Mechanical work accounts for most of the energetic cost in human running

The metabolic cost of human running is not well explained, in part because the amount of work performed actively by muscles is largely unknown. Series elastic tissues such as tendon can save energy by performing work passively, but there are few direct measurements of the active versus passive contributions to work in running. There are, however, indirect biomechanical measures that can help estimate the relative contributions to overall metabolic cost. We developed a simple cost estimate for muscle work in humans running (N = 8) at moderate speeds (2.2–4.6 m/s) based on measured joint mechanics and passive dissipation from soft tissue deformations. We found that even if 50% of the work observed at the lower extremity joints is performed passively, active muscle work still accounts for 76% of the net energetic cost. Up to 24% of this cost compensates for the energy lost in soft tissue deformations. The estimated cost of active work may be adjusted based on assumptions of multi-articular energy transfer, elasticity, and muscle efficiency, but even conservative assumptions yield active work costs of at least 60%. Passive elasticity can reduce the active work of running, but muscle work still explains most of the overall energetic cost.

PERFECTION of PREPARATION TECHNOLOGY of the CATALYST CARRIER

Сибунит – носитель для катализатора, использующегося в различных процессах химической промышленности, в том числе и в реакции гидрирования. В настоящее время для его подготовки и проведения технологических операций используется так называемый «сухой» способ, обладающий обширными недостатками, основными из которых являются пыление, а также значительная доля ручного труда на производстве и, как следствие, большая продолжительность отдельных стадий.Предлагается использовать «мокрый» способ с применением аппаратуры роторно-пульсационного типа для подготовки носителя катализатора с целью исключения указанных недостатков.В результате проведённой работы было установлено, что активность образцов катализаторов, полученных с использованием молотковой мельницы и с применением роторно-пульсационного аппарата в реакции гидрогенолиза составила 0,606 моль/мин и 0,642 моль/мин, при выходе целевого продукта 76,15% и 80,00%, соответственно. Также определено, что доля потерь, обусловленная образованием пыли, была снижена более чем в 10 раз по сравнению с действующей технологией. Sibunit is carrying agent for the catalyst used in various processes of the chemical industry, including in hydrogenation reaction. Now for its preparation and conducting of technological operations the so-called "dry" way possessing extensive deficiencies is used, basic of which the fluffing, and also a considerable share of muscle work on manufacture and, as consequence, the big duration of separate stages are.It is offered to use a "wet" way with application of rotor-stator equipment for preparation of a catalyst carrier for the purpose of exclusion of the specified deficiencies.As a result of the spent work it has been established, that activity of the catalysts samples gained with use of the hammer mill and with application rotor-stator system in hydrogenation reaction has made 0,606 gramme-molecules/mines and 0,642 gramme-molecules/mines, at an yield of a target product of 76,15% and 80,00%, accordingly. Also it is defined, that the share of losses caused by a dust generation, it has been lowered more than in 10 times in comparison with acting technology.

Influence of a special training process on the psychomotor skills of cadet pilots

PurposeThe subject of this article is related to the work-activity in the air environment. The aim of the study was to check the effectiveness of the training process based on devices, which using require special biomechanical muscle work. In the research was check the influence of the training process on the Special Aviation Gymnastics Instruments (SAGI) on the improvement of the psychomotor skills, expressed as an increase in the percentage of ability to perform all tasks and the number of reels on a loop.MethodsCadets - second year pilots, studying at the faculty of a pilot. Cadets were carrying out a special pilot training program on SAGI. They were subjected to two exercise tests (reels forward on looping), before and after the period of special training. Exercise tests were performed with the use of a diagnostic and training device used to assess psychomotor skills. During two tests, heart rate (HR) and blood pressure were measured.ResultsThere was a statistically significant increase in the percentage of ability to perform all tasks (p<0.01) and a statistically insignificant increase in the number of reels forward on looping, in test II in relation to test I. In test II, a statistically insignificant higher level of heart rate and blood pressure before and after the effort was noted, compared to test I.ConclusionsIt was found that the training process on SAGI increased the psychomotority level by increasing the percentage of ability to perform all tasks and the number of reels, in test II in relation to test I.

