Kinesiology
http://hdl.handle.net/10464/5751
2024-03-18T17:30:28ZPost-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.
2023-01-01T00:00:00ZCharacterization of sclerostin’s response within white adipose tissue to an obesogenic diet at rest and in response to acute exercise in male mice
http://hdl.handle.net/10464/16731
Characterization of sclerostin’s response within white adipose tissue to an obesogenic diet at rest and in response to acute exercise in male mice
Kurgan, Nigel; Baranowski, Bradley; Stoikos, Joshua; MacNeil, Adam J.; Fajardo, Val A.; MacPherson, Rebecca EK; Klentrou, Panagoita
This study examined the effect of a high-fat diet (HFD) on sclerostin content within subcutaneous inguinal visceral white adipose tissue (iWAT), and visceral epididymal WAT (eWAT) depots at rest and in response to acute aerobic exercise. Male C57BL/6 mice (n=40, 18 weeks of age) underwent 10 weeks of either a low-fat diet (LFD) or HFD. Within each diet group, mice were assigned to either remain sedentary (SED) or perform 2h of endurance treadmill exercise at 15 m·min-1 with 5° incline (EX), creating 4 groups: LFD+SED (N=10), LFD+EX (N=10), HFD+SED (N=10), and HFD+EX (N=10). Serum and WAT depots were collected 2h post-exercise. Serum sclerostin showed a diet-by-exercise interaction, reflecting HFD+EX mice having higher concentration than HFD-SED (+31%, p=0.03), and LFD mice being unresponsive to exercise. iWAT sclerostin content decreased post-exercise in both 28 kDa (-31%, p=0.04) and 30 kDa bands (-36%, main effect for exercise, p=0.02). iWAT b-catenin (+44%, p=0.03) and GSK3b content were elevated in HFD mice compared to LFD (+128%, main effect for diet, p=0.005). Monomeric sclerostin content was abolished in eWAT of HFD mice (-96%, main effect for diet, p<0.0001), was only detectable as a 30 kDa band in LFD mice and was unresponsive to exercise. b-catenin and GSK3b were both unresponsive to diet and exercise within eWAT. These results characterized sclerostin’s mobilization to WAT depots in response to acute exercise, which appears to be specific to a reduction in iWAT and identified a differential regulation of sclerostin’s form/post-translational modifications depending on diet and WAT depot.
2022-01-01T00:00:00ZAssociation of Functional Screening Tests and Noncontact Injuries in Division I Women Student-Athletes
http://hdl.handle.net/10464/15178
Association of Functional Screening Tests and Noncontact Injuries in Division I Women Student-Athletes
Warren, Meghan; Lininger, Monica R.; Smith, Craig A.; Copp, Adam J.; Chimera, Nicole J.
To determine the association between functional screening tests and lower-body, noncontact injuries in Division I women basketball, soccer, and volleyball student-athletes (SA). Sixty-eight injury-free women SA (age19.1 ± 1.1 years, height171.3 ± 8.7 cm, and mass68.4 ± 9.5 kg) were tested preseason with single hop (SH), triple hop (TH), and crossover hop (XH) for distance, and isometric hip strength (abduction, extension, and external rotation) in randomized order. The first lower-body (spine and lower extremity), noncontact injury requiring intervention by the athletic trainer was abstracted from the electronic medical record. Receiver operating characteristic and area under the curve (AUC) were calculated to determine cut-points for each hopping test from the absolute value of between-limb difference. Body mass–adjusted strength was categorized into tertiles. Logistic regression determined the odds of injury with each functional screening test using the hopping tests cut-points and strength categories, adjusting for previous injury. Fifty-two SA were injured during the sport season. The cut-point for SH was 4 cm (sensitivity = 0.77, specificity = 0.43, and AUC = 0.53), and for TH and XH was 12 cm (sensitivity = 0.75 and 0.67, specificity = 0.71 and 0.57, AUC = 0.59 and 0.41, respectively). A statistically significant association with TH and injuries (adjusted odds ratio = 6.50 [95% confidence interval1.69–25.04]) was found. No significant overall association was found with SH or XH, nor with the strength tests. Using a clinically relevant injury definition, the TH showed the strongest predictive ability for noncontact injuries. This hopping test may be a clinically useful tool to help identify increased risk of injury in women SA participating in high-risk sports.
2020-01-01T00:00:00Z