A Phase 1 interventional study of Biomotum Spark: Robotic ankle assistance and Biomotum Spark: Robotic ankle resistance in Cerebral Palsy, sponsored by Northern Arizona University. Recruiting at 1 site in United States. Open to participants aged 8 Years to 21 Years. Per ClinicalTrials.gov, last updated 2026-03-03.
Sponsored by Northern Arizona University · Phase 1, Interventional, and Treatment
The first specific aim is to quantify improvement in ankle muscle function and functional mobility following targeted ankle resistance gait training in ambulatory children with cerebral palsy (CP). The primary hypothesis for the first aim is that targeted ankle resistance training will produce larger improvements in lower-extremity motor control, gait mechanics, and clinical measures of mobility assessed four- and twelve-weeks post intervention compared to standard physical therapy and standard gait training. The second specific aim is to determine the efficacy of adaptive ankle assistance to improve capacity and performance during sustained, high-intensity, and challenging tasks in ambulatory children with CP. The primary hypothesis for the second aim is that adaptive ankle assistance will result in significantly greater capacity and performance during the six-minute-walk-test and graded treadmill and stair stepping protocols compared to walking with ankle foot orthoses and walking with just shoes.
A child's ability to walk effectively is essential to their physical health and general well-being. Unfortunately, many children with cerebral palsy (CP), the most common cause of pediatric physical disability, have difficulty walking and completing higher-intensity ambulatory tasks. This leads to children with CP engaging in levels of habitual physical activity that are well below guidelines and those of children without disabilities, which in turn contributes to many secondary conditions, including metabolic dysfunction and cardiovascular disease. There is broad clinical consensus that plantarflexor dysfunction is a primary contributor to slow, inefficient, and crouched walking patterns in CP; individuals with CP need more effective treatments and mobility aids for plantarflexor dysfunction. To meet this need, this proposal aims to evaluate a holistic strategy to address impaired mobility from plantarflexor dysfunction in CP using a lightweight, dual-mode (assistive or resistive) wearable robotic device. This strategy combines two complementary techniques: (1) targeted ankle resistance for neuromuscular gait training that provides precision therapy to elicit long-term improvements in ankle muscle function, and (2) adaptive ankle assistance to make walking easier during sustained, high-intensity, or challenging tasks.
Aim 1: Quantify improvement in ankle muscle function and functional mobility following targeted ankle resistance gait training in ambulatory children with CP Approach - Repeated Measures (RM) and randomized controlled trial: The investigators will compare functional outcomes following targeted ankle resistance training (2 visits/week for 12 weeks) vs. dose-matched standard physical therapy (RM) and vs. dose-matched standard treadmill training (randomized controlled trial). Primary Hypothesis: Targeted ankle resistance training will produce larger improvements in lower-extremity motor control, gait mechanics, and clinical measures of mobility assessed four- and twelve-weeks post intervention compared to the control conditions.
Aim 2: Determine the efficacy of adaptive ankle assistance to improve capacity and performance during sustained, high-intensity, and challenging tasks in ambulatory children with CP Approach - Repeated Measures: The investigators will compare task capacity and performance with adaptive ankle assistance vs. standard ankle foot orthoses and vs. shod (no ankle aid) during (a) 6-minute-walk-test, (b) extended-duration over-ground walking (sustained), (c) graded treadmill (high-intensity), and (d) stair-stepping (challenging) protocols. Task capacity and performance will be measured by duration, metabolic cost, speed, and stride length, as applicable. Primary Hypothesis: Adaptive ankle assistance will result in significantly greater capacity and performance compared to the control conditions.
Exclusion Criteria:
We will conduct a randomized controlled trial (treatment vs. control) to compare functional outcomes following bilateral targeted ankle resistance training (2 visits/week for 12 weeks) vs. dose-matched standard functional gait training.
Device: Biomotum Spark: Robotic ankle resistance
We will conduct a randomized controlled trial (treatment vs. control) to compare functional outcomes following bilateral targeted ankle resistance training (2 visits/week for 12 weeks) vs. dose-matched standard functional gait training.
