Influence of upper-body continuous, resistance or high-intensity interval training (CRIT) on postprandial responses in persons with spinal cord injury: study protocol for a randomised controlled trial

Therapeutic Lifestyle Intervention Targeting Enhanced Cardiometabolic Health and Function for Persons with Chronic Spinal Cord Injury in Caregiver/Care-Receiver Co-Treatment: A Study Protocol of a Multisite Randomized Controlled Trial

BACKGROUND

Chronic spinal cord injury (SCI) significantly accelerates morbidity and mortality, partly due to the increased risk of cardiometabolic diseases (CMD), including neurogenic obesity, dyslipidemia, and impaired glucose metabolism. While exercise and dietary interventions have shown some transient benefits in reducing CMD risk, they often fail to improve clinically relevant disease markers and cardiovascular events. Moreover, SCI also places caregiving demands on their caregivers, who themselves experience health and functional decline. This underscores the need for more substantial interventions that incorporate appropriate physical activity, heart-healthy nutrition, and behavioral support tailored to the SCI population.

OBJECTIVES

This randomized clinical trial (RCT) protocol will (1) assess the health and functional effects, user acceptance, and satisfaction of a 6-month comprehensive therapeutic lifestyle intervention (TLI) adapted from the National Diabetes Prevention Program (DPP) for individuals with chronic SCI and (2) examine the impact of a complementary caregiver program on the health and function of SCI caregivers and evaluate user acceptance and satisfaction. Caregivers (linked with their partners) will be randomized to 'behavioral support' or 'control condition'.

METHODS

Dyadic couples comprise individuals with SCI (18-65 years, >1-year post-injury, ASIA Impairment Scale A-C, injury levels C5-L1) and non-disabled SCI caregivers (18-65 years). Both groups undergo lock-step circuit resistance training, a calorie-restricted Mediterranean-style diet, and 16 educational sessions focused on diet/exercise goals, self-monitoring, psychological and social challenges, cognitive behavioral therapy, and motivational interviewing. The outcome measures encompass the cardiometabolic risks, cardiorespiratory fitness, inflammatory stress, multidimensional function, pain, life quality, independence, self-efficacy, program acceptance, and life satisfaction for SCI participants. The caregiver outcomes include multidimensional function, pain, quality of life, independence, and perceived caregiver burden.

DISCUSSION/CONCLUSIONS

This study evaluates the effects and durability of a structured, multi-modal intervention on health and function. The results and intervention material will be disseminated to professionals and consumers for broader implementation.

TRIAL REGISTRATION

ClinicalTrials.gov, ID: NCT02853149 Registered 2 August 2016.

Exercise to mitigate cardiometabolic disorders after spinal cord injury

The cardiometabolic disorder (CMD) is a syndrome caused by coalescing of cardiovascular, endocrine, pro-thrombotic, and inflammatory health risks. Together, these risks confer a hazard as health-threatening as coronary artery disease or type2 diabetes, whether an individual has a diagnosis of coronary disease or diabetes, or not. CMD is most often defined by three or more of five clinically assessed risk components, notably obesity, insulin resistance, hypertension, hypertriglyceridemia, and depressed high-density lipoprotein cholesterol. Evidence currently suggests that worldwide CMD is expanding at a pandemic rate, and it is known that people living with spinal cord injuries (SCI) qualify for the diagnosis at more than 50% of the prevalence of a non-disabled cohort. A recent evidence-based guideline warned of the current state of CMD following SCI and recommended early lifestyle intervention incorporating exercise and prudent nutrition as a first-line disease countermeasure. This monograph will define the CMD following SCI, explore its underlying pathophysiology, and provide evidence that recommends exercise for CMD health hazards after SCI.

Effects of Exercise Mode on Postprandial Metabolism in Humans with Chronic Paraplegia

PURPOSE

The purpose of this study was to assess the acute effects of exercise mode and intensity on postprandial macronutrient metabolism.

METHODS

Ten healthy men age 39 ± 10 yr with chronic paraplegia (13.2 ± 8.8 yr, ASIA A-C) completed three isocaloric bouts of upper-body exercise and a resting control. After an overnight fast, participants completed circuit resistance exercise (CRE) first and the following conditions in a randomized order, separated by >48 h: i) control (CON), ~45-min seated rest; ii) moderate-intensity continuous exercise (MICE), ~40-min arm cranking at a resistance equivalent to ~30% peak power output (PPO); and iii) high-intensity interval exercise (HIIE), ~30 min arm cranking with resistance alternating every 2 min between 10% PPO and 70% PPO. After each condition, participants completed a mixed-meal tolerance test consisting of a 2510-kJ liquid meal (35% fat, 50% carbohydrate, 15% protein). Blood and expired gas samples were collected at baseline and regular intervals for 150 min after a meal.

