A classification of the plantar intrinsic foot muscles based on the physiological cross-sectional area and muscle fiber length in healthy young adult males.

BACKGROUND: Plantar intrinsic foot muscles (PIFMs) are composed of 10 muscles and play an essential role in achieving functional diversity in the foot. Previous studies have identified that the morphological profiles of PIFMs vary between individuals. The morphological profiles of a muscle theoretically reflect its output potentials: the physiological cross-sectional area (PCSA) of a muscle is proportional to its maximum force generation, and the muscle fiber length (FL) is its shortening velocity. This implies that the PCSA and FL may be useful variables for characterizing the functional diversity of the individual PIFM. The purpose of this study was to examine how individual PIFMs can be classified based on their PCSA and FL. METHODS: In 26 healthy young adult males, the muscle volume and muscle length of seven PIFMs (abductor hallucis, ABDH; abductor digiti minimi, ABDM; adductor hallucis oblique head, ADDH-OH; ADDH transverse head, ADDH-TH; flexor digitorum brevis, FDB; flexor hallucis brevis, FHB; quadratus plantae, QP) were measured using magnetic resonance imaging. The PCSA and FL of each of the seven PIFMs were then estimated by combining the data measured from the participants and those of muscle architectural parameters documented from cadavers in previous studies. A total of 182 data samples (26 participants × 7 muscles) were classified into clusters using k-means cluster analysis. The optimal number of clusters was evaluated using the elbow method. RESULTS: The data samples of PIFMs were assigned to four clusters with different morphological profiles: ADDH-OH and FHB, characterised by large PCSA and short FL (high force generation and slow shortening velocity potentials); ABDM and FDB, moderate PCSA and moderate FL (moderate force generation and moderate shortening velocity potentials); QP, moderate PCSA and long FL (moderate force generation and rapid shortening velocity potentials); ADDH-TH, small PCSA and moderate FL (low force generation and moderate shortening velocity potentials). ABDH components were assigned equivalently to the first and second clusters. CONCLUSIONS: The approach adopted in this study may provide a novel perspective for interpreting the PIFMs' function based on their maximal force generation and shortening velocity potentials.

Vortex structure and fluid force changed by altering whole-body kinematic parameters during underwater undulatory swimming.

Swimmers generate vortices around their bodies during underwater undulatory swimming (UUS). Alteration of UUS movement would induce changes in vortex structure and fluid force. This study investigated whether a skilled swimmer's movement generated an effective vortex and fluid force for increasing the UUS velocity. A three-dimensional digital model and kinematic data yielded during UUS with maximum effort were collected for one skilled and one unskilled swimmer. The skilled swimmer's UUS kinematics were input into the skilled swimmer's model (SK-SM) and unskilled swimmer's model (SK-USM), followed by the kinematics of the unskilled swimmer (USK-USM and USK-SM, respectively). The vortex area, circulation, and peak drag force were determined using computational fluid dynamics. A larger vortex with greater circulation at the ventral side of the trunk and a greater circulation vortex behind the swimmer were observed in SK-USM compared to USK-USM. USK-SM generated a smaller vortex on the ventral side of the trunk and behind the swimmer, with a weaker circulation behind the swimmer compared to SK-SM. The peak drag force was larger for SK-USM than for USK-USM. Our results indicate that an effective vortex for propulsion was generated when a skilled swimmer's UUS kinematics was input in the other swimmer's model.

Quantification of Extramyocellular Lipids and Intramuscular Fat from Muscle Echo Intensity in Lower Limb Muscles: A Comparison of Four Ultrasound Devices against Magnetic Resonance Spectroscopy.

