Restricting lumbar spine flexion redistributes and changes total mechanical energy expenditure during lifting.

Minimizing lumbar spine flexion during lifting requires greater lower extremity joint motion. However, the effects of these kinematic changes on lumbar and lower extremity joint kinetics are unknown. Further, it is unclear whether the distribution of biomechanical demands throughout the lumbar spine and lower extremity during lumbar spine flexion restricted lifting are modulated by task factors like lift origin height and object mass. This study examined the influence of restricting lumbar spine flexion during lifting on the distribution of biomechanical demands, operationalized as mechanical energy expenditure (MEE), across the lumbar spine and lower extremity joints during lifting tasks. Twenty participants performed a series of lifting tasks that varied by lift origin height, object mass and presence or absence of lumbar spine motion restricting harness. MEE was quantified for the lumbar spine and lower extremity joints and summed across all joints to represent the total MEE. Distributions of MEE were compared across combinations of the three task factors. Total MEE was greater when lifting with restricted spine motion (p < 0.001). MEE was redistributed away from the lumbar spine and predominantly to the hips in the spine restricted conditions (p < 0.001). The nature and magnitude of this effect was modulated by lift origin height for the lumbar spine (p < 0.001) and hips (p < 0.001). Findings demonstrated that biomechanical demands can be shifted from the lumbar spine to the lower extremity when lifting with restricted spine flexion, which might help mitigate overuse injuries through coordinative variability.

A systematic review and meta analysis of measurement properties for the flexion relaxation ratio in people with and without non specific spine pain.

This review sought to identify, critically appraise, compare, and summarize the literature on the reliability, discriminative validity and responsiveness of the flexion relaxation ratio (FRR) in adults (≥ 18 years old) with or without spine pain (any duration), in either a clinical or research context. The review protocol was registered on Open Science Framework ( https://doi.org/10.17605/OSF.IO/27EDF ) and follows COSMIN, PRISMA, and PRESS guidelines. Six databases were searched from inception to June 1, 2022. The search string was developed by content experts and a health services librarian. Two pairs of reviewers independently completed titles/abstracts and full text screening for inclusion, data extraction, and risk of bias assessment (COSMIN RoB Toolkit). At all stages, discrepancies were resolved through consensus meetings. Data were pooled where possible with a three-level random effects meta-analyses and a modified GRADE assessment was used for the summary of findings. Following duplicate removal, 728 titles/abstracts and 219 full texts were screened with 23 included in this review. We found, with moderate certainty of evidence, that the cervical FRR has high test-retest reliability and lumbar FRR has moderate to high test-retest reliability, and with high certainty of evidence that the cervical and lumbar FRR can discriminate between healthy and clinical groups (standardized mean difference - 1.16 [95% CI - 2.00, - 0.32] and - 1.21 [- 1.84, - 0.58] respectively). There was not enough evidence to summarize findings for thoracic FRR discriminative validity or the standard error of measurement for the FRR. Several studies used FRR assuming responsiveness, but no studies were designed in a way that could confirm responsiveness. The evidence supports adequate reliability of FRR for the cervical and lumbar spine, and discriminative validity for the cervical and lumbar spine only. Improvements in study design and reporting are needed to strengthen the evidence base to determine the remaining measurement properties of this outcome.

An international consensus on gaps in mechanisms of forced-based manipulation research: findings from a nominal group technique.

Force-Based Manipulation (FBM) including light touch, pressure, massage, mobilization, thrust manipulation, and needling techniques are utilized across several disciplines to provide clinical analgesia. These commonly used techniques demonstrate the ability to improve pain-related outcomes; however, mechanisms behind why analgesia occurs with these hands-on interventions has been understudied. Neurological, neuroimmune, biomechanical, neurovascular, neurotransmitter, and contextual factor interactions have been proposed to influence response; however, the specific relationships to clinical pain outcomes has not been well established. The purpose of this study was to identify gaps present within mechanism-based research as it relates to FBM. An international multidisciplinary nominal group technique (NGT) was performed and identified 37 proposed gaps across eight domains. Twenty-three of these gaps met consensus across domains supporting the complex multisystem mechanistic response to FBM. The strength of support for gaps within the biomechanical domain had less overall support than the others. Gaps assessing the influence of contextual factors had strong support as did those associating mechanisms with clinical outcomes (translational studies). The importance of literature investigating how FBM differs with individuals of different pain phenotypes (pain mechanism phenotypes and clinical phenotypes) was also presented aligning with other analgesic techniques trending toward patient-specific pain management (precision medicine) through the use of pain phenotyping.

