Reliability of graded exercise testing after traumatic brain injury: submaximal and peak responses

Cardiorespiratory fitness assessment and training in the early sub-acute phase of recovery following traumatic brain injury: a systematic review

OBJECTIVES

To examine the safety of cardiorespiratory fitness (CRF) assessment and training in the early sub-acute phase of recovery (≤3 months) following moderate-to-extremely severe traumatic brain injury (TBI).

METHODS

A systematic review was completed in accordance with the PRISMA guidelines. Studies investigating adults and adolescents ≥15 years with moderate-to-extremely severe TBI were considered for inclusion. The methodological quality of the included studies was evaluated according to the McMaster Guidelines for Critical Review Form - Quantitative Studies.

RESULTS

Eleven studies with a total of 380 participants were included in the review. Adverse events (AEs) and symptom monitoring were poorly reported. Only four studies reported on the occurrence of AEs, with a total of eight AEs reported. Three of the reported AEs were concussion-like symptoms with no further exercise-induced symptom exacerbation reported. No serious AEs were reported.

CONCLUSION

There is no evidence to suggest that CRF assessment and training is unsafe in the early sub-acute phase of recovery following moderate-to-extremely severe TBI. However, despite the low AE and symptom exacerbation rates identified, a timeframe for safe commencement was unable to be established due to poor reporting and/or monitoring of exercise-induced symptoms and AEs in the current literature.

Measuring True Change in Individual Patients: Reliable Change Indices of Cardiac Rehabilitation Outcomes, and Implications for Quality Indicators

BACKGROUND

Mediated by outcomes such as improved exercise capacity, cardiac rehabilitation (CR) reduces morbidity and mortality. For accuracy, an individual CR patient's change must be measured reliably, an issue not typically considered in practice. Drawing from psychometric theory, we calculated reliable change indices (RCIs), to measure individual CR patients' true clinical change, apart from that from error and test practice/exposure, in exercise capacity, anxiety, and depression.

METHODS

Indirectly calculated exercise capacity (peak metabolic equivalents [METs]) and psychological symptoms were each measured twice, 1 week apart, by administering treadmill tests or the Hospital Anxiety and Depression Scale (HADS) to separate samples of 35 (mean age: 59.0 years; 6 women) and 96 (mean age: 64.4 years; 32 women) CR patients, respectively. Using test-retest reliability and mean difference scores from these samples to estimate error and practice/exposure effects, we calculated RCIs for a separate cohort (n = 2066; mean age: 62.0 years; 533 women) who completed 6-month CR, and compared change distributions (worsened/unchanged/improved) based on critical RCIs, mean and percent changes, cut-off scores, and standard deviations.

RESULTS

Practice/exposure effects were nonsignificant, except the mean HADS anxiety score decreased significantly (P ≤ 0.013; d = 0.17, small effect). Test-retest reliabilities were high (METs r = 0.934; HADS anxiety score r = 0.912; HADS depression score r = 0.90; P < 0.001). Among 2066 CR patients, RCI distributions differed (P < 0.001) from those of most other change criteria.

CONCLUSIONS

Change ascertainment depends on criterion choice. A Canadian Cardiovascular Society CR quality indicator of increase by 0.5 MET may be too small to assess individuals' functional capacity change. RCIs offer a pragmatic approach to benchmarking reliable change frequency, and pending further validation, could be used for feedback to individual patients.

Reliability of a recumbent stepper submaximal exercise test after traumatic brain injury

Purpose: To determine the test-retest reliability of a total body recumbent stepper (TBRS) submaximal exercise test and to examine its relationship with other measures throughout the International Classification of Functioning that are indicative of overall health in individuals with traumatic brain injury (TBI).Methods: Twenty-three ambulatory individuals with severe, chronic (>6 mos) TBI completed a TBRS submaximal exercise test, 6-minute walk test (6MWT), and Mayo Portland Adaptability Inventory (MPAI-4) at initial testing. A repeat TBRS submaximal exercise test was conducted 4-7 days later. Estimated peak oxygen consumption (VO₂) was calculated from the TBRS submaximal exercise test using the VO₂ prediction equation. Average daily step count was collected by an activity monitor for the 4-7-day period between tests.Results: Test-retest reliability was good (ICC_3,1 = 0.79, p < .001). The difference between the tests was 0.46 ml・kg^-1・min^-1 which was not statistically different. Neither the 6MWT distance nor gait speed are related to the TBRS-estimated peak VO₂. The MPAI-4 total score and adjustment subscale each had a fair relationship with the TBRS-estimated peak VO₂ (r = -0.41, p = .05; rs = -0.41, p = .05, respectively).Conclusion: These data suggest that the TBRS submaximal exercise test may be a reliable measure to estimate peak VO₂ in ambulatory adults with chronic severe TBI.