RESULTS

An interaction (P < 0.001) was observed, with rates of lipid oxidation elevated above CON in HIIE until 60 min after a meal and in CRE at all postprandial time points up to 150 min after a meal. Postprandial blood glycerol was greater in MICE (P = 0.020) and CRE (P = 0.001) compared with CON. Furthermore, nonesterified fatty acid area under the curve had a moderate-to-strong effect in CRE versus MICE and HIIE (Cohen's d = -0.76 and -0.50, respectively).

CONCLUSIONS

In persons with paraplegia, high-intensity exercise increased postprandial energy expenditure independent of the energy cost of exercise. Furthermore, exercise combining resistance and endurance modes (CRE) showed the greater effect on postprandial lipid oxidation.

Neither Postabsorptive Resting Nor Postprandial Fat Oxidation Are Related to Peak Fat Oxidation in Men With Chronic Paraplegia

The peak rate of fat oxidation (PFO) achieved during a graded exercise test is an important indicator of metabolic health. In healthy individuals, there is a significant positive association between PFO and total daily fat oxidation (FO). However, conditions resulting in metabolic dysfunction may cause a disconnect between PFO and non-exercise FO. Ten adult men with chronic thoracic spinal cord injury (SCI) completed a graded arm exercise test. On a separate day following an overnight fast (≥ 10 h), they rested for 60 min before ingesting a liquid mixed meal (600 kcal; 35% fat, 50% carbohydrate, 15% protein). Expired gases were collected and indirect calorimetry data used to determine FO at rest, before and after feeding, and during the graded exercise test. Participants had “good” cardiorespiratory fitness (VO_2peak: 19.2 ± 5.2 ml/kg/min) based on normative reference values for SCI. There was a strong positive correlation between PFO (0.30 ± 0.08 g/min) and VO_2peak (r = 0.86, p = 0.002). Additionally, postabsorptive FO at rest was significantly and positively correlated with postprandial peak FO (r = 0.77, p = 0.01). However, PFO was not significantly associated with postabsorptive FO at rest (0.08 ± 0.02 g/min; p = 0.97), postprandial peak FO (0.10 ± 0.03 g/min; p = 0.43), or incremental area under the curve postprandial FO (p = 0.22). It may be advantageous to assess both postabsorptive FO at rest and PFO in those with SCI to gain a more complete picture of their metabolic flexibility and long-term metabolic health.

Effect of Paraplegia on the Time Course of Exogenous Fatty Acid Incorporation Into the Plasma Triacylglycerol Pool in the Postprandial State

Spinal cord injury (SCI) results in disordered fat metabolism. Autonomic decentralization might contribute to dyslipidemia in SCI, in part by influencing the uptake of dietary fats through the gut-lymph complex. However, the neurogenic contributions to dietary fat metabolism are unknown in this population. We present a subset of results from an ongoing registered clinical trial (NCT03691532) related to dietary fat absorption. We fed a standardized (20 kcal⋅kgFFM^–1) liquid meal tolerance test (50% carb, 35% fat, and 15% protein) that contained stable isotope lipid tracer (5 mg⋅kgFFM^–1 [U-¹³C]palmitate) to persons with and without motor complete thoracic SCI. Blood samples were collected at six postprandial time points over 400 min. Changes in dietary fatty acid incorporated into the triacylglycerol (TAG) pool (“exogenous TAG”) were used as a marker of dietary fat absorption. This biomarker showed that those with paraplegia had a lower amplitude than non-injured participants at Post₂₄₀ (52.4 ± 11.0 vs. 77.5 ± 16.0 μM), although this failed to reach statistical significance (p = 0.328). However, group differences in the time course of absorption were notable. The injury level was also strongly correlated with time-to-peak exogenous TAG concentration (r = −0.806, p = 0.012), with higher injuries resulting in a slower rise in exogenous TAG. This time course documenting exogenous TAG change is the first to show a potential neurogenic alteration in SCI dietary fat absorption.

