Microgravity Treadmill Technology:
The Evidence Base
Lower Body Positive Pressure (LBPP) technology — developed by Dr. Robert Whalen at NASA Ames Research Center in the late 1980s and early 1990s, and brought to market by Boost Treadmills — is one of the most clinically versatile rehabilitation and performance tools in modern practice. Explore the complete peer-reviewed evidence base below.
Body Weight Percentage (BW%) Interactive Reference
BW% = the percentage of full body weight the user feels. Unloading = 100% minus BW%. Adjust to explore clinical applications. Boost Treadmills allow unloading up to 80% (user feels as little as 20% of their body weight).
(BW%)
(= 100% − BW%)
Clinical Evidence by Domain
Select any domain to explore the published evidence, study details, and protocol guidance.
Orthopedic & Post-Surgical
Total knee arthroplasty, ACL reconstruction, Achilles repair, lower limb fractures, osteoarthritis, and stress injuries. Evidence from 386+ participants in systematic review.
Neurological Rehabilitation
Stroke, Parkinson's disease, multiple sclerosis, cerebral palsy, diabetic peripheral neuropathy. Fall-safe enclosed environment enables high-volume gait practice.
Athletic Performance
Overspeed training, aerobic fitness maintenance during injury, return-to-sport progression. Used by professional sports programs nationwide.
Aging & Fall Prevention
Sarcopenia, hip fracture, balance impairment in adults 55+. The enclosed fall-safe design uniquely enables the highest-risk older adults to train safely.
Obesity & Cardiometabolic
Weight management, metabolic conditioning, cardiovascular health. Enables therapeutic exercise for those intolerant of full weight-bearing.
Technology Comparison
LBPP microgravity treadmills vs. harness systems vs. aquatic treadmills. BW% precision, gait mechanics, fall safety, post-surgical applicability.
Differential Air Pressure (DAP) technology was developed by Dr. Robert Whalen at NASA Ames Research Center in the late 1980s and early 1990s — originally to simulate Earth's gravity for astronauts exercising in space. He patented the technology in 1992. Dr. Whalen's son, Sean Whalen, co-founded Boost Treadmills in 2017 alongside Tom Allen, adapting the same principle to reduce gravitational load on Earth. Dr. Robert Whalen serves as an advisor to Boost Treadmills.
Explore by Condition
Select a condition below to view the published evidence, key findings, and recommended protocol parameters.
Evidence Summary — All 12 Conditions
At-a-glance overview. Click any condition button above for full detail, or click a row below.
| Condition | Evidence Type | Studies | Target BW% | Unloading | Key Outcome |
|---|
Click any row to view full condition detail. Click column headers to sort.
Orthopedic & Post-Surgical Rehabilitation
Evidence across fractures, arthroplasty, ligament reconstruction, tendon surgery, and osteoarthritis. A 2024 systematic review (11 studies, 386 participants) confirmed safety, feasibility, and clinically relevant improvements across musculoskeletal disorders.
Running imposes knee contact forces of 3–5× body weight per step. A landmark in vivo study using electronic tibial prostheses directly measured significant, quantifiable GRF reductions during LBPP treadmill use — providing direct biomechanical validation for orthopedic applications.
Neurological Rehabilitation
Stroke, Parkinson's disease, multiple sclerosis, cerebral palsy, diabetic peripheral neuropathy, spinal cord injury, and burn rehabilitation. A 2024 PRISMA systematic review identified 16 studies across neurological populations with promising results in gait and balance outcomes.
Mid-to-late stage Parkinson's disease, stroke, and high-disability MS patients often cannot safely use conventional treadmills due to fall risk and cognitive load. The LBPP enclosed chamber eliminates fall risk during training, enabling high-volume gait repetition central to neuroplasticity-based rehabilitation — which is not achievable with conventional equipment.
Aerobic exercise is one of the most potent stimuli for BDNF — a protein supporting neuronal survival, neuroplasticity, and cognitive function. Treadmill exercise specifically increases hippocampal BDNF in both animal and human studies. In Parkinson's disease, treadmill exercise has been shown to increase BDNF and GDNF in the striatum, potentially providing neuroprotective effects beyond motor benefit. For patients with PD, stroke, or OA who cannot perform standard aerobic exercise, LBPP microgravity treadmills provide access to these neuroplastic benefits that would otherwise be unachievable.
Athletic Performance
Elite and recreational athletes, return-to-sport protocols, overspeed training, and aerobic fitness maintenance during injury.