This study aimed to compare different ultrasound devices with magnetic resonance spectroscopy (MRS) to quantify muscle lipid content from echo intensity (EI). Four different ultrasound devices were used to measure muscle EI and subcutaneous fat thickness in four lower-limb muscles. Intramuscular fat (IMF), intramyocellular (IMCL) and extramyocellular lipids (EMCL) were measured using MRS. Linear regression was used to compare raw and subcutaneous fat thickness-corrected EI values to IMCL, EMCL and IMF. IMCL had a poor correlation with muscle EI (r = 0.17-0.32, NS), while EMCL (r = 0.41-0.84, p < 0.05-p < 0.001) and IMF (r = 0.49-0.84, p < 0.01-p < 0.001) had moderate to strong correlation with raw EI. All relationships were improved when considering the effect of subcutaneous fat thickness on muscle EI measurements. The slopes of the relationships were similar across devices, but there were some differences in the y-intercepts when raw EI values were used. These differences disappeared when subcutaneous fat thickness-corrected EI values were considered, allowing for the creation of generic prediction equations (r = 0.41-0.68, p < 0.001). These equations can be used to quantify IMF and EMCL within lower limb muscles from corrected-EI values in non-obese subjects, regardless of the ultrasound device used.

Interaction Between Sarcopenic Obesity and Nonlocomotive Physical Activity on the Risk of Depressive Symptoms in Community-Dwelling Older Adult Japanese Women.

This study aimed to investigate the interaction between sarcopenic obesity and locomotive and nonlocomotive physical activity (PA) on the risk of depressive symptoms in community-dwelling older Japanese women. Participants were 143 community-dwelling older women aged 64-94 years. PA was measured using a three-axis accelerometer. Participants were classified according to two levels of total, locomotive, and nonlocomotive PA. Depressive symptoms were assessed by a self-administered survey consisting of the 15-item Japanese version of the Geriatric Depression Scale (GDS-15-J). The interaction between sarcopenic obesity groups and total or locomotive PA did not affect GDS-15-J scores. However, the interaction between sarcopenic obesity groups and nonlocomotive PA significantly affected GDS-15-J scores (p < .05). Moreover, sarcopenic obesity in the low PA group had significantly higher GDS-15-J scores compared with sarcopenic obesity in the high PA group (p < .05). We concluded that sarcopenic obesity combined with low nonlocomotive PA may exacerbate depressive symptoms in older women.

Point Prevalence of the Biomechanical Dimension of Dysfunctional Breathing Patterns Among Competitive Athletes.

ABSTRACT: Shimozawa, Y, Kurihara, T, Kusagawa, Y, Hori, M, Numasawa, S, Sugiyama, T, Tanaka, T, Suga, T, Terada, RS, Isaka, T, and Terada, M. Point prevalence of the biomechanical dimension of dysfunctional breathing patterns among competitive athletes. J Strength Cond Res 37(2): 270-276, 2023-There is growing evidence of associations between altered biomechanical breathing patterns and numerous musculoskeletal and psychological conditions. The prevalence of dysfunctional and diaphragmatic breathing patterns is unknown among athletic populations. The purpose of this study was to examine the prevalence of dysfunctional and diaphragmatic breathing patterns among athletic populations with a clinical measure to assess the biomechanical dimension of breathing patterns. Using a cross-sectional design, 1,933 athletes across multiple sports and ages were screened from 2017 to 2020. Breathing patterns were assessed using the Hi-Lo test in the standing position. Scores of the Hi-Lo test were determined based on the presence or absence of abdominal excursion, anterior-posterior chest expansion, superior rib cage migration, and shoulder elevation. The Hi-Lo test scores were used to categorize observational breathing mechanics as dysfunctional and diaphragmatic breathing patterns. The prevalence of athletes with dysfunctional breathing patterns was 90.6% (1,751 of 1,933). Athletes with diaphragmatic breathing patterns accounted for 9.4% of all athletes in our sample (182 of 1,933). There were no differences in the proportion of breathing patterns between male and female athletes ( p = 0.424). Breathing patterns observations were associated with sport-setting categories ( p = 0.002). The highest percentages of dysfunctional breathers were in middle school student athletes (93.7%), followed by elementary school student athletes (91.2%), high school student athletes (90.6%), professional/semiprofessional athletes (87.5%), and collegiate athletes (84.8%). The current study observed that dysfunctional breathing patterns (90.6%) in the biomechanical dimension were more prevalent than diaphragmatic breathing pattern (9.4%) among competitive athletes. These results suggest that clinicians may need to consider screening breathing patterns and implementing intervention programs aimed to improve the efficiency of biomechanical dimensions of breathing patterns in athletic populations. This study may help raise awareness of impacts of dysfunctional breathing patterns on athletes' health and performance.