The Vehicle Seating Intervention Trial: Cross-Over Randomized Controlled Trial to Evaluate the Impact of 2 Car Seat Configurations on Spinal Posture.

Driving posture can lead to musculoskeletal pain. Most work focuses on the lower back; therefore, we know little about automobile seat design and neck posture. This study evaluated an automobile driver seat that individualized upper back support to improve head and neck posture. Specifically, we examined the system's impact on anterior head translation with secondary outcomes of spine posture and perceptions of comfort/well-being compared with a control. Forty participants were block randomized to experience either the activated or deactivated version of the same seating system first. Participants completed two 30-minute simulated driving trials, separated by washout, with continuous measures of anterior head translation, spine posture, and pelvis orientation. Perceptions of comfort/well-being were assessed by survey and open-ended questions immediately following each condition. Small, but statistically significant decreases in anterior head translation and posterior pelvic tilt occurred with the activated seat system. Participants reported lower satisfaction with the activated seat system. Order of the 2 seat conditions affected differences in pelvis orientation and participant perceptions of comfort/well-being. An anthropometric-based seat system targeting upper back support can significantly affect head and pelvic posture but not satisfaction during simulated driving. Future work should examine long-term impacts of these posture changes on health outcomes.

Can we enable individuals to reach further down without rounding their backs before beginning a lift? Examining the influence of starting foot and trunk position on reach depth.

There is disagreement regarding the efficacy of 'safe' lifting recommendations for reducing low back disorder risk. These recommendations commonly focus on minimising lumbar spine flexion, which limits the range of allowable starting lift positions for that person. This study evaluated whether starting postural adaptations could allow a person to reach down further without rounding their lumbar spine before beginning a lift. Reach displacement was measured as participants performed a series of maximal reach tasks under different combinations of stance width, foot orientation and trunk inclination, with their lumbar spine motion restricted. There were no interactions between any of the three postural adaptations or any effect of stance width or trunk inclination. Seventy-nine percent of participants achieved their greatest reach displacement with their feet externally rotated, which contributed to a 4 cm greater reach displacement compared to a neutral foot orientation (p < 0.001).Practitioner summary: This study examined whether aspects of initial posture could influence the ability to adhere to 'safe' lifting recommendations across a range of lift heights. As a component of lifting (re)training interventions, practitioners should consider starting lift posture adaptations (e.g. manipulating foot external rotation) to improve capacity to adhere to recommendations.

Experience influences kinematic motor synergies: an Uncontrolled manifold approach to simulated Nordic skiing.

Motor synergies are defined as central nervous system mechanisms which adjust participating degrees of freedom to ensure dynamic stability (control) of certain performance variables and have been identified during many motor tasks. The potential for synergistic control of individual segments during full-body tasks is often overlooked. Thus, this study compared individual differences in the potential stabilization of multiple performance variables on the basis of experience during a full-body sport activity. Normalized time series of synergy indices from Uncontrolled Manifold analyses on experienced (n = 9) and inexperienced (n = 19) participants were analysed using statistical parametric mapping during simulated Nordic skiing. Regardless of experience, hand, upper arm, and whole-body centre of mass (COM) kinematics were found to be stabilized by kinematic motor synergies. Only experienced Nordic skiers stabilized trunk COM position at all, while trunk COM velocity was stabilized for a longer duration than inexperienced participants. However, inexperienced participants stabilized hand velocity for a greater duration overall and to a greater magnitude during early pull phase than the experienced skiers. That motor synergies for hand and trunk COM velocity differed between experience groups suggests potential utility for these performance variables as indicators of motor skill development for full-body tasks such as Nordic skiing.

Investigating force-time characteristics of prone thoracic SMT and self-reported patient outcome measures: a feasibility study.

