Biology subjects

Youssef, L.

Publications and source records attributed to Youssef, L..

5 recordsLinked to original sources

bioRxiv2025

Effects of experimentally induced fatigue on motor learning: A scoping review

The literature on the effect of fatigue on motor learning is limited and marked by inconsistent findings. This scoping review aimed to explore the available knowledge on the effects of fatigue induced by physical and cognitive exertion on motor learning, and to compile and understand how it is studied. A comprehensive search strategy using relevant index terms and keywords was conducted across MEDLINE, EMBASE, SPORTDiscus, Web of Science, PsycINFO, CINAHL, ERIC, and Dissertations & Theses Global. Twenty-five studies met the inclusion criteria. The findings revealed considerable inconsistencies in how fatigue and motor learning were defined and measured. None of the studies examined the effect of fatigue induced by combined physical and cognitive exertion, and only 7 studies investigated fatigue induced by cognitive exertion. Acuity tasks were the most frequently used to assess motor learning, employed in 14 studies. Notably, all participants were between 16.5 and 31 years of age, and reporting of key demographic and physiological characteristics such as sex, gender, physical activity level, and body mass index was inconsistent or absent. This review highlights the need for comprehensive definitions of both fatigue and motor learning to improve consistency and reproducibility across studies. Given the limited research on the effects of fatigue induced by cognitive and combined physical and cognitive exertion, future studies should prioritize using these experimental manipulations. Also, future studies should diversify the motor learning tasks used in research to allow both direct and conceptual replication. Additionally, broader age ranges and comprehensive participant profiling should be prioritized.

neuroscience↗

bioRxiv2025

Physical exercise and motor learning: A scoping review

Physical exercise can enhance motor learning by inducing neurophysiological changes that facilitate this process. This preregistered scoping review aimed to map current knowledge on the effects of physical exercise on motor learning. Experimental studies and review articles examining any form of physical exercise in healthy or clinical populations were included, with outcomes assessing motor skill acquisition and/or retention. A systematic search across eight databases (e.g., MEDLINE, EMBASE, PsychINFO) identified 66 sources, including 62 experimental studies and 4 reviews. Two researchers independently reviewed articles and extracted data using a pretested data extraction table; disagreements at the study selection or data extraction stages were resolved through discussion with a third researcher. Most studies involved healthy populations (83%), with clinical populations underrepresented (17%). Aerobic exercise was most commonly investigated, particularly lower-limb cycling (73%), while resistance exercise was rarely examined (0.6%). Exercise intensity was predominantly high, although 6% of studies reported intensity not reflecting the prescribed method. Motor learning outcomes varied: 55% assessed both skill acquisition and retention, while 45% relied on retention tests alone at short-term or delayed time points, or both. Infrequent use of long-term retention tests limits understanding of lasting effects. Overall, this review highlights gaps in the literature, including the underrepresentation of clinical populations, inconsistent reporting of exercise intensity, scarce research on resistance exercise, and limited assessment of long-term retention, which may affect interpretation of exercises impact on motor learning. HighlightsO_LIClinical populations were underrepresented in the exercise and motor learning field. C_LIO_LIHigh-intensity lower-limb cycling was the most common exercise studied. C_LIO_LIResistance exercise was underrepresented in the field. C_LIO_LIAccurate prescription of exercise intensity is essential to ensure reliable results. C_LIO_LIFuture research should more frequently use longer-term retention tests. C_LI

neuroscience↗

bioRxiv2025

Eccentric cycling enhances primary motor cortex excitability

Acute aerobic exercise (AAE) can modulate primary motor cortex (M1) excitability. To date, studies evaluating its effects have focused almost exclusively on concentric cycling. Critically, we found that eccentric AAE enhances motor learning more than concentric AAE, possibly explained by enhanced frontal-parietal brain activation during eccentric cycling. Yet, M1 excitability mechanisms underlying this eccentric AAE-enhanced motor learning remain unknown. Thus, this study aimed to evaluate the effect of eccentric cycling AAE on M1 excitability using transcranial magnetic stimulation (TMS). Thirty adults performed three 20 min-conditions: i) eccentric cycling AAE, ii) concentric cycling AAE, and iii) rest. Cycling AAE was carried out at a workload corresponding to 70% of peak heart rate (%HRpeak) measured during concentric incremental cycling exercise. TMS assessments were conducted before (Pre), immediately (Post0) and 20 minutes after (Post20) AAE/rest to evaluate changes in corticospinal excitability (CSE) and short-interval intracortical inhibition (SICI). Overall, we found CSE increased and intracortical inhibition (SICI) was reduced at Post20 to a comparable extent following eccentric and concentric cycling AAE compared to rest. Also, %HRpeak, muscle pain and perceived effort were lower during eccentric cycling AAE compared to concentric cycling AAE. Our results showed that eccentric cycling impacted M1 excitability change to a comparable degree as concentric cycling, while requiring less cardiovascular response, eliciting less muscle pain and lower perceived effort. Taken together, our results suggest that eccentric cycling AAE may be a valuable intervention to modulate M1 excitability for populations with limited cardiovascular capacity and may have potential implications in clinical and sports-related contexts.

