Browsing by Author "Iannetta, Danilo"

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    An Unexpected Monetary Reward Enhances Endurance Exercise Performance but Results in Similar Isometric Neuromuscular Performance Fatigability Compared to a Non-Reward Session.
    (2023-09-07) Trpcic, Mackenzie; Murias, Juan; Aboodarda, Jalal; Holash, John; Iannetta, Danilo
    Extrinsic motivation via monetary reward incentivizes behavior. Data on how an incentivization encourages participants to push beyond their perceived limit are equivocal. This study aimed to determine if physically active, healthy, young adults could be influenced by an unexpected monetary reward to extend their time-to-task failure (TTF) cycling performance. Participants completed a control and reward TTF session in the heavy intensity domain of exercise (HVYTTF), and 1 min after, a TTF in the extreme domain (EXTTTF). The reward session involved an unexpected incentive offered 1 min before expected task failure during the HVYTTF. Neuromuscular (NM) assessments before and after the TTFs and the EXTTTF performance itself were used to evaluate performance fatigability. The unexpected incentive significantly increased the HVYTTF (46+/-16 min, 53+/-22 min; p =0.01) and reduced the EXTTTF (68+/-17 s, 57+/-17 s; p =0.03). Isometric NM assessments showed no condition effect or interactions. Significant time effects from baseline compared to post-HVYTTF and post-EXTTTF existed, respectively, for: i) IMVC: control, 601N, 414N, 413N (p <0.001); reward, 616N, 418N, 415N (p <0.001); ii) Db10:100: control, 0.99, 0.73, 0.70 (p <0.001); reward, 1.00, 0.74, 0.72 (p <0.001); and iii) Qtwpot: control, 177N, 109N, 110N (p <0.001); reward, 174N, 110N, 99N (p <0.001). VA showed no time effect from baseline to post-HVYTTF and post-EXTTTF: control, 90%, 90%, 87%; reward, 89%, 86%, 84%, respectively. These findings indicate that a monetary reward that increased the HVYTTF resulted in a reduced EXTTTF. The reduced performance during the dynamic task was not captured by isometric NM assessments.
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    Identifying exercise intensity "thresholds": Implications for metabolic responses, performance, and exercise intensity prescription.
    (2019-08-28) Iannetta, Danilo; Murias, Juan M.; Millet, Guillaume Y.; MacIntosh, Brian R.; Paterson, Donald Hugh; Bomhof, Marc R.; Vanhatalo, Anni
    The exercise intensity spectrum, from rest to maximal oxygen uptake (V̇O2max), can be partitioned into three domains of intensity: moderate, heavy, and severe. These domains are demarcated by the lactate threshold (LT) (moderate-to-heavy) and critical power (CP) or maximal lactate steady-state (MLSS) (heavy-to-severe), with the respiratory compensation point (RCP) of the ramp-incremental exercise also being proposed as a marker of the heavy-to-severe boundary of exercise intensity. Although the physiological concepts underpinning these thresholds are well established, methodological issues associated with their determination may lead to inaccuracies and contrasting interpretations regarding their equivalence. The general purpose of this thesis was to find solutions to some of the issues associated with the determination of these “thresholds” and demonstrate why their accurate determination is fundamental in exercise physiology. Using a variety of exercise protocols it was demonstrated that: i) current methods to compute the mean response time (MRT) of V̇O2 during ramp-exercise are inaccurate – the novel method proposed was valid and more reproducible than these methods; ii) exercising slightly above MLSS, although characterized in this study by a stable V̇O2 response, disproportionally impaired maximal exercise capacity; iii) if the V̇O2 dynamics during ramp-incremental exercise are carefully considered, the work rates at RCP and CP/MLSS are not different – refuting the idea that the RCP is not a valid surrogate of the heavy-to-severe boundary of exercise intensity; iv) current methods to prescribe exercise intensity based on fixed-percentage of maximum values (e.g., V̇O2max) do not provide an accurate procedure by which to control exercise intensity. Collectively, these findings provide solutions/explanations to some of the issues related to the correct identification of these exercise thresholds and suggest that their correct identification is of extreme importance when interpreting their physiological implications and to guarantee an accurate exercise intensity prescription.
