Long-lasting Exercise Research Articles

Effects of L-Carnitine Intake on Exercise-Induced Muscle Damage and Oxidative Stress: A Narrative Scoping Review.

Exercise-induced muscle damage results in decreased physical performance that is accompanied by an inflammatory response in muscle tissue. The inflammation process occurs with the infiltration of phagocytes (neutrophils and macrophages) that play a key role in the repair and regeneration of muscle tissue. In this context, high intensity or long-lasting exercise results in the breakdown of cell structures. The removal of cellular debris is performed by infiltrated phagocytes, but with the release of free radicals as collateral products. L-carnitine is a key metabolite in cellular energy metabolism, but at the same time, it exerts antioxidant actions in the neuromuscular system. L-carnitine eliminates reactive oxygen and nitrogen species that, in excess, alter DNA, lipids and proteins, disturbing cell function. Supplementation using L-carnitine results in an increase in serum L-carnitine levels that correlates positively with the decrease in cell alterations induced by oxidative stress situations, such as hypoxia. The present narrative scoping review focuses on the critical evaluation of the efficacy of L-carnitine supplementation on exercise-induced muscle damage, particularly in postexercise inflammatory and oxidative damage. Although both concepts appear associated, only in two studies were evaluated together. In addition, other studies explored the effect of L-carnitine in perception of fatigue and delayed onset of muscle soreness. In view of the studies analyzed and considering the role of L-carnitine in muscle bioenergetics and its antioxidant potential, this supplement could help in postexercise recovery. However, further studies are needed to conclusively clarify the mechanisms underlying these protective effects.

Mechanisms and Severity of Exercise Intolerance Following COVID-19 and Similar Viral Infections: A Comparative Review.

Approximately 19% of the population is suffering from "Long COVID", also known as post-acute sequelae of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) (PASC), which often results in exercise intolerance. As COVID infections continue to be common, studying the long-term consequences of coronavirus disease (COVID) on physical function has become increasingly important. This narrative review will aim to summarize the current literature surrounding exercise intolerance following COVID infection in terms of mechanism, current management approaches, and comparison with similar conditionsand will aim to define limitations in the current literature. Multiple organ systems have been implicated in the onset of long-lasting exercise intolerance post-COVID, including cardiac impairment, endothelial dysfunction, decreased VO2 max and oxygen extraction, deconditioning due to bed rest, and fatigue. Treatment modalities for severe COVID have also been shown to cause myopathy and/or worsen deconditioning. Besides COVID-specific pathophysiology, general febrile illness as commonly experienced during infection will cause hypermetabolic muscle catabolism, impaired cooling, and dehydration, which acutely cause exercise intolerance. The mechanisms of exercise intolerance seen with PASC also appear similar to post-infectious fatigue syndrome and infectious mononucleosis. However, the severity and duration of the exercise intolerance seen with PASC is greater than that of any of the isolated mechanisms described above and thus is likely a combination of the proposed mechanisms. Physicians should consider post-infectious fatigue syndrome (PIFS), especially if fatigue persists after six months following COVID recovery. It is important for physicians, patients, and social systems to anticipate exercise intolerance lasting for weeks to months in patients with long COVID. These findings underscore the importance of long-term management of patients with COVID and the need for ongoing research to identify effective treatments for exercise intolerance in this population. By recognizing and addressing exercise intolerance in patients with long COVID, clinicians can provide proper supportive interventions, such as exercise programs, physical therapy, and mental health counseling, to improve patient outcomes.

Ultramarathon induces metabolite changes associated with the pathophysiology of cardiovascular diseases- in silico and in vivo analysis