Physical Activity Intolerance and Cardiorespiratory Dysfunction in Patients with Moderate-to-Severe Traumatic Brain Injury

Moderate-to-severe traumatic brain injury (TBI) is a chronic health condition with multi-systemic effects. Survivors face significant long-term functional limitations, including physical activity intolerance and disordered sleep. Persistent cardiorespiratory dysfunction is a potentially modifiable yet often overlooked major contributor to the alarmingly high long-term morbidity and mortality rates in these patients. This narrative review was developed through systematic and non-systematic searches for research relating cardiorespiratory function to moderate-to-severe TBI. The literature reveals patients who have survived moderate-to-severe TBI have ~ 25-35% reduction in maximal aerobic capacity 6-18 months post-injury, resting pulmonary capacity parameters that are reduced 25-40% for weeks to years post-injury, increased sedentary behavior, and elevated risk of cardiorespiratory-related morbidity and mortality. Synthesis of data from other patient populations reveals that cardiorespiratory dysfunction is likely a consequence of ventilator-induced diaphragmatic dysfunction (VIDD), which is not currently addressed in TBI management. Thus, cardiopulmonary exercise testing should be routinely performed in this patient population and those with cardiorespiratory deficits should be further evaluated for diaphragmatic dysfunction. Lack of targeted treatment for underlying cardiorespiratory dysfunction, including VIDD, likely contributes to physical activity intolerance and poor functional outcomes in these patients. Interventional studies have demonstrated that short-term exercise training programs are effective in patients with moderate-to-severe TBI, though improvement is variable. Inspiratory muscle training is beneficial in other patient populations with diaphragmatic dysfunction, and may be valuable for patients with TBI who have been mechanically ventilated. Thus, clinicians with expertise in cardiorespiratory fitness assessment and exercise training interventions should be included in patient management for individuals with moderate-to-severe TBI.

Fitness training for cardiorespiratory conditioning after traumatic brain injury

BACKGROUND

Reduced cardiorespiratory fitness (cardiorespiratory deconditioning) is a common consequence of traumatic brain injury (TBI). Fitness training may be implemented to address this impairment.

OBJECTIVES

The primary objective of this updated review was to evaluate whether fitness training improves cardiorespiratory fitness in people who have sustained a TBI. The secondary objectives were to evaluate whether fitness training improves body function and structure (physical and cognitive impairments, psychological responses resulting from the injury), activity limitations and participation restrictions in people who have sustained a TBI as well as to evaluate its safety, acceptance, feasibility and suitability.

SEARCH METHODS

We searched 10 electronic databases (the Cochrane Injuries Group Trials Register; the Cochrane Central Register of Controlled Trials (CENTRAL); Embase; PubMed (MEDLINE); CINAHL; AMED; SPORTDiscus; PsycINFO; PEDro and PsycBITE) and the International Clinical Trials Registry Platform for relevant trials. In addition we screened reference lists from systematic reviews related to the topic that we identified from our search, and from the included studies, and contacted trialists to identify further studies. The search was run in August 2017.

SELECTION CRITERIA

Randomised controlled studies with TBI participants were eligible if they compared an exercise programme incorporating cardiorespiratory fitness training to usual care, a non-exercise intervention, or no intervention.

DATA COLLECTION AND ANALYSIS

Two authors independently screened the search results, extracted data and assessed bias. We contacted all trialists for additional information. We calculated mean difference (MD) or standardised mean difference (SMD) and 95% confidence intervals (CI) for continuous data, and odds ratio with 95% CI for dichotomous data. We pooled data when there were sufficient studies with homogeneity.

