The effects of aerobic gymnastics training on performance-related variables in an elite athlete: a 2-year follow-up study.

This study investigates individual performance adaptations on 2 years of training between European Aerobics Championships. An elite, 22-year-old aerobic gymnast performed postural coordination test, Y-Balance test, squat and countermovement jumps, 60 s test of repeated jumps, an isokinetic leg muscle strength test, and the Wingate test. Postural stability and flexibility improved in terms of increased distance achieved in the Y-Balance test in the anterior (by 6.3%), posteromedial (by 2%), and posterolateral (by 4.8%) directions. Lower limb muscular endurance also increased, which can be corroborated by a reduced fatigue index in the 60 s test of repeated jumps (from 42% to 27% after the 1st and to 22% after the 2nd year of training). In addition, mean power increased during dominant (by 23.2% at 60°/s and by 18.5% at 180°/s) and non-dominant leg extension (by 4.9% at 180°/s and by 15.5% at 300°/s), plus dominant leg flexion (by 2.0% at 60°/s and by 6.9% at 300°/s). Similarly, peak torque/body weight ratio increased during dominant (by 24.9% at 60°/s, by 11.5% at 180°/s, and by 2.1% at 300°/s) and non-dominant leg extension (by 0.5% at 60°/s and by 6.4% at 300°/s), plus dominant leg flexion (by 1.7% at 60°/s and by 5.4% at 300°/s). However, 2 years of training failed to show any significant improvements in the explosive power of lower limbs and anaerobic performance. These findings indicate that general aerobic gymnastics training without any specific inputs leads to performance adaptation, namely, in abilities closely related to competition routine (dynamic balance and strength endurance of lower limbs).

Accuracy of a portable lower-limb muscle strength measuring device with a training function.

[Purpose] Quadriceps muscle strength is essential for daily living activities. Therefore, we developed a compact and simple lower limb muscle strength measuring device (LocomoScan [LCS]). This study aimed to compare LCS with other instruments to analyze its simplicity, reproducibility, and accuracy. [Participants and Methods] One hundred and four healthy university students (56 males and 48 females) were included in the study. The knee extension force was measured using LCS, and the knee extension torque was measured using other devices (Cybex). In addition, lower leg muscle mass was measured using a body composition meter. The reproducibility of LCS and the correlation between the knee extension torque and lower leg muscle mass were evaluated. [Results] The measurement reproducibility of LCS was significantly higher. The knee extension force confirmed the proportional relative reliability of Cybex with knee extension torque. A relationship between knee extension force and lower limb muscle mass was also observed, indicating that muscle mass cannot be estimated as muscle strength. [Conclusion] The high reproducibility of the knee extension force measurement using LCS demonstrates its potential as a portable alternative instrument for muscle strength measurement in clinical practice. Therefore, LCS device is a simple and effective tool for assessing muscle strength.

Content of Lead and Cadmium in the Tissues and Organs of the Wild Mallard Duck (Anas platyrhynchos L.) Depending on the Region of Poland Where It Is Harvested.

A property common to heavy metals is that even in small concentrations they can exert toxic effects on living organisms, including humans. The aim of this study was to analyze the quality of the tissues and organs of wild mallard ducks (Anas platyrhynchos L.) by estimating the potential hygiene and toxicological hazard associated with the concentrations of lead and cadmium in these tissues and organs, as well as the influence of the birds' sex and place of origin on these parameters. A significantly higher average lead content was noted in the breast muscles and the livers of the mallards harvested in the Leszno hunting district compared to the birds from the Siedlce hunting district. A higher average cadmium concentration was recorded in the breast and leg muscles of the mallards harvested in the Leszno hunting district than the Siedlce hunting district. The concentration of cadmium in the tissues and organs of the mallards harvested in the Siedlce or the Leszno hunting district did not exceed the acceptable limits for the muscles and livers of slaughtered animals. This study found no significant effect of the sex of the wild crossbreeds on the content of lead and cadmium in tissues and organs. This study showed that the mallard has a measurable response to environmental pollution with lead and cadmium, and therefore it is a species that could to some extent be used as a bioindicator of the level of contamination of the environment with these xenobiotics. The ban on the use of lead pellets as ammunition in Poland may largely limit the degree of lead contamination of the tissues and organs of mallards.

Perceived Exertion Correlates with Multiple Physiological Parameters During Cardiopulmonary Exercise Testing.

