Abstract Title

The Effects of an External Lifting Device on Lifting Mechanics

Additional Funding Sources

The project described was supported by a student grant from the UI Office of Undergraduate Research.

Abstract

Context: The occurrence of knee valgus, anterior pelvic tilt, and subsequent quadricep dominance while lifting can lead to injury and hindered performance. Historically, a lumbar assistive device can be used to correct lifting form and increase performance. However, the additional correction of knee valgus and resulting quadricep dominance could also aid in injury prevention and performance improvement.

Objective: To investigate the effects of an external corrective lifting device on muscle activation patterns and movement mechanics. It is hypothesized that while wearing the corrective device, movement mechanics will shift causing muscle activation patterns to change.

Methodology: 12 apparently healthy participants completed both sessions, 9 with a history of resistance training (at least 1 year of free-weight training) and 3 without a history of resistance training in the last year. Data collection consisted of two sessions: 1) consenting, screening, familiarization of the corrective device and establishment of 5 repetition maximum (5RM) for lifting tasks (BS: Back Squat; DL: Dead lift). 2) performance of 3 trials of each tasks at multiple intensities (Body weight, 50% 5RM, and 100% 5RM). Device condition order was counterbalanced with odd participants performing each task without the device first and even participants performed with the device first. During session two, twelve Delsys surface electromyography (sEMG) sensors were attached to six muscles bilaterally: Rectus Femoris, Bicep Femoris, Adductor Longus, Gluteus Maximus, Gluteus Medius, and Erector Spinae groupings. Movement mechanics were assessed using an 8-camera Vicon motion capture system synced with two AMTI force platforms. Participants were additionally instrumented with a full-body passive reflective marker set to represent skeletal motion. To ensure accuracy between models, reflective markers representing the pelvis (L/R ASIS, L/R ILCT, L/R PSIS) were measured from the marked points on the ground to ensure similar placement between conditions. For the BS and DL conditions, foot positions were outlined on the force platforms to reduce influence of foot position on differences between conditions. Participants self-selected their grips and shoe ware and asked to maintain that choice through subsequent trials. Following the completion of all tasks in both device conditions, participants completed a questionnaire about their thoughts on the device.

Data: Current data available includes participant responses from the post session 2 survey assessment. From the survey's responses there was a notable trend of device satisfaction based on questions regarding comfort, donning and doffing, perceived fit, and perceived aid during performance. Overall from the free-response questions provided in the survey participants had mixed reviews on if Sure Squat helped them during the tasks. The muscle activation and the movement mechanic data are currently being processed. To assess the differences between device conditions, dependent t-tests will be conducted on all movement mechanic dependent variables. Muscle activation patterns will be assessed in terms of muscle activation onset and root mean squared values within phases of the tasks.

Conclusion: It appears from the initial data that those who were in the non-resistance training identified a benefit using the device. It is unclear whether there is a benefit in lifting mechanics due to the data still being processed. From participant self-perceived device-aid during a task non-resistance trained individuals reported an increased awareness of form while wearing the device.

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The Effects of an External Lifting Device on Lifting Mechanics

Context: The occurrence of knee valgus, anterior pelvic tilt, and subsequent quadricep dominance while lifting can lead to injury and hindered performance. Historically, a lumbar assistive device can be used to correct lifting form and increase performance. However, the additional correction of knee valgus and resulting quadricep dominance could also aid in injury prevention and performance improvement.

Objective: To investigate the effects of an external corrective lifting device on muscle activation patterns and movement mechanics. It is hypothesized that while wearing the corrective device, movement mechanics will shift causing muscle activation patterns to change.

Methodology: 12 apparently healthy participants completed both sessions, 9 with a history of resistance training (at least 1 year of free-weight training) and 3 without a history of resistance training in the last year. Data collection consisted of two sessions: 1) consenting, screening, familiarization of the corrective device and establishment of 5 repetition maximum (5RM) for lifting tasks (BS: Back Squat; DL: Dead lift). 2) performance of 3 trials of each tasks at multiple intensities (Body weight, 50% 5RM, and 100% 5RM). Device condition order was counterbalanced with odd participants performing each task without the device first and even participants performed with the device first. During session two, twelve Delsys surface electromyography (sEMG) sensors were attached to six muscles bilaterally: Rectus Femoris, Bicep Femoris, Adductor Longus, Gluteus Maximus, Gluteus Medius, and Erector Spinae groupings. Movement mechanics were assessed using an 8-camera Vicon motion capture system synced with two AMTI force platforms. Participants were additionally instrumented with a full-body passive reflective marker set to represent skeletal motion. To ensure accuracy between models, reflective markers representing the pelvis (L/R ASIS, L/R ILCT, L/R PSIS) were measured from the marked points on the ground to ensure similar placement between conditions. For the BS and DL conditions, foot positions were outlined on the force platforms to reduce influence of foot position on differences between conditions. Participants self-selected their grips and shoe ware and asked to maintain that choice through subsequent trials. Following the completion of all tasks in both device conditions, participants completed a questionnaire about their thoughts on the device.

Data: Current data available includes participant responses from the post session 2 survey assessment. From the survey's responses there was a notable trend of device satisfaction based on questions regarding comfort, donning and doffing, perceived fit, and perceived aid during performance. Overall from the free-response questions provided in the survey participants had mixed reviews on if Sure Squat helped them during the tasks. The muscle activation and the movement mechanic data are currently being processed. To assess the differences between device conditions, dependent t-tests will be conducted on all movement mechanic dependent variables. Muscle activation patterns will be assessed in terms of muscle activation onset and root mean squared values within phases of the tasks.

Conclusion: It appears from the initial data that those who were in the non-resistance training identified a benefit using the device. It is unclear whether there is a benefit in lifting mechanics due to the data still being processed. From participant self-perceived device-aid during a task non-resistance trained individuals reported an increased awareness of form while wearing the device.