vertebral fracture during high-intensity resistance and impact training (HiRIT) for postmenopausal women with low bone mass. HiRIT did not induce vertebral fracture, as evidenced by a reduction in kyphosis following 8 months of training and a lack of change in vertebral morphology.

INTRODUCTION

The LIFTMOR trial demonstrated a novel, HiRIT program notably improved bone mass in postmenopausal women with osteopenia and osteoporosis. While no clinical signs or symptoms of vertebral crush fracture were evident during the trial, anecdotal feedback suggests that concerns about safety of HiRIT in the osteoporosis demographic remain. The aim of the current work was to assess vertebral body morphology, Cobb angle, and clinical measures of thoracic kyphosis in participants in the LIFTMOR trial for evidence of vertebral fracture following 8 months of supervised HiRIT.

METHODS

Participants were randomized to either 8 months of 30-min, twice-weekly, supervised HiRIT or unsupervised, low-intensity, home-based exercise (CON). Lateral thoracolumbar DXA scans (Medix DR, Medilink, France) were performed at baseline and follow-up. Cobb angle was determined, and vertebral fracture identification was performed using the semiquantitative Genant method. Clinical kyphosis measurements were performed in relaxed standing (neutral posture) and standing tall using an inclinometer and a flexicurve.

RESULTS

The HiRIT group exhibited a reduction in inclinometer-determined standing tall thoracic kyphosis compared to CON (- 6.7 ± 8.2° vs - 1.6 ± 8.1°, p = 0.031). Both the HiRIT and CON groups exhibited within-group improvement in kyphosis in relaxed standing as measured by both inclinometer and flexicurve (p < 0.05). There were no changes in vertebral fracture classification in the HiRIT group post-intervention. A single, new, wedge deformity was observed for CON.

CONCLUSIONS

Supervised HiRIT was not associated with an increased risk of vertebral fracture in postmenopausal women with low bone mass. Indeed, a clinically relevant improvement in thoracic kyphosis was observed following 8 months of supervised HiRIT, further supporting its efficacy as an osteoporosis intervention for postmenopausal women with low to very low bone mass.

An examination of treadmill running familiarisation in barefoot and shod conditions in healthy men

Running on a treadmill is an activity that is novel to many people. Thus, a familiarisation period may be required before reliable and valid determinations of biomechanical parameters can be made. The current study investigated the time required for treadmill familiarisation under barefoot and shod running conditions. Twenty-six healthy men, who were inexperienced in treadmill running, were randomly allocated to run barefoot or shod for 20 minutes on a treadmill at a self-selected comfortable pace. Sagittal-plane kinematics for the ankle, knee and hip, and ground reaction force and spatio-temporal data were collected at two-minute intervals. For the barefoot condition, temporal differences were observed in peak hip flexion and peak knee flexion during swing. For the shod condition, temporal differences were observed for peak vertical ground reaction force. No temporal differences were observed after 8 minutes for either condition. Reliability analysis revealed high levels of consistency (ICC > 0.90) across all consecutive time-points for all dependent variables for both conditions after 8 minutes with the exception of maximal initial vertical ground reaction force loading rate. Participants in both barefoot and shod groups were therefore considered familiarised to treadmill running after 8 minutes.

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. © 2017 American Society for Bone and Mineral Research.

Validity and test-retest reliability of a novel simple back extensor muscle strength test

OBJECTIVES

To develop and determine convergent validity and reliability of a simple and inexpensive clinical test to quantify back extensor muscle strength.

METHODS

Two testing sessions were conducted, 7 days apart. Each session involved three trials of standing maximal isometric back extensor muscle strength using both the novel test and isokinetic dynamometry. Lumbar spine bone mineral density was examined by dual-energy X-ray absorptiometry. Validation was examined with Pearson correlations (r). Test-retest reliability was examined with intraclass correlation coefficients and limits of agreement. Pearson correlations and intraclass correlation coefficients are presented with corresponding 95% confidence intervals. Linear regression was used to examine the ability of peak back extensor muscle strength to predict indices of lumbar spine bone mineral density and strength.

