Walking net V ˙ O2 rises with advancing age in older women: where to go from here?

PURPOSE: Walking net V ˙ O2 tends to increase with advancing age; however, factors contributing to this relationship have not been widely described. The implications of such findings could inform targeted strategies to promote independent mobility in older adults. Herein, we evaluated the relationship between net V ˙ O2 and age at two submaximal workloads while exploring potential moderators of this relationship. METHODS: Secondary analyses were performed on 35 older (65 ± 3 years) women who completed a battery of physical assessments including fixed-speed, non-graded and graded (+ 2.5%) treadmill walking with indirect calorimetry to determine net V ˙ O2. Maximal oxygen uptake ( V ˙ O2max), knee extensor maximal isometric voluntary contraction (MVC), peak rate of torque development (RTD), and plantar flexor range-of-motion (PFROM) were also measured. RESULTS: Bivariate correlations showed non-graded (r = 0.403, p = 0.017) and graded (r = 0.413, p = 0.014) net V ˙ O2 were positively related to age. Notably, these relationships strengthened after adjusting for V ˙ O2max. Regression modeling showed age, RTD:MVC ratio (composite of muscle performance), and PFROM together explained 49% and 34% of the variance in non-graded and graded net V ˙ O2, respectively. Further analyses suggested knee extensor MVC moderates the relationship between non-graded net V ˙ O2 and age, accounting for 9% of the variance [ΔR2 = 0.090, F (1,31) = 4.13, p = 0.05]. CONCLUSION: These data support the premise that, in older women, walking net V ˙ O2 rises with advancing age, and additionally, the RTD:MVC ratio and PFROM are independent correlates of non-graded net V ˙ O2. Exercise interventions with a high degree of training specificity including explosive, velocity-based elements may promote independent mobility in older women.

Quantification and characterization of grouped type I myofibers in human aging.

INTRODUCTION: Myofiber type grouping is a histological hallmark of age-related motor unit remodeling. Despite the accepted concept that denervation-reinnervation events lead to myofiber type grouping, the completeness of those conversions remains unknown. METHODS: Type I myofiber grouping was assessed in vastus lateralis biopsies from Young (26 ± 4 years; n = 27) and Older (66 ± 4 years; n = 91) adults. Grouped and ungrouped type I myofibers were evaluated for phenotypic differences. RESULTS: Higher type I grouping in Older versus Young was driven by more myofibers per group (i.e., larger group size) (P < 0.05). In Older only, grouped type I myofibers displayed larger cross-sectional area, more myonuclei, lower capillary supply, and more sarco(endo)plasmic reticulum calcium ATPase I (SERCA I) expression (P < 0.05) than ungrouped type I myofibers. DISCUSSION: Grouped type I myofibers retain type II characteristics suggesting that conversion during denervation-reinnervation events is either progressive or incomplete. Muscle Nerve 57: E52-E59, 2018.

Racial Differences in Weight Gain: A 5-Year Longitudinal Study of Persons With Spinal Cord Injury.

OBJECTIVE: To assess racial differences in body mass index (BMI) change over 5 years among people with spinal cord injury (SCI). DESIGN: Multicenter longitudinal study. SETTING: Spinal Cord Injury Model Systems centers. PARTICIPANTS: Individuals (N=437; 313 non-Hispanic white, 81 non-Hispanic black, and 43 Hispanic; 335 men; mean age, 41.3±13.5y) who incurred an SCI from 1974 to 2010 and completed 2 follow-up assessments within 5 years between October 1, 2006 and September 18, 2015 (mean duration of injury, 9.1±9.6y at the start of the 5-year follow-up). INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURES: BMI (in kilograms per meters squared). RESULTS: The mean BMI of 437 participants increased from 26.4±6.3 to 27.0±6.4kg/m2 over 5 years (P=.002). The greatest increase was noted for Hispanics (2.0±5.7kg/m2; P=.02), followed by non-Hispanic whites (0.6±3.9kg/m2; P=.01) and non-Hispanic blacks (0.01±3.7kg/m2; P>.99). The differences in BMI increase across racial groups were significant (P=.03) in those with paraplegia (American Spinal Injury Association Impairment Scale A, B or C), those who were underweight or of normal weight at baseline, and those within 10 years of their injury. Such racial differences remained significant after taking into account demographic and injury characteristics. CONCLUSIONS: Our study findings provide a foundation for future research to explore risk and protective factors that contribute to racial differences in weight gain after SCI, which help alert health care professionals to a high-risk group for obesity prevention and management.

