981 resultados para exercise physiology


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Exercise has reported benefits for those with dementia. In the current study we investigated the feasibility of delivery and the physical and functional benefits of an innovative aquatic exercise program for adults with moderate to severe dementia living in a nursing home aged care facility. Ten adults (88.4 years, inter quartile range 12.3) participated twice weekly for 12 weeks. Anthropometric and grip strength data, and measures of physical function and balance were collected at baseline and post-intervention. Feasibility was assessed by attendance, participation, enjoyment and recruitment. Following exercise, participant's left hand grip strength had improved significantly (p = .017). Small to moderate effect sizes were observed for other measures. A number of delivery challenges emerged, but participant enjoyment, benefits and attendance suggest feasibility. Aquatic exercise shows promise as an intervention among those with dementia who live in a nursing home aged care facility. Greater program investigation is warranted.

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Purpose: Skin temperature assessment has historically been undertaken with conductive devices affixed to the skin. With the development of technology, infrared devices are increasingly utilised in the measurement of skin temperature. Therefore, our purpose was to evaluate the agreement between four skin temperature devices at rest, during exercise in the heat, and recovery. Methods: Mean skin temperature (T̅sk) was assessed in thirty healthy males during 30 min rest (24.0± 1.2°C, 56 ± 8%), 30 min cycle in the heat (38.0 ± 0.5°C, 41 ± 2%), and 45 min recovery(24.0 ± 1.3°C, 56 ± 9%). T̅sk was assessed at four sites using two conductive devices(thermistors, iButtons) and two infrared devices (infrared thermometer, infrared camera). Results: Bland–Altman plots demonstrated mean bias ± limits of agreement between the thermistors and iButtons as follows (rest, exercise, recovery): -0.01 ± 0.04, 0.26 ± 0.85, -0.37 ± 0.98°C; thermistors and infrared thermometer: 0.34 ± 0.44, -0.44 ± 1.23, -1.04 ± 1.75°C; thermistors and infrared camera (rest, recovery): 0.83 ± 0.77, 1.88 ± 1.87°C. Pairwise comparisons of T̅sk found significant differences (p < 0.05) between thermistors and both infrared devices during resting conditions, and significant differences between the thermistors and all other devices tested during exercise in the heat and recovery. Conclusions: These results indicate poor agreement between conductive and infrared devices at rest, during exercise in the heat, and subsequent recovery. Infrared devices may not be suitable for monitoring T̅sk in the presence of, or following, metabolic and environmental induced heat stress.

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Background: Individuals who fear falling may restrict themselves from performing certain activities and may increase their risk of falling. Such fear, reflected in the form of falls efficacy, has been measured in only a small number of studies measuring the effectiveness of exercise interventions in the elderly. This may be due to the various types of exercise that can be performed. Hence the effectiveness of exercise on falls efficacy is relatively understudied. Therefore, there is a need to measure falls efficacy as an outcome variable when conducting exercise interventions in the elderly. Methods: A total of 43 elderly community-dwelling volunteers were recruited and randomly allocated to a conventional exercise intervention, a holistic exercise intervention, or a control group. The interventions were performed 2 days per week for 10 weeks. Falls efficacy was measured at baseline and at the completion of the interventions using the Modified Falls Efficacy Scale (MFES). Results: Within group comparisons between baseline and follow-up indicated no significant improvements in falls efficacy, however, the difference for the conventional exercise group approached statistical significance (baseline 8.9 to follow-up 9.3; P = 0.058). Within group comparisons of mean difference MFES scores showed a significant difference between the conventional exercise group and the control group (conventional exercise group 0.4 vs control group −0.6; P < 0.05). Conclusion: Given the lack of significant improvements in falls efficacy found for any of the groups, it cannot be concluded whether a conventional or a holistic exercise intervention is the best approach for improving falls efficacy. It is possible that the characteristics of the exercise interventions including specificity, intensity, frequency and duration need to be manipulated if the purpose is to bring about improvements in falls efficacy.