BACKGROUND: Spinal manipulative therapy (SMT) is commonly used to treat musculoskeletal conditions, including thoracic spine pain. Applying patient-specific force-time characteristics are believed to be important to improve SMT's effectiveness. Investigating SMT as part of a multimodal approach is fundamental to account for the complexity of chiropractic clinical practice. Therefore, pragmatic investigations balancing minimal disruptions to the clinical encounter at the same time as ensuring a robust data quality with rigorous protocols are needed. Consequently, preliminary studies are required to assess the study protocol, quality of data recorded and the sustainability of such investigation. Therefore, this study examined the feasibility of investigating SMT force-time characteristics and clinical outcome measures in a clinical setting. METHODS: In this mixed-methods study, providers recorded thoracic SMT force-time characteristics delivered to patients with thoracic spinal pain during regular clinical encounters. Self-reported clinical outcomes of pain, stiffness, comfort during the SMT (using an electronic visual analogue scale), and global rating of change scale were measured before and after each SMT application. Feasibility was quantitatively assessed for participant recruitment, data collection and data quality. Qualitative data assessed participants' perceptions on the impact of data collection on patient management and clinical flow. RESULTS: Twelve providers (58% female, 27.3 ± 5.0 years old) and twelve patients (58% female, 37.2 ± 14.0 years old) participated in the study. Enrolment rate was greater than 40%, data collection rate was 49% and erroneous data was less than 5%. Participant acceptance was good with both providers and patients reporting positive experience with the study. CONCLUSIONS: Recording SMT force-time characteristics and self-reported clinical outcome measures during a clinical encounter may be feasible with specific modification to the current protocol. The study protocol did not negatively impact patient management. Specific strategies to optimize the data collection protocol for the development of a large clinical database are being developed.

Induced leg length inequality affects pelvis orientation during upright standing immediately following a sit-to-stand transfer: a pre-post measurement study.

BACKGROUND: Leg length inequality (LLI) greater than 20 mm has been associated with low back pain (LBP) and its correction is clinically recommended. Much less is known about the biomechanical effects that LLI below 15 mm has on pelvis orientation. METHODS: Twenty-two adult participants (8 female) aged between 18 and 30 years without LBP were enrolled in the study and completed a series of sit-to-stand trials with no heel-lift (0 mm baseline) and heel-lifts of varying heights (5, 9 and 12 mm) placed in their right shoe. Three-dimensional kinematic data were obtained from the lower extremities, pelvis and thorax. Additional kinematic data were obtained from the left and right sides of the pelvis. The global orientation of the whole pelvis and relative orientation between the left and right sides of the pelvis were obtained in upright standing immediately upon completion of the sit-to-stand movement. Repeated measures ANOVAs were used to detect differences in sample means across the different levels of heel-lift (0, 5, 9, and 12 mm). The tests for within-subject effects determined overall significant differences between the means at the different levels of heel-lift induced LLI. Partial Eta-Squared was used to express the size for the main effect of heel-lift height. For each level of heel-lift, the estimated marginal mean and 95% confidence interval (95%CI) values of pelvis angles were illustrated graphically. RESULTS: Left frontal plane rotation of the pelvis increased (p = 0.001), that is, the left side of the pelvis was lower than the right side of the pelvis, and anterior tilt of the pelvis decreased (p = 0.020) with a heel-lift height (applied on the right) as low as 5 mm. A significant main effect of heel-lift was only observed for the norm of rotations about all three axes for relative-pelvis orientation (p = 0.034). Post-hoc analyses did not reveal any statistically significant differences between the heel-lifts and the 0 mm baseline (p≥0.072). CONCLUSION: These findings suggest that correcting leg length inequality below the recommended threshold of 20 mm may influence pelvic orientation. Future work can investigate the effects of the altered orientations on spine loading and the clinical effects of corrections to minor leg length inequality.

Assessing construct validity of the Beighton Score as a measure of generalized joint hypermobility in varsity athletes.

The Beighton Score (BS) is a tool that dichotomizes those who have generalized joint hypermobility (GJH) and those who do not. Unfortunately, the BS is often used in populations that it was not originally developed for, including athletes for screening purposes. The construct validity of the BS remains unknown in this population. This secondary analysis investigated the construct validity of the BS by comparing varsity athletes' passive shoulder and hip ranges of motion (ROMs) to their respective BS and individual forward bend tests (FBTs). There were statistically significant but weak correlations between shoulder ROMs and the BS (r=0.142, p=0.021). Mean hip ROMs were greater by 5-degrees in those with positive FBTs compared to those with negative FBTs. This difference falls within typical measurement errors that occur in practice. Therefore, our results do not support the construct validity of the BS as a measure of GJH in healthy athletes.

