The aim of this study was to demonstrate a time-series relationship in drop jump (DJ) from a pre-set state with improved performance. Twelve male college athletes performed a DJ from a height of 0.60 m. DJ performance was assessed with a DJ-index (jump height/contact time). Short-interval intracortical inhibition (SICI) was assessed as intracortical inhibitory circuit excitability in a pre-set state, calculated by using paired-pulse transcranial magnetic stimulation for the medial gastrocnemius muscle (MG). The H-reflex of the left MG and the ankle joint torque were calculated in the early phase of take-off. A significant correlation was shown between ⊿SICI during the pre-set state and the DJ index. Thus, we examined the relationships between phases, focusing on time-series relationships throughout the jump period. The results showed a significant correlation between ⊿SICI during the pre-set state and %H-reflex during the early phase of take-off, and peak ankle joint torque during take-off was also significantly correlated with %H-reflex during the early phase of take-off. A significant correlation was also demonstrated between ankle joint torque during take-off and the DJ-index. In conclusion, we observed a time-series relationship between DJ from a pre-set state and improved performance. A decrease of intracortical inhibitory circuit excitability in the pre-set state affects stretch-reflex facilitation during the early phase of take-off; stretch-reflex facilitation results in the development of a large force in the ankle joint during take-off, and this force develops ankle joint torque. These findings may be used to improve jump performance.

BACKGROUND: The Fujiwara-kyo Osteoporosis Risk in Men (FORMEN) study was launched to investigate risk factors for osteoporotic fractures, interactions of osteoporosis with other non-communicable chronic diseases, and effects of fracture on QOL and mortality. METHODS: FORMEN baseline study participants (in 2007 and 2008) included 2012 community-dwelling men (aged 65-93 years) in Nara prefecture, Japan. Clinical follow-up surveys were conducted 5 and 10 years after the baseline survey, and 1539 and 906 men completed them, respectively. Supplemental mail, telephone, and visit surveys were conducted with non-participants to obtain outcome information. Survival and fracture outcomes were determined for 2006 men, with 566 deaths identified and 1233 men remaining in the cohort at 10-year follow-up. COMMENTS The baseline survey covered a wide range of bone health-related indices including bone mineral density, trabecular microarchitecture assessment, vertebral imaging for detecting vertebral fractures, and biochemical markers of bone turnover, as well as comprehensive geriatric assessment items. Follow-up surveys were conducted to obtain outcomes including osteoporotic fracture, cardiovascular diseases, initiation of long-term care, and mortality. A complete list of publications relating to the FORMEN study can be found at https://www.med.kindai.ac.jp/pubheal/FORMEN/Publications.html .
Aged ; Bone Density ; Cardiovascular Diseases/etiology* ; Cohort Studies ; Geriatric Assessment ; Humans ; Independent Living ; Japan/epidemiology* ; Long-Term Care/statistics & numerical data* ; Male ; Middle Aged ; Osteoporosis/etiology* ; Osteoporotic Fractures/etiology* ; Risk Factors