Physical factors for health include cardiorespiratory fitness (CRF), muscle fitness/endurance, body composition, and flexibility. Many epidemiological studies have reported the relationship between CRF and health. A representative cohort study regarding CRF, the Aerobics Center Longitudinal Study was published. Also, cohort studies involving Japanese people, the Tokyo Gas Study, Juntendo University alumni study, and Japan Epidemiology Collaboration on Occupational Health study have been presented. Most of these studies indicated that all-cause mortality and cancer mortality were low in persons in whom high-level CRF was maintained, and that the incidences of hypertension and diabetes were low in these persons as well. These results suggest that premature death and some lifestyle-related diseases can be prevented by maintaining a high-level of CRF, that is, by continuously performing active physical activity.
Recently, many people are using insoles. They are used for structural and positional imbalance such as foot deformities. However, evidence of their effect remains unclear. The aim of this review is to investigate the scientific evidence on the effect of various insoles. A comprehensive review of the English-language scientific literature was carried out covering the period from April 1980 to January 2013 of MEDLINE, CINAHL and EMBASE databases, to search for articles relating to insoles for the prevention and treatment of lower extremity injuries. When data were available for stratification, we extracted information concerning patients with knee osteoarthritis (15 studies), Diabetes mellitus (3 studies) and other diseases (12 studies), comparisons of different insoles (10 studies), and sports injuries (6 studies). An improvement effect on alignment was found in femorotibial alignment; and it was suggested that such alignment is effective for knee osteoarthritis (OA). The insole has an effect on preventing the progression of the transformation of the foot part of patients with diabetes; and, as a result, it is thought of as an effective therapy for patients with diabetes. This review provides evidence for the beneficial effect of insoles in the treatment of some musculoskeletal disorders. However, some trials were compromised by poor methodology. Likewise, it is necessary to determine the effect of shoes, in addition to insoles, and to investigate their effect in the future.
Iron is a nutrient and its deficiency is the most frequent nutritional disorder worldwide, occurring in 4 to 5 billion people corresponding to about 70-80% of the world’s population as estimated by the World Health Organization. However, an excess of iron increases oxidative stress and increases the risk of death and cancer; thus blood transfusion and supplementation should be used with caution. As there is no mechanism for deliberate iron excretion, the regulation of iron absorption in the small intestine is required to maintain total body iron balance and prevent excessive or deficient iron levels. Proteins involved in intestinal iron absorption were first identified in 1997. Molecular mechanisms of iron transport from the lumen of the small intestine to the portal blood through epithelial cells have been elucidated. In addition to long responses to iron deficiency in vivo, a short response exists for iron concentrations in the small intestine. This review describes regulatory mechanisms at the forefront of iron absorption, focusing on short acting mucosal block.
Exercising muscle blood flow (BF) may be an indicator of oxygen supply change allowing increased muscle energy metabolism through the circulatory response between central and peripheral hemodynamics. During exercise an increase in cardiac output may represent the interplay of alterations in both blood pressure and vascular conductance. Dynamic muscle contractions lead to an increase in cardiac output and promote venous return at the onset of exercise, and concurrently lead to enhanced muscle vasodilatation (and thus increased muscle BF) due to metabolites, neurological responses and/or other mechanisms, causing exercise hyperaemia. Doppler ultrasound can non-invasively detect with high resolution the temporal pulsatile blood velocity profiles in the conduit artery at rest as well as during muscle contractions. Based on this technique, it has been shown that alterations in the physiological blood velocity profile related to cardiac systole-diastole and fluctuations in the beat-by-beat blood velocity profile are due to rapid changes in the blood velocity profile concurrent with muscle contraction and/or relaxation during exercise (dynamic/static) or respiratory cycle, in different states (muscle contraction time/frequency or workload), or of any other type of vasodilatation/vasoconstriction. Muscle contraction-induced alterations in the blood velocity profile may be due in general to the magnitude of intramuscular pressure variation (mechanical factors) and the superimposed influence of perfusion pressure variation (pulsatile hemodynamic factors). This review therefore focuses on methodological considerations for muscle contraction-induced blood velocity/flow variability in the leg conduit artery, which in turn influences the magnitude of exercising BF during dynamic knee extensor exercise.