Characteristics of Adults With Neurologic Disability Recruited for Exercise Trials: A Secondary Analysis.

This review examined demographic and clinical characteristics of participants from exercise trials in 3 neurologic disability conditions (multiple sclerosis, spinal cord injury, and traumatic brain injury) and compared these data with population-based statistics. The authors included 75 published studies from 2006 to 2016: 53 studies for multiple sclerosis (n = 2,034), 14 for spinal cord injury (n = 302), and 8 for traumatic brain injury (n = 272). Pooled data resembled some heterogeneous aspects of population data sets. However, many characteristics were not reported; samples were small and predominantly White, and 48.1% of the people screened were excluded. Thus, findings from these studies may not be translatable across the range of people with these three conditions, which warrant efforts to target the inclusion of underrepresented subgroups in future exercise trials.

High-Intensity Exercise Acutely Increases Substantia Nigra and Prefrontal Brain Activity in Parkinson's Disease.

BACKGROUND Pathologic alterations in resting-state brain activity patterns exist among individuals with Parkinson's disease (PD). Since physical exercise alters resting-state brain activity in non-PD populations and improves PD symptoms, we assessed the acute effect of exercise on resting-state brain activity in exercise-trained individuals with PD. MATERIAL AND METHODS Resting-state functional magnetic resonance imaging (fMRI) was collected twice for 17 PD participants at the conclusion of an exercise intervention. The acute effect of exercise was examined for PD participants using the amplitude of low frequency fluctuation (ALFF) before and after a single bout of exercise. Correlations of clinical variables (i.e., PDQ-39 quality of life and MDS-UPDRS) with ALFF values were examined for the exercise-trained PD participants. RESULTS An effect of acute exercise was observed as an increased ALFF signal within the right ventromedial prefrontal cortex (PFC), left ventrolateral PFC, and bilaterally within the substantia nigra (SN). Quality of life was positively correlated with ALFF values within the vmPFC and vlPFC. CONCLUSIONS Given the role of the SN and PFC in motor and non-motor symptoms in PD, the acute increases in brain activity within these regions, if repeated frequently over time (i.e., exercise training), may serve as a potential mechanism underlying exercise-induced PD-specific clinical benefits.

Heightened TWEAK-NF-κB signaling and inflammation-associated fibrosis in paralyzed muscles of men with chronic spinal cord injury.

Individuals with long-standing spinal cord injury (SCI) often present with extreme muscle atrophy and impaired glucose metabolism at both the skeletal muscle and whole body level. Persistent inflammation and increased levels of proinflammatory cytokines in the skeletal muscle are potential contributors to dysregulation of glucose metabolism and atrophy; however, to date no study has assessed the effects of long-standing SCI on their expression or intracellular signaling in the paralyzed muscle. In the present study, we assessed the expression of genes (TNFαR, TNFα, IL-6R, IL-6, TWEAK, TWEAK R, atrogin-1, and MuRF1) and abundance of intracellular signaling proteins (TWEAK, TWEAK R, NF-κB, and p-p65/p-50/105) that are known to mediate inflammation and atrophy in skeletal muscle. In addition, based on the effects of muscle inflammation on promotion of skeletal muscle fibrosis, we assessed the degree of fibrosis between myofibers and fascicles in both groups. For further insight into the distribution and variability of muscle fiber size, we also analyzed the frequency distribution of SCI fiber size. Resting vastus lateralis (VL) muscle biopsy samples were taken from 11 men with long-standing SCI (≈22 yr) and compared with VL samples from 11 able-bodied men of similar age. Our results demonstrated that chronic SCI muscle has heightened TNFαR and TWEAK R gene expression and NF-κB signaling (higher TWEAK R and phospho-NF-κB p65) and fibrosis, along with substantial myofiber size heterogeneity, compared with able-bodied individuals. Our data suggest that the TWEAK/TWEAK R/NF-κB signaling pathway may be an important mediator of chronic inflammation and fibrotic adaptation in SCI muscle.

