Exercise Improves Cardiorespiratory Fitness, but Not Arterial Health, after Spinal Cord Injury: The CHOICES Trial.

Arterial stiffness, as measured by carotid-femoral pulse wave velocity (cfPWV), is elevated after spinal cord injury (SCI). In the uninjured population, exercise training has been shown to reduce arterial stiffness. In a randomized, multi-center clinical trial, we evaluated the impact of two exercise interventions on cardiovascular disease risk factors in persons with chronic SCI. A total of 46 adults with motor-complete SCI with neurological levels of injury between the fourth cervical and sixth thoracic spinal cord segments (C4-T6) were randomly assigned to either body-weight-supported treadmill training (BWSTT) or arm-cycle ergometer training (ACET). Participants trained 3 days per week for 24 weeks. Exercise session duration progressed gradually to reach 30 and 60 min for ACET and BWSTT, respectively. The primary outcome was arterial stiffness, assessed by cfPWV, and was measured at baseline, 12 weeks of training, and at 24 weeks. Secondary outcomes included cardiorespiratory fitness (CRF) and cardiometabolic health measures and were measured before and after completion of training. Fourteen participants per intervention arm completed the exercise intervention. Our results show no effect of either exercise intervention on arterial stiffness (p = 0.07) and cardiometabolic health measures (p > 0.36). However, peak oxygen uptake increased with ACET compared with BWSTT (p = 0.04). The findings of this trial demonstrate that although 24 weeks of upper-body exercise improved CRF in persons with motor-complete SCI ≥T6, neither intervention resulted in improvements in arterial stiffness or cardiometabolic health measures. ClinicalTrials.gov identifier: NCT01718977.

Viability of high intensity interval training in persons with spinal cord injury-a perspective review.

Spinal cord injury (SCI) leads to loss of sensory and motor function below the level of injury leading to paralysis and limitations to locomotion. Therefore, persons with SCI face various challenges in engaging in regular physical activity, which leads to a reduction in physical fitness, increases in body fat mass, and reduced physical and mental health status. Moderate intensity continuous training (MICT) is recommended to enhance physical fitness and overall health status in this population, but it is not always effective in promoting these benefits. High intensity interval training (HIIT) has been promoted as an alternative to MICT in individuals with SCI due to its documented efficacy in healthy able-bodied individuals as well as those with chronic disease. However, the body of knowledge concerning its application in this population is limited and mostly composed of studies with small and homogeneous samples. The aim of this review was to summarize the existing literature regarding the efficacy of HIIT on changes in health- and fitness-related outcomes in this population, denote potential adverse responses to HIIT, describe how participants perceive this modality of exercise training, and identify the overall feasibility of interval training in persons with SCI.

Locomotor training in people with spinal cord injury: is this exercise?

Locomotor training holds tremendous appeal to people with spinal cord injury who are wheelchair dependent, as the reacquisition of gait remains one of the most coveted goals in this population. For the last few decades this type of training has remained primarily in the clinical environment, as it requires the use of expensive treadmills with bodyweight support or complex overhead suspension tracks to facilitate overground walking. The development of powered exoskeletons has taken locomotor training out of the clinic, both improving accessibility and providing a potential option for community ambulation in people with lower limb paralysis. A question that has yet to be answered, however, is whether or not locomotor training offers a sufficiently intense stimulus to induce improvements in fitness or health. As inactivity-related secondary health complications are a major source of morbidity and mortality in people with SCI, it would be important to characterize the potential of locomotor training to not only improve functional walking ability, but also improve health-related fitness. This narrative review will summarize the key literature in this area to determine whether locomotor training challenges the cardiovascular, muscular or metabolic systems enough to be considered a viable form of exercise.

Benefits of Adhering to the Canadian Physical Activity Guidelines for Adults with Multiple Sclerosis Beyond Aerobic Fitness and Strength.