Other: Standard gait training
We will use a within-subject repeated measures design to compare both gait training groups to matched standard physical therapy.
Other: Standard physical therapy
We will compare task capacity and performance with adaptive ankle assistance vs. standard ankle foot orthoses and vs. shod (no ankle aid).
Device: Biomotum Spark: Robotic ankle assistance
We will compare task capacity and performance with adaptive ankle assistance vs. standard ankle foot orthoses and vs. shod (no ankle aid).
Device: Ankle foot orthosis
We will compare task capacity and performance with adaptive ankle assistance vs. standard ankle foot orthoses and vs. shod (no ankle aid).
Other: Standard walking
A lightweight assistive wearable ankle robotic device.
A lightweight resistive wearable ankle robotic device.
Standard gait training without a device.
Standard ankle foot orthosis
Physical therapy without a device.
Walking without a device
Change in preferred walking speed
Participant's preferred walking speed compared after to before the intervention
Time frame: Immediately after the intervention
Change in preferred walking speed
Participant's preferred walking speed compared after to before the intervention
Time frame: 2 weeks after the intervention
Change in preferred walking speed
Participant's preferred walking speed compared after to before the intervention
Time frame: 12 weeks after the intervention
Change in similarity of plantarflexor muscle activity
Similarity of the plantarflexor muscle activity profile across the gait cycle, measured using surface electromyography (the measurement tool) of the soleus muscle, to the average unimpaired electromyography muscle activity profile, as calculated via cross-correlation coefficient. A higher value indicates greater similarity.
Time frame: Immediately after the intervention
Change in similarity of plantarflexor muscle activity
Similarity of the plantarflexor muscle activity profile across the gait cycle, measured using surface electromyography (the measurement tool) of the soleus muscle, to the average unimpaired electromyography muscle activity profile, as calculated via cross-correlation coefficient. A higher value indicates greater similarity.
Time frame: 2 weeks after the intervention
Change in similarity of plantarflexor muscle activity
Similarity of the plantarflexor muscle activity profile across the gait cycle, measured using surface electromyography (the measurement tool) of the soleus muscle, to the average unimpaired electromyography muscle activity profile, as calculated via cross-correlation coefficient. A higher value indicates greater similarity.
Time frame: 12 weeks after the intervention
Change in 6-minute-walk-test distance
Distance traveled in 6 minutes during a 6-minute-walk-test protocol. A longer distance indicates greater walking capacity.
Time frame: Immediately after the intervention
Change in 6-minute-walk-test distance
Distance traveled in 6 minutes during a 6-minute-walk-test protocol. A longer distance indicates greater walking capacity.
Time frame: 2 weeks after the intervention
Change in 6-minute-walk-test distance
Distance traveled in 6 minutes during a 6-minute-walk-test protocol. A longer distance indicates greater walking capacity.
Time frame: 12 weeks after the intervention
Change in variance in muscle activity
Variance in muscle activity accounted for by one muscle synergy assessed using surface electromyography (the measurement tool) of the soleus, tibialis anterior, medial hamstrings, and vastus medialis. Muscle synergies will be computed from non-negative matrix factorization. Lower variance accounted for by one muscle synergy indicates a desired greater complexity of motor control.
Time frame: Immediately after the intervention
Change in variance in muscle activity
Variance in muscle activity accounted for by one muscle synergy assessed using surface electromyography (the measurement tool) of the soleus, tibialis anterior, medial hamstrings, and vastus medialis. Muscle synergies will be computed from non-negative matrix factorization. Lower variance accounted for by one muscle synergy indicates a desired greater complexity of motor control.
Time frame: 2 weeks after the intervention
Change in variance in muscle activity
Variance in muscle activity accounted for by one muscle synergy assessed using surface electromyography (the measurement tool) of the soleus, tibialis anterior, medial hamstrings, and vastus medialis. Muscle synergies will be computed from non-negative matrix factorization. Lower variance accounted for by one muscle synergy indicates a desired greater complexity of motor control.
Time frame: 12 weeks after the intervention
Change in stride length
Participant stride length during walking. Longer stride length is desired.
Time frame: Immediately after the intervention
Change in stride length
Participant stride length during walking. Longer stride length is desired.
