Weeks Of Exercise Training Research Articles

The effect of intravenous iron supplementation on exercise capacity in iron-deficient but not anaemic patients with chronic kidney disease: study design and baseline data for a multicentre prospective double-blind randomised controlled trial

BackgroundMany people living with chronic kidney disease (CKD) are iron deficient, even though they may not be anaemic. The Iron and Muscle study aims to evaluate whether iron supplementation reduces symptoms of fatigue, improves muscle metabolism, and leads to enhanced exercise capacity and physical function. We report here the trial design and baseline characteristics.MethodsThis is a prospective, double-blind multicentre randomised controlled trial (RCT) including 75 non-dialysis stage 3–4 CKD patients with iron deficiency but without anaemia. Patients were randomly (1:1) assigned to either: i) intravenous iron therapy, or ii) placebo, with concurrent recruitment of eight CKD non-iron deficient participants and six healthy volunteers. The primary outcome of the study is the six-minute walk test (6MWT) distance between baseline and four-weeks. An additional exercise training programme for patients in both groups was initiated and completed between 4 and 12 weeks, to determine the effect of iron repletion compared to placebo treatment in the context of patients undertaking an exercise programme. Additional secondary outcomes include fatigue, physical function, muscle strength, muscle metabolism, quality of life, resting blood pressure, clinical chemistry, safety and harms associated with the iron therapy intervention and the exercise training intervention, and hospitalisations. All outcomes were conducted at baseline, 4, and 12 weeks, with a nested qualitative study, to investigate the experience of living with iron deficiency and intervention acceptability. The cohort have been recruited and baseline assessments undertaken.ResultsSeventy-five individuals were recruited. 44% of the randomised cohort were male, the mean (SD) age was 58 (14) years, and 56% were White. Body mass index was 31 (7) kg/m2; serum ferritin was 59 (45) μg/L, transferrin saturation was 22 (10) %, and haemoglobin was 125 (12) g/L at randomisation for the whole group. Estimated glomerular filtration rate was 35 (12) mL/min/1.73 m2 and the baseline 6MWT distance was 429 (174) m.ConclusionThe results from this study will address a substantial knowledge gap in the effects of intravenous iron therapy, and offer potential clinical treatment options, to improve exercise capacity, physical function, fatigue, and muscle metabolism, for non-dialysis patients with CKD who are iron-deficient but not anaemic. It will also offer insight into the potential novel effects of an 8-week exercise training programme.Trial registrationEudraCT: 2018–000,144-25 Registered 28/01/2019.

Salivary concentrations of IL-8 and IL-1ra after HIIT and MICT in young, healthy adults: A randomized exercise study

The purpose of this study was to determine whether six weeks of high intensity interval training (HIIT) would lead to greater changes in resting concentrations of salivary IL-8 and IL-1ra than moderate intensity continuous training (MICT) in young, healthy adults, and to determine whether changes in IL-8 and IL-1ra after six weeks of either HIIT or MICT were associated with changes in maximal exercise capacity (VO2max). Participants were randomly assigned to 6 weeks of HIIT (n = 12) or MICT (n = 11), matched for workload. Saliva samples were collected at the beginning (T1) and end (T2) of the intervention, and analyzed for IL-8 and IL-1ra. Participants in both groups had significant improvements in VO2max; there were no group differences in improvements. A greater reduction in IL-8 was observed in the MICT group when compared to the HIIT group (HIIT median: −9.5; MICT median: −82.3 pg/µg of protein; U = 11.5, p < 0.001). When combining the HIIT and MICT group, there were significant reductions in IL-8 from T1 to T2. There was no correlation between changes in IL-8 (r < 0.00) or IL-1ra (r = −0.013) with changes in VO2max. In conclusion, 6 weeks of exercise training leads to a reduction in IL-8; MICT may lead to greater reductions when compared to HIIT. Future research examining longer intervention periods is needed to further elucidate the effects of HIIT and MICT on different pro and anti-inflammatory cytokines.

Effect of angiotensin-converting enzyme inhibition on cardiovascular adaptation to exercise training.