Abstract Funding Acknowledgements Type of funding sources: Public grant(s) – National budget only. Main funding source(s): National Science Centre (NCN) and Internal source of Medical University of Warsaw. Introduction Regular physical exercise is analogous to improved cardiovascular health and increased longevity. However, if in excess it can act as a double edged sword. Acute bouts of extreme physical activity trigger complex molecular responses reflected by changes in inflammatory markers and metabolic pathways that are believed to yield detrimental effects on the cardiovascular system (CVS)[1]. Purpose We aimed to assess the effects of high-intensity and long-lasting exercise prototype (100km run) on the metabolomic changes in a unique population of high-level long-term ultra-marathon runners. Methods Plasma samples were collected from ultramarathon runners (n=22) with 2-time points: before and after the run (Completion (100 km) or exhaustion (52 - 91 km, median 74 km)). For untargeted metabolomic analysis we used ultra-high resolution Fourier-Transform Ion Cyclotron Resonance Mass Spectrometry with an electrospray ion source in direct injection. Mass spectra were analyzed by T-Rex2D algorithm in the MetaboScape5.0. Identified compounds were ontologically analyzed using MetaboAnalystR. MetscapeCytoscape plugin was used for metabolite-gene interaction analysis and gene lists were obtained from Biomart and DisGeNet. Results Mann-Whitney test (FDR<0.05) identified 1601 up and 1030 downregulated metabolites with a at least 2 fold of difference after high-intensity run. Enrichment analysis showed that the top pathways affected by analyzed metabolites were the TCA cycle (FDR=0.0442), metabolism of; Sphingolipids (p=0.00774), Glyoxylate and dicarboxylate (p=0.0249) and Butanoate (p=0.0352). Top disease phenotypes associated with differentially regulated metabolites were critical illness (major trauma, severe septic shock, or cardiogenic shock) (p=0.00154) and multiple CVS-related diseases (Fig1). Top after the run up-regulated metabolites identified in the study included heart failure associated acetylcarnitines[2] CAR(14:2) (log2FC=11.57; AUC=0.97), Dodecanoylcarnitine (2.00;0.960), 9-Decenoylcarnitine (1.78;0.95), CAR(DC8:0) (14.99;0.94), but also 2-Carboxy-5,7-dimethyl-4-octanolide (8.04;0.98), Methylmalonic acid (9.33;0.96) and cardiotoxic Cyclophosphamide (16.29;0.940)[3]. Top down-regulated metabolites after the run included potentially cardio-protective Gamma Glutamylglutamic acid (log2FC=-1.81; AUC=0.85), Fructose 1,6-bisphosphate (-2.42;0.88)[4], Oleamide (-1.82;0.86) and gamma-Glutamylglycine (-7.98;0.85). Interaction network analysis focused on genes associated with CVS identified atherosclerosis/ obesity-related Phospholipase A2 Group IB (PLA2G1B) as potentially the most affected gene by analyzed metabolites (Fig2). Conclusion Results show a twofold post run increase in metabolites that are both potential markers for acute exercise and that are strongly associated with CV diseases. This calls for consideration of the detrimental effects of excessive exercise and implementation of monitoring in amateur athletes.

Long-term efficacy of exercise across diagnostically heterogenous mental disorders and the mediating role of affect regulation skills

BackgroundExercise interventions are efficacious in reducing disorder-specific symptoms in various mental disorders. However, little is known about long-term transdiagnostic efficacy of exercise across heterogenous mental disorders and the potential mechanisms underlying treatment effects. MethodsPhysically inactive outpatients, with depressive disorders, anxiety disorders, insomnia or attention deficit hyperactivity disorder were randomized to a standardized 12-week exercise intervention, combining moderate exercise with behavior change techniques (BCTs) (n = 38), or a passive control group (n = 36). Primary outcome was global symptom severity (Symptom Checklist-90, SCL-90-R) and secondary outcomes were self-reported exercise (Physical Activity, Exercise, and Sport Questionnaire), exercise-specific affect regulation (Physical Activity-related Health Competence Questionnaire) and depression (SCL-90-R) assessed at baseline (T1), post-treatment (T2) and one year after post-treatment (T3). Intention-to-treat analyses were conducted using linear mixed models and structural equations modeling. ResultsFrom T1 to T3, the intervention group significantly improved on global symptom severity (d = −0.43, p = .031), depression among a depressed subsample (d = −0.62, p = .014), exercise (d = 0.45, p = .011) and exercise-specific affect regulation (d = 0.44, p = .028) relative to the control group. The intervention group was more likely to reveal clinically significant changes from T1 to T3 (p = .033). Increases in exercise-specific affect regulation mediated intervention effects on global symptom severity (ß = −0.28, p = .037) and clinically significant changes (ß = −0.24, p = .042). ConclusionsThe exercise intervention showed long-term efficacy among a diagnostically heterogeneous outpatient sample and led to long-lasting exercise behavior change. Long-term increases in exercise-specific affect regulation within exercise interventions seem to be essential for long-lasting symptom reduction.