MAIN RESULTS

Two new studies incorporating 96 participants were identified in this update and were added to the six previously included studies. A total of eight studies incorporating 399 participants are included in the updated review. The participants were primarily men aged in their mid-thirties who had sustained a severe TBI. No studies included children. The studies were clinically diverse with regard to the interventions, time postinjury and the outcome measures used. At the end of intervention, the mean difference in peak power output was 35.47 watts (W) in favour of fitness training (MD 35.47 W, 95% CI 2.53 to 68.41 W; 3 studies, 67 participants; low-quality evidence). The CIs include both a possible clinically important effect and a possible negligible effect, and there was moderate heterogeneity among the studies.Five of the secondary outcomes had sufficient data at the end of intervention to enable meta-analysis: body composition (SMD 0.29 standard deviations (favouring control), 95% CI -0.22 to 0.79; 2 studies, 61 participants; low-quality evidence), strength (SMD -0.02 (favouring control), 95% CI -0.86 to 0.83; 2 studies, 23 participants; very low-quality evidence), fatigue (SMD -0.32 (favouring fitness training), 95% CI -0.90 to 0.26; 3 studies, 130 participants; very low-quality evidence), depression (SMD -0.43 (favouring fitness training), 95% CI -0.92 to 0.06; 4 studies, 220 participants; very low-quality evidence), and neuromotor function (MD 0.01 m (favouring fitness training), 95% CI -0.25 to 0.27; 2 studies, 109 participants; moderate-quality evidence). It was uncertain whether fitness training was more or less effective at improving these secondary outcomes compared to the control interventions. Quality of life was assessed in three trials, but we did not pool the data because of substantial heterogeneity. Five of the eight included studies had no dropouts from their intervention group and no adverse events were reported in any study.

AUTHORS' CONCLUSIONS

There is low-quality evidence that fitness training is effective at improving cardiorespiratory deconditioning after TBI; there is insufficient evidence to draw any definitive conclusions about the other outcomes. Whilst the intervention appears to be accepted by people with TBI, and there is no evidence of harm, more adequately powered and well-designed studies are required to determine a more precise estimate of the effect on cardiorespiratory fitness, as well as the effects across a range of important outcome measures and in people with different characteristics (e.g. children). In the absence of high quality evidence, clinicians may be guided by pre-exercise screening checklists to ensure the person with traumatic brain injury is safe to exercise, and set training parameters using guidelines established by the American College of Sports Medicine for people who have suffered a brain injury.

Graded Aerobic Treadmill Testing in Adolescent Traumatic Brain Injury Patients

PURPOSE

To examine the safety and tolerability of clinical graded aerobic treadmill testing in recovering adolescent moderate and severe traumatic brain injury (TBI) patients referred to a multidisciplinary pediatric concussion program.

METHODS

We completed a retrospective case series of two moderate and five severe TBI patients (mean age, 17.3 years) who underwent initial Buffalo Concussion Treadmill Testing at a mean time of 71.6 days (range, 55-87) postinjury.

RESULTS

Six patients completed one graded aerobic treadmill test each and one patient underwent initial and repeat testing. There were no complications. Five initial treadmill tests were completely tolerated and allowed an accurate assessment of exercise tolerance. Two initial tests were terminated early by the treatment team because of neurological and cardiorespiratory limitations. As a result of testing, two patients were cleared for aerobic exercise as tolerated and four patients were treated with individually tailored submaximal aerobic exercise programs resulting in subjective improvement in residual symptoms and/or exercise tolerance. Repeat treadmill testing in one patient performed after 1 month of treatment with submaximal aerobic exercise prescription was suggestive of improved exercise tolerance. One patient was able to tolerate aerobic exercise following surgery for posterior glottic stenosis.

CONCLUSIONS

Preliminary results suggest that graded aerobic treadmill testing is a safe, well tolerated, and clinically useful tool to assess exercise tolerance in appropriately selected adolescent patients with TBI. Future prospective studies are needed to evaluate the effect of tailored submaximal aerobic exercise prescription on exercise tolerance and patient outcomes in recovering adolescent moderate and severe TBI patients.

Functional Changes after Recombinant Human Growth Hormone Replacement in Patients with Chronic Traumatic Brain Injury and Abnormal Growth Hormone Secretion

We explored the effects of recombinant human growth hormone (rhGH) replacement on physical and cognitive functioning in subjects with a moderate-to-severe traumatic brain injury (TBI) with abnormal growth hormone (GH) secretion. Fifteen individuals who sustained a TBI at least 12 months prior to study enrollment were identified as having abnormal GH secretion by glucagon stimulation testing (maximum GH response less than 8 ng/mL). Peak cardiorespiratory capacity, body composition, and muscle force testing were assessed at baseline and one year after rhGH replacement. Additionally, standardized neuropsychological tests that assess memory, processing speed, and cognitive flexibility, as well as self-report inventories related to depression and fatigue, were administered at baseline and 1 year after rhGH replacement. Comparison tests were performed with proper post hoc analyses. All analyses were carried out at α < 0.05. Peak O₂ consumption, peak oxygen pulse (estimate of cardiac stroke volume), and peak ventilation all significantly increased (p < 0.05). Maximal isometric and isokinetic force production were not altered. Skeletal muscle fatigue did not change but the perceptual rating of fatigue was reduced by ∼25% (p = 0.06). Cognitive performance did not change significantly over time, whereas self-reported symptoms related to depression and fatigue significantly improved. The observed changes suggest that rhGH replacement has a positive impact on cardiorespiratory fitness and a positive impact on perceptual fatigue in survivors of TBI with altered GH secretion.