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Enhancement of bone mineral acquisition during growth may be a useful preventive strategy against osteoporosis. The aim of this study was to explore the lean mass, strength, and bone mineral response to a 10-month, high-impact, strength-building exercise program in 71 premenarcheal girls, aged 9–10 years. Lean body mass, total body (TB), lumbar spine (LS), proximal femur (PF), and femoral neck (FN) bone mineral were measured using the Hologic QDR 2000+ bone densitometer. Strength was assessed using a grip dynamometer and the Cybex isokinetic dynamometer (Cybex II). At baseline, no significant difference in body composition, pubertal development, calcium intake, physical activity, strength, or bone mineral existed between groups. At completion, there were again no differences in height, total body mass, pubertal development, calcium intake, or external physical activity. In contrast, the exercise group gained significantly more lean mass, less body fat content, greater shoulder, knee and grip strength, and greater TB, LS, PF, and FN BMD (exercise: TB 3.5%, LS 4.8%, PF 4.5%, and FN 12.0%) compared with the controls (controls: TB 1.2%, LS 1.2%, PF 1.3%, and FN 1.7%). TB bone mineral content (BMC), LS BMC, PF BMC, FN BMC, LS bone mineral apparent density (BMAD), and FN bone area also increased at a significantly greater rate in the exercise group compared with the controls. In multiple regression analysis, change in lean mass was the primary determinant of TB, FN, PF, and LS BMD accrual. Although a large proportion of bone mineral accrual in the premenarcheal skeleton was related to growth, an osteogenic effect was associated with exercise. These results suggest that high-impact, strength building exercise is beneficial for premenarcheal strength, lean mass gains, and bone mineral acquisition.

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Background Cancer and its treatments produce lingering side-effects that undermine the quality of life (QOL) of survivors. Exercise and psycho-therapies increase QOL among survivors, however, research is needed to identify intervention characteristics most associated with such improvements. Objective This research aimed to assess the feasibility of a 9 week individual or group based exercise and counselling program, and to examine if a group based intervention is as effective at improving the QOL of breast cancer survivors as an individual-based intervention. Methods A three group design was implemented to compare the efficacy of a 9 week individual (IEC n = 12) and group based exercise and counselling (GEC n = 14) intervention to a usual care (UsC n = 10) group on QOL of thirty-six breast cancer survivors. Results Across all groups, 90% of participants completed the interventions, with no adverse effects documented. At the completion of the intervention, there was a significant difference between groups for change in global QOL across time (p < 0.023), with IEC improving significantly more (15.0 points) than the UsC group (1.8 points). The effect size was moderate (0.70). Although the GEC improved QOL by almost 10.0 points, this increase did not reach significance. Both increases were above the minimally important difference of 7–8 points. Conclusion These preliminary results suggest a combined exercise and psychological counseling program is both a feasible and acceptable intervention for breast cancer survivors. Whilst both the individual and group interventions improved QOL above the clinically important difference, only the individual based intervention was significant when compared to UsC.

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Purpose/Objectives: To examine peak volume of oxygen consumption (VO2peak) changes after a high- or low-intensity exercise intervention.
 Design: Experimental trial comparing two randomized intervention groups with control. 
 Setting: An exercise clinic at a university in Australia.
 Sample: 87 prostate cancer survivors (aged 47–80 years) and 72 breast cancer survivors (aged 34–76 years).
 Methods: Participants enrolled in an eight-week exercise intervention (n = 84) or control (n = 75) group. Intervention participants were randomized to low-intensity (n = 44, 60%–65% VO2peak, 50%–65% of one repetition maximum [1RM]) or high-intensity (n = 40, 75%–80% VO2peak, 65%–80% 1RM) exercise groups. Participants in the control group continued usual routines. All participants were assessed at weeks 1 and 10. The intervention groups were reassessed four months postintervention for sustainability. 
 Main Research Variables: VO2peak and self-reported physical activity.
 Findings: Intervention groups improved VO2peak similarly (p = 0.083), and both more than controls (p < 0.001). The high-intensity group maintained VO2peak at follow-up, whereas the low-intensity group regressed (p = 0.021). The low-intensity group minimally changed from baseline to follow-up by 0.5 ml/kg per minute, whereas the high-intensity group significantly improved by 2.2 ml/kg per minute (p = 0.01). Intervention groups always reported similar physical activity levels. 
 Conclusions: Higher-intensity exercise provided more sustainable cardiorespiratory benefits than lower-intensity exercise.
 Implications for Nursing: Survivors need guidance on exercise intensity, because a high volume of low-intensity exercise may not provide sustained health benefits.