LBPP microgravity treadmills enable athletes to run at higher absolute speeds than possible overground. With Ground Reaction Forces substantially reduced, athletes can practice sprint mechanics at supramaximal velocities with lower injury risk than overground overspeed methods. This application is used by professional sports programs across multiple disciplines.
Aging, Sarcopenia & Fall Prevention
Evidence for older adult populations across fall risk reduction, sarcopenia management, hip fracture recovery, and balance training.
Falls are the second leading cause of unintentional injury-related deaths globally. One-third of adults over 65 fall each year; 1 in 10 results in a bone fracture. Lower-extremity muscle weakness confers a 5× increase in fall risk. LBPP microgravity treadmills provide a unique dual advantage: enabling progressive load-bearing ambulation for those too deconditioned for standard exercise, while the enclosed design eliminates fall risk during training sessions themselves.
Obesity & Cardiometabolic Health
Evidence for weight management, metabolic conditioning, and cardiometabolic disease risk reduction.
Obesity increases knee joint forces by approximately 4× body weight per walking step. Pain from this loading leads to inactivity, which drives further weight gain and deconditioning. LBPP microgravity treadmills break this cycle — enabling therapeutic exercise at meaningful intensities while protecting joints from the loading that causes pain and injury.
Technology Comparison
LBPP Microgravity Treadmills vs. Harness-Based Body Weight Support vs. Aquatic Treadmills.
Body Weight Percentage (BW%) is the percentage of full body weight the user feels during exercise. Unloading % = 100% minus BW%. Example: a user at 80% BW feels 80% of their body weight and is 20% unloaded. Boost Treadmills allow unloading of up to 80%, meaning a user can feel as little as 20% of their body weight. Aquatic underwater treadmills typically achieve a BW% range of approximately 10–50% BW (50–90% unloading) — with deeper immersion producing greater unloading. Harness systems typically achieve a maximum of approximately 40% unloading (user feels at least ~60% BW).
| LBPP Microgravity Treadmill | Harness / Overhead BWS | Aquatic Treadmill |
|---|
Direct comparative research (Ruckstuhl et al., Gait Posture 2009) found that gait parameters (cadence, stride length, duty factor) were not significantly different between LBPP and harness systems at equivalent body weight levels. However, heart rate was significantly lower and comfort significantly higher during LBPP use — making LBPP preferable for cardiovascular-risk patients and those requiring high levels of unloading.
Harness Body Weight Support: Evidence for Bone & Injury Healing
Harness-based Body Weight Supported Treadmill Training (BWSTT) evidence directly translates to LBPP — confirmed by biomechanical equivalence data.
Ruckstuhl et al. (2009) confirmed gait parameters are NOT significantly different between LBPP and harness systems at equivalent BW%. This means positive outcomes from harness BWSTT studies translate directly to LBPP microgravity treadmills — with the additional advantages of fall safety, 1% BW% precision, and superior user comfort.
Clinical Protocol Guidance
Evidence-based body weight percentage (BW%) and unloading targets by clinical goal. Individual clinical judgement and patient symptom response should always guide specific protocols. These ranges are synthesised from the published literature.
| Clinical Goal | Target BW% | Unloading Level | Key Considerations |
|---|---|---|---|
| Maintain aerobic fitness during injury | 75–90% BW | 10–25% unloading | Use speed to modulate intensity; monitor HR and RPE; direct metabolic measurement required for elite athletes (standard prediction equations unreliable at elite speeds) |
| Post-surgical early ambulation | 40–70% BW | 30–60% unloading | Pain-free movement is the primary goal; progress BW% weekly; ensure strong internal fixation for fracture patients before commencing |
| Stress fracture / bone stress injury | 50–80% BW, progress to 95%+ | 5–50% unloading | Transition to overground running when pain-free at >95% BW sustained for >30 continuous minutes (Vincent et al., 2022) |
| Neurological gait retraining (stroke, SCI) | >70% BW | <30% unloading | Less than 30% unloading produces the most natural gait pattern; vary speed and slope for progressive challenge |
| Parkinson's Disease / Freezing of Gait | 40–60% BW | 40–60% unloading | 2–4 sessions/week; enclosed fall-safe environment is essential; VR combination being studied as emerging option |
| Diabetic Peripheral Neuropathy | ~75% BW | ~25% unloading | 3 sessions/week, 30 min; combine with balance training; monitor for foot ulceration risk |
| Obesity / cardiometabolic health | 75–85% BW | 15–25% unloading | Use ≥75% BW to maintain meaningful caloric expenditure for fat oxidation; HR-based exercise prescription remains valid across all BW% levels; monitor blood pressure |
| Older adult balance & fall prevention | 80–95% BW | 5–20% unloading | Monitor HR and blood pressure; enclosed environment provides safety for high-risk participants; combine with balance challenges as confidence improves |
| Elite athletic performance | 60–80% BW | 20–40% unloading | Direct VO2 or HR measurement required; standard prediction equations are unreliable at elite running speeds (McNeill et al., 2015) |
All parameters shown are synthesised from published peer-reviewed research and are provided for informational reference only. Boost Treadmills is not a medical practice and does not provide clinical advice. Protocol parameters should always be reviewed and approved by a licensed clinician, physical therapist, or treating physician before application to individual patients. The linked studies below are the direct sources for the ranges shown above — clinicians are encouraged to review these publications before applying protocols.
