ARTICLE | doi:10.20944/preprints202205.0040.v1
Subject: Physical Sciences, Other Keywords: jump header shooting; soccer, trunk muscle activity; stabilization exercise
Online: 5 May 2022 (12:38:08 CEST)
Background: This study aimed to clarify trunk muscle activity during jump header shooting and examine the immediate effects of trunk stabilization exercises on trunk muscle activity. Methods: Nineteen male college students who had played soccer in junior high and high school clubs and youth sports teams for over 5 years were assigned to either the trunk stabilization exercise group (n = 10) or the control group (n = 9). Muscle activity during jump header shooting was measured before and after intervention. The intervention in the trunk stabilization exercise group was trunk muscle training, whereas that in the control group was sitting. The phases of jump header shooting and the effects of the interventions were compared. Results: The internal oblique activity during the push-off phase and early floating phase was significantly greater than that during the late floating phase. The muscle activity of the internal oblique increased from the push-off phase, prior to the increase in muscle activity of the rectus abdominis and external oblique, whereas the muscle activity of all abdominal muscles increased immediately after take-off. The trunk stabilization exercise intervention decreased the muscle activity of the erector spinae during jump header shooting. Conclusions: These results provide useful coaching-related insights for jump header shooting.
ARTICLE | doi:10.20944/preprints202204.0179.v1
Subject: Physical Sciences, Other Keywords: anterior knee laxity; stiffness; general joint laxity; genu recurvatum
Online: 19 April 2022 (10:28:50 CEST)
The purpose of this study was to investigate the changes in anterior knee laxity (AKL), stiffness, general joint laxity (GJL), and genu recurvatum (GR) during the menstrual cycle in female non-athletes and female athletes with normal and irregular menstrual cycles. Participants were 19 female non-athletes (eumenorrhea, n=11; oligomenorrhea, n=8) and 15 female athletes (eumenorrhea, n=8; oligomenorrhea, n=7). AKL was measured as the amount of anterior tibial displacement at 67 N - 133 N. Stiffness was calculated as change in (Δ)force/Δ anterior displacement. The Beighton method was used to evaluate the GJL. The GR was measured as the maximum angle of passive knee joint extension. AKL, stiffness, GJL, and GR were measured twice in four phases during the menstrual cycle. Stiffness was significantly higher in oligomenorrhea groups than in eumenorrhea groups, although no significant differences between menstrual cycle phases were evident in female non-athletes. GR was significantly higher in the late follicular, ovulation, and luteal phases than in the early follicular phase, although no significant differences between groups were seen in female athletes. Estradiol may affect the stiffness of the periarticular muscles in the knee, suggesting that GR in female athletes may change during the menstrual cycle.
ARTICLE | doi:10.20944/preprints202301.0158.v1
Subject: Physical Sciences, Other Keywords: subtalar joint instability; chronic ankle instability; footprint osteoarthritis
Online: 9 January 2023 (09:22:22 CET)
This study aimed to clarify the relationship between the joint and ligament structures of the subtalar joint and degeneration of the subtalar articular facet. We examined 50 feet from 25 Japanese cadavers. The number of articular facets, joint congruence, and intersecting angle were measured for the joint structure of the subtalar joint, and the footprint areas of the ligament attachments of the cervical ligament, interosseous talocalcaneal ligament (ITCL), and anterior capsular ligament were measured for the ligament structure. Also, subtalar joint facets were classified into Degeneration (+) and (-) groups according to degeneration of the talus and calcaneus. No significant relationship was identified between the joint structure of the subtalar joint and degeneration of the subtalar articular facet. In contrast, footprint area of the ITCL was significantly higher in the Degeneration (+) group than in the Degeneration (-) group for the subtalar joint facet. These results suggest that the joint structure of the subtalar joint may not affect degeneration of the subtalar articular facet. Degeneration of the subtalar articular facet may be related to the size of the ITCL.
ARTICLE | doi:10.20944/preprints202301.0146.v1
Subject: Physical Sciences, Other Keywords: menstrual cycle; mechanical properties; stiffness; estradiol; musculotendon complex
Online: 9 January 2023 (06:50:28 CET)
The purpose of this study was to determine changes in the mechanical properties of the thigh and lower leg musculature during the early follicular and ovulatory phases. Subjects were 15 female university students with normal menstrual cycles. The early follicular and ovulatory phases were estimated by the basal body temperature method, ovulation kits, and salivary estradiol concentration measurement. The MyotonPRO digital palpation device (Myoton AS, Tallinn, Estonia) was used to measure muscle and tendon stiffness in the early follicular and ovulatory phases. Measurement sites were the rectus femoris (RF), vastus medialis (VM), patellar tendon (PT), medial head of gastrocnemius, soleus, and Achilles tendon. No significant differences in stiffness of all muscle tendons were identified between the early follicular and ovulatory phases. In the ovulatory phase, a significant positive correlation was seen between stiffness of RF and PT, and between stiffness of VM and PT. These results suggest that the stiffness of muscles and tendons of anterior sites of the thigh and posterior sites of the lower leg may not change between the early follicular and ovulatory phases. During the ovulatory phase, tendons may also be stiffer in individuals with stiffer anterior thigh muscles.
ARTICLE | doi:10.20944/preprints202301.0141.v1
Subject: Physical Sciences, Other Keywords: tibialis anterior tendon; attachment site area; three-dimensional; medial cuneiform bone; first metatarsal bone
Online: 9 January 2023 (06:36:49 CET)
The purpose of this study was to clarify the attachment types of the tibialis anterior tendon (TAT) in Japanese fixed cadavers and to determine the attachment site area in three dimensions. We examined 100 feet from 50 Japanese cadavers. The TAT was classified according to differences in the number of fiber bundles as: Type I, with one fiber bundle; Type II, with two fiber bundles; and Type III, with three fiber bundles. The attachment site area of the TAT was measured using a three-dimensional scanner. Cases were Type II in 95% and Type III in 5%, with no cases of Type I identified. In Type II, mean attachment site areas were 85.2 ± 18.2 mm2 for the medial cuneiform bone (MCB) and 72.4 ± 19.0 mm2 for the first metatarsal bone (1MB), showing a significantly larger area for MCB than for 1MB. These findings suggest the possibility of ethnic differences in TAT attachment types and suggest that TAT attachments in Japanese individuals are highly likely to be Type II, with rare cases of Type III. Accurate measurement of attachment site areas is possible with appropriate three-dimensional measurements.