Lever-drive wheelchairs lower physical strain but are less maneuverable than push-rim wheelchairs. Here, we study a possible solution in which the user simultaneously actuates clutches mounted between the levers and wheels each stroke via a clutch handle attached to one lever; this solution is of particular interest for user groups with only one functional hand. First, to demonstrate maneuverability, we show how this "yoked clutch" allows an experienced user to maneuver a constrained space. Then, we compared the difficulty of learning a yoked clutch chair to a conventional lever-drive transmission (i.e. a one-way bearing). Twenty-two unimpaired novice adults navigated a figure-eight track during six training sessions over two weeks. Participant mean speed improved roughly 60% for both chairs, with similar exponential improvement time constants (3 days) and final speeds. However, speed improvement mostly took place overnight rather than within the session for hand-clutching, and the physiological cost index was also about 40% higher. These results indicate that while hand-clutching is no more difficult to learn than a lever-drive, it is reliant on overnight improvement. Also, its increased maneuverability comes with decreased efficiency. We discuss how the yoked clutch may be particularly well suited for individuals with stroke during inpatient rehabilitation.

Many people with a stroke have a severely paretic arm, and it is often assumed that they are unable to learn novel, skilled behaviors that incorporate use of that arm. Here, we show that a group of people with chronic stroke (n = 5, upper extremity Fugl-Meyer scores: 31, 30, 26, 22, 8) learned to use their impaired arm to propel a novel, yoked-clutch lever drive wheelchair. Over six daily training sessions, each involving about 134 training movements with their “useless” arm, the users gradually achieved a 3-fold increase in wheelchair speed on average, with a 4–6 fold increase for three of the participants. They did this by learning a bimanual skill: pushing the levers with both arms while activating the yoked-clutches at the right time with their ipsilesional (i.e. “good”) hand to propel the wheelchair forward. They perceived the task as highly motivating and useful. The speed improvements exceeded a 1.5-factor improvement observed when young, unimpaired users learned to propel the chair. The learning rate also exceeded a sample of learning rates from a variety of classic learning studies. These results suggest that appropriately-designed assistive technologies (or “unmasking technologies - UTs”) can unleash a powerful, latent ability for motor learning even for severely paretic arms. While UTs may not reduce clinical impairment, they may facilitate large improvements in a specific functional ability.

0.893, and both methods together reported an ICC of 0.970. The Photoshop-assisted percent fatty infiltration method resulted in an ICC of 0.915. for free-hand CSA vs. Photoshopassisted CSA measurements ICCs of 0.945 and 0.873 were found, respectively. Kappa for Goutallier scores were as follows: 0.291 between researchers 1-2, 0.291 between researchers 1-3, and 0.455 between researchers 2-3. Kappa for Quartile scores were 0.534 between researchers 1-2, 0.658 between researcher 1-3, and 0.416 between researchers 2-3. Both Goutallier and Quartile scores showed significantly high correlations with the photoshop-assisted percent fatty infiltration in multifidus (r¼0.886;0.870) and erector spinae (r¼0.828;0.817) muscles at all intervertebral disc levels. Conclusions: We found inter-rater reliability is significantly high in all paraspinal muscle measurements. fCSA with free hand technique had the highest inter-rater reliability and required less time than photoshop-assisted measurements. We had the best inter-rater reliability when we assessed the fatty infiltration in muscle with both Goutallier and Quartile classifications. We recommend fCSA measurement with free hand technique for atrophy, and Goutallier and Quartile classifications together for fatty infiltration assessment.

Nearly half of individuals with stroke experience some form of long-term disability and stroke is one of the main causes of wheelchair use in the United States [1]. Early rehabilitation in the acute phase of stroke has been shown critical to promoting motor plasticity and patient outcomes. However, research shows that only 32% of the time during inpatient rehabilitation is spent in active therapy, while the rest of the time is spent on other activities around the ward [2]. For walking impairment, it is especially important for patients to experience similar force loading and practice the patterning of gait in order to recover [3]. However, in a typical therapy session focused on gait rehabilitation patients only will take about 300 steps on average. This is far below what has been thought needed for humans to learn how to walk [4].