Intensity Endurance Training Research Articles

Effect of Short Term Weight Reduction by High Intensity of Endurance Training on Body Composition, Muscle Mass and Functions in Male College Wrestling Athletes

OBJECTIVES This study is aimed to investigate the effect of short term weight control by High Intensity Endurance Training(HIET) on body composition, muscle mass and functions male college in male wrestling athletes.METHODS Fifteen male college wrestlers with at least 5 years of career were participated and measured body composition, muscle mass and functions after weight reduction through 6 days of HIET intervention.RESULTS First, WRG (weight reduction group, n=7) showed significant changes after HIET -induced weight reduction in work fatigue at 60 degree/sec during flexion in elbow joints, it showed not significant changes after training-induced weight reduction in peak torque, avg. power, work fatigue at 60 degree/sec and 180 degree/sec during extension and flexion in elbow and knee joints. Second, CG (control group, n=8) showed no significant changes after training-induced weight reduction in peak torque, avg. power, work fatigue at 60 degree/sec and 180 degree/sec during extension and flexion in elbow and knee joints.CONCLUSIONS Taken together, relatively short-term, or 6 days weight loss with HIET may not negatively affect muscle mass and function and may be accompanied by fat loss. Additionally, compared to other short-term weight loss methods, this method would be better not only for wrestling athletes but also the weight division athletes. However, it is important to note that weight loss can partially induce muscle fatigue, and athletes should be prepared for a possible decrease in muscular endurance, depending on their individual characteristics.

Endurance training volume cannot entirely substitute for the lack of intensity.

Very low intensity endurance training (LIT) does not seem to improve maximal oxygen uptake. The purpose of the present study was to investigate if very high volume of LIT could compensate the lack of intensity and is LIT affecting differently low and high intensity performances. Recreationally active untrained participants (n = 35; 21 females) cycled either LIT (mean training time 6.7 ± 0.7 h / week at 63% of maximal heart rate, n = 16) or high intensity training (HIT) (1.6 ± 0.2 h /week, n = 19) for 10 weeks. Two categories of variables were measured: Low (first lactate threshold, fat oxidation at low intensity exercise, post-exercise recovery) and high (aerobic capacity, second lactate threshold, sprinting power, maximal stroke volume) intensity performance. Only LIT enhanced pooled low intensity performance (LIT: p = 0.01, ES = 0.49, HIT: p = 0.20, ES = 0.20) and HIT pooled high intensity performance (LIT: p = 0.34, ES = 0.05, HIT: p = 0.007, ES = 0.48). Overall, very low endurance training intensity cannot fully be compensated by high training volume in adaptations to high intensity performance, but it nevertheless improved low intensity performance. Therefore, the intensity threshold for improving low intensity performance is lower than that for improving high intensity performance. Consequently, evaluating the effectiveness of LIT on endurance performance cannot be solely determined by high intensity performance tests.

Right ventricular remodeling induced by prolonged excessive endurance exercise is mediated by upregulating Wnt/β-catenin signaling in rats

BackgroundThe aim of this study was to develop an animal model to investigate whether prolonged intensive endurance exercise induces RV remodeling, taking into account the involvement of Wnt/β-catenin signaling. MethodsFour-week-old male Wistar rats (100 to 125 g) were assigned to four groups (n = 8/group): 1) sixteen weeks of intensive (36 m/min) exercise (INT), 2) twelve weeks of the intensive exercise followed by four weeks of moderate intensity (18 m/min) exercise (INT + MOD), 3) twelve weeks of the intensive exercise followed by four weeks of detraining (INT + DT), and 4) sedentary rats (SED). The exercise protocols were performed five days a week for one h/day. Echocardiography, real-time PCR, western blotting, and histological staining were performed at the end of week sixteen. ResultsINT rats developed concentric hypertrophy without diastolic dysfunction compared to SED (p = 0.006) and INT + DT (p = 0.035). Wnt1, β-catenin and CyclinD1 proteins in the training groups were significantly higher than SED rats (p < 0.001). Interestingly, INT rats had higher protein levels than INT + DT and INT + MOD (p < 0.001), with higher gene expression compared to SED rats (p < 0.05). There was also a significant increase in collagen deposition in INT rats compared to SED (p = 0.046) and INT + DT (p = 0.034). Furthermore, INT + MOD and INT + DT rats did not show any adverse structural, functional, or histological changes. ConclusionsLong-term intensive endurance training seems to be associated with increased collagen deposition and wall thickness in the RV through Wnt/β-catenin signaling (which is concentration dependent), without changes in diastolic function. Clinical perspectiveOver the past decades, there has been an ongoing debate about whether the structural and functional adaptations of the cardiovascular system in trained endurance athletes are benign physiological responses to training or potentially pathological changes related to disease. While the adaptations of the left heart are well-documented, the remodeling of the right heart remains a subject of discussion. To gain insights into the ability of sustained high-intensity exercise to cause adverse right ventricular (RV) remodeling, we conducted an experimental study in which male rats were trained to run vigorously for 1 h daily over a 16-week period and compared them to a parallel group of sedentary control rats. Our findings revealed that intense long-term exercise induced morphological changes along with fibrosis affecting the RV. These fibrotic changes were a result of the 16-week vigorous exercise training regimen. If these results are confirmed in humans, they suggest that prolonged high-intensity endurance exercise training may lead to adverse cardiac remodeling. Our findings have important potential implications for the assessment of cardiac remodeling in individuals engaged in high-level exercise training.