Contributions of flexor hallucis longus and brevis muscles to isometric toe flexor force production.

PURPOSE: Morphological differences between the two primary great toe flexors - flexor hallucis longus (FHL) and flexor hallucis brevis (FHB) - likely drive differences in how these muscles contribute to functional toe flexor torque production. The aim of the study was to investigate FHL and FHB activation in two isometric toe flexion tasks - one called a "toe-pushing" task with the metatarsophalangeal (MTP) joints dorsiflexed and the interphalangeal (IP) joints in neutral and another called a "toe-gripping" task with the MTP joints in neutral and flexed IP joints. METHODS: Twenty participants' FHL and FHB muscles were instrumented with intramuscular electromyography electrodes. Muscle activation was normalized to a maximum voluntary contraction and compared between the two isometric toe flexor force production tasks. RESULTS: Overall, participants utilized these two toe flexors completely differently in the two tasks. In the toe-gripping task, the FHL was activated to a much greater extent than the FHB. In fact, 18 our of 20 participants activated FHL at more than 70% maximum voluntary contraction and half of participants activated FHB at less than 10%. In contrast, muscle activation during the toe-pushing task appeared more reliant on the FHB for most participants. CONCLUSIONS: Different contributions from the FHL and FHB to toe flexor force production in these two tasks are potentially driven by differences in muscle functional length among other factors. These findings help to inform the selection of rehabilitation and training exercises meant to preferentially target intrinsic or extrinsic foot musculature.

The Large and Strong Vortex Around the Trunk and Behind the Swimmer is Associated with Great Performance in Underwater Undulatory Swimming.

Swimmers can produce horizontal body velocity by generating and shedding vortices around their body during underwater undulatory swimming (UUS). It has been hypothesized that the horizontal shedding velocity, area and circulation of the vortex around the swimmer's body are associated with UUS performance. The purpose of this study was to investigate whether the shedding velocity, area and circulation of vortices around swimmers' bodies are correlated with the horizontal body velocity during UUS. Computational fluid dynamics (CFD) was conducted to obtain the vortex structure during UUS in nine male swimmers. Morphological and kinematic data of each subject were obtained and used to reconstruct the UUS movement on CFD. The horizontal velocity of the center of vorticity, the area and circulation of vortices around the ventral side of the trunk, dorsal side of shoulder and waist, and behind the swimmer were determined from the simulation results. Positive correlations were found between the vortex area and circulation around the ventral side of the trunk (area r = 0.938, p < 0.05; circulation r = 0.915, p < 0.05) and behind the swimmer (area r = 0.738, p < 0.05; circulation r = -0.680, p < 0.05), and the horizontal body velocity. The horizontal shedding velocity of the center of vorticity of the vortices around the swimmer's body was not significantly correlated with the horizontal body velocity. These results suggest that the generation of a large and strong vortex around the trunk and behind the swimmer is associated with great UUS performance.

Associations of muscle volume of individual human plantar intrinsic foot muscles with morphological profiles of the foot.

