Tinna Traustadóttir

Effects of Testosterone Supplementation for 3-Years on Muscle Performance and Physical Function in Older Men.

Context: Findings of studies of testosterone’s effects on muscle strength and physical function in older men have been inconsistent; its effects on muscle power and fatigability have not been studied. Objective: To determine the effects of testosterone administration for 3 years in older men on muscle strength, power, fatigability, and physical function. Design, Setting, and Participants: This was a double-blind, placebo-controlled, randomized trial of healthy men ≥60 years old with total testosterone levels of 100 to 400 ng/dL or free testosterone levels <50 pg/mL. Interventions: Random assignment to 7.5 g of 1% testosterone or placebo gel daily for 3 years. Outcome Measures: Loaded and unloaded stair-climbing power, muscle strength, power, and fatigability in leg press and chest press exercises, and lean mass at baseline, 6, 18, and 36 months. Results: The groups were similar at baseline. Testosterone administration for 3 years was associated with significantly greater performance in unloaded and loaded stair-climbing power than placebo (mean estimated between-group difference, 10.7 W [95% confidence interval (CI), −4.0 to 25.5], P = 0.026; and 22.4 W [95% CI, 4.6 to 40.3], P = 0.027), respectively. Changes in chest-press strength (estimated mean difference, 16.3 N; 95% CI, 5.5 to 27.1; P < 0.001) and power (mean difference 22.5 W; 95% CI, 7.5 to 37.5; P < 0.001), and leg-press power were significantly greater in men randomized to testosterone than in those randomized to placebo. Lean body mass significantly increased more in the testosterone group. Conclusion: Compared with placebo, testosterone replacement in older men for 3 years was associated with modest but significantly greater improvements in stair-climbing power, muscle mass, and power. Clinical meaningfulness of these treatment effects and their impact on disability in older adults with functional limitations remains to be studied.

Nrf2 mediates redox adaptations to exercise

The primary aim of this review is to summarize the current literature on the effects of acute exercise and regular exercise on nuclear factor erythroid 2-related factor 2 (Nrf2) activity and downstream targets of Nrf2 signaling. Nrf2 (encoded in humans by the NFE2L2 gene) is the master regulator of antioxidant defenses, a transcription factor that regulates expression of more than 200 cytoprotective genes. Increasing evidence indicates that Nrf2 signaling plays a key role in how oxidative stress mediates the beneficial effects of exercise. Episodic increases in oxidative stress induced through bouts of acute exercise stimulate Nrf2 activation and when applied repeatedly, as with regular exercise, leads to upregulation of endogenous antioxidant defenses and overall greater ability to counteract the damaging effects of oxidative stress. The evidence of Nrf2 activation in response to exercise across variety of tissues may be an important mechanism of how exercise exerts its well-known systemic effects that are not limited to skeletal muscle and myocardium. Additionally there are emerging data that results from animal studies translate to humans.

Exercise-induced Nrf2-signaling is impaired in aging

PURPOSE The transcription factor nuclear erythroid-2 like factor-2 (Nrf2) is the master regulator of antioxidant defense. Data from animal studies suggest exercise elicits significant increases in Nrf2 signaling, and that signaling is impaired with aging resulting in decreased induction of phase II detoxifying enzymes and greater susceptibility to oxidative damage. We have previously shown that older adults have lower resistance to an oxidative challenge as compared to young, and that this response is modified with physical fitness and phytonutrient intervention. We hypothesized that a single bout of submaximal exercise would elicit increased nuclear accumulation of Nrf2, and that this response to exercise would be attenuated with aging. METHODS Nrf2 signaling in response to 30-min cycling at 70% VO2max was compared in young (23±1y, n=10) and older (63±1, n=10) men. Blood was collected at six time points; pre-exercise, and 10min, 30min, 1h, 4h, and 24h post-exercise. Nrf2 signaling was determined in peripheral blood mononuclear cells by measuring protein expression by western blot of Nrf2 in whole cell and nuclear fractions, and whole cell SOD1, and HMOX, as well as gene expression (RT-PCR) of downstream Nrf2-ARE antioxidants SOD1, HMOX, and NQO1. RESULTS Baseline differences in protein expression did not differ between groups. The exercise trial elicited significant increase in whole cell Nrf2 (P=0.003) for both young and older groups. Nuclear Nrf2 levels were increased significantly in the young but not older group (P=0.031). Exercise elicited significant increases in gene expression of HMOX1 and NQO1 in the young (P=0.006, and P=0.055, respectively) whereas gene expression in the older adults was repressed. There were no significant differences in SOD1 or HMOX1 protein expression. CONCLUSION These findings indicate a single session of submaximal aerobic exercise is sufficient to activate Nrf2 at the whole cell level in both young and older adults, but that nuclear import is impaired with aging. Additionally we have shown repressed gene expression of downstream antioxidant targets of Nrf2 in older adults. Together these translational data demonstrate for the first time the attenuation of Nrf2 activity in response to exercise in older adults.