Time frame: 2 weeks after the intervention
Change in stride length
Participant stride length during walking. Longer stride length is desired.
Time frame: 12 weeks after the intervention
Change in stride-to-stride variability stride length
Stride-to-stride variability of lower-extremity muscle activity for the soleus, tibias anterior, vastus lateralis, and medial hamstrings, measured via surface electromyography and calculated as the variance ratio across strides.
Time frame: Immediately after the intervention
Change in stride-to-stride variability stride length
Stride-to-stride variability of lower-extremity muscle activity for the soleus, tibias anterior, vastus lateralis, and medial hamstrings, measured via surface electromyography and calculated as the variance ratio across strides.
Time frame: 2 weeks after the intervention
Change in stride-to-stride variability stride length
Stride-to-stride variability of lower-extremity muscle activity for the soleus, tibias anterior, vastus lateralis, and medial hamstrings, measured via surface electromyography and calculated as the variance ratio across strides.
Time frame: 12 weeks after the intervention
Change in walking posture
Peak Lower-extremity joint angles summed across the ankle, knee, and hip joints, measured using motion capture (the measurement tool).
Time frame: Immediately after the intervention
Change in walking posture
Peak Lower-extremity joint angles summed across the ankle, knee, and hip joints, measured using motion capture (the measurement tool).
Time frame: 2 weeks after the intervention
Change in walking posture
Peak Lower-extremity joint angles summed across the ankle, knee, and hip joints, measured using motion capture (the measurement tool).
Time frame: 12 weeks after the intervention
Change in Gross Motor Function Measure-66 sec. D&E
Gross Motor Function Measure - 66, sections (D) standing, and (E) walking, running and jumping. Higher scores are better, and range from 0-3 for each measure.
Time frame: Immediately after the intervention
Change in Gross Motor Function Measure-66 sec. D&E
Gross Motor Function Measure - 66, sections (D) standing, and (E) walking, running and jumping. Higher scores are better, and range from 0-3 for each measure.
Time frame: 2 weeks after the intervention
Change in Gross Motor Function Measure-66 sec. D&E
Gross Motor Function Measure - 66, sections (D) standing, and (E) walking, running and jumping. Higher scores are better, and range from 0-3 for each measure.
Time frame: 12 weeks after the intervention
Change in plantar-flexor strength
Plantar-flexor muscle strength measured via hand-held dynamometry.
Time frame: Immediately after the intervention
Change in plantar-flexor strength
Plantar-flexor muscle strength measured via hand-held dynamometry.
Time frame: 2 weeks after the intervention
Change in plantar-flexor strength
Plantar-flexor muscle strength measured via hand-held dynamometry.
Time frame: 12 weeks after the intervention
Distance traveled
Distance traveled during the 6-minute-walk-test, and treadmill and stair stepper bruce protocols.
Time frame: 1 day
Metabolic cost of transport from indirect calorimetry
Metabolic cost estimated from a wearable indirect calorimetry system during the 6-minute-walk-test, and treadmill and stair stepper bruce protocols
Time frame: 1 day
Subject perceived exertion
Subject perceived exertion (validated pictorial pediatric exertion scale). The scale is from 1-10, where a higher number indicates more effort.
Time frame: 1 day
Average muscle activity
Average stance-phase plantar flexor muscle activity assessed through surface electromyography of the soleus muscle.
Time frame: 1 day
Heart Rate
Average heart rate during each testing condition measured via chest-mounted heart rate monitor.
Time frame: 1 day
Documents are hosted by the registry — open the source record to download them.
Plan to share: No
Eligibility is decided by the study team. Share this record with your doctor or contact the team directly.
Contact study teamGet an email when the registry record changes — status, dates, results — or when someone posts here.
Sign in to followQuestions and observations about this study, from anyone following it. Not medical advice, and not a channel to the study team — their contact details are on the registry record.
Sign in to join the discussion. Reading takes no account; posting does. You choose a display name, and a pseudonym is the default.
Nothing here yet. If you are running this trial, taking part in it, or weighing whether to, this is the place to say so.
Northern Arizona University