Angiotensin‐converting enzyme (ACE) activity may be one determinant of adaptability to exercise training, but well‐controlled studies in humans without confounding conditions are lacking. Thus, the purpose of the present study was to investigate whether ACE inhibition affects cardiovascular adaptations to exercise training in healthy humans. Healthy participants of both genders (40 ± 7 years) completed a randomized, double‐blind, placebo‐controlled trial. Eight weeks of exercise training combined with placebo (PLA, n = 25) or ACE inhibitor (ACEi, n = 23) treatment was carried out. Before and after the intervention, cardiovascular characteristics were investigated. Mean arterial blood pressure was reduced (p < 0.001) by −5.5 [−8.4; −2.6] mmHg in ACEi, whereas the 0.7 [−2.0; 3.5] mmHg fluctuation in PLA was non‐significant. Maximal oxygen uptake increased (p < 0.001) irrespective of ACE inhibitor treatment by 13 [8; 17] % in ACEi and 13 [9; 17] % in PLA. In addition, skeletal muscle endurance increased (p < 0.001) to a similar extent in both groups, with magnitudes of 82 [55; 113] % in ACEi and 74 [48; 105] % in PLA. In contrast, left atrial volume decreased (p < 0.05) by −9 [−16; −2] % in ACEi, but increased (p < 0.01) by 14 [5; 23] % in PLA. Total hemoglobin mass was reduced (p < 0.01) by −3 [−6; −1] % in ACEi, while a non‐significant numeric increase of 2 [−0.4; 4] % existed in PLA. The lean mass remained constant in ACEi but increased (p < 0.001) by 3 [2; 4] % in PLA. In healthy middle‐aged adults, 8 weeks of high‐intensity exercise training increases maximal oxygen uptake and skeletal muscle endurance irrespective of ACE inhibitor treatment. However, ACE inhibitor treatment counteracts exercise training‐induced increases in lean mass and left atrial volume. ACE inhibitor treatment compromises total hemoglobin mass.

Cardiac remodeling in amateur triathletes after 24 weeks of exercise training for a half-Ironman event: a brief report.

Triathletes' physiological adaptations to exercise training can have a different impact on cardiac remodeling based on the extreme exercise preparation. Moreover, cardiac remodeling might be different depending on whether triathletes have trained for many years or if they just decided to be more active. Nevertheless, data are limited in amateur endurance athletes and studies about them are key for their safety. Therefore, we investigated the effects of exercise training for a half-ironman on cardiac remodeling. A total of 24 amateur athletes underwent a 24-week exercise program and were followed by three-dimensional echocardiography to assess its global impact on cardiac remodeling. Subanalyses were performed based on participants past-training experience (low versus high). We found significant group effects on the right and left ventricle, significant time effect on the right ventricle. No significant interaction effects were observed. We observed significant correlations between the right ventricle, clinical and performance characteristics where the peak power output explained 38% of the variance, while the body surface area, weight and power at the second ventilatory threshold explained 34%, 31% and 30%, respectively. Changes in cardiac remodeling in response to an exercise program for a half-ironman are not homogeneous across the ventricles and are influenced by participants' past-training experience. This study strengthens our knowledge of extreme exercise training for a half-ironman to further develop better training programs and medical follow-up in amateur triathletes.

Effects of a 12-week barefoot exercise training on foot muscle functions and arch height

article: Effects of a 12-week barefoot exercise training on foot muscle functions and arch height - Gazzetta Medica Italiana - Archivio per le Scienze Mediche 2022 April;181(4):191-8 - Minerva Medica - Journals

Effect of Different Exercise Training Modalities on Fasting Levels of Oxylipins and Endocannabinoids in Middle-Aged Sedentary Adults: A Randomized Controlled Trial

This study aimed to investigate the effects of different exercise training programs on fasting plasma levels of oxylipins, endocannabinoids (eCBs), and eCBs-like molecules in middle-aged sedentary adults. A 12-week randomized controlled trial was conducted using a parallel group design. Sixty-five middle-aged adults (40-65years old) were randomly assigned to: (a)no exercise (control group), (b)concurrent training based on international physical activity recommendations (PAR group), (c)high-intensity interval training (HIIT group), and (d)HIIT together with whole-body electromyostimulation (HIIT + EMS group). Plasma levels of oxylipins, eCBs, and eCBs-like molecules were determined in plasma samples before and after the intervention using targeted lipidomics. Body composition was assessed through dual-energy X-ray absorptiometry, and dietary intake through a food frequency questionnaire and three nonconsecutive 24-hr recalls. The physical activity recommendations, HIIT, and HIIT-EMS groups showed decreased plasma levels of omega-6 and omega-3-derived oxylipins, and eCBs and eCBs-like molecules after 12weeks (all Δ ≤ -0.12; all p < .05). Importantly, after Bonferroni post hoc corrections, the differences in plasma levels of omega-6 and omega-3 oxylipins were not statistically significant compared with the control group (all p > .05). However, after post hoc corrections, plasma levels of anandamide and oleoylethanolamide were increased in the physical activity recommendations group compared with the control group (anandamide: Δ = 0.05 vs. -0.09; oleoylethanolamide: Δ = -0.12 vs. 0.013, all p ≤ .049). In conclusion, this study reports that a 12-week exercise training intervention, independent of the modality applied, does not modify fasting plasma levels of omega-6 and omega-3 oxylipins, eCBs, and eCBs-like molecules in middle-aged sedentary adults.