Mechanosensitivity may be enhanced in skeletal muscles of spinal cord-injured versus able-bodied men.

We investigated the effects of an acute bout of neuromuscular electrical stimulation-induced resistance exercise (NMES-RE) on intracellular signaling pathways involved in translation initiation and mechanical loading-induced muscle hypertrophy in spinal cord-injured (SCI) versus able-bodied (AB) individuals. AB and SCI individuals completed 90 isometric knee extension contractions at 30% of maximum voluntary or evoked contraction, respectively. Muscle biopsies were collected before, and 10 and 60 min after NMES-RE. Protein levels of α7- and ß1-integrin, phosphorylated and total GSK-3α/ß, S6K1, RPS6, 4EBP1, and FAK were assessed by immunoblotting. SCI muscle appears to be highly sensitive to muscle contraction even several years after the injury, and in fact it may be more sensitive to mechanical stress than AB muscle. Heightened signaling associated with muscle mechanosensitivity and translation initiation in SCI muscle may be an attempted compensatory response to offset elevated protein degradation in atrophied SCI muscle. .

Frequency of combined resistance and aerobic training in older women.

The aim of this study was to determine the optimal frequency of combined aerobic and resistance training for improving muscular strength (MS), cardiovascular fitness (CF), and functional tasks (FTs) in women older than 60 years. Sixty-three women were randomly assigned to 1 of 3 exercise training groups. Group 1 performed 1 resistance exercise training (RET) and 1 aerobic exercise training (AET) session per week (AET/RET 1 × wk); group 2 performed 2 RET and 2 AET sessions per week (AET/RET 2 × wk); and group 3 performed 3 RET and 3 AET sessions per week (AET/RET 3 × wk). MS, CF, and FT measurements were made pretraining and 16 weeks posttraining. Repeated-measures analysis of variance indicated a significant time effect for changes in MS, CF, and FT, such that all improved after training. However, there were no significant training group or training group × time interactions. Sixteen weeks of combined AET/RET (1 × wk, 2 × wk, or 3 × wk) lead to significant improvements in MS, CF, exercise economy, and FT. However, there were no significant differences for MS, CF, or FT outcomes between groups.

Optimal neuromuscular electrical stimulation parameters after spinal cord injury.

PURPOSE: To examine the interrelationship of pulse duration and pulse frequency on torque production and muscle fatigue in both impaired and non-impaired skeletal muscle of men and women. METHODS: Individuals with [n = 14 (6 females), 38 ± 13 yr; 175 ± 11 cm; 76 ± 20 kg] and without [n = 14 (6 females), 29 ± 8 yr; 175 ± 9 cm; 74 ± 14 kg] spinal cord injury (SCI) participated. Muscle torque was recorded during a series of NMES-induced isometric muscle contractions using different combinations of pulse durations and frequencies. Additionally, two different muscle fatigue protocols (20 and 50 Hz/200µs) were utilized to elicit repeat isometric muscle contractions (1s on and 1s off × 3 min). RESULTS: There was a statistically significant linear trend for pulse charge (the product of pulse frequency and pulse duration) on isometric torque production in participants without (p < 0.001, η2 = 0.79), and in participants with SCI (p < 0.001, η2 = 0.66), with higher total pulse charge generating higher torque values. Participants with SCI had significantly greater muscle fatigue for both muscle fatigue protocols (p < 0.05). CONCLUSIONS: NMES protocols should consider using longer pulse durations with lower frequencies to maximize force production for individuals with SCI. However, because mechanisms of muscle fatigue may be different for impaired muscle when compared to non-impaired muscle, further studies on protocols to offset fatigue are warranted.

