Reviewed by Tyler Tice, PT, DPT, OCS, ATC
Introduction
Rehabilitation after running-related injuries often involves non-weight-bearing activities to reduce joint stress while preserving fitness. Traditional methods like elliptical and pool training provide limited replication of running biomechanics. Antigravity treadmill training introduces partial body weight support (BWS) using air pressure technology, enabling early mobilization and reduced mechanical load on injured tissues. This article reviews the physiological and biomechanical benefits of antigravity training, providing evidence-based protocols and case studies to guide rehabilitation professionals.
Support Mechanism of the Antigravity Treadmill
Antigravity treadmills utilize positive air pressure within an enclosed chamber to reduce the runner’s effective body weight by up to 80%. The system stabilizes the lower body, offering precise control over unweighting levels while maintaining natural running kinematics. Adjustable support ensures suitability for varying heights and conditions, allowing individuals to engage in controlled, impact-reduced exercise during recovery.
Antigravity Treadmill Training for Rehabilitation
Antigravity treadmills enable early weight-bearing activities without exacerbating injuries. By decreasing mechanical stress, they minimize muscle atrophy, improve joint mobility, and maintain neuromuscular patterns. Athletes can preserve cardiorespiratory fitness by adjusting treadmill speed or incline to match metabolic demands. Studies show that antigravity treadmills allow runners to achieve submaximal and maximal training intensities comparable to overground running, even at 85–90% body weight.
Expected Biomechanical Changes
- Temporal-Spatial Parameters: Unweighting alters cadence, stride length, and ground contact time. As BWS increases, cadence decreases, and stride length grows, necessitating careful monitoring to avoid maladaptive patterns during the transition back to full weight-bearing running.
- Kinematics and Kinetics: Reduced BWS impacts joint motion, including decreased dorsiflexion and peak knee flexion, while lowering ground reaction forces and vertical stiffness. Proper adjustment and gradual progression are critical to avoid compensatory movement patterns.
- Muscle Activity: Muscle activation in lower extremity muscles generally decreases with higher BWS. However, increasing cadence during training can maintain neuromuscular activation patterns, preserving functional strength.
Interventions and Case Studies
- Evidence supports the use of antigravity treadmills for diverse injuries, such as tibial stress fractures, Achilles tendon repairs, and knee osteochondral defects.
- Case 1 (Osteochondral Repair): A runner with knee cartilage damage successfully transitioned to ground running after a structured eight-week program with progressive BWS adjustments. The patient achieved pain-free running with improved self-efficacy.
- Case 2 (Medial Tibial Stress Fracture): An elite runner utilized a phased return-to-run protocol with incremental increases in BWS and running duration. This approach facilitated recovery without re-injury, demonstrating the treadmill’s utility for managing bone stress injuries.
Technical Considerations and Transition Strategies
Accurate setup is crucial, as improper positioning of the treadmill frame can alter BWS levels. Gradual increases in treadmill speed or incline during rehabilitation help maintain aerobic fitness and muscle engagement. Transitioning from BWS to overground running requires monitoring for pain and ensuring safe loading thresholds.
Contributions to Physical Therapy
Antigravity treadmill training offers physical therapists a powerful tool for managing running-related injuries. Its ability to reduce impact forces while preserving fitness accelerates recovery and supports early mobilization. By enabling progressive loading and facilitating a safe return to sport, antigravity treadmills can improve functional outcomes and reduce the risk of re-injury. Therapists can tailor protocols based on injury type, ensuring individualized care that aligns with each patient’s recovery goals.
- Vincent HK, Madsen A, Vincent KR. Role of Antigravity Training in Rehabilitation and Return to Sport After Running Injuries. ASMAR. 2022;4(1):e141-e149. doi:10.1016/j.asmr.2021.09.031