ACUTE AEROBIC EXERCISE-INDUCED DECREASE IN BLOOD PRESSURE IS ASSOCIATED WITH CHRONIC BLOOD PRESSURE CHANGES IN PATIENTS WITH RESISTANT HYPERTENSION

Objective: The acute blood pressure (BP) decrease after an exercise training session seems to correlate with the chronic BP reductions following exercise training programs in participants with pre-hypertension; yet, among patients with resistant hypertension (RH) it is unknown. This study aims to investigate the association between the magnitude of BP decrease after acute exercise and the change in 24-hr ambulatory blood pressure (ABP) after an aerobic exercise intervention in patients with RH. Design and method: EnRicH trial was a randomized clinical trial assessing the effects of a 12-week moderate-intensity aerobic exercise program in participants with RH. In the present study, twenty-six patients (mean age 59.3 ± 8.2 years, 58.3% male) with RH that participated in the intervention arm of the EnRicH trial were included. Office and ABP measurements were obtained before and after the 12-week aerobic exercise training program. To assess the acute effect, resting BP measures were assessed before and 10 minutes after each exercise session of the third week of the exercise program. Exercise sessions were supervised, occurred three times per week, and included 40 min of aerobic exercise at 50% to 70% of VO2max and a 10-minute cooldown. Results: Resting systolic (-9.4 ± 7.0, p &lt; 0.001) and diastolic BP (-1.9 ± 3.4, p = 0.10) were significantly reduced after acute exercise. 24hr systolic (-6.2 ± 12.1, p = 0.015) and diastolic BP (-4.42 ± 6.1, p = 0.001) an office systolic (-10.9 ± 15.2, p = 0.001) and diastolic BP (-5.9 ± 11.1, p = 0.013) were significantly decreased after the exercise program. The acute changes were correlated with the chronic decrease in 24hr ambulatory systolic (r = 0.556, p = 0.003) and diastolic (r = 0.484, p = 0.012) BP, and office systolic (r = 0.478, p = 0.014) and diastolic BP (r = 0.452, p = 0.020). Multiple regression analysis revealed that the acute effect of exercise was an independent predictor of the chronic effect on systolic BP (ß = 0.556, adjusted r2 = 0.280, p = 0.003) BP. Conclusions: The magnitude of the acute effect of exercise in BP correlates with the chronic decrease in both office and 24hr BP effects. These results suggest that it is possible to predict those patients that are less likely to improve BP with an exercise training program without the burden of a period of several months of intervention.

RESISTANT HYPERTENSION PATIENTS’ PERSPECTIVES ABOUT AN AEROBIC EXERCISE PROGRAM: INSIGHTS FROM THE ENRICH TRIAL

Objective: Aerobic exercise training programs decrease blood pressure in patients with resistant hypertension. However, patients’ experiences regarding exercise training participation are often undervalued. The aim of this study is to explore the lived experiences of patients with resistant hypertension who participated in a 12-week moderate intensity aerobic exercise training program. Design and method: An exploratory qualitative study was conducted with twenty patients (11 males and 9 females) with resistant hypertension, after the exercise program. Participants’ mean age was 58.9 ± 8.9 years and were taking an average of 4.7 ± 0.9 antihypertensive medications. Focus group interviews were performed to explore participants’ perspectives. The interviews were video-recorded, transcribed verbatim, and submitted to thematic analysis. Results: Five main themes have emerged from interviews’ analyses: 1) impacts of participating in the exercise program; 2) facilitators of adherence to exercise; 3) perceived barriers; 4) perception of the program structure; and 5) global satisfaction with the exercise training program. Overall positive benefits were reported regarding emotional and physical well-being, associated with a decrease in daily life stress and irritability alongside a decrease in blood pressure. Adherence to the physical activity program was facilitated by the commitment to attend the training sessions, different schedule options and the professional and individualized supervision. Participants referred to lack of motivation, absence of company, physical health limitations and difficulty in conciliating schedules as barriers to the maintenance of exercise training. Conclusions: The perceived benefits by the participants are important indicators of adherence and maintenance of exercise training, despite the perceived barriers. This study has an innovative approach by focusing on the participants’ perception analysis, going beyond quantitative clinical data, and providing important insights to increase future participants’ adherence to exercise training programs.

Subjective Well-Being and Bilateral Anterior Insula Functional Connectivity After Exercise Intervention in Older Adults With Mild Cognitive Impairment.

