Triceps Activation Amplitudes during Functional Activities

Objective: To investigate the muscular activation amplitudes of three regions of triceps musculature during functional activities. We hypothesized that the medial and lateral triceps would be greatest in the terminal 30° arc of extension activities. Design: Cross sectional. Setting: Musculoskeletal Clinical Laboratory. Participants: 20 healthy subjects recruited from a sample of convenience. Intervention: Fine wire electromyograhical (EMG) electrodes were placed into the medial, central, and lateral triceps to measure muscular activation amplitude and two dimensional electrogoniometric kinematic activity was recorded during functional activities associated with activities of daily living. Main Outcome Measure(s): Root mean squared amplitudes of triceps muscles normalized to maximal voluntary isometric contractions that are sub-divided into 30° arcs of motion. Results: The medial triceps generated significantly more EMG activity during the terminal 30° arc of supine extension (54±11%MVIC, p\u3c.05) and during the pushing activity (29±7% MVIC, p\u3c.01). The lateral triceps remained relatively constant throughout all arcs, while the central triceps consistently generated the lowest EMG activation level across all functional tasks. Conclusion: The hypothesis is partially supported as the medial triceps generated more activity in two of the three tasks during the terminal 30° of extension. The lateral portion is activated consistently throughout the extension motion and acts as a dynamic stabilizer during extension activities. These results indicate that the constant activity of the lateral insertion of the triceps, in conjunction with the terminal extension activity of the medial insertion, play a primary role in terminal elbow extension, especially in anti-gravity and load bearing activities. This new data has implications for surgical approaches to the elbow, management of elbow injuries, and rehabilitation of this joint

High Asymptomatic Carriage With the Omicron Variant in South Africa

We report a 23% asymptomatic severe acute respiratory syndrome coronavirus 2 (SARS CoV-2) Omicron carriage rate in participants being enrolled into a clinical trial in South Africa, 15-fold higher than in trials before Omicron. We also found lower CD4 + T-cell counts in persons with human immunodeficiency virus (HIV) strongly correlated with increased odds of being SARS-CoV-2 polymerase chain reaction (PCR) positive