Ischemia/reperfusion unveils impaired capacity of older adults to restrain oxidative insult

Age independently predicts poor outcome in a variety of medical settings, including sepsis, trauma, severe burns, and surgery. Because these conditions are associated with oxidative stress, we hypothesized that the capacity to constrain oxidative insult diminishes with age, leading to more extensive oxidative damage during trauma. To test this hypothesis, we used suprasystolic inflation of an arm blood pressure cuff to safely induce localized forearm ischemia/reperfusion (I/R) and quantified plasma F(2)-isoprostane (IsoP) levels in serial blood samples. Before I/R, IsoP levels were similar in young (20-33 years) and older adults (62-81 years). After I/R challenge, the magnitude and duration of increased IsoP levels was significantly greater in older adults. Because aging is associated with declining levels of sex hormones that contribute to the regulation of antioxidant enzyme expression, we then examined the response to I/R in older women receiving hormone replacement therapy and found that these women did not manifest the amplified IsoP response found in untreated older women. These findings demonstrate that aging impairs the ability to restrain oxidative damage after an acute insult, which may contribute to the increased vulnerability of older adults to traumatic conditions and establishes a useful method to identify effective interventions to ameliorate this deficiency.

Brief quiet ego contemplation reduces oxidative stress and mind-wandering

Excessive self-concern increases perceptions of threat and defensiveness. In contrast, fostering a more inclusive and expanded sense of self can reduce stress and improve well-being. We developed and tested a novel brief intervention designed to strengthen a student’s compassionate self-identity, an identity that values balance and growth by reminding them of four quiet ego characteristics: detached awareness, inclusive identity, perspective taking, and growth. Students (N = 32) in their first semester of college who reported greater self-protective (e.g., defensive) goals in the first 2 weeks of the semester were invited to participate in the study. Volunteers were randomly assigned to one of three conditions: quiet ego contemplation (QEC), QEC with virtual reality (VR) headset (QEC-VR), and control. Participants came to the lab three times to engage in a 15-min exercise in a 30-days period. The 15-min QEC briefly described each quiet ego characteristic followed by a few minutes time to reflect on what that characteristic meant to them. Those in the QEC condition reported improved quiet ego characteristics and pluralistic thinking, decreases in a urinary marker of oxidative stress, and reduced mind-wandering on a cognitive task. Contrary to expectation, participants who wore the VR headsets while listening to the QEC demonstrated the least improvement. Results suggest that a brief intervention that reduces self-focus and strengthens a more compassionate self-view may offer an additional resource that individuals can use in their everyday lives.

Feasibility of Measuring Ventilatory Threshold in Adults With Stroke-Induced Hemiparesis: Implications for Exercise Prescription

OBJECTIVES To assess the feasibility of measuring ventilatory threshold (VT) in adults with walking impairments due to stroke. Secondary objectives are to assess reliability of VT over trials; assess whether participants could sustain treadmill walking at VT; and compare mean heart rate during sustained treadmill walking to estimated heart rate reserve (HRR). DESIGN Cross-sectional, single-group design. SETTING University research laboratory. PARTICIPANTS Volunteer sample of adults (N=8) with impaired walking resulting from chronic stroke. INTERVENTIONS Three submaximal treadmill walking tests on 3 separate days; a 30-minute treadmill walking session on a fourth day. MAIN OUTCOME MEASURES Gas exchange variables were measured, and 2 independent observers identified VT. Mean heart rate response to treadmill walking at VT was measured and compared with estimated 40% of HRR. RESULTS VT was measured successfully in 88% of all trials. There was no difference in VT among trials (P=.17). After multiple imputations to account for 3 missing data points, the intraclass correlation coefficient was .87 (95% confidence interval, .80-.95). All participants were able to walk for 20 minutes at VT. Mean ± SD heart rate during the session was 66.0%±8.0% of estimated maximal heart rate. There was no significant difference between mean heart rate and estimated HRR values (P=.70). CONCLUSIONS In adults with impaired walking resulting from stroke, VT can be safely measured during submaximal treadmill walking. Participants were able to sustain walking at VT, and this value may provide an appropriate stimulus for aerobic exercise prescription in this population.