The effect of diurnal variation on the performance of exhaustive continuous and alternated-intensity cycling exercises.

The purpose of this study was to explore the effect of time of day (TD) on two types of exercise protocols [continuous (CP) versus alternated (AP)]. Eleven physical education students (mean ± SD: age = 24.4 ± 1.2 years, aerobic peak power (APP) = 290 ± 31.9 W) underwent four sessions. These sessions were performed at 08:00 (AM) and 18:00 (PM) and consisted of cycling exercises until voluntary exhaustion at 90% APP (CP) or 70%-105% APP (AP) with the order of testing randomly assigned. Time to exhaustion (time limit = Tlim) was measured from the start of the test to when voluntary exhaustion occurred. Heart rate (HR) was recorded at baseline (HRbaseline) and throughout the protocols to determine HR at exhaustion (HRpeak). Blood lactate ([La]) was measured at rest, immediately after exhaustion and at 2min30 post-exercise to determine [La]peak. A significantly higher means of Tlim (334 ± 57 s; 272 ± 59 s; p< 0.05), HRbaseline (72 ± 5 beats/min; 67 ± 5 beats/min; p< 0.01), HRpeak (186 ± 8 beats/min; 178 ± 9 beats/min; p< 0.01) and [La]peak (16.2 ± 2.1 mmol/l; 13.9 ± 1.9 mmol/l; p< 0.05) were observed in CP at the PM compared to the AM. In addition, a significant higher means of Tlim (380 ± 54 s; 312 ± 82 s; p< 0.05), HRbaseline (73.1 ± 5.5 beats/min; 67 ± 5.4 beats/min; p< 0.01), HRpeak (186 ± 8 beats/min; 180 ± 9 beats/min; p< 0.05) and [La]peak (17.9 ± 1.8 mmol/l; 14.7 ± 2.1 mmol/l; p< 0.01) were observed in AP at the PM compared to the AM. It is concluded that AP and CP are more appropriate in the late afternoon than in the morning for performing long-lasting exercises. The AP could be a novel strategy for increasing the engagement in physical activity.

Long-lasting exercise involvement protects against decline in V̇O2max and V̇O2 kinetics in moderately active women.

We studied the effects of age on different physiological parameters, including those derived from (i) maximal cardiopulmonary exercise testing (CPET), (ii) moderate-intensity step transitions, and (iii) tensiomyography (TMG)-derived variables in moderately active women. Twenty-eight women (age, 19 to 53 years), completed 3 laboratory visits, including baseline data collection, TMG assessment, maximal oxygen uptake test via CPET, and a step-transition test from 20W to a moderate-intensity cycling power output (PO), corresponding to oxygen uptake at 90% gas exchange threshold. During the step transitions, breath-by-breath pulmonary oxygen uptake, near infrared spectroscopy derived muscle deoxygenation (ΔHHb), and beat-by-beat cardiovascular response were continuously monitored. There were no differences observed between the young and middle-aged women in their maximal oxygen uptake and peak PO, while the maximal heart rate (HR) was 12 bpm lower in middle-aged compared with young (p = 0.016) women. Also, no differences were observed between the age groups in τ pulmonary oxygen uptake, ΔHHb, and τHR during on-transients. The first regression model showed that age did not attenuate the maximal CPET capacity in the studied population (p = 0.638), while in the second model a faster τ pulmonary oxygen uptake, combined with shorter TMG-derived contraction time (Tc) of the vastus lateralis (VL), were associated with a higher maximal oxygen uptake (∼30% of explained variance, p = 0.039). In conclusion, long lasting exercise involvement protects against a maximal oxygen uptake and τpulmonary oxygen uptake deterioration in moderately active women. Novelty: Faster τ pulmonary oxygen uptake and shorter Tc of the VL explain 33% of the variance in superior maximal oxygen uptake attainment. No differences between age groups were found in τ pulmonary oxygen uptake, τΔHHb, and τHR during on-transients.

