ECSS Paris 2023: OP-BM20
INTRODUCTION: Tailored intervention programs consider individual characteristics and abilities of athletes or patients. Yet, we know little about how person-specific predispositions (e.g., phenotype) interact with task demands during skill practice. The supply-demand mismatch model (Lövden et al., 2010) predicts that optimal task demands (not too easy nor too difficult) expand current brain and behavioral capacities if exceeding intrinsic anatomical constraints (“supply”). While a moderate task difficulty during practice may enhance learning in old age, it is currently unclear how task demands interact with individual brain anatomy to modulate learning. Stabilometer balance learning (a seesaw-like platform) depends, in part, on genotype (Grossman, 1980) and is associated with individual differences in premotor cortical folding in young adults (Taubert et al., 2024). Cortical folding largely develops in utero and remain relatively stable throughout life (Storsve et al., 2014). Here we tested the effects of two different task demands (moderate vs. low) during practice and determined cortical folding patterns from brain MRI scans. We hypothesized that (1) both moderate vs. low task demands and higher premotor folding positively influence learning, moreover, (2) moderate task demands increase effects of cortical folding on learning (due to inherent performance limitations under high loads). METHODS: 61 healthy participants (mean age= 67.6 years, 36 females) were randomized into moderate or low task demand groups (manipulated through balance board mechanics) receiving five consecutive weeks of stabilometer practice. Both groups received three testing sessions (pre, inter, post), five practice sessions, and a baseline MRI session. The balance task was performed on a movable platform with a maximum deviation of ±26° (Lafayette Instrument). “Time in balance” was used to calculate improvements in performance after three (pre to inter) and five (pre to post) weeks of practice. Moderation analyses considered cortical folding in left premotor cortex as predictor (Taubert et al., 2024), group assignment (moderate vs. low task demands) as moderator whereas performance improvements after three (“early”) or five (“late”) weeks of training as dependent variables. RESULTS: Results revealed a significant direct effect of higher cortical folding on performance improvements during late (t=2.86, p=0.006) but not early (t=1.12, p=0.24) practice. Moderate compared to low task demands significantly enhanced improvements during both early (t=2.29, p=0.025) and late (t=3.04, p=0.004) learning. Finally, task demands moderated (interaction effect) the impact of cortical folding on early (t=2.03, p=0.047, rmoderate=.32, rlow=-.21) but not late performance improvements (t=1.585, p=0.119, rmoderate=.42, rlow=.12). CONCLUSION: Our findings extend the supply-demand mismatch model (Lövden et al., 2010) and show that, under sufficiently high task demands, neuroanatomical predispositions constrain performance improvements.
Read CV Marco TaubertECSS Paris 2023: OP-BM20
INTRODUCTION: Postural control relies upon the integration of visual, vestibular, and proprioceptive information. When the continuity of visual input is disrupted, the central nervous system must recalibrate sensory weighting to maintain stability. Stroboscopic vision provides a controlled method for investigating visual dependence by intermittently blocking visual information. Swimmers undergo prolonged underwater training in environments where visual cues are relatively unstable. However, whether this specialised setting influences their postural control abilities on land remains unexplored. This study aims to investigate the effects of acute flicker visual interference on the dynamic and static balance performance of university swimmers. METHODS: Twenty national-level swimmers of Grade II or above completed a within-subjects repeated measures experiment. Participants underwent testing under baseline open-eye conditions and at three flicker levels (Level 2: 5 Hz, Level 4: 3 Hz, Level 6: 1.75 Hz). Dynamic balance was assessed using the Y-Balance Test, recording normalised reach distance and composite scores for anterior, posterior medial, and posterior lateral directions. Static balance was evaluated via force plate measurements of COP trajectory length, mean velocity, and ML/AP directional velocities. Test conditions were randomised in sequence with balanced scheduling, featuring 3-minute rest periods between conditions. Statistical analysis employed repeated measures ANOVA with a significance level of 0.05. RESULTS: Results indicate that under stroboscopic conditions, bilateral forward normalised reach distances were significantly lower than baseline open-eye measurements (left side F=8.418, right side F=7.556, both p<0.01). No significant differences were observed in posterior medial or posterior lateral directions, nor were there notable changes in composite scores. Regarding static balance, flicker significantly increased COP trajectory length and mean velocity (F=8.700 and 8.707, p<0.01), while ML and AP directional velocities also markedly increased (p<0.01). Differences between flicker levels were non-significant for most metrics. CONCLUSION: Overall, acute visual flicker interference impairs the terrestrial balance performance of university swimmers, particularly manifesting as reduced forward dynamic control and increased static postural sway. Despite swimmers' prolonged exposure to visually unstable underwater environments, their terrestrial postural regulation remains highly dependent on visual continuity. These findings provide novel evidence for understanding the relationship between aquatic specialisation adaptations and terrestrial postural control. They also suggest that when employing visual disturbances in training or assessment, the intensity and progression methods should be carefully controlled.