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    Neuromuscular fatigue, cardiorespiratory, and perceptual responses are dependent on the amount of active muscle mass during exhaustive ramp incremental cycling
    (2021-09) Zhang, Mu Ye; Aboodarda, Saied Jalal; MacInnis, Martin; Iannetta, Danilo; Pageaux, Benjamin
    Exercise tolerance is determined by an integration of neuromuscular (NM), cardiorespiratory, and perceptual responses, the contributions and components of which differ according to the amount of muscle mass engaged in the exercise task. The present thesis aimed to utilize an exhaustive single- (SL) and double-leg (DL) ramp incremental cycling model to assess the effect of active muscle mass on NM fatigue and recovery kinetics alongside cardiorespiratory and perceptual responses. Twelve recreationally active males (age: 30 ± 5 years) performed counterweighted SL and DL ramp incremental cycling exercises to task failure. Central and peripheral fatigue were assessed at baseline, task failure, and 1, 4, and 8 min of recovery. Cardiorespiratory and perceptual responses were measured throughout the cycling tasks. The results from this study demonstrated that with similar exercise durations, maximal voluntary force and peripheral fatigue of the knee extensors declined more following SL cycling, along with increased perceived effort and leg pain. On the other hand, higher cardiorespiratory responses and dyspnea were evoked during DL cycling. Central fatigue and NM fatigue recovery did not largely differ between tasks. These findings suggest that the interplay between NM, cardiorespiratory, and perceptual determinants of exercise tolerance during incremental cycling to task failure is muscle mass-dependent. More specifically, while metabolic perturbations within working locomotor muscles (i.e., reflected in peripheral fatigue and muscle pain) are not the primary limiting factors during larger muscle mass exercise, they may instead play a primary role in modulating smaller muscle mass exercise tolerance. The present thesis may have implications on utilizing smaller muscle mass exercise in clinical and performance settings to enhance peripheral adaptations.
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    New Approaches to Investigate the Oxygen Cost of Exercise Applied to Human Performance
    (2024-09-09) Marinari, Gabriele; Murias, Juan M.; Iannetta, Danilo; Keir, Daniel A.; Holash, John R.; Porcelli, Simone; Aboodarda, Jalal
    During exercise, there is a tight control between anaerobic and aerobic energy sources to meet the demand in adenosine triphosphate (ATP) for energy provision. Oxidative phosphorylation provides ATP via aerobic energy sources assuming an adequate supply of oxygen (O2) to the active tissues is provided. When the intensity of exercise is within the heavy domain (i.e., above the gas exchange threshold (GET)), there is an increased O2 cost per unit of work (i.e., V̇O2 gain; G) which has commonly been attributed to the development of the oxygen uptake slow component (V̇O2SC), in connection to a lower exercise efficiency. Therefore, finding new strategies to (i) decrease the O2 cost of exercise, (ii) explore the dynamics of V̇O2, and (iii) enhance exercise performance and improve cardiovascular fitness assessment is paramount in the field of exercise physiology. The general purpose of this thesis was to contribute to addressing the issues highlighted above. By implementing different exercise protocols, we found that: (i) approaching a target heavy-intensity constant-work rate (WR) gradually via a progressive ramp increment decreases steady state V̇O2 and reduces the initial and steady state lactate concentration ([La-]) as opposed to a standard step-transition to the same WR; (ii) increasing total hemoglobin concentration ([TotHb]) before reaching the target heavy-intensity WR via a ramp decreases muscle activation and the interaction (i.e., the ratio) between muscle activation and [TotHb] aligned with V̇O2, suggesting a tight link between the interplay of these physiological parameters; (iii) priming exercise accelerates the overall subsequent ramp incremental (RI) V̇O2 response by shortening the mean response time (MRT), extends the V̇O2max plateau and increases peak power output (POpeak). Collectively, these findings provide new insights into the mechanisms leading to the increased O2 cost of exercise, the interplay between muscle hemodynamics and muscle activation with V̇O2, and the beneficial effects of priming exercise on RI test to improve cardiovascular fitness assessment.