Swimming Training Attenuates Allodynia and Hyperalgesia Induced by Peripheral Nerve Injury in an Adult Male Rat Neuropathic Model: Effects on Irisin and GAD65.

The analgesic mechanism of long-lasting exercise on neuropathic pain is not well understood. This study explored the effects of swimming training on neuropathic pain and the expression of irisin, GAD65, and P2X3 after chronic constriction injury (CCI) of the sciatic nerve. Thirty-five male rats were randomly assigned to one of the following five groups: 1) no CCI or swimming (control); 2) swimming without CCI (SW); 3) swimming with CCI (CCISW); 4) CCI without swimming (CCI); and 5) sham CCI surgery (sham CCI). Behavioral responses to mechanical, cold, and heat stimuli were tested before and after CCI surgery, as well as each week throughout the four weeks of swimming training. The expression of irisin, GAD65, and P2X3 proteins in L4-L6 spinal cord segment, ipsilateral to the nerve injury, were evaluated by western blotting. Mechanical hyperalgesia was alleviated between the second and fourth weeks of training in the CCISW group. In the tactile allodynia and heat hyperalgesia tests, withdrawal thresholds of the CCISW group were significantly higher than the CCI group at the third and fourth week of training (P < 0.05), while cold allodynia showed delayed improvement occurring by the fourth week of training. The expression of irisin was lower in the CCISW and SW groups compared with the CCI group at day 33 post-CCI surgery. Moreover, CCI surgery significantly decreased the protein expression of GAD65 in L4-L6 spinal cord segments (P = 0.018), whereas swimming training prevented the decline of GAD65 in the CCISW group. Our findings showed that four weeks of swimming training produce beneficial rehabilitative effects on neuropathic pain symptoms. The analgesic effect of swimming training is partially related to the increase of GAD65. The beneficial role of irisin in neuropathic pain will require further investigation.

Strength training improves double-poling performance after prolonged submaximal exercise in cross-country skiers.

The purpose of this study was to investigate the effects of adding strength training with or without vibration to cross-country (XC) skiers' endurance training on double-poling (DP) performance, physiological, and kinematic adaptations. Twenty-one well-trained male XC-skiers combined endurance- and upper-body strength training three times per week, either with (n=11) or without (n=10) superimposed vibrations for 8weeks, whereas eight skiers performed endurance training only (CON). Testing included 1RM in upper-body exercises, work economy, neural activation, oxygen saturation in muscle, and DP kinematics during a prolonged submaximal DP roller ski test which was directly followed by a time to exhaustion (TTE) test. TTE was also performed in rested state, and the difference between the two TTE tests (TTEdiff ) determined the ability to maintain DP performance after prolonged exercise. Vibration induced no additional effect on strength or endurance gains. Therefore, the two strength training groups were pooled (STR, n=21). 1RM in STR increased more than in CON (P<.05), and there were no differences in changes between STR and CON in any measurements during prolonged submaximal DP. STR improved TTE following prolonged DP (20±16%, P<.001) and revealed a moderate effect size compared to CON (ES=0.80; P=.07). Furthermore, STR improved TTEdiff more than CON (P=.049). In conclusion, STR superiorly improved 1RM strength, DP performance following prolonged submaximal DP and TTEdiff , indicating a specific effect of improved strength on the ability to maintain performance after long-lasting exercise.

Can Increased Sodium Intake Reduce Exercise-associated Hyponatremia?

