Does fatigue influence joint-specific work and ground force production during the first steps of maximal acceleration?

During initial acceleration, the first steps of a maximal-effort (sprint) run often determine success or failure in the capture and evasion of an opponent, and is therefore a vital factor of success in many modern sports. However, accelerative events are commonly performed after having already run considerable distances, and the associated fatigue should impair muscle force production and thus reduce acceleration. Despite this, the effects of running-induced fatigue on our ability to accelerate as well as the running technique used to achieve it have received little attention. We recorded 3-D kinematics and ground reaction forces during the first three steps of the acceleration phase from a standing start before and after performing a high-speed, multi-directional, fatiguing run-walk protocol in well-trained running athletes who were habituated to accelerative sprinting. We found that the athletes were able to maintain their acceleration despite changing running technique, which was associated with use of a more upright posture, longer ground contact time, increased vertical ground reaction impulse, decreased hip flexion and extension velocities, and a shift in peak joint moments, power, and positive work from the hip to the knee joint; no changes were detected in ankle joint function. Thus, a compensatory increase in knee joint function alleviated the reduction in hip flexor-extensor capacity. These acute adaptations may indicate that the hip extensors (gluteal and hamstring muscle groups) were more susceptible to fatigue than the ankle and knee musculature, and may thus be a primary target for interventions promoting fatigue resistance.

Reassessing the disability divide: unequal access as the world is pushed online.

In a time when a global pandemic has forced people to use technology for almost every aspect of their day-to-day lives, it is important to determine if specific disadvantaged groups are appropriately connected to the digital world. This paper attempts to assess whether people with disabilities (PWD) own computers, connect to the Internet, and participate in online activities at the same rates as the general population. Using comprehensive data from the 2017 Current Population Survey we find that PWD still lag behind in computer ownership and Internet access. This result is driven by those with physical, mental, and emotional impairments along with those with multiple disabilities. We also find that the online activities of PWD are similar to the general population for half of the activities studied, while falling behind in areas such as online communication and finances. Our results also indicate relatively high confidentiality concerns related to online activities among specific disabled groups. We do find PWD are moderately more likely than others to use the Internet for health-related activities in general. Overall, our results indicate the disability divide has been partially bridged, but that given the state of the world more can be done to ensure this already disadvantaged group is not left further behind.

Partially retained small finger flexor digitorum profundus function despite complete tendon loss in the forearm.

A case of traumatic laceration of the small finger flexor digitorum profundus (FDP) tendon in the distal forearm with retained partial active flexion at the small finger distal interphalangeal joint (DIP) joint is described. Tendinous interconnections between the ring and small FDP tendons and lumbrical muscles may permit partial FDP function at the DIP joint despite a complete deficit of the proximal tendon.