Monitoring fatigue state with heart rate-based and subjective methods during intensified training in recreational runners.

The purpose of this study was firstly to examine the sensitivity of heart rate (HR)-based and subjective monitoring markers to intensified endurance training; and secondly, to investigate the validity of these markers to distinguish individuals in different fatigue states. A total of 24 recreational runners performed a 3-week baseline period, a 2-week overload period, and a 1-week recovery period. Performance was assessed before and after each period with a 3000m running test. Recovery was monitored with daily orthostatic tests, nocturnal HR recordings, questionnaires, and exercise data. The participants were divided into subgroups (overreached/OR, n=8; responders/RESP, n=12) based on the changes in performance and subjective recovery. The responses to the second week of the overload period were compared between the subgroups. RESP improved their baseline 3000m time (p<0.001) after the overload period (-2.5±1.0%), and the change differed (p<0.001) from OR (0.6±1.2%). The changes in nocturnal HR (OR 3.2±3.1%; RESP -2.8±3.7%, p=0.002) and HR variability (OR -0.7±1.8%; RESP 2.1±1.6%, p=0.011) differed between the subgroups. In addition, the decrease in subjective readiness to train (p=0.009) and increase in soreness of the legs (p=0.04) were greater in OR compared to RESP. Nocturnal HR, readiness to train, and exercise-derived HR-running power index had ≥85% positive and negative predictive values in the discrimination between OR and RESP individuals. In conclusion, exercise tolerance can vary substantially in recreational runners. The results supported the usefulness of nocturnal HR and subjective recovery assessments in recognizing fatigue states.

Endurance exercise has a negative impact on the onset of SOD1-G93A ALS in female mice and affects the entire skeletal muscle-motor neuron axis.

Amyotrophic lateral sclerosis (ALS) is a fatal neuromuscular disease characterized by the degeneration of motor neurons that leads to muscle wasting and atrophy. Epidemiological and experimental evidence suggests a causal relationship between ALS and physical activity (PA). However, the impact of PA on motor neuron loss and sarcopenia is still debated, probably because of the heterogeneity and intensities of the proposed exercises. With this study, we aimed to clarify the effect of intense endurance exercise on the onset and progression of ALS in the SOD1-G93A mouse model. We randomly selected four groups of twelve 35-day-old female mice. SOD1-G93A and WT mice underwent intense endurance training on a motorized treadmill for 8weeks, 5days a week. During the training, we measured muscle strength, weight, and motor skills and compared them with the corresponding sedentary groups to define the disease onset. At the end of the eighth week, we analyzed the skeletal muscle-motor neuron axis by histological and molecular techniques. Intense endurance exercise anticipates the onset of the disease by 1week (age of the onset: trained SOD1-G93A = 63.17 ± 2.25days old; sedentary SOD1-G93A = 70.75 ± 2.45days old). In SOD1-G93A mice, intense endurance exercise hastens the muscular switch to a more oxidative phenotype and worsens the denervation process by dismantling neuromuscular junctions in the tibialis anterior, enhancing the Wallerian degeneration in the sciatic nerve, and promoting motor neuron loss in the spinal cord. The training exacerbates neuroinflammation, causing immune cell infiltration in the sciatic nerve and a faster activation of astrocytes and microglia in the spinal cord. Intense endurance exercise, acting on skeletal muscles, worsens the pathological hallmarks of ALS, such as denervation and neuroinflammation, brings the onset forward, and accelerates the progression of the disease. Our findings show the potentiality of skeletal muscle as a target for both prognostic and therapeutic strategies; the preservation of skeletal muscle health by specific intervention could counteract the dying-back process and protect motor neurons from death. The physiological characteristics and accessibility of skeletal muscle further enhance its appeal as a therapeutic target.