Exercise is known to affect glucose metabolism in healthy and diabetic individuals. Recent studies have demonstrated that both acute and chronic exercise improve glucose metabolism via several mechanisms. Acute exercise increases glucose uptake through activation of AMP-activated protein kinase with an increase in the intracellular AMP/ATP ratio, and also increases insulin sensitivity, possibly through TBC1 domain family member 4 regulation in the post-exercise period. Exercise also affects other organs in addition to skeletal muscle. Chronic exercise affects insulin secretion from the pancreas in response to glucose stimulation. This review describes how acute or chronic exercise regulates glucose metabolism. Although the detailed mechanisms remain unclear, these pathways might explain why exercise improves whole-body glucose metabolism.
Physical activity of moderate intensity, like walking and jogging, can reduce the risk of developing metabolic syndrome and improve hypertension. However, such anti-hypertensive effects have yet to be fully studied. To explore the mechanisms underlying exercise-induced hypotensive effects, normotensive or hypertensive rats were subjected to voluntary wheel-running exercise. In consequence, daily wheel-running exercise appears to decrease resting blood pressure by multiple mechanisms. This short review focuses on possible mechanisms underlying the hypotensive effects of wheel-running exercise, i.e., hormonal control, nitric oxide control, sympathetic nervous control and central control in resting blood pressure regulation. To conclude, a voluntary wheel-running exercise-induced reduction in resting blood pressure may be accomplished via multiple mechanisms, i.e., a combination of 1) attenuated vasoconstriction by hormones, 2) hormone-induced reduction in blood volume, 3) hormone- and/or NO-induced vasodilation, and 4) diminished sympathetic nervous activity by body weight loss / less body weight gain, lower leptin levels and/or downregulation of serotonine 1A receptor gene in the nucleus tractus solitarii.
A number of changes occur with aging in skeletal muscles including a reduction in muscle fiber size and fiber number. However, recent studies have indicated that the elderly tend to be more resistant to fatigue than the young, particularly during prolonged isometric muscle contraction. In this review, we explore the molecular mechanisms in muscle cells that are involved in this phenomenon. Aging has been thought to induce preferential loss of fast-type fibers. However, previous studies have shown that a fiber-type shift with aging is specific to the region, type and/or function of the muscles. Aging promotes the production of reactive oxygen species (ROS) in skeletal muscle, and ROS is suggested to activate AMP-activated protein kinase (AMPK). AMPK signaling is involved in muscle atrophy, and it activates peroxisome proliferator-activated receptor gamma coactivator 1-alpha (PGC-1α). PGC-1α is considered a key regulator of mitochondrial biogenesis, and furthermore, it could be involved in the reinnervation of muscle fibers that have been denervated due to aging. Thus, the balance between AMPK and PGC-1α could play an important role in increasing fatigue resistance in aged skeletal muscle.
This short review discusses the development of respiratory function and pulmonary ventilation during exercise in children. Children have a lower lung capacity than adults because of their smaller chest and relatively narrow airways. Respiratory muscle strength (RMS), which is evaluated by maximal expiratory (PEmax) and maximal inspiratory (PImax) mouth pressure, is also lower in children than adults. RMS tends to be higher among children who exercise, in particular, in those who swim. Minute pulmonary ventilation during exercise is lower in children, whereas respiratory frequency and tidal volume to vital capacity are higher, suggesting that exercising children have lower ventilatory efficiency and higher ventilatory effort than adults. Thus, expiratory flow limitation (expFL) caused by mechanical constraints, observed in adult females with small chest walls and in endurance athletes with high ventilatory demands, is also observed in most children. Although expFL limits hyperventilation and leads to exercise-induced arterial hypoxemia (EIAH) in adults, only a third of children show EIAH. Physically trained children with high maximal oxygen uptake tend to have a greater expFL, which could be one of the mechanisms responsible for EIAH.