The purpose of this study was to investigate the relationship of the Borg scale score with leg-muscle oxygenated haemoglobin (O2Hb) and deoxygenated haemoglobin (HHb) levels on near infrared spectroscopy (NIRS) and the work rate, heart rate (HR), oxygen uptake (VO2) and minute ventilation (VE) during supine cardiopulmonary exercise testing (CPET) in healthy adult men. We also investigated the relationships between the leg-muscle O2Hb and HHb levels and the work rate during supine CPET. Fifteen healthy male volunteers (mean age, 20.7 ± 0.6 years; mean height, 172.1 ± 5.7 cm; mean body weight, 61.7 ± 6.6 kg) participated in this study. The cardiopulmonary and NIRS parameters were assessed during each minute of supine CPET and at the end of the test. The Borg scale score significantly correlated with the work rate, HR, VO2, and VE during supine CPET (Rs = 0.86-0.94, p < 0.05). Furthermore, the Borg scale score significantly correlated with the leg-muscle O2Hb and HHb levels during supine CPET (Rs = -0.6, and 0.8, respectively; p < 0.05). The leg-muscle O2Hb and HHb levels had significant correlations with the work rate (R = -0.62 and 0.8, respectively; p < 0.05). The Borg scale score may be used to determine the rating of perceived exertion, whole-body fatigue and local-muscle fatigue during supine exercise. Moreover, leg-muscle oxygenation is associated with the work rate in supine exercise, similar to that observed in upright exercise.

Analysis of the Fatty Acid Profile of the Tissues of Hunted Mallard Ducks (Anas platyrhynchos L.) from Poland.

The aim of the study was to analyse the fatty acid profile of selected tissues of mallard ducks (Anas platyrhynchos L.), in relation to where they were obtained and their sex, with regard to the human diet. The study was carried out on material obtained from mallard ducks from two study areas: the Siedlce hunting district and the Leszno hunting district. The research material was the breast and leg muscles of 28 mallards. The samples were frozen and stored at −20 °C. The fatty acid profiles in the biological samples were determined by selected ion recording (SIR). The results showed significantly (p < 0.05) lower average levels of saturated fatty acids (SFAs) and monounsaturated fatty acids (MUFAs) and significantly higher (p < 0.05) average levels of polyunsaturated fatty acids (PUFAs), n-6 PUFAs, and n-3 PUFAs in the breast muscles of the mallards obtained in the Siedlce hunting district. This in conjunction with the higher (p < 0.05) hypocholesterolaemic/hypercholesterolaemic index (h/H) in the leg muscles and lower (p < 0.05) atherogenic and thrombogenic indices (AI and TI) in the leg and breast muscles of mallards in the Siedlce hunting district indicate the higher health-promoting value of the meat of ducks from this region. The average n-6/n-3 PUFA ratio in the breast muscles was significantly (p < 0.05) higher in mallards obtained in the Leszno hunting district. Males of the species had a significantly (p < 0.05) higher average n-6/n-3 PUFA ratio in the breast muscles than females. The PUFA/SFA ratio was significantly (p < 0.05) higher in the leg muscles of the female mallards than in the males.

Reliability of lower leg muscle thickness measurement along the long axis of the muscle using ultrasound imaging, in a sitting position.

[Purpose] To verify the reliability and validity of lower leg muscle thickness (MT) assessment along the muscle's long axis using ultrasound imaging (USI) in a sitting position. [Participants and Methods] Twenty healthy adult female participants (aged, 20.3 ± 0.9 years) were included in the study. Intra- and inter-examiner reliability of the proximal, middle, and distal MT of the tibialis anterior (TA) and medial head of the gastrocnemius (GM) were verified using USI in a sitting position. Additionally, the relationship between MT measurement using USI and muscle cross-sectional area (MCSA) measurement using magnetic resonance imaging (MRI), as well as the ankle joint's maximum muscle strength, were examined. [Results] The reliability of TA and GM MT measurement using USI was high for all regions. The relationship between MCSA measurement using MRI and MT measurement using USI showed a significant correlation in all the regions for both muscles. The relationship between ankle muscle strength and USI of MT was not significantly correlated in any region for both muscles. [Conclusion] Measurement of MT using USI is reliable and valid for MCSA, but must be combined with assessments of other factors for muscle strength.

