The quadruple approach in the title refers to four different studies over a period of 3 years. The common factor in these studies is the methodology of the (Brussels) Electromyographic Signal Processing and Analysis System (ESPAS), a hardware and software EMG data acquisition system that has constantly been improved. Therefore, the ESPAS methodology is described extensively (i.e. the electrodes, amplifier, tape-recorder and processing hardware). Experiment 1 investigated muscular behaviour in target shooting, both indoors (18 and 25 m) and outdoors (50, 70 and 90 m). It was found (via iEMG) that a significant increase in activity only exists between 25 and 50 m, and that there is no linear increase of activity with increased distance. No differences in muscular pattern (IDANCO system: Clarys and Cabri, 1988) or activity between the indoor distances and between the outdoor distances were found. Experiment 2 investigated the muscular economy of four string grips: the three-finger grip, two-finger grip, thumb grip and reversed grip. The largest variations in activity were found for the two most unfamiliar grips, i.e. the thumb and reversed grips; however, low iEMG and the rapid precision improvement (over a limited number of shots) suggest that the thumb grip, if practised long enough, might be the most economical technique. Experiment 3 attempted to differentiate muscular activity and a number of performance variables in three different populations of archers--Olympic athletes, National competitors and beginners--in order to obtain feedback regarding improved performance. Apparently, overall muscle pattern, intensities and arrow speed were not discriminatory. The differences found between the groups (or levels of skill) were affected by the ability to reproduce identical patterns and arrow velocities in consecutive shots and by the constancy of neuromuscular control of the M. trapezius, M. biceps brachii and M. extensor digitorum. Finally, Experiment 4 investigated the muscular activity of elite archers shooting at distances of 70 and 90 m with and without stabilizers. Differences in iEMG were not supported by differences in precision. Over time, the low iEMG in shooting without stabilizers increases precision and delays fatigue.

The use of video games during exercise, exergaming, has been shown to increase energy expenditure without increasing perceived exertion [1]. This suggests that exergaming may be an effective way to engage a patient during rehabilitation and increase adherence to a rehabilitation regime. Existing exergame systems are designed with able bodied users in mind and often combine hand controlled game play while using lower limbs for aerobic exertion, making current systems inaccessible to individuals with spinal cord injuries and others without lower limb function. Our earlier work on increasing exercise accessibility includes developing an ergometer for supine use for patients who have recently had a flap procedure [2]. The goal of the present project was to create an engaging, interactive video game designed for use during arm ergometry by individuals with spinal cord injury (SCI) in either the supine or seated position.

Most commercially available lower-limb prostheses are designed for walking, not for standing. The Minneapolis VA Health Care System has developed a bimodal prosthetic ankle-foot system with distinct modes for walking and standing [1]. With this device, a prosthesis user can select standing or walking mode in order to maximize standing stability or walking functionality, depending on the activity and context. Additionally, the prosthesis was designed to allow for an “automatic mode” to switch between standing and walking modes based on readings from an onboard Inertial Measurement Unit (IMU) without requiring user interaction to manually switch modes. A smartphone app was also developed to facilitate changing between walking, standing and automatic modes. The prosthesis described in [1] was used in a pilot study with 18 Veterans with lower-limb amputations to test static, dynamic, and functional postural stability. As part of the study, 17 Veterans were asked for qualitative feedback on the bimodal ankle-foot system (Table 1). The majority of participants (82%) expressed an interest in having an automatic mode. The participants also indicated that the automatic mode would need to reach walking mode on their first step and to lock the ankle quickly once the standing position was achieved. When asked about how they wanted to control the modes of the prosthesis, 82% wanted to use a physical switch and only 12% wanted to use a smartphone app. The results indicated that the following major design changes would be needed: 1) A fast and accurate automatic mode 2) A physical switch for mode changes This paper describes the use of machine learning algorithms to create an improved automatic mode and the use of stakeholder feedback to design a physical switch for the bimodal ankle-foot system.

Men and women with lower limb amputations struggle with managing the balance between prosthesis alignment and shoe heel rise. A novel prosthetic ankle-feet system is being developed to support a wider range of footwear options for men and women with lower limb amputations. Each rigid foot is customized to fit the footwear of choice and can be rapidly attached to (or released from) an ankle unit which remains attached to the prosthesis. The ankle unit has a mass of 318g and is small enough to fit in the design volume of a 22cm foot across a range of heel rises. The ankle uses elastomeric bumpers arranged in a wiper design to maximize space efficiency. Structural testing has shown that the 3D printed custom Nylon 12 feet withstood 4584N of forefoot loading without failure based on the ISO 10328 loading parameters, indicating suitable strength to support safe human use in the laboratory. The feet have a mass of 446g. Feedback from two women Veterans with lower limb amputations reinforced the importance of improving access to shoes with different heel rises. Future activities will include cyclic fatigue testing, additional weight reduction, and incorporating suggested design refinements.

A novel ankle-foot prosthesis with adjustable range-of-motion limits was developed to support implementation of gradual training protocols in the physical therapy of new amputees. Stakeholder interviews drove design requirements that guided the development. Our first prototype did not pass structural strength testing, but with minor revisions to some components, our second prototype was able to pass structural strength testing to the P6 load level (125kg user) of the ISO 10328 standard for prosthetic feet. The system is ready for laboratory testing with prosthesis users and clinicians to generate further insight for future design iterations.