Accuracy of unloading with the anti-gravity treadmill

Area of Science:

• Biomechanics
• Sports Medicine
• Rehabilitation Engineering

Background:

• Body weight (BW)-supported treadmill training is widely used in sports and rehabilitation.
• The accuracy of positive pressure treadmills, like the AlterG Anti-Gravity Treadmill, is not well-established.

Purpose of the Study:

• To evaluate the accuracy of the body weight (BW) support settings on the AlterG Anti-Gravity Treadmill.
• To assess discrepancies between predicted and measured BW support across an unloading spectrum (100% to 20% BW).

Main Methods:

• Thirty-one healthy adults (15 men, 16 women) participated.
• Participants were weighed inside the AlterG treadmill at 10% BW increments from 100% to 20%.
• Predicted BW from the AlterG was compared against measured BW.

Main Results:

• Significant differences between predicted and measured BW were observed at most unloading levels.
• The largest discrepancies (>5%) occurred at 100% BW (measured lower than predicted) and at 30% and 20% BW (measured higher than predicted).
• Accuracy was acceptable between 70% and 90% BW.

Conclusions:

• The AlterG Anti-Gravity Treadmill exhibits notable inaccuracies in reporting body weight support, particularly at maximal unloading (100% BW) and high levels of unloading (20-30% BW).
• These findings are crucial for accurate application in athletic training, physical therapy, and research settings.
• Consideration of these discrepancies is essential when interpreting results or prescribing exercise using this technology.