Synergy between Acute Intermittent Hypoxia and Task-Specific Training

Welch, Joseph F.; Sutor, Tommy W.; Vose, Alicia; Perim, Raphael R.; Fox, Emily J.; Mitchell, Gordon S.

doi:10.1249/jes.0000000000000222

Cited by 29 publications

(15 citation statements)

References 51 publications

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“…Identification of novel therapies that harness the intrinsic capacity of the CNS for plasticity are of paramount importance (Randelman et al., 2021; Vose et al., 2022). Moreover, when combined with task‐specific respiratory training, AIHH effects may be synergistic (Welch, Sutor et al., 2020), further increasing the potential for recovery. Whether daily AIHH over a period of weeks or months enhances plasticity and/or increases the duration of sustained effects is not known and should be investigated.…”

Section: Discussionmentioning

confidence: 99%

Acute intermittent hypercapnic‐hypoxia elicits central neural respiratory motor plasticity in humans

Welch

Nair

Argento

et al. 2022

The Journal of Physiology

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Acute intermittent hypoxia (AIH) elicits long‐term facilitation (LTF) of respiration. Although LTF is observed when CO2 is elevated during AIH in awake humans, the influence of CO2 on corticospinal respiratory motor plasticity is unknown. Thus, we tested the hypotheses that acute intermittent hypercapnic‐hypoxia (AIHH): (1) enhances cortico‐phrenic neurotransmission (reflecting volitional respiratory control); and (2) elicits ventilatory LTF (reflecting automatic respiratory control). Eighteen healthy adults completed four study visits. Day 1 consisted of anthropometry and pulmonary function testing. On Days 2, 3 and 4, in a balanced alternating sequence, participants received: AIHH, poikilocapnic AIH, and normocapnic‐normoxia (Sham). Protocols consisted of 15, 60 s exposures with 90 s normoxic intervals. Transcranial (TMS) and cervical (CMS) magnetic stimulation were used to induce diaphragmatic motor‐evoked potentials and compound muscle action potentials, respectively. Respiratory drive was assessed via mouth occlusion pressure (P0.1), and minute ventilation measured at rest. Dependent variables were assessed at baseline and 30–60 min after exposures. Increases in TMS‐evoked diaphragm potential amplitudes were observed following AIHH vs. Sham (+28 ± 41%, P = 0.003), but not after AIH. No changes were observed in CMS‐evoked diaphragm potential amplitudes. Mouth occlusion pressure also increased after AIHH (+21 ± 34%, P = 0.033), but not after AIH. Ventilatory LTF was not observed after any treatment. We demonstrate that AIHH elicits central neural mechanisms of respiratory motor plasticity and increases resting respiratory drive in awake humans. These findings may have important implications for neurorehabilitation after spinal cord injury and other neuromuscular disorders compromising breathing. Key points The occurrence of respiratory long‐term facilitation following acute exposure to intermittent hypoxia is believed to be dependent upon CO2 regulation – mechanisms governing the critical role of CO2 have seldom been explored. We tested the hypothesis that acute intermittent hypercapnic‐hypoxia (AIHH) enhances cortico‐phrenic neurotransmission in awake healthy humans. The amplitude of diaphragmatic motor‐evoked potentials induced by transcranial magnetic stimulation was increased after AIHH, but not the amplitude of compound muscle action potentials evoked by cervical magnetic stimulation. Mouth occlusion pressure (P0.1, an indicator of neural respiratory drive) was also increased after AIHH, but not tidal volume or minute ventilation. Thus, moderate AIHH elicits central neural mechanisms of respiratory motor plasticity, without measurable ventilatory long‐term facilitation in awake humans.

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Section: Discussionmentioning

confidence: 99%

Acute intermittent hypercapnic‐hypoxia elicits central neural respiratory motor plasticity in humans

Welch

Nair

Argento

et al. 2022

The Journal of Physiology

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“…Despite improvements in therapeutic modalities over time, no single therapy has proven to be overly effective for overcoming these impairments. The combination of task-specific training modalities coupled with neuromodulation approaches is most likely to have the greatest impact on functional recovery 1,2 . Mild doses of acute intermittent hypoxia (AIH), which consist of repeated but brief periods of breathing low oxygen gas mixtures, has gained attention in recent decades due to its facilitatory effects on respiratory and non-respiratory motor function 2,3 .…”

