Inefficient skeletal muscle oxidative function flanks impaired motor neuron recruitment in Amyotrophic Lateral Sclerosis during exercise

Lowered oxidative capacity in spinal muscular atrophy, Jokela type; comparison with mitochondrial muscle disease

Introduction

Spinal muscular atrophy, Jokela type (SMAJ) is a rare autosomal dominantly hereditary form of spinal muscular atrophy caused by a point mutation c.197G>T in CHCHD10. CHCHD10 is known to be involved in the regulation of mitochondrial function even though patients with SMAJ do not present with multiorgan symptoms of mitochondrial disease. We aimed to characterize the cardiopulmonary oxidative capacity of subjects with SMAJ compared to healthy controls and patients with mitochondrial myopathy.

Methods

Eleven patients with genetically verified SMAJ, 26 subjects with mitochondrial myopathy (MM), and 28 healthy volunteers underwent a cardiopulmonary exercise test with lactate and ammonia sampling. The effect of the diagnosis group on the test results was analysed using a linear model.

Results

Adjusted for sex, age, and BMI, the SMAJ group had lower power output (p < 0.001), maximal oxygen consumption (VO2 max) (p < 0.001), and mechanical efficiency (p < 0.001) compared to the healthy controls but like that in MM. In the SMAJ group and healthy controls, plasma lactate was lower than in MM measured at rest, light exercise, and 30 min after exercise (p ≤ 0.001-0.030) and otherwise lactate in SMAJ was lower than controls and MM, in longitudinal analysis p = 0.018. In MM, the ventilatory equivalent for oxygen was higher (p = 0.040), and the fraction of end-tidal CO2 lower in maximal exercise compared to healthy controls (p = 0.023) and subjects with SMAJ.

Conclusion

In cardiopulmonary exercise test, subjects with SMAJ showed a similar decrease in power output and oxidative capacity as subjects with mitochondrial myopathy but did not exhibit findings typical of mitochondrial disease.

Cardiopulmonary exercise testing in neuromuscular disease: a systematic review

INTRODUCTION

Cardiopulmonary exercise testing (CPET) is increasingly used to determine aerobic fitness in health and disability conditions. Patients with neuromuscular diseases (NMDs) often present with symptoms of cardiac and/or skeletal muscle dysfunction and fatigue that might impede the ability to deliver maximal cardiopulmonary effort. Although an increasing number of studies report on NMDs' physical fitness, the applicability of CPET remains largely unknown.

AREAS COVERED

This systematic review synthesized evidence about the quality and feasibility of CPET in NMDs and patient's aerobic fitness. The review followed the PRISMA guidelines (PROSPERO number CRD42020211068). Between September and October 2020 one independent reviewer searched the PubMed/MEDLINE, EMBASE, SCOPUS, and Web of Science databases. Excluding reviews and protocol description articles without baseline data, all study designs using CPET to assess adult or pediatric patients with NMDs were included. The methodological quality was assessed according to the American Thoracic Society/American College of Chest Physicians (ATS/ACCP) recommendations.

EXPERT OPINION

CPET is feasible for ambulatory patients with NMDs when their functional level and the exercise modality are taken into account. However, there is still a vast potential for standardizing and designing disease-specific CPET protocols for patients with NMDs. Moreover, future studies are urged to follow the ATS/ACCP recommendations.

A Case Report on Robot-Aided Gait Training in Primary Lateral Sclerosis Rehabilitation: Rationale, Feasibility and Potential Effectiveness of a Novel Rehabilitation Approach

Primary lateral sclerosis (PLS) is an adult-onset idiopathic disorder of the upper motor neuron system. Robot-aided rehabilitation with the Lokomat-Pro (LT) allows maximizing motor training by finely and individually controlling motor activation. No data are currently available on the use of robot-aided rehabilitation in PLS. The aim of this case study was to evaluate the effectiveness of a customized robotic rehabilitation protocol in PLS. A 54-year-old woman, diagnosed with PLS five years before admission, came to our clinic to undergo rehabilitation training due to gait difficulties with spastic paraparesis. The patient was treated with two different approaches: conventional physiotherapy followed by a combined approach (i.e. PT plus LT). After the conventional PT rehabilitation, no significant functional improvement was noted. However, the combined approach led to a significant improvement in functional motor skills, including walking, balance and lower limb muscle strength, and spasticity. Our experimental training combining robot-aided and conventional rehabilitation could be a promising approach to mitigate the PLS disability burden.

