AIMThe purpose of this experiment was to investigate the cardiac physiological characteristics for adaptation to high-altitude hypoxia in chickens.

METHODSTibetan, Dwarf Recessive White and Shouguang chickens were fed at low-and high-altitude, and measurements were made in heart weights, lactic acid (LA), lactate dehydrogenase (LDH), and succinate dehydrogenase (SDH) at the age of 10 weeks.

RESULTSThe results showed that Tibetan chickens at high-altitude had lower heart weight and LA content, and similar LDH activity, and higher SDH activity when compared to Dwarf Recessive White and Shouguang chickens.

CONCLUSIONIt was concluded that the cardiac mechanisms of high-altitude hypoxic adaptation in Tibetan chickens were increasing neither heart weight, nor level of anaerobic metabolism, but the higher SDH activity was significant to the adaptation. The SDH was a symbol enzyme for hypoxic adaptation in Tibetan chicken.

Adaptation, Physiological ; Altitude ; Animals ; Chickens ; physiology ; Heart ; physiology ; Hypoxia ; veterinary

Late embryogenesis abundant (LEA) proteins are well associated with the desiccation tolerance in organisms. LEA proteins are categorized into at least seven groups by virtue of similarities in their deduced amino acid sequences. Most of the LEA proteins have the characteristics of high hydrophilicity and thermo-stability. The LEA proteins are in unstructured conformation in aqueous solution. However, they adopted amphiphilic alpha-helix structure during desiccation condition. LEA proteins are localized to the different organelles in the cells, i.e. cytoplasm, endoplasmic reticulum, mitochondria and nucleus. The multi-functional capacity of LEA proteins are suggested, as protein stabilization, protection of enzyme activity, membrane association and stabilization, antioxidant function, metal-ion binding or DNA protection, etc. Here, we review the structural and functional characteristics of LEA proteins to provide a reference platform to understand their protective mechanisms during the adaptive response to desiccation in organisms.
Adaptation, Physiological ; Dehydration ; Desiccation ; Droughts ; Plant Physiological Phenomena ; Plant Proteins ; physiology ; Stress, Physiological

Adaptation, Physiological ; physiology ; Humans ; Hypothermia ; Physical Examination ; Transition Temperature ; Water

The polar sports tester made in Finland as one of the most widespread instruments in physical training is of importance for sports training. In this paper, we have developed a set of system for analysis of physical training workload using the measured data of the Polar Sports Tester, and have established a set of analysis indices and reports of the physical training workload, including five categories and 127 quantitative indices. It can reflect the distribution of physical workload and provide a series of parameters for coaches to direct scientific training and raise sport level.
Adaptation, Physiological ; physiology ; Gymnastics ; Humans ; Models, Biological ; Physical Endurance ; physiology ; Software ; Sports ; physiology

Weight-bearing bone is constantly adapting its structure and function to mechanical environments. Loading through routine exercises stimulates bone formation and prevents bone loss, but unloading through bed rest and cast immobilization as well as exposure to weightlessness during spaceflight reduces its mass and strength. In order to elucidate the mechanism underlying unloading-driven bone adaptation, ground-based in vitro and in vivo analyses have been conducted using rotating cell culturing and hindlimb suspension. Focusing on gene expression studies in osteoblasts and hindlimb suspension studies, this minireview introduces our recent understanding on bone homeostasis under weightlessness in space. Most of the existing data indicate that unloading has the opposite effects to loading through common signaling pathways. However, a question remains as to whether any pathway unique to unloading (and not to loading) may exist.
Adaptation, Physiological ; Animals ; Bone and Bones ; cytology ; physiology ; Hindlimb Suspension ; physiology ; Humans ; Osteoblasts ; physiology ; Weightlessness

AIMTo verify the hypothesis that repeated body position change training can improve human head-down tilt (HDT) tolerance.

METHODSSix young healthy subjects were trained with repeated position change for 9 times and 11 days according to protocol of alternative head-down and head-up tilts, each time of training lasted for about 35 min. Their HDT tolerance (- 30 degrees/30 min) were determined before and after training.