Lifting Techniques: Why Are We Not Using Evidence To Optimize Movement?

Lifting something off the ground is an essential task and lifting is a documented risk factor for low back pain (LBP). The standard lifting techniques are stoop (lifting with your back), squat (lifting with your legs), and semi-squat (midway between stoop and squat). Most clinicians believe the squat technique is optimal; however, training on squat lifting does not prevent LBP and utilizing greater lumbar flexion (i.e. stoop) when lifting is not a risk factor for LBP. The disconnect between what occurs in clinical practice and what the evidence suggests has resulted in ongoing debate. Clinicians must ask the right questions in order to apply the evidence appropriately. A proposed clinical framework of calm tissue down, build tissue up, improve work capacity can be used to determine which lifting technique is optimal for a patient at any given time. When applying this clinical framework, clinicians should consider metabolic, biomechanical, physical stress tolerance, and pain factors in order to address the movement system. For example, stoop lifting is more metabolically efficient and less challenging to the cardiopulmonary system. There may be few biomechanical differences in spinal postures and gross loads on the lumbar spine between stoop, squat, and semi-squat lifting; however, each lift has distinct kinematic patterns that affects muscle activation patterns, and ultimately the movement system. Clinicians must find the optimal dosage of physical stress to address all aspects of the movement system to minimize the risk of injury. There is no universal consensus on the optimal lifting technique which will satisfy every situation; however, there may be a lifting technique that optimizes movement to achieve a specific outcome. The calm tissue down, build tissue up, improve work capacity framework offers an approach to determine the best lifting technique for an individual patient at any give time. LEVEL OF EVIDENCE: 5.

Motor unit recruitment during neuromuscular electrical stimulation: a critical appraisal.

Neuromuscular electrical stimulation (NMES) is commonly used in clinical settings to activate skeletal muscle in an effort to mimic voluntary contractions and enhance the rehabilitation of human skeletal muscles. It is also used as a tool in research to assess muscle performance and/or neuromuscular activation levels. However, there are fundamental differences between voluntary- and artificial-activation of motor units that need to be appreciated before NMES protocol design can be most effective. The unique effects of NMES have been attributed to several mechanisms, most notably, a reversal of the voluntary recruitment pattern that is known to occur during voluntary muscle contractions. This review outlines the assertion that electrical stimulation recruits motor units in a nonselective, spatially fixed, and temporally synchronous pattern. Additionally, it synthesizes the evidence that supports the contention that this recruitment pattern contributes to increased muscle fatigue when compared with voluntary actions and provides some commentary on the parameters of electrical stimulation as well as emerging technologies being developed to facilitate NMES implementation. A greater understanding of how electrical stimulation recruits motor units, as well as the benefits and limitations of its use, is highly relevant when using this tool for testing and training in rehabilitation, exercise, and/or research.

Age, muscle fatigue, and walking endurance in pre-menopausal women.

Aging is associated with loss of endurance; however, aging is also associated with decreased fatigue during maximal isometric contractions. The aims of this study were to examine the relationship between age and walking endurance (WE) and maximal isometric fatigue (MIF) and to determine which metabolic/fitness components explain the expected age effects on WE and MIF. Subjects were 96 pre-menopausal women. Oxygen uptake (walking economy) was assessed during a 3-mph walk; aerobic capacity and WE by progressive treadmill test; knee extension strength by isometric contractions, MIF during a 90-s isometric plantar flexion (muscle metabolism measured by (31)P MRS). Age was related to increased walking economy (low VO(2), r = -0.19, P < 0.03) and muscle metabolic economy (force/ATP, 0.34, P = 0.01), and reduced MIF (-0.26, P < 0.03). However, age was associated with reduced WE (-0.28, P < 0.01). Multiple regression showed that muscle metabolic economy explained the age-related decrease in MIF (partial r for MIF and age -0.13, P = 0.35) whereas walking economy did not explain the age-related decrease in WE (partial r for WE and age -0.25, P < 0.02). Inclusion of VO(2max) and knee endurance strength accounted for the age-related decreased WE (partial r for WE and age = 0.03, P > 0.80). In premenopausal women, age is related to WE and MIF. In addition, these results support the hypothesis that age-related increases in metabolic economy may decrease MIF. However, decreased muscle strength and oxidative capacity are related to WE.

