Association between muscle hydration measures acquired using bioelectrical impedance spectroscopy and magnetic resonance imaging in healthy and hemodialysis population

Establishing the effect of fluctuating extracellular fluid (ECF) volume on muscle strength in people with end-stage renal disease (ESRD) on hemodialysis (HD) is essential, as inadequate hydration of the skeletal muscles impacts its strength and endurance. Bioelectrical impedance spectroscopy (BIS) has been a widely used method for estimating ECF volume of a limb or calf segment. Magnetic resonance imaging (MRI)-acquired transverse relaxation times (T2) has also been used for estimating ECF volumes of individual skeletal muscles. The purpose of this study was to determine the association between T2 (gold standard) of tibialis anterior (TA), medial (MG), and lateral gastrocnemius (LG), and soleus muscles and calf BIS ECF, in healthy and in people with ESRD/HD. Calf BIS and MRI measures were collected on two occasions before and after HD session in people with ESRD/HD and on a single occasion for the healthy participants. Linear regression analysis was used to establish the association between these measures. Thirty-two healthy and 22 participants on HD were recruited. The association between T2 of TA, LG, MG, and soleus muscles and ratio of calf BIS-acquired ECF and intracellular fluids (ICF) were: TA: β = 0.30, P > 0.05; LG: β = 0.37, P = 0.035; MG: β = 0.43, P = 0.014; soleus: β = 0.60, P < 0.001. For the HD group, calf ECF was significantly associated with T2 of TA (β = 0.44, P = 0.042), and medial gastrocnemius (β = 0.47, P = 0.027) following HD only. Hence BIS-acquired measures cannot be used to measure ECF volumes of a single muscle in the ESRD/HD population; however, BIS could be utilized to estimate ratio of ECF: ICF in healthy population for the LG, MG, and soleus muscles.

Enacting Fall Prevention in Community Outreach Care

Despite increased international concern about fall prevention throughout the past 20 years, only limited attention has been paid to the experiences and perspectives of health care providers who deliver fall prevention programs. The purpose of this interpretive phenomenological study was to explore the meaning of the experience of enacting fall prevention, through individual semistructured interviews, among 6 members of an interprofessional geriatric outreach team in Ontario, Canada. Findings suggest that enacting careful practice was essential to the experience of enacting fall prevention, represented by four interrelated phenomenological themes: caring fully for older clients, carefully seeing older clients in their life contexts, enacting therapeutic relationships, and experiential learning in interprofessional teams. We discuss findings in relation to literature on emotional labor, leading to suggestions for the policy and practice of fall prevention.

"Any movement at all is exercise": a focused ethnography of rural community-dwelling older adults' perceptions and experiences of exercise as self-care

PURPOSE

To understand rural community-dwelling older adult participants' shared values, beliefs, and behaviours related to exercise as self-care.

METHODS

We conducted a constructivist-focused ethnography involving semi-structured interviews and participant observation with 17 individuals 65 years and older. Interviews were transcribed and inductively coded to develop themes related to exercise, self-care, and exercise as self-care. Field notes were triangulated with follow-up interviews and dialogue between authors to enhance interpretation.

RESULTS

Participants described exercise broadly as movement and not as a central self-care behaviour. However, awareness of the importance and health-related benefits of exercise increased after a significant personal health-related event. Participants preferred exercise that was enjoyable and previously experienced.

CONCLUSIONS

Prescribing exercise for older adults may be particularly effective if the focus is on enjoyable and previously experienced physical activity and if it incorporates interpretation of exercise guidelines and training principles in relation to chronic conditions and potential health benefits.

'Getting back to real living': A qualitative study of the process of community reintegration after stroke

OBJECTIVES

To examine the process of community reintegration over the first year following stroke, from the patient's perspective.

DESIGN

Qualitative, longitudinal, grounded theory study involving ten participants. During the first year post discharge from inpatient rehabilitation, 46 one-on-one semi-structured interviews were conducted with ten participants. Interviews were completed with participants before discharge from inpatient stroke rehabilitation and in their homes at two weeks, three months, six months and one year post discharge. Analysis was guided by grounded theory methods described by Corbin and Strauss.

SUBJECTS

Four women and six men (mean age 59.6 ± 18.0, all with left hemiparesis and without aphasia) who had sustained their first hemispheric stroke and were returning to the community following inpatient rehabilitation.