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Objective: The aim of this study was to determine the feasibility of a combined supervised and home-based exercise intervention during chemotherapy for women with recurrent ovarian cancer. Secondary aims were to determine the impact of physical activity on physical and psychological outcomes and on chemotherapy completion rates. Methods: Women with recurrent ovarian cancer were recruited from 3 oncology outpatient clinics in Sydney and Canberra, Australia. All participants received an individualized exercise program that consisted of 90 minutes or more of low to moderate aerobic, resistance, core stability, and balance exercise per week, for 12 weeks. Feasibility was determined by recruitment rate, retention rate, intervention adherence, and adverse events. Aerobic capacity, muscular strength, fatigue, sleep quality, quality of life, depression, and chemotherapy completion rates were assessed at weeks 0, 12, and 24. Results: Thirty participants were recruited (recruitment rate, 63%), with a retention rate of 70%. Participants averaged 196 ± 138 min · wk of low to moderate physical activity throughout the intervention, with adherence to the program at 81%. There were no adverse events resulting from the exercise intervention. Participants who completed the study displayed significant improvements in quality of life (P = 0.017), fatigue (P = 0.004), mental health (P = 0.007), muscular strength (P = 0.001), and balance (P = 0.003) after the intervention. Participants completing the intervention had a higher relative dose intensity than noncompleters (P = 0.03). Conclusions: A program consisting of low to moderate exercise of 90 min · wk was achieved by two-thirds of women with recurrent ovarian cancer in this study, with no adverse events reported. Randomized control studies are required to confirm the benefits of exercise reported in this study.

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Hormesis enco 16 mpasses the notion that low levels of stress stimulate or upregulate 17 existing cellular and molecular pathways that improve the capacity of cells and organisms to 18 withstand greater stress. This notion underlies much of what we know about how exercise 19 conditions the body and induces long-term adaptations. During exercise, the body is 20 exposed to various forms of stress, including thermal, metabolic, hypoxic, oxidative, and 21 mechanical stress. These stressors activate biochemical messengers, which in turn activate 22 various signaling pathways that regulate gene expression and adaptive responses. 23 Historically, antioxidant supplements, nonsteroidal anti-inflammatory drugs, and 24 cryotherapy have been favored to attenuate or counteract exercise-induced oxidative stress 25 and inflammation. However, reactive oxygen species and inflammatory mediators are key 26 signaling molecules in muscle, and such strategies may mitigate adaptations to exercise. 27 Conversely, withholding dietary carbohydrate and restricting muscle blood flow during 28 exercise may augment adaptations to exercise. In this review article, we combine, integrate, 29 and apply knowledge about the fundamental mechanisms of exercise adaptation. We also 30 critically evaluate the rationale for using interventions that target these mechanisms under 31 the overarching concept of hormesis. There is currently insufficient evidence to establish 32 whether these treatments exert dose-dependent effects on muscle adaptation. However, 33 there appears to be some dissociation between the biochemical/molecular effects and 34 functional/performance outcomes of some of these treatments. Although several of these 35 treatments influence common kinases, transcription factors and proteins, it remains to be 36 determined if these interventions complement or negate each other, and whether such 37 effects are strong enough to influence adaptations to exercise.