31 P MRSI at 7 T enables high-resolution volumetric mapping of the intracellular magnesium ion content in human lower leg muscles.

PURPOSE: The non-invasive determination of the free magnesium ion concentration ([Mg2+free ]) using 31 P MRSI in vivo is of interest in research on various pathologies, e.g. diabetes. The purpose of this study was to demonstrate the potential of 31 P MRSI at 7 T to enable volumetric, high-resolution mapping of [Mg2+free ]. METHODS: 3D 31 P MRSI datasets from the lower leg of three healthy volunteers were acquired at B0  = 7 T with a nominal spatial resolution of (8 × 8 × 16) mm3 in 56 min. Volumetric [Mg2+free ] maps were calculated based on the quantified local chemical shift difference between the α- and ß-resonance of adenosine triphosphate (ATP) considering also local pH values. Mean [Mg2+free ] values from three different muscle groups were compared. To demonstrate the potential of reducing the measurement time, the analysis was repeated on the acquired MRSI data retrospectively reconstructed with fewer averages. RESULTS: The generated [Mg2+free ] maps revealed local differences, and mean [Mg2+free ] values of (1.08 ± 0.03) mM were found in the tibialis anterior, (0.91 ± 0.04) mM in the soleus and (0.98 ± 0.03) mM in the gastrocnemius medialis. The time-reduced 28-min scan resulted in comparable [Mg2+free ] maps, and mean values being in agreement with the values from the 56-min scan. CONCLUSION: 31 P MRSI at 7 T enables volumetric, high-resolution mapping of free magnesium ion content in human lower leg muscles. The measurement time of the 31 P MRSI acquisition can be reduced to 28 min, opening the potential to apply volumetric [Mg2+free ] mapping for the investigation of pathologies with altered magnesium homeostasis.

Analysis of the molecular mechanism of inosine monophosphate deposition in Jingyuan chicken muscles using a proteomic approach.

Inosine monophosphate (IMP) is an indicator of meat taste, and the molecular mechanism underlying IMP deposition in muscle tissues is important to developing superior poultry breeds. The aim of this study was to identify the key proteins regulating IMP deposition in different muscle groups of 180-day-old Jingyuan chickens (Hen) using a proteomics-based approach. We identified 1,300 proteins in the muscle tissues of Jingyuan chickens, of which 322 were differentially expressed between the breast and leg muscles (129 proteins were highly expressed in breast muscles and 193 proteins were highly expressed in leg muscles). PGM1, PKM2, AK1, AMPD1, and PurH/ATIC were among the differentially expressed proteins (DEPs) involved in the purine metabolism pathway, of which purH was highly expressed in leg muscles, while the others were highly expressed in breast muscles. The proteomics screening results were verified by PRM, qPCR, and western blotting, showing consistency with the proteomics results. Our findings are not only significant in terms of protecting the Jingyuan chicken germplasm resources, but also provide the molecular basis for generating high-quality broiler chicken breeds.

Metabolomic signatures for the longitudinal reduction of muscle strength over 10 years.

BACKGROUND: Skeletal muscles are essential components of the neuromuscular skeletal system that have an integral role in the structure and function of the synovial joints which are often affected by osteoarthritis (OA). The aim of this study was to identify the baseline metabolomic signatures for the longitudinal reduction of muscle strength over 10 years in the well-established community-based Tasmanian Older Adult Cohort (TASOAC). METHODS: Study participants were 50-79 year old individuals from the TASOAC. Hand grip, knee extension, and leg strength were measured at baseline, 2.6-, 5-, and 10-year follow-up points. Fasting serum samples were collected at 2.6-year follow-up point, and metabolomic profiling was performed using the TMIC Prime Metabolomics Profiling Assay. Generalized linear mixed effects model was used to identify metabolites that were associated with the reduction in muscle strength over 10 years after controlling for age, sex, and BMI. Significance level was defined at α=0.0004 after correction of multiple testing of 129 metabolites with Bonferroni method. Further, a genome-wide association study (GWAS) analysis was performed to explore if genetic factors account for the association between the identified metabolomic markers and the longitudinal reduction of muscle strength over 10 years. RESULTS: A total of 409 older adults (50% of them females) were included. The mean age was 60.93±6.50 years, and mean BMI was 27.12±4.18 kg/m2 at baseline. Muscle strength declined by 0.09 psi, 0.02 kg, and 2.57 kg per year for hand grip, knee extension, and leg strength, respectively. Among the 143 metabolites measured, 129 passed the quality checks and were included in the analysis. We found that the elevated blood level of asymmetric dimethylarginine (ADMA) was associated with the reduction in hand grip (p=0.0003) and knee extension strength (p=0.008) over 10 years. GWAS analysis found that a SNP rs1125718 adjacent to WISP1gene was associated with ADMA levels (p=4.39*10-8). Further, we found that the increased serum concentration of uric acid was significantly associated with the decline in leg strength over 10 years (p=0.0001). CONCLUSION: Our results demonstrated that elevated serum ADMA and uric acid at baseline were associated with age-dependent muscle strength reduction. They might be novel targets to prevent muscle strength loss over time.