While it is well known that exercise training is associated with improvement in subjective well-being among older adults, it is unclear if individuals with cognitive impairment experience the same effects elicited by exercise on subjective well-being. We further explored whether the bilateral anterior insula network may be an underlying neural mechanism for the exercise training-related improvements in subjective well-being. We investigated the effects of exercise training on subjective well-being in older adults (78.4 ± 7.1 years) with mild cognitive impairment (MCI; n = 14) and a cognitively normal (CN; n = 14) control group. We specifically assessed the relationship between changes in subjective well-being and changes in functional connectivity (FC) with the bilateral anterior insula from before to after exercise training. Cardiorespiratory fitness, subjective well-being, and resting-state fMRI were measured before and after a 12-week moderate-intensity walking intervention. A seed-based correlation analysis was conducted using the bilateral anterior insula as a priori seed regions of interest. The associations between bilateral anterior insula FC with other brain regions and subjective well-being were computed before and after exercise training, respectively, and the statistical difference between the correlations (before vs after exercise training) was evaluated. There was a significant Group (MCI vs CN) × Time (before vs after exercise training) interaction for subjective well-being, such that while those with MCI demonstrated significantly increased subjective well-being after exercise training, no changes in subjective well-being were observed in CN. Participants with MCI also showed an exercise training-related increase in the bilateral anterior insula FC. While there was no significant correlation between subjective well-being and bilateral anterior insula FC before exercise training, a positive association between subjective well-being and bilateral anterior insula FC was found in the MCI group after exercise training. Our findings indicate that 12 weeks of exercise training may enhance subjective well-being in older adults diagnosed with MCI and, further, suggest that increased bilateral anterior insula FC with other cortical regions may reflect neural network plasticity associated with exercise training-related improvements in subjective well-being.

MO602: Combined and Progressive Intradialytic Exercise Training Keeps Stable the Systemic Inflammation, Endothelial Function Markers and Redox State: A Secondary Analysis of a Randomized Controlled Trial

Abstract BACKGROUND AND AIMS Chronic inflammatory conditions and disturbances in oxidative stress are hallmarks of renal damage and may be a trigger to non-pharmacological therapeutic options, such as exercise training, in chronic kidney disease[1,2]. This study aimed to evaluate the effects of 12-week combined and progressive intradialytic exercise training on systemic inflammation, endothelial function markers, and redox state in hemodialysis (HD) patients. METHOD This is a secondary analysis of a randomized controlled trial with HD patients[3] randomly allocated into two groups: exercise group (EXG) (n = 19) and usual care/control group (CON) (n = 19). EXG performed a 12-week combined and progressive intradialytic training period 3 times a week. CON maintained their normal HD routine during the same timeframe. Blood samples were obtained before and after the 12-week period to analyze C-reactive protein (CRP), interleukin (IL)-4, IL-6, IL-10, IL-17A, tumoral necrosis factor-alpha (TNF-α), reactive oxygen species (ROS), total antioxidant capacity (TAC), monocyte chemoattractant protein-1 (MCP-1), interferon-gamma (IFN-γ), vascular endothelial growth factor (VEGF), and nitric oxide (NO). The inflammatory balance was evaluated by IL-6/TNF-α, TNF-α/IL-4 and TNF-α/IL-10 ratios. RESULTS A significant effect was only observed in CON but not EXG, with decreased IL-6 (median of 9.93 [IQR: 8.31–14.79] to 8.86 [7.88–9.61] pg/mL; P = 0.044), IL-17A (62.26 [48.87–102.44] to 53.33 [45.29–59.58] pg/mL; P = 0.044), and IFN-γ (28.19 [26.44–31.15] to 27.09 [25.85–27.89] pg/mL; P = 0.006) and an increase in ROS (485.98 [333.17–604.83] to 507.31 [443.48–637.04]; P = 0.049). CONCLUSION The HD patients who undertook the 12-week combined and progressive intradialytic exercise training did not experience an alteration in systemic inflammation, endothelial function markers and redox state, in contrast with the increased oxidative stress state observed in CON. FUNDING SOURCES Hospital de Clínicas de Porto Alegre–Research Incentive Fund (FIPE) (Grant No. 2015–0151) and Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES).

MOTS‐c protein expression increases following aerobic exercise training and remains elevated during detraining