Le score de Beighton (BS) est un outil qui permet de distinguer les personnes souffrant d'hypermobilité articulaire généralisée de celles qui n'en souffrent pas. Malheureusement, le score de Beighton est souvent utilisé dans des populations pour lesquelles il n'a pas été conçu à l'origine, notamment les athlètes, à des fins de dépistage. La validité de construit du score de Beighton reste inconnue dans cette population. Cette analyse secondaire a étudié la validité conceptuelle du score de Beighton en comparant les amplitudes de mouvement passives de l'épaule et de la hanche des athlètes universitaires à leur score de Beighton et à leurs tests individuels de flexion avant. Des corrélations statistiquement significatives mais faibles ont été observées entre les amplitudes de mouvement des épaules et le score de Beighton (r=0,142, p=0,021). Les amplitudes moyennes de flexion de la hanche étaient supérieures de 5 degrés chez les personnes ayant subi un test de flexion avant positif par rapport à celles ayant subi un test de flexion avant négatif. Cette différence s'inscrit dans le cadre des erreurs de mesure typiques qui se produisent au cours de la pratique. Par conséquent, nos résultats ne confirment pas la validité conceptuelle du score de Beighton en tant que mesure de l'hypermobilité articulaire généralisée chez les athlètes en bonne santé.

An investigation of the flexion relaxation ratio in adults with and without a history of self-reported low back pain and transient sitting-induced pain.

It is unknown whether the presence of sitting-induced pain or a clinical history of low back pain (LBP) changes spine function outcomes such as the flexion relaxation ratio (FRR). The purpose of this investigation was to determine whether sitting-induced pain or a history of non-specific LBP results in a different FRR. Forty-seven participants were instrumented with surface electromyography over erector spinae at L1, and accelerometers at L1 and S2. Standing maximum lumbar flexion trials were taken preceding and following a 1-hour sitting trial. Pain ratings during sitting and history of LBP were used to group participants for analysis. FRR values taken after the sitting exposures were compared between those that did and did not develop pain during sitting. Baseline FRR values were compared participants with and without a history of LBP. No significant differences in FRR were found for either pain groups (p = 0.11) or clinical history (p = 0.85). Lack of differences may be due to participants not currently experiencing a clinical episode of pain when the ratio was measured and/or because 1-hour sitting exposure was not long enough to induce pain modulation. The findings suggest that neither sitting-induced pain development or clinical history need to be controlled to prevent confounding of FRR.

Synergistic control of hand position, velocity, and acceleration fluctuates across time during simulated Nordic skiing.

A central application of Uncontrolled Manifold (UCM) analysis is the quantification of the presence of motor synergies for the control of task-level variables during human movement. Choosing which task-level variable to analyse is a critical step in UCM analyses because this choice determines a relationship linking the motor performance and motor control. End-effector and/or centre of mass position are frequently chosen as task-level variables, whereas velocity and acceleration receive relatively little attention in this regard. Additionally, UCM analyses are most often conducted on discrete time points of a movement cycle, although these singular time points do not necessarily represent the characteristics of the whole cycle. Accordingly, the purpose of this investigation was to explore synergistic hand control during simulated Nordic skiing. It was hypothesized that 1) hand velocity would be a controlled task-level variable, 2) hand position would not be a controlled task-level variable, and 3) synergistic control of hand kinematics would be fluid (not constant throughout the movement cycle). Seven varsity-level skiers completed a simulated Nordic skiing task, producing specified power outputs on a Nordic skiing ergometer. Normalized time series of indices of task control from UCM analyses were analyzed using statistical parametric mapping. Synergies were observed for all of position, velocity, and acceleration (p < 0.0001), but not for the entire- skiing cycle. Therefore, UCM analyses conducted on discrete time points are not recommended without suitable a priori justification because its outputs fluctuate across time- especially during continuous movements. Velocity and acceleration should be considered in the choice of task-level variables, especially if they help define task performance.

Kinematic adaptations to restricting spine motion during symmetrical lifting.