RESULTS(1) Compared with the data before training, subjects' symptom scores during HDT test after training decreased significantly (6.00 +/- 3.79 vs 1.00 +/- 0.63, P < 0.05), magnitude of the decreased heart rate increased significantly (-0.6 +/- 2.5 vs -4.4 +/- 3.6, P < 0.01). (2) Before training, blood flow volume of internal jugular vein (IJV) during HDT decreased significantly and that of internal carotid artery (ICA) increased significantly at the beginning period of HDT compared with pre-HDT (P < 0.01), while blood flow volume of the common carotid artery (CCA) presented increasing trend. After training, there was no significant difference in blood flow volume of IJV between during HDT and pre-HDT, that of ICA and CCA presented decreasing trend in the final period of HDT compared with Pre-HDT.

CONCLUSIONRepeated body position change training can improve human head-down tilt tolerance. And its main causation is that headward shift of blood volume is restrained to some extend during HDT after training.

Adaptation, Physiological ; physiology ; Adolescent ; Astronauts ; Cardiovascular Physiological Phenomena ; Head-Down Tilt ; Humans ; Male ; Posture ; physiology ; Weightlessness Simulation ; Young Adult

Long-term endurance training or physical activity has been confirmed not only to improve physical performance, but to bring about an obvious beneficial effect on human health; however, the mechanism of this effect is not clear. The most studied health adaptations in skeletal muscle response to endurance exercise are increased muscle glycogen level and insulin sensitivity, fiber type transformation toward oxidative myofibers, and increased mitochondrial content/function. Mitochondria are dynamic organelles in eukaryotic cells critical in physical performance and disease occurrence. The mitochondrial life cycle spans biogenesis, maintenance, and clearance. Exercise training may promote each of these processes and confer positive impacts on skeletal muscle contractile and metabolic functions. This review focused on the regulation of these processes by endurance exercise and discussed its potential benefits in health and disease. We presented evidence suggesting that exercise training potentiates not only the biogenesis of mitochondria but also the removal of old and unhealthy mitochondria through mitochondrial quality control.
Adaptation, Physiological ; Exercise ; Humans ; Mitochondria ; physiology ; Muscle Contraction ; Muscle, Skeletal ; physiology

In the long time of natural evolution, the bodies of some animals, such as feline, that live in the wild and complicate surroundings have evolved to possess outstanding buffering characteristics, which make the animals adapt to the environment perfectly. These animals generally have well-developed paw pads under their soles to play an important role in attenuating the intensity of impact when they land on the ground. Investigating the buffering characteristics of these animals' paw pads could help us to design "bionic" buffering and energy-absorption devices. In this paper, based on observations of animal jumping test, a simple mass-spring-buffer model was proposed to explore the buffering characteristics of the animals' paw pads. By analytically solving the differential equations of this model, the parameters concerned with paw pads functions were discussed and some significant results were obtained.
Adaptation, Physiological ; Animals ; Biomechanical Phenomena ; Felidae ; anatomy & histology ; physiology ; Foot ; anatomy & histology ; physiology ; Models, Theoretical

As human beings ascend to high altitude, a number of reactions may occur against hypoxic injuries. These hypoxic responses are related to intake, transportation and utility of the oxygen. As a crucial subcellular organelle of oxygen utility, mitochondrion is a central link of high altitude acclimatization, adaptation and mountain sicknesses. In this review, we discussed the recent advances in researches on hypoxic mitochondrial responses at high altitude.
Adaptation, Physiological ; Altitude ; Altitude Sickness ; Animals ; Humans ; Hypoxia ; Mitochondria ; pathology ; Oxygen ; physiology

Nowadays, for gait instability phenomenon, many researches have been carried out at home and abroad. However, the relationship between plantar pressure and gait parameters in the process of balance adjustment is still unclear. This study describes the human body adaptive balance reaction during slip events on slippery level walk by plantar pressure and gait analysis. Ten healthy male subjects walked on a level path wearing shoes with two contrastive contaminants (dry, oil). The study collected and analyzed the change rule of spatiotemporal parameters, plantar pressure parameters, vertical ground reaction force (VGRF), etc. The results showed that the human body adaptive balance reaction during slip events on slippery level walk mainly included lighter touch at the heel strikes, tighter grip at the toe offs, a lower velocity, a shorter stride length and longer support time. These changes are used to maintain or recover body balance. These results would be able to explore new ideas and provide reference value for slip injury prevention, walking rehabilitation training design, research and development of walking assistive equipments, etc.
Adaptation, Physiological ; Foot ; Gait ; Humans ; Male ; Postural Balance ; physiology ; Pressure ; Reference Values ; Walking