TY - JOUR
T1 - AlterG Anti-Gravity Treadmill Accuracy of Unloading Is Affected by Support Frame Height
AU - De Heer, Hendrik D.
AU - Kaufman, Alex
AU - Repka, Chris P.
AU - Rojas, Katia
AU - Charley, Brenda
AU - Bounds, Roger
N1 - Publisher Copyright:
© 2021 NSCA National Strength and Conditioning Association. All rights reserved.
PY - 2021/10/1
Y1 - 2021/10/1
N2 - The AlterG Anti-Gravity Treadmill uses air pressure to provide partial body-weight support (BWS), lowering impact forces and metabolic demand of walking and running. Users wear specialized shorts that zip onto a bag supported by a metal bar frame covering the treadmill. The frame is placed at hip height in positions numbered 1-9, adjusted up or down based on preference. Machine accuracy in providing BWS is important to achieve desired training effects, but it is unknown whether frame placement impacts accuracy. Twenty subjects (10 men/women) were weighed in 10% increments from 0 to 60% BWS with the frame at hip height (iliac crest), the "neutral" position, and reweighed with the frame placed up to 3 numbers above or below hip height. Although the machine displayed the same proportion BWS, placing the frame higher than the neutral position resulted in significantly more support, whereas placing the frame lower led to less support. At 10% BWS, placing the frame 3 positions higher resulted in 3% more support compared with the neutral position (13.1% BWS, p < 0.001) and 3 positions lower in 4.7% less support (5.3% BWS, p < 0.001). Deviances were greater with more BWS. At 60% BWS, 3 positions higher than neutral resulted in 71.2% BWS (11.2% more than expected, p < 0.001) and 3 below 48.1% BWS (12.9% below expected, p < 0.001), total 24.1% difference. These findings suggest that the position of the support frame significantly impacts the AlterG accuracy in providing BWS, with placement higher than hip height resulting in more support than displayed by the machine and lower placement resulting in less support.
AB - The AlterG Anti-Gravity Treadmill uses air pressure to provide partial body-weight support (BWS), lowering impact forces and metabolic demand of walking and running. Users wear specialized shorts that zip onto a bag supported by a metal bar frame covering the treadmill. The frame is placed at hip height in positions numbered 1-9, adjusted up or down based on preference. Machine accuracy in providing BWS is important to achieve desired training effects, but it is unknown whether frame placement impacts accuracy. Twenty subjects (10 men/women) were weighed in 10% increments from 0 to 60% BWS with the frame at hip height (iliac crest), the "neutral" position, and reweighed with the frame placed up to 3 numbers above or below hip height. Although the machine displayed the same proportion BWS, placing the frame higher than the neutral position resulted in significantly more support, whereas placing the frame lower led to less support. At 10% BWS, placing the frame 3 positions higher resulted in 3% more support compared with the neutral position (13.1% BWS, p < 0.001) and 3 positions lower in 4.7% less support (5.3% BWS, p < 0.001). Deviances were greater with more BWS. At 60% BWS, 3 positions higher than neutral resulted in 71.2% BWS (11.2% more than expected, p < 0.001) and 3 below 48.1% BWS (12.9% below expected, p < 0.001), total 24.1% difference. These findings suggest that the position of the support frame significantly impacts the AlterG accuracy in providing BWS, with placement higher than hip height resulting in more support than displayed by the machine and lower placement resulting in less support.
KW - bar height
KW - body-weight support
KW - lower-body positive pressure
KW - precision
KW - running
KW - support structure
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U2 - 10.1519/JSC.0000000000003223
DO - 10.1519/JSC.0000000000003223
M3 - Article
AN - SCOPUS:85123729345
SN - 1064-8011
VL - 35
SP - 2910
EP - 2914
JO - Journal of Strength and Conditioning Research
JF - Journal of Strength and Conditioning Research
IS - 10
ER -