The primary risk factor for exercise-associated hyponatremia is overhydration, but other factors can play a role, including Na+ losses and intakes. PURPOSE: To test the efficacy of a CHO-containing (6%) beverage with 60 vs. 21 mmol/L on plasma [Na+] when consumed to nearly match mass loss, while cycling in the heat. METHODS: In a randomized, crossover study, 10 males (VO2max 60 ± 3 mL/min/kg, 75 ± 5 kg, 20-50 y) cycled (55% VO2max) in the heat (34 °C) for 3 h while consuming a beverage containing either 21 mmol/L Na+ (L) or 60 mmol/L Na+ (H). Beverage volume was based on body mass changes in 1 h pre-trials under similar conditions. Blood was sampled every 30 min. Tc, HR, and body mass were monitored. Linear mixed effects model analysis of variance was conducted with Subject as a random effect, and Diet and Time as fixed effects. T-tests were conducted on single measures. RESULTS: Not all subjects completed 3 h of exercise, with mean exercise time being 175 min on both L and H. Mean fluid intake was (3.3 ± 0.6 L, 3.4 ± 0.7 L, resp.; p=0.45). Body mass change was (-0.39 ± 0.31, -0.20 ± 0.36 kg, resp.; p=0.09). Plasma sodium decreased over time on L, whereas increased slightly on H (p< 0.001), with mean rate of change being (-0.6 ± 0.6 mmol/L/h, 0.6 ± 0.6 mmol/L/h, resp.; p =0.057). At ride completion, four subjects were hyponatremic (plasma [Na+] < 135 mmol/L) on L, and only one on H. No differences in end Tc (38.6 ± 0.8, 38.6 ± 0.8 °C, resp.; p=0.90) or end HR (147 ± 31, 157 ± 24 bpm, resp.; p=0.39) were observed. CONCLUSION: Consumption of a beverage with sodium concentration of 60 mmol/L has advantage over one with a concentration typically found in sports drinks (21 mmol/L), preventing plasma sodium reduction during long-lasting exercise in the heat.

Does exercise training impact clock genes in patients with coronary artery disease and type 2 diabetes mellitus?

Recent findings revealed negative effects of deregulated molecular circadian rhythm in coronary artery disease (CAD) and type 2 diabetes mellitus (T2DM). Physical exercise training (ET) has been shown to promote anti-diabetic and anti-atherogenic responses in skeletal muscle of these patients, but the role of the circadian clock-machinery remains unknown. This study investigated whether mRNA expression of clock genes in skeletal muscle of CAD and T2DM patients is influenced by physical ET intervention. Nineteen patients with CAD and T2DM (age 64 ± 5 years) were randomised to either six months of ET (four weeks of in-hospital ET followed by a five-month ambulatory programme) or usual care. At the beginning of the study, after four weeks and after six months parameters of metabolic and cardiovascular risk factors, and physical exercise capacity were assessed. Gene expression was measured in skeletal muscle biopsies by quantitative real-time polymerase chain reaction (PCR). A selection of clock genes and associated components (circadian locomoter output cycle kaput protein (CLOCK), period (PER) 1, cryptochrome (CRY) 2 and aminolevulinate-deltA-synthase-1 (ALAS1)) was reliably measured and used for further analysis. A time-dependent effect in gene expression was observed in CLOCK (p = 0.013) and a significant interaction between time and intervention was observed for ALAS1 (p = 0.032; p = 0.014) as a result of ET. This is the first study to analyse clock gene expression in skeletal muscles of patients with CAD and T2DM participating in a long-lasting exercise intervention. ET, as one of the cornerstones in prevention and rehabilitation of CAD and T2DM, exerts no effects on CLOCK genes but meaningful effects on the clock-associated gene ALAS1.

Changes in plasma leptin concentration during different types of exercises performed by horses

Leptin is a tissue-derivative adipokine that regulates appetite, food intake and energy expenditure. It is still not clear how exercise affects plasma leptin concentration in horses. The aim of this study was to evaluate the influence of exercise intensity and duration on plasma leptin levels in working horses. A total of 38 horses were prospectively included in the study and grouped according to the type of exercise they performed: dressage (six stallions, group D), jumping (12 stallions, group J), race (12 Thoroughbred horses, six stallions and six mares, group R) and harness (10 light draft stallions, group H). Blood samples were taken both before and after routine exercise (immediately after the exercise, 30 min and 24 h after). Blood lactic acid (LA) and plasma concentration of leptin, cortisol, uric acid, triacylglycerols, glycerol and free fatty acids were determined. Immediately after exercise, group R had the highest level of LA, whereas groups D and J had the lowest levels. A significant increase in plasma leptin concentration was stated only in group H in samples taken immediately after the end of the exercise period and 30 min after the exercise period, as compared with the values obtained at rest. A significant increase in plasma cortisol concentration was found immediately after the end of the exercise period in groups R and H. Leptin exercise-to-rest ratio was significantly correlated with cortisol exercise-to-rest ratio (r=0.64; P<0.001). The increase in plasma leptin concentration in exercised horses was related to the increased plasma cortisol concentration and took place only during long-lasting exercise, which was not intensive.

