Inhibitory SMAD6 interferes with BMP-dependent generation of muscle progenitor cells and perturbs proximodistal pattern of murine limb muscles.

The mechanism of pattern formation during limb muscle development remains poorly understood. The canonical view holds that naïve limb muscle progenitor cells (MPCs) invade a pre-established pattern of muscle connective tissue, thereby forming individual muscles. Here, we show that early murine embryonic limb MPCs highly accumulate pSMAD1/5/9, demonstrating active signaling of bone morphogenetic proteins (BMP) in these cells. Overexpression of inhibitory human SMAD6 (huSMAD6) in limb MPCs abrogated BMP signaling, impaired their migration and proliferation, and accelerated myogenic lineage progression. Fewer primary myofibers developed, causing an aberrant proximodistal muscle pattern. Patterning was not disturbed when huSMAD6 was overexpressed in differentiated muscle, implying that the proximodistal muscle pattern depends on BMP-mediated expansion of MPCs before their differentiation. We show that limb MPCs differentially express Hox genes, and Hox-expressing MPCs displayed active BMP signaling. huSMAD6 overexpression caused loss of HOXA11 in early limb MPCs. In conclusion, our data show that BMP signaling controls expansion of embryonic limb MPCs as a prerequisite for establishing the proximodistal muscle pattern, a process that involves expression of Hox genes.

An in-person survey of the influence of the COVID-19 pandemic on physical function, functional capacity, cognitive function, and mental health among community-dwelling older adults in Japan from 2016 to 2022.

BACKGROUND: The COVID-19 outbreak might have had several effects on older adults; however, much of the previous research only included self-report, cross-sectional, and online-survey data in the early stage of the pandemic. We conducted a face-to-face survey before and after the COVID-19 pandemic and investigated the influence of the pandemic on several functions to distinguish between changes due to aging and changes due to the pandemic using a linear mixed model. METHODS: A total of 8 longitudinal surveys were conducted from 2016 to 2022. Physical function was assessed by weight, body mass index, body fat percentage, skeletal muscle mass index, calf circumference, grip strength, knee extension strength, the 5-times chair stand test, the timed up & go test and 5-m walking test. Functional capacity was measured using the Tokyo Metropolitan Institute of Gerontology index of competence, cognitive function was measured using the Trail Making Test - A, and mental health was measured using the Geriatric Depression Scale. RESULTS: Of a total of 73 participants, 51 (69.9%) were female. The mean age at first participation was 71.82 years (SD = 4.64). The results of the linear mixed model showed that lower-limb muscle strength and body fat percentage and cognitive function changed significantly before and after the pandemic, while grip strength, functional capacity, and mental health did not. CONCLUSIONS: The changes in these functions between before and after the pandemic might be attributed to the diminished opportunities for the independent older individuals to go out and engage in activities. Although functional capacity did not change, lower-limb muscle strength is important for functional independence. This decline might influence the functional capacity of these individuals in the future.

Ex vivo adult stem cell characterization from multiple muscles in ambulatory children with cerebral palsy during early development of contractures.

Cerebral palsy (CP) is one of the most common conditions leading to lifelong childhood physical disability. Literature reported previously altered muscle properties such as lower number of satellite cells (SCs), with altered fusion capacity. However, these observations highly vary among studies, possibly due to heterogeneity in patient population, lack of appropriate control data, methodology and different assessed muscle. In this study we aimed to strengthen previous observations and to understand the heterogeneity of CP muscle pathology. Myogenic differentiation of SCs from the Medial Gastrocnemius (MG) muscle of patients with CP (n = 16, 3-9 years old) showed higher fusion capacity compared to age-matched typically developing children (TD, n = 13). Furthermore, we uniquely assessed cells of two different lower limb muscles and showed a decreased myogenic potency in cells from the Semitendinosus (ST) compared to the MG (TD: n = 3, CP: n = 6). Longitudinal assessments, one year after the first botulinum toxin treatment, showed slightly reduced SC representations and lower fusion capacity (n = 4). Finally, we proved the robustness of our data, by assessing in parallel the myogenic capacity of two samples from the same TD muscle. In conclusion, these data confirmed previous findings of increased SC fusion capacity from MG muscle of young patients with CP compared to age-matched TD. Further elaboration is reported on potential factors contributing to heterogeneity, such as assessed muscle, CP progression and reliability of primary outcome parameters.

