• Penetration-Aspiration Scale [PAS] [ Time Frame: Pre-treatment baseline, 4 weeks after baseline, 8 weeks after baseline ]
  Change in swallowing safety on thin and mildly thick liquid swallows. The maximum PAS score per consistency will be collected.
• Number of swallows per bolus [ Time Frame: Pre-treatment baseline, 4 weeks after baseline, 8 weeks after baseline ]
  Change in swallowing efficiency on thin and mildly thick liquid swallows. The maximum number of swallows per bolus for each consistency will be collected.
• Pixel-based measurement of post-swallow pharyngeal residue [ Time Frame: Pre-treatment baseline, 4 weeks after baseline, 8 weeks after baseline ]
  Change in swallowing efficiency on thin and mildly thick liquid swallows measured as a % of the C2-C4-squared anatomical reference scalar. The highest value across repeated boluses within a consistency will be collected.
• International Dysphagia Diet Standardisation Initiative Functional Diet Scale [ Time Frame: Pre-treatment baseline, 4 weeks after baseline, 8 weeks after baseline ]
  Change in diet texture recommendation (number of diet texture levels allowed from the International Dysphagia Diet Standardisation Initiative Framework).

• Tongue Strength [ Time Frame: Pre-treatment baseline, 4 weeks after baseline, 8 weeks after baseline ]
  Change in maximum isometric tongue pressure, measured using the Iowa Oral performance Instrument. The maximum value of 3 repetitions will be collected.
• Saliva Swallow Tongue Pressures [ Time Frame: Pre-treatment baseline, 4 weeks after baseline, 8 weeks after baseline ]
  Change in saliva swallowing pressures, measured using the Iowa Oral Performance Instrument. the maximum value of 3 repetitions will be collected.
• Swallow Timing Swallow Timing [ Time Frame: Pre-treatment baseline, 4 weeks after baseline, 8 weeks after baseline ]
  Change in the timing of the hyoid burst onset and time to laryngeal vestibule closure, in milliseconds relative to the frame of the bolus passing the ramus of mandible, during thin and mildly thick liquid swallows measured on videofluoroscopy. The maximum value per consistency will be collected.
• Hyoid Kinematics [ Time Frame: Pre-treatment baseline, 4 weeks after baseline, 8 weeks after baseline ]
  Change in peak hyoid position (in anatomically normalized units of distance relative to the C2-C4 reference scalar) during thin and mildly thick liquid swallows measured on videofluoroscopy. The maximum value per consistency will be collected.
• Pharyngeal constriction [ Time Frame: Pre-treatment baseline, 4 weeks after baseline, 8 weeks after baseline ]
  Change in pharyngeal constriction (measured as a % of the C2-C4-squared reference scalar) during thin and mildly thick liquid swallows measured on videofluoroscopy. The best (i.e. smallest) value per consistency will be collected.

• Tongue Strength [ Time Frame: Pre-treatment baseline, 4 weeks after baseline, 8 weeks after baseline ]
  Change in maximum isometric tongue pressure, measured using the Iowa Oral performance Instrument. The maximum value of 3 repetitions will be collected.
• Saliva Swallow Tongue Pressures [ Time Frame: Pre-treatment baseline, 4 weeks after baseline, 8 weeks after baseline ]
  Change in saliva swallowing pressures, measured using the Iowa Oral Performance Instrument. the maximum value of 3 repetitions will be collected.
• Swallow Timing Swallow Timing [ Time Frame: Pre-treatment baseline, 4 weeks after baseline, 8 weeks after baseline ]
  Change in the timing of the hyoid burst onset and laryngeal vestibule closure, in milliseconds relative to the frame of the bolus passing the ramus of mandible, during thin and mildly thick liquid swallows measured on videofluoroscopy. The maximum value per consistency will be collected.
• Hyoid Kinematics [ Time Frame: Pre-treatment baseline, 4 weeks after baseline, 8 weeks after baseline ]
  Change in peak hyoid position (in anatomically normalized units of distance relative to the C2-C4 reference scalar) during thin and mildly thick liquid swallows measured on videofluoroscopy. The maximum value per consistency will be collected.
• Pharyngeal constriction [ Time Frame: Pre-treatment baseline, 4 weeks after baseline, 8 weeks after baseline ]
  Change in pharyngeal constriction (measured as a % of the C2-C4-squared reference scalar) during thin and mildly thick liquid swallows measured on videofluoroscopy. The best (i.e. smallest) value per consistency will be collected.

Swallowing dysfunction (dysphagia) following stroke results from damage to sensory and motor nerve pathways, impairing muscular physiology and impacting swallow timeliness and airway closure. People with dysphagia experience impaired swallowing safety (entry of food or liquid into the airway - aspiration) and/or impaired swallowing efficiency (food or liquid remaining in the oropharyngeal cavities after the swallow - residue). People with dysphagia following stroke are more likely to experience aspiration pneumonia, which has been associated with higher mortality rates.