Mitochondrial open reading frame of the 12S rRNA‐c (MOTS‐c) is a mitochondrial‐derived peptide that is released into the circulation following intense physical activity and, purportedly, has systemic impacts on energy metabolism and insulin sensitivity. Exogenous administration of MOTS‐c in rodent models enhances physical activity / endurance and reduces fat mass in aged mice through the regulation of, in part, the glycolysis / pentose phosphate pathway and amino acid metabolism. Considering that mitochondrial volume and mitochondrial DNA copy number increase following chronic aerobic exercise training, we hypothesized that MOTS‐c expression also would be elevated in exercise‐trained skeletal muscle. MOTS‐c protein expression from phenotypically mixed plantaris muscles of adult female Sprague Dawley rats were compared from six conditions: sedentary (SED; n=11), voluntary exercise training for four (EX4; n=9), six (EX6; n=6), or eight weeks (EX8; n=8), and detraining after four (DETR4) or six (DETR6) weeks, which followed four or six weeks of exercise training, respectively. Total running distances were ~551±61, 371±94, 560±71, 321±44, and 519±27 km for EX4, EX6, EX8, DETR4 and DETR6, respectively. DETR4 rat running distance was significantly lower than EX4, EX8, and DETR6 rats (p&lt;0.01). Total muscle protein homogenate was isolated from mid‐belly muscle chunks and separated using 15% SDS‐PAGE gels (10 μg/sample). Following transfer, membranes were incubated with a custom rabbit anti‐rat MOTS‐c polyclonal antibody, developed, scanned, stripped and re‐probed for GAPDH as a loading control. MOTS‐c protein was significantly elevated from SED (set at 100%) to 188±61, 158±37, 212±27, 168±29, 223±36% in EX4, EX6, EX8, DETR4 and DETR6, respectively (p&lt;0.05). Furthermore, preliminary findings indicate that MOTS‐c is present exclusively within the cytoplasm of skeletal muscle and not compartmentalized within the nuclei or mitochondria. Given that long‐term aerobic exercise augments mitochondrial volume within skeletal muscle, our data suggest that the observed increase in MOTS‐c protein in the present study parallels this mitochondrial adaptation to aerobic physical activity. Taken together, these findings indicate that a more aerobically‐trained individual would have an enhanced MOTS‐c presence within skeletal muscle and, therefore, a greater potential to regulate energy and insulin sensitivity when MOTS‐c is released systemically; additionally, the potential benefits of MOTS‐c are sustained during a period of physical inactivity (e.g., detraining) following exercise training.

Preconditioning Exercise Protects Against Tumor‐Mediated Muscle Dysfunction in the Male Mouse

BackgroundCancer is associated with cardiac and skeletal muscle wasting. While exercise has been shown to be myoprotective, less is known about the most effective “dose” of exercise in terms of intensity, timing, and duration. Therefore, the purpose of this study was to determine the effects of preconditioning exercise – exercise completedJ before tumor bearing ‐ as a protective measure for tumor‐mediated muscle wasting.MethodsMale mice were randomly separated into four groups: sedentary non‐tumor bearing (SED+NT), sedentary tumor bearing (SED+T), treadmill exercise non‐tumor bearing (TM+NT), and treadmill exercise tumor bearing (TM+T). Mice underwent an 8‐week progressive treadmill exercise training protocol (TM) or remained sedentary (SED). At the end of the preconditioning treadmill training protocol, mice remained sedentary for 4 weeks. During this 4 week sedentary period, mice were implanted with tumor cells (T group; 1x105 LLC cells in flank) or remained non‐tumor (NT). To determine whether 8 weeks of exercise preconditioning could preserve cardiac and skeletal muscle function, mice underwent echocardiogram and grip strength analyses at baseline, 8‐week, and 12‐week time points.ResultsTumor bearing resulted in significant muscle dysfunction. SED+T showed a significant decrease in fractional shortening (p&lt;0.05) and grip strength (p&lt;0.05) when compared to all other groups. This coincided with SED+T’s significantly smaller heart masses and skeletal masses (p&lt;0.05 vs to all other groups). Interestingly, preconditioning exercise (exercise prior to tumor bearing) appeared to offer myoprotection since TM groups were not significantly different from SED+NT for fractional shortening and grip strength (p&gt;0.05). This data was in step with preserved heart mass and skeletal muscle mass in TM+T (p&gt;0.05 vs SED+NT).ConclusionThese data indicate that exercise initiated prior to tumor bearing can protect the musculature from tumor‐mediated muscle dysfunction. This may be attributed to slowed muscle wasting as evidenced by maintenance of muscle mass in TM+T groups. These data make an important case for the long‐term benefits of an active lifestyle that last even after exercise is stopped (i.e., upon diagnosis and treatment). Such information is critical in elucidating the most effective “dose” of exercise for cancer survivors.

Cardioprotective Effects of Preconditioning Exercise in the Female Tumor‐Bearing Mouse