Human plantar intrinsic foot muscles consist of 10 muscles that originate and insert within the sole of the foot. It is known that the anatomical cross-sectional area (ACSA) and muscle thickness of two plantar intrinsic foot muscles, the flexor hallucis brevis (FHB) and abductor hallucis (ABH), associate with morphological parameters of the foot, such as total and truncated foot length and navicular height. However, it is unclear how the size for each of the plantar intrinsic foot muscles associates with various morphological profiles of the foot. This study aimed to elucidate this subject. By using magnetic resonance imaging (MRI), serial images of the right foot were obtained in 13 young adult men without foot deformities. From the obtained MR images, ACSA for each of the individual plantar intrinsic foot muscles was analyzed along the foot length, and then its muscle volume (MV) was calculated. The analyzed muscles were the abductor digiti minimi (ABDM), ABH, adductor hallucis oblique head (ADDH-OH), adductor hallucis transverse head (ADDH-TH), flexor digitorum brevis (FDB), FHB, and quadratus plantae (QP). Furthermore, MV of the whole plantar intrinsic foot muscle (WHOLE) was defined as the total MVs of all the analyzed muscles. As morphological parameters, total foot length, truncated foot length, forefoot width, ball circumference, instep circumference, navicular height, great toe eversion angle, and little toe inversion angle were measured using a laser three-dimensional foot scanner in standing and sitting conditions. In addition, navicular drop (ND) and normalized truncated navicular height (NTNH) were also calculated as medial longitudinal arch (MLA) height indices. The MV of WHOLE was significantly associated with the forefoot width, ball circumference, and instep circumference (r = 0.647-0.711, p = 0.006-0.013). Positive correlations were found between the forefoot width and MV of FHB, FDB, and QP (r = 0.564-0.653, p = 0.015-0.045), between the ball circumference and MV of QP (r = 0.559, p = 0.047), between the instep circumference and MV of FHB (r = 0.609, p = 0.027), and between the little toe inversion angle and MV of QP (r = 0.570, p = 0.042). The MVs of ABH, ABDM, and ADDH-OH were not significantly correlated with any morphological parameters of the foot. Similarly, no significant correlations were found between MV of each muscle and either of the MLA height indices (ND and NTNH). Thus, the current results indicate that forefoot width and circumferential parameters (instep and ball circumference), not MLA height, associate with the size of the whole plantar intrinsic foot muscles, especially those specialized in toe flexion (FHB, FDB, and QP).

Contributions of Intrinsic and Extrinsic Foot Muscles during Functional Standing Postures.

Purpose: Maintaining balance during static standing postures requires the coordination of many neuromuscular mechanisms. The role of the intrinsic and extrinsic foot muscles in this paradigm has yet to be clearly defined. The purpose of this study was to explore foot muscle activation during static phases on common weight-bearing tasks of varying loads and balance demands. Methods: Twenty healthy young adults performed 6 standing postures (single-limb and double-limb stand, squat, and heel raise) with one foot on a force plate. Muscle activity was recorded from the abductor hallucis, flexor hallucis longus and brevis, and tibialis posterior using intramuscular electrodes; surface electrodes were used to record activity from the peroneus longus and tibialis anterior. Two-way repeated measures ANOVA (2 loading conditions × 3 postures) were run to compare muscle activation and center of pressure velocity. Results: Intrinsic foot muscle activity increased as loading and postural demand increased; however, the specific effects varied for each of the extrinsic foot muscles. Conclusions: These results suggest that the intrinsic foot muscles play an important role in maintaining static balance. Strengthening intrinsic and extrinsic foot muscles may help increase stability in people who have weak toe flexors or who suffer from a variety of foot pathologies.

Associations between the size of individual plantar intrinsic and extrinsic foot muscles and toe flexor strength.

BACKGROUND: The size of the plantar intrinsic and extrinsic foot muscles has been shown to be associated with toe flexor strength (TFS). Previous studies adopted the size of limited plantar intrinsic foot muscles or a compartment containing several muscles as an independent variable for TFS. Among the plantar intrinsic and extrinsic foot muscles, therefore, it is unclear which muscle(s) primarily contributes to TFS production. The present study aimed to clarify this subject. METHODS: In 17 young adult men, a series of anatomical cross-sectional area of individual plantar intrinsic and extrinsic foot muscles was obtained along the foot length and the lower leg length, respectively, using magnetic resonance imaging. Maximal anatomical cross-sectional area (ACSAmax) and muscle volume (MV) for each constituent muscle of the plantar intrinsic foot muscles (flexor hallucis brevis; flexor digitorum brevis, FDB; abductor hallucis; adductor hallucis oblique head, ADDH-OH; adductor hallucis transverse head, ADDH-TH; abductor digiti minimi; quadratus plantae) and extrinsic foot muscles (flexor hallucis longus; flexor digitorum longus) were measured. TFS was measured with a toe grip dynamometry. RESULTS: TFS was significantly associated with the ACSAmax for each of the ADDH-OH (r = 0.674, p = 0.003), ADDH-TH (r = 0.523, p = 0.031), and FDB (r = 0.492, p = 0.045), and the MV of the ADDH-OH (r = 0.582, p = 0.014). As for the ADDH-OH, the correlation coefficient with TFS was not statistically different between ACSAmax and MV (p = 0.189). Stepwise multiple linear regression analysis indicated that ACSAmax and MV of the ADDH-OH alone explained 42 and 29%, respectively, of the variance in TFS. CONCLUSION: The ADDH-OH is the primary contributor to TFS production among the plantar intrinsic and extrinsic foot muscles as the result of the stepwise multiple linear regression analysis.