Effects of functional electrical stimulation on muscle health after spinal cord injury.

Spinal cord injury is a devastating condition interrupting voluntary movement and motor control. In response to unloading, skeletal muscle undergoes numerous adaptations, including rapid and profound atrophy, intramuscular fat accumulation, impaired muscular glucose metabolism and decreased force generation and muscle performance. Functional electrical stimulation (FES) involves electrically stimulating affected muscles to contract in a coordinated manner to create a functional movement or task. Effects of FES-cycling, rowing and resistance training on muscle health are described here. Briefly, FES-cycling and resistance training may slow muscle atrophy or facilitate muscle hypertrophy, and all modalities benefit muscle composition and performance to some extent. These interventions show promise as future rehabilitative tools after spinal cord injury.

Influence of muscle fatigue on contractile twitch characteristics in persons with parkinson's disease and older adults: A pilot study.

INTRODUCTION: It is widely accepted that pathophysiological changes to the central nervous system of persons with Parkinson's disease (PD) result in negative effects on motor function. However, less information is known regarding the pathology of PD on skeletal muscle. The purpose of this study was to determine the effect of a fatiguing isometric knee extension protocol on muscle mechanics using evoked twitch contractions in persons with PD and in non-impaired older adults (OLD). METHODS: Evoked twitch contractions were examined during a fatiguing protocol in PD (66 ± 9 yr, n = 8) and OLD (65 ± 10 yr, n = 5). Participants performed 5-sec maximal isometric voluntary contractions of the quadriceps femoris with 5-sec rest for 3-min. Every 30-sec during rest intervals, a maximal transcutaneous electrical stimulus was administered to the quadriceps femoris to quantify evoked peak twitch torque (pTT), peak relaxation rate (pRR), and peak rate of torque development (pRTD). RESULTS: A large effect of voluntary fatigue (%decline) was observed (g = 1.58). There were no significant differences in pTT (p = 0.09; 95% CI:-3.6, 0.28) or pRR (p = 0.11; 95% CI:-31, 3.6). However, the slope decline of pRTD in OLD (-35.4 ± 24.7) was greater than PD (-11.5 ± 11.4; p = 0.03), indicating that skeletal muscle in persons with PD is less fatigable compared to non-impaired older adults. CONCLUSION: The rate, not the maximum capacity, of torque generation of the muscle during a fatiguing knee extension protocol was affected by PD. Future studies are warranted to identify the mechanism(s) responsible for the observed differences in skeletal muscle contractile characteristics and potential myofiber distribution variation in PD.

The impact of varying interphase interval on neuromuscular electrical stimulation-induced quadriceps femoris muscle performance and perceived discomfort.

Objectives: Determine the effects of varying frequency, phase duration, and interphase interval (IPI) of symmetrical, biphasic pulsed current (SBPC) on quadriceps femoris muscle torque production, perceived discomfort, and muscle fatigue when using neuromuscular electrical stimulation (NMES).Methods: Ten recreationally active able-bodied participants completed this study. Muscle torque was measured during a series of laboratory based, NMES-induced muscle contractions with varying combinations of phase durations (50, 100, 150, or 200 µs) and IPIs (50, 100, 150, or 200 µs) at 25 and 50 Hz. A three-factorial repeated measures experimental design was used. After each contraction, participants rated perceived discomfort on a 10-cm visual analog scale. Subsequently, fatigue tests were conducted using different frequency-IPI combinations.Results: Results of within-subjects ANOVAs revealed no interaction among the three factors: frequency, phase duration and IPI. Significant main effects of phase duration and IPI, but not frequency, on torque production and perceived discomfort were observed. Specifically, significant linear and quadratic trends were observed for the effect of phase duration and IPI on torque production, and the effect of IPI on discomfort, and only a significant linear trend for the effect of phase duration on discomfort. The shorter IPI combined with the longer phase duration produced greater torque with tolerable discomfort. There was no significant effect of IPI on muscle fatigue.Conclusions: Study findings indicated that when administering SBPC on the quadriceps femoris muscle, clinicians should select an IPI of 50 µs and a longer phase duration (e.g. 200 µs) to maximize torque without imposing intolerable discomfort.