Impact of speed endurance training and high intensity interval training on adult football players&amp;#39; agility

Impact of speed endurance training and high intensity interval training on adult football players&amp;#39; agility

Atrial fibrillation in middle-aged athletes: Impact on left atrial, ventricular and exercise performance.

High volume endurance training may increase the risk of paroxysmal atrial fibrillation (AF) in middle-aged athletes. Limited data are available describing the cardiovascular phenotype of middle-aged endurance athletes, or the impact of AF on atrial function and exercise performance performed in sinus rhythm. The purpose of this study was to characterize LA phasic function at rest and during exercise in athletes with paroxysmal AF, and to determine its impact on exercise performance. Fifteen endurance trained males (EA) (56 ± 5 years) without AF and 14 endurance trained males with paroxysmal AF (EA-AF) (55 ± 8 years) underwent echocardiography during cycle-ergometry at light and moderate intensities. Resting LA maximal volumes were similar between EA and EA-AF (30 ± 4 vs. 29 ± 8 ml/m2, p = 0.50), and there were no differences in atrial electromechanical delay (AEMD). During moderate intensity exercise, EA-AF had reduced LA conduit (30 ± 6 vs. 40 ± 5 ml/m2, p = 0.002) LA booster volumes (17 ± 5 vs. 21 ± 4 ml/m2, p = 0.021), and reduced LV stroke volumes (100 ± 12 vs. 117 ± 16 ml, p = 0.007). These results demonstrate that exercise testing in athletes with AF unmasks evidence of adverse functional cardiac remodelling that may contribute to impaired exercise performance. It is unclear whether these functional alterations are the consequence of AF. Reductions in LA conduit volume, LA booster volume, and LV stroke volume during exercise may be helpful in clinical management and distinguishing pathologic from physiologic remodelling.

The waist injuries and treatment methods of rowers

Rowing is one of the worlds competitive sports, and it is an extremely energy intensive aerobic sport. This sport requires very strict physical fitness for athletes. Therefore, rowers need to withstand extreme load training and ultra-high intensity endurance training, whether in daily training or in actual competitions. Rowers must possess good physical fitness and functional abilities, as well as flexibility and agility. However, the prolonged physical wear and tear experienced by rowing athletes during training and competition can easily lead to sports injuries. Due to the influence of many factors, emphasis has been placed on rowing physical fitness training. In the specific operation process, it is necessary to closely combine the characteristics of rowing and the actual physical condition of athletes and develop a scientific and reasonable plan for rowing and injury treatment. Therefore, this article first starts from the investigation of physical injuries and types of injuries among different athletes and finds that the proportion of waist injuries is the highest. At the same time, it elaborates on the basic reasons for waist injuries, and finally provides rehabilitation treatment plans, allowing rowing athletes to make more progress and development.

Gastrointestinal disorders and leaky gut syndrome in endurance athletes

Gastrointestinal disorders are common in endurance-sport athletes, and can negatively affect physical performance and general health. During long lasting exercises such like ultramarathon, triathlon, marathon a characteristic phenomenon is the increase in the concentration many proinflammatory markers and proteins such like IL-1, IL-6, TNF-alfa, LPS, CK and C-reactive protein. Despite observed biochemical changes on of the typical “side effects” of physical activity is increased intestinal permeability, also called to as leaky gut.&#x0D; Recent research has demonstrated that even one hour of of intense endurance training note even with a maximum work capacity can lead to leaky gut symptoms and gastrointestinal disorders.&#x0D; Increased intestinal permeability is accomplished with changes of numerus molecular biomarkers, that indicate presence of this disease state and the degradation of the intestinal mucosa, such like lipopolysaccharides, zonulin, lactulose/rhamnose ratio, occludin and I-FABP, and many other.&#x0D; The understanding of this processes and understanding of the molecular mechanisms involved in the induction of leaky gut syndrome can lead to funding new methods and means of both avoiding and treating this condition.