BackgroundCancer cachexia, a metabolic wasting syndrome, affects up to 80% of cancer patients and leads to the death in up to 20% of cancer patients. While research is growing in the field, there are still no clear diagnostic criteria and cancer cachexia remains an untreated condition. Aerobic exercise has been shown to positively impact cachexia by slowing its development and attenuating muscle loss. The most effective timing, duration, and intensity of exercise as a preventative and protective measure against cancer cachexia remains questionable. Therefore, the purpose of this study was to examine the effects of preconditioning exercise as a protective measure for tumor‐mediated muscle wasting.MethodsFemale LC3 Tg+ and WT mice were randomly separated into four groups, sedentary non‐tumor bearing (SED+NT), sedentary tumor bearing (SED+T), treadmill exercise non‐tumor bearing (TM+NT), and treadmill exercise tumor bearing (TM+T). Mice underwent an 8‐week treadmill exercise training protocol (TM) or remained sedentary (SED). Next, mice were implanted with tumor cells (T group; 1x105 LLC cells in flank) or remained non‐tumor (NT) for 4 weeks. To examine the protective effects of exercise on tumor growth and muscle wasting during tumor‐mediated muscle wasting, grip strength and tumor growth evaluations were taken at baseline, 8‐week, and 12‐week time points. At the end of the 12‐week study, muscle and tumor tissue was collected and weighed.ResultsTumor bearing resulted in a significant decline in cardiac function. SED+T showed a significant decrease in fractional shortening (P &lt; 0.05) when compared to the other groups. This coincided with an increase in beclin‐1 expression in SED+T mice. Interestingly, preconditioning exercise (exercise prior to tumor bearing) appeared to preserve cardiac function (TM+T not significantly different than SED+NT). Exercise‐mediated cardioprotection also coincided with abolished beclin‐1 signaling since this was not significantly elevated in TM+T mice. Additionally, TM resulted in a 20‐fold decrease in estimated tumor volume (P &lt; 0.05) and a 60% decrease in tumor mass (P &lt; 0.05) compared to SED tumors.ConclusionThe data indicate potential cardioprotective effects of preconditioning exercise on preserving cardiac structure and function, as well as regulating autophagic pathways (beclin‐1) during tumor bearing. Preconditioning exercise may be an effective and accessible treatment intervention for early‐stage cancer survivors. This data is crucial in identifying the significance of exercise and the timing of exercise as a protective measure against the detrimental effects of cancer cachexia.

Exercise training does not affect heat tolerance in Chinook salmon (Oncorhynchus tshawytscha)

The progression of climate warming will expose ectotherms to transient heatwave events and temperatures above their tolerance range at increased frequencies. It is therefore pivotal that we understand species' physiological limits and the capacity for various controls to plastically alter these thresholds. Exercise training could have beneficial impacts on organismal heat tolerance through improvements in cardio-respiratory capacity, but this remains unexplored. Using juvenile Chinook salmon (Oncorhynchus tshawytscha), we tested the hypothesis that exercise training improves heat tolerance through enhancements in oxygen-carrying capacity. Fish were trained once daily at 60% of their maximum sustainable swim speed, UCRIT, for 60 min. Tolerance to acute warming was assessed following three weeks of exercise training, measured as the critical thermal maximum (CTMAX). CTMAX measurements were coupled with examinations of the oxygen carrying capacity (haematocrit, haemoglobin concentration, relative ventricle size, and relative splenic mass) as critical components of the oxygen transport cascade in fish. Contrary to our hypothesis, we found that exercise training did not raise the CTMAX of juvenile Chinook salmon with a mean CTMAX increase of just 0.35 °C compared to unexercised control fish. Training also failed to improve the oxygen carrying capacity of fish. Exercise training remains a novel strategy against acute warming that requires substantial fine-tuning before it can be applied to the management of commercial and wild fishes.

Effects of Foot-Core Training on Foot-Ankle Kinematics and Running Kinetics in Runners: Secondary Outcomes From a Randomized Controlled Trial.

This study investigated the effectiveness of an 8-week foot-core exercise training program on foot-ankle kinematics during running and also on running kinetics (impact loads), with particular interest in biomechanical outcomes considered risk factors for running-related injuries in recreational runners. A single-blind, randomized, controlled trial was conducted with 87 recreational runners randomly allocated to either the control (CG) or intervention (IG) group and assessed at baseline and after 8 weeks. The IG underwent foot-core training 3 times/week, while the CG followed a placebo lower-limb stretching protocol. The participants ran on a force-instrumented treadmill at a self-selected speed while foot-segment motion was captured simultaneously with kinetic measurements. After the intervention, there were statistically significant changed in foot biomechanics, such as: IG participants strike the ground with a more inverted calcaneus and a less dorsiflexed midfoot than those in the CG; at midstance, ran with a less plantarflexed and more adducted forefoot and a more abducted hallux; and at push-off, ran with a less dorsiflexed midfoot and a less adducted and more dorsiflexed hallux. The IG runners also had significantly decreased medial longitudinal arch excursion (p = 0.024) and increased rearfoot inversion (p = 0.037). The 8-week foot-core exercise program had no effect on impact (p = 0.129) and breaking forces (p = 0.934) or on vertical loading rate (p = 0.537), but it was positively effective in changing foot-ankle kinematic patterns.”

AMP-activated protein kinase activation in skeletal muscle modulates exercise-induced uncoupled protein 1 expression in brown adipocyte in mouse model.