Assessing the Post-Activation Performance Enhancement of Upper Limbs in Basketball Athletes: A Sensor-Based Study of Rapid Stretch Compound and Blood Flow Restriction Training.

OBJECTIVE: This study introduces a novel methodology combining rapid stretch compound training with blood flow restriction (BFR) to investigate post activation performance enhancement (PAPE) in basketball players, a field that has been predominantly explored for lower limbs. We aimed to assess the efficacy of this combined approach on upper limb muscle performance in athletes. METHODS: We employed a randomized, self-controlled crossover trial with ten male basketball players. The bench press throw (BPT) served as the primary metric, with players undergoing four interventions post-baseline: (1) STR-plyometric training; (2) BFR-blood flow restriction; (3) COMB-STR integrated with BFR; and (4) CON-control. Innovatively, we utilized an intelligent tracking sensor to precisely measure peak power (PP), peak velocity (PV), mean power (MP), and mean velocity (MV) at 4, 8, and 12 min post-intervention, providing a detailed temporal analysis of PAPE. RESULTS: The COMB intervention demonstrated superior PAPE effects at 4 min, significantly outperforming STR and BFR alone and the control group across all measured indices (p < 0.05). Notably, the COMB group maintained these improvements for PV, PP, and H up to 12 min post-intervention, suggesting a prolonged effect. CONCLUSION: (1) The COMB stimulation has been shown to successfully induce PAPE more effectively than STR and BFR modality alone. (2) It appears that the optimal effects of PAPE are achieved within 4 min of exercising under this COMB. By the 12 min mark, only the COMB group continued to show significant improvements in PV, PP, and H compared to both the baseline and the CON group, while the effects in the STR and BFR groups further diminished. This suggests that although the PAPE effect is maintained over time, its optimal performance may peak at the 4 min mark and then gradually weaken as time progresses.

Association between upper limb muscle quality and knee osteoarthritis in dynapenia: an observational cross-sectional study.

Neurological and skeletal muscle properties are suggested causes of dynapenia. This study aimed to evaluate the relationship between upper limb muscle quality (grip strength/upper extremity muscle mass) and knee osteoarthritis in dynapenia, and to identify dynapenia-associated factors. Elderly individuals who responded to a public call for screening in Wakasa Town, Fukui Prefecture between June 2019 and November 2021 were included. The analysis included 433 participants (304 women aged 76.0 ±â€…7.1 years). Examination comprised (consecutively) a basic interview, physical function measurement, body composition measurement, and explanation of results. Dynapenia was observed in 67 patients. Binomial logistic regression analysis revealed that age, upper limb muscle quality score, and knee osteoarthritis were independent factors for dynapenia. Receiver operating characteristic analysis of the relationship between dynapenia and upper limb muscle quality showed an area under the curve of 0.806 (95% confidence interval: 0.658-0.953) for men (cut-off value, 14.3 kg/kg) and 0.849 for women (95% confidence interval: 0.858-0.968; cut-off value, 14.0 kg/kg). In conclusion, age, upper limb muscle quality, and knee osteoarthritis were independent factors of dynapenia. We demonstrated that upper limb muscle quality has good accuracy in detecting dynapenia in both men and women.

Weakness of lower limb muscle in symptomatic peripheral artery disease with media sclerosis detected by ultrasound shear wave elastography.

Background: Symptomatic peripheral arterial disease (PAD) is difficult to non-invasively diagnose in the presence of calcified, media sclerotic arteries that are incompressible by blood pressure cuffs. Standard ankle-brachial index (ABI) measurements in these PAD patients are very often not helpful. Shear wave elastography (SWE) is a modern ultrasound technique to detect peripheral muscle stiffness changes i.e. muscle weakness during exercise. In a pilot study, we examined whether SWE could be a reproducible tool for diagnosing ischemic loss of muscle stiffness in patients with PAD and concomitant arterial media sclerosis. Patients and methods: N=13 consecutive patients with peripheral artery disease and media sclerosis were enrolled in the pilot study. All 13 patients were symptomatic in different stages of their PAD due to hemodynamically relevant arterial stenosis or occlusions of limb arteries as confirmed by oscillography, color-coded duplex sonography or angiography. Results: ABI measurements were invalid in all 13 patients. Mean SWE measurements of medial gastrocnemius muscles showed a significant transient muscle stiffness loss (weakness) at maximum exercise (active dorsal flexion of the foot, 103.4±25.9 kPa on the asymptomatic vs. 62.5±21.9 kPa on the symptomatic limb (p<0.001). Conclusions: SWE can reproducibly detect peripheral muscle weakness during exercise in the symptomatic leg of media sclerotic PAD patients. SWE of lower limb muscles may help to identify symptomatic PAD in patients presenting with invalid ABI measurements and unclear vascular status.