Leg Muscle Strength Correlates with Gait Performance in Advanced Parkinson Disease.

Objective Leg muscle strength (LMS) is decreased in early-stage Parkinson disease (PD) patients and is associated with slower walking and falls. However, LMS in advanced PD has not been well investigated. The purpose of this study was to evaluate LMS in advanced PD patients and its effects on gait performance, activities of daily living, and the cognitive function. Methods The medical records of 132 patients with idiopathic advanced PD [Hoehn and Yahr (H&Y) stages 3 and 4] with a mean disease duration of 9.6 years were retrospectively reviewed. Leg extensor muscle strength of the patients was measured using a Strength Ergo 240. The associations between the LMS and gait performance, Barthel index, H&Y stage, and Mini-Mental State Examination (MMSE) score were analyzed. Results A Spearman's correlation analysis showed that LMS was correlated with the sex, age, age of disease onset, H&Y stage, Barthel index, MMSE score, and gait parameters. A multivariable linear regression analysis for identifying predictors of LMS showed that the gait velocity (ß=0.377), Barthel index (ß=0.281), sex (ß=-0.187), and disease duration (ß=-0.155) were significant. A receiver operating characteristic curve analysis for discriminating between H&Y stage 3 and 4 was performed for LMS; the area under the curve was 0.774 (95% confidence interval=0.696-0.851). Conclusions LMS was strongly associated with multiple domains of clinical characteristics, especially gait velocity and the Barthel index. Our study also suggested that LMS can be a predictor of PD progression.

Relationship Between Body Segment Mass and Running Performance in Well-Trained Endurance Runners.

This study examined the relationship between body segment mass and running performance in endurance runners. The total (muscle, fat, and bone masses), lean (muscle mass), and fat masses of the leg, arm, and trunk segments in 37 well-trained endurance runners were measured using dual-energy X-ray absorptiometer. The relative segment mass was calculated by normalizing the absolute mass to body mass. There were no significant correlations between absolute total, lean, and fat masses of all 3 segments and personal best 5000-m race time. No significant correlations were also observed between all 3 relative masses of the arm segment and personal best 5000-m race time. In contrast, medium positive correlations were observed between the relative total and lean masses of the leg segment and personal best 5000-m race time (r = .387 and .335, respectively, both P ≤ .031). Furthermore, large negative correlations were observed between the relative total and lean masses of the trunk segment and personal best 5000-m race time (r = -.500 and -.548, respectively, both P ≤ .002). These findings suggest that a mass distribution with smaller leg mass and greater trunk mass may be advantageous for achieving better running performance in endurance runners.

Unusual bilateral variation of the flexor digitorum accessorius longus muscle and its relation on tarsal tunnel syndrome.

PURPOSE: During standard anatomical dissection for a medical anatomy course, we encountered an unusual bilateral variant of a unipennate flexor digitorum accessorius longus (FDAL) muscle, a supernumery muscle of the deep posterior leg and medial ankle. METHODS: We documented the muscles course and measured the diameter and length of the FDAL muscle belly, as well as the full length of its tendinous attachments. RESULTS: On both right and left legs, the FDAL originated from the proximal posterior fibula and distal one-third of the flexor hallucis longus muscle. The tendon had a distal attachment on the flexor digitorum longus (FDL) tendon and traveled with the FDL tendon as it inserted on the third distal phalanx. The left FDAL full length was 42.54 cm; the length of the muscle belly was 16.26 cm; and the circumference of the muscle belly was 4.44 cm. The right FDAL full length was 44.20 cm; the length of muscle belly was 12.06; and the circumference (belly) was 4.44 cm. Surrounding musculature and neurovasculature follow standard anatomical courses. CONCLUSION: This anatomical documentation provides opportunities for clinicians to consider mechanical influences of the FDAL on plantar foot function and further consider the accessory ankle muscles that have the potential to cause compressive neuropathies such as tarsal tunnel syndrome.

