Browsing by Author "Aboodarda, Saied J"

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    The Influence of Carbohydrate Availability on Exercise Performed at the Maximal Lactate Steady State
    (2022-01-17) Quinn, Colton P; MacInnis, Martin J; Murias, Juan M; MacInnis, Martin J; Murias, Juan M; Aboodarda, Saied J; Reimer De Bruyn, Raylene A; Hazell, Tom J
    The impact of carbohydrate (CHO) availability on time to task failure (TTF) and key physiological responses to exercise at the maximal lactate steady state (MLSS) has not been studied. The primary objective of this thesis was to determine how various levels of CHO availability affected TTF at MLSS. The secondary objectives of this thesis were to explore how changes in CHO availability impacted i) [BLa] and CHO oxidation rates at MLSS and ii) neuromuscular fatigue (NMF) and subjective ratings of fatigue and exertion when exercise is performed at MLSS. A combination of nutritional (carbohydrate [CHO] and placebo [PLA]) and exercise interventions (no exercise [REST] and glycogen depletion [GD]) created four conditions with distinct levels of CHO availability at the time of data collection (RESTCHO > RESTPLA > GDCHO > GDPLA). Specifically, CHO and PLA involved consuming beverages containing 7g or 0g of CHO per kg of body mass, respectively, and REST and GD involved no exercise intervention or a glycogen depletion intervention the evening prior to data collection, respectively. Ten participants (4 females, 6 males) completed this double blinded study. TTF at MLSS was not improved by CHO loading, as RESTCHO (57.1 ± 15.8 min) and RESTPLA (57.1 ± 14.8 min) were not significantly different (p = 1.0); however, TTF was significantly reduced in both GD conditions (p < 0.05), and GDCHO (39.1 ± 8.8 min) had a significantly longer TTF compared to GDPLA (20.6 ± 6.5 min; p < 0.001). Pre-TTF to post-TTF changes in NMF variables were not significantly different between conditions despite the large differences in TTF (p> 0.05). Further, at task failure, there was no significant differences in subjective ratings of fatigue and exertion (p > 0.05); however, prior to the TTF trial, participants reported significantly higher ratings of fatigue in GD conditions compared to rest conditions (p < 0.001), with no significant difference between GD conditions (p > 0.05). Finally, the magnitude of some physiological variables (i.e. [BLa] and RER) were impacted by CHO availability, but the pattern of these responses remained unchanged. These findings indicate that changes in CHO availability hinder MLSS determination through a reduction in TTF (i.e., inability to cycle for 30 min continuously), not via changes in metabolic responses to exercise at MLSS (i.e., [BLa] was stable in all conditions).
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    ItemOpen Access
    The short-term recovery of corticomotor responses in elbow flexors
    (2019-03-14) Aboodarda, Saied J; Fan, Selina; Coates, Kyla; Millet, Guillaume Y
    Abstract Background The recovery of neurophysiological parameters at various time intervals following fatiguing exercise has been investigated previously. However, the repetition of neuromuscular assessments during the recovery period may have interfered with the true corticomotor excitability responses. In this experiment, fatiguing contractions were combined with a single post-fatigue assessment at varying time points. Ten participants undertook 5 bouts of 60-s maximal voluntary contractions (MVC) of the elbow flexors, separated by 20 min. Before and after each 60-s fatiguing exercise (FAT), participants performed a series of 6-s contractions at 100, 75 and 50% of their MVC during which transcranial magnetic, transmastoid electrical and brachial plexus electrical stimuli were used to elicit motor evoked potentials (MEP), cervicomedullary motor evoked potentials (CMEP) and compound muscle action potentials (Mmax) in the biceps brachii muscle, respectively. Post-FAT measurements were randomly performed 0, 15, 30, 60, or 120 s after each FAT. Results MVC force declined to 65.1 ± 13.1% of baseline following FAT and then recovered to 82.7 ± 10.2% after 60 s. The MEP·Mmax−1 ratio recorded at MVC increased to 151.1 ± 45.8% and then returned to baseline within 60 s. The supraspinal excitability (MEP·CMEP−1) measured at MVC increased to 198.2 ± 47.2% and fully recovered after 30 s. The duration of post-MEP silent period recorded at MVC elongated by 23.4 ± 10.6% during FAT (all P < 0.05) but fully recovered after 15 s. Conclusions The current study represents the first accurate description of the time course and pattern of recovery for supraspinal and spinal excitability and inhibition following a short maximal fatiguing exercise in upper limb.
  • Thumbnail Image
    ItemOpen Access
    The short-term recovery of corticomotor responses in elbow flexors
    (2019-03-14) Aboodarda, Saied J; Fan, Selina; Coates, Kyla; Millet, Guillaume Y
    Abstract Background The recovery of neurophysiological parameters at various time intervals following fatiguing exercise has been investigated previously. However, the repetition of neuromuscular assessments during the recovery period may have interfered with the true corticomotor excitability responses. In this experiment, fatiguing contractions were combined with a single post-fatigue assessment at varying time points. Ten participants undertook 5 bouts of 60-s maximal voluntary contractions (MVC) of the elbow flexors, separated by 20 min. Before and after each 60-s fatiguing exercise (FAT), participants performed a series of 6-s contractions at 100, 75 and 50% of their MVC during which transcranial magnetic, transmastoid electrical and brachial plexus electrical stimuli were used to elicit motor evoked potentials (MEP), cervicomedullary motor evoked potentials (CMEP) and compound muscle action potentials (Mmax) in the biceps brachii muscle, respectively. Post-FAT measurements were randomly performed 0, 15, 30, 60, or 120 s after each FAT. Results MVC force declined to 65.1 ± 13.1% of baseline following FAT and then recovered to 82.7 ± 10.2% after 60 s. The MEP·Mmax−1 ratio recorded at MVC increased to 151.1 ± 45.8% and then returned to baseline within 60 s. The supraspinal excitability (MEP·CMEP−1) measured at MVC increased to 198.2 ± 47.2% and fully recovered after 30 s. The duration of post-MEP silent period recorded at MVC elongated by 23.4 ± 10.6% during FAT (all P < 0.05) but fully recovered after 15 s. Conclusions The current study represents the first accurate description of the time course and pattern of recovery for supraspinal and spinal excitability and inhibition following a short maximal fatiguing exercise in upper limb.