High Volume Endurance Training Research Articles

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.

Body Composition, Fasting Blood Glucose and Lipidemic Indices Are Not Primarily Determined by the Nutritional Intake of Middle-Aged Endurance Trained Men-Another "Athletes' Paradox"?

Systematic, regular high-volume endurance training induces significant metabolic adaptations in glucose and lipids metabolism, which seems to affect the negative impact of unhealthy nutrition, at least in animal models. The present study aimed to investigate the main determinants of body composition, blood glucose and lipids concentrations between middle-aged sedentary individuals (Sed) and well-trained endurance athletes (Run), both following an unhealthy high-fat diet. In thirty-five Sed (Age: 54.0 ± 6.6 yrs, Body Mass: 77.1 ± 10.5 kg, BMI: 31.3 ± 6.0 kg·m−2) and thirty-six Run (Age: 51.6 ± 5.2 yrs, Body Mass: 85.8 ± 3.4 kg, BMI: 23.2 ± 1.8 kg·m−2), body composition, nutritional intake, energy expenditure, resting metabolic rate (RMR), respiratory exchange ratio (RER), and blood glucose and lipids concentrations were evaluated. Multiple linear regression analyses revealed that body composition, blood glucose and lipids’ concentrations in the Run group were primarily determined by the energy expenditure (B: −0.879 to −1.254), while in the Sed group, by their energy intake (B:−0.754 to 0.724). In conclusion, it seems that in well-trained endurance middle-aged athletes, body composition, blood glucose, and lipids concentrations seem to be determined by their training-induced daily energy expenditure and not by their nutritional intake per se. At the same time, nutrition is the primary determinant in aged-matched sedentary individuals, even if they both follow high-fat diets.

Stress-Induced Cardiometabolic Perturbations, Increased Oxidative Stress and ACE/ACE2 Imbalance are Improved by High-Volume Endurance Training in Rats

Stress-Induced Cardiometabolic Perturbations, Increased Oxidative Stress and ACE/ACE2 Imbalance are Improved by High-Volume Endurance Training in Rats

MTOR signaling-related microRNAs as cardiac hypertrophy modulators in high-volume endurance training.

Aerobic exercise training (ET) promotes cardiovascular adaptations, including physiological left ventricular hypertrophy (LVH). However, the molecular mechanisms underlying these changes are unclear. The study aimed to elucidate specific microRNAs (miRNAs) and target genes involved with the protein kinase B (Akt)/mammalian target of rapamycin (mTOR) signaling in high-volume ET-induced LVH. Eight-week-old female Wistar rats were assigned to three groups: sedentary control (SC), trained protocol 1 (P1), and trained protocol 2 (P2). P1 consisted of 60 min/day of swimming, 5 times/wk, for 10 wk. P2 consisted of the same protocol as P1 until the 8th week; in the 9th week rats trained 2 times/day, and in the 10th week they trained 3 times/day. Subsequently, structure and molecular parameters were evaluated in the heart. Trained groups demonstrate higher values of peak oxygen uptake ([Formula: see text]), exercise tolerance, and LVH in a volume-dependent manner. The miRNA-26a-5p levels were higher in P1 and P2 compared with the SC group (150 ± 15%, d = 1.8; 148 ± 16%, d = 1.7; and 100 ± 7%, respectively; P < 0.05). In contrast, miRNA-16-5p levels were lower in P1 and P2 compared with the SC group (69 ± 5%, d = 2.3, P < 0.01; 37 ± 4%, d = 5.6, P < 0.001; and 100 ± 6%, respectively). Additionally, miRNA-16-5p knockdown and miRNA-26a-5p overexpression significantly promoted cardiomyocyte hypertrophy in neonatal rat cardiomyocytes. Both miRNAs were selected, with the DIANA Tools bioinformatics website, for acting in the mTOR signaling pathway. The protein expression of AKT, MTOR, ribosomal protein S6 kinase beta-1 (P70S6K), and eukaryotic translation initiation factor 4E-binding protein 1 (4E-BP1) were greater in P1 and even more pronounced in P2. Nonetheless, glycogen synthase kinase 3 beta (GSK3β) protein expression was lower in trained groups. Together, these molecular changes may contribute to a pronounced physiological LVH observed in high-volume aerobic training.NEW & NOTEWORTHY Physiological hypertrophic growth of the heart as a compensatory response to exercise training (ET) is coupled with recent progress in dissecting the microRNA (miRNA)-mediated molecular basis of hypertrophy. Aerobic ET seems to reduce miRNA-16-5p and increase miRNA-26a-5p expression in a volume-dependent mode, activating protein kinase B (Akt)/mammalian target of rapamycin (mTOR) pathways, and likely produces an enhanced left ventricular hypertrophy (LVH) in high-volume endurance training. New insight into these mechanisms can be useful in understanding physiological LVH and how it might be harnessed as a therapeutic application.