Section: Introductionmentioning

confidence: 99%

Acute intermittent hypoxia enhances volitional elbow strength, and modulates spatial distribution of muscle activation patterns in persons with chronic incomplete spinal cord injury

Afsharipour

Pearcey

Rymer

et al. 2022

Preprint

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Background: Acute intermittent hypoxia (AIH) is an emerging technique for facilitating neural plasticity in individuals with major neurological deficits. In people with chronic incomplete spinal cord injury (iSCI), a single sequence of AIH enhances motor function such as hand grip strength and ankle plantarflexion torque, but the underlying mechanisms are not yet clear. Objective: To examine how AIH-induced changes in magnitude and spatial distribution of electromyography (EMG) activity over the surface of the biceps and triceps brachii muscles contributes to improved strength. Methods: Seven individuals with iSCI visited the laboratory on two occasions, at least a week apart, and received either AIH or Sham AIH intervention in a randomized order. AIH consisted of 15 brief (~60s) periods of low oxygen (fraction of inspired O2 = 0.09) alternating with 60s of normoxia, whereas Sham AIH consisted of repeated exposures to normoxic gas mixtures. Muscle activity of biceps and triceps brachii was recorded with high-density surface EMG during maximal elbow flexion and extension contractions. We used these EMG recordings to generate spatial maps which distinguished active muscle regions prior to and 60 minutes after AIH or Sham AIH. Results: After an AIH sequence, elbow flexion and extension forces increased by 91.7 +/- 33.5% and 51.7 +/- 21.9% from baseline, respectively, whereas there was no difference after Sham AIH exposure. Changes in strength were associated with an altered spatial distribution of EMG activity and increased root mean squared EMG amplitude in both biceps and triceps brachii muscles. Conclusions: These data suggest that altered motor unit activation profiles may underlie improved volitional strength after a single dose of AIH and warrant further investigation using single motor unit analysis techniques to further elucidate mechanisms of AIH-induced plasticity.

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“… 104 - 106 Because intermittent hypoxia also facilitates release of 5-HT, at least to the cervical phrenic motor nuclei, it would likely have additive benefits to other therapies discussed here. 108 …”

Section: Emerging Therapiesmentioning

confidence: 99%

Developing Peri-Operative Rehabilitation in Degenerative Cervical Myelopathy [AO Spine RECODE-DCM Research Priority Number 6]: An Unexplored Opportunity?

Boerger

Hyngstrom

Furlan

et al. 2022

Global Spine Journal

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Study Design Narrative review. Objective Degenerative cervical myelopathy is one of the most frequent impairments of the spinal cord encountered internationally in adults. Currently, surgical decompression is the recommended treatment for people with DCM (PwCM) presenting with moderate to severe symptoms or neurological deficits. However, despite surgical intervention, not all patients make a complete recovery due to the irreversible tissue damage within the spinal cord. The objective of this review is to describe the state and gaps in the current literature on rehabilitation for PwCM and possible innovative rehabilitation strategies. Methods Literature search. Results In other neurological disorders such as stroke and acute traumatic spinal cord injury (SCI), timely and strategic rehabilitation has been shown to be indispensable for maximizing functional outcomes, and it is imperative that appropriate perioperative rehabilitative interventions accompany surgical approaches in order to enable the best outcomes. In this review, the current state of knowledge regarding rehabilitation for PwCM is described. Additionally, various therapies that have shown to improve outcomes in comparable neurological conditions such as stroke and SCI which may be translated to DCM will be reviewed. Conclusions We conclude that locomotor training and arm/hand therapy may benefit PwCM. Further, we conclude that body weight support, robotic assistance, and virtual/augmented reality therapies may be beneficial therapeutic analogs to locomotor and hand therapies.

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Synergy between Acute Intermittent Hypoxia and Task-Specific Training

Cited by 29 publications

References 51 publications

Acute intermittent hypercapnic‐hypoxia elicits central neural respiratory motor plasticity in humans

Acute intermittent hypercapnic‐hypoxia elicits central neural respiratory motor plasticity in humans

Acute intermittent hypoxia enhances volitional elbow strength, and modulates spatial distribution of muscle activation patterns in persons with chronic incomplete spinal cord injury

Developing Peri-Operative Rehabilitation in Degenerative Cervical Myelopathy [AO Spine RECODE-DCM Research Priority Number 6]: An Unexplored Opportunity?

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