The Aetiology of Reduced Cardiorespiratory Fitness Among Adults with Severe Traumatic Brain Injury and the Relationship with Physical Activity: A Narrative Review

Reduced cardiorespiratory fitness or cardiorespiratory deconditioning is a secondary physical impairment commonly reported to affect people after traumatic brain injury (TBI), both in the short- and long-term. Eleven studies have measured peak oxygen uptake${\rm ({\dot V}O}_{{\rm 2peak}} )$to evaluate fitness in this population. The mean (SD)${\rm \dot VO}_{{\rm 2peak}}$from these studies was 27.2 (6.7) mL.kg−1·min−1, which is markedly below the average fitness level of age-matched healthy individuals. The aetiology of cardiorespiratory deconditioning has not been well evaluated among people with TBI; however, studies on prolonged bed rest and studies on the acute consequences of TBI inform our current understanding. The primary aim of this paper is to present a model to describe the physiological factors contributing to the development of cardiorespiratory deconditioning among people with severe TBI. We propose that both central and peripheral factors contribute to reduced fitness, and that these changes occur because of both the initial brain damage and trauma sustained and the prolonged and initially extreme physical inactivity that is commonly experienced after this type of injury. Reduced fitness can significantly affect the ability to return to pre-injury activities. Given that reintegration into the community is a key goal of rehabilitation among people with TBI, interventions that can prevent or reverse reduced fitness need to be implemented.

Blunted IL-6 and IL-10 response to maximal aerobic exercise in patients with traumatic brain injury

INTRODUCTION

In healthy individuals, strenuous exercise typically results in a transient increase in the inflammatory cytokine, interleukin-6 (IL-6). This increase in IL-6 is reported to have pleiotropic effects including increased glucose uptake, increased fat oxidation, and anti-inflammatory actions.

PURPOSE

The purpose of this study was to determine if patients with a traumatic brain injury (TBI) have a differential cytokine response to exercise compared to healthy control subjects (CON).

METHODS

Eight patients with a TBI and eight age- and sex-matched controls completed an exercise test to volitional exhaustion. Metabolic data were collected continuously, and blood was collected at baseline, immediately post-exercise, and every 10 min for an hour post-exercise. Serum was analyzed for IL-6, tumor necrosis factor-alpha, interleukin-10 (IL-10), and cortisol.

RESULTS

Peak oxygen consumption (CON 33 ± 2 ml kg(-1) min(-1); TBI 29 ± 2 ml kg(-1) min(-1)) and respiratory exchange ratio during exercise were equivalent between groups. There were no baseline differences between groups for cytokine or cortisol concentrations. Exercise did not increase IL-6 in TBI, whereas IL-6 was elevated from baseline in CON at 0, 40, and 50 min post-exercise (p < 0.05). IL-10 and cortisol increased from baseline in CON at 40 min post-exercise (p < 0.05).

CONCLUSIONS

These data indicate that patients recovering from TBI have blunted IL-6, IL-10, and cortisol responses following a peak exercise test compared to non-TBI controls. This lack of an exercise response may represent impaired hypothalamic-pituitary-adrenal axis function.

Ventilatory anaerobic thresholds of individuals recovering from traumatic brain injury compared with noninjured controls

OBJECTIVE

The purpose of this study was to compare the peak aerobic capacities and ventilatory anaerobic thresholds (VAT) of individuals with a traumatic brain injury (TBI) to age- and gender-matched controls.

METHODS

Nineteen participants that previously suffered a mild to moderate TBI and 19 apparently healthy controls volunteered as subjects. Traumatic brain injury and healthy controls were matched for age and gender and were similar in weight and body mass index. Volunteers performed a maximal graded treadmill test to volitional failure where oxygen consumption ((Equation is included in full-text article.)O2), carbon dioxide production ((Equation is included in full-text article.)CO2, ventilation ((Equation is included in full-text article.)E, and heart rate were measured continuously. From metabolic and ventilatory data, VAT was measured using a previously described method. VAT and peak exercise responses of participants with a TBI were compared with healthy controls.