Endothelial Vasodilation After a High-Volume Training Load and Tapered Training in Collegiate Female Swimmers

Weihl, FM and Van Guilder, GP. Endothelial vasodilation after a high-volume training load and tapered training in collegiate female swimmers. J Strength Cond Res 35(3): 811-818, 2021-High-volume endurance training loads have been linked to adverse remodeling of the heart and large arteries; yet, data on the vascular endothelial function are unclear. Moreover, although collegiate-level endurance athletes often perform high-volumes of vigorous endurance training and resistance training as part of their strength and conditioning programs, it is unknown whether they also experience vascular abnormalities, particularly changes in endothelial function. The aim of this study was to verify the impact of a high-volume training load phase followed by low-volume tapered training on endothelial vasodilator function in National Collegiate Athletic Association (NCAA) Division I competitive female swimmers. Microvascular endothelial vasodilation was assessed by pulse arterial tonometry that provides a reactive hyperemia index in 10 female NCAA Division 1 swimmers after 4 weeks of a high-volume training load, and subsequently, after 3 weeks of low-volume tapered training as part of preparation for annual conference championships. The reactive hyperemia index was calculated as the ratio of the pulse volume amplitude after 5 minutes of left-arm brachial artery ischemia to the baseline amplitude, divided by same ratio in the contralateral arm. The high-volume training load included a 4-week block of dual-day sessions (120 minutes per practice) consisting of vigorous intensity endurance and high-intensity interval/sprint swim training, coupled with 5K running, resistance training, and Olympic weightlifting. Tapered training consisted of 3 weeks of 3-5 swims per week at ∼50% V̇o2max for 60 minutes per practice (∼4,000 minutes per practice). The reactive hyperemia index (1.73 ± 0.50) was low in athletes after the high-volume training load with 8 athletes demonstrating endothelial dysfunction. However, after tapered training, the reactive hyperemia index was ∼33% higher (2.29 ± 0.43; 95% confidence interval [CI]: 1.98-2.60, p = 0.0223 vs. the high-volume training load). Effect size, as expressed by the partial eta2 (0.46) and Cohen's dz (1.1923; 95% CI: 0.1687-2.4643) with tapered training, was large. These results demonstrate distinct differences in endothelial vasodilation after 4 weeks of a high-volume training load compared with a 3-week taper in NCAA Division I female swimmers.

The Benefits of High-Intensity Functional Training Fitness Programs for Military Personnel.

High intensity functional training (HIFT) programs are designed to address multiple fitness domains, potentially providing improved physical and mental readiness in a changing operational environment. Programs consistent with HIFT principals such as CrossFit, SEALFIT and the US Marine Corps' High Intensity Tactical Training (HITT) are increasingly popular among military personnel. The goal of HIFT programs is to produce high levels of cardiorespiratory fitness, endurance and strength that exceed those achieved by following current physical activity recommendations. Given the investment in and popularity of HIFT in the military, it is important to consider the potential impact of this approach to fitness training for the health of military personnel and their risk of training injury. In a previous report in this journal, we addressed the question of whether HIFT was associated with higher injury rates compared to other exercise programs. We argued that concerns about the injury potential of HIFT exercise programs were not supported by the scientific literature to date, although additional research was needed to directly compare injury rates in approaches such as CrossFit to traditional military fitness programs. In this article we will review the scientific data on the practical, health and fitness benefits of HIFT exercise programs for military populations. Practical benefits to HIFT exercise programs include shorter training times and volumes, exercises which simulate combat tasks, lower equipment costs, reduced potential for boredom and adaptation as a result of constant variation, less injury potential compared to high volume endurance training, and scalability to all fitness levels and rehabilitation needs. For instance, HIFT training volumes are typically between 25% to nearly 80% less than traditional military fitness programs without reductions in fitness outcomes. HIFT program also provide an impressive range of health benefits such as the promotion of metabolic conditioning and muscular strength, less systemic inflammation or oxidative damage compared to sustained aerobic activity, and promoting general physical preparedness (GPP) for the unpredictable physical demands of combat. Given the unique benefits of HIFT, we recommend that these programs become the standard for military physical training. Despite the promise of HIFT fitness programs, questions remain about implementing these programs in the military context. For instance, no large scale randomized trials comparing traditional military physical training with HIFT programs on both health and injury outcomes have been conducted. Such a trial could identify key elements from both types of programs which should be incorporated in future approaches to military fitness training. Also, research regarding the optimal ways of implementing HIFT to maximize both GPP and combat oriented physical skills is lacking. It is likely that an approach to HIFT training which promotes GPP for all personnel along with specialized elements selected on the basis of individual occupation demands would be maximally disseminable in the military.