Bone mineral density, limb muscle mass, muscle strength, and exercise capacity are reduced in female patients with distal radius fractures when the unaffected side grip strength is less than 18 kg.

BACKGROUND: Prevention of domino effects after distal radius fractures is important for improving life expectancy. Fragility fractures secondary to falls are associated with decreased bone mineral density, muscle strength, and exercise capacity. Grip strength is one of the simplest and most useful tests to comprehensively judge muscle strength. The purpose of this study was to examine whether grip strength is associated with bone mineral density, limb muscle mass, muscle strength, and exercise capacity, by comparing patient backgrounds based on the presence or absence of grip weakness in female patients with distal radius fractures. METHODS: This study included women with distal radius fractures who visited our orthopedics outpatient department between April 2015 and April 2020. Bone mineral density, limb muscle mass, skeletal muscle mass index, muscle strength (grip strength on unaffected side and quadriceps muscle strength), the Timed Up and Go test, and the Two-Step test were evaluated six to eight weeks after injury. Patients were divided into two groups according to the cutoff value of grip strength (18-21 kg), and 90 age-adjusted and matched participants were compared and examined. RESULTS: At the cutoff value of 18 kg, a significant decrease in lumbar spine and total proximal femur bone mineral density (p < 0.05, p < 0.05), limb muscle mass and skeletal muscle mass index (p < 0.01, p < 0.05), quadriceps femoris muscle strength (p < 0.01), the Timed Up and Go test (p < 0.05), and the Two-Step test (p < 0.01), was observed in the grip-weakness group compared to that in the no-grip-weakness group. CONCLUSIONS: In women with distal radius fracture and grip strength <18 kg on the unaffected side, bone mineral density, limb muscle mass, quadriceps femoris strength, and exercise capacity may be reduced. These results suggest reduced grip strength may be an indicator for further testing to prevent domino effects.

Influencing factors for the decline of limb muscle strength and the association with all-cause mortality: evidence from a nationwide population-based cohort study.

BACKGROUND: The decline of muscle strength, a typical characteristic of sarcopenia, greatly affects aging-related health outcomes; however, prospective data on influencing factors and mortality in the Chinese population are relatively sparse. AIMS: We investigated the influencing factors for the declined limb muscle strength and the association with all-cause mortality among the elderly Chinese individuals aged ≥ 65 years in a large long-term prospective cohort study. METHODS: We used data from the China Health and Retirement Longitudinal Study (CHARLS). Logistic regression analyses were performed to investigate the influencing factors of declined limb muscle strength. Cox proportional hazard models were used to analyze the impact on all-cause mortality, whose performance was evaluated by train-test cross-validation. RESULTS: The prevalences of declined upper and lower limb strength, which were defined by low hand grip strength (HS) and gait speed (GS), respectively, were 34.4% and 59.7%. The declined HS was significantly associated with older age (p < 0.001), female (p < 0.001), lower educational level (p < 0.001), lower BMI (p < 0.001), and combined with chronic diseases (p = 0.001). Moreover, the declined limb muscle strength was correlated with all-cause mortality (HR: 1.13, 95% CI 1.03-1.21 for HS; HR: 1.09, 95% CI 1.04-1.15 for GS), according to a multi-adjusted model with moderate predictive ability (C-index: 0.714, AUC of 7 year follow-up: 0.716). CONCLUSIONS: The decline of limb muscle strength was prevalent among elderly Chinese individuals and had a strong impact on all-cause mortality. Identification of key populations and tailored interventions on their influencing factors should be implemented in further research.

The effect of group-based Otago exercise program on fear of falling and physical function among older adults living in nursing homes: A pilot trial.

