Eric M. Lamberg

Cell phones change the way we walk

Cell phone use among pedestrians leads to increased cognitive distraction, reduced situation awareness and increases in unsafe behavior. Performing a dual-task, such as talking or texting with a cell phone while walking, may interfere with working memory and result in walking errors. At baseline, thirty-three participants visually located a target 8m ahead; then vision was occluded and they were instructed to walk to the remembered target. One week later participants were assigned to either walk, walk while talking on a cell phone, or walk while texting on a cell phone toward the target with vision occluded. Duration and final location of the heel were noted. Linear distance traveled, lateral angular deviation from the start line, and gait velocity were derived. Changes from baseline to testing were analyzed with paired t-tests. Participants engaged in cell phone use presented with significant reductions in gait velocity (texting: 33% reduction, p=0.01; talking: 16% reduction, p=0.02). Moreover, participants who were texting while walking demonstrated a 61% increase in lateral deviation (p=0.04) and 13% increase in linear distance traveled (p=0.03). These results suggest that the dual-task of walking while using a cell phone impacts executive function and working memory and influences gait to such a degree that it may compromise safety. Importantly, comparison of the two cell phone conditions demonstrates texting creates a significantly greater interference effect on walking than talking on a cell phone.

Applying principles of motor learning and control to upper extremity rehabilitation

The purpose of this article is to provide a brief review of the principles of motor control and learning. Different models of motor control from historical to contemporary are presented with emphasis on the Systems model. Concepts of motor learning including skill acquisition, measurement of learning, and methods to promote skill acquisition by examining the many facets of practice scheduling and use of feedback are provided. A fictional client case is introduced and threaded throughout the article to facilitate understanding of these concepts and how they can be applied to clinical practice.

Cardiovascular response to treadmill testing in Parkinson disease.

Purpose Exercise has been recommended as a way to maintain quality of life in individuals with Parkinson disease (PD). Experiments examining the cardiovascular response to exercise, however, have yielded controversial results. This study was designed to determine if there is any difference in vital signs and Rate of Perceived Exertion (RPE) between a group of individuals (50–80 years old) with PD and a comparison group of healthy individuals during exercise on a treadmill. Methods Twenty seven volunteers (16 with PD and 11 healthy) participated in this study. Subjects with PD were divided into 2 groups; one that reached target heart rate and one that failed to reach it. In this study, heart rate (HR), systolic blood pressure (BP), and the RPE were measured during a Modified Bruce Protocol. We hypothesized that treadmill testing would result in differences between individuals with PD and healthy subjects when HR and systolic BP were compared at submaximal exercise (defined as Stage 2 of the Modified Bruce Protocol) and at peak exercise (defined as 85% of age predicted target heart rate). Results During submaximal exercise, no significant differences were found between the PD group and the control group for HR, B P, or RPE. At peak exercise, one half of the subjects with PD exhibited blunted cardiovascular responses, despite reaching a comparable intensity of exercise during a Modified Bruce Protocol. Conclusions Although cardiovascular responses to exercise on a treadmill appear similar between individuals with PD and controls at lower levels of exercise, half the subjects with PD in the present study displayed abnormal cardiovascular responses at higher exercise intensities. Administering an exercise stress test will illustrate the expected cardiovascular responses for each individual, therefore guiding exercise prescription.

Norepinephrine and Cardiovascular Responses to Maximal Exercise in Parkinson's Disease On and Off Medication

The aim of this experiment is to understand how Parkinsons disease (PD) medication affects the autonomic responses of individuals during an acute exercise stress test. Fourteen people with PD and fifteen healthy individuals age‐matched between 50 and 80 years performed a modified Bruce protocol. Subjects with PD performed the test once off medication (PD‐off) and then 1 week later on medication (PD‐on). Heart rate (HR), blood pressure (BP), VO2, and norepinephrine (NE) levels were taken at rest and at peak exercise. At peak exercise HR, BP, and NE values for the PD‐on and PD‐off group were all significantly lower than healthy controls, regardless of whether subjects were on their medication. Autonomic abnormalities during exercise in this population appear to be disease manifested and not impactedby medications used to treat PD. We can assume, both on and off medication, this population will show markedly lower BP, HR, and NE responses.