When lifting an object from the ground a person has many possible whole-body movement solutions to accomplish the task. It is unclear why lifters use most of their available lumbar spine flexion range-of-motion despite many ergonomic guidelines advising against doing so. Experimentally restricting spine motion and observing compensatory movement strategies is one approach to address this knowledge gap. A kinematic analysis was performed on 16 participants who completed symmetrical lifting tasks with and without wearing a spine motion-restricting device. Sagittal trunk, lumbar spine, and lower extremity kinematics, along with stance width and foot orientation in the transverse plane were evaluated between restricted and unrestricted lifting conditions. Restricting spine motion required greater ankle dorsiflexion (p < 0.001), knee flexion (p < 0.001), and hip flexion (p < 0.001) motion in comparison to unrestricted lifting. Motion was reallocated such that hip flexion showed the largest increase in restricted lifting, followed by ankle dorsiflexion, then knee flexion compared to unrestricted lifting. Trunk inclination decreased (i.e., more upright) in restricted compared to unrestricted lifting (p < 0.001). Neither stance width (p = 0.163) nor foot orientation (p = 0.228) were affected by restricting spine motion. These adaptive movements observed indicate lower extremity joint motion must be available and controlled to minimize lumbar spine flexion during lifting.

Characteristics of Forces at the Clinician-Patient and Patient-Table Interfaces During Thoracic Spinal Manipulation in Asymptomatic Adults Are Consistent With Deformable Body Models.

Investigating all forces exerted on the patient's body during high-velocity, low-amplitude spinal manipulative therapy (SMT) remains fundamental to elucidate how these may contribute to SMT's effects. Previous conflicting findings preclude our understanding of the relationship between SMT forces acting at the clinician-patient and patient-table interfaces. This study aimed to quantify forces at the clinician-participant and participant-table interfaces during thoracic SMT in asymptnomatic adults. An experienced clinician provided a posterior to anterior SMT centered to T7 transverse processes using predetermined force-time characteristics to 40 asymptomatic volunteers (20 females; average age = 27.2 [4.9] y). Forces at the clinician-participant interface were recorded by triaxial load cells; whereas, forces at the participant-table interface were recorded by the force-sensing table technology. Preload force, total peak force, time to peak, and loading rate at each interface were analyzed descriptively. Total peak vertical forces at the clinician-participant interface averaged 532 (71) N while total peak forces at the participant-table interface averaged 658 (33) N. Forces at the participant-table interface were, on average, 1.27 (0.25) times larger than the ones at the clinician-participant interface. Larger forces at the participant-table interface compared with the ones at the clinician-participant interface during thoracic SMT are consistent with mathematical models developed to investigate thoracic impact simulating a dynamic force-deflection response.

Prevalence of shoulder problems in youth swimmers in Ontario.

Background: Shoulder problems are common in swimmers. Previous research has focused on elite swimmers. Our research questions were: 1) what is the prevalence of shoulder problems among Ontario age group swimmers and 2) how does prevalence relate to age, sex and years of experience? Methods: A cross sectional survey was administered to youth swimmers from two Ontario clubs. Oslo Sports Trauma Research Centre Overuse Injury Questionnaire (OSTRC) was used to assess four-week prevalence of shoulder problems. Prevalence (%) with 95% confidence intervals (95% CI) was constructed and prevalence across age, sex and years of experience was investigated using cross-tabulations and chi-square tests. Results: There were 83 surveys completed (response rate 50%). The 4-week prevalence of shoulder pain was 35% (95% CI 25%, 45%). Shoulder problems were not significantly related to age, sex or years of experience. Conclusion: These results can inform future studies on injury prevention and risk mitigation strategies in swimmers.

Contexte: Les problèmes à l'épaule sont courants chez les nageurs. Les recherches antérieures ont porté sur les nageurs d'élite. Nos questions de recherche étaient les suivantes: 1) quelle est la prévalence des problèmes à l'épaule chez les nageurs des groupes d'âge de l'Ontario et 2) comment la prévalence est-elle liée à l'âge, au sexe et aux années d'expérience? Méthodologie: Une enquête transversale a été menée auprès des jeunes nageurs de deux clubs de l'Ontario. Le questionnaire sur les blessures de surmenage de l'Oslo Sports Trauma Research Centre (OSTRC) a été utilisé pour évaluer la prévalence des problèmes à l'épaule sur quatre semaines. La prévalence (%) avec des intervalles de confiance à 95 % (IC 95 %) a été établie et la prévalence en fonction de l'âge, du sexe et des années d'expérience a été étudiée à l'aide de tableaux croisés et de tests du chi carré. Résultats: L'enquête a obtenu un taux de réponse de 50 % (83 questionnaires remplis). La prévalence des douleurs à l'épaule sur 4 semaines était de 35 % (IC 95 % 25 %, 45 %). Les problèmes à l'épaule n'étaient pas considérablement liés à l'âge, au sexe ou aux années d'expérience. Conclusion: Ces résultats peuvent éclairer les futures études sur la prévention des blessures et les stratégies de réduction des risques chez les nageurs.