Exertional Compartment Syndrome Leading to Bilateral Foot Drop: A Case Report

BackgroundAlthough more commonly encountered with trauma, long-lasting exercise can cause a compartment syndrome. This is the first reported case of bilateral exertional compartment syndrome [ECS] that led to bilateral foot drop.FindingsA 20-year-old man presented with complaints of swelling and pain in both legs which starting after a long, strenuous exercise. Magnetic resonance imaging showed edema in the peroneus longus and brevis muscles. The electromyography examination demonstrated severe axonal degenerations on bilateral peroneus profundus nerves. The diagnosis of ECS of the both legs leading to bilateral foot drop was established. Decompressive fasciotomies was performed one month after the onset of complaints. Improvement after physical therapy and rehabilitation was not satisfactory.ConclusionsECS can be overlooked as a diagnosis. Surgical decompression is the best choice of treatment. Late diagnosis and delayed surgery might lead to poor prognosis.

Contribution of Nonesterified Fatty Acids to Mitogen-Activated Protein Kinase Activation in Human Skeletal Muscle During Endurance Exercise

Mitogen-activated protein kinase (MAPK) pathways are activated in skeletal muscle during endurance exercise, but the upstream molecular events are incompletely resolved. As an increase in plasma nonesterified fatty acids (NEFA) is a common feature of long-lasting exercise, the authors tested the hypothesis that NEFA contribute to the activation of MAPK during endurance exercise. Acipimox was used before and during endurance exercise to prevent the elevation of plasma NEFA levels in healthy subjects and patients with diabetes. In 2 separate studies, healthy subjects cycled for 2 hr and patients with diabetes for 1 hr at 50% Wmax. In control conditions, plasma NEFA concentrations increased from 0.35 to 0.90 mM during exercise in healthy subjects and from 0.55 to 0.70 mM in patients with diabetes (p < .05). Phosphorylation states of extracellularly regulated kinase 1 and 2 (ERK1/2), p38, and c-Jun NH2-terminal kinases (JNK) were significantly increased after exercise in the vastus lateralis in both groups. Acipimox blocked the increase in plasma NEFA concentrations and almost completely repressed any rise in ERK1/2 and p38 but not in JNK. In conclusion, the data support a role for plasma NEFA in the activation of p38 and ERK1/2 in skeletal-muscle tissue of healthy and diabetic subjects during endurance exercise. Further investigation will be required to determine the molecular link between NEFA and MAPK activation during exercise in human skeletal muscle.

Changes in EEG during Ultralong Running

There are only a few studies using human electroencephalograms (EEGs) to investigate bioelectrical changes in the brain during exercise (running or cycling). These studies report an increase in EEG alpha amplitude during and immediately after exercise. However, only exercises within a relatively short time interval of approximately 1 hour have been investigated. Thus, we focussed on long-lasting exercise and report three single case studies, performed on the same participant, during extended exercise and under different thermal conditions. EEG was recorded during a 12-, 24-, and 56-hour ultramarathon. The 56-hour race was performed under extreme thermal stress in Death Valley, CA, with temperatures well above 55uC/131uF. Analyzing the centre gravity frequency of the EEG alpha rhythm yielded a gradual decrease with time for the 12- and 24-hour races. In the 56-hour race, the centre frequency decreased only until the first sleeping period. Alpha amplitude, on the other hand, did not vary systematically. For all three races, the lowest alpha amplitude was observed during the last test session. This decrease is most likely due to cognitive and emotional changes but not to thermal stress, exhaustion, or sleep deprivation.