Building a framework for a dual task taxonomy.

The study of dual task interference has gained increasing attention in the literature for the past 35 years, with six MEDLINE citations in 1979 growing to 351 citations indexed in 2014 and a peak of 454 cited papers in 2013. Increasingly, researchers are examining dual task cost in individuals with pathology, including those with neurodegenerative diseases. While the influence of these papers has extended from the laboratory to the clinic, the field has evolved without clear definitions of commonly used terms and with extreme variations in experimental procedures. As a result, it is difficult to examine the interference literature as a single body of work. In this paper we present a new taxonomy for classifying cognitive-motor and motor-motor interference within the study of dual task behaviors that connects traditional concepts of learning and principles of motor control with current issues of multitasking analysis. As a first step in the process we provide an operational definition of dual task, distinguishing it from a complex single task. We present this new taxonomy, inclusive of both cognitive and motor modalities, as a working model; one that we hope will generate discussion and create a framework from which one can view previous studies and develop questions of interest.

Natural breath control during lifting tasks: effect of load.

Anecdotal evidence suggests that people hold their breath during lifting tasks in order to increase intra-abdominal pressure (IAP) and thereby increase lumbar stability. Studies have shown that voluntary control of the breath influences IAP and that increases in IAP are related to increases in lumbar stability. However, a description of naturally occurring breath control during whole-body lifting tasks in normal healthy subjects is currently not available. Therefore, the specific aims of this study were to: (1) determine the naturally occurring breath patterns during lifting tasks in healthy subjects; (2) determine the effects of different levels of load during lifting tasks on natural breath control patterns in healthy subjects. The present study enrolled 20 healthy subjects to describe inspired volume and categories of airflow direction (inspiration, expiration, or breath hold) during two self-paced lifts of crates loaded at 5, 15, and 25% of body weight. When the breath pattern was examined across all loads there was a significant increase in the magnitude of inspired volume and the frequency of occurrence of inspiration immediately prior to lift-off. When examining the effect of load on breath patterns, there was a significant increase of inspired volume and occurrence of breath holding when lifting the heavy load compared to the medium and light loads. These results suggest that: (1) distinct patterns of natural breath control occur during lifting tasks; and (2) breath control is responsive to the timing and magnitude of load lifted.

Individuals with Low Back Pain Breathe Differently Than Healthy Individuals During a Lifting Task

STUDY DESIGN Case control, repeated-measures, experimental laboratory study. OBJECTIVE To determine if, during a whole-body lifting task, individuals with low back pain (LBP) breathe differently than age-matched controls. BACKGROUND Breath control may be optimized to provide increased intersegmental control of the lumbar spine through the generation of intra-abdominal pressure. Consequently, impairments in respiratory and trunk muscle coordination during lifting tasks may contribute to the occurrence or maintenance of LBP. METHODS Participants without LBP (n = 30) were matched by gender and age with those presenting with chronic mechanical LBP (n = 32) of at least 1 year in duration. Participants completed a total of 8 self-paced lifts of a crate from the floor to a table, with the crate empty during 4 of the lifts and loaded to 25% of the participants body weight during 4 of the lifts. The amount of volume in the lungs, measured as a percentage of the individuals vital capacity (%VC), was identified at 9 points during the lifting task. A 2 × 2 × 2 × 9 (group by gender by load by time) mixed-model analysis of covariance (ANCOVA), with age as the covariate, was used to identify differences among conditions and groups of %VC used during the lift. RESULTS Individuals with LBP performed the lifting task with more volume in their lungs (48.2 %VC) than healthy peers (40.9 %VC). Age significantly affected %VC used during the lift: with increasing age, participants with LBP increased inspired volume and participants without LBP decreased inspired volume. CONCLUSIONS Individuals with LBP performed a lifting task with more inhaled lung volume than individuals without LBP. These findings are consistent with the theoretical link between breath control, intra-abdominal pressure, and lumbar segmental control.