Effects of age and sex on association between toe muscular strength and vertical jump performance in adolescent populations.

Toe muscular strength plays an important role in enhancing athletic performance because the forefoot is the only part of the body touching the ground. In general, muscular strength increases with age throughout adolescence, and sex-related difference in muscular strength becomes evident during childhood and adolescence. However, toe muscular strength is known to be levelled off after late adolescence in both sexes. For adolescent populations, therefore, the association of toe muscular strength with physical performance might differ with age and/or sex. This study aimed to investigate differences in relationships between toe muscular strength and vertical jump performance across sex and age in adolescent populations. The maximum isometric strength of the toe muscles and vertical jump height (VJ) were assessed in 479 junior high school students (JH) aged 12-14 years (243 boys and 236 girls) and 465 high school students (HS) aged 15-18 years (265 boys and 200 girls). Two types of measurements were performed to evaluate the toe muscular strength: toe gripping strength (TGS) with the metatarsophalangeal joint in the plantar flexed position and toe push strength (TPS) with the metatarsophalangeal joint in the dorsiflexed position. TGS and TPS were normalized to body weight. Two-way ANOVA showed that TGS had significant main effects of sex (boys > girls) and age (HS > JH) while TPS only had a significant main effect of sex (boys > girls). When the effects of sex and age were separately analyzed, VJ was significantly correlated with TGS in JH girls, HS girls, and JH boys (r = 0.253-0.269, p < 0.05), but not in HS boys (r = 0.062, p = 0.3351). These results suggest that toe muscular strength is relatively weakly associated with vertical jump performance in adolescent boys and girls, but the association would not be established in high school boys.

Associations between locomotive and non-locomotive physical activity and physical performance in older community-dwelling females with and without locomotive syndrome: a cross-sectional study.

BACKGROUND: Locomotive syndrome (LS) is a condition of reduced mobility due to a disorder of the locomotive system. Increasing moderate to vigorous physical activity (MVPA) has been recommended to prevent LS. However, to increase daily MVPA is difficult for older people with LS. The MVPA consists of not only locomotive activities such as walking but also non-locomotive activities such as household activities. The aim of this study was to examine the associations between locomotive/non-locomotive MVPA and physical performance in older females with and without LS. METHODS: Participants of this cross-sectional study were 143 older community-dwelling Japanese females. The participants were divided into two groups based on the results of the stand-up test: the normal group (NL) (n = 86) and the LS group (n = 57). Both the locomotive and non-locomotive PA seperately measured with its intensity. The intensity of physical activity (PA) was calculated as METs and classified as sedentary behavior (SB 1-1.5 metabolic equivalent tasks (METs)), low-intensity physical activity (LPA 1.6-2.9 METs), and MVPA (≥ 3 METs). For example, locomotive LPA is slow walking speed of 54 m/min, and locomotive MVPA is walking speed of 67 m/min. While non-locomotive LPA is office work and cooking, non-locomotive MVPA is housecleaning. Physical function was evaluated by handgrip strength, walking speed, and 2-step test. RESULTS: Walking speed, hand-grip strength, 2-step test, daily step counts, and all PA measurements were not significantly different between two groups. In the LS, locomotive MVPA (r = 0.293, p < 0.05) and total MVPA (r = 0.299, p < 0.05) was significantly correlated with walking speed, but not in the NL. CONCLUSIONS: Walking speed was positively correlated with locomotive MVPA and total MVPA in the LS group, but not in NL group. This result suggests that slow walking speed in older people with LS occur in connection with lower locomotive MVPA and total MVPA.