Source Publications by Protocol
Glossary of Terms & Acronyms
All abbreviations and key terms used in this clinical research overview. Search below to find any term.
Quick Reference — BW% by Clinical Goal
A condensed protocol reference card for clinicians. Body Weight % (BW%) is the effective body weight the user feels. Unloading % = 100% minus BW%. All parameters are evidence-based starting points — adjust based on individual patient response and symptom progression. Suitable for posting at the machine.
Post-Surgical Early Ambulation
Pain-free movement is the primary goal. Verify strong internal fixation before commencing for fracture patients.
Stress Fracture / Bone Stress Injury
Do not transition to overground running until criterion is met. Monitor cadence — higher cadence may increase loading rates.
Maintain Aerobic Fitness (Injury)
Training at 75% BW does not significantly reduce VO2peak vs. full weight. Use direct HR/RPE measurement for elite athletes — prediction equations unreliable.
Neurological Gait Retraining
Less than 30% unloading produces the most natural gait pattern. Vary speed and slope progressively. Enclosed design essential for fall-risk patients.
Parkinson's Disease / Freezing of Gait
84% of FOG patients showed improvement at 50% BW, 2×/week, 4 weeks (Baizabal-Carvallo et al. 2020). Enclosed fall-safe environment is essential.
Diabetic Peripheral Neuropathy
Significantly improved gait and balance vs. physiotherapy alone (RCT, N=45). Monitor for foot ulceration risk.
Obesity / Cardiometabolic Health
75% BW still meets ACSM moderate-intensity guidelines. HR-based prescription remains valid at all BW% levels. Monitor blood pressure.
Older Adult / Fall Prevention
Enclosed design eliminates fall risk during training — critical for high-risk patients. Monitor HR and BP throughout.
Elite Athletic Performance
Standard prediction equations are unreliable at elite speeds on LBPP. At 80% BW, VO2 decreases ~34% — greater than proportional to the load reduction (McNeill et al. 2015).
Technology & Evidence Timeline
The development of differential air pressure (DAP) technology from its NASA origins through commercialization and the growth of the clinical evidence base.
Research Gaps & Future Directions
The following gaps have been identified through systematic review of the published literature. Transparency about what remains unknown is a marker of scientific credibility — and these gaps represent the frontier of LBPP research.
The existing evidence base for LBPP technology is substantial and growing rapidly. However, identifying where evidence is thin or absent allows clinicians to apply appropriate caution, guides future research investment, and distinguishes what is well-established from what is extrapolated from related populations. All clinical applications in this document are supported by published evidence; the gaps below represent areas where that evidence could be strengthened.
BDNF & Neuroplasticity — Direct Measurement
No published study has directly measured Brain-Derived Neurotrophic Factor (BDNF) response to LBPP treadmill exercise. Given the strong mechanistic link between aerobic exercise, BDNF, and neurological outcomes in PD, stroke, and cognitive aging, this is a high-priority gap. Animal and standard treadmill data strongly predict a significant LBPP effect.
Multiple Sclerosis — RCTs Absent
Evidence in MS consists of a single case study (N=1, EDSS 6.5) showing a 48% increase in muscle oxidative capacity. No randomised controlled trials have been conducted in MS populations. Given the disability levels and exercise intolerance common in MS, this is a significant gap with high clinical relevance.
Long-Term Body Composition & Bone Density
Most published studies are short-term (2–12 weeks). Longitudinal data on sustained muscle hypertrophy, bone density preservation, and fat mass changes with continued LBPP training are lacking. Long-term outcomes are critical for chronic condition management and aging populations.
