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1.
Mitochondrial stress and mitokines in aging.
Burtscher, J, Soltany, A, Visavadiya, NP, Burtscher, M, Millet, GP, Khoramipour, K, Khamoui, AV
Aging cell. 2023;(2):e13770
Abstract
Mitokines are signaling molecules that enable communication of local mitochondrial stress to other mitochondria in distant cells and tissues. Among those molecules are FGF21, GDF15 (both expressed in the nucleus) and several mitochondrial-derived peptides, including humanin. Their responsiveness to mitochondrial stress induces mitokine-signaling in response for example to exercise, following mitochondrial challenges in skeletal muscle. Such signaling is emerging as an important mediator of exercise-derived and dietary strategy-related molecular and systemic health benefits, including healthy aging. A compensatory increase in mitokine synthesis and secretion could preserve mitochondrial function and overall cellular vitality. Conversely, resistance against mitokine actions may also develop. Alterations of mitokine-levels, and therefore of mitokine-related inter-tissue cross talk, are associated with general aging processes and could influence the development of age-related chronic metabolic, cardiovascular and neurological diseases; whether these changes contribute to aging or represent "rescue factors" remains to be conclusively shown. The aim of the present review is to summarize the expanding knowledge on mitokines, the potential to modulate them by lifestyle and their involvement in aging and age-related diseases. We highlight the importance of well-balanced mitokine-levels, the preventive and therapeutic properties of maintaining mitokine homeostasis and sensitivity of mitokine signaling but also the risks arising from the dysregulation of mitokines. While reduced mitokine levels may impair inter-organ crosstalk, also excessive mitokine concentrations can have deleterious consequences and are associated with conditions such as cancer and heart failure. Preservation of healthy mitokine signaling levels can be achieved by regular exercise and is associated with an increased lifespan.
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2.
How much resistance exercise is beneficial for healthy aging and longevity?
Burtscher, J, Strasser, B, D'Antona, G, Millet, GP, Burtscher, M
Journal of sport and health science. 2023;(3):284-286
Abstract
• Resistance exercise (RE) is an important physical activity modality conferring major health benefits that are partially complementary to benefits from endurance exercise. • Recent meta-analyses reveal a U-shaped relationship between RE volumes and mortality, with optimal benefits achieved at about 60 min of RE per week. • The mechanisms for potential adverse effects at higher RE volumes are unknown and may be due to hitherto undefined confounders and/or specific individual vulnerabilities. • Wearable technologies and advanced data analysis methods provide exciting tools to explore such risk factors. • Presently, there is no convincing reason for healthy individuals to reduce their RE activities.
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3.
Immune consequences of exercise in hypoxia: A narrative review.
Burtscher, J, Pasha, Q, Chanana, N, Millet, GP, Burtscher, M, Strasser, B
Journal of sport and health science. 2023
Abstract
Immune outcomes are key mediators of many health benefits of exercise and are determined by exercise type, dose (frequency/duration, intensity), and individual characteristics. Similarly, reduced availability of ambient oxygen (hypoxia) modulates immune functions depending on the hypoxic dose and the individual capacity to respond to hypoxia. How combined exercise and hypoxia (e.g., high-altitude training) sculpts immune responses is not well understood, although such combinations are becoming increasingly popular. Therefore, in this paper, we summarize the impact on immune responses of exercise and of hypoxia, both independently and together, with a focus on specialized cells in the innate and adaptive immune system. We review the regulation of the immune system by tissue oxygen levels and the overlapping and distinct immune responses related to exercise and hypoxia, then we discuss how they may be modulated by nutritional strategies. Mitochondrial, antioxidant, and anti-inflammatory mechanisms underlie many of the adaptations that can lead to improved cellular metabolism, resilience, and overall immune functions by regulating the survival, differentiation, activation, and migration of immune cells. This review shows that exercise and hypoxia can impair or complement/synergize with each other while regulating immune system functions. Appropriate acclimatization, training, and nutritional strategies can be used to avoid risks and tap into the synergistic potentials of the poorly studied immune consequences of exercising in a hypoxic state.
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4.
The Impact of Training on the Loss of Cardiorespiratory Fitness in Aging Masters Endurance Athletes.
Burtscher, J, Strasser, B, Burtscher, M, Millet, GP
International journal of environmental research and public health. 2022;(17)
Abstract
Elite masters endurance athletes are considered models of optimal healthy aging due to the maintenance of high cardiorespiratory fitness (CRF) until old age. Whereas a drop in VO2max in masters athletes has been broadly investigated, the modifying impact of training still remains a matter of debate. Longitudinal observations in masters endurance athletes demonstrated VO2max declines between -5% and -46% per decade that were closely related to changes in training volume. Here, using regression analyses, we show that 54% and 39% of the variance in observed VO2max decline in male and female athletes, respectively is explained by changes in training volume. An almost linear VO2max decrease was observed in studies on young and older athletes, as well as non-athletes, starting a few days after training cessation, with a decline of as much as -20% after 12 weeks. Besides a decline in stroke volume and cardiac output, training cessation was accompanied by considerable reductions in citrate synthase and succinate dehydrogenase activity (reduction in mitochondrial content and oxidative capacity). This reduction could largely be rescued within similar time periods of training (re)uptake. It is evident that training reduction or cessation leads to a considerably accelerated VO2max drop, as compared to the gradual aging-related VO2max decline, which can rapidly nullify many of the benefits of preceding long-term training efforts.