Gait training with progressive external auditory cueing in persons with Parkinson's disease.

OBJECTIVE: To investigate the progressively increasing external auditory cues during mobility training with persons with Parkinson's disease (PD). DESIGN: Experimental. SETTING: General community. PARTICIPANTS: Convenience sample of persons with PD (N=12) who walked independently. INTERVENTIONS: Gait training to external auditory cues was based on a participant's comfortable walking pace. Training external auditory cues rates were increased if patients were able to maintain or increase stride length with increasing external auditory cues rate. Movement synchronization was not monitored during training. Participants trained for 30min/session, 3 sessions/wk, for 8 weeks. MAIN OUTCOME MEASURES: Walking velocity, stride length, and cadence. RESULTS: Participants trained at a mean maximal rate of 157bpm. They showed a significant (P<.01) increase in walking velocity, stride length, and cadence after 8 weeks of training. CONCLUSIONS: Walking velocity, stride length, and cadence can significantly improve when community-dwelling persons with PD participate in progressive mobility training.

Exploring the uptake and implementation of tele-monitored home-exercise programmes in adults with Parkinson's disease: A mixed-methods pilot study.

BACKGROUND: People with Parkinson's disease experience numerous barriers to exercise participation at fitness facilities. Advances in tele-monitoring technologies create alternative channels for managing and supervising exercise programmes in the home. However, the success of these programmes will depend on participants' perceptions of using the technology and their exercise adherence. Thus, this pilot explored the uptake and implementation of two common methods of Internet-exercise training in Parkinson's disease. METHODS: Twenty adults with Parkinson's disease were randomized into either: telecoach-assisted exercise (TAE) or self-regulated exercise (SRE) groups. Both groups received the same eight-week exercise prescription (combined strength and aerobic exercise) and telehealth system that streamed and recorded vital signs and exercise data. TAE participants exercised under a telecoach's supervision via videoconferencing. SRE participants independently managed their exercise training. Quantitative data were described and qualitative data underwent thematic analysis. RESULTS: Quantitative results demonstrated that TAE participants achieved strong attendance (99.2%), whereas SRE participants demonstrated 35.9% lower attendance, 48% less total time exercising, and 74.5% less time exercising at moderate intensity. Qualitatively, TAE participants reported overtly favourable programme experiences and that assistance from a telecoach enhanced their exercise motivation. SRE participants noted several challenges that impeded adherence. CONCLUSION: Findings demonstrate that adults with Parkinson's disease acknowledge benefits of exercising through a telehealth system and are open to utilizing this channel as a means of exercise. However, human-interactive support may be required to overcome unique impediments to participation. Study findings warrant validation in larger trials that can transfer the success of TAE towards more scalable methods of delivery.

Multi-Level Factors Associated with Social Participation among Stroke Survivors: China's Health and Retirement Longitudinal Study (2011-2015).