Change of Direction Speed Tests in Basketball Players: A Brief Review of Test Varieties and Recent Trends.

Change of direction speed (CODS) is essential for basketball performance, extensively assessed by various tests. This review aimed to summarize the CODS test varieties for basketball players on publications until 2019 and identify recent trends regarding what types of tests have gained attention in the 2010s. Electronic literature searches were conducted using three databases with relevant keywords. 104 studies were found eligible, conducting CODS tests 159 times in total with 48 test varieties. To facilitate distinctions between the tests, each test was categorized into one of three types based on the distinctive movement characteristics and changing angles as follows: Defensive (involving lateral shuffling), 180°-turn (exerting only 180°-turns), and Cutting (performing diagonal- or side-cut). We then counted the number of publications and adopted times reported per year for each test, and calculated the adoption rate for each categorized test type. The first CODS test performed in basketball players was the T-Test, reported in 1991, and this was the most commonly adopted test (44/159 times). The 2010s saw abrupt increases in the number of publications (1990s-2000s-2010s: 5-9-90) and test varieties (4-7-44). The adoption rates in the 2010s were similar among the three types (i.e., Defensive/180°-turn/Cutting: 37%/30%/33%), with the Cutting type gradually increasing over the last three decades (1990s-2000s-2010s: 0%-9%-33%). These results suggest that while CODS performances in basketball players are increasingly studied with various tests, recent studies give equal weight to all of the three categorized test types, with increasing adoption of the Cutting type, to assess specific CODS performances.

Toe flexor strength is associated with mobility in older adults with pronated and supinated feet but not with neutral feet.

BACKGROUND: Older adults are known to have more pronated foot posture and decreased toe flexor strength (TFS), as well as decreased mobility in daily life compared to young adults. Although foot posture is reported to be an influential factor for walking biomechanics in young adults, there is less information on this subject in older adults. Age-related reduction in TFS is shown to be associated with impairments of functional performance, but it is poorly understood whether foot posture influences the relationships between TFS and functional performances. Therefore, the present study aimed to elucidate this concern by examining older women. METHODS: Seventy community-dwelling older women (76.8 ± 4.4 years) voluntarily participated in this study. Foot posture was evaluated by the 6-item foot posture index (FPI). Based on the FPI score, participants were allocated to pronated, neutral, or supinated group (n = 33, 26, and 11, respectively). TFS was assessed using a toe grip dynamometer in a seated position. Scores of 30-s chair stand, timed up-and-go, 5-m comfortable-speed walking, and static balance tests were determined to evaluate functional performances. Pearson's correlation coefficients were computed to examine the relationships between TFS and functional performances in each group. RESULTS: TFS positively correlated with comfortable walking speed in the pronated (r = 0.37, p = 0.03) and supinated (r = 0.76, p < 0.001) groups, but not in the neutral group (r = 0.17, p = 0.42). For the two significant relationships, an analysis of covariance showed that there was no significant difference between the pronated and supinated groups in the slopes of the regression lines, suggesting a similar relative contribution of TFS to comfortable walking speed between the two groups. In addition, TFS tended to negatively correlate with timed up-and-go time in the pronated (r = - 0.32, p = 0.07) and supinated (r = - 0.56, p = 0.08) groups, and positively correlate with 30-s chair stand score in the pronated group (r = 0.31, p = 0.08). CONCLUSIONS: The present study indicates that TFS would be associated with mobility, walking performance in particular, in older women with pronated and supinated feet but not with neutral feet.

Decreased Muscle Strength of Knee Flexors is Associated with Impaired Muscle Insulin Sensitivity in Non-Diabetic Middle-Aged Japanese Male Subjects.