Exercise Interventions Targeting Obesity in Persons With Spinal Cord Injury

Spinal cord injury (SCI) results in an array of cardiometabolic complications, with obesity being the most common component risk of cardiometabolic disease (CMD) in this population. Recent Consortium for Spinal Cord Medicine Clinical Practice Guidelines for CMD in SCI recommend physical exercise as a primary treatment strategy for the management of CMD in SCI. However, the high prevalence of obesity in SCI and the pleiotropic nature of this body habitus warrant strategies for tailoring exercise to specifically target obesity. In general, exercise for obesity management should aim primarily to induce a negative energy balance and secondarily to increase the use of fat as a fuel source. In persons with SCI, reductions in the muscle mass that can be recruited during activity limit the capacity for exercise to induce a calorie deficit. Furthermore, the available musculature exhibits a decreased oxidative capacity, limiting the utilization of fat during exercise. These constraints must be considered when designing exercise interventions for obesity management in SCI. Certain forms of exercise have a greater therapeutic potential in this population partly due to impacts on metabolism during recovery from exercise and at rest. In this article, we propose that exercise for obesity in SCI should target large muscle groups and aim to induce hypertrophy to increase total energy expenditure response to training. Furthermore, although carbohydrate reliance will be high during activity, certain forms of exercise might induce meaningful postexercise shifts in the use of fat as a fuel. General activity in this population is important for many components of health, but low energy cost of daily activities and limitations in upper body volitional exercise mean that exercise interventions targeting utilization and hypertrophy of large muscle groups will likely be required for obesity management.

Physiological responses to moderate intensity continuous and high-intensity interval exercise in persons with paraplegia

STUDY DESIGN

Randomized crossover.

OBJECTIVES

To test differences in the duration and magnitude of physiological response to isocaloric moderate intensity continuous (MICE) and high-intensity interval exercise (HIIE) sessions in persons with spinal cord injury (SCI).

SETTING

Academic medical center in Miami, FL, USA.

METHODS

Ten adult men (mean ± s.d.; 39 ± 10 year old) with chronic (13.2 ± 8.8 year) paraplegia (T2-T10) completed a graded exercise test. Then, in a randomized order, participants completed MICE and HIIE for a cost of 120 kcal. MICE was performed at 24.6% PO_peak. During HIIE, exercise was completed in 2 min work and recovery phases at 70%:10% PO_peak.

RESULTS

MICE and HIIE were isocaloric (115.9 ± 21.8 and 116.6 ± 35.0 kcal, respectively; p = 0.903), but differed in duration (39.8 ± 4.6 vs 32.2 ± 6.2 min; p < 0.001) and average respiratory exchange ratio (RER; 0.90 ± 0.08 vs 1.01 ± 0.07; p = 0.002). During MICE, a workrate of 24.6 ± 6.7% PO_peak elicited a V̇O₂ of 53.1 ± 6.5% V̇O_2peak (10.1 ± 2.2 ml kg^-1 min^-1). During HIIE, a workrate at 70% PO_peak elicited 88.3 ± 6.7% V̇O_2peak (16.9 ± 4.2 ml kg^-1 min^-1), and 29.4 ± 7.7% of the session was spent at or above 80% V̇O_2peak. During HIIE working phase, RER declined from the first to last interval (1.08 ± 0.07 vs 0.98 ± 0.09; p < 0.001), reflecting an initially high but declining glycolytic rate.

CONCLUSIONS

Compared with MICE, HIIE imposed a greater physiological stimulus while requiring less time to achieve a target caloric expenditure. Thus, exercise intensity might be an important consideration in the tailoring of exercise prescription to address the cardiometabolic comorbidities of SCI.

Guideline Approaches for Cardioendocrine Disease Surveillance and Treatment Following Spinal Cord Injury

PURPOSE OF REVIEW

Persons with spinal cord injuries (SCI) commonly experience individual risks and coalesced health hazards of the cardiometabolic syndrome (CMS). This review will examinethe role of exercise and nutritional intervention as countermeasures to these disease risks.

RECENT FINDINGS

The CMS hazards of overweight/obesity, insulin resistance, hypertension, and dyslipidemia are strongly associated with physical deconditioning and are common after SCI. Both the CMS diagnosis and physical deconditioning worsen the prognosis for all-cause cardiovascular disease occurring early after SCI. Evidence supports a therapeutic role for physical activity after SCI as an effective countermeasure to these risks and often represents the first-line approach to CMS abatement. This evidence is supported by authoritative systematic reviews and associated guidelines that recommend specific activities, frequencies, and activities of work. In many cases, the most effective exercise programming uses more intense periods of work with limited rest. As SCI is also associated with poor dietary habits, including excessive energy intake and saturated fat consumption, more comprehensive lifestyle management incorporating both exercise and nutrition represents a preferred approach for overall health management.

SUMMARY

Irrespective of the interventional strategy, improved surveillance of the population for CMS risks and encouraged incorporation of exercise and nutritional management according to recent population-specific guidelines will most likely play an important role in the preservation of activity, optimal health, and independence throughout the lifespan.