Short-term moderate intensive high volume training program provides aerobic endurance benefit in wheelchair basketball players.

The aim of this paper was to investigate the effect of short-term period, moderate intensity and high volume endurance training on physiological variables in elite wheelchair basketball players. Eight wheelchair basketball players were examined. The subjects participated in a two-week intervention program of mainly two training types: wheelchair basketball and wheelchair driving endurance training. The subjects performed the continuously increasing cycling exercise (CCE) at the constant 60 rpm arm cranking speed at the beginning of the program and after two weeks of the program. The initial workload was 20 W, then the workload was increased by 2 W every 5 seconds until fatigue. The post training of the wheelchair basketball group in the study showed a significant improvement in the peak oxygen uptake (VO2peak) and the peak power output (POpeak). VO2peak increased by 9% from 2.32±0.16 L/min to 2.53±0.2 L/min (P<0.05). POpeak increased by 28% from 141.75±14.23 W, to 181.63±26.3 W (P<0.05). The pre-training and post training test power output (PO [w]), relative power output (PO [w/kg]) increased significantly in all zones of energy production. In conclusion, this study indicated that the wheelchair basketball squad had relatively high levels of aerobic fitness prior to participating in the endurance training program. Nevertheless, the high-volume, moderate-intensity, short-term training program, which evolved over the two-weeks period, resulted in the improvement of the athlete's aerobic endurance. The ventilatory threshold (VT) and the second ventilatory threshold (VT2) are good markers for aerobic capacity of wheelchair athletes.

Nutrition for Training and Performance

The human body is designed for movement and capable of incredible athletic and sporting achievements. Attempts to improve the ability to perform on the athletic stage are never-ending and involve a serious dedication to training. Athletes, coaches, support personnel, and scientists are constantly experimenting with new ways to improve training and its applicability to performance. Nutrition is clearly a major factor in the success of training and performance as fuel is needed to power the human engine. The amount, type, and timing of nutritional intake play a large role in the physical and mental success of the athlete. In addition, nutritional intake also influences the adaptation to training and the recovery from training, to positively impact performance. The Gatorade Sports Science Institute (GSSI) brought together researchers for a meeting in February 2013 to discuss the recent evidence that nutrition influences athletic training and performance. Following the meeting, the authors were asked to summarize the recent work in their research area, resulting in the manuscripts in this Sports Medicine supplement. A major step forward in sports nutrition has been the ability to more thoroughly understand how training alters the body at the molecular level, in both acute and chronic situations. Various forms of training have been shown to activate cell signalling pathways that ultimately produce protein-specific adaptations geared to improving sport-specific performance. Whether engaging in classic moderate intensity–high volume endurance training, high intensity intermittent–low volume training, or resistance training, the body remodels to more aptly handle the specific physical stress. Nutrition is at the core of these adaptations through the provision of fuel and by shaping the adaptations. Concurrent training has long been of interest, where both resistance and endurance training sessions are completed over the course of a week or even on the same day. Engaging in high intensity intermittent–low volume training as compared with the classic moderate intensity–high volume endurance training has also been a central theme in the past few years. What can be achieved in these situations? Does the stimulus from one form of training dominate the other—and is one form of training more time efficient than the other? A related issue, especially in the case of high-end athletes, is monitoring training load and understanding when an athlete is overloaded and likely to underperform. What are the measures that athletes, trainers, therapists, coaches, nutritionists, and physiologists can use to accurately assess the situation? On the other side of the movement spectrum, what happens when muscles are not used either through injury or a sedentary lifestyle? Can nutrition in the form of antioxidants prevent the negative consequences associated with these situations? Serious athletes do all they can to maximize their physical and mental training, nutrition, recovery, and sleep quality. Once this has been achieved, are there nutritional means to acutely and chronically improve their training and performance with supplements like caffeine, creatine and buffering agents? In certain sports and athletic endeavours, losing a small amount of body mass without compromising training and performance can lead to improved performance. Can manipulating dietary protein intake aid in this pursuit and has this been thoroughly studied? Lastly, it is clear that athleticism and the pursuit of training and performance is no longer solely the domain of the young. The number of older athletes is on the rise and the phrase, “60 is the new 45” is commonly heard among active older individuals. What are the nutritional needs of this group of people and what needs to be studied to answer this question? The role of sports nutrition and exercise is becoming increasingly linked with health and performance and understanding the interactions between nutrition and exercise will help us to provide accurate information to exercisers and athletes.

