Characteristics of resting state functional connectivity of motor cortex of high fitness level college students: Experimental evidence from functional near infrared spectroscopy (fNIRS).

OBJECTIVE: This study inspects difference of resting state functional connectivity (RSFC) of motor cortex between athletes and ordinary college students and the test-retest reliability of RSFC. METHODS: Twenty high fitness level college students (high fitness group) and 20 ordinary college students (control group) were recruited. The motor cortical blood oxygen signals in resting states were monitored by functional near infrared spectroscopy (fNIRS). RSFCs of brain signals were preprocessed and calculated by FC-NIRS software. RSFC results of test-retest reliability were evaluated by intra-class correlation coefficient (ICC). RESULTS: Total RSFC (HbO signal) was significantly different between high fitness group (0.62 ± 0.04) and low fitness group (0.81 ± 0.04) (p < .05). Significant differences were found between the groups (HbO signal) in 50 edges among the 190 edges of motor cortex (14 edges after FDR corrected). At three hemoglobin concentrations, mean of group-level ICC (C, 1) for total RSFC in two groups was 0.40 ± 0.10, whereas the mean of group-level ICC (C, k) was 0.57 ± 0.11, depicting "fair" reliability. The mean of group-level ICC (C, 1) of 190 "edges" was 0.88 ± 0.06, whereas mean of ICC (C, k) was 0.94 ± 0.03, exhibiting "excellent" reliability. CONCLUSION: Fitness level is the factor causing specific changes in RSFC strength of motor cortex that can be utilized as biomarker for evaluating the fitness level.

Exploring Sex Differences and Force Level Effects on Grip Force Perception in Healthy Adults.

This study aimed to explore the effect of sex and force level on grip force reproduction in healthy adults by conducting a force reproduction task. Participants (n = 28) were instructed to replicate a range of reference grip force levels (10-130 N in 10 N increments). We found that women (absolute error: 16.2 ± 8.7 N) replicated these force levels more accurately than men (absolute error: 23.1 ± 9.5 N) at higher force levels (90-130 N). Furthermore, the force reproductions were most accurate at the 30-50 N range for men and the 50-60 N range for women. These results may offer significant insights into the higher rates of musculoskeletal disorders among women, enabling researchers and clinicians to design novel interventions and tools that can improve grip force perception and reduce hand injury rates in both men and women.