Skeletal Muscle in ALS: An Unappreciated Therapeutic Opportunity?

Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disorder characterized by the selective degeneration of upper and lower motor neurons and by the progressive weakness and paralysis of voluntary muscles. Despite intense research efforts and numerous clinical trials, it is still an incurable disease. ALS had long been considered a pure motor neuron disease; however, recent studies have shown that motor neuron protection is not sufficient to prevent the course of the disease since the dismantlement of neuromuscular junctions occurs before motor neuron degeneration. Skeletal muscle alterations have been described in the early stages of the disease, and they seem to be mainly involved in the “dying back” phenomenon of motor neurons and metabolic dysfunctions. In recent years, skeletal muscles have been considered crucial not only for the etiology of ALS but also for its treatment. Here, we review clinical and preclinical studies that targeted skeletal muscles and discuss the different approaches, including pharmacological interventions, supplements or diets, genetic modifications, and training programs.

Tailored Exercise Training Counteracts Muscle Disuse and Attenuates Reductions in Physical Function in Individuals With Amyotrophic Lateral Sclerosis

Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disease, characterized by the progressive loss of motor neurons, which leads to a reduction in strength and exercise capacity. Although the concept of “Exercise is Medicine” is accepted for many diseases, the role of exercise in individuals with ALS is still debated. The aim of this study was to propose a tailored exercise training program that was both safe and effective for individuals with ALS, and to evaluate the effects of this combined, moderate-intensity, aerobic and strength training program on aerobic capacities, strength, and physical function. Sixteen individuals with ALS were randomly assigned to either a training (three times a week for 12 weeks; TRAIN, n = 8) or usual care (continued their usual standard of care and served as control; UC, n = 8) group. Peak power, peak oxygen uptake, as well as the gas exchange threshold (GET) during a cardiopulmonary exercise test (CPET) on a cycle ergometer, and the maximal strength (1RM) of the knee extensor muscles, were evaluated before and after 12 weeks. Participants also performed the “Timed Up and Go” (TUG) and the “6-min walking” (6MWT) tests. The ALS Functional Rating Scale revisited (ALSFRS-R), the ALS Severity Scale (ALS-SS), and the McGill quality of life (QoL) questionnaire were also measured. The GET increased from 0.94 ± 0.08 to 1.06 ± 0.10 L min^–1 in TRAIN (p = 0.009) and decreased from 0.79 ± 0.17 to 0.72 ± 0.17 L min^–1 in UC (p = 0.001). There was a significant difference between groups for changes in TUG (9.1 ± 5.5% improvement in TRAIN and 56.8 ± 18.5% worsening in UC, p = 0.002), ALSFRS-R (4.7 ± 2.6% decrease in TRAIN and 23.0 ± 5.6% decrease in UC, p = 0.007), and for the ALS-SS (2.2 ± 2.1% decrease in TRAIN and 12.4 ± 4.4% decrease in UC, p = 0.04). Even if the 1RM of the knee-extensor muscles showed a tendency to increase in TRAIN (70.1 ± 30.0%, p = 0.07), there was not a statistically significant difference (p = 0.57) with respect to the changes in the UC group (44.9 ± 20.7% increase, p = 0.11). This study showed that a combined moderate-intensity aerobic and strength training program, tailored to the physical capacities of each individual, can improve aerobic fitness and maintain physical function in individuals with ALS.

The Peripheral Nervous System in Amyotrophic Lateral Sclerosis: Opportunities for Translational Research

Although amyotrophic lateral sclerosis (ALS) has been considered as a disorder of the motor neuron (MN) cell body, recent evidences show the non-cell-autonomous pathogenic nature of the disease. Axonal degeneration, loss of peripheral axons and destruction of nerve terminals are early events in the disease pathogenic cascade, anticipating MN degeneration, and the onset of clinical symptoms. Therefore, although ALS and peripheral axonal neuropathies should be differentiated in clinical practice, they also share damage to common molecular pathways, including axonal transport, RNA metabolism and proteostasis. Thus, an extensive evaluation of the molecular events occurring in the peripheral nervous system (PNS) could be fundamental to understand the pathogenic mechanisms of ALS, favoring the discovery of potential disease biomarkers, and new therapeutic targets.