BACKGROUND: The Canadian Physical Activity Guidelines for Adults with Multiple Sclerosis (PAGs) were released in 2013 but have yet to be validated. We aimed to test the effectiveness of the PAGs in improving fitness, mobility, fatigue symptoms, and quality of life (QOL) in a large cohort of adults with multiple sclerosis (MS). METHODS: As part of an ongoing randomized controlled trial examining implementation of the PAGs, participants were randomized to either a direct referral group (physician referral to an exercise program following the PAGs; n = 42) or a control group (provided a print copy of the PAGs; n = 37). Physical activity behavior was assessed through weekly physical activity logs. Fitness, mobility, fatigue symptoms, and QOL were assessed at baseline and after 16 weeks. Participants were categorized as either PAG adherers (n = 30) or nonadherers (n = 49) to the PAGs based on achieving the weekly exercise recommendations at least 75% of the time. RESULTS: Adherence to the PAGs was twice as high in the referral group compared with the control group. Adherers experienced significantly greater improvements in peak oxygen consumption (29%), strength (7%-18%), mobility (16%), fatigue symptoms (-36%), and QOL (17%-22%) compared with nonadherers (P < .05). CONCLUSIONS: Following the PAGs for at least 12 of 16 weeks results in improvements in fitness, mobility, fatigue symptoms, and QOL, confirming their effectiveness for improving health in people with MS.

Sprint interval training versus moderate-intensity continuous training during inpatient rehabilitation after spinal cord injury: a randomized trial.

STUDY DESIGN: Randomized trial. OBJECTIVES: To evaluate the effectiveness of a 5-week sprint interval training (SIT) protocol on an arm-crank ergometer in individuals with sub-acute spinal cord injury (SCI). SETTING: Inpatient rehabilitation. METHODS: Individuals with SCI (N = 20; 9 tetraplegia/11 paraplegia; time since injury, 14-182 days; age, 46 ± 16 years; 15 M/5 F) were randomized to SIT or moderate-intensity continuous training (MICT). SIT consisted of 3 × 20 s. 'all-out' cycle sprints (≥100% peak power output) interspersed with 2 min of active recovery (10% peak power output; total time commitment, 10 mins). MICT involved 20 min of cycling (45% peak power output; total time commitment, 25 mins). Both training interventions were delivered 3 times/week for 5 weeks. Heart rate and Borg's Rating of Perceived Exertion (RPE; 6-20) were monitored throughout training sessions. Maximal and sub-maximal power outputs were assessed on an arm-crank ergometer. Exercise enjoyment, exercise self-efficacy, and pain were assessed at the end of the intervention. RESULTS: During training sessions, heart rate (135 bpm vs. 119 bpm; p = 0.05), peripheral RPE (16 vs. 12; p = 0.000), and central RPE (15 vs. 11; p = 0.004) responses were higher in the SIT group, yet total work performed was greater in MICT. Peak power output increased significantly with training (36%), with no difference between groups (39% vs. 33%; p = 0.524). Similarly, improvements in sub-maximal power output were not different across groups. There were no between-group differences in exercise enjoyment (p = 0.385), exercise self-efficacy (p = 0.930), or pain (p = 0780). CONCLUSIONS: Five weeks of SIT improved physical capacity to the same extent as MICT in individuals with sub-acute SCI, despite a significantly lower time commitment with SIT.

Physician referral improves adherence to the physical activity guidelines for adults with MS: A randomized controlled trial.