A randomized placebo-controlled clinical trial of Nicotinamide Riboside and Pterostilbene supplementation in experimental muscle injury in elderly subjects

Background Maintenance and regeneration of functional skeletal muscle are dependent on a sufficient pool of muscle stem cells (MuSCs). During ageing there is a functional decline in this cellular pool which influences the regenerative capacity of skeletal muscle. Preclinical evidence have suggested that Nicotinamide Riboside (NR) and Pterostilbene (PT) can improve muscle regeneration e.g. by increasing MuSC function. The objective of the present study was to investigate if NRPT supplementation promotes skeletal muscle regeneration after muscle injury in elderly humans by improved recruitment of MuSCs. Methods In a randomized, double-blinded, placebo-controlled trial, 32 elderly men and women (55-80 yr) received daily supplementation with either NRPT (1000 mg NR + 200 mg PT) or matched placebo. Two weeks after initiation of supplementation, a skeletal muscle injury was applied in the vastus lateralis part of the quadriceps femoris muscle by electrically induced eccentric muscle work in a dynamometer. Skeletal muscle biopsies were obtained pre, 2h, 2, 8, and 30 days post injury. The main outcome of the study was change in MuSC content 8 days post injury. Results 31 enrolled subjects completed the entire protocol. The muscle work induced a substantial skeletal muscle injury in the study participants and was associated with release of myoglobin and creatine kinase, muscle soreness, tissue edema, and a decrease in muscle strength. MuSC content increased by 107% 8 days post injury (p= 0.0002) but with no effect of NRPT supplementation (p=0.58 for supplementation effect). MuSC proliferation and cell size revealed a large demand for recruitment post injury but was not affected by NRPT. Furthermore, histological analyses of muscle fiber area, internal nuclei and embryonic Myosin Heavy Chain showed no effect of NRPT supplementation. Conclusion Daily supplementation with 1000 mg NR + 200 mg PT is safe but does not improve recruitment of the MuSC pool or other measures of muscle recovery in response to injury or subsequent regeneration in elderly subjects.

Pemberian Terapi Senam Kaki Pada Pasien Diabetes Mellitus Di Desa Gunung Labuhan Sungkai Selatan Lampung Utara

ABSTRAK Data Riskesdas Provinsi Lampung tahun 2013 jumlah penderita diabetes mellitus yang terdiagnosis dokter sebesar 0,7%. Prevalensi penderita diabetes mellitus di Lampung utara berada di posisi kelima terbanyak dengan jumlah 0,8%. Sementara jumlah penderita di Lampung yang terdiagnosis dan yang tidak terdiagnosis tetapi selama sebulan terakhir mengalami gejala-gejala diabetes mellitus berjumlah lebih besar yaitu 0,8% dengan prevalensi di Lampung utara sebesar 0,8%. Penatalaksanaan diabetes mellitus terdiri dari 5 pilar utama olahraga atau latihan fisik merupakan salah satu dari penatalaksanaan tersebut selain dari diet, obat-obatan, edukasidan pemantauan, Olah raga dalam arti gerak fisik atau kerja otot dapat meningkatkan metabolisme atau pembentukan dan pengeluaran energi tubuh, salah satunya yaitu senam kaki. Tujuan setelah penyuluhan dan demonstrasi, diharapkan pemberian senam kaki dapat untuk menurunkan kadar glukosa pada klien diabetes melitus. Adapun kegiatan yang dilakukan berupa penyuluhan menggunakan leaflet dan demonstrasi senam kaki. Terdapat penurunan kadar glukosa pada klien diabetes melitus setelah pemberian akupresur selama 7 hari di Desa gunung labuhan sungkai selatan, Lampung Utara. Dengan demikian, pemberian senam kaki pada klien diabetes melitus sangat efektif dalam menurunkan glukosa. Kata Kunci: Senam kaki, diabetes melittus ABSTRACT Lampung Province Riskesdas data in 2013 the number of people with diabetes mellitus diagnosed by doctors (0.7%). The prevalence of people with diabetes mellitus in northern Lampung is in the fifth position (0.8%). While the number of sufferers in Lampung who were diagnosed and those who were undiagnosed, during the last month experiencing symptoms of diabetes mellitus was greater, namely (0.8%) with a prevalence in northern Lampung (0.8%). Management of diabetes mellitus consists of 5 main pillars of sports or physical exercise is one of these treatments apart from diet, drugs, education, and monitoring, Sports in the sense of physical movement or muscle work can increase metabolism or the formation and expenditure of the body's energy, one of which is foot exercise. The aim after counseling and demonstration is expected to provide foot exercises to reduce glucose levels in clients with diabetes mellitus. The activities were carried out in the form of counseling using leaflets and foot exercises. There was a decrease in glucose levels in diabetes mellitus clients after giving acupressure for 7 days in the village of Gunung Labuhan, South Sungkai, North Lampung. Thus, giving foot exercises to diabetes mellitus clients is very effective in reducing glucose. Keywords: Foot exercises, diabetes Mellitus