RESULTS

The (Equation is included in full-text article.)O2, and (Equation is included in full-text article.)CO2 at VAT and peak exercise were lower for TBI compared with healthy controls. (Equation is included in full-text article.)E was also lower for TBI at VAT and peak exercise. Heart rate was lower for TBI at VAT; however, TBI had similar heart rate to healthy controls at peak exercise.

CONCLUSIONS

The VAT and peak exercise capacities of participants with a TBI were below the metabolic demands of many routine daily activities. The data suggest that therapeutic interventions for individuals with a TBI should include targeted exercise prescriptions to improve cardiorespiratory fitness.

Responsiveness and validity of the six-minute walk test in individuals with traumatic brain injury

BACKGROUND

A simple test of aerobic fitness for patients with traumatic brain injury (TBI) that is valid, reliable, and responsive to change is needed to provide clinicians a functional measure of cardiorespiratory capacity.

OBJECTIVE

The purpose of this study was to examine the validity and responsiveness to change of the Six-Minute Walk Test (6MWT) in individuals with TBI.

DESIGN

A cohort, pretest-posttest, comparison study was conducted.

METHODS

Twenty-one patients performed the 6MWT upon admission to and prior to discharge from a postacute rehabilitation facility. Heart rate and distance traveled were recorded. A physiologic cost index (PCI) (beats per meter) was calculated based on steady-state heart rate. At discharge, all participants were able to perform a graded treadmill exercise test to exhaustion during which peak oxygen consumption (Vo(2)) was measured.

RESULTS

Between admission and discharge, mean total distance increased from 342.6 m (SD=127.0) to 408.9 m (SD=124.2), and work increased from 27,185 kg·m (SD=10,528) to 34,114 kg·m (SD=12,057). The effect size indexes were 1.10 and 1.12 for distance and work, respectively. Correlations (r) between the discharge peak Vo(2) and the discharge 6MWT distance, PCI, and work were .58, -.61, and .47, respectively.

LIMITATIONS

Stratification by gait speed may have improved responsiveness, especially for the slow ambulators.

CONCLUSIONS

All measures correlated well with peak Vo(2), establishing an acceptable level of criterion-related (concurrent) validity. The addition of heart rate and calculating the PCI was only slightly better at predicting peak Vo(2), albeit nonsignificant, than a simple measure of total distance. The 6MWT provides a good estimate of peak aerobic capacity, and some measures are more responsive to change than others in patients recovering from TBI.

What are critical outcome measures for patients receiving pituitary replacement following brain injury?

There are scant prospective studies defining improvements in critical outcome measures with hormone replacement in hypopituitarism secondary to brain injury. We review the tests of cognition and physical function and summarize their use for subjects that are deficient in anterior hormone production during anterior pituitary hormone replacement in brain injury and propose these as the minimal tests that are feasible for a physician to perform in a clinical setting. We summarize the studies conducted to assess outcome measures after brain injury and also report preliminary findings for improvements in cognition and physical function in subjects with brain injury and GH deficiency.

Reliability of peak treadmill exercise tests in mild Alzheimer disease

INTRODUCTION

The purpose of this study was to determine the reliability of treadmill peak exercise testing in people with very mild-to-mild Alzheimer disease (AD).

METHODS

Sixteen subjects with very mild-to-mild AD performed graded peak treadmill exercise tests twice within a 14-day period. Heart rate, oxygen consumption, and respiratory exchange ratio (RER) were continuously monitored. Peak values were analyzed for absolute level of agreement.

RESULTS

Fourteen participants (87.5%) completed testing. Reliability was excellent with total peak oxygen consumption (VO2peak) (ml/kg/min) highly correlated across the two tests (r = 0.94, p < .001) with an intraclass correlation coefficient (ICC[3,1]) of 0.92 (95% confidence interval (CI) = 0.78, 0.97). The standard error of measurement (SEM) for VO2peak was 1.29 (95% CI = 0.88, 1.89).

CONCLUSIONS

These results indicate that peak exercise testing on a treadmill is reliable in the early stages of AD.