RESULTS

The process of community reintegration after stroke involved transitioning through a series of goals: gaining physical function, establishing independence, adjusting expectations and getting back to real living. The ultimate challenge for stroke survivors during this process of community reintegration was to create a balance between their expectations of themselves and their physical capacity to engage in meaningful roles.

CONCLUSIONS

Over the first year after stroke, participants reported that the process of community reintegration was marked by ongoing changes in their goals. Formal and informal caregivers need to work with stroke survivors living in the community to facilitate realistic and achievable goal setting. Tools which identify meaningful activities should also be incorporated to provide stroke survivors with the opportunity to contribute and engage with others in the community.

Pragmatism in practice: mixed methods research for physiotherapy

The purpose of this paper is to provide an argument for the place of mixed methods research across practice settings as an effective means of supporting evidence-based practice in physiotherapy. Physiotherapy practitioners use both qualitative and quantitative methods throughout the process of patient care-from history taking, assessment, and intervention to evaluation of outcomes. Research on practice paradigms demonstrates the importance of mixing qualitative and quantitative methods to achieve 'expert practice' that is concerned with optimizing outcomes and incorporating patient beliefs and values. Research paradigms that relate to this model of practice would integrate qualitative and quantitative types of knowledge and inquiry, while maintaining a prioritized focus on patient outcomes. Pragmatism is an emerging research paradigm where practical consequences and the effects of concepts and behaviors are vital components of meaning and truth. This research paradigm supports the simultaneous use of qualitative and quantitative methods of inquiry to generate evidence to support best practice. This paper demonstrates that mixed methods research with a pragmatist view provides evidence that embraces and addresses the multiple practice concerns of practitioners better than either qualitative or quantitative research approaches in isolation.

Threshold Berg balance scale scores for gait-aid use in elderly subjects: a secondary analysis

PURPOSE

To determine the threshold Berg Balance Scale (BBS) scores that discriminate among levels of gait-aid use in elderly subjects.

METHODS

A secondary analysis of data combined from two projects was performed. Both projects determined BBS performance, self-selected gait speed, and gait-aid use in samples of community-dwelling, independently ambulant individuals older than 65 years of age. Receiver operating characteristic curves were used to identify BBS scores that optimized identification of individuals with different levels of ambulation.

RESULTS

Previously determined associations between BBS score and various indicators of ambulatory ability were reproduced with the combined data set. Threshold BBS scores were identified for ability to walk without an aid (≥49/56) and ability to walk without a four-wheeled walker (≥43/56). The percent agreement values for the identified threshold scores ranged from 51% to 87%.

CONCLUSIONS

Although some threshold BBS scores could be determined, the accuracies of the scores render them of limited use for guiding gait-aid prescription in individual clients.

Clinical utility of the 2-minute walk test for older adults living in long-term care

PURPOSE

This study's purposes were to examine the measurement properties of the 2-minute walk test (2MWT), to illustrate the use of reliability coefficients in clinical practice, and to estimate sample size for a subsequent validity study.

METHOD

Sixteen residents of long-term care (LTC; mean age = 87 years) completed two 2MWTs with Rater A and two 2MWTs with Rater B on test days 1 and 2, approximately 1 week apart. On a third test day, subjects completed one trial of the Berg Balance Scale (BBS), timed up-and-go (TUG) test, and 6-minute walk test (6MWT) with Rater A. On 2 other test days, approximately 1 week apart, Rater A administered the 2MWT to five older adults living in a retirement facility. Absolute and relative reliability and concurrent and known-groups validity coefficients were calculated.

RESULTS

No main effect for rater, trial, or occasion was found. Test-retest reliability estimates of 0.94 and 0.95 were obtained. The 2MWT demonstrated concurrent validity (r > or = 0.84) with the BBS, TUG, and 6MWT. Comparison of distance walked by LTC and retirement residents showed a difference of 72.9 m (95% CI: 44.2, 101.6). The results suggest that 90% of truly stable older adults will display random fluctuations in 2MWT performance within a boundary of 15 m.

CONCLUSION

The 2MWT had sound measurement properties in this sample of LTC residents. Based on our results, 24 subjects would be required for a subsequent hypothesis-testing validity study.

"Holding me back": living with arthritis while recovering from stroke

OBJECTIVE

To describe the experience of living with arthritis while recovering from stroke.

DESIGN

Qualitative, phenomenological study. During the first three months post-stroke, 14 one-on-one semi-structured interviews were conducted. Analysis was guided by the modified van Kaam method.

