Publications by authors named "Dennis J Larson"

Differences in coordination and coordinative variability are common in people with low back pain. While differences may relate to the different analyses used to quantify these metrics, the preferred approach remains unclear. We aimed to compare coordination and coordinative variability, in people with and without low back pain performing a lifting/lowering task, using continuous relative phase and vector coding procedures, and to identify which technique better detects group differences.

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The association between low back pain and lumbar spine local dynamic stability (LDS) appears to be modulated by if and how someone catastrophizes about pain, suggesting that the cognitive perceptions of pain may influence an individual's ability to control lumbar spine motion. Previous work also demonstrates that directing cognitive resources and attentional focus can influence movement performance. Therefore, we aimed to examine whether distracting attentional focus would influence lumbar spine LDS during repetitive flexion-extension movements.

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Background: The large number of articulating joints within the spinal column provides an abundance of options to control its movement. However, the ability of individuals to consciously manipulate these movement options is poorly understood.

Objectives: To determine if short-term training can improve the ability to consciously dissociate motion between the pelvis and thorax during repetitive pelvic tilting movements.

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Article Synopsis
  • This study examined how different metronome paces affect the stability and coordination of lumbar spine motion during repetitive lifting tasks.
  • Ten participants performed trials at their own pace and at paces of 10, 15, and 20 lifts per minute, revealing that the 15 lifts/min pace was preferred.
  • Results showed that while metronome pacing improved lumbar spine stability, thorax-pelvis coordination variability was highest at the slowest pace (10 lifts/min); thus, using a metronome requires careful consideration when studying movement patterns.
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Augmented tactile and performance feedback has been used to (re)train a modified lifting technique to reduce lumbar spine flexion, which has been associated with low back disorder development during occupational repetitive lifting tasks. However, it remains unknown if the presence of trunk extensor neuromuscular fatigue influences learning of this modified lifting technique. Therefore, we compared the effectiveness of using augmented tactile and performance feedback to reduce lumbar spine flexion during a repetitive lifting task, in both unfatigued and fatigued states.

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Lifting with a flexed spine, especially near the end range of motion, has been identified as a potential risk factor for low back injury/pain. Therefore, individuals who develop discomfort from repetitive, prolonged and/or loaded flexed or slouched postures may benefit from a greater awareness of how to control and/or modify their spinal posture to avoid irritating their backs in these situations. This study was therefore designed to test the ability of spine-oriented verbal instructions to reduce intersegmental spine flexion during three lifting tasks.

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Article Synopsis
  • - Previous research shows that people's stability responses in the lumbar spine differ when they experience back muscle fatigue, leading to adjustments in coordination across multiple joints.
  • - This study involved 30 participants who performed two trunk flexion-extension trials (one when rested and one when fatigued) to assess stability, coordination, and variability during movements.
  • - Findings revealed that about 30% of participants became more stable when fatigued, 17% became less stable, and 53% showed no change, indicating diverse responses to fatigue and a tendency for more coordinated movement patterns overall.
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Cognitive motor interference (CMI) is a psychomotor phenomenon characterized by alterations in kinematic spatial-temporal parameters during concurrent cognitive and motor tasks (i.e. dual-tasking).

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Prolonged or repetitive spine flexion induces creep deformation of posterior spine tissues allowing for increased intervertebral motion beyond 'normal' limits, which may influence sub-regional (intersegmental) spine motion during subsequent manual lifting tasks. Using spine skin-surface kinematics, intersegmental lumbar spine motion was recorded over 20 minutes of prolonged static spine flexion and a subsequent manual lifting task (2 lifts every 3 minutes, 30 minutes total) in 14 participants. Results demonstrated that mid to lower lumbar intersegmental levels (i.

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Unlabelled: During play, ice hockey goaltenders routinely dehydrate through sweating and lose ≥2% body mass, which may impair thermoregulation and performance.

Purpose: This randomized, crossover study examined the effects of mild dehydration on goaltender on-ice thermoregulation, heart rate, fatigue, and performance.

Methods: Eleven goaltenders played a 70-minute scrimmage followed by a shootout and drills to analyze reaction time and movements.

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Using a technique of tracking intersegmental spine kinematics via skin surface markers, this study aimed to estimate local dynamic spine stability across smaller sub-regions (or segments) of the lumbar spine while also considering the impact of an external pelvic constraint during repetitive movements. Sixteen participants (10 males) performed two trials [Free Motion (FM), Pelvis Constrained (PC)] each consisting of 65 repetitive trunk flexion-extension movements to assess dynamic spine stability using maximum Lyapunov exponents (LyE). First, results indicated that LyE obtained from analysis of 30 repetitive flexion-extension movements did not differ from those obtained from analysis of greater numbers of repetitive movements, which aligns with results from a previous study for the whole lumbar spine.

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This study was designed to assess the utility of using a measure of dynamic spine stability in an unfatigued, rested state as a predictor of dynamic spine stability in a challenged, fatigued state. Participants completed three trials (Day 1: Rested, Fatigued; Day 2: Recovery) during which the dynamic stability of the spine was assessed over 30 repeated flexion/extension motions using maximum finite-cycle Lyapunov exponents. Multiple sets of dynamic trunk extensions were performed to fatigue the trunk extensor muscles.

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The purpose of this study was to induce both trunk extensor and abdominal muscle fatigue, on separate occasions, and compare their effects on standing postural control and trunk proprioception, as well as look at the effects of a recovery period on these outcome measures. A total of 20 individuals participated, with 10 (5 males and 5 females) completing either a standing postural control or lumbar axial repositioning protocol. Participants completed their randomly assigned protocol on two occasions, separated by at least 4  days, with either their trunk extensor or abdominal muscles being fatigued on either day.

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Objective: To compare upper extremity muscle activity and workload between simulated open surgery, multiple port laparoscopic surgery (MLS), and single incision laparoscopic surgery (SLS) techniques in veterinary students.

Study Design: Pilot study.

Population: Veterinary students (n = 10) from years 1 to 4.

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The purpose of the current work was to (1) determine whether low back cutaneous sensitivity could be reduced through the use of a topical lidocaine-prilocaine anesthetic (EMLA(®)) to mirror reductions reported in chronic lower back pain (CLBP) patients, as well as to (2) identify whether reductions in cutaneous sensitivity resulted in decreased lumbar spine proprioception, neuromuscular control and dynamic stability. Twenty-eight healthy participants were divided equally into matched EMLA and PLACEBO treatment groups. Groups completed cutaneous minimum monofilament and two-point discrimination (TPD) threshold tests, as well as tests of sagittal and axial lumbar spine active repositioning error, seated balance and repeated lifting dynamic stability.

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