Muscle Actuators, Not Springs, Drive Maximal Effort Human Locomotor Performance

The current investigation examined muscle-tendon unit kinematics and kinetics in human participants asked to perform a hopping task for maximal performance with variational preceding milieu. Twenty-four participants were allocated post-data collection into those participants with an average hop height of higher (HH) or lower (LH) than 0.1 m. Participants were placed on a customized sled at a 20º angle while standing on a force plate. Participants used their dominant ankle for all testing and their knee was immobilized and thus all movement involved only the ankle joint and corresponding propulsive unit (triceps surae muscle complex). Participants were asked to perform a maximal effort during a single dynamic countermovement hop (CMH) and drop hops from 10 cm (DH10) and 50 cm (DH50). Three-dimensional motion analysis was performed by utilizing an infrared camera VICON motion analysis system and a corresponding force plate. An ultrasound probe was placed on the triceps surae muscle complex for muscle fascicle imaging. HH hopped significantly higher in all hopping tasks in comparison to LH. In addition, the HH group concentric ankle work was significantly higher in comparison to LH during all of the hopping tasks. Active muscle work was significantly higher in HH in comparison to LH as well. Tendon work was not significantly different between HH and LH. Active muscle work was significantly correlated with hopping height (r = 0.97) across both groups and hopping tasks and contributed more than 50% of the total work. The data indicates that humans primarily use a motor-driven system and thus it is concluded that muscle actuators and not springs maximize performance in hopping locomotor tasks in humans.

Muscle-specific economy of force generation and efficiency of work production during human running

Human running features a spring-like interaction of body and ground, enabled by elastic tendons that store mechanical energy and facilitate muscle operating conditions to minimize the metabolic cost. By experimentally assessing the operating conditions of two important muscles for running, the soleus and vastus lateralis, we investigated physiological mechanisms of muscle work production and muscle force generation. We found that the soleus continuously shortened throughout the stance phase, operating as work generator under conditions that are considered optimal for work production: high force-length potential and high enthalpy efficiency. The vastus lateralis promoted tendon energy storage and contracted nearly isometrically close to optimal length, resulting in a high force-length-velocity potential beneficial for economical force generation. The favorable operating conditions of both muscles were a result of an effective length and velocity-decoupling of fascicles and muscle-tendon unit, mostly due to tendon compliance and, in the soleus, marginally by fascicle rotation.

Muscle Work and Its Relationship with ACE and ACTN3 Polymorphisms Are Associated with the Improvement of Explosive Strength

Background: The potential influence of genetics in athletic performance allows the search for genetic profiles associated with muscular work for the orientation of strength training and sports selection. The purpose of the study was to analyze four muscular exercises for effectiveness in improving explosive strength variables, associated to the genetics in Angiotensin Converting Enzyme (ACE) and α-actinin-3 (ACTN3) polymorphisms. Methods: A randomized controlled trial was conducted on a sample of 80 subjects allocated into four groups: concentric muscle work (CMW), eccentric muscle work (EMW), concentric-eccentric muscle (C-EMW) work and isometric muscular work (IMW), by block and gender randomization. Vertical jump, long jump, power jump, and speed were measured to study explosive strength. Genotypic frequencies of ACE (rs4646994) and ACTN3 (rs1815739) were obtained by polymerase chain reaction. Results: ACE gen showed significant improvements regarding the DD genotype in the Sargent test (p = 0.003) and sprint velocity test (p = 0.017). In the ACTN3 gene, the RR variable obtained improvement results with regard to RX and XX variables in long jump (p < 0.001), Sargent test (p < 0.001) and power jump (p = 0.004). Conclusions: The selected genes demonstrated an influence on the muscle work and the improvement in explosive strength variables with a decisive role regarding the type of muscle work performed.