Physical therapy recommendations for service members with mild traumatic brain injury

Mild traumatic brain injuries (MTBIs) are of increasing concern in both the military and civilian populations as the potential long-term effects and costs of such injuries are being further recognized. Injuries from conflicts in Afghanistan and Iraq have increased public awareness and concern for TBI. The Proponency Office for Rehabilitation and Reintegration, Office of the Surgeon General, US Army tasked a team of physical and occupational therapists to assemble evidence-informed guidelines for assessment and intervention specific to MTBI. Given the paucity of specific guidelines for physical therapy related to MTBI, we focused on literature that dealt with the specific problem area or complaint of the Service member following MTBI. Recommendations, characterized as practice standards or practice options based on strength of evidence, are provided relative to patient/client education, activity intolerance, vestibular dysfunction, high-level balance dysfunction, posttraumatic headache, temporomandibular disorder, attention and dual-task performance deficits, and participation in exercise. While highlighting the need for additional research, this work can be considered a starting point and impetus for the development of evidence-based practice in physical therapy for our deserving Service members.

Endurance training and cardiorespiratory conditioning after traumatic brain injury

OBJECTIVE

To examine the importance of cardiorespiratory conditioning after traumatic brain injury (TBI) and provide recommendations for patients recovering from TBI.

METHOD

Review of literature assessing the effectiveness of endurance training programs.

MAIN OUTCOMES AND RESULTS

A sedentary lifestyle and lack of endurance are common characteristics of individuals with TBI who have a reduction in peak aerobic capacity of 25% to 30% compared with healthy sedentary persons. Increased physical activity and exercise training improves cardiorespiratory fitness in many populations with physical and cognitive impairments. Therefore, increasing the endurance and cardiorespiratory fitness of persons with TBI would seem to have important health implications. However, review of the TBI literature reveals that there have been few well-designed, well-controlled studies of physiologic and psychological adaptations of fitness training. Also lacking are long-term follow-up studies of persons with TBI.

CONCLUSIONS

Assessing endurance capacity and cardiorespiratory fitness early in the TBI rehabilitation process merits consideration as a standard of care by professional rehabilitation societies. Also, providing effective, safe, and accessible training modalities would seem to be an important consideration for persons with TBI, given the mobility impairments many possess. Long-term follow-up studies are needed to assess the effectiveness of cardiorespiratory training programs on overall morbidity and mortality.

Cardiorespiratory fitness and preserved medial temporal lobe volume in Alzheimer disease

Exercise and cardiorespiratory (CR) fitness may moderate age-related regional brain changes in nondemented (ND) older adults. The relationship of fitness to Alzheimer disease (AD)-related brain change is understudied, particularly in the hippocampus, which is disproportionately affected in early AD. The role of apolipoprotein E4 (apoE4) genotype in modulating this relationship is also unknown. ND (n=56) and early-stage AD patients (n=61) over the age of 65 years had magnetic resonance imaging and CR fitness assessments. Voxel-based morphometry techniques were used to identify AD-related atrophy. We analyzed the relationship of CR fitness with white and gray matter within groups, assessed fitness-related brain volume change in areas most affected by AD-related atrophy, and then analyzed differential fitness-brain relationships between apoE4 carriers. Atrophy was present in the medial temporal, temporal, and parietal cortices in patients with mild AD. There was a significant positive correlation of CR fitness with parietal and medial temporal volume in AD patients. ND patients did not have a significant relationship between brain volume and CR fitness in the global or small volume correction analyses. There was not a significant interaction for fitness x apoE4 genotype in either group. In early-stage AD, CR fitness is associated with regional brain volumes in the medial-temporal and parietal cortices suggesting that maintaining CR fitness may modify AD-related brain atrophy.

Validity of the modified 20-metre shuttle test: Assessment of cardiorespiratory fitness in people who have sustained a traumatic brain injury

PRIMARY OBJECTIVE

To validate the modified 20-metre shuttle test in adults who have sustained a traumatic brain injury (TBI).

DESIGN

Single-sample validity study.

SETTING

Brain injury rehabilitation unit.

PARTICIPANTS

Twenty-four adults with severe TBI, discharged from hospital for at least 6-months.

PROTOCOL

Participants attended the facility for a familiarization session, followed by a symptom-limited treadmill test and a modified shuttle test on two separate days. The treadmill test was based on an individualised protocol which used a physiotherapist-selected speed and increments in gradient every minute until volitional fatigue. The modified shuttle test was externally-paced and commenced with a speed of 2.4 km h(-1) which increased every minute until volitional fatigue.

MAIN MEASURES

Four primary measures were taken from both tests: peak oxygen uptake, peak heart rate, maximal velocity and rating of perceived exertion.

RESULTS

All participants completed the study. There were no adverse events. A high correlation was observed between the modified shuttle test and the treadmill test for peak oxygen uptake, peak heart rate and maximal velocity (r = 0.96, r = 0.80, r = 0.82, respectively; p < 0.001), but not for rating of perceived exertion (r = 0.013, p = 0.952).