Functional and Morphological Adaptations in the Heart of Children Aged 12-14 Years following Two Different Endurance Training Protocols.

This study investigated the cardiac functional and the morphological adaptations because of two endurance training protocols. Untrained children (N = 30, age: 12-14 years) were divided into three groups (N = 10/group). The first group did not perform any session (CONTROL), the second performed ventilatory threshold endurance training (VTT) for 12 weeks (2 sessions/week) at an intensity corresponding to the ventilatory threshold (VT) and the third (IT) performed two sessions per week at 120% of maximal oxygen uptake (VO2max). Two other sessions (30 min running at 55-65% of VO2max) per week were performed in VVT and IT. Echocardiograms (Left Ventricular end Diastolic Diameter, LVEDd; Left Ventricular end Diastolic Volume, LVEDV; Stroke Volume, SV; Ejection Fraction, EF; Posterior Wall Thickness of the Left Ventricle, PWTLV) and cardiopulmonary ergospirometry (VO2max, VT, velocity at VO2max (vVO2max), time in vVO2max until exhaustion (Tlim) was conducted before and after protocols. Significant increases were observed in both training groups in LVEDd (VTT = 5%; IT = 3.64%), in LVEDV (VTT = 23.7%; ITT = 13.6%), in SV (VTT = 25%; IT = 16.9%) but not in PWTLV and EF, after protocols. No differences were noted in the CONTROL group. VO2max and VT increased significantly in both training groups by approximately 9% after training. Our results indicate that intensity endurance training does not induce meaningful functional and morphological perturbations in the hearts of children.

Endurance Training and Cardiovascular Health: Mechanism and Clinical Implications

Introduction and objective:&#x0D; Cardiovascular diseases are the leading cause of death worldwide, but regular physical activity can help reduce the risk of heart disease. Intensive endurance training brings many undeniable benefits but recently there have been scientific studies regarding potential complications that this type of physical activity may cause. This publication attempts to analyze whether the intensity of endurance training can reach a level at which it becomes harmful to the health of athletes.&#x0D; Materials and methods:&#x0D; This article reviews the literature on the impact of physical activity on cardiovascular health, with particular emphasis on endurance training. Articles were searched by key words, e.g. endurance training, cardiovascular health, marathon, running, cycling in various configurations, in Pubmed, Medline, Google Scholar databases.&#x0D; Actual state of knowledge:&#x0D; Regular physical activity is commonly regarded as the best preventive factor for cardiovascular diseases. Intensive endurance training significantly increases the efficiency of the cardiovascular system. Despite the significant benefits of regular endurance training, scientific reports suggest that athletes practicing this type of activity are more prone to developing certain cardiovascular disorders, such as coronary heart disease, atrial fibrillation, sinus bradycardia, and myocardial fibrosis.&#x0D; Colclusion:&#x0D; Regular and moderate aerobic physical activity is key to maintain optimal health. Endurance athletes develop a series of adaptations in the cardiovascular system, exhibit greater survival rates, and are less likely to experience sudden cardiac death compared to those who do not engage in regular physical activity. There is evidence suggesting a higher incidence of certain cardiovascular complications compared to healthy individuals who do not engage in sports. The reasons for these changes and their impact should be the subject of further research.

Atrial Fibrillation in Endurance Training Athletes: Scoping Review.

Moderate regular physical activity is indicated to avoid atrial fibrillation (AF), whereas athletes should be counseled that long-lasting vigorous sports engagement may cause AF, according to the 2016 European Society of Cardiology (ESC) recommendations for AF treatment. Exercise and AF are complex. To evaluate the relationship between Endurance training and AF, in addition to the starting point/trigger by which Endurance Training causes impairment of cardiac function and AF, considering the time and intensity of Endurance training. We synthesized evidence from articles published in the PubMed, EMBASE, and SciELO databases using their respective Boolean operators. A total of 112 original articles related to AF and endurance athletes published up to the year 2023 were reviewed. Our study verified multiples aspects of the genesis of AF in athletes, such as cardiac adaptations to exercise, disturbances in cardiac injury biomarkers, sex differences in cardiac adaptations and their role in AF risk, and the relationship between body composition (height, weight, and physical fitness) and AF pathogenesis. Variations in cardiac structure (increased atrial thickness and size in addition to myocardial fibrosis) and significant increases in vagal tone (sinus bradycardia and imbalances in sympathetic and parasympathetic activation) shorten the refractory period shortening in athletes, induce the onset of re-entrance mechanisms, and serve as ectopic triggers that can lead to AF.