SETTING

General community.

PARTICIPANTS

Three men and two women with self-reported pre-existing knee arthritis who were recovering from a first stroke.

INTERVENTION

Not applicable.

MAIN OUTCOME MEASURES

Not applicable.

RESULTS

"Holding me back" was central to the experience of living with knee arthritis while recovering from stroke, due to pain, mobility limitations, frustration, and additional coping demands. Experiencing arthritic pain occurred during daily physical activity. As a result, arthritis interfered with participants' ability to fully engage in stroke rehabilitation. The resulting mobility limitations due to arthritis were frustrating experiences that required additional coping strategies by all participants.

CONCLUSIONS

From the perspective of the participants, the slowed recovery from stroke due to arthritis illustrated the need to consider the influence of knee arthritis on stroke recovery during inpatient rehabilitation and after discharge. Stroke rehabilitation interventions that emphasize weight-bearing exercise may not be tolerated by those with arthritis. Alternate pharmacological treatments and physical rehabilitation should be considered for people with pre-existing knee arthritis post-stroke.

Utility of portable electromyography for quantifying muscle activity during daily use

BACKGROUND

Mobility has been studied using performance, questionnaire, pedometer and accelerometer measures, but these tools do not provide information about muscle activity. To better understand mechanisms associated with movement impairment as they relate to function, it is valuable to quantify muscle activity during everyday activities.

OBJECTIVE

This report presents electromyography (EMG) during daily activities from the affected and unaffected limbs of a 74-year-old man who survived a stroke 12 years ago, compared to 7 older healthy men who had not experienced a stroke.

METHODS

The biceps brachii, triceps brachii, quadriceps and hamstring muscles were recorded continuously for one 8-hour session in the unaffected limbs of the stroke survivor and control subjects. On a second day, EMG from these same muscles of the affected side was recorded for 4 h. Bursts (amplitude >2% maximum effort, duration >0.1 s) and gaps (amplitude <1% maximum effort, duration >0.1 s) of EMG were quantified for the number of times they occurred, mean event duration (seconds), mean peak amplitude (percent maximum voluntary efforts) and rate of activity (event activity/second).

RESULTS

Burst and gap patterns of the unaffected limb muscles were similar between the stroke survivor and controls. Increased numbers of bursts (approx. 40%) and gaps (approx. 44%) were seen in the subject's lower limb muscles of his affected versus unaffected side. Biceps brachii burst activity of the affected limb was increased, whereas triceps brachii burst activity was decreased. These muscle activity changes in the affected limb suggest that the triceps brachii was relatively inactive and the biceps brachii and lower limb muscles were active in an 'on' and 'off' pattern.

CONCLUSION

Muscle activity in the unaffected limb of the stroke survivor was similar compared to control subjects, but the affected limb differed from the unaffected after stroke. Portable EMG to monitor muscle activity for prolonged periods was not reported to be an impediment by the case or control subjects. Using this technology, EMG bursts and gaps can be recorded and used to describe muscle activity. Future work may consider the feasibility of this technique to monitor rehabilitation progression or long-term plasticity of muscle activity.

Reliability and Validity of Responses to Submaximal All-Extremity Semirecumbent Exercise in Older Adults

Although popular in clinical settings, little is known about the utility of all-extremity semirecumbent exercise machines for research. Twenty-one community-dwelling older adults performed two exercise trials (three 4-min stages at increasing workloads) to evaluate the reliability and validity of exercise responses to submaximal all-extremity semirecumbent exercise (BioStep). Exercise responses were measured directly (Cosmed K4b2) and indirectly through software on the BioStep. Test–retest reliability (ICC2,1) was moderate to high across all three stages for directly measured METs (.92, .87, and .88) and HR (.91, .83, and .86). Concurrent criterion validity between the K4b2and BioStep MET values was moderate to very good across the three stages on both Day 1 (r= .86, .71, and .83) and Day 2 (r= .73, .87, and .72). All-extremity semirecumbent submaximal exercise elicited reliable and valid responses in our sample of older adults and thus can be considered a viable exercise mode.