Aerobic exercise is an effective intervention in preventing obesity and is also an important factor associated with thermogenesis. There is an increasing interest in the factors and mechanisms induced by aerobic exercise that can influence the metabolism and thermogenic activity in an individual. Recent studies suggest that exercise induced circulating factors (known as ‘exerkines’), which are able to modulate activation of brown adipose tissue (BAT) and browning of white adipose tissue. However, the underlying molecular mechanisms associated with the effect of exercise‐induced peripheral factors on BAT activation remain poorly understood. Furthermore, the role of exercise training in BAT activation is still debatable. Hence, the purpose of our study is to assess whether exercise training affects the expression of uncoupled protein 1 (UCP1) in brown adipocytes via release of different blood factors. Four weeks of exercise training significantly decreased the body weight gain and fat mass gain. Furthermore, trained mice exhibit higher levels of energy expenditure and UCP1 expression than untrained mice. Surprisingly, treatment with serum from exercise‐trained mice increased the expression of UCP1 in differentiated brown adipocytes. To gain a better understanding of these mechanisms, we analysed the conditioned media obtained after treating the C2C12 myotubes with an AMP‐activated protein kinase (AMPK) activator (AICAR; 5‐aminoimidazole‐4‐carboxamide ribonucleotide), which leads to an increased expression of UCP1 when added to brown adipocytes. Our observations suggest the possibility of aerobic exercise‐induced BAT activation via activation of AMPK in skeletal muscles.Key points Exercise promotes thermogenesis by activating uncoupling protein 1 (UCP1), which leads to a decrease in the body weight gain and body fat content. However, little is known about the role of exerkines in modulating UCP1 expression and subsequent brown adipose tissue (BAT) activation.Four weeks of voluntary wheel‐running exercise reduces body weight and fat content.Exercise induces the increase in AMP‐activated protein kinase (AMPK) and slow‐type muscle fibre marker genes in skeletal muscles and promotes UCP1 expression in white and brown adipose tissues.Incubation of brown adipocytes with serum isolated from exercise‐trained mice significantly increased their UCP1 gene and protein levels; moreover, conditioned media of AMPK‐activator‐treated C2C12 myotubes induces increased UCP1 expression in brown adipocytes.These results show that aerobic exercise‐induced skeletal muscle AMPK has a significant effect on UCP1 expression in BAT.

Effects of brief periods of combined plyometric exercise and high intensity running training on the fitness performance of male U17 handball players

This study examined the effects of 8-week combined plyometric exercise and high intensity running training (combined training) on the performance fitness in male U17 handball players. Participants were randomly divided between experimental (E; n = 15; age: 16.5 ± 0.4 years) and control (C; n = 13; age: 16.7 ± 0.3 years) groups. The E group performed combined training (4 workshops) twice a week over 8 weeks. Each session lasted approximately 35 min. The C maintained regular in-season training. Before and after the combined training, both groups underwent repeated sprint ability (RSA), sprint performance (5m, 10m, 20m and 30m), change of direction test (Modified change-of-direction T-test (T-half)), vertical jump (squat jump (SJ), counter-movement jump (CMJ), counter-movement jump with aimed arms (CMJA)), horizontal jump (five-jump test (5JT)), strength (1-RM half squat), and 20-meter shuttle run. Group x time interaction showed significant increases on sprint performance ( p &lt; 0.01, 8.6%; p &lt; 0.001, 7.3%; p &lt; 0.05, 6.9%; and p &lt; 0.01, 8.9% over distances of 5m, 10m, 20m and 30m respectively) in E relative to C. The T-half also showed significant gains for E ( p &lt; 0.05, 6.8%), as did vertical jumping ( p &lt; 0.01, 32.7%; p &lt; 0.001, 32.6% and p &lt; 0.001, 23% for SJ, CMJ and CMJA respectively) and horizontal jumping ( p &lt; 0.05, 13.3%) compared to C. Moreover, there were significant improvements of RSA and 20 m shuttle run in E compared to C. However, there were no significant differences in 1-RM half squat between groups. We conclude that the allocation of short periods of a combined training is effective in enhancing performance fitness and thus can be commended to male U17 Handball participants as a potentially useful component of their training.

Increased toe flexor strength does not relate to altered postural sway during static upright standing after 12 weeks of multicomponent exercise training