INTRODUCTION: Reduced muscle strength is a high risk factor for type 2 diabetes mellitus, and this association is especially strong in non-obese male individuals. However, it remains unclear how reduced muscle strength affects susceptibility to diabetes. We have examined whether lower limb muscle strength is associated with insulin resistance in non-obese Japanese male subjects. METHODS: Measurements from 64 non-diabetic, non-obese, middle-aged Japanese men were analyzed. Insulin sensitivity in muscle was measured using the hyperinsulinemic-euglycemic clamp. Isometric muscle strength of the knee extensor and flexor muscles was evaluated using a dynameter. RESULTS: Lower muscle strength of knee flexors, but not knee extensors, was associated with impaired muscle insulin sensitivity (knee flexor muscles: low, medium, and high strength was 6.6 ± 2.2, 7.3 ± 2.0, and 8.8 ± 2.2 mg/kg per minute, respectively, p for trend < 0.05; knee extensor muscles: low, medium, and high strength was 7.3 ± 2.5, 7.5 ± 2.2, and 7.8 ± 2.3 mg/kg per minute, respectively, p for trend = 0.73). Knee flexor muscle strength was also identified as an independent determinant of insulin sensitivity in the multiple regression analysis (ß = 0.274, p = 0.036). CONCLUSIONS: Diminished strength of knee flexor muscles, but not knee extensor muscles, was associated with muscle insulin sensitivity in non-diabetic, non-obese Japanese male subjects.

Lycopene-Family Carotenoids Confer Thermostability on Photocomplexes from a New Thermophilic Purple Bacterium.

Blastochloris tepida is a newly described thermophilic purple bacterium containing bacteriochlorophyll b. Using purified light-harvesting 1 reaction center (LH1-RC) core complexes from Blc. tepida, we compared the biochemical, spectroscopic, and thermal denaturation properties of these complexes with those of its mesophilic counterpart, Blc. viridis. Besides their growth temperature optima, a striking difference between the two species was seen in the carotenoid composition of their LH1-RC complexes. The more thermostable Blc. tepida complex contained more carotenoids with longer conjugation lengths (n > 9), such as lycopenes (n = 11), and had a total carotenoid content significantly higher than that of the Blc. viridis complex, irrespective of the light intensity used for growth. The thermostability of LH1-RCs from both Blc. tepida and Blc. viridis decreased significantly in cells grown in the presence of diphenylamine, a compound that inhibits the formation of highly conjugated carotenoids. In contrast to the thermophilic purple bacterium Thermochromatium tepidum, where Ca2+ is essential for LH1-RC thermostability, Ca2+ neither was present in nor had any effect on the thermostability of the Blc. tepida LH1-RC. These results point to a mechanism that carotenoids with elongated conjugations enhance hydrophobic interactions with proteins in the Blc. tepida LH1-RC, thereby allowing the complexes to withstand thermal denaturation. This conclusion is bolstered by a structural model of the Blc. tepida LH1-RC and is the first example of photocomplex thermostability being linked to a carotenoid-based mechanism.

Adverse effects of the coexistence of locomotive syndrome and sarcopenia on the walking ability and performance of activities of daily living in Japanese elderly females: a cross-sectional study.

[Purpose] The aim of this study was to investigate whether the coexistence of locomotive syndrome and sarcopenia is associated with the risk of fall or performance of activities of daily living in elderly females. [Participants and Methods] We categorized 112 Japanese elderly female participants under three groups: control, locomotive syndrome, and locomotive syndrome and co-existing sarcopenia. We compared the groups based on the mean scores of anthropometric and physical function measurements, the Timed Up and Go test, and the Tokyo Metropolitan Institute of Gerontology Index of Competence to evaluate activities of daily living. [Results] The Timed Up and Go test score significantly differed among the groups. The score of the Timed Up and Go test significantly correlated with scores of the skeletal muscle mass index, skeletal muscle strength grading, and usual gait speed. The total score of the Tokyo Metropolitan Institute of Gerontology Index of Competence significantly decreased in all the groups. [Conclusion] The coexistence of locomotive syndrome and sarcopenia is associated with an increased risk of fall and worsened performance of activities of daily living. Further, the risk of fall is associated with the skeletal muscle mass, skeletal muscle strength, and gait speed. It seems likely that, compared to sarcopenia, locomotive syndrome is more sensitive to lower limb dysfunctions.