Fragmentary Hypnic Myoclonus and Other Isolated Motor Phenomena of Sleep.

Excessive fragmentary hypnic myoclonus, hypnic jerks, hypnagogic foot tremor, alternating leg muscle activation, and sleep-related cramps are less known sleep-related motor disorders (SRMDs). These manifestations are frequently missed or misinterpreted polygraphic findings that can be frequently confused with the more frequent SRMDs. These symptoms can present as isolated motor symptoms but can be also the cause of otherwise cryptogenic insomnias and somnolence. Expanding the knowledge on these isolated symptoms and defining their polygraphic and clinical features are essential for their identification. However, clear cut-offs to discern between the isolated phenomenon and the disorder are still to be found.

Distributed processing of load and movement feedback in the premotor network controlling an insect leg joint.

In legged animals, integration of information from various proprioceptors in and on the appendages by local premotor networks in the central nervous system is crucial for controlling motor output. To ensure posture maintenance and precise active movements, information about limb loading and movement is required. In insects, various groups of campaniform sensilla (CS) measure forces and loads acting in different directions on the leg, and the femoral chordotonal organ (fCO) provides information about movement of the femur-tibia (FTi) joint. In this study, we used extra- and intracellular recordings of extensor tibiae (ExtTi) and retractor coxae (RetCx) motor neurons (MNs) and identified local premotor nonspiking interneurons (NSIs) and mechanical stimulation of the fCO and tibial or trochanterofemoral CS (tiCS, tr/fCS), to investigate the premotor network architecture underlying multimodal proprioceptive integration. We found that load feedback from tiCS altered the strength of movement-elicited resistance reflexes and determined the specificity of ExtTi and RetCx MN responses to various load and movement stimuli. These responses were mediated by a common population of identified NSIs into which synaptic inputs from the fCO, tiCS, and tr/fCS are distributed, and whose effects onto ExtTi MNs can be antagonistic for both stimulus modalities. Multimodal sensory signal interaction was found at the level of single NSIs and MNs. The results provide evidence that load and movement feedback are integrated in a multimodal, distributed local premotor network consisting of antagonistic elements controlling movements of the FTi joint, thus substantially extending current knowledge on how legged motor systems achieve fine-tuned motor control.NEW & NOTEWORTHY Proprioception is crucial for motor control in legged animals. We show the extent to which processing of movement (fCO) and load (CS) signals overlaps in the local premotor network of an insect leg. Multimodal signals converge onto the same set of interneurons, and our knowledge about distributed, antagonistic processing is extended to incorporate multiple modalities within one perceptual neuronal framework.

Hand Grip and Leg Muscle Strength in Hemodialysis Patients and Its Determinants.

BACKGROUND: Chronic kidney disease is associated with chronic inflammation and progressive loss of peripheral muscle strength and the ability to exercise, and these changes are highly pronounced in patients receiving hemodialysis (HD). We evaluated hand grip strength (HGS) and leg muscle strength (LMS) in patients receiving HD and attempted to identify factors associated with muscle strength. METHODS: We screened HGS (opposite the fistula side) and LMS (both sides) in HD patients at a single center (n = 112) by using digital hand and leg dynamometers (T.K.K. 5401 and 5710e/5715, Takei Scientific Instruments Co. Ltd., Niigata, Japan). RESULTS: The mean age of patients was 62.6 years, and 73.2% of the patients were male. Diabetes was the cause of kidney failure in 50% of the patients, and the median HD vintage was 34 months. A total of 77.7% of patients reported that they participated in regular home-based exercise, and 29.5% of patients regularly participated in hospital-based resistance exercise. HGS and LMS showed good correlation (r = 0.715, P < 0.001). HGS (25.1 vs. 17.0 kg) and LMS (30.1 vs. 20.4 kg) were greater in males (P < 0.001 and P < 0.001, respectively) than in females. Older patients (≥ 60 years) showed less LMS than younger patients in both males and females (P = 0.012 and P = 0.037, respectively), but HGS did not differ according to age. Patients performing regular home- or hospital-based exercise showed higher HGS than those who did not exercise (24.2 vs. 18.6 kg, P = 0.011), but LMS was not significantly different (29.3 vs. 23.6 kg, P = 0.185). Multiple linear regression analysis proved that male sex, younger age, and any type of exercise were factors associated with improved HGS and LMS. Groups of older age (≥ 60 years), male sex, and shorter duration of HD (< median) benefitted more from exercise. CONCLUSION: Sex, age, and exercise were the most important determinants of muscle strength in HD patients. We need to encourage patients to engage in regular home or group exercise from the beginning of dialysis and introduce new feasible forms of exercise for HD patients.