Internal representations underlying respiration during object manipulation.

We examined the presence of anticipatory control and the resulting interactions of the respiratory and motor systems during discrete object manipulation. In response to an auditory signal, subjects reached forward, grasped, and lifted an instrumented object weighing 150 or 1000 g while the breathing pattern, fingertip forces, and movements were measured. Following every block of five lifts, the object was removed from sight and replaced with the same or an alternate mass. Thus, the objects weight was predictable during the last lift of each block and unpredictable during the first lift after the transition. When the objects weight was predictable, the force application was faster and inspiratory duration and the tidal volume were reduced for the breath associated with the lift for 1000-g compared to 150-g lifts. Following the transition, when the objects weight was unpredictable, the force application reflected the weight of the object during the previous lift while the respiratory output, regardless of the preceding weight, resembled that used for 1000-g lifts. Additionally, inspiratory duration was significantly correlated with the reach duration in three of the four unpredictable lifting conditions. We conclude that these system-specific anticipatory alterations may arise from a common internal representation that was formed through past manipulatory weight experience.

The 2- and 8-week effects of decompressive brace use in people with medial compartment knee osteoarthritis

Background: Knee osteoarthritis is a prevalent disease. Unloading the affected compartment using a brace is a treatment option. Objectives: To determine whether a decompressive knee brace alters loading in medial knee osteoarthritis following 2 and 8 weeks of use. Study design: Within subjects; pre- and post-testing. Methods: A total of 15 individuals with medial knee osteoarthritis attended four sessions: baseline, fitting, 2 weeks after fitting (post), and 8 weeks after fitting (final). A gait analysis was performed at baseline (without knee brace), post and final. Knee adduction impulse, first and second peak knee adduction moment, knee motion, and walking velocity were calculated. Participants also recorded hours and steps taken while wearing the brace. Results: On average, the brace was worn for more than 6 h/day. Through use of repeated-measures analysis of variance, it was determined that the knee adduction impulse and second peak knee adduction moment were reduced (p < 0.05) at post and final compared to baseline (36% and 34% reduction in knee adduction impulse, 26% reduction in second peak knee adduction moment for post and final, respectively). Furthermore, participants walked faster with increased knee motion during stance. Conclusion: The studied decompressive brace was effective in reducing potentially detrimental forces at the knee—knee adduction impulse and second peak knee adduction moment during the stance phase of gait. Clinical relevance The data from this study suggest that use of a medial unloading brace can reduce potentially detrimental adduction moments at the knee. Clinicians should use this evidence to advocate for use of this noninvasive treatment for people presenting with medial knee osteoarthritis.

Breath control during manual free-style lifting of a maximally tolerated load

Clear evidence links voluntary breath control, intra-abdominal pressure and lumbar stability. However, little is known regarding optimal breath control during manual materials handling. No studies have examined natural breath control while lifting a maximal load. Fourteen healthy subjects lifted a loaded crate from the floor to a table while respiratory flow data were collected. The loads lifted began at 10% of body weight and increased up to 50% (if tolerated) by 5% increments. Data from the minimum, moderate and maximum loads were analysed. Uniform and consistent breath holding during lifting of a maximally tolerated load did not occur. Across all three loads, frequency of inspiration was highest immediately prior to lift-off and significantly higher inspired volume occurred at lift-off of the load compared with preparation for lifting. Holding the breath does not appear to be related to lifting of a maximally tolerated load from floor to table. Statement of Relevance: The findings demonstrate that consistent patterns of naturally occurring breath control during lifting of a maximal load can be identified and do not include uniform breath holding. The findings may assist in creating models for optimal breath control, which will minimise risk of injury during manual material handling tasks.