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Increased concentrations of biomarkers reflecting myocardial stress such as cardiac troponin I and T and brain natriuretic peptide (BNP) have been observed following strenuous, long-lasting endurance exercise. The pathophysiological mechanisms are still not fully elucidated and the interpretations of increased post-exercise concentrations range from (i) evidence for exercise-induced myocardial damage to (ii) non-relevant spurious troponin elevations, presumably caused by assay imprecision or heterophilic antibodies. Several lines of evidence suggest that inflammatory processes or oxidative stress could be involved in the rise of NT-proBNP and Troponin observed in critically ill patients with sepsis or burn injury. We tested the hypothesis that inflammatory or oxidative stress is also responsible for exercise-induced cardiomyocyte strain in a large cohort of triathletes following an Ironman triathlon. However, the post-race increase in cardiac troponin T and NT-proBNP was not associated with several markers of exercise-induced inflammation, oxidative stress or antioxidant vitamins. Therefore, we clearly need more studies with other inflammatory markers and different designs to elucidate the scientific background for increases in myocardial stress markers following strenuous endurance events.

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Both a systemic inflammatory response as well as DNA damage has been observed following exhaustive endurance exercise. Hypothetically, exercise-induced DNA damage might either be a consequence of inflammatory processes or causally involved in inflammation and immunological alterations after strenuous prolonged exercise (e.g. by inducing lymphocyte apoptosis and lymphocytopenia). Nevertheless, up to now only few studies have addressed this issue and there is hardly any evidence regarding a direct relationship between DNA or chromosomal damage and inflammatory responses in the context of exercise. The most conclusive picture that emerges from available data is that reactive oxygen and nitrogen species (RONS) appear to be the key effectors which link inflammation with DNA damage. Considering the time-courses of inflammatory and oxidative stress responses on the one hand and DNA effects on the other the lack of correlations between these responses might also be explained by too short observation periods. This review summarizes and discusses the recent findings on this topic. Furthermore, data from our own study are presented that aimed to verify potential associations between several endpoints of genome stability and inflammatory, immune-endocrine and muscle damage parameters in competitors of an Ironman triathlon until 19 days into recovery. The current results indicate that DNA effects in lymphocytes are not responsible for exercise-induced inflammatory responses. Furthermore, this investigation shows that inflammatory processes, vice versa, do not promote DNA damage, neither directly nor via an increased formation of RONS derived from inflammatory cells. Oxidative DNA damage might have been counteracted by training- and exercise-induced antioxidant responses. However, further studies are needed that combine advanced -omics based techniques (transcriptomics, proteomics) with state-of-the-art biochemical biomarkers to gain more insights into the underlying mechanisms.

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Antioxidant requirements have neither been defined for endurance nor been defined for ultra-endurance athletes. To verify whether an acute bout of ultra-endurance exercise modifies the need for nutritive antioxidants, we aimed (1) to investigate the changes of endogenous and exogenous antioxidants in response to an Ironman triathlon; (2) to particularise the relevance of antioxidant responses to the indices of oxidatively damaged blood lipids, blood cell compounds and lymphocyte DNA and (3) to examine whether potential time-points of increased susceptibility to oxidative damage are associated with alterations in the antioxidant status. Blood that was collected from forty-two well-trained male athletes 2 d pre-race, immediately post-race, and 1, 5 and 19 d later was sampled. The key findings of the present study are as follows: (1) Immediately post-race, vitamin C, alpha-tocopherol, and levels of the Trolox equivalent antioxidant capacity, the ferric reducing ability of plasma and the oxygen radical absorbance capacity (ORAC) assays increased significantly. Exercise-induced changes in the plasma antioxidant capacity were associated with changes in uric acid, bilirubin and vitamin C. (2) Significant inverse correlations between ORAC levels and indices of oxidatively damaged DNA immediately and 1 d post-race suggest a protective role of the acute antioxidant responses in DNA stability. (3) Significant decreases in carotenoids and gamma-tocopherol 1 d post-race indicate that the antioxidant intake during the first 24 h of recovery following an acute ultra-endurance exercise requires specific attention. Furthermore, the present study illustrates the importance of a diversified and well-balanced diet to maintain a physiological antioxidant status in ultra-endurance athletes in reference to recommendations.