The effect of heavy strength training on muscle mass and physical performance in elite cross country skiers

To investigate the effect of supplementing high-volume endurance training with heavy strength training on muscle adaptations and physical performance in elite cross country skiers. Eleven male (18-26 years) and eight female (18-27 years) were assigned to either a strength group (STR) (n=9) or a control group (CON) (n=10). STR performed strength training twice a week for 12 weeks in addition to their normal endurance training. STR improved 1 repetition maximum (RM) for seated pull-down and half squat (19 ± 2% and 12 ± 2%, respectively), while no change was observed in CON. Cross-sectional area (CSA) increased in m. triceps brachii for both STR and CON, while there was no change in the m. quadriceps CSA. VO(2max) during skate-rollerskiing increased in STR (7 ± 1%), while VO(2max) during running was unchanged. No change was observed in energy consumption during rollerskiing at submaximal intensities. Double-poling performance improved more for STR than for CON. Both groups showed a similar improvement in rollerski time-trial performance. In conclusion, 12 weeks of supplemental heavy strength training improved the strength in leg and upper body muscles, but had little effect on the muscle CSA in thigh muscles. The supplemental strength training improved both VO(2max) during skate-rollerskiing and double-poling performance.

Blood Lactate Diagnostics in Exercise Testing and Training

A link between lactate and muscular exercise was seen already more than 200 years ago. The blood lactate concentration (BLC) is sensitive to changes in exercise intensity and duration. Multiple BLC threshold concepts define different points on the BLC power curve during various tests with increasing power (INCP). The INCP test results are affected by the increase in power over time. The maximal lactate steady state (MLSS) is measured during a series of prolonged constant power (CP) tests. It detects the highest aerobic power without metabolic energy from continuing net lactate production, which is usually sustainable for 30 to 60 min. BLC threshold and MLSS power are highly correlated with the maximum aerobic power and athletic endurance performance. The idea that training at threshold intensity is particularly effective has no evidence. Three BLC-orientated intensity domains have been established: (1) training up to an intensity at which the BLC clearly exceeds resting BLC, light- and moderate-intensity training focusing on active regeneration or high-volume endurance training (Intensity < Threshold); (2) heavy endurance training at work rates up to MLSS intensity (Threshold ≤ Intensity ≤ MLSS); and (3) severe exercise intensity training between MLSS and maximum oxygen uptake intensity mostly organized as interval and tempo work (Intensity > MLSS). High-performance endurance athletes combining very high training volume with high aerobic power dedicate 70 to 90% of their training to intensity domain 1 (Intensity < Threshold) in order to keep glycogen homeostasis within sustainable limits.

Effects of acid–base balance and high or low intensity exercise on VEGF and bFGF

The purpose of the present study was to compare the acute hormonal response to a short-term high-intensity training (HIT) versus a high-volume endurance training (HVT) and to investigate the effects of acid-base status on cytokines involved in angiogenesis (VEGF and bFGF). Eleven subjects participated in three experimental trials. Two times subjects performed four 30-s "all-out" exercise bouts on a cycle ergometer separated by 5-min rest each, at which subjects either received bicarbonate (HIT (B)) or a placebo (HIT (P)) before the exercise. The third exercise trail consisted of a constant load exercise for 1 h at 50% peak power output (PPO). Venous blood samples were taken under resting conditions, 10, 60, and 240 min after each exercise condition to determine VEGF and bFGF serum concentrations. Capillary blood samples were taken to determine lactate concentrations and blood gas parameters. Mean pH values were significantly higher during HIT (B) compared to HIT (P). Serum VEGF concentration was significantly increased 10-min post-exercise in both HIT interventions. HVT showed no significant effects on VEGF levels. The diminished acidosis during HIT (B) had no effects on the VEGF response. There were no significant changes in bFGF in response to HIT or HVT. The present study suggests that HIT is a stimulus for exercise-induced VEGF secretion. These findings might be relevant for the arrangement of training, due to the fact that most of the training is often performed at low intensities possibly leading to an insufficient stimulus for VEGF secretion and angiogenesis.