The neurotransmitter serotonin (5-hydroxytryptamine, 5-HT) is involved in the regulation of several basic physiological functions such as hormone secretion, sleep-wake cycle, motor control, immune system functioning, nociception, food intake, energy balance and thermoregulation. In addition, 5-HT participates in higher brain functions, such as cognition and emotional states, by modulating synaptic plasticity and neurogenesis. Furthermore, 5-HT has recently captured the spotlight in connection with depression, synthetic narcotic drugs, hot flash, central fatigue, etc. Regarding thermoregulation, many studies have examined the relationship between 5-HT and body temperature (Tb) regulation since the 1960s. Feldberg and Myers, in pioneering experiments, first reported that microinjection of 5-HT into the cerebral ventricles or hypothalamus induced a rise in Tb. Subsequently, research on 5-HT and regulation of Tb continued and topics in recent years include resolving of 5-HT receptor subtypes, such as 5-HT1A, 5-HT3, 5-HT7, and pinpointing a local area or network for thermoregulation. In this short review, I first outline the serotonergic system in the brain, summarize the history of research on 5-HT and thermoregulation, and finally focus on recent research in the 21st century.
We examined the muscle glycogen, and muscle and plasma lactate concentrations before and after 1 and 2 min of intensive exercise at 120% VO2max, and examined possible relationships between these indexes and protein levels of monocarboxylate transporters (MCT) in the gluteus medius muscle of Thoroughbred horses. The horses underwent 1 and 2 min of intensive exercise at the speed of 120% maximal oxygen consumption (VO2max) on a treadmill. The plasma lactate concentration increased after 1-min exercise (11.7 ± 0.8 mmol/L) and 2-min exercise (23.1 ± 1.1 mmol/L). The muscle lactate concentration increased after 1-min exercise (17.3 ± 2.1 mmol/kg) and 2-min exercise (23.6 ± 2.0 mmol/kg). While there was no significant difference in lactate accumulation in the plasma between the first minute and the second minute, lactate accumulation in muscle significantly decreased in the second minute compared with the first minute. The muscle glycogen level decreased after both 1- (42%) and 2-min (41%) exercise, but there was no difference between the levels after 1- and 2-min exercise. The muscle lactate concentration after 2-min intensive exercise positively correlated with the protein level of MCT4 (r = 0.78, p < 0.01). These results suggest that glycogen breakdown occurs in the first minute of intensive exercise, and Thoroughbred horses with higher muscle lactate production during exercise are endowed with higher expression of MCT4, that facilitates the efflux of lactate from muscle cells.
We investigated differences in trunk rotation patterns during baseball batting in eight skilled (collegiate level) players and nine unskilled novices using high-speed video cameras. The maximum angle during the backswing, angle at bat-ball impact, and angular displacement during the forward swing were analyzed for data on upper torso, pelvis, and torso-pelvis interaction (trunk twist) angles. We also noted movement variability in these angles over 10 trials, which was calculated as the standard deviation. The timing of the maximum angle during the backswing and variability was also analyzed. Statistical analysis revealed that angular displacements in the upper torso, pelvis, and torso-pelvis interaction were significantly larger in skilled players than in unskilled novices (p < 0.001, p < 0.001, and p < 0.05, respectively). The timing of the maximum pelvis angle during the backswing was significantly later in skilled players than in unskilled novices (p < 0.05). Movement variability in angular displacement during the forward swing and timing during the backswing were significantly greater in unskilled novices than skilled players. Although many previous studies reported the importance of angular velocity in trunk rotation during baseball batting, our results indicate that angular displacement and movement variability during trunk rotation are also key components for understanding the proficiency of skilled baseball players and unskilled novices.