Associations among Bone Mineral Density, Physical Activity and Nutritional Intake in Middle-Aged Women with High Levels of Arterial Stiffness: A Pilot Study.

There is little consensus regarding the impacts of physical activity and nutrient intake on bone mineral density (BMD) in subjects with high or low levels of arterial stiffness. This study was performed to investigate whether physical activity and nutrient intake are associated with BMD in middle-aged women with high levels of arterial stiffness. The study population consisted of middle-aged women aged 40-64 years (n = 22). BMD was assessed by dual-energy X-ray absorptiometry. Carotid-femoral pulse wave velocity (cf-PWV) was used as an indicator of arterial stiffness. Subjects were divided into two groups by median cf-PWV. Physical activity in free-living conditions was evaluated using a triaxial accelerometer. Nutrient intake was also measured using the brief-type self-administered diet history questionnaire. In the High-PWV group, BMD showed a significant negative correlation with age. Using a partial correlation model, BMD was associated with the number of steps and unsaturated fatty acid intake in the High-PWV group. These results suggest that BMD in middle-aged women with high levels of arterial stiffness may be associated with both the number of steps and nutritional intake. Recommendations of physical activity and nutritional intake for the prevention of osteopenia should include consideration of arterial stiffness.

Relationship between Trunk Muscularity and Club Head Speed in Male Golfers.

This study examined how the volume of trunk muscles and its bilateral asymmetry are related to club head speed in golfers. Fourteen right-handed male golfers performed five driver shots, and the club head speed for each trial was calculated from a three-dimensional reflective marker position of the club head immediately before impact. The volume of each side of the rectus abdominis, erector spinae, psoas major, quadratus lumborum, lateral abdominal wall muscle, and multifidus was determined using magnetic resonance imaging. For each muscle, the ratio of the larger to smaller side in muscle volume was calculated to assess bilateral asymmetry. The club head speed correlated positively with the volume of each side of the rectus abdominis and erector spinae, left quadratus lumborum, and the asymmetric ratio of the psoas major (r=0.595-0.747), but negatively with the asymmetric ratio of the quadratus lumborum (r=-0.641). Multiple regression analysis revealed that the right erector spinae volume and the asymmetric ratio of the psoas major were significant contributors for the club head speed (R2=0.797). These results indicate that the variation in the club head speed can be strongly explained by the absolute volume and bilateral asymmetry of specific trunk muscles.

Effect of a task's postural demands on medial longitudinal arch deformation and activation of foot intrinsic and extrinsic musculatur.

PURPOSE: It is not well established how motion and muscle activation of the medial longitudinal arch (MLA) of the foot vary under different loading conditions. Intrinsic and extrinsic foot muscles may play a role in postural control, which may be investigated by comparing loading tasks with differing postural demands. The objective of this study was to investigate the interaction of MLA flexibility and loading task on muscle activation. METHODS: Twenty healthy adults completed two instrumented single-foot loading tasks: controlled external load of 50% body weight while sitting and bilateral standing. Fine-wire intramuscular and surface electromyography collected flexor hallucis brevis, abductor hallucis, tibialis posterior, flexor hallucis longus, tibialis anterior, and peroneus longus activation. MLA deformation was measured as a percent change in navicular height with loading. RESULTS: During seated external loading, greater MLA deformation was associated with greater muscle activation for all instrumented muscles (R² = 0.224-0.303, p < 0.05) except for tibialis anterior. During bilateral stance, there were no correlations between MLA deformation and muscle activation. Activation of all extrinsic muscles except for tibialis anterior were greater during bilateral standing than during external loading ( p = 0.002-0.013), indicating activation of these muscles was caused by postural demands of the standing task, not simply load. CONCLUSIONS: MLA deformation and muscle activation are strongly task-dependent.