This pilot trial explored the feasibility of group-based Otago exercise program (OEP) and its impact on fear of falling (FOF) and physical function among Chinese older adults living in nursing homes. The intervention group received group-based OEP for 12 weeks, while the control group received routine care. The modified Survey of Activities and Fear of Falling in the Elderly (mSAFFE), timed Up and Go test (TUG), four-stage Balance test (FSBT), and 30 seconds sit-to-stand test (30s-SST) were used. After twelve weeks, we found that the intervention group had better outcomes than the control group in mSAFFE, TUG, FSBT and 30s-SST (p<0.05). Also, we compared the pretest-posttest results within the two groups, respectively. We found that, within the intervention group, the outcomes of mSAFFE, TUG, FSBT, and 30s-SST become significantly better after twelve weeks, but within the control group, the outcomes of TUG, FSBT, and 30s-SST become significantly worse. Our findings demonstrated that a group-based OEP was feasible and acceptability among Chinese older adults living in nursing homes and the group-based OEP could improve FOF and physical function among those older adults.

Comparison of Core Muscle Asymmetry Using Spine Balance 3D in Patients with Arthroscopic Shoulder Surgery: A STROBE-Compliant Cross-Sectional Study.

Background and Objectives: Joint immobilization after shoulder surgery can cause an imbalance in the periscapular muscles and affect the kinetic chain throughout the body. There is a difference in core muscle stability because of the asymmetry of the lower extremity muscles. However, the difference due to the asymmetry of the upper-extremity muscles has not been studied extensively. The purpose of this study is to investigate the effect of joint immobilization on the symmetry of the core muscles involved in proximal stability for distal mobility. Materials and Methods: Fifty-five patients who underwent arthroscopic shoulder surgery participated in this study. Core muscle asymmetry (CMA) was measured using a body tilt device. The evaluation variables were analyzed according to the surgical site based on the direction of the core muscle ratio and core muscle state ratio. Results: No differences in CMA were found based on the surgical site (p > 0.05). As a result of the additional subanalysis, significant differences in sex and postoperative day were established (p < 0.05). CMA was low during the intensive postoperative rehabilitation period. However, sex-related differences were greater in males than in females. Conclusions: The clinical results suggest that core muscle training is necessary to reduce CMA during rehabilitation after the immobilization period has elapsed.

A randomized controlled trial to determine whether beta-hydroxy-beta-methylbutyrate and/or eicosapentaenoic acid improves diaphragm and quadriceps strength in critically Ill mechanically ventilated patients.

BACKGROUND: Intensive care unit acquired weakness is a serious problem, contributing to respiratory failure and reductions in ambulation. Currently, there is no pharmacological therapy for this condition. Studies indicate, however, that both beta-hydroxy-beta-methylbutyrate (HMB) and eicosapentaenoic acid (EPA) increase muscle function in patients with cancer and in older adults. The purpose of this study was to determine whether HMB and/or EPA administration would increase diaphragm and quadriceps strength in mechanically ventilated patients. METHODS: Studies were performed on 83 mechanically ventilated patients who were recruited from the Medical Intensive Care Units at the University of Kentucky. Diaphragm strength was assessed as the trans-diaphragmatic pressure generated by supramaximal magnetic phrenic nerve stimulation (PdiTw). Quadriceps strength was assessed as leg force generated by supramaximal magnetic femoral nerve stimulation (QuadTw). Diaphragm and quadriceps thickness were assessed by ultrasound. Baseline measurements of muscle strength and size were performed, and patients were then randomized to one of four treatment groups (placebo, HMB 3 gm/day, EPA 2 gm/day and HMB plus EPA). Strength and size measurements were repeated 11 days after study entry. ANCOVA statistical testing was used to compare variables across the four experimental groups. RESULTS: Treatments failed to increase the strength and thickness of either the diaphragm or quadriceps when compared to placebo. In addition, treatments also failed to decrease the duration of mechanical ventilation after study entry. CONCLUSIONS: These results indicate that a 10-day course of HMB and/or EPA does not improve skeletal muscle strength in critically ill mechanically ventilated patients. These findings also confirm previous reports that diaphragm and leg strength in these patients are profoundly low. Additional studies will be needed to examine the effects of other anabolic agents and innovative forms of physical therapy. TRIAL REGISTRATION: ClinicalTrials.gov, NCT01270516. Registered 5 January 2011, https://clinicaltrials.gov/ct2/show/NCT01270516?term=Supinski&draw=2&rank=4 .