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5.
Weight Loss and Fat Metabolism during Multi-Day High-Altitude Sojourns: A Hypothesis Based on Adipocyte Signaling.
Pramsohler, S, Burtscher, M, Rausch, L, Netzer, NC
Life (Basel, Switzerland). 2022;(4)
Abstract
Several publications and random observations have reported weight loss in high-altitude sojourners of both sexes. This could be a result of multiple adaptations, which hypoxia and mountaineering provoke on a cellular and organic level. Several publications have discussed the effect on appetite-regulating hormones to be one of the main contributing factors. We aimed to review the available data and show the current state of knowledge regarding nutritional aspects in high altitude with a special focus on fatty dietary forms. To reach this aim we conducted a literature search via PubMed according to the PRISMA 2020 protocol to identify relevant studies. We found that very few studies cover this field with scientifically satisfying evidence. For final analysis, reviews as well as papers that were not clearly related to the topic were excluded. Six articles were included discussing hormonal influences and the impact of exercise on appetite regulation as well as genetic factors altering metabolic processes at altitude. Leptin expression seems to be the biggest contributor to appetite reduction at altitude with an initial increase followed by a decrease in the course of time at high altitude. Its expression is greatly dependent on the amount of white adipose tissue. Since the expression of leptin is associated with an increased β-oxidation of fatty acids, a high-fat diet could be advantageous at a certain time point in the course of high-altitude sojourns.
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6.
Nutrition for Older Athletes: Focus on Sex-Differences.
Strasser, B, Pesta, D, Rittweger, J, Burtscher, J, Burtscher, M
Nutrients. 2021;(5)
Abstract
Regular physical exercise and a healthy diet are major determinants of a healthy lifespan. Although aging is associated with declining endurance performance and muscle function, these components can favorably be modified by regular physical activity and especially by exercise training at all ages in both sexes. In addition, age-related changes in body composition and metabolism, which affect even highly trained masters athletes, can in part be compensated for by higher exercise metabolic efficiency in active individuals. Accordingly, masters athletes are often considered as a role model for healthy aging and their physical capacities are an impressive example of what is possible in aging individuals. In the present review, we first discuss physiological changes, performance and trainability of older athletes with a focus on sex differences. Second, we describe the most important hormonal alterations occurring during aging pertaining regulation of appetite, glucose homeostasis and energy expenditure and the modulatory role of exercise training. The third part highlights nutritional aspects that may support health and physical performance for older athletes. Key nutrition-related concerns include the need for adequate energy and protein intake for preventing low bone and muscle mass and a higher demand for specific nutrients (e.g., vitamin D and probiotics) that may reduce the infection burden in masters athletes. Fourth, we present important research findings on the association between exercise, nutrition and the microbiota, which represents a rapidly developing field in sports nutrition.
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7.
5-Hydroxymethylfurfural and α-ketoglutaric acid supplementation increases oxygen saturation during prolonged exercise in normobaric hypoxia.
Kössler, F, Mair, L, Burtscher, M, Gatterer, H
International journal for vitamin and nutrition research. Internationale Zeitschrift fur Vitamin- und Ernahrungsforschung. Journal international de vitaminologie et de nutrition. 2021;(1-2):63-68
Abstract
This double-blinded, randomized and placebo-controlled, crossover study investigated whether α-ketoglutaric-acid (α-KG) and 5-hydroxymethylfurfural (5-HMF) supplementation improves exercise performance in hypoxia and affects physiological responses during the exercise task. Eight moderately trained male participants (age: 25.3 ± 2.0 y, VO2max: 48.0 ± 8.3 ml/min/kg) performed an incremental exercise test to exhaustion in normoxia and two 2-hour cycle time trial (TT) tests in hypoxia (3,500 m) each separated by 1-week. Prior to the TT, participants supplemented with either α-KG and 5-HMF or placebo (random order). Supplementation did not improve TT performance at altitude and did not affect heart rate, effort perception and oxidative stress levels (p > 0.05). Oxygen saturation (SpO2) was enhanced during the α-KG and 5-HMF supplementation trial (79.5 ± 3.3 vs. 78.2 ± 3.7%, p = 0.026). Even though TT performance was unaffected, the enhanced SpO2 - possibly originated from changed O2-affinity - deserves further consideration as the exercise performance decline at altitude is strongly linked to the SpO2 decline. The inclusion of moderately fit participants, not specifically cycle trained, might have prevented any visible performance enhancement.
