ECSS Paris 2023: CP-BM01
INTRODUCTION: Age-related declines in motor and gait function are associated with an increased risk of falls and reduced mobility in older adults. Lower-limb somatosensory input plays a critical role in gait regulation and postural control. Neuroimaging studies have further demonstrated that age-related impairment of plantar somatosensation is associated with increased prefrontal cortex activation during walking. However, the relationship between neurophysiological indices of somatosensory processing, such as somatosensory evoked potential (SEP), and gait function in older adults remain insufficiently understood. The purpose of this study was to examine the association between lower-limb SEP and gait function in older adults. METHODS: Fifty-one participants without dementia, of which 18 were men and 33 were women aged ≥65 years were recruited. SEP recordings were obtained following electrical stimulation of the tibial and peroneal nerves. Cortical SEP responses were recorded at the Cz electrode, and the latencies and amplitudes of the P37, N50, P60, and N70 components were analyzed. Motor and gait function were assessed during normal walking at a preferred speed, in addition to the Two-Step Test (2Step) as an index of gait capacity, the Timed Up and Go test (TUG) to evaluate functional mobility, and the Functional Reach (FR) test to assess dynamic balance performance. Correlation analyses were conducted to examine associations between SEP parameters and motor and gait outcomes using Pearson’s or Spearman’s correlation coefficients, as appropriate. RESULTS: Tibial nerve P37 latency and N50 amplitude were significantly correlated with 2Step values, indicating a relationship between early somatosensory cortical processing and gait. Peroneal nerve N70 latency was significantly associated with 2Step values, suggesting that later-stage somatosensory processing also contributes to gait performance. Peroneal nerve P60 amplitude was significantly correlated with TUG, while tibial nerve N70 amplitude showed a significant association with FR reach distance. CONCLUSION: These results suggest that age-related alterations in cortical somatosensory processing contribute to functional motor decline. Lower-limb SEP provides neurophysiological insight into sensory-motor integration underlying gait and balance in older adults. These findings demonstrate nerve-specific and component-specific relationships between SEP characteristics and different aspects of motor and gait function.
Read CV Kaede OharaECSS Paris 2023: CP-BM01
INTRODUCTION: In older adults, gait requires substantial cognitive processing and attentional regulation, and declines under dual-task (DT) conditions are closely linked to increased fall risk and loss of functional independence. Previous studies have shown that increased oxygenated hemoglobin (HbO) in the prefrontal cortex (PFC) during DT reflects compensatory recruitment of cognitive resources. However, significant individual differences exist in these neural responses. From a physical reserve perspective, it remains unclear how physical function indicators, such as muscle strength, relate to PFC activation during DT. This study investigated determinants of the difference in PFC HbO activation between single-task (ST) and DT and examined whether muscle strength moderates the relationship between dual-task cost (DTC) and neural response. METHODS: Gait performance (TUG 2-lap time) and PFC HbO (fNIRS) were measured in 59 community-dwelling older women (age: 77.93±6.60 years; educational years: 4.72±2.84; CIST: 19.67±6.67) during Timed Up and Go 2-lap ST and DT (verbal fluency task). The primary outcome was the difference in PFC activation between TUG DT and TUG ST(Delta_PFC_HbO). Independent variables included age, cognitive function (CIST), TUG-DTC, and upper-body (hand grip) and lower-body (30-second chair stand test) muscle strength. Multiple linear regression and hierarchical regression analyses were conducted to identify predictors of Delta_PFC_HbO and to test the moderating effects of strength (p < .05). RESULTS: Age significantly predicted the increase in PFC HbO activation during DT (B = 0.017, β = 0.418, p = .002), suggesting greater neural resource mobilization with advancing age. General cognitive function and behavioral DTC did not show significant associations with Delta_PFC_HbO. Handgrip strength showed a significant, independent association with Delta_PFC_HbO even after controlling for age, cognition, and TUG-DTC. No significant interaction or main effects were found for lower-body strength in the hierarchical regression models. PFC activation during DT was influenced by age, while handgrip strength independently explained individual differences in neural mobilization beyond behavioral performance. CONCLUSION: The major finding of this study was that while age-related increases in PFC HbO reflect compensation for reduced neural efficiency, strength-related increases reflect the capacity for neural resource mobilization. Aligning with the physical reserve perspective, our findings suggest that muscle strength, similar to cardiorespiratory reserve, represents a physiological capacity to recruit additional neural resources in response to task demands. Rather than simply alleviating task burden, muscle strength may determine the potential for neural compensation under cognitive-motor stress. Due to the cross-sectional design and specific sample profile (older women), future longitudinal studies are required to improve generalizability and clarify causal relationships.
Read CV Minju KimECSS Paris 2023: CP-BM01
INTRODUCTION: Non-contact anterior cruciate ligament (ACL) injuries are associated with dynamic knee valgus during jump tasks such as Drop Vertical Jump (DVJ). While the hamstrings play a crucial role in the dynamic stability of the knee joint, their assessment often does not adequately reflect the high-speed, coordinated capabilities required in actual sports movements. The Maximum-Speed Single-Leg Bridge Test (MS-SLBT) is a novel test for assessing the ability for fast, repetitive hip extension.1) This study aimed to clarify the relationship between the MS-SLBT metrics and knee kinematic parameters associated with ACL injury risk during the Singe-Leg DVJ (SL-DVJ). METHODS: 22 healthy male athletes (age: 21.0±1.5 years, height: 171±5.2 cm, mass: 64.5±6.1 kg) performed SL-DVJ from a 15 cm box and MS-SLBT on their dominant leg. MS-SLBT involves lying in a supine position, placing the heel on a 40 cm box, and raising the buttocks as fast and as high as possible for twenty repetitions.1) MS-SLBT metrics included peak buttock-raising height and speed, with mean values calculated for repetitions 2 to 19. SL-DVJ kinematics were measured using a 3D motion analysis system, calculating knee flexion/abduction and hip flexion angles at initial contact (IC), as well as peak knee flexion/abduction/internal rotation angles, peak hip flexion angle, and peak knee abduction/internal rotation moments within 0–50 ms post-IC. Spearman's rank correlation coefficient was used to assess the correlation between the MS-SLBT and the SL-DVJ metrics. The magnitude of the correlations was interpreted using Cohen's criteria as small (ρ ≥ 0.10), medium (ρ ≥ 0.30), and large (ρ ≥ 0.50). RESULTS: The buttock-raising height during the MS-SLBT showed a significant negative correlation of medium magnitude with peak knee abduction angle (ρ = −0.42, p < 0.05) and peak knee internal rotation angle (ρ = −0.42, p < 0.05) within 0-50 ms post-IC during the SL-DVJ. No significant correlations were found with any angles at IC or with other kinematic/kinetic variables at 0–50 ms. Furthermore, no buttock-raising speed metrics from any phase showed a significant correlation with any SL-DVJ metrics. CONCLUSION: This study showed that buttock-raising height in the MS-SLBT was associated with reduced knee abduction and internal rotation during the SL-DVJ. This suggests that the MS-SLBT buttock-raising height is involved in the dynamic control of the knee joint in the frontal and horizontal planes during landing. REFERENCE: 1) Sano Y, Kawabata M, Van Hooren B, Sumiya Y, Murase M, Watanabe Y, Shimono Y, Kenmoku T, Watanabe H, Takahira N. A practical assessment of hamstring muscle endurance and fatigue using the maximum-speed single-leg bridge test. BMC Sports Sci Med Rehabil. 2025 Dec 5;18(1):18.
Read CV Yuto WatanabeECSS Paris 2023: CP-BM01