Dynamic Balance is Similar Between Lower Extremities in Elite Fencers.

BACKGROUND: Few studies have quantified dynamic balance in fencers despite previous suggestions that balance training may be beneficial for these athletes. Generally, asymmetry in dynamic balance performance between the left and right legs can be an indicator of lower extremity injury risk and used to monitor rehabilitation progress. Fencing is recognized as an asymmetric sport, therefore, differences in dynamic balance may exist among uninjured athletes. HYPOTHESIS/PURPOSE: The primary objective of this investigation was to evaluate whether asymmetry of dynamic balance is present in uninjured national-level fencers. It was hypothesized that elite uninjured fencers would demonstrate superior dynamic balance on the lead-leg of their fencing stance. A secondary objective was to compare dynamic balance performance of elite fencers to previously published data from high-level athletes participating in other sports. STUDY DESIGN: Descriptive Laboratory Study. METHODS: Fourteen uninjured elite competitive fencers were recruited. Subjects self-reported the lead leg of their fencing stance. Each participant performed the Y-Balance test (YBT), which represented a measurement of dynamic balance control, on both legs. Reach distances were recorded directly from a commercially available YBT apparatus. Four reach distances were recorded: anterior, posteromedial, posterolateral, and a composite measure was calculated. Distances were leg length-normalized and expressed as a percentage. Sample averages and standard deviations were derived for the four YBT measurements. RESULTS: There were no significant differences in reaching distance between the lead and trail legs in any of the four YBT measures (p ≥ 0.65). Fencers appeared to demonstrate larger normalized reach distances in the posterolateral and posteromedial directions than other athletes. CONCLUSIONS: The results of this study indicate that dynamic balance is not significantly different between the lead and trail legs in elite fencers, despite the asymmetrical nature of their sport. The apparent symmetry of dynamic balance control in uninjured fencers means that the YBT could be used in this population for monitoring progress during training and rehabilitation. LEVEL OF EVIDENCE: 2b.

A Kinematic Comparison Between Sit-to-Stand Movements and Individual Cycles of the 5-Cycle Sit-to-Stand Test.

OBJECTIVE: The 5-cycle sit-to-stand (5XSTS) test is frequently used to test physical function for different clinical populations, with time to complete as the measured outcome. This study evaluated the similarity of kinematics between a single cycle of the STS movement and individual cycles of the 5XSTS test. METHODS: Lower extremity, pelvis, and thorax kinematic data were monitored as 20 participants (aged 18-40) completed 5 trials of the STS movement and 1 trial of the 5XSTS test. Correlations and root mean squared differences assessed the temporal and spatial similarities in kinematic patterns of sagittal plane joint angles at the ankles, knees, hips, and spine between single cycles of the STS movement and individual cycles of the 5XSTS test. Peak joint angles were obtained along with discrete angles at the start, seat off, and end of the movement. RESULTS: Temporal and spatial similarity of kinematics for the ankles and hips were reduced over cycles 2 to 5 of the 5XSTS. Increased hip flexion was observed at the start of cycles 2 to 5 of the 5XSTS test. Increased knee and hip flexion were observed at the end of cycles 1 to 4 of the 5XSTS test. CONCLUSIONS: Temporal patterns of sagittal plane joint angles captured in the first cycle of the 5XSTS represented those adopted for an isolated STS movement. Different initial conditions for cycles 2 to 5 of the 5XSTS 58 may have reduced temporal and spatial similarity of sagittal plane joint angles of the ankles and hips.

Characterization of thoracic spinal manipulation and mobilization forces in older adults.

