This pilot study will compare a yoga program to a non-yoga exercise program in adults with brain injuries. The investigators will measure possible improvements in balance and heartrate. The investigators also plan to measure changes in brain function and link balance and/or heartrate improvements to changes in brain function. Ideally, this work will create a foundation for a larger-scale study.

Background and Significance: Each year, an estimated 2.9 million Americans sustain brain injuries that result in emergency department visits, hospitalizations, and death. Although there are many treatment strategies in the early weeks and months after brain injury, millions of individuals live with residual disability. This residual, chronic disability often includes significant impairments and decreased brain function. Two prominent and interconnected impairments - poor balance and autonomic nervous system (ANS) dysfunction - can increase fall risk, decrease quality of life, and increase mortality. In adults with brain injury, ANS dysfunction is characterized by hyper-activation of the sympathetic nervous system, which can have damaging or even fatal impact on internal organs. To date, there are exceedingly few options for addressing these types of impairments or improving brain function in adults with chronic brain injury. However, community-based and holistic interventions, like hatha yoga, may be highly effective for simultaneously addressing balance and ANS impairments and may also improve brain function. Hatha yoga incorporates movements that improve balance, uses breathwork that may stabilize sympathetic and parasympathetic nervous system activity, can be adapted for individual needs, and has enhanced brain function in healthy adults. Despite this, there are few empirical studies investigating yoga for individuals with brain injury. To resolve this, the research team and investigator have conducted two yoga and brain injury feasibility studies and confirmed that recruitment, retainment, intervention, and neuroimaging procedures are feasible. In these studies, the investigators have found significant improvements in balance after yoga and preliminary evidence of improved brain function, even in the absence of measurable balance improvement. Finally, there is growing evidence that exercises, like yoga, can improve ANS function by regulating sympathetic and parasympathetic activity in healthy adults, suggesting significant potential for adults with chronic brain injury.

Project Objectives: Given feasibility study success and promising early findings. The investigators will conduct a pilot randomized control trial comparing 8-weeks of group yoga to 8-weeks of active control exercise in 48 adults with chronic brain injury. The investigators will test for improvements in balance and in ANS function using heart-rate variability (HRV) monitoring. The investigator will explore intervention-induced changes in brain function by evaluating intrinsic functional connectivity, using resting-state functional magnetic resonance imaging (rs-fMRI) and task-dependent neural activation, using a proxy of neural activity - oxygenated hemoglobin (HbO) - as measured with functional near-infrared spectroscopy (fNIRS) during concurrent balance tasks. Finally, if the investigators observe functional improvements in balance or ANS function and measurable changes in brain function, the investigator will then complete exploratory analyses to link functional improvements to changes in brain function.

Inclusion Criteria:

• Sustained acquired brain injury at least 6 months prior
• Self-reported balance impairment of moderate or greater, via the Neurobehavioral Symptom Inventory
• Standard fMRI safety screening for MRI components only (participants can complete other study components if they are ineligible or unwilling to complete MRI)

Exclusion Criteria:

• Sustained acquired brain injury within past 6 months
• Self-reported mild balance impairment or no balance impairment

Ideally, we will upload de-identified participant data into a public repository. We are in the process of hiring and training personnel who can fulfill this role.

The principal investigator and postdoctoral fellow are exclusively responsible for assessing outcomes and both are masked to participant group membership. The participants, interventionists, and other key persons are not masked to participant group membership, but they are not involved in any of the outcome assessments.