Achilles tendon stiffness is unchanged one hour after a marathon

Overuse-induced injuries have been proposed as a predisposing factor for Achilles tendon (AT) ruptures. If tendons can be overloaded, their mechanical properties should change during exercise. Because there data are lacking on the effects of a single bout of long-lasting exercise on AT mechanical properties, the present study measured AT stiffness before and after a marathon. AT stiffness was determined as the slope of the force-elongation curve between 10 and 80% of maximum voluntary force. AT force-elongation characteristics were measured in an ankle dynamometer using simultaneous motion-capture-assisted ultrasonography. Oxygen consumption and ankle kinematics were also measured on a treadmill at the marathon pace. All measurements were performed before and after the marathon. AT stiffness did not change significantly from the pre-race value of 197±62 N mm(-1) (mean ± s.d.) to the post-race value of 206±59 N mm(-1) (N=12, P=0.312). Oxygen consumption increased after the race by 7±10% (P<0.05) and ankle kinematic data revealed that in nine out of 12 subjects, the marathon induced a change in their foot strike technique. The AT of the physically active individuals seems to be able to resist mechanical changes under physiological stress. We therefore suggest that natural loading, like in running, may not overstress the AT or predispose it to injury. In addition, decreased running economy, as well as altered foot strike technique, was probably attributable to muscle fatigue.

Muscle Protein Turnover in Endurance Training: a Review

There has been much debate about skeletal muscle capacity to adapt to long-lasting endurance exercise. Exercise in the aerobic zone of metabolism does not result in hypertrophy of skeletal muscle fibres but increases their oxidative capacity. The duration and intensity of an exercise session determines the time period of depressed muscle protein synthesis and increased degradation rate during the recovery period after exercise. Protein turnover characterizes the renewal processes of muscle proteins and the functional capacity of muscle. The turnover rate of myofibrillar proteins is slow in comparison with mitochondrial proteins and depends on the oxidative capacity of muscle fibres. The turnover rate of myofibrillar proteins in the same muscle is different and is also different within the myosin molecule between myosin heavy and light chain isoforms. The turnover rate of muscle proteins in endurance training shows the adaptation of skeletal muscle to long-lasting exercise via remodelling of muscle structures. Adaptational coordination between myofibrillar and mitochondrial compartments shows the physiological role and adaptational capacity of skeletal muscle to endurance training. It is challenging to use muscle protein turnover for the purposes of monitoring the training process of endurance athletes, optimizing training programs and preventing overtraining.

Exercise rehabilitation on home-dwelling patients with Alzheimer disease: A randomized, controlled trial. Baseline findings and feasibility

Background There are scarce studies exploring effectiveness and feasibility of intensive and long-lasting exercise among patients with dementia. Purpose To present baseline findings of a randomized controlled trial exploring effectiveness of intensive physical exercise among home-dwelling patients with Alzheimer disease (AD), and to evaluate feasibility of the intervention by exploring feedback from spousal caregivers. Subjects and methods We used central AD registers in Finland to recruit AD patients ( n = 210) living with their spousal caregiver in the community. They were randomized into three arms: 1): tailored home-based exercise twice weekly ( n = 70); 2): group-based exercise in rehabilitation centers twice weekly in ( n = 70), and; 3): a control group with usual care and information of exercise and nutrition ( n = 70). Anonymous feedback from spousal caregivers was collected at 6 months of the intervention. Results The mean age of AD patients was 78.1 years (SD 5.3), 81 (39%) were women, and 104 (50%) were at moderate stage of dementia according to the Clinical Dementia Rating Scale (CDR). Of the caregivers, 94% had made the decision to participate in the trial because of their spouse's need for rehabilitation, and 93% felt that the study nurses’ assessments had been beneficial for them. Only 16 participants (8%) had dropped out before the first (3-month) follow-up assessment. Conclusion We have successfully randomized 210 patients with Alzheimer's disease and their spousal caregivers into an intensive exercise rehabilitation trial. The feedback from spousal caregivers was favourable and drop-out rate low at 6 months.

Short-term Glucocorticoid Intake and Metabolic Responses During Long-lasting Exercise

The aim of the study was to evaluate the effects of short-term glucocorticoid treatment on plasma amino acids, free fatty acids, blood glucose, and several hormones in healthy volunteers performing long-lasting exercise. 9 young female subjects exercised 2 h at 50-55% VO₂ max twice, once after placebo (Pla) ingestion and once after prednisone (Cor, 50