CONCLUSION

The modified shuttle test is a valid measure of cardiorespiratory fitness in people who have sustained a TBI.

Aerobic capacity and growth hormone deficiency after traumatic brain injury

CONTEXT

GH deficiency occurs in approximately 20% of all individuals who suffer from a moderate to severe traumatic brain injury.

OBJECTIVE

This study determined whether GH deficiency secondary to traumatic brain injury had an effect on aerobic capacity.

DESIGN

Subjects were screened for GH deficiency by the glucagon stimulation test and performed a maximal treadmill exercise test.

SETTING

Patients were studied in the postacute recovery phase after traumatic brain injury.

PARTICIPANTS

Thirty-five individuals were studied. Groups were formed as follows: normal GH axis, greater than 8 ng/ml response (n = 12); insufficient, GH 3-8 ng/ml response (n = 11); and deficient, less than 3 ng/ml response (n = 12).

INTERVENTION

There was no intervention.

MAIN OUTCOME MEASURE

Aerobic capacity was assessed by measuring expired gases during a graded treadmill exercise test. One-way and two-way ANOVAs were carried out on all peak and submaximal cardiorespiratory variables, respectively. Appropriate post hoc comparisons followed as necessary.

RESULTS

Significantly higher peak oxygen consumption was found in traumatic brain injury subjects with GH normal vs. GH insufficient and deficient [26.4 +/- 6.9, 20.8 +/- 4.6, and 19.7 +/- 5.0, respectively (P < 0.05)]. Submaximal oxygen consumption was significantly higher in the GH normal group. All other variables were statistically similar.

CONCLUSIONS

This study shows that individuals with traumatic brain injury with normal GH secretion have below normal aerobic capacity and those patients who have GH insufficiency/deficiency are further deconditioned. Studies of GH replacement in these subjects should be conducted to assess whether GH therapy can improve cardiorespiratory fitness and prevent secondary disability.

Cardiorespiratory fitness in early-stage Alzheimer disease

There is an increasing interest in exercise and fitness in Alzheimer disease (AD) given evidence suggesting a role in the maintenance of cognitive health. There is, however, little data on the objective measure of cardiorespiratory fitness in individuals with AD. Thus, we assessed cardiorespiratory fitness in early AD and its relationship with physical activity levels, health markers, and cognitive performance in nondemented (Clinical Dementia Rating 0, n=31) and early-stage AD (Clinical Dementia Rating 0.5 and 1, n=31) participants. Cardiorespiratory fitness was assessed with maximal exercise testing to determine peak oxygen consumption (VOpeak2). Additionally, dual emission x-ray absorptiometry scanning for body composition and glucose tolerance tests were conducted. Despite reductions in physical performance and habitual physical activity levels in early AD, cardiorespiratory fitness (VOpeak2) was comparable in the 2 groups (19.8 in early AD vs. 21.2 mL/kg/min in nondemented, P=0.26). AD participants performed well on treadmill tests with similar levels of perceived exertion, maximal heart rate, and respiratory exchange ratio compared with nondemented individuals. After controlling for age and sex, VOpeak2 was associated with a beneficial glucoregulatory profile and inversely associated with percent body fat, body mass index, and triglycerides. A relationship between cognitive performance measures and VOpeak2 was not apparent. These results suggest that individuals in the early stages of AD have the capacity for maximal exercise testing and have comparable levels of cardiorespiratory fitness as nondemented individuals. Reduced physical activity associated with early AD underscores the need for further defining the role of exercise as a potential therapeutic intervention in the early stages of AD.

Fitness training for cardiorespiratory conditioning after traumatic brain injury

BACKGROUND

Cardiorespiratory deconditioning is a common sequelae after traumatic brain injury (TBI). Clinically, fitness training is implemented to address this impairment, however this intervention has not been subject to rigorous review.

OBJECTIVES

The primary objective was to evaluate whether fitness training improves cardiorespiratory fitness in people who have sustained a TBI.

SEARCH STRATEGY

We searched ten electronic databases (Cochrane Injuries Group Trials Register; Cochrane Central Register of Controlled Trials (CENTRAL); EMBASE; PubMed (MEDLINE); CINAHL; AMED; SPORTDiscus; PsycINFO; PEDro and PsycBITE) and two clinical trials registers (TrialsCentral and Current Controlled Trials). The last search was August 2007. In addition we screened reference lists from included studies and contacted trialists to identify further studies.