A Quasi Experiment to Determine the Effectiveness of a “Partially Flipped” versus “Fully Flipped” Undergraduate Class in Genetics and Evolution

Two sections of a course on genetics and evolution were taught using active learning. Materials and assessments were identical; the main difference was in the amount of time spent on active learning in the classroom in each section. There was no significant difference in objective student learning outcomes or attitudes toward the course.

Preliminary evidence that age and sex affect exercise-induced hTERT expression

Abstract The ability to repair cellular damage is reduced with aging, resulting in cellular senescence. Telomeres shorten as cells divide but the rate of telomere attrition is modulated by telomerase, an enzyme that adds nucleotides to the chromosome. Shelterin is a protein complex that acts as a negative regulator of telomerase. The aim of the present study was to investigate age‐related differences in telomerase and shelterin responses to acute exercise. We hypothesized that acute exercise would stimulate an increased activity of telomerase (measured by telomerase reverse transcriptase, hTERT) without an increase in activity of shelterin (measured by telomeric repeat binding factor 2, TRF2) in both young and older individuals and that hTERT response would be attenuated in older individuals. Young (22 ± 2 y, n = 11) and older (60 ± 2 y, n = 8) men and women performed 30 min of cycling. Blood was collected pre‐exercise and 30, 60, and 90‐min post‐exercise. The trial induced a significant hTERT response in the cohort as a whole (p < 0.05) with greater increases in the young as compared to the older group (time‐by‐group interaction p < 0.05). As expected, TRF2 did not change in response to the trial, however older individuals had a higher TRF2 response at 60 min (p < 0.05). There was an unexpected sex difference, regardless of age, where men had significantly greater hTERT and TRF2 responses to the acute exercise as compared to women (p < 0.05). These data support the hypothesis that aging is associated with attenuated telomerase activation in response to high‐intensity exercise; however, this was only evident in men. HighlightsA single session of high intensity interval cycling increased hTERT gene expression in young and older men but not in women.The hTERT response was attenuated in older men compared to young.TRF2 gene expression was increased in older men at 60 minute post‐exercise.Sex differences in exercise‐induced telomerase activation were a novel finding and need to be investigated in further detail.

A Tale of Two Sections: An Experiment to Compare the Effectiveness of a Hybrid versus a Traditional Lecture Format in Introductory Microbiology.

Learning outcomes of students in two large sections of an introductory microbiology course (one hybrid, one traditional) were compared. The two sections were identical except for the way in which lecture material was presented (online or in class). The hybrid class did slightly less well than the traditional class, possibly due to less interaction with the material.

Long-Term Testosterone Supplementation in Older Men Attenuates Age-Related Decline in Aerobic Capacity

Context Testosterone increases skeletal muscle mass and strength, but long-term effects of testosterone supplementation on aerobic capacity, or peak oxygen uptake (V̇O2peak), in healthy older men with low testosterone have not been evaluated. Objective To determine the effects of testosterone supplementation on V̇O2peak during incremental cycle ergometry. Design A double-blind, randomized, placebo-controlled, parallel-group trial (Testosterones Effects on Atherosclerosis Progression in Aging Men). Setting Exercise physiology laboratory. Participants Healthy men aged ≥ 60 years with total testosterone levels of 100 to 400 ng/dL (3.5 to 13.9 nmol/L) or free testosterone levels < 50 pg/mL (174 pmol/L). Interventions Randomization to 1% transdermal testosterone gel adjusted to achieve serum levels of 500 to 950 ng/dL or placebo applied daily for 3 years. Main Outcome Measures Change in V̇O2peak. Results Mean (±SD) baseline V̇O2peak was 24.2 ± 5.2 and 23.6 ± 5.6 mL/kg/min for testosterone and placebo, respectively. V̇O2peak did not change in men treated with testosterone but fell significantly in men receiving placebo (average 3-year decrease, 0.88 mL/kg/min; 95% CI, -1.39 to 0.38 mL/kg/min; P = 0.035); the difference in change in V̇O2peak between groups was significant (average 3-year difference, 0.91 mL/kg/min; 95% CI, 0.010 to 0.122 mL/kg/min; P = 0.008). The 1-g/dL mean increase in hemoglobin (P < 0.001) was significantly associated with changes in V̇O2peak in testosterone-treated men. Conclusion The mean 3-year change in V̇O2peak was significantly smaller in men treated with testosterone than in men receiving placebo and was associated with increases in hemoglobin. The difference in V̇O2peak change between groups may indicate attenuation of its expected age-related decline; the clinical meaningfulness of the modest treatment effect remains to be determined.