BACKGROUND: This study aims to examine the impact of individual-level and community-based factors on popular social participation activities of Chinese middle-aged and older adults post-stroke. METHODS: Sub-samples of survivors of stroke (2011: n = 413, 2013: n = 395, 2015: n = 441) recruited by the China Health and Retirement Longitudinal Study (CHARLS) were included in the analysis. Zero-inflated Poisson and multi-level logistic regression models were used to explore factors associated with social participation. RESULTS: More than half of individuals (55.0%) had no social participation and 23.4% participated in multiple social activities. The most popular social activities that individuals participated in were interacting with friends (32.6%) and going to a community club to play table games (22.7%). Multiple individual-level factors were negatively related to social participation (e.g., depressive symptoms and multiple measures of functional limitations) while the allocation of an outdoor exercise facility in the community/village was positively associated with the participation of going to a community club to play table games. CONCLUSION: Stroke survivors are at high risk of limited social participation. Policymakers and other key stakeholders should consider community design among other potential solutions when identifying ways to link at-risk stroke survivors to both opportunities for rehabilitation (e.g., physical function) and social participation.

Effects of High-Intensity Interval Training Versus Moderate-Intensity Training on Cardiometabolic Health Markers in Individuals With Spinal Cord Injury: A Pilot Study.

Background: Recent studies in nondisabled individuals have demonstrated that low-volume high-intensity interval training (HIIT) can improve cardiometabolic health similar to moderate-intensity training (MIT) despite requiring 20% of the overall time commitment. To date, there have been no studies assessing the effects of HIIT for improving cardiometabolic health in individuals with SCI. Objectives: The primary purpose of this pilot study was to compare the effects of 6 weeks of low-volume HIIT vs MIT using arm crank ergometer exercise to improve body composition, cardiovascular fitness, glucose tolerance, blood lipids, and blood pressure in a cohort of individuals with longstanding SCI. Methods: Participants were randomized to 6 weeks of HIIT or MIT arm crank exercise training. Aerobic capacity, muscular strength, blood lipids, glucose tolerance, blood pressure, and body composition were assessed at baseline and 6 weeks post training. Results: Seven individuals (6 male, 1 female; n = 3 in MIT and n = 4 in HIIT; mean age 51.3 ± 10.5 years) with longstanding SCI completed the study. The preliminary findings from this pilot study demonstrated that individuals with SCI randomized to either 6 weeks of HIIT or MIT displayed improvements in (a) insulin sensitivity, (b) cardiovascular fitness, and (c) muscular strength (p < .05). However, MIT led to greater improvements in arm fat percent and chest press strength compared to HIIT (p < .05). Conclusion: No differences between MIT and HIIT were observed. Both conditions led to improvements in insulin sensitivity, aerobic capacity, muscle strength, and blood lipids in individuals with SCI. Future larger cohort studies are needed to determine if the shorter amount of time required from HIIT is preferable to current MIT exercise recommendations.

Sustainability of exercise intervention outcomes among people with disabilities: a secondary review.

BACKGROUND: This review explored the sustainability of health and physical activity-based outcomes following exercise trials that were conducted for people with disabilities, and characterised the influence of technology and behaviour change strategies. METHODS: A total of 132 studies were screened from an existing database. RESULTS: Only 22 studies featured follow-up periods and met eligibility criteria. At follow-up, studies typically reported at least one significant health outcome that was maintained (n = 18/21; 86%). However, significant health outcomes accounted for only 32% of the total volume of outcomes that were measured at follow-up. For physical activity-based outcomes, six studies (n = 6/8; 75%) reported that intervention gains were maintained throughout follow-up. The incorporation of technology or behaviour change strategies appeared to be linked with sustainable intervention effects. CONCLUSIONS: Overall, some evidence demonstrated that post-intervention effects were sustainable. However, the strength of the evidence was weak and several existing gaps in knowledge were identified. Moreover, most studies did not focus on sustainability, but instead emphasised short-term effects of exercise participation on health and physical activity outcomes. Study findings call for greater research and programme efforts to maintain health, function, and physical activity behaviour after supports provided by research studies are removed. Implications for rehabilitation Short-term exercise programmes may require additional strategies designed specifically to enhance the sustainability of exercise outcomes and physical activity participation. Incorporating technology within exercise interventions may enhance the likelihood of sustaining health and function outcomes. Exercise programmes framed within behaviour change theory can equip individuals with the appropriate strategies necessary to maintain their physical activity participation.