Maximal Aerobic Capacity Testing of Older Adults: A Critical Review

Most of the data that describe maximal oxygen uptake (VO(2max)) and the requirements for its attainment have been developed using young adults as subjects. Many older adults are unable to satisfactorily complete a maximal exercise effort in a standard exercise stress test. This review describes exercise tests currently available to measure VO(2max) in older adults. PubMed and CINAHL databases were searched for studies including healthy individuals older than 65 years with reproducible descriptions of the testing protocol. The research on VO(2max) testing in healthy individuals older than 65 years is limited, does not describe the protocols in detail, and/or lacks information on the psychometric properties of the exercise tests. There is a need for refinement of the few existing protocols for testing aerobic capacity in older adults, as well as the development of new protocols specifically applicable to older adults. Consensus on the criteria defining VO(2max) attainment during exercise in older adults is required, as well as agreement on the most appropriate exercise protocols and equipment, specific to older adults, to successfully fulfil these criteria.

Reliability and validity of ankle proprioceptive measures

OBJECTIVE

To determine the reliability and validity of ankle proprioceptive measures.

DESIGN

Reliability was assessed between test occasions. Construct validity was addressed by the ability of measures to differentiate among groups.

SETTING

Laboratory of an educational institution.

PARTICIPANTS

Eight healthy adults were recruited into each of 3 groups: (1) young (20-39y), (2) middle-aged (40-59y), and (3) older adults (>or=60y). Four subjects from each group (n=12) participated in retesting.

INTERVENTIONS

Not applicable.

MAIN OUTCOME MEASURES

Threshold for perception of passive movement, error in active reproduction of position, error in reproduction of velocity, and error in reproduction of torque.

RESULTS

Intersession reliability was excellent (intraclass correlation coefficient [ICC] range, .79 - .95) for threshold for perception of movement, error in active reproduction, error in velocity reproduction, and error in dorsiflexion torque reproduction; intersession reliability was good for error in reproduction of plantarflexion torque (ICC=.72). Threshold for perception of movement differed between groups 1 and 3 and between groups 2 and 3 (P<.05). Error in reproduction of position was greater in group 2 than in group 1 (P<.05).

CONCLUSION

Differences in proprioception between the older and the 2 younger groups were best detected by using threshold for perception of passive movement.

Effects of isokinetic strength training on concentric and eccentric torque development in the ankle dorsiflexors of older adults

This study quantifies concentric and eccentric dorsiflexor muscle torque at various movement velocities and determines the neuromuscular effects from short-term practice of repeated maximal voluntary contractions using an isokinetic resisted exercise program in older adults. Twenty-eight subjects (76.3+/-4.6 years) trained concentric and eccentric dorsiflexion 3 days per week for 2 weeks at 30 degrees, 90 degrees, and 180 degrees/s through 40 degrees of dorsiflexion range of motion. Peak torque, rate of torque development, surface electromyography, and strength curves at each velocity were compared before and after training. Increases were found for concentric (27%) and eccentric (20%) dorsiflexor peak torque and concentric rate of torque production (20%-53%) across all movement velocities (p < .01). Training also significantly increased dorsiflexor concentric (64%) and eccentric (55%) surface electromyography; taken together, this is evidence of apparent adaptation of neural factors in older adults with short-term training. These findings support that eccentric and concentric strength training enhances the control and production of ankle muscle dorsiflexor torque in older adults, with implications for improving functional mobility of the ankle joint.

Motor skill learning of concentric and eccentric isokinetic movements in older adults

Neuromuscular adaptation at the onset of resisted exercise can be observed as increases in torque and surface electromyography. The effect of learning the motor task has been hypothesized to contribute to these early increases, especially for older people. Thus, the purpose of this study was to investigate the facilitatory effects of practice on motor performance in older adults during short-term isokinetic training of the ankle dorsiflexors (DF). Twenty-eight men and women (M = 76.3 +/- 4.6 years) volunteered for a 2-week, 3-days/week strength training program. They were tested in a sitting position on a KinCom isokinetic dynamometer at 30, 90, and 180 degrees s-1 through 40 degrees of DF movement (concentric and eccentric contractions). Criterion curves of lever arm angle patterns were cross-correlated with subject-generated angle patterns, showing significantly better correlations on posttest versus baseline. Smoothness and proficiency of muscle contraction improved with practice by fewer hesitations in movement and increased ability to change between concentric and eccentric muscle contractions. Increased agonist electromyography and torque were hypothesized to be secondary to greater neural drive and/or synchronization of motor unit firing rate and/or recruitment during maximal voluntary contraction, improved coordination, and adapted neural control of concentric and eccentric muscle contraction.