SELECTION CRITERIA

Randomised controlled studies with TBI participants were eligible if they compared an exercise programme incorporating cardiorespiratory fitness training to usual care, a non-exercise intervention or no intervention.

DATA COLLECTION AND ANALYSIS

Two authors independently screened the search output, extracted data and assessed quality. All trialists were contacted for additional information. Mean difference and 95% confidence intervals (CI) were calculated for continuous data and risk difference or odds ratio and 95% CI were calculated for dichotomous data. Data were pooled when there were sufficient studies with clinical and statistical homogeneity.

MAIN RESULTS

Six studies, incorporating 303 participants, were included. The participants were primarily males, in their mid thirties who had sustained a severe TBI. The studies were clinically diverse with regard to the interventions, time post-injury and the outcome measures used; therefore, the primary outcome could not be pooled. Three of the six studies indirectly assessed change in cardiorespiratory fitness after fitness training using the peak power output obtained during cycle ergometry (either at volitional fatigue or at a predetermined endpoint, that is, a percentage of predicted heart rate maximum). Cardiorespiratory fitness was improved after fitness training in one study (mean difference 59 watts, 95% CI 24 to 94), whilst there was no significant improvement in the other two studies. Four of the six studies had no drop-outs from their intervention group and no adverse events were reported in any study.

AUTHORS' CONCLUSIONS

There is insufficient evidence to draw any definitive conclusions about the effects of fitness training on cardiorespiratory fitness. Whilst it appears to be a safe and accepted intervention for people with TBI, more adequately powered and well-designed studies are required to determine the effects across a range of outcome measures.

Cardiorespiratory capacity after weight-supported treadmill training in patients with traumatic brain injury

BACKGROUND AND PURPOSE

The primary goal of body-weight-supported treadmill training (BWSTT) has been to improve the temporal and spatial characteristics of unsupported overground walking; however, little attention has been given to cardiorespiratory adaptations. The purpose of this case report is to describe the effects of BWSTT on cardiorespiratory fitness in 2 patients recovering from severe traumatic brain injury (TBI).

CASE DESCRIPTION

Both patients were involved in motor vehicle accidents and were studied after admission to a postacute residential treatment program. Patient 1 was a 25-year-old man (initial Glasgow Coma Scale [GCS] score=3) who began observation and treatment 3 months after the injury. Patient 2 was an 18-year-old woman (initial GCS=6) who began observation and treatment 1 year after the injury.

OUTCOMES

Each patient received 2 to 3 sessions of BWSTT per week. Aerobic capacity was measured while they ambulated on a treadmill without body-weight support before and after BWSTT. Both patients' submaximal and peak responses improved. For patient 1 and patient 2, total treadmill work performed increased 134% and 53%, respectively. Peak oxygen uptake increased 24% for patient 1 and 16% for patient 2. Estimated cardiac stroke volume (oxygen pulse) increased 32% and 26% for patient 1 and patient 2, respectively.

DISCUSSION

The observations made on these 2 patients suggest that BWSTT has the potential to favorably change cardiorespiratory capacity after TBI.

Aerobic capacity after traumatic brain injury: comparison with a nondisabled cohort

OBJECTIVE

To compare aerobic capacity of people recovering from traumatic brain injury (TBI) with an age- and sex-matched group of nondisabled sedentary people.

DESIGN

Descriptive comparative study of peak and submaximal physiologic responses.

SETTING

Residential postacute treatment center.

PARTICIPANTS

Convenience sample of 13 people with TBI and 13 age- and sex-matched nondisabled subjects. All subjects could walk 5.3 kph (3.3 mph), follow 2-step commands, and comply with testing using the gas collection apparatus.

INTERVENTIONS

Not applicable.

MAIN OUTCOME MEASURES

Subjects performed a graded maximal treadmill test during which heart rate, minute ventilation (VE), oxygen consumption (VO2), carbon dioxide production, and respiratory exchange ratio (RER) were measured every minute until exhaustion. Ventilatory equivalents for oxygen (VE/VO2) and oxygen pulse were calculated.

RESULTS

Subjects recovering from TBI had significantly lower peak responses for heart rate, VO2, VE, and oxygen pulse TBI (P<.01). Peak RER and VE/VO2 were similar. There were significant differences in submaximal responses for VE/VO2 and oxygen pulse.

CONCLUSIONS

Patients with TBI were significantly more deconditioned than a comparable group of sedentary people without disability. Participation in cardiorespiratory fitness programs after TBI should be encouraged to prevent secondary disability.