ABSTRACT This study investigated whether an increase in toe flexor strength influenced postural control during static upright standing after 12 weeks of multicomponent exercise training in healthy young men. Twelve men (18–23 yrs) performed multicomponent exercise 3 days per week for 12 weeks. Twelve additional age-matched men were recruited for the untrained control group. The multicomponent exercise training consisted of strengthening and balance exercises for the foot and leg muscles. Toe flexor strength, foot arch height and postural control were assessed before, during, and after exercise training. Postural control was evaluated using the path of the centre of pressure, which was obtained with a force plate under three standing conditions: double-leg standing with eyes open, double-leg standing with eyes closed, and single-leg standing with eyes open. The dominant leg was used for single-leg standing. After exercise training, toe flexor strength increased by approximately 32% (p < 0.01), whereas the foot arch height did not change. The centre of pressure variables during double-leg standing did not change after exercise training; however, these variables decreased during single-leg standing. None of the variables in the control group changed after exercise training. The relative increase in toe flexor strength was not correlated with the relative improvement in the centre of pressure variables during single-leg standing after 12 weeks of exercise training (total length, r = 0.1734; mean velocity, r = 0.1734; sway area, r = −0.1372). These findings suggest that increased toe flexor strength has no significant effect on static postural control ability after exercise training in young men. Highlights Twelve weeks of multicomponent exercise training aimed at strengthening foot and leg muscles increased toe flexor strength. Multicomponent exercise training did not alter postural stability during double-leg standing, but improved postural stability during single-leg standing. Increased toe flexor strength did not relate to altered postural stability during static upright standings after 12 weeks of exercise training.

Moderate-intensity exercise training reduces vasorelaxation of mesenteric arteries: role of BKCa channels and nitric oxide.

Exercise training (ET) is well established to induce vascular adaptations on the metabolically active muscles. These adaptations include increased function of vascular potassium channels and enhanced endothelium-dependent relaxations. However, the available data on the effect of ET on vasculatures that normally constrict during exercise, such as mesenteric arteries (MA), are scarce and not conclusive. Therefore, this study hypothesized that 10 weeks of moderate-intensity ET would result in adaptations towards more vasoconstriction or/and less vasodilatation of MA. Young Fischer 344 rats were randomly assigned to a sedentary group (SED; n=24) or exercise training group (EXE; n=28). The EXE rats underwent a progressive treadmill ET program for 10 weeks. Isometric tensions of small (SED; 252.9+/-29.5 microm, EXE; 248.6+/-34.4 microm) and large (SED; 397.7+/-85.3 microm, EXE; 414.0+/-86.95 microm) MA were recorded in response to cumulative phenylephrine concentrations (PE; 0-30 microM) in the presence and absence of the BKCa channel blocker, Iberiotoxin (100 nM). In another set of experiments, tensions in response to cumulative concentration-response curves of acetylcholine (ACh) or sodium nitroprusside (SNP) were obtained, and pEC50s were compared. Immunoblotting was performed to measure protein expression levels of the BKCa channel subunits and eNOS. ET did not alter the basal tension of small and large MA but significantly increased their responses to PE, and reduced the effect of BKCa channels in opposing the contractile responses to PE without changes in the protein expression level of BKCa subunits. ET also elicited a size-dependent functional adaptations that involved reduced endothelium-independent and endothelium-dependent relaxations. In large MA the sensitivity to SNP was decreased more than in small MA suggesting impaired nitric oxide (NO)-dependent mechanisms within the vascular smooth muscle cells of ET group. Whereas the shift in pEC50 of ACh-induced relaxation of small MA would suggest more effect on the production of NO within the endothelium, which is not changed in large MA of ET group. However, the eNOS protein expression level was not significantly changed between the ET and SED groups. In conclusion, our results indicate an increase in contraction and reduced relaxation of MA after 10 weeks of ET, an adaptation that may help shunt blood flow to metabolically active tissues during acute exercise.

Can Exercise Training Alter Human Skeletal Muscle DNA Methylation?

Skeletal muscle is highly plastic and dynamically regulated by the body’s physical demands. This study aimed to determine the plasticity of skeletal muscle DNA methylation in response to 8 weeks of supervised exercise training in volunteers with a range of insulin sensitivities. We studied 13 sedentary participants and performed euglycemic hyperinsulinemic clamps with basal vastus lateralis muscle biopsies and peak aerobic activity (VO2 peak) tests before and after training. We extracted DNA from the muscle biopsies and performed global methylation using Illumina’s Methylation EPIC 850K BeadChip. Training significantly increased peak aerobic capacity and insulin-stimulated glucose disposal. Fasting serum insulin and insulin levels during the steady state of the clamp were significantly lower post-training. Insulin clearance rates during the clamp increased following the training. We identified 13 increased and 90 decreased differentially methylated cytosines (DMCs) in response to 8 weeks of training. Of the 13 increased DMCs, 2 were within the following genes, FSTL3, and RP11-624M8.1. Of the 90 decreased DMCs, 9 were within the genes CNGA1, FCGR2A, KIF21A, MEIS1, NT5DC1, OR4D1, PRPF4B, SLC26A7, and ZNF280C. Moreover, pathway analysis showed an enrichment in metabolic and actin-cytoskeleton pathways for the decreased DMCs, and for the increased DMCs, an enrichment in signal-dependent regulation of myogenesis, NOTCH2 activation and transmission, and SMAD2/3: SMAD4 transcriptional activity pathways. Our findings showed that 8 weeks of exercise training alters skeletal muscle DNA methylation of specific genes and pathways in people with varying degrees of insulin sensitivity.