Parkinson's Disease — Cognitive Outcomes
Current PD research focuses almost exclusively on motor outcomes (gait, balance, FOG). The potential for LBPP-enabled aerobic exercise to influence cognitive decline, BDNF levels, and dopaminergic function — all of which respond to aerobic exercise in PD — has not been directly studied, despite being one of the most important quality-of-life domains.
Optimal Protocol Parameters
Ideal combinations of BW%, speed, incline, session duration, frequency, and BW% progression rate have not been definitively established for most clinical populations. Most published protocols are derived from single studies or clinical consensus rather than comparative dose-response research.
Comparative Effectiveness at Scale
Head-to-head RCTs comparing LBPP to harness and aquatic modalities across specific diagnoses remain limited. Most direct comparisons are in stroke (Duran et al. 2023). Data in PD, OA, and fracture populations are sparse, constraining definitive modality selection guidance.
Diabetic Neuropathy — Long-Term Outcomes
The 12-week RCT (N=45) showed meaningful gait and balance improvements. Long-term effects on HbA1c, foot ulceration incidence, neuropathy progression, and fall rates over 6–12 months have not been studied. These outcomes are central to the clinical rationale for DPN exercise intervention.
VR + LBPP Combination Therapy
A feasibility pilot in PD (N=12) demonstrated 97% adherence and significant improvements with VR+LBPP. This combination — addressing both motor and cognitive deficits simultaneously — has not been studied in RCTs in PD, stroke, or other neurological conditions where dual-tasking during gait training is clinically relevant.
Cardiometabolic Disease — Specific RCTs
Rationale and pilot metabolic data support LBPP use in cardiovascular disease risk groups. However, disease-specific RCTs in heart failure, hypertension, and type 2 diabetes (beyond DPN) are absent from the literature. The German Center for Cardiovascular Research explicitly called for such studies.
Pediatric Populations Beyond Cerebral Palsy
LBPP evidence in children and adolescents is almost entirely in cerebral palsy. Conditions such as traumatic brain injury, developmental coordination disorder, and juvenile idiopathic arthritis have not been studied, despite the theoretical rationale for LBPP being equally applicable.
Cognitive Aging & Dementia Prevention
The relationship between LBPP-enabled aerobic exercise and cognitive health markers — including hippocampal neurogenesis, memory function, and dementia prevention — in older adults has not been directly studied. Given the BDNF mechanism, this may represent a significant unrealised benefit of the technology in aging populations.
Military & Occupational Rehabilitation
Several government and military locations were among Boost Treadmills' first customers. Military applications (combat-related musculoskeletal injuries, return-to-duty fitness during recovery) have not been studied in published literature, despite strong clinical rationale and documented real-world use.
Getting Started with Boost Treadmills
Whether you are a clinician, sports medicine professional, hospital administrator, or athletic trainer, here is how to integrate microgravity treadmill technology into your program.
Johns Hopkins Rehabilitation Network, Northwestern University Athletics, and several government locations were among the first to receive a Boost Treadmill.
Identify Your Use Case
Review the evidence by condition and identify which patient populations would benefit most. Common starting points: post-surgical rehabilitation, gait training for neurological conditions, return-to-sport protocols, and fall prevention in older adults.
Review the Clinical Evidence
Use this explorer to review published evidence for your setting. Every protocol recommendation links to its source publication. Share the PDF with your clinical team or procurement committee.
Talk to the Boost Team
Boost Treadmills is a team of performance trainers and coaches — and the original team behind AlterG before founding Boost in 2017. We work directly with every customer to find the right solution for your setting.
Choose Your Model
Two current models: the Boost 2 (2022) for elite sports and performance environments, and the Boost 3 (November 2025) for medical clinics, training facilities, and home use — bringing Boost 2 technology to a wider audience at a dramatically more accessible price. Both provide up to 80% unloading in 1% increments.
Onboarding & Training
The Boost team provides onboarding support for all customers. The device is intuitive and straightforward to integrate into existing rehabilitation or training programs.
The Boost Product Lineup
The original Boost Treadmill. Built on the Woodway 4Front platform. Established Boost in sports medicine and clinical rehabilitation. Now discontinued.
Designed for elite sports and high-performance environments. Significant engineering advances over Boost 1. The benchmark for professional athletic settings, team training rooms, and sports medicine.
Brings Boost 2 technology to medical clinics, training facilities, and home users. Clinical-grade precision and up to 80% unloading at a dramatically more accessible price point.
Ready to Learn More?
Get in touch with the Boost team to find the right solution for your setting.
Contact the Boost Team →AlterG® and Anti-Gravity Treadmill® are trademarks of AlterG Inc., not affiliated with Boost Treadmills. Not medical advice.