BACKGROUND: Spinal mobilization and spinal manipulation are common interventions used by manual therapists to treat musculoskeletal conditions in older adults. Their force-time characteristics applied to older adults' thoracic spine are important considerations for effectiveness and safety but remain unknown. This study aimed to describe the force-time characteristics of posterior-to-anterior spinal mobilization and manipulation delivered to older adults' thoracic spine. METHODS: Twenty-one older adults (≥65 years) with no thoracic pain received posterior-to-anterior thoracic spinal mobilization and/or manipulation with the force characteristics a chiropractor deemed appropriate. Six-degree-of-freedom load cells and an instrumented treatment table recorded the force characteristics of both interventions at the clinician-participant and participant-table interfaces, respectively. Preload force, total peak force, time to peak and loading rate were analyzed descriptively. FINDINGS: Based on data from 18 adults (56% female; average: 70 years old), mean resultant spinal mobilization forces at the clinician-participant interface were: 220 ± 51 N during preload, 323 ± 67 N total peak force, and 312 ± 38 ms time to peak. At the participant-table interface, mobilization forces were 201 ± 50 N during preload, 296 ± 63 N total peak force, and 308 ± 44 ms time to peak. Mean resultant spinal manipulation forces at the clinician-participant interface were: 260 ± 41 N during preload, 470 ± 46 N total peak force, and 165 ± 28 ms time to peak. At the participant table interface, spinal manipulation forces were 236 ± 47 N during preload, 463 ± 57 N total peak force, and 169 ± 28 ms time to peak. INTERPRETATION: Results suggest older adults experience unique, but comparable force-time characteristics during spinal mobilization and manipulation delivered to their thoracic spine compared to the ones delivered to younger adults described in the literature.

Effect of Drop-Piece High-Velocity, Low-Amplitude Manipulation to the Midfoot of Asymptomatic Adult Sprinters on Performance During a Unilateral Horizontal Drop-Jump Test: A Feasibility Investigation.

OBJECTIVE: The purpose of this study was to investigate the feasibility of measuring the immediate effects of drop-piece high-velocity, low-amplitude (DP-HVLA) manipulation to the midfoot region on jump distance in competitive adult sprinters during a standardized unilateral horizontal drop-jump (U-HDJ) test. METHODS: Seven asymptomatic competitive adult sprinters (4 women) were recruited for this study. Testing was conducted on the dominant leg. Participants completed a 10-minute self-selected warm-up, followed by a 6-jump familiarization period with the U-HDJ test. All participants completed 3 U-HDJ trials before and after receiving DP-HVLA chiropractic manipulation to the joints of the midfoot assessed as being hypomobile by a licensed sports chiropractor. The primary outcome of the U-HDJ test was horizontal displacement, measured using an optoelectronic motion-capture system. Mean, SD, and 95% confidence intervals were determined for the posttreatment change in jump distance. A single-sample t test with α = 0.05 assessed the posttreatment change in jumping distance. RESULTS: We were able to measure immediate effects. The preliminary findings showed an increase in jump distance after DP-HVLA manipulation to the midfoot region (mean = 0.06 m, SD = 0.05 m; P = .014; 95% confidence interval, 0.02-0.11; effect size = 1.30). CONCLUSION: This study demonstrates that it was feasible to measure immediate improvement in performance after DP-HVLA chiropractic manipulation in a clinical assessment with correlation to sprinting performance in a population of elite sprinters. As this was a feasibility study, the small sample size, overlapping confidence intervals, and specific niche population limit the extrapolation of these findings.

The Impact of Moderate and High Intensity Cardiovascular Exertion on Sub-Elite Soccer Referee's Cognitive Performance: A Lab-Based Study.

Soccer referees represent a specialized population who are required to perform decisional or perceptual tasks during physical exertion. Recent studies have demonstrated that submaximal acute exercise has a positive impact on cognitive performance. However, less is known about the impact of more strenuous exertion on cognitive performance. This study assessed the effect of moderate and maximal intensity exercise exertion on a cognitive performance in sub-elite soccer referees. Twelve experienced soccer referees (4 female, 8 male) were recruited. Data were collected on 2 separate days. Baseline fitness level was assessed by a standardized aerobic capacity test (VO2max Test) on Day 1, along with practice trials of the Stroop Color Word Test (Stroop Test) for evaluating cognitive performance. On Day 2, cognitive performance was assessed before, during, and after an incremental intensity exercise protocol based on the Fédération International de Football Association (FIFA) referee fitness test. Relative to results obtained at rest performance on the Stroop Test improved at moderate exertion and at maximal exertion during the modified FIFA fitness test (F = 18.97, p = .005). Mean time to completion (in seconds) of the interference Stroop task significantly improved (p < .05) between rest and moderate exertion [-3.0 ± 3.0 seconds] and between rest and maximal exertion [-4.8 ± 2.6 seconds]. In summary, we observed that cognitive performance was found to improve when sub-elite soccer referees performed moderate and maximal exercise relative to results obtained at rest. It is possible that referees focus their attention to improve goal-oriented processing in the brain during physical exertion.