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8.
Acute Effects of a Short Bout of Physical Activity on Cognitive Function in Sport Students.
Niedermeier, M, Weiss, EM, Steidl-Müller, L, Burtscher, M, Kopp, M
International journal of environmental research and public health. 2020;(10)
Abstract
Physical activity is a promising intervention to restore cognitive function after prolonged sedentary periods. However, little is known about the effect of short physical activity bouts on cognition especially among individuals that are used to physical activity. Therefore, the goal of the present study was to assess the impact of a single ten-minute physical activity bout on the cognitive domain of visual attention compared to sedentary behavior in a population of physically active sport students. Using a randomized controlled design, 51 healthy and physically active sport students [mean age: 22.3 (SD: 2.0) years, 33.3% female] were allocated to one of the following interventions in the break of a two-hour study course: physical activity group (running for ten minutes) and sedentary control group. Visual attention was measured post-intervention using a modified trail making test. Pre-, post-, and 30 min after intervention, perceived attention, and affective states were measured. Between-group comparisons were used to analyze whether visual attention and/or changes in perceived attention or affective states differed between groups. The physical activity group showed significantly higher visual attention post-intervention compared with the sedentary control group, p = 0.003, d = 0.89. Perceived attention, p = 0.006, d = 0.87, and arousal, p < 0.001, d = 1.68, showed a significantly larger pre- and post-intervention increase in the physical activity group compared with the sedentary control group, which was not evident 30 min after intervention. A single ten-minute running intervention in study breaks might help to restore the basal visual attentional domain of cognition after prolonged sedentary periods more effectively compared with common sedentary behavior in breaks between study lessons.
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9.
Are Pre-Ascent Low-Altitude Saliva Cortisol Levels Related to the Subsequent Acute Mountain Sickness Score? Observations from a Field Study.
Gatterer, H, Bernatzky, G, Burtscher, J, Rainer, M, Kayser, B, Burtscher, M
High altitude medicine & biology. 2019;(4):337-343
Abstract
Background: The associations among cortisol levels, body water status, and acute mountain sickness (AMS) remain unclear. We investigated associations between AMS prevalence and severity with resting saliva cortisol levels at low altitude (LA) and high altitude (HA) and with fluid balance during a HA stay. Methods: Twenty-two physically fit and healthy participants (12 women, 10 men) were transported to HA (Testa Grigia, 3480 m). In the late afternoon at LA, on the next day 3-4 hours after arrival at HA and in the morning after an overnight stay, heart rate, oxygen saturation, and systolic and diastolic blood pressures were measured in a sitting position after 10 minutes of rest; cortisol levels were quantified in saliva samples taken pre-ascent and 3-4 hours after arrival at HA. AMS was scored with the 1993 Lake Louise Score (LLS, cut-off ≥3). Urine volume and fluid and food intake were recorded during the altitude stay. Results: Pre-ascent cortisol levels were associated with fluid retention during the altitude stay (r2 = 0.33, p < 0.05) and both were positively related to the LLS (r2 = 0.49 and r2 = 0.26, p < 0.05, respectively). Conclusions: In conclusion, resting LA cortisol levels and fluid retention upon rapid exposure to altitude seem to be associated with AMS. This suggests a potential link among cortisol homeostasis, fluid balance, and AMS risk.
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10.
Role of Dietary Protein and Muscular Fitness on Longevity and Aging.
Strasser, B, Volaklis, K, Fuchs, D, Burtscher, M
Aging and disease. 2018;(1):119-132
Abstract
Muscle atrophy is an unfortunate effect of aging and many diseases and can compromise physical function and impair vital metabolic processes. Low levels of muscular fitness together with insufficient dietary intake are major risk factors for illness and mortality from all causes. Ultimately, muscle wasting contributes significantly to weakness, disability, increased hospitalization, immobility, and loss of independence. However, the extent of muscle wasting differs greatly between individuals due to differences in the aging process per se as well as physical activity levels. Interventions for sarcopenia include exercise and nutrition because both have a positive impact on protein anabolism but also enhance other aspects that contribute to well-being in sarcopenic older adults, such as physical function, quality of life, and anti-inflammatory state. The process of aging is accompanied by chronic immune activation, and sarcopenia may represent a consequence of a counter-regulatory strategy of the immune system. Thereby, the kynurenine pathway is induced, and elevation in the ratio of kynurenine to tryptophan concentrations, which estimates the tryptophan breakdown rate, is often linked with inflammatory conditions and neuropsychiatric symptoms. A combined exercise program consisting of both resistance-type and endurance-type exercise may best help to ameliorate the loss of skeletal muscle mass and function, to prevent muscle aging comorbidities, and to improve physical performance and quality of life. In addition, the use of dietary protein supplementation can further augment protein anabolism but can also contribute to a more active lifestyle, thereby supporting well-being and active aging in the older population.