BACKGROUND: Commitment and adherence to community-based physical activity can be a challenge for clinical populations. The aim of this study was to explore the effectiveness of physician referral on adherence to the Physical Activity Guidelines (PAGs) for adults with MS. METHODS: Ninety-one participants with MS (age: 47.9 ±â€¯10.4 years, EDSS score: 3.5 ±â€¯1.8) were randomized into a direct referral to PAGs from a physician (REF) or control (CON) group (given a print copy of PAGs). After 16 weeks participants were categorized as either PAG "Adherers" (n = =30) or "Non-Adherers" (n = =49), based on achieving an adherence rate of ≥ 75%. RESULTS: Adherence to the PAGs was significantly higher in REF (68.0 ±â€¯28.6%) compared with CON (35.1 ±â€¯35.0%) (p < 0.05). There were no differences in EDSS scores, time since diagnosis, fitness, fatigue, mobility or QOL between those who adhered or did not adhere to the PAGs (p > 0.05), but greater self-efficacy for exercise at baseline was associated with higher adherence (p < 0.0001). INTERPRETATION: Direct referral to physical activity from a physician is twice as effective as simply providing information about physical activity for adherence to the PAG in people with MS. As physical activity is recognized as an effective therapeutic option for adults with MS it is important that physicians play a role in prescribing it to their patients. TRIAL REGISTRATION: ClinicalTrials.gov Identifier: NCT02100020.

Evaluation of the Keeogo™ Dermoskeleton.

Purpose: (1) To determine the specific functional characteristics of individuals with neurological impairments that may predict successful use of Keeogo™ dermoskeleton and (2) to quantify the specific benefit Keeogo™ provides to a regular user of the device. Methods: Thirteen individuals (seven males; six females; 52 ± 4.6 years old) with mobility impairments due to neurological disease or injury were recruited. Berg Balance Sale (BBS) score and Timed Up and Go (TUG) performance were used to identify baseline characteristics in participants. The 6-min walk test (6MWT) and 25-foot walk test (25FWT) were performed with the participants wearing and not wearing the dermoskeleton; a successful user of Keeogo™ displayed a ≥ 5% improvement in walking performance while wearing the device. A chronic stroke survivor (hemiparesis on left side) completed the stair climb test (SCT) and the 30-second chair stand test (30CST) with and without Keeogo™. Muscle activity, kinetics and postural control were analyzed during the sit-to-stand (sitTS), and compared to an age- and sex-matched healthy control. Results: Successful users of Keeogo™ have a moderate level of functionality (BBS: 46-51 s and/or TUG: 8-12 s). Wearing Keeogo™ improved performance on the 30CST, SCT and improved motor control, postural control and movement kinetics during the sitTS task in a chronic stroke survivor with significant hemiparesis. Conclusion: This is the first study providing data to help to identify which individuals with neurological impairment might benefit from using Keeogo™ dermoskeleton, together with new information quantifying its functional benefit to the user. Implications for Rehabilitation Keeogo™ is a user-initiated dermoskeleton that has been designed to assist individuals with mobility impairments to participate more effectively in activities of daily living (ADLs). Moderately impaired individuals have the greatest potential to benefit from using the device. Benefits of wearing the device include improvements in walking speed and endurance, performance on ADLs, motor control, kinetics, and postural control.

Correction: Evidence-based scientific exercise guidelines for adults with spinal cord injury: an update and a new guideline.

Authors Victoria L. Goosey-Tolfrey and Karen M. Smith were listed under the incorrect affiliations at the time of publication.

Feasibility, Safety, and Preliminary Effectiveness of a Home-Based Self-Managed High-Intensity Interval Training Program Offered to Long-Term Manual Wheelchair Users.

OBJECTIVES: To investigate and compare the feasibility, safety, and preliminary effectiveness of home-based self-managed manual wheelchair high-intensity interval training (HIIT) and moderate-intensity continuous training (MICT) programs. METHODS: Eleven manual wheelchair users were randomly assigned to the HIIT (n = 6) or the MICT group (n = 5). Both six-week programs consisted of three 40-minute propulsion training sessions per week. The HIIT group alternated between 30 s high-intensity intervals and 60 s low-intensity intervals, whereas the MICT group maintained a constant moderate intensity. Cardiorespiratory fitness, upper limb strength, and shoulder pain were measured before and after the programs. Participants completed a questionnaire on the programs that explored general areas of feasibility. RESULTS: The answers to the questionnaire demonstrated that both training programs were feasible in the community. No severe adverse events occurred, although some participants experienced increased shoulder pain during HIIT. Neither program yielded a significant change in cardiorespiratory fitness or upper limb strength. However, both groups reported moderate to significant subjective improvement. CONCLUSION: Home-based wheelchair HIIT appears feasible and safe although potential development of shoulder pain remains a concern and should be addressed with a future preventive shoulder exercise program. Some recommendations have been proposed for a larger study aiming to strengthen evidence regarding the feasibility, safety, and effectiveness of HIIT.