Motor unit firing rates and contractile properties in tibialis anterior of young and old men

The effects of aging on motoneuron firing rates and muscle contractile properties were studied in tibialis anterior muscle by comparing results from six young (20.8 +/- 0.8 yr) and six old men (82.0 +/- 1.7 yr). For each subject, data were collected from repeated tests over a 2-wk period. Contractile tests included maximal voluntary contraction (MVC) with twitch interpolation and stimulated twitch contractions. The old men had 26% lower MVC torque (P < 0.01) than did the young men, but percent activation was not different (99.1 and 99.3%, respectively). Twitch contraction durations were 23% longer (P < 0.01) in the old compared with the young men. During a series of repeated brief steady-state contractions at 10, 25, 50, 75, and 100% MVC, motor unit firing rates were recorded. Results from approximately 950 motor unit trains in each subject group indicated that at all relative torque levels mean firing rates were 30-35% lower (P < 0.01) in the old subjects. Comparisons between young and old subjects' mean firing rates at each of 10%, 50%, and MVC torques and their corresponding mean twitch contraction duration yielded a range of moderate-to-high correlations (r = -0.67 to -0.84). That lower firing rates were matched to longer twitch contraction durations in the muscle of old men, and relatively higher firing rates were matched with shorter contraction times from the young men, indirectly supports the neuromuscular age-related remodeling principle.

Quadriceps muscle strength, contractile properties, and motor unit firing rates in young and old men

Changes with age in the voluntary static and dynamic strength of the quadriceps muscle group have been well characterized, and the importance of the muscle group for locomotion and independent living have been highlighted in both normal human aging and in clinical studies. Surprisingly few studies of this muscle group have described age-related changes in voluntary activation ability using twitch interpolation and changes in stimulated contractile properties, and none have assessed the influence of old age on motor unit firing rates. We compared in 13 young (mean age 26 years) and 12 old (mean age 80 years) men the voluntary isometric strength, stimulated contractile properties, and average steady state motor unit firing rates in the quadriceps muscle. Maximum voluntary contraction (MVC) force and twitch tension were approximately 50% lower in the old men, but contractile speed was only approximately 10% slower than in the young men. There was no difference in the ability of either group to activate the quadriceps to a high degree (94-96%). At all isometric force levels tested (10%, 25%, 50%, 75%, and 100% MVC), there were no differences in mean motor unit firing rates. In both groups, the range of firing rates was similar and not large ( approximately 8 Hz at 10% MVC and 26 Hz at MVC). Thus, the substantial age-related weakness in this muscle does not seem to be related to changes in neural drive.

Effects of detraining on knee extensor strength and functional mobility in a group of elderly women

Long-term detraining results for individuals 75 years and older are needed. The purpose of this study was to assess long-term detraining effects on quadriceps strength and functional mobility in nursing home residents. Ten women (X = 82.8 years) who completed a strength training program were reassessed 1 year later. Clinical methods were used to remeasure dynamic and isometric quadriceps strength and functional mobility. One repetition maximum quadriceps strength declined 68.3% (p < 0.05) from trained values. Isometric strength losses were 29.8% at 90 degrees (p < 0.05), 28.7% at 60 degrees (p < 0.05), and 24.4% at 20 degrees (p < 0.05) of knee flexion 1 year postexercise. Fast-paced walking, self-selected paced walking, and timed up and go speed decreased 28.6% (p < 0.05), 19.5% (p < 0.05), and 54.1% (not significant), respectively, from posttraining. One year vs. baseline, isometric strength decreased 0-14.3%, dynamic strength decreased 48.9%, and functional mobility declined 16.5-20.7% despite an intervening training program. An increased strength loss rate beyond the age of 80 years may be a major factor influencing functional independence.

Reduced insulin binding to liver plasma membranes in inherently obese diabetic CBA/Ca mice

Insulin binding to isolated liver plasma membranes was measured in mice from C57BL and LACG strains, and in normal and obese diabetic mice from the Bristol CBA/Ca colony. A simple and rapid three-step method for the preparation and purification of liver plasma membranes, using Percoll density gradient centrifugation was used. Both high and low affinity binding was detected in membranes from all four groups of mice. The Kd values for binding were similar in all groups, but the insulin binding capacity (Bmax) at low and high affinity was significantly reduced in obese CBA mice compared to age-matched lean controls. It is proposed that insulin receptor down-regulation may account for the insulin resistance observed in spontaneously obese diabetic CBA mice.