The tongue functions to contain food and liquid within the oral cavity before the bolus moves into the pharynx. The tongue generates the primary driving forces, which carry the bolus through the pharynx; consequently, impairments in tongue function can affect both swallowing safety and efficiency. For people who have experienced a stroke, lingual strength is decreased compared to healthy participants. Tongue pressure resistance training has been utilized as an intervention in this population, and has been shown to positively influence tongue strength. It remains unclear whether changes in tongue pressure impact swallowing mechanisms, safety, and efficiency for patients who complete these interventions. In particular, the impact of tongue pressure resistance training on swallow timeliness (swallow onset timing, airway closure reaction time, speed of hyolaryngeal movement) remains unknown. This study will be a randomized trial of tongue pressure resistance training in people with tongue weakness and impaired swallowing safety post-stroke. The goal is to understand the physiological changes that occur as an outcome of tongue pressure resistance training and their relationship to swallowing safety and efficiency. Additionally, the impact of a training protocol involving a home practice component to delineate the impact of patient-driven practice will be explored.

A sample of approximately 40 patients will be enrolled. Participants will complete an 8-week program involving a 4-week course of tongue-pressure resistance training and a 4-week no-treatment phase. Participants will be randomized either to an immediate treatment group (followed by a 4-week post-treatment detraining phase) or to a delayed treatment group involving a 4-week waiting period prior to beginning training. Swallowing outcomes will be measured based on videofluoroscopic swallowing studies (VFSS) performed at baseline, 4-weeks and 8-weeks post enrollment. The tongue pressure resistance training program will involve practice of tongue-palate pressure generation tasks and swallowing tasks, with biofeedback provided using the Iowa Oral Performance Instrument (IOPI).

• Stroke
• Dysphagia

• Experimental: Immediate
  Participants in the immediate intervention arm will begin a 4-week intervention tongue pressure resistance training protocol within 10 days of their baseline Videofluoroscopic Swallowing Evaluation assessment, with 2 face-to-face 1-hour visits per week under direct supervision of a speech-language pathologist. These treatment sessions will be supplemented by daily home practice of the intervention.
  Intervention: Behavioral: Tongue Pressure Resistance Training
• Active Comparator: Delayed
  Participants in the delayed intervention arm will begin their involvement with a 4-week waiting period after the baseline Videofluoroscopic Swallowing Evaluation. Treatment will commence after the second Videofluoroscopic Swallowing Evaluation and will follow the same schedule for the tongue pressure resistance training, supplemented by daily home practice.
  Intervention: Behavioral: Tongue Pressure Resistance Training

• Cho YS, Oh DH, Paik YR, Lee JH, Park JS. Effects of bedside self-exercise on oropharyngeal swallowing function in stroke patients with dysphagia: a pilot study. J Phys Ther Sci. 2017 Oct;29(10):1815-1816. doi: 10.1589/jpts.29.1815. Epub 2017 Oct 21.
• Hori K, Ono T, Iwata H, Nokubi T, Kumakura I. Tongue pressure against hard palate during swallowing in post-stroke patients. Gerodontology. 2005 Dec;22(4):227-33.
• Kim HD, Choi JB, Yoo SJ, Chang MY, Lee SW, Park JS. Tongue-to-palate resistance training improves tongue strength and oropharyngeal swallowing function in subacute stroke survivors with dysphagia. J Oral Rehabil. 2017 Jan;44(1):59-64. doi: 10.1111/joor.12461.
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• McKenna VS, Zhang B, Haines MB, Kelchner LN. A Systematic Review of Isometric Lingual Strength-Training Programs in Adults With and Without Dysphagia. Am J Speech Lang Pathol. 2017 May 17;26(2):524-539. doi: 10.1044/2016_AJSLP-15-0051. Review.
• Park JS, Kim HJ, Oh DH. Effect of tongue strength training using the Iowa Oral Performance Instrument in stroke patients with dysphagia. J Phys Ther Sci. 2015 Dec;27(12):3631-4. doi: 10.1589/jpts.27.3631. Epub 2015 Dec 28.
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Inclusion Criteria:

• English-speaking adults
• A confirmed diagnosis of ischemic stroke (including hemispheric, cortical or subcortical and excluding cerebellum and brainstem locations within 3 months following the stroke) identified via CT or MRI
• Eligible participants will display decreased tongue pressure as measured by the Iowa Oral Performance Instrument (IOPI), and show evidence of dysphagia (safety or efficiency concerns) on baseline VFSS with thin or mildly thick liquid stimuli.

Exclusion Criteria:

• History of head and neck cancer
• Radical neck dissection (e.g. anterior cervical surgery fusions) or neck/ oropharyngeal surgery (not excluded - tonsillectomy, adenoidectomy, tracheostomy)
• Past medical history of any neurological disease other than stroke (e.g. Multiple Sclerosis, Parkinson Disease, Amyotrophic Lateral Sclerosis, Traumatic Brain Injury)
• Oral apraxia, impairing the participant's ability to complete exercises
• Cognitive or receptive communication difficulties that preclude the participant's ability to follow study instructions
• Allergies to barium, potato starch, corn starch, xanthan gum, milk products, or latex