Simultaneous T1 , T2 , and T1ρ relaxation mapping of the lower leg muscle with MR fingerprinting.

PURPOSE: To develop a novel MR-fingerprinting (MRF) pulse sequence that is insensitive to B1+ and B0 imperfections for simultaneous T1 , T2 , and T1ρ relaxation mapping. METHODS: We implemented a totally balanced spin-lock (TB-SL) module to encode T1ρ relaxation into an existing MRF framework that encoded T1 and T2 . The spin-lock module used two 180° pulses with compensatory phases to reduce T1ρ sensitivity to B1 and B0 inhomogeneities. We compared T1ρ measured using TB-SL MRF in Bloch simulations, model agar phantoms, and in vivo experiments to those with a self-compensated spin-lock preparation module (SC-SL). The TB-SL MRF repeatability was evaluated in maps acquired in the lower leg skeletal muscle of 12 diabetic peripheral neuropathy patients, scanned two times each during visits separated by about 30 days. RESULTS: The phantom relaxation times measured with TB-SL and SC-SL MRF were in good agreement with reference values in regions with low B1 inhomogeneities. Compared with SC-SL, TB-SL MRF showed in experiments greater robustness against severe B1 inhomogeneities and in Bloch simulations greater robustness against B1 and B0 . We measured with TB-SL MRF an average T1 = 950.1 ± 28.7 ms, T2 = 26.0 ± 1.2 ms, and T1ρ = 31.7 ± 3.2 ms in skeletal muscle across patients. Bland-Altman analysis demonstrated low bias between TB-SL and SC-SL MRF and between TB-SL MRF maps acquired in two visits. The coefficient of variation was less than 3% for all measurements. CONCLUSION: The proposed TB-SL MRF sequence is fast and insensitive to B1+ and B0 imperfections. It can simultaneously map T1 , T2 , T1ρ , and B1+ in a single scan and can potentially be used to study muscle composition.

An association between the physical activity level and skeletal muscle mass index in female university students with a past exercise habituation.

OBJECTIVES: This study aims to investigate the association between skeletal muscle mass index (SMI) and physical activity among female university students who had exercise habituation in junior and high school. METHODS: The body composition of 120 Japanese female students was measured using the bioelectrical impedance analysis (BIA) method, and their physical activity level (PAL) was measured using a factorial method. Based on the 'Dietary Reference Intakes for Japanese' (DRIs-J), according to the Ministry of Health, Labour and Welfare, PAL (24-h energy consumption/basal metabolic rate) classifications were defined as low-PAL (PAL < 1.6), moderate-PAL (1.6 ≤ PAL < 1.9), and high-PAL (1.9 ≤ PAL < 2.2), respectively. RESULTS: Individuals with low-PAL had a significantly lower SMI, especially for the lower limb muscles, than individuals with moderate-PAL or higher. More than 50% of the individuals with currently low-PAL corresponded or tended to correspond to the SMI cut-off value defined by the Asian Working Group for Sarcopenia or the 2017 National Health and Nutrition Survey of Japan. Therefore, more than half of the female students with currently low-PAL, even those with an exercise habituation in the past, corresponded to the cut-off value for muscle loss in sarcopenia diagnosis, particularly in the lower limbs. CONCLUSIONS: These results suggest that it is important to maintain a moderate or higher level of physical activity in the DRIs-J classification, even for young women who used to exercise in the past, to maintain muscle mass accordingly.

Steady exercise improves hand grip and leg muscle strength in hemodialysis patients.