Does Higher Intensity Increase the Rate of Responders to Endurance Training When Total Energy Expenditure Remains Constant? A Randomized Controlled Trial

BackgroundStandardized training prescriptions often result in large variation in training response with a substantial number of individuals that show little or no response at all. The present study examined whether the response in markers of cardiorespiratory fitness (CRF) to moderate intensity endurance training can be elevated by an increase in training intensity.MethodsThirty-one healthy, untrained participants (46 ± 8 years, BMI 25.4 ± 3.3 kg m−2 and {dot{text{V}}}O2max 34 ± 4 mL min−1 kg−1) trained for 10 weeks with moderate intensity (3 day week−1 for 50 min per session at 55% HRreserve). Hereafter, the allocation into two groups was performed by stratified randomization for age, gender and VO2max response. CON (continuous moderate intensity) trained for another 16 weeks at moderate intensity, INC (increased intensity) trained energy-equivalent for 8 weeks at 70% HRreserve and then performed high-intensity interval training (4 × 4) for another 8 weeks. Responders were identified as participants with VO2max increase above the technical measurement error.ResultsThere was a significant difference in {dot{text{V}}}O2max response between INC (3.4 ± 2.7 mL kg−1 min−1) and CON (0.4 ± 2.9 mL kg−1 min−1) after 26 weeks of training (P = 0.020). After 10 weeks of moderate training, in total 16 of 31 participants were classified as VO2max responders (52%). After another 16 weeks continuous moderate intensity training, no further increase of responders was observed in CON. In contrast, the energy equivalent training with increasing training intensity in INC significantly (P = 0.031) increased the number of responders to 13 of 15 (87%). The energy equivalent higher training intensities increased the rate of responders more effectively than continued moderate training intensities (P = 0.012).ConclusionHigh-intensity interval training increases the rate of response in VO2max to endurance training even when the total energy expenditure is held constant. Maintaining moderate endurance training intensities might not be the best choice to optimize training gains.Trial Registration German Clinical Trials Register, DRKS00031445, Registered 08 March 2023—Retrospectively registered, https://www.drks.de/DRKS00031445

Restricted nasal-only breathing during self-selected low intensity training does not affect training intensity distribution.

Introduction: Low-intensity endurance training is frequently performed at gradually higher training intensities than intended, resulting in a shift towards threshold training. By restricting oral breathing and only allowing for nasal breathing this shift might be reduced. Methods: Nineteen physically healthy adults (3 females, age: 26.5 ± 5.1years; height: 1.77 ± 0.08m; body mass: 77.3 ± 11.4kg; VO2peak: 53.4 ± 6.6mL·kg-1min-1) performed 60min of self-selected, similar (144.7 ± 56.3 vs. 147.0 ± 54.2 W, p = 0.60) low-intensity cycling with breathing restriction (nasal-only breathing) and without restrictions (oro-nasal breathing). During these sessions heart rate, respiratory gas exchange data and power output data were recorded continuously. Results: Total ventilation (p < 0.001, ηp 2 = 0.45), carbon dioxide release (p = 0.02, ηp 2 = 0.28), oxygen uptake (p = 0.03, ηp 2 = 0.23), and breathing frequency (p = 0.01, ηp 2 = 0.35) were lower during nasal-only breathing. Furthermore, lower capillary blood lactate concentrations were found towards the end of the training session during nasal-only breathing (time x condition-interaction effect: p = 0.02, ηp 2 = 0.17). Even though discomfort was rated marginally higher during nasal-only breathing (p = 0.03, ηp 2 = 0.24), ratings of perceived effort did not differ between the two conditions (p ≥ 0.06, ηp 2 = 0.01). No significant "condition" differences were found for intensity distribution (time spent in training zone quantified by power output and heart rate) (p ≥ 0.24, ηp 2 ≤ 0.07). Conclusion: Nasal-only breathing seems to be associated with possible physiological changes that may help to maintain physical health in endurance athletes during low intensity endurance training. However, it did not prevent participants from performing low-intensity training at higher intensities than intended. Longitudinal studies are warranted to evaluate longitudinal responses of changes in breathing patterns.