The 30-s chair stand test can be a useful tool for screening sarcopenia in elderly Japanese participants.

BACKGROUND: Low muscle strength has been focused on as an essential characteristic of sarcopenia, and the 30-s chair stand test (CS-30) could be a particularly useful test for assessing muscle strength. While it is speculated to be a beneficial tool for the assessment of sarcopenia, this remains to be verified. In this study, we examined the reliability and optimal diagnostic score of the CS-30 for assessing sarcopenia in elderly Japanese participants. METHODS: This cross-sectional study included 678 participants (443 females and 235 males) who underwent the test for sarcopenia as per the Asian Working Group for Sarcopenia (AWGS) 2019, the CS-30 test, and the isometric knee-extension muscle strength test. ROC analysis was used to estimate the optimal CS-30 scores at which sarcopenia was detected. RESULTS: CS-30 scores were positively associated with sarcopenia (OR: 0.88; 95% CI:0.82-0.93). The AUC of the CS-30 for sarcopenia definition were 0.84 (p < 0.001) for females and 0.80 (p < 0.001) for males. The optimal number of stands in the CS-30 that predicted sarcopenia was 15 for females (sensitivity, 76.4%; specificity, 76.8%) and 17 for males (sensitivity, 75.0%; specificity, 71.7%). CONCLUSIONS: The CS-30 was found to be a reliable test for sarcopenia screening in the elderly Japanese population.

Muscle synergy for upper limb damping behavior during object transport while walking in healthy young individuals.

Transporting an object during locomotion is one of the most common activities humans perform. Previous studies have shown that continuous and predictive control of grip force, along with the inertial load force of the object, is required to complete this task successfully. Another possible CNS strategy to ensure the dynamic stability of the upper limb is to modify the apparent stiffness and damping via altered muscle activation patterns. In this study, the term damping was used to describe a reduction in upper limb vertical oscillation amplitude to maintain the orientation of the hand-held object. The goal of this study was to identify the neuromuscular strategy for controlling the upper limb during object transport while walking. Three-dimensional kinematic and surface electromyography (EMG) data were recorded from eight, right-handed, healthy young adults who were instructed to walk on a treadmill while carrying an object in their dominant/non-dominant hand, with dominant/non-dominant arm positioning but without an object, and without any object or instructed arm-positioning. EMG recordings from the dominant and non-dominant arms were decomposed separately into underlying muscle synergies using non-negative matrix factorization (NNMF). Results revealed that the dominant arm showed higher damping compared to the non-dominant arm. All muscles showed higher mean levels of activation during object transport except for posterior deltoid (PD), with activation peaks occurring around or slightly before heel contact. The muscle synergy analysis revealed an anticipatory stabilization of the shoulder and elbow joints through a proximal-to-distal muscle activation pattern. These activations appear to play an essential role in maintaining the stability of the carried object in addition to the adjustment of grip force against the perturbations caused by heel contact during walking.

Characteristics of multi-channel Br(E)-MsEP waveforms for the lower extremity muscles in thoracic spine surgery: comparison based on preoperative motor status.

PURPOSE: To evaluate the characteristics of brain-evoked muscle action potential [Br(E)-MsEP] waveforms of lower limb muscles in thoracic spine surgery. METHODS: The subjects were 159 patients who underwent thoracic spine surgery with intraoperative Br(E)-MsEP monitoring from January 2009 to December 2015, using a total of 2226 muscles in the extremities. The waveform derivation rate for each lower extremity muscle was examined at baseline and intraoperatively. Data were interpreted based on the preoperative motor status. RESULTS: The preoperative ambulatory and non-ambulatory rates were 38% (60/159, McCormick grades I and II) and 62% (99/159, grades III-V), respectively. Eleven cases (all non-ambulatory) had undetectable baseline waveforms in all muscles, and in 19 cases (12%) a baseline waveform could only be derived from the abductor hallucis (AH). The waveform derivation rate in all lower limb muscles was significantly higher in ambulatory cases (p < 0.05), and the rates for the AH were the highest in both groups (p < 0.05). Postoperative paralysis occurred in 31 cases (19%). A decrease in intraoperative amplitude of ≥ 70% from baseline occurred in 54 cases and had sensitivity of 100% and specificity of 82% for prediction of postoperative motor deficit. CONCLUSIONS: This is the first study of Br(E)-MsEP waveforms for each lower limb muscle based on preoperative ambulatory status. Detection of waveforms from distal muscles was still possible in a case with preoperative motor deficit, and the AH had an especially high derivation rate, even in cases with preoperative muscle weakness. Collectively, the results support use of Br(E)-MsEP monitoring using the AH in the lower extremities.