RESULTS

A total of 52 healthy adults (26 men, 26 women) aged 46.4 ± 20.4 years were recruited from the community. A strong positive relationship was observed between peak back extensor strength from hand-held and isokinetic dynamometry (r = 0.824, p < 0.001). For the novel back extensor strength test, short- and long-term reliability was excellent (intraclass correlation coefficient = 0.983 (95% confidence interval, 0.971-0.990), p < 0.001 and intraclass correlation coefficient = 0.901 (95% confidence interval, 0.833-0.943), p < 0.001, respectively). Limits of agreement for short-term repeated back extensor strength measures with the novel back extensor strength protocol were -6.63 to 7.70 kg, with a mean bias of +0.71 kg. Back extensor strength predicted 11% of variance in lumbar spine bone mineral density (p < 0.05) and 9% of lumbar spine index of bone structural strength (p < 0.05).

CONCLUSION

Our novel hand-held dynamometer method to determine back extensor muscle strength is quick, relatively inexpensive, and reliable; demonstrates initial convergent validity in a healthy population; and is associated with bone mass at a clinically important site.

Heavy resistance training is safe and improves bone, function, and stature in postmenopausal women with low to very low bone mass: novel early findings from the LIFTMOR trial

The aim of the LIFTMOR (Lifting Intervention For Training Muscle and Osteoporosis Rehabilitation) trial is to determine the safety and efficacy of brief, bone-targeted, high-intensity progressive resistance training (HiPRT) with impact loading for postmenopausal women with low bone mass. Preliminary findings indicate the LIFTMOR program is safe and effective.

INTRODUCTION

Despite a lack of notable efficacy, exercise guidelines for osteoporosis typically recommend moderate-intensity exercises, owing to a perceived risk of fracture from high-intensity loading. Indeed, safety concerns alone have prevented the well-recognised preferential response of bone tissue to high-intensity loads from being applied to those who stand to benefit the most. To progress from this therapeutic stalemate, a challenge to conventional wisdom was required. Our goal was to examine the safety and efficacy of HiPRT and impact loading for risk factors of osteoporotic fracture in postmenopausal women with low to very low bone mass.

METHODS

Participants have been randomised to either 8 months of twice-weekly 30-min supervised HiPRT and impact loading or a low-intensity home-based exercise program of the same duration and dose. Testing at baseline and follow-up has included anthropometry; bone, muscle, and fat mass; and functional performance.

RESULTS

Twenty-eight women (66.1 ± 4.8 years, mean lumbar spine T-score -2.15 ± 0.72) have completed the study. HiPRT and impact loading (n = 12) improved height (0.4 ± 0.2 cm vs -0.3 ± 0.1 cm, p = 0.003), femoral neck bone mineral density (0.3 ± 0.5 % vs -2.5 ± 0.8 %, p = 0.016), lumbar spine bone mineral density (1.6 ± 0.9 % vs -1.7 ± 0.6 %, p = 0.005), and functional performance (p < 0.05), compared to controls (n = 16). Compliance has been >87 %. There have been no injuries.

CONCLUSIONS

Brief supervised HiPRT with impact loading is a safe and effective exercise therapy for postmenopausal women with low to very low bone mass.

Effect of sex and fatigue on single leg squat kinematics in healthy young adults

Background

The single-leg squat (SLS) test is widely used in screening for musculoskeletal injury risk. Little is known, however, of lower limb, pelvis, and trunk kinematics of SLS performance or the effect of sex and fatigue. Our aim was to determine sex differences and the influence of fatigue on SLS kinematics in healthy young adults.

Methods

We recruited 60 healthy men and women between the ages of 20 and 40 years. Three-dimensional kinematic data was collected for SLSs with a ten-camera VICON motion analysis system (Oxford Metrics, UK) before and after a lower limb fatiguing exercise regime. One-way ANCOVA was used to make sex comparisons of kinematic parameters and repeated measures ANOVA was used to determine the effect of fatigue and the interaction with sex.

Results

30 men (25.6 ± 4.8 years) and 30 women (25.1 ± 3.8 years) volunteered to participate. Peak pelvic rotation (3.9 ± 4.1 vs. 7.7 ± 6.2 deg, P = 0.03), peak hip internal rotation (−1.8 ± 5.7 vs. 3.0 ± 7.3 deg, P = 0.02), hip adduction range (11.7 ± 4.8 vs. 18.3 ± 6.7 deg, P = 0.004), and hip rotation range (10.7 ± 3.9 vs. 13.0 ± 4.2 deg, P = 0.04) were smaller for men than for women. Likewise, distance of mediolateral knee motion (180 ± 51 vs. 227 ± 50 mm, P = 0.001) was shorter for men than for women. The kinematic response to fatigue was an increase in trunk flexion, lateral flexion and rotation, an increase in pelvic tilt, obliquity and rotation, and an increase in hip flexion and adduction range (P ≤0.05).