Read CV Yufeng TangECSS Paris 2023: OP-BM20
INTRODUCTION: A menstrual cycle (MC) is characterized by fluctuation of ovarian hormones, progesterone (P4) and estradiol (E2). The influence of sex hormones in neural responses at the cortical level has been demonstrated in several studies, where voluntary activation has been observed to increase together with higher concentrations of the neuroexcitatory hormone E2 during the late-follicular phase (LF) [1], and increased central inhibition measured with conditioned MEP has been observed during the mid-luteal phase (ML), coinciding with high concentrations of neuroinhibitory P4 [2]. However, the influence of ovarian hormones on spinal excitability is less investigated, studies reporting decreased presynaptic inhibition concurrent with higher concentrations of E2 at ovulatory phase [3] or no changes at all [4]. Importantly, most studies have been conducted in prone or seated positions, failing to capture the principles of bipedal motor control. The purpose of this study was to examine the influence of MC-related fluctuation of ovarian hormones on neural responses during dynamic balance perturbations. METHODS: Ten normally menstruating females (31±7 yrs) were measured at the EF (early-follicular), LF and ML phases of the MC. Venous blood samples were taken on the morning of each test and analyzed retrospectively. A custom-built dynamic balance platform was used to induce perturbations on a horizontal plane in anterior-posterior direction. Spinal excitability and neural drive were measured from soleus-muscle at four latencies from the onset of perturbation (40, 70, 100 and 130 ms) using H-reflex and V-wave techniques, respectively. RESULTS: A significant main effect of MC was observed for both H-reflex (F=3.559; p=0.032) and V-wave (F=3.917; p=0.023) responses. H-reflex was at its lowest at ML, pairwise comparison showed significant overall differences between EF and ML (p=0.027) and LF and ML (p=0.020), but not between EF and LF (p=0.903). Similarly, V-wave was lower at ML compared to EF (p=0.015) and LF (p=0.020), but no differences in V-wave were observed between EF and LF (p=0.900). CONCLUSION: This study suggests that spinal excitability and neural drive during dynamic balance perturbations are influenced by MC phase, which may be related to fluctuation in ovarian hormones. Consistent with previous studies [1,2], higher concentrations of P4 were observed to accompany reduced neural drive, but also decreased spinal excitability, which may reflect the neuroinhibitory mechanism of P4. 1. Ansdell P, Brownstein CG, Škarabot J, Hicks KM, Simoes DC, Thomas K, Goodall S. J Appl Physiol 2019; 126(6), 1701-1712. 2. Smith MJ, Keel JC, Greenberg BD, Adams LF, Schmidt PJ, Rubinow DA, Wassermann EM. Neurol. 1999;53(9):2069–72. 3. Hoffman MA, Doeringer JR, Norcross MF, Johnson ST, Chappell PE. Scand J Med Sci Sports 2018; 28:2009–2015. 4. Casey E, Reese M, Okafor E, Chun D, Gagnon C, Nigl F, Dhaher YY. PM&R 2016; 8(9), 860–868.
Read CV Samuli NevanperäECSS Paris 2023: OP-BM20