Impact of Hanging Motionless in Harness on Respiratory and Blood Pressure Reflex Modulation in Mountain Climbers

Harness hang syncope (HHS) is a risk that specifically affects safety of harness users in mountain climbing.

Aims: To evaluate individual patterns of breathing resulting from deranged cardiovascular reflexes triggering a syncopal event when a mismatch between cerebral O₂ demand and supply is present.

Results: Forty healthy participants [aged 39.1 (8.2) years] were enrolled in a motionless suspension test while hanging in harness. Respiratory gas exchange values were analyzed to assess the pattern of breathing (EpInW_el, respiratory elastic power) and cardiovascular parameters were monitored (BP, blood pressure). Four participants experienced HHS after 30.0 (7.6) minutes, with an early manifestation of loss of control of both a sustainable EpInW_el and BP, starting after 10–12 minutes. Among the other participants, two different reactions were observed during suspension: (1) group G1 tolerated 32.7 (11.4) minutes of suspension by a favorable adaptation of the EpInW_el and BP parameters and (2) group G2 showed significantly shorter time of suspension 24.0 (10.4) minutes with unfavorable increase in EpInW_el and BP.

Conclusions: Greater resistance to HHS occurs in people developing less marked fluctuations of both respiratory and cardiovascular reflex responses. Conversely, wider fluctuations both in control of EpInW_el and BP were observed in the event of decreased suspension tolerance or in syncopal events.

High-frequency motor rehabilitation in amyotrophic lateral sclerosis: a randomized clinical trial

Objective

Exercise may be physically and psychologically important for people with ALS, especially in the earlier stages of the disease, and, as a consequence, current ALS clinical management includes individualized rehabilitation as part of multidisciplinary care because. However, while recent studies focused on which type of exercise is more indicated to ALS patients, there is no evidence at which frequency training sessions should be performed.

Methods

We performed an assessor blinded randomized clinical trial to investigate the superiority of two different frequencies of exercise on rate of progression in ALS. We enrolled 65 patients in two groups: intensive exercise regimen (IER, five sessions/week) versus usual exercise regimen (UER, two sessions/week). The primary aim was to assess if IER decreased disease progression, measured through Amyotrophic Lateral Sclerosis Functional Rating Scale‐Revised, with respect to UER. Secondary aims included assessment of adverse events, tracheostomy‐free survival, motor and respiratory functions, fatigue, quality of life and caregiver burden. Treatment regimen consisted for both groups of the same kind of exercise including aerobic training, endurance training, stretching or assisted active mobilization, differing for frequency of intervention.

Results

No significant changes in disease progression were found in patients under IER versus UER. At the end of the study, there were no significant differences between the two groups in survival, respiratory function, time to supporting procedures, and quality of life. Adverse events, fatigue, and caregiver burden were not different between the two treatment regimens.

Conclusions

Despite some limitations, our trial demonstrated that high‐frequency physical exercise was not superior to UER on ALSFRS‐R scores, motor and respiratory functions, survival, fatigue, and quality of life of ALS patients.

The Role of Moderate Aerobic Exercise as Determined by Cardiopulmonary Exercise Testing in ALS

Introduction

The efficacy of cardiopulmonary exercise testing (CPET) to determining exercise intensity has not been established in Amyotrophic Lateral Sclerosis (ALS). We studied this intervention.

Methods

We included 48 ALS patients randomized in 2 groups: G1 (n = 24), exercise intensity leveled by CPET; G2 (n = 24), standard care limited by fatigue, during 6 months. ALS functional scale (ALSFRS-R) and forced vital capacity (FVC) were performed every 3 months; CPET was done at admission (T1) and 6 months later (T2). We registered oxygen uptake, carbon dioxide output, and ventilation at anaerobic threshold and at peak effort. Primary outcome was functional change. We used parametric statistics for comparisons and multiple regression analyses to identify independent predictors of functional decline.

Results

At T1 both groups were identical, except for higher FVC in G1 (p = 0.02). At T2, ALSFRS-R was higher (p = 0.035) in G1. Gas exchange variables at T2 did not change in G1 but had significant differences in G2 (p < 0.05). Multiregression analyses showed the Spinal ALSFRS-R slope and Intervention group (p < 0.001) as significant predictors of ALSFRS-R at T2.

Conclusion

Aerobic exercise defined by CPET is feasible and can improve functional outcome in ALS. This trial is registered with Clinical trials.gov ID: NCT03326622.