Assessing Ventilatory Threshold in Individuals With Motor-Complete Spinal Cord Injury.

OBJECTIVE: To assess the feasibility of measuring ventilatory threshold (VT) in higher-level motor-complete spinal cord injury (SCI) using 4 different analysis methods based on noninvasive gas exchange. DESIGN: Observational. SETTING: Laboratory testing. PARTICIPANTS: Individuals with C4-T6 motor-complete SCI (16 paraplegia, 22 tetraplegia; American Spinal Injury Association Impairment Scale A/B; 42±10 years old). INTERVENTIONS: Not applicable. MAIN OUTCOME: VT from a graded arm cycling test to volitional exhaustion using 4 methods: ventilatory equivalents, excess CO2, V-slope, and combined method. RESULTS: VT could be identified in all individuals with paraplegia, but in only 68% of individuals with tetraplegia. Individuals without observable VT completed the graded exercise test with lower ventilatory rate, peak power output, and peak oxygen consumption (Vo2peak) (all P<.05), compared to those with a detectable VT. Bland-Altman plots indicate minimal bias between methods (range: 0.01-0.03 L/min), with 95% limits of agreement of the difference within 0.25 L/min. Absolute V.o2 at VT with individual methods were all correlated to peak power output (r>0.74; P<.01) and Vo2peak (r>0.91; P<.01), with negligible differences between methods. CONCLUSIONS: The assessment of VT is a feasible alternative to peak exercise testing for aerobic fitness in individuals with higher-level, motor-complete SCI, although care should be taken when interpreting VT in individuals with tetraplegia who have lower cardiorespiratory fitness and lower peak power outputs.

Evidence-based scientific exercise guidelines for adults with spinal cord injury: an update and a new guideline.

OBJECTIVES: To describe the process and outcomes of using a new evidence base to develop scientific guidelines that specify the type and minimum dose of exercise necessary to improve fitness and cardiometabolic health in adults with spinal cord injury (SCI). SETTING: International. METHODS: Using Appraisal of Guidelines, Research and Evaluation (AGREE) II reporting criteria, steps included (a) determining the guidelines' scope; (b) conducting a systematic review of relevant literature; (c) holding three consensus panel meetings (European, Canadian and International) to formulate the guidelines; (d) obtaining stakeholder feedback; and (e) process evaluation by an AGREE II consultant. Stakeholders were actively involved in steps (c) and (d). RESULTS: For cardiorespiratory fitness and muscle strength benefits, adults with a SCI should engage in at least 20 min of moderate to vigorous intensity aerobic exercise 2 times per week AND 3 sets of strength exercises for each major functioning muscle group, at a moderate to vigorous intensity, 2 times per week (strong recommendation). For cardiometabolic health benefits, adults with a SCI are suggested to engage in at least 30 min of moderate to vigorous intensity aerobic exercise 3 times per week (conditional recommendation). CONCLUSIONS: Through a systematic, rigorous, and participatory process involving international scientists and stakeholders, a new exercise guideline was formulated for cardiometabolic health benefits. A previously published SCI guideline was endorsed for achieving fitness benefits. These guidelines represent an important step toward international harmonization of exercise guidelines for adults with SCI, and a foundation for developing exercise policies and programs for people with SCI around the world.

Reliability and minimal detectable change of a new treadmill-based progressive workload incremental test to measure cardiorespiratory fitness in manual wheelchair users.