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It is commonly accepted that regular moderate intensity physical activity reduces the risk of developing many diseases. Counter intuitively, however, evidence also exists for oxidative stress resulting from acute and strenuous exercise. Enhanced formation of reactive oxygen and nitrogen species may lead to oxidatively modified lipids, proteins and nucleic acids and possibly disease. Currently, only a few studies have investigated the influence of exercise on DNA stability and damage with conflicting results, small study groups and the use of different sample matrices or methods and result units. This is the first review to address the effect of exercise of various intensities and durations on DNA stability, focusing on human population studies. Furthermore, this article describes the principles and limitations of commonly used methods for the assessment of oxidatively modified DNA and DNA stability. This review is structured according to the type of exercise conducted (field or laboratory based) and the intensity performed (i.e. competitive ultra/endurance exercise or maximal tests until exhaustion). The findings presented here suggest that competitive ultra-endurance exercise (>4h) does not induce persistent DNA damage. However, when considering the effects of endurance exercise (<4h), no clear conclusions could be drawn. Laboratory studies have shown equivocal results (increased or no oxidative stress) after endurance or exhaustive exercise. To clarify which components of exercise participation (i.e. duration, intensity and training status of subjects) have an impact on DNA stability and damage, additional carefully designed studies combining the measurement of DNA damage, gene expression and DNA repair mechanisms before, during and after exercise of differing intensities and durations are required.

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Regular moderate physical activity reduces the risk of several noncommunicable diseases. At the same time, evidence exists for oxidative stress resulting from acute and strenuous exercise by enhanced formation of reactive oxygen and nitrogen species, which may lead to oxidatively modified lipids, proteins, and possibly negative effects on DNA stability. The limited data on ultraendurance events such as an Ironman triathlon show no persistent DNA damage after the events. However, when considering the effects of endurance exercise comparable to a (half) marathon or a short triathlon distance, no clear conclusions could be drawn. In order to clarify which components of exercise participation, such as duration, intensity, frequency, or training status of the subjects, have an impact on DNA stability, more information is clearly needed that combines the measurement of DNA damage, gene expression, and DNA repair mechanisms before, during, and after exercise of differing intensities and durations.

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Purpose We determined the effect of reduced muscle glycogen availability on cellular pathways regulating mitochondrial biogenesis and substrate utilization after a bout of resistance exercise. Methods Eight young, recreationally trained men undertook a glycogen depletion protocol of one-leg cycling to fatigue (LOW), while the contralateral (control) leg rested (CONT). Following an overnight fast, subjects completed 8 sets of 5 unilateral leg press repetitions (REX) at 80 % 1 Repetition Maximum (1RM) on each leg. Subjects consumed 500 mL protein/CHO beverage (20 g whey + 40 g maltodextrin) upon completion of REX and 2 h later. Muscle biopsies were obtained at rest and 1 and 4 h after REX in both legs. Results Resting muscle glycogen was higher in the CONT than LOW leg (~384 ± 114 vs 184 ± 36 mmol kg−1 dry wt; P < 0.05), and 1 h and 4 h post-exercise (P < 0.05). Phosphorylation of p53Ser15 increased 1 h post-exercise in LOW (~115 %, P < 0.05) and was higher than CONT at this time point (~87 %, P < 0.05). p38MAPKThr180/Tyr182 phosphorylation increased 1 h post-exercise in both CONT and LOW (~800–900 %; P < 0.05) but remained above rest at 4 h only in CONT (~585 %, P < 0.05; different between legs P < 0.05). Peroxisome proliferator-activated receptor gamma coactivator-1α (PGC-1α) mRNA was elevated 4 h post-exercise in LOW (~200 %, P < 0.05; different between legs P < 0.05). There were no changes in Fibronectin type III domain-containing protein 5 (FNDC5) mRNA for CONT or LOW legs post-exercise. Conclusion Undertaking resistance exercise with low glycogen availability may enhance mitochondrial-related adaptations through p53 and PGC-1α-mediated signalling.