Short-Term High-Intensity Interval Training Reduces Hyperglycemia in Type 2 Diabetics

Glycemic regulation is impaired in individuals with type 2 diabetes (T2D). Current guidelines recommend that people with T2D should participate in a cumulative total of 150 minutes of continuous, moderate-intensity aerobic exercise each week, or at least 90 minutes of vigorous intensity exercise. While effective for improving glycemic control, most individuals with T2D do not perform sufficient activity to achieve health benefits, often citing "lack of time" as a key barrier to regular exercise participation. Low-volume high-intensity interval training (HIT) is a potent stimulus for inducing metabolic adaptations typically associated with traditional high-volume endurance training. However, the effects of low-volume HIT on glycemic control in people with T2D is currently unknown. PURPOSE: To determine the utility of HIT to reduce hyperglycemia in patients with T2D in a practical, time-efficient manner. METHODS: 7 subjects with T2D (age: 62 ± 3 yr, BMI: 33 ± 3.8 kg/m2, Wmax: 125 ± 18 W) performed 6 training sessions over 2 wk. Each session consisted of 10 × 1 min cycling efforts at ∼90% Wmax elicited during a ramp VO2peak test, interspersed with 1 min of rest (113 ± 11 W). Continuous Glucose Monitoring (CGM) technology (Medtronic CGMS® iPro Recorder) was employed under standard dietary conditions for a 24 hr period on a pre-training control day and ∼48-72 hr following the final training session. RESULTS: CGM data revealed lower mean 24 hr blood glucose concentration following HIT (7.6 ± 0.5 mmol/L vs. 6.6 ± 0.3 mmol/L, p < 0.05). The sum of the 3 hr postprandial area under the glucose curve for breakfast, lunch and dinner was also reduced following training (689 ± 196 mmol/L × 9hr vs. 991 ± 214 mmol/L × 9hr, p < 0.05). CONCLUSIONS: These preliminary data shed light on the potential for low-volume HIT to represent a unique, time-efficient exercise strategy to improve glycemic regulation in people with T2D. Supported by the Canadian Diabetes Association

Effect of high- and low-intensity exercise and metabolic acidosis on levels of GH, IGF-I, IGFBP-3 and cortisol

Objective The purpose of the present study was to examine the acute hormonal response of a short term high-intensity training (HIT) versus a high volume endurance training (HVT) and to determine the contribution of the metabolic acidosis as a stimulus for possibly different reactions of circulating hGH, IGF-1, IGFBP-3 and cortisol. Design Eleven subjects participated in three experimental trials separated by one week. Two times subjects performed four 30 s maximal effort exercise bouts on a cycle ergometer separated by 5 min rest each. Before the exercise subjects either received (single-blinded) bicarbonate (HIT (B)) or a placebo (HIT (P)). The third exercise trail consisted of a constant load exercise for 1 h at 50% VO 2max (HVT). Venous blood samples were taken under resting conditions, 10 min, 60 min and 240 min after each exercise condition to determine hGH, IGF-1, IGFBP-3 and cortisol serum concentrations. Capillary blood samples were taken to determine lactate concentrations and blood gas parameters. Results Power output, mean lactate concentrations and mean pH values were significantly higher during HIT (B) compared to HIT (P). Serum cortisol and hGH concentrations were significantly increased 10 min post exercise in both HIT interventions. IGFBP-3 was only significantly increased after HIT (P), whereas IGF-1 was not affected by any of the interventions. HVT showed no significant effects on cortisol, hGH, IGF-1 and IGFBP-3 levels. Additionally it was shown that the diminished acidosis during HIT (B) attenuates the cortisol and hGH response. Conclusions The present study suggests that HIT/acidosis is a stimulus for exercise-induced cortisol/hGH secretion, but not for IGF-1 and IGFBP-3 under these experimental conditions. These findings might be relevant for arrangements of interval training, due to the fact that active or passive recovery during rest periods influence the acid base status and may therefore influence the hormonal response.