BACKGROUND: Cardiorespiratory fitness training is commonly provided to manual wheelchair users (MWUs) in rehabilitation and physical activity programs, emphasizing the need for a reliable task-specific incremental wheelchair propulsion test. OBJECTIVE: Quantifying test-retest reliability and minimal detectable change (MDC) of key cardiorespiratory fitness measures following performance of a newly developed continuous treadmill-based wheelchair propulsion test (WPTTreadmill). METHODS: Twenty-five MWUs completed the WPTTreadmill on two separate occasions within one week. During these tests, participants continuously propelled their wheelchair on a motorized treadmill while the exercise intensity was gradually increased every minute until exhaustion by changing the slope and/or speed according to a standardized protocol. Peak oxygen consumption (VO2peak), carbon dioxide production (VCO2peak), respiratory exchange ratio (RERpeak), minute ventilation (VEpeak) and heart rate (HRpeak) were computed. Time to exhaustion (TTE) and number of increments completed were also measured. Intra-class correlation coefficients (ICC) were calculated to determine test-retest reliability. Standard error of measurement (SEM) and MDC90% values were calculated. RESULTS: Excellent test-retest reliability was reached for almost all outcome measures (ICC=0.91-0.76), except for RERpeak (ICC=0.58), which reached good reliability. TTE (ICC=0.89) and number of increments (ICC=0.91) also reached excellent test-retest reliability. For the main outcome measures (VO2peak and TTE), absolute SEM was 2.27 mL/kg/min and 0.76 minutes, respectively and absolute MDC90% was 5.30 mL/kg/min and 1.77 minutes, respectively. CONCLUSION: The WPTTreadmill is a reliable test to assess cardiorespiratory fitness among MWUs. TTE and number of increments could be used as reliable outcome measures when VO2 measurement is not possible.

Effects of exercise on fitness and health of adults with spinal cord injury: A systematic review.

OBJECTIVE: To synthesize and appraise research testing the effects of exercise interventions on fitness, cardiometabolic health, and bone health among adults with spinal cord injury (SCI). METHODS: Electronic databases were searched (1980-2016). Included studies employed exercise interventions for a period ≥2 weeks, involved adults with acute or chronic SCI, and measured fitness (cardiorespiratory fitness, power output, or muscle strength), cardiometabolic health (body composition or cardiovascular risk factors), or bone health outcomes. Evidence was synthesized and appraised using Grading of Recommendations Assessment, Development, and Evaluation (GRADE). RESULTS: A total of 211 studies met the inclusion criteria (22 acute, 189 chronic). For chronic SCI, GRADE confidence ratings were moderate to high for evidence showing exercise can improve all of the reviewed outcomes except bone health. For acute SCI, GRADE ratings were very low for all outcomes. For chronic SCI, there was low to moderate confidence in the evidence showing that 2-3 sessions/week of upper body aerobic exercise at a moderate to vigorous intensity for 20-40 minutes, plus upper body strength exercise (3 sets of 10 repetitions at 50%-80% 1-repetition maximum for all large muscle groups), can improve cardiorespiratory fitness, power output, and muscle strength. For chronic SCI, there was low to moderate confidence in the evidence showing that 3-5 sessions per week of upper body aerobic exercise at a moderate to vigorous intensity for 20-44 minutes can improve cardiorespiratory fitness, muscle strength, body composition, and cardiovascular risk. CONCLUSIONS: Exercise improves fitness and cardiometabolic health of adults with chronic SCI. The evidence on effective exercise types, frequencies, intensities, and durations should be used to formulate exercise guidelines for adults with SCI.

Formulation of evidence-based messages to promote the use of physical activity to prevent and manage Alzheimer's disease.