Effect of a lower limb strength training programme on physical activity during the snowy season among community-dwelling elderly individuals.

Background: Promoting continued physical activity during winter in snowy-cold regions would be of benefit as a health promotion strategy among elderly individuals. Aim: To evaluate the effect of a lower limb strength training programme for elderly individuals on the daily step counts during the snowy season. Subjects and methods: Fourteen community-dwelling elderly individuals were recruited from a snowy-cold region of northern Japan. Methods: Daily step counts were measured during the snowy season in 2018 (with no exercise intervention) and 2019 (after the exercise intervention). Physical function was measured before and after the intervention, including body mass index, 30-s chair test, grip strength, normal gait speed, short-test battery for locomotive syndrome, Kihon checklist and 25-question geriatric locomotive function scale. Results: The study group included 11 women and three men (78.6 ± 5.2 years old). The exercise intervention improved physical function, with a significant increase in step count among individuals with lower baseline strength. Improved lower limb strength positively correlated with an increase in step count. Conclusion: Lower limb muscle strengthening is an effective intervention to improve physical activity during the snowy season among community-dwelling elderly.

Inter-day test-retest reliability and feasibility of isokinetic, isometric, and isotonic measurements to assess quadriceps endurance in people with chronic obstructive pulmonary disease: A multicenter study.

The aims were to determine reliability and feasibility of measurements to assess quadriceps endurance in people with chronic obstructive pulmonary disease. Sixty participants (forced expiratory volume in one second (mean ± standard deviation) 55 ± 18% of predicted, age 67 ± 8 years) were tested in an inter-day, test-retest design. Isokinetic, isometric, and isotonic protocols were performed using a computerized dynamometer. Test-retest relative and absolute reliability was determined via intraclass correlation coefficient (ICC), coefficient of variation (CV%), and limits of agreement (LoA%). Isokinetic total work demonstrated very high relative reliability (ICC: [95% confidence interval] = 0.98 [0.94-0.99]) and the best absolute reliability (CV% (LoA%) = 6.5% (18.0%)). Isokinetic fatigue index, isometric, and isotonic measures demonstrated low-to-high relative reliability (ICC = 0.64 [0.46-0.77], 0.88 [0.76-0.94], 0.91 [0.85-0.94]), and measures of absolute reliability (CV% (LoA%)) were 20.3% (56.4%), 14.9% (40.8%), and 15.8% (43.1%). For isokinetic total work and isometric measurements, participants performed better on retest (4.8% and 10.0%, respectively). The feasibility was similar across protocols with an average time consumption of less than 7.5 minutes. In conclusion, isokinetic, isometric, and isotonic measurements of quadriceps endurance were feasible to a similar extent and presented low-to-very high relative reliability. Absolute reliability seems to favor isokinetic total work measurements.

Muscle Function in Osteogenesis Imperfecta Type IV.

Results of previous studies suggest that children and adolescents with osteogenesis imperfecta (OI) type IV have muscle force deficits. However, muscle function remains to be objectively quantified in this population. This study aimed to assess upper and lower extremity muscle function in patients with OI type IV. It was carried out in the outpatient department of a pediatric orthopedic hospital; 27 individuals with OI type IV (7-21 years; 13 males), 27 age- and sex-matched individuals with OI type I, and 27 age- and sex-matched controls. Upper extremity muscle force was assessed with hydraulic hand dynamometry, and lower extremity muscle function (peak force per body weight and peak power per body mass) was measured by mechanography through five tests: multiple two-legged hopping, multiple one-legged hopping, single two-legged jump, chair-rise test, and heel-rise test. Upper-limb grip force was normal for patients with OI type IV when compared to height and sex reference data (average z-score = 0.17 ± 1.30; P = 0.88). Compared to age- and sex-matched controls, patients with OI type IV had approximately 30% lower-limb peak force and 50% peak power deficits (P values <0.05). At the lower-limb level, they had a 50% lower peak power than age- and sex-matched patients with OI type I (P < 0.05). Patients with OI type IV have normal upper-limb muscle force but a muscle function deficit at the lower-limb level. These results suggest that lower-limb muscle weakness may contribute to functional deficits in these individuals.

