Effects of resistance training on heat shock response (HSR), HSP70 expression, oxidative stress, inflammation, and metabolism in middle-aged people.

Resistance training (RT) can increase the heat shock response (HSR) in the elderly. As middle-aged subjects already suffer physiological declines related to aging, it is hypothesized that RT may increase the HSR in these people. To assess the effects of resistance training on heat shock response, intra and extracellular HSP70, oxidative stress, inflammation, body composition, and metabolism in middle-aged subjects. Sixteen volunteers (40 - 59 years) were allocated to two groups: the trained group (n = 7), which performed 12 weeks of RT; and the physically inactive-control group (n = 9), which did not perform any type of exercise. The RT program consisted of 9 whole-body exercises (using standard gym equipment) and functional exercises, carried out 3 times/week. Before and after the intervention, body composition, muscle mass, strength, functional capacity, and blood sample measurements (lipid profile, glucose, insulin, oxidative damage, TNF-α, the HSR, HSP70 expression in leukocytes, and HSP72 in plasma) were performed. The HSR analysis demonstrated that this response is maintained at normal levels in middle-aged people and that RT did not cause any improvement. Also, RT increases muscle mass, strength, and functional capacity. Despite no additional changes of RT on the antioxidant defenses (catalase, glutathione peroxidase, and reductase) or inflammation, lipid peroxidation was diminished by RT (group x time interaction, p = 0.009), indicating that other antioxidant defenses may be improved after RT. HSR is preserved in middle-aged subjects without metabolic complications. In addition, RT reduces lipid peroxidation and can retard muscle mass and strength loss related to the aging process.

Influence of body composition and cardiorespiratory fitness on plasma HSP72, norepinephrine, insulin, and glucose responses to an acute aerobic exercise bout performed in the fed state.

Being overweight is already considered a metabolic risk factor, which can be overcome by increasing cardiorespiratory fitness (CRF). Acute exercise is known to induce changes in plasma hormones and heat shock proteins release. However, there is a lack of studies investigating the impact of body composition and CRF on these variables following acute aerobic exercise. To assess the influence of body composition and cardiorespiratory fitness on plasma heat shock protein 72 kDa (HSP72), norepinephrine (NE), insulin, and glucose responses to an acute aerobic exercise bout in the fed state. Twenty-four healthy male adults were recruited and allocated into three groups: overweight sedentary (n = 8), normal weight sedentary (n = 8), and normal weight active (n = 8). The volunteers performed an acute moderate exercise session on a treadmill at 70% of VO2 peak. Blood samples were drawn at baseline, immediately post-exercise, and at 1-h post-exercise. The exercise session did not induce changes in HSP72 nor NE but changes in glucose and insulin were affected by body mass index. Also, subjects with elevated CRF maintain reduced NE through exercise. At baseline, the overweight sedentary group showed elevated NE, insulin, and glucose; these last two impacting the HOMA-IR index. Thirty minutes of aerobic exercise at 70% VO2 peak, in the fed state, did not change the levels of plasma NE and HSP72. Elevated body composition seems to impact metabolic profile and increase sympathetic activity. Conversely, subjects with increased cardiorespiratory fitness seem to have attenuated sympathetic activity.

Acute effects of a single moderate-intensity exercise bout performed in fast or fed states on cell metabolism and signaling: Comparison between lean and obese rats.

AIMS: Although the benefits of exercise can be potentiated by fasting in healthy subjects, few studies evaluated the effects of this intervention on the metabolism of obese subjects. This study investigated the immediate effects of a single moderate-intensity exercise bout performed in fast or fed states on the metabolism of gastrocnemius and soleus of lean and obese rats. MAIN METHODS: Male rats received a high-fat diet (HFD) for twelve weeks to induce obesity or were fed standard diet (SD). After this period, the animals were subdivided in groups: fed and rest (FER), fed and exercise (30 min treadmill, FEE), 8 h fasted and rest (FAR) and fasted and exercise (FAE). Muscle samples were used to investigate the oxidative capacity and gene expression of AMPK, PGC1α, SIRT1, HSF1 and HSP70. KEY FINDINGS: In relation to lean animals, obese animals' gastrocnemius glycogen decreased 60 %, triglycerides increased 31 %; glucose and alanine oxidation decreased 26 % and 38 %, respectively; in soleus, triglycerides reduced 46 % and glucose oxidation decreased 37 %. Exercise and fasting induced different effects in glycolytic and oxidative muscles of obese rats. In soleus, fasting exercise spared glycogen and increased palmitate oxidation, while in gastrocnemius, glucose oxidation increased. In obese animals' gastrocnemius, AMPK expression decreased 29 % and SIRT1 increased 28 % in relation to lean. The AMPK response was more sensitive to exercise and fasting in lean than obese rats. SIGNIFICANCE: Exercise and fasting induced different effects on the metabolism of glycolytic and oxidative muscles of obese rats that can promote health benefits in these animals.

Heat-induced extracellular HSP72 release is blunted in elderly diabetic people compared with healthy middle-aged and older adults, but it is partially restored by resistance training.

Recent evidence suggests that the anti-inflammatory heat shock response (HSR) is reduced in aging and diabetes. In this study we compared HSR between healthy middle-aged adults, healthy elderly and type 2 diabetic (T2DM) elderly, and tested whether resistance training (RT) could improve the HSR in T2DM group. Thirty sedentary participants volunteered for this study. HSR (assessed as the capacity to export HSP72 during heat stress) was measured in the blood and compared between the groups. HSR was similar between healthy middle-aged and healthy elderly volunteers, but diminished in elderly T2DM (p < 0.001). Hence, T2DM subjects (n = 12) were submitted to a 12-week RT program, because exercise is a physiological HSR inducer. HSR, cytokines, metabolic parameters and visceral adipose tissue (VAT) were measured before and after the RT. Remarkably, VAT was negatively correlated with HSR (r = - 0.49, p < 0.01) while RT improved the HSR and reduced inflammation [TNF-α: from 51.5 ±â€¯9 to 40.7 ±â€¯4 pg/mL and TNF-α/IL-10 ratio: from 1.55 ±â€¯0.3 to 1.16 ±â€¯0.2 (p < 0.001)], without affecting other parameters. All together, these findings confirm the hypothesis that the anti-inflammatory HSR is depressed in elderly diabetic people, but can be partially restored by RT.

Circadian rhythms as a basis for work organization: a study with live line electricians.

OBJECTIVE: With the assumption that circadian rhythms influence human performance, the work of live line electricians was reorganized and evaluated. The hypothesis was that in highly physical and attention-demanding work, the organization of tasks, according to the ideal period of day and day of week, should diminish stress and consequent work risks. BACKGROUND: There are only a few studies reporting the work of electricians and even fewer approaching work organization. Moreover, these investigations often do not consider human physiological limitations and capabilities as well as task demands. METHOD: A new work system was proposed with consideration of (a) the circadian cycles and homeostatic processes; (b) the effect of heat, which is a zeitgeber (synchronizer) for the biological clocks; and (c) the degree of physical and mental demands of the different performed tasks, which was assessed on the basis of opinions of the electricians and physiological markers of stress that are controlled by circadian rhythms. The traditional and new systems were compared on the basis of two cognitive indices (the arrangement of matchsticks and the perception of a minute) and three physiological markers of mental-to-physical loads (heart frequency and the level of adrenaline and noradrenaline). RESULTS: Both physical and mental loads were reduced in the new system. CONCLUSION: Work organization should include consideration of human circadian rhythms, mainly when stressful and high-risk tasks are involved. APPLICATION: The findings can be applied in any work design, but they are especially suited for highly demanding work carried out outdoors.