Behavior of Testosterone and Cortisol During an Intensity-Controlled High-Volume Training Period Measured by a Training Task-Specific Test in Men Rowers

The aim of this study was to investigate changes in the stress hormones testosterone and cortisol after a task-specific exercise during a high-volume endurance training cycle in men rowers. Eight highly trained men rowers were investigated during a high-volume, low-intensity training period. A 2-hour, low-intensity, long-distance rowing (LDT) test was conducted at baseline, after a high-volume period, and after the recovery period. Training and performance intensities were obtained at the graded incremental test, were preset individually, and were the same during all LDTs. Fasting blood samples were taken during the same days as the LDTs. Exercise-induced blood samples were taken before, 5 minutes after, and 30 minutes after (post 30') the completion of each LDT. There were no significant changes in fasting cortisol and testosterone values during the whole study period, and there were no significant changes in cortisol and testosterone concentrations during the LDT. However, testosterone concentration was significantly decreased at post 30' compared with posttest values during the second LDT that was held after the 2-week high-training-volume period, and, during the second LDT, post 30' values of cortisol tended to be decreased compared with posttest values (p = 0.063). In conclusion, changes in the concentrations of testosterone and cortisol after long-distance rowing indicate decreased adaptivity after the training-specific performance test.

Sprint interval and traditional endurance training induce similar improvements in peripheral arterial stiffness and flow-mediated dilation in healthy humans

Low-volume sprint interval training (SIT), or repeated sessions of brief, intense intermittent exercise, elicits metabolic adaptations that resemble traditional high-volume endurance training (ET). The effects of these different forms of exercise training on vascular structure and function remain largely unexplored. To test the hypothesis that SIT and ET would similarly improve peripheral artery distensibility and endothelial function and central artery distensibility, we recruited 20 healthy untrained subjects (age: 23.3 +/- 2.8 yr) and had them perform 6 wk of SIT or ET (n = 5 men and 5 women per group). The SIT group completed four to six 30-s "all-out" Wingate tests separated by 4.5 min of recovery 3 days/wk. The ET group completed 40-60 min of cycling at 65% of their peak oxygen uptake (Vo2peak) 5 days/wk. Popliteal endothelial function, both relative and normalized to shear stimulus, was improved after training in both groups (main effect for time, P < 0.05). Carotid artery distensibility was not statistically altered by training (P = 0.29) in either group; however, popliteal artery distensibility was improved in both groups to the same degree (main effect, P < 0.05). We conclude that SIT is a time-efficient strategy to elicit improvements in peripheral vascular structure and function that are comparable to ET. However, alterations in central artery distensibility may require a longer training stimuli and/or greater initial vascular stiffness than observed in this group of healthy subjects.

Skeletal muscle pathology in endurance athletes with acquired training intolerance

Background: It is well established that prolonged, exhaustive endurance exercise is capable of inducing skeletal muscle damage and temporary impairment of muscle function. Although skeletal muscle has a remarkable capacity...

Influence of seasonal variations in training loads on selected amino acids and parameters of the psychoimmunological network in a swimming team.

In the last years a shift in amino acid profile was discussed as one reason for the development of staleness. Signs of staleness are among others susceptibility to infection and disturbances in well-being. Beside tryptophane and branched-chain amino acids (BCAA) glutamine is the most discussed amino acid (AA) in this context. Based on the hypothesis of a multifactorial genesis of staleness and these AA being the metabolic link in psychoimmunology, seven young swimmers of regional top level were examined in a longitudinal field monitoring for biochemical, biomechanical and psycho-physiological data at six different training phases across one year. Special interest was spent on phases with the highest training loads (HT I and II) because of the increased risk of appearance of staleness compared with the regeneration phase (RP). The results point out that well controlled and regulated HT does not reduce but increases the plasma levels of glutamate (means and SD; RP 20 +/- 8 micromol/l, HT I 34 +/- 11 micromol/l), glutamine (RP 489 +/- 155 micromol/l, HT I 634 +/- 113 micromol/l) and BCAA (valine RP 164 +/- 54 micro mol/l, HT I 283 +/- 58 micromol/l, isoleucine RP 59 +/- 20 micromol/l, HT I 101 +/- 24 micromol/l, leucine RP 88 +/- 32 micromol/l, HT I 142 +/- 35 micro mol/l). The immunological parameters did not show any significant training-induced changes (sIL-2-R: RP 422 +/- 98 U/ml, HT I 522 +/- 70 U/ml, s-ICAM: RP 157 +/- 11 ng/ml, HT I 185 +/- 32 ng/ml) and don't seem to be suitable as indicators for a "biochemical-psychophysiological" justified control and regulation of training. Possibly the increasing of plasma concentrations of AA by intensive and high volume endurance training is the "store shape" of AA in view of saving and provisioning the organism for further exhausting training loads.