A novel, bounding gait in swimming turtles: implications for aquatic locomotor diversity.

Turtles are an iconic lineage in studies of animal locomotion, typifying the use of slow, alternating footfalls during walking. Alternating movements of contralateral limbs are also typical during swimming gaits for most freshwater turtles. Here, we report a novel gait in turtles, in which the pleurodire Emydura subglobosa swims using a bounding gait that coordinates bilateral protraction of both forelimbs with bilateral retraction of both hindlimbs. Use of this bounding gait is correlated with increased limb excursion and decreased stride frequency, but not increased velocity when compared with standard swimming strokes. Bounding by E. subglobosa provides a second example of a non-mammalian lineage that can use bounding gaits, and may give insight into the evolution of aquatic flapping. Parallels in limb muscle fascicle properties between bounding turtles and crocodylids suggest a possible musculoskeletal mechanism underlying the use of bounding gaits in particular lineages.

Associations of dietary patterns with bone mass, muscle strength and balance in a cohort of Australian middle-aged women.

Influences of dietary patterns on musculoskeletal health are poorly understood in middle-aged women. This cross-sectional analysis from a cohort of 347 women (aged 36-57 years) aimed to examine associations between dietary patterns and musculoskeletal health outcomes in middle-aged women. Diet was measured by the Cancer Council of Victoria FFQ. Total body bone mineral content (TB BMC), femoral neck and lumbar spine bone density (dual-energy X-ray absorptiometry), lower limbs muscle strength (LMS) and balance tests (timed up and go test, step test, functional reach test (FRT) and lateral reach test) were also measured. Exploratory factor analysis was used to identify dietary patterns and scores for each pattern generated using factor loadings with absolute values ≥0·20. Associations between food pattern scores and musculoskeletal outcomes were assessed using multivariable linear regression. Three dietary patterns were identified: 'Healthy' (high consumption of a plant-based diet - vegetables, legumes, fruit, tomatoes, nuts, snacks, garlic, whole grains and low intake of high-fat dairy products), 'high protein, high fat' (red meats, poultry, processed meats, potatoes, cruciferous and dark-yellow vegetables, fish, chips, spirits and high-fat dairy products) and 'Processed foods' (high intakes of meat pies, hamburgers, beer, sweets, fruit juice, processed meats, snacks, spirits, pizza and low intake of cruciferous vegetables). After adjustment for confounders, Healthy pattern was positively associated with LMS, whereas Processed foods pattern was inversely associated with TB BMC and FRT. The associations were not significant after accounting for multiple comparisons. There were no associations with any other outcomes. These results suggest that maintaining a healthy diet could contribute to bone acquisition, muscle strength and balance in adult life. However, while they provide some support for further investigating dietary strategies for prevention of age-related loss of muscle and deterioration in balance, the exploratory nature of the analyses means that confirmation in longitudinal studies and/or trials with pre-specified hypotheses is needed.

Axial and limb muscle development: dialogue with the neighbourhood.

Skeletal muscles are part of the musculoskeletal system which also includes nerves, tendons, connective tissue, bones and blood vessels. Here we review the development of axial and limb muscles in amniotes within the context of their surrounding tissues in vivo. We highlight the reciprocal dialogue mediated by signalling factors between cells of these adjacent tissues and developing muscles and also demonstrate its importance from the onset of muscle cell differentiation well into foetal development. Early embryonic tissues secrete factors which are important regulators of myogenesis. However, later muscle development relies on other tissue collaborators, such as developing nerves and connective tissue, which are in turn influenced by the developing muscles themselves. We conclude that skeletal muscle development in vivo is a compelling example of the importance of reciprocal interactions between developing tissues for the complete and coordinated development of a functional system.