Conclusions

Sex differences in SLS kinematics appear to apply only at the hip, knee, and pelvis and not at the trunk. Fatiguing exercise, however, produces changes at the trunk and pelvis with little effect on the knee.

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.

Swing kinematics of male and female skilled golfers following prolonged putting practice

Given that males and females respond differently to endurance-based tasks, prolonged putting practice may provide an avenue to examine gender-related differences in golf swing kinematics. The aim of this project was to determine if 40 min of putting affects thorax and pelvis kinematics during the full swing of males and females. Three-dimensional trunk kinematics were collected during the swings of 19 male (age: 26 ± 7 years, handicap: 0.6 ± 1.1) and 17 female (age: 24 ± 7 years, handicap: 1.4 ± 1.7) golfers before and after 40 min of putting. Angular displacement at address, top of backswing and ball contact for the pelvis, thorax, and pelvis-thorax interaction were calculated, in addition to the magnitude of peak angular velocity and repeatability of continuous segment angular velocities. Female golfers had less pelvis and thorax anterior-posterior tilt at address, less thorax and thorax-pelvis axial rotation at top of backswing, and less pelvis and thorax axial rotation and pelvis lateral tilt at ball contact pre- to post-putting. Analysis of peak angular velocities revealed that females had significantly lower thorax-pelvis lateral tilt velocity pre- to post-putting. In conclusion, an endurance-based putting intervention affects females' thorax and pelvis orientation angles and velocities to a greater extent than males.

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.

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

Background

The 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.

Methods

Twenty-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 (ICC_3,1) of consistency.

Results

One 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 (ICC_3,1 = 0.71) and students (ICC_3,1 = 0.60), whilst intra-rater reliability was excellent for physiotherapists (ICC_3,1 = 0.81) and good for students (ICC_3,1 = 0.71).

Conclusion

Physiotherapists 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.

Health and health care status of African-born residents of Metropolitan Washington, DC

This study examines health status, health behaviors, and health care access and utilization among African-born residents of the metropolitan Washington, DC area. A telephone survey was administered to a random sample of 525 African-born adults. Results are compared to those for the general local and regional population. Twenty-nine percent of respondents were uninsured; 24% lacked a usual, appropriate source of primary care. Among female respondents, 44% and 34% reported never having had a mammogram or pap smear, respectively. Most health status indicators demonstrated relatively good health, but 15% of respondents reported one of the infectious diseases we investigated. Consumption of alcohol and tobacco was relatively low. African-born residents are generally at risk regarding access to health care, and certain segments (the uninsured, recent arrivals) face critical access barriers. Infectious diseases are a notable feature of health status, and use of some preventive and dental services is considerably lower than for the general population.

Children's access to dental care in Connecticut's Medicaid managed care program

OBJECTIVE

To describe dental care utilization and access problems in Connecticut's Medicaid managed care program, using quantitative and qualitative research methods.

METHODS

Using Medicaid managed care enrollment and encounter data from Connecticut, utilization rates for preventive care and treatment services are determined for 87,181 children who were continuously enrolled in Medicaid managed care for 1 year in 1996-97. Sociodemographic and enrollment factors associated with utilization are identified using bivariate and multivariate methods. Dental providers and practices where children received services are described. Qualitative methods are used to characterize problems experienced by families seeking dental care during the study period.

RESULTS

Only 30.5% of children continuously enrolled in Medicaid managed care for 1 year received any preventive dental services; 17.8% received any treatment services. Children who received preventive care were eight times more likely to have received treatment services. Utilization was higher among (a) younger children, (b) children who lived in Hartford and in other counties served by public dental clinics, and (c) children enrolled in health plans that did not subcontract for administration of dental services. Just 5% of providers, primarily those in public dental clinics, performed 50% of the services. Families whose children needed care encountered significant administrative and logistical problems when trying to find willing providers and obtain appointments.

CONCLUSIONS

Access to dental care is a problem for children in Connecticut's Medicaid managed care program. Several features of managed care have negatively affected access. Public dental clinics served many children across the state and contributed to higher utilization of preventive care and treatment services among children living in Hartford.