The effect of jujube extract consumption during two types of high intensity interval training and intensive endurance training on oxidative stress and antioxidant indices of liver tissue in immature male Wistar rats

زمینه و هدف: یکی از راهکارهای مناسب برای محافظت در برابر تأثیرات نامطلوب فشار اکسایشی ناشی از تمرینات ورزشی طولانی‌مدت و شدید، به‌کارگیری تدابیر تغذیه‌ای سالم و استفاده از مکمل‌های ضداکسایشی است. هدف این پژوهش بررسی اثر مصرف عصارة عناب طی دو نوع تمرین تناوبی و استقامتی شدید بر شاخص‌های ضداکسایشی و فشار اکسایشی بافت کبد موش‌های صحرایی نابالغ نر بود.مواد و روش‌ها: 72 سر موش نابالغ صحرایی نژاد ویستار با سن 22 روز و میانگین وزنی 475/7 ± 64/60 گرم پس از وزن‌کشی به‌صورت تصادفی به نه گروه کنترل، تمرین تناوبی شدید (HIT)، تمرین استقامتی شدید (ICT)، عناب، ICT + عناب، ICT + دارونما، HIT + دارونما، HIT + عناب و دارونما تقسیم شدند. پس از یک هفته آشناسازی عمومی و اختصاصی، برنامة تمرین استقامتی شدید شامل دویدن روی نوار گردان به مدت چهار هفته (پنج جلسه در هفته) با مدت و شدت پیش‌رونده و با رعایت اصل اضافه‌بار تمرین اجرا شد. به‌طوری‌که سرعت در هفتة اول برابر 10 تا 18 متر در دقیقه و مدت آن 10-30 دقیقه بود و در هفتة آخر سرعت تمرین به 30 متر بر دقیقه و مدت آن 55-60 رسید. برنامة تمرینی HITنیز در قالب تمرین با الگوی دوره‌های هفت‌روزه (شش روز تمرین و یک روز استراحت به‌منظور جلوگیری از بیش‌تمرینی) انجام گرفت. بر اساس اصل اضافه‌بار تمرین به‌گونه‌ای اعمال شد که سرعت تمرین در هفتة آشناسازی برابر با 10-16 متر در دقیقه و مدت آن یک دقیقه بود و در هفتة آخر سرعت تمرین 36-40 متر در دقیقه (معادل حدود 85% Vo2max) رسید. به گروه‌های دارونما، گاواژ آب مقطر و به گروه‌های دارای عناب، گاواژ عصارة عناب با دوز 600 میلی‌گرم به ازای هر کیلوگرم وزن بدن هر موش، روزانه پس از تمرین ارائه شد. اندازه‌گیری میزان فعالیت آنزیم‌های SOD ، GPX و CAT و سطوح MDA و TAC بافت کبد به روش اسپکتروفتومتری و کیت الایزا انجام گرفت. برای تجزیه‌وتحلیل داده‌ها از روش‌های آماری آنوا و آزمون تعقیبی توکی استفاده شد.نتایج: نتایج نشان داد که فعالیت استقامتی شدید و HIT موجب کاهش معنادار میزان MDA شد (05/0P<). هرچند بر میزان فعالیت آنزیم‌های ضداکسایشی SOD، GPX و سطوح TAC تأثیر معناداری نداشت (05/0P>). از سویی، تمرین HIT موجب افزایش معنادار آنزیم CAT شد (05/0P<). در گروه‌های دارای گاواژ عناب، تأثیر معناداری بر میزان آنزیم‌های ضداکسایشی SOD، GPX، CAT، TAC و MDA نداشتند (05/0P>).نتیجه‌گیری: به‌نظر می‌رسد که تمرینات استقامتی شدید و HIT موجب تعدیل شاخص‌های اکسایشی و همچنین تمرین HIT، سبب بهبود نشانگر ضداکسایشی CAT در موش‌های نابالغ می‌شود.

Durability is improved by both low and high intensity endurance training.

