by Kathleen O'Neill, DPT
The AlterG (or G-Trainer) is an anti-gravity treadmill that uses a pressurized air chamber to reduce load and offload body weight percentage in precise increments. Using positive air pressure, the AlterG essentially unweights patients to decrease gravitational forces on the body. It’s an incredible tool in the rehab world, allowing us to offload patients who are acutely injured and progressively return to full-load walking and running post injury or surgery.
In addition to serving as a valuable rehab tool, the AlterG can also be an effective recovery and injury prevention method for endurance runners. Studies have shown that running on an anti-gravity treadmill decreases ground reaction forces, meaning less load is being transmitted from the ground up into muscles, tendons, bones and joints with each foot strike. Runners who replace an easy, midweek recovery run with an AlterG run can maintain their high weekly mileage while placing significantly less stress on their musculoskeletal system.
Current research has also found that runners can still maintain load with higher intensity running on the AlterG, indicating its value in helping the injured runner maintain fitness. A 2015 study by Kline, et al looked at the metabolic cost of running at 50-100% body weight on an AlterG treadmill, and found that similar loads can be maintained by increasing running speed as percentage of body weight is offloaded.
They provided a conversion table based on % body weight and pace in miles per hour. For example: if a runner at 70% body weight is looking to exert the same amount of energy that they would running 7.5 MPH (8:00 mile pace) at full body weight, they would need to increase the AlterG treadmill speed to 10.6 MPH (5:40 mile pace). Additional studies have found that increasing incline on the AlterG treadmill can help maintain intensity at decreased body weight %. Although this chart is a helpful guide, other metrics, including heart rate and perceived exertion, will help appropriately manage the intensity of your AlterG run.
Athletes and coaches: consider the AlterG as a tool if any injuries should arise during a training block. For runners looking to maintain fitness while injured, your physical therapist can guide you through an individualized plan of care with AlterG runs built in to keep you running as you rehab. Reach out for more details!