BACKGROUND: The impending public health impact of Alzheimer's disease is tremendous. Physical activity is a promising intervention for preventing and managing Alzheimer's disease. However, there is a lack of evidence-based public health messaging to support this position. This paper describes the application of the Appraisal of Guidelines Research and Evaluation II (AGREE-II) principles to formulate an evidence-based message to promote physical activity for the purposes of preventing and managing Alzheimer's disease. METHODS: A messaging statement was developed using the AGREE-II instrument as guidance. Methods included (a) conducting a systematic review of reviews summarizing research on physical activity to prevent and manage Alzheimer's disease, and (b) engaging stakeholders to deliberate the evidence and formulate the messaging statement. RESULTS: The evidence base consisted of seven systematic reviews focused on Alzheimer's disease prevention and 20 reviews focused on symptom management. Virtually all of the reviews of symptom management conflated patients with Alzheimer's disease and patients with other dementias, and this limitation was reflected in the second part of the messaging statement. After deliberating the evidence base, an expert panel achieved consensus on the following statement: "Regular participation in physical activity is associated with a reduced risk of developing Alzheimer's disease. Among older adults with Alzheimer's disease and other dementias, regular physical activity can improve performance of activities of daily living and mobility, and may improve general cognition and balance." The statement was rated favourably by a sample of older adults and physicians who treat Alzheimer's disease patients in terms of its appropriateness, utility, and clarity. CONCLUSION: Public health and other organizations that promote physical activity, health and well-being to older adults are encouraged to use the evidence-based statement in their programs and resources. Researchers, clinicians, people with Alzheimer's disease and caregivers are encouraged to adopt the messaging statement and the recommendations in the companion informational resource.

Exercise Training in Progressive Multiple Sclerosis: A Comparison of Recumbent Stepping and Body Weight-Supported Treadmill Training.

Background: There is evidence of the benefits of exercise training in multiple sclerosis (MS); however, few studies have been conducted in individuals with progressive MS and severe mobility impairment. A potential exercise rehabilitation approach is total-body recumbent stepper training (TBRST). We evaluated the safety and participant-reported experience of TBRST in people with progressive MS and compared the efficacy of TBRST with that of body weight-supported treadmill training (BWSTT) on outcomes of function, fatigue, and health-related quality of life (HRQOL). Methods: Twelve participants with progressive MS (Expanded Disability Status Scale scores, 6.0-8.0) were randomized to receive TBRST or BWSTT. Participants completed three weekly sessions (30 minutes) of exercise training for 12 weeks. Primary outcomes included safety assessed as adverse events and patient-reported exercise experience assessed as postexercise response and evaluation of exercise equipment. Secondary outcomes included the Multiple Sclerosis Functional Composite, the Modified Fatigue Impact Scale, and the Multiple Sclerosis Quality of Life-54 questionnaire scores. Assessments were conducted at baseline and after 12 weeks. Results: Safety was confirmed in both exercise groups. Participants reported enjoying both exercise modalities; however, TBRST was reviewed more favorably. Both interventions reduced fatigue and improved HRQOL (P ≤ .05); there were no changes in function. Conclusions: Both TBRST and BWSTT seem to be safe, well tolerated, and enjoyable for participants with progressive MS with severe disability. Both interventions may also be efficacious for reducing fatigue and improving HRQOL. TBRST should be further explored as an exercise rehabilitation tool for patients with progressive MS.

Following the Physical Activity Guidelines for Adults With Spinal Cord Injury for 16 Weeks Does Not Improve Vascular Health: A Randomized Controlled Trial.