Sarcopenia due to chronic inflammation and biochemical disturbances in chronic kidney disease is severer and more prevalent in hemodialysis (HD) patients. We longitudinally evaluated the hand grip strength (HGS) and leg muscle strength (LMS) and evaluated the role of exercise in muscle strength in HD patients. We screened (January, n=127) and followed up (June, n=110 and December 2020, n=104). HGS and LMS at single center by using digital hand and leg dynamometer. HGS (24.2 kg vs. 15.5 kg) and LMS (32.8 kg vs. 22.5 kg) were better in men (P<0.001 and P<0.001, respectively). Older patients (≥60 years) showed decreased LMS than others in women (P=0.01). Patients who performed steady home- or hospital-based exercise showed marginally higher HGS (23.1 kg vs. 19.8 kg, P=0.07) and significantly higher LMS (33.7 kg vs. 25.9 kg, P=0.004). Steady exercise improved LMS throughout the study period (30.3 kg vs. 33.2 kg from Jan to Jun 2020, P=0.004; 30.3 kg vs. 34.2 kg from Jan to Dec 2020, P=0.014). Multiple linear regression analysis proved steady exercise was independently associated with better HGS and LMS. Steady exercise showed greater impact on LMS in male patients with longer HD vintage (≥44 months) and on HGS in younger male patients with shorter HD vintage (<44 months). Steady exercise was an important determinant of muscle strength in HD patients. We need to encourage patients to steadily perform regular home- or group-exercise before sarcopenia develops.

Coactivation pattern in leg muscles during treadmill walking in patients suffering from intermittent claudication.

BACKGROUND: In patients with peripheral arterial disease and presenting intermittent claudication (PAD-IC), the pain due to ischemia impacts gait parameters, particularly in cases of unilateral disease. Deterioration of gait parameters in a pathological context is frequently associated with increased coactivation (simultaneous activation of agonist and antagonist muscles around a joint). RESEARCH QUESTION: Does unilateral PAD-IC affect the coactivation pattern during walking? Does the coactivation pattern change with increasing pain intensity? METHOD: We evaluated symptomatic and asymptomatic legs in 17 subjects with unilateral PAD-IC and 16 without PAD-IC (control group), during walking. Tibialis anterior (TA) and gastrocnemius medialis (GM) electromyographic activity, and peaks of vertical ground reaction force were recorded in this prospective study. We analyzed the coactivation index (CI(GM/TA)) during three periods (pain-free, pain and maximum pain) and phases of the gait cycle. Statistical analysis was carried out using the ANOVA procedure. RESULTS: During single support, CI(GM/TA) increases in the symptomatic leg during the pain period (+28 %) and in the asymptomatic leg during the maximum pain period (+29 %). During second double support, CI(GM/TA) increases in the symptomatic leg only (+49 %). In these gait phases, pain elicits differences in CI(GM/TA) between legs (p < 0.05). Second peak force decreases in the symptomatic leg only (-9%) and is negatively correlated with CI(GM/TA) during the three periods (r = -0.57; -0.76 and -0.78 respectively, p < 0.05). No difference is found in the control group. SIGNIFICANCE: The appearance and development of pain in the lower limbs is associated with a higher level of CI(GM/TA), revealing a compensatory gait pattern in PAD-IC patients. Optimal prevention, rehabilitation and re-training strategies for PAD-IC patients should take into consideration neuromuscular compensatory mechanisms between asymptomatic and symptomatic legs.

Morphological changes in the long axis of the lower leg muscles during isometric contraction in the sitting position.

[Purpose] To compare the changes in the muscle cross-sectional area (MCSA) along the long axis of the lower leg muscles at rest and during ankle plantar flexors isometric contraction and to obtain basic information regarding the movement of lower leg muscles during ankle plantar flexors contraction. [Participants and Methods] Sixteen healthy young female participants (20.9 ± 1.2 years) were asked to sit with their ankles in a neutral ankle position. Images were obtained at rest and during isometric contraction of the ankle plantar flexors using gravity magnetic resonance imaging. The MCSAs of the triceps surae and tibialis anterior were measured. [Results] The middle region of the soleus muscle had a lower MCSA on contraction than at rest. In addition, the medial head of the gastrocnemius had a lower MCSA on contraction than at rest in the distal quarter. Moreover, the tibialis anterior had a lower MCSA at rest than on contraction in the middle region. [Conclusion] The area to be used as an indicator and the movement to be induced differ depending on the muscle during isometric contraction of the triceps surae.