Faculty of Applied Health Sciences
http://hdl.handle.net/10464/5750
2024-03-20T01:36:34ZPost-activation potentiation and potentiated motor unit firing patterns in boys and men
http://hdl.handle.net/10464/18244
Post-activation potentiation and potentiated motor unit firing patterns in boys and men
Background: Post-activation potentiation (PAP) describes the enhancement of twitch torque following a conditioning contraction (CC) in skeletal muscle. In adults, PAP may be related to muscle fibre composition and is accompanied by a decrease in motor unit (MU) firing rates (MUFRs). Muscle fibre composition and/or activation is different between children and adults. This study examined PAP and MU firing patterns of the potentiated knee extensors in boys and men. Methods: Twenty-three boys (10.5±1.3 years) and 20 men (23.1±3.3 years) completed familiarization and experimental sessions. Maximal isometric evoked-twitch torque and MU firing patterns during submaximal contractions (20% and 70% maximal voluntary isometric contraction, MVIC) were recorded before and after a CC (5s MVIC). PAP was calculated as the percent-increase in evoked-twitch torque after the CC. MU firing patterns were examined during submaximal contractions before and after the CC using Trigno Galileo surface electrodes (Delsys Inc) and decomposition algorithms (NeuroMap, Delsys Inc). MU action potential amplitudes (MUAPamp) and MUFRs were calculated for each MU and exponential MUFR-MUAPamp relationships were calculated for each participant and trial. Results: PAP was higher in men than in boys (98.3±37.1% vs. 68.8±18.3%, respectively; p=0.002). Following potentiation, the rate of decay of the MUFR-MUAPamps relationship decreased in both contractions, with a greater decrease among boys during the high-intensity contractions. Conclusion: Lower PAP in the boys did not coincide with smaller changes in potentiated MU firing patterns, as boys had greater reductions in MUFRs with potentiation compared with men in high-intensity contractions.
2023-12-30T00:00:00ZChild-Adult differences in antagonist muscle coactivation: A systematic review
http://hdl.handle.net/10464/17381
Child-Adult differences in antagonist muscle coactivation: A systematic review
Woods, Stacey; O'Mahoney, Caragh; McKiel, Andrew; Natale, Laurel; Falk, Bareket
Antagonist coactivation is the simultaneous activation of agonist and antagonist muscles during a motor task. Age-related changes in coactivation may contribute to observed differences in muscle performance between children and adults. Our aim was to systematically summarize age-related differences in antagonist muscle coactivation during multi-joint dynamic and single-joint isometric and isokinetic contractions. Electronic databases were searched for peer-reviewed studies comparing coactivation in upper or lower extremity muscles between healthy children and adolescents/young adults. Of the 1083 studies initially identified, 25 met eligibility criteria. Thirteen studies examined multi-joint dynamic movements, 10 single-joint isometric contractions, and 2 single-joint isokinetic contractions. Of the studies investigating multi-joint dynamic contractions, 83% (11/13 studies) reported at least one significant age-related difference: In 84% (9/11 studies) coactivation was higher in children, whereas 16% (2/11 studies) reported higher coactivation in adults. Among single-joint contractions, only 25% (3/12 studies) reported significantly higher coactivation in children. Fifty six percent of studies examined females, with no clear sex-related differences. Child-adult differences in coactivation appear to be more prevalent during multi-joint dynamic contractions, where generally, coactivation is higher in children. When examining child–adult differences in muscle function, it is important to consider potential age-related differences in coactivation, specifically during multi-joint dynamic contractions.
2023-01-01T00:00:00ZThe September He Remembers
http://hdl.handle.net/10464/17130
The September He Remembers
Bolz, Cedric
The Summit Series, a best-on-best hockey tournament played between the former-Soviet and Canadian men’s teams, occupies an outsized role in the Canadian sporting imagination.
The September He Remembers: Josef Kompalla and the 1972 Summit Series reframes this famous Series in sport history through the story, experiences, and memories of Josef Kompalla, a German referee who played a key role in the events as one of the few esteemed officials selected to officiate during the Series. Given Kompalla’s important place in the history of the Summit Series, one of the most mythologized and celebrated tournaments in Canadian sport history, it should come as a surprise that his perspective on the events has not been previously documented. In this book, Bolz seeks to rectify this longstanding oversight through intrepid archival creation and analysis, as well as previously-untold stories from Kompalla himself.
Although Kompalla’s role in the Summit Series has been largely omitted or obfuscated for the past half century, The September He Remembers is finally the first step in correcting a major historical oversight and adding a new chapter in the Summit Series’ growing legacy.
2023-01-04T00:00:00ZProteomes Are of Proteoforms: Embracing the Complexity
http://hdl.handle.net/10464/16904
Proteomes Are of Proteoforms: Embracing the Complexity
Carbonara, Katrina; Andonovski, Martin; Coorssen, Jens R.
Proteomes are complex—much more so than genomes or transcriptomes. Thus, simplifying their analysis does not simplify the issue. Proteomes are of proteoforms, not canonical proteins. While having a catalogue of amino acid sequences provides invaluable information, this is the Proteome-lite. To dissect biological mechanisms and identify critical biomarkers/drug targets, we must assess the myriad of proteoforms that arise at any point before, after, and between translation and transcription (e.g., isoforms, splice variants, and post-translational modifications [PTM]), as well as newly defined species. There are numerous analytical methods currently used to address proteome depth and here we critically evaluate these in terms of the current ‘state-of-the-field’. We thus discuss both pros and cons of available approaches and where improvements or refinements are needed to quantitatively characterize proteomes. To enable a next-generation approach, we suggest that advances lie in transdisciplinarity via integration of current proteomic methods to yield a unified discipline that capitalizes on the strongest qualities of each. Such a necessary (if not revolutionary) shift cannot be accomplished by a continued primary focus on proteo-genomics/-transcriptomics. We must embrace the complexity. Yes, these are the hard questions, and this will not be easy…but where is the fun in easy?
2021-08-31T00:00:00Z