OBJECTIVE: To evaluate the effects of following the physical activity guidelines (PAG) for adults with spinal cord injury (SCI) for 16 weeks. DESIGN: Randomized controlled trial. SETTING: Community exercise program. PARTICIPANTS: Individuals with SCI (N=23; neurological level of injury, C3-T11; American Spinal Injury Association Impairment Scale A-C; time postinjury, 12.0±9.9 y; age, 41.4±11.6 y). INTERVENTIONS: Participants were randomly assigned to PAG training (n=12) or active control (n=11) groups. PAG training involved ≥20 minutes of moderate-vigorous aerobic exercise (rating of perceived exertion 3-6 on 10-point scale) and 3×10 repetitions of upper-body strengthening exercises (50%-70% 1 repetition maximum) 2 times per week. The control group maintained existing physical activity levels with no guidance on training intensity. MAIN OUTCOME MEASURES: Outcome measures were obtained pre- and postintervention. Vascular health indicators included arterial stiffness via carotid distensibility and pulse wave velocity, and endothelial function via flow-mediated-dilation. Fasted blood samples were analyzed for markers of cardiovascular disease (CVD) risk. Body composition was assessed via anthropometrics and with dual-energy x-ray absorptiometry. RESULTS: Twenty-one individuals completed the intervention (PAG=12, control=9). Group-by-time interactions were observed for whole-body mass (P=.03), whole-body fat (P=.04), visceral adipose tissue (P=.04), and carotid artery distensibility (P=.05), suggesting maintained body composition and carotid stiffness in the PAG group concurrent with declines in the control group. No changes were found in any other outcome measure. CONCLUSIONS: While 16 weeks of adherence to the PAG in adults with SCI is insufficient to improve many markers of CVD risk, it may prevent declines in others. The PAG should continue to be promoted as a means to increase physical fitness and maintain body composition in individuals with SCI, but changes may be needed to achieve other health outcomes.

Metabolic demand and muscle activation during different forms of bodyweight supported locomotion in men with incomplete SCI.

Body weight supported locomotor training uses neuroplasticity principles to improve recovery following a spinal cord injury (SCI). Steady state locomotion using the same body weight support (BWS) percent was compared in 7 males (42.6 ± 4.29 years) with incomplete SCI and matched (gender, age) noninjured controls (42.7 ± 5.4 years) using the Lokomat, Manual Treadmill, and ZeroG. The VO2000, Polar Heart Rate (HR) Monitor, and lower limb electromyography (EMG) electrodes were worn during the 2-minute sessions. Oxygen uptake (VO2) and HR were expressed as percentage of peak values obtained using progressive arm ergometry; VO2 was also expressed relative to resting metabolic equivalents (METS). Filtered EMG signals from tibialis anterior (TA), rectus femoris (RF), biceps femoris (BF), and medial gastrocnemius (MG) were normalized to ZeroG stepping. The Lokomat required 30% of VO2 peak (2METS) compared to ~54% (3METS) for Manual Treadmill and ZeroG sessions. HR was 67% of peak during Lokomat sessions compared to ~83% for Manual Treadmill and ZeroG. Muscle activation was higher in treadmill conditions compared to the ZeroG primarily due to increased BF activity. At the same level of BWS, locomotion using the Manual Treadmill or the ZeroG is more aerobically demanding than the Lokomat. Treadmill modalities encourage greater hip extensor activation compared to overground locomotion.

Muscle activation during body weight-supported locomotion while using the ZeroG.

The ZeroG provides dynamic body weight support (BWS) using a harness while individuals with mobility impairments (e.g., spinal cord injury) ambulate overground. Muscle activity during locomotion using this device was studied in 13 nondisabled adults (age 23.8 +/- 2.7 yr). Electromyography (EMG) recordings were collected from tibialis anterior (TA), medial gastrocnemius (MG), rectus femoris (RF), and biceps femoris muscles during randomized walking trials at preferred speeds under five levels of BWS (0%, 20%, 40%, 60%, 80%). Filtered EMG signals from each trial were normalized to 0% BWS and correlated with gait phases. Muscle activity, averaged across muscles, decreased significantly at heel strike by 33.4% with increasing BWS. Offloading significantly decreased heel strike activity of RF (62.8%), MG (35.5%), and TA (25.9%). Gait cycle completion time increased with BWS primarily because of increased swing phase time. These results summarizing the effect of BWS on muscle activation during ambulation can now be compared with clinical populations using the ZeroG.