Introduction: This is one of the first intervention studies to examine how low- (LIT) and high-intensity endurance training (HIT) affect durability, defined as 'time of onset and magnitude of deterioration in physiological-profiling characteristics over time during prolonged exercise'. Methods: Sedentary and recreationally active men (n = 16) and women (n = 19) completed either LIT (average weekly training time 6.8 0.7h) or HIT (1.6 0.2h) cycling for 10 weeks. Durability was analyzed before and after the training period from three factors during 3-h cycling at 48% of pretraining maximal oxygen uptake (VO2max): 1) by the magnitude and 2) onset of drifts (i.e. gradual change in energy expenditure, heart rate, rate of perceived exertion, ventilation, left ventricular ejection time, and stroke volume), 3) by the 'physiological strain', defined to be the absolute responses of heart rate and its variability, lactate, and rate of perceived exertion. Results: When all three factors were averaged the durability was improved similarly (time x group p = 0.42) in both groups (LIT: p = 0.03, g = 0.49; HIT: p = 0.01, g = 0.62). In the LIT group, magnitude of average of drifts and their onset did not reach statistically significance level of p < 0.05 (magnitude: 7.7 6.8% vs. 6.3 6.0%, p = 0.09, g = 0.27; onset: 106 57min vs. 131 59 min, p = 0.08, g = 0.58), while averaged physiological strain improved (p = 0.01, g = 0.60). In HIT, both magnitude and onset decreased (magnitude: 8.8 7.9% vs. 5.4 6.7%, p = 0.03, g = 0.49; onset: 108 54min vs. 137 57 min, p = 0.03, g = 0.61), and physiological strain improved (p = 0.005, g = 0.78). VO2max increased only after HIT (time x group p < 0.001, g = 1.51). Conclusion: Durability improved similarly by both LIT and HIT based on reduced physiological drifts, their postponed onsets, and changes in physiological strain. Despite durability enhanced among untrained people, a 10-week intervention did not alter drifts and their onsets in a large amount, even though it attenuated physiological strain.

Endurance Training with Moderate and Intense Intensity Along with the Consumption of Safflower Extract Improved the Oxidative Damage of Testicular Tissue Caused by Dexamethasone in Adult Male Rats

Background: Chronic use of dexamethasone, especially in athletes, is associated with reproductive disorders. Objectives: This study aimed to investigate the effect of high and moderate intensity endurance training along with the consumption of safflower extract on testicular oxidative damage and testosterone level in male rats treated with dexamethasone. Methods: A total of 45 male Wistar rats were divided into the controlled and treated groups. Dexamethasone was subcutaneously injected for five days at a dose of 8 mg/kg. High and moderate intensity exercises were performed for ten weeks (five days a week) at speeds of 28 and 34 m/min, respectively, on the treadmill. The safflower seed extract (500 mg/kg of the body weight) was administered daily during the training period by gavage. At the end of the given period, testicular tissue sampling was performed to measure malondialdehyde, total antioxidant capacity, Nrf2, and testosterone levels. Results: The results showed that high and moderate intensity exercises along with the consumption of safflower seed extract (P = 0.000) as well as high intensity exercise alone (P = 0.04) caused a significant increase in Nrf2 expression in animals receiving dexamethasone compared to the dexamethasone group. No significant change was observed in the testosterone level of the dexamethasone group compared to that of the control group. However, a significant change was detected in its level in some groups treated with moderate exercise, intense exercise, and safflower extract. Conclusions: It was concluded that moderate and high intensity endurance training, along with the consumption of safflower extract, had the potential to prevent infertility caused by dexamethasone.

Preventive effects of intense continuous endurance training on isoproterenol-induced cardiac apoptosis and protein synthesis gene expression in wistar rats