neuroscience↗

bioRxiv2025

Eccentric cycling improves motor learning more than concentric cycling

An acute bout of aerobic exercise (AAE) performed before practicing a motor task can enhance skill acquisition and motor learning. To date, research on the effects of AAE on motor learning has focused exclusively on concentric cycling, leaving the impact of eccentric cycling unexplored. Unlike concentric cycling, eccentric cycling involves muscle lengthening while resisting the reverse movement of the pedals and is characterized by greater force production with lower cardiovascular and metabolic cost. Regarding neuroplasticity changes, eccentric contractions induced a prolonged decrease in intracortical inhibition compared to concentric contractions. Eccentric cycling AAE also increases activation in cognitive-related regions. Given the involvement of these regions and motor cortex excitability in motor learning, we hypothesized that eccentric cycling AAE would enhance motor learning to a greater extent than concentric AAE. A total of 60 young healthy individuals were allocated to one of three groups that performed 20 min of: i) eccentric cycling; ii) concentric cycling; or iii) seated rest. Both cycling AAE conditions were performed at a power equivalent to 70% peak heart rate (i.e., moderate intensity). A continuous tracking task was used to assess motor skill acquisition (immediately after the intervention) and motor learning (48 h retention test). For both acquisition and retention, the eccentric group outperformed both the concentric and rest groups, while the concentric group also showed a better performance compared to the rest group at retention. Thus, we demonstrated that eccentric cycling AAE enhances motor learning to a greater extent than concentric cycling AAE, while also confirming previous work that showed enhanced motor learning following concentric cycling AAE compared to rest. Our findings suggest that eccentric cycling AAE may have important implications for exercise protocols prescribed in sports-related and clinical contexts. HighlightsO_LIEccentric cycling enhanced motor learning to a greater extent than concentric cycling C_LIO_LIEccentric and concentric cycling enhanced motor learning more than rest C_LIO_LIEnhanced skill acquisition occurred after eccentric cycling, along with lower heart rate response and perceived effort. C_LIO_LIEccentric cycling may have important implications in sports-related and clinical contexts C_LI

neuroscience↗

bioRxiv2025

Motor cortical circuits are uniquely impacted by different exercise intensities

Acute aerobic exercise (AEX) can enhance motor learning and promote neuroplasticity. However, the effect of AEX intensity on primary motor cortex (M1) excitability has not been systematically examined. Hence, the dose-response relationship between AEX intensity and M1 excitability modulation remains unclear. This study investigated the impact of AEX intensity on distinct M1 circuits using transcranial magnetic stimulation (TMS). Thirty right-handed adults underwent four experimental sessions: rest (control), light (LIIT), moderate (MIIT), and high-intensity interval training (HIIT) AEX. AEX intensity was prescribed with the heart rate reserve (HRR) method, and the interval cycling sessions consisted of alternating between 3 min at the target intensity (LIIT: 35% HRR; MIIT: 55% HRR; HIIT: 80% HRR) and 2 min of active recovery (25% HRR) for 20 min total. We performed TMS measures before (Pre), immediately post (Post0), and 20 min post (Post20) AEX/rest to assess modulation of corticospinal excitability and GABAergic inhibition as measured by short interval-intracortical inhibition (SICI). This study found that: (1) HIIT and MIIT increased corticospinal excitability, with HIIT eliciting a sustained increase; and (2) all AEX intensities (LIIT, MIIT and HIIT) decreased SICI, with the greatest sustained reduction following MIIT. Also, there was a greater reduction in GABAergic inhibition when measured with anterior-posterior than posterior-anterior TMS current following MIIT. Collectively, our results demonstrate the impact of HIIT and MIIT to enhance corticospinal excitability and reduce GABAergic inhibition in M1. This study provides evidence for a dose-response effect of AEX intensity on the modulation of distinct motor cortical circuits. KEY POINTS SUMMARYO_LIAcute aerobic exercise (AEX) is known to modulate primary motor cortex (M1) excitability, but the effect of AEX intensity is unclear. C_LIO_LIThis study examined the impact of light-, moderate-, and high-intensity interval training (LIIT, MIIT, HIIT) AEX and rest (non-AEX, control) on distinct M1 cortical circuits using transcranial magnetic stimulation (TMS). C_LIO_LIHIIT induced a sustained increase in M1 output excitability, MIIT induced a transient increase, and LIIT showed no effect. C_LIO_LIAll exercise intensities (LIIT, MIIT and HIIT) decreased GABAergic inhibition, as measured by short-interval intracortical inhibition (SICI), with MIIT showing a sustained decrease. C_LIO_LISICI measured with an anterior-to-posterior TMS current demonstrated greater GABAergic disinhibition compared to posterior-to-anterior TMS current following MIIT. C_LIO_LIThis study demonstrates a nuanced dose-response impact of AEX intensity on distinct M1 cortical circuits. C_LI

neuroscience↗