Objectives: Heart failure contributes to cellular lesions and left ventricular dysfunction. The present study aimed to determine the effects of intense continuous endurance training on protein synthesis gene expression and prevention of isoproterenol-induced cardiac apoptosis.&#x0D; Methods: In this experimental study, 16 male Wistar rats were assigned to exercise and control groups. After eight-week treadmill running, with 15° inclination, at 65-75% of VO2max for 30-60 minutes, Isoproterenol (3 mg/kg) was injected into the rats subcutaneously for 7 days. And 24 hours after the last injection, the left ventricular tissue was stored at -80°C for qRT-PCR and TUNEL assay. Between-group differences were determined by parametric and non-parametric tests, using SPSS software version 24.&#x0D; Results: There was a significant increase in mTORC1 gene expression in the training group (P = 0.026) but AMPK alterations failed to be significant. eEF2K gene expression was suppressed in the training group (P = 0.001) which resulted in a significant increase in eEF2 expression (P = 0.005). Left ventricular weight and heart weight/body weight increased compared to the control group (P = 0.028, P = 0.010, respectively). And the training protocol effectively prevented the formation of isoproterenol-induced apoptotic cells (P &lt;0.001).&#x0D; Conclusions: The exercise training protocol increased protein synthesis gene expression, and improved cardiac protection by reducing apoptosis. This protocol can be considered a promising modality in preventing and reducing apoptosis induced by heart disease such as myocardial infarction.

Exploring Moderators of the Effect of High vs. Low-to-Moderate Intensity Exercise on Cardiorespiratory Fitness During Breast Cancer Treatment - Analyses of a Subsample From the Phys-Can RCT.

IntroductionThe results from the physical training and cancer randomized controlled trial (Phys-Can RCT) indicate that high intensity (HI) strength and endurance training during (neo-)adjuvant cancer treatment is more beneficial for cardiorespiratory fitness (CRF, measured as peak oxygen uptake [VO2peak]) than low-to-moderate intensity (LMI) exercise. Adherence to the exercise intervention and demographic or clinical characteristics of patients with breast cancer undergoing adjuvant treatment may moderate the exercise intervention effect on VO2peak. In this study, the objective was to investigate whether baseline values of VO2peak, body mass index (BMI), time spent in moderate- to vigorous-intensity physical activity (MVPA), physical fatigue, age, chemotherapy treatment, and the adherence to the endurance training moderated the effect of HI vs. LMI exercise on VO2peak.Materials and MethodsWe used data collected from a subsample from the Phys-Can RCT; women who were diagnosed with breast cancer and had a valid baseline and post-intervention VO2peak test were included (n = 255). The exercise interventions from the RCT included strength and endurance training at either LMI, which was continuous endurance training at 40–50% of heart rate reserve (HRR), or at HI, which was interval training at 80–90% of HRR, with similar exercise volume in the two groups. Linear regression analyses were used to investigate moderating effects using a significance level of p < 0.10. Statistically significant interactions were examined further using the Johnson–Neyman (J-N) technique and regions of significance (for continuous variables) or box plots with adjusted means of post-intervention VO2peak (for binary variables).ResultsAge, as a continuous variable, and adherence, dichotomized into < or > 58% based on median, moderated the effect of HI vs. LMI on CRF (B = −0.08, 95% CI [−0.16, 0.01], pinteraction = 0.06, and B = 1.63, 95% CI [−0.12, 3.38], pinteraction = 0.07, respectively). The J-N technique and regions of significance indicated that the intervention effect (HI vs. LMI) was positive and statistically significant in participants aged 61 years or older. Baseline measurement of CRF, MVPA, BMI, physical fatigue, and chemotherapy treatment did not significantly moderate the intervention effect on CRF.ConclusionWomen with breast cancer who are older and who have higher adherence to the exercise regimen may have larger effects of HI exercise during (neo-)adjuvant cancer treatment on CRF.

Road to Tokyo 2020 Olympic Games: Training Characteristics of a World Class Male Triathlete.

There is a growing interest in the scientific literature for reporting top-class endurance athletes training programs. This case study reports on the training program of a world-class male triathlete preparing to compete in the Tokyo 2020 Olympic Games. A macrocycle of 43 weeks is presented. The triathlete performed 14.74 ± 3.01 h of weekly endurance training volume. Training intensity distribution (TID) was 81.93% ± 6.74%/7.16% ± 2.03%/10.91% ± 6.90% for zones 1 (low intensity, <VT1), 2 (moderate intensity, VT1-VT2) and 3 (high intensity, >VT2) respectively. Pyramidal TID model is observed during the initial stages of the periodization and Polarized TID model is observed at the end of the macrocycle. The triathlete’s peak ⩒O2 was increased by 20% on cycling and by 14% on running. Peak power was increased by 3.13% on cycling test and peak speed by 9.71% on running test. Finally, the triathlete placed 12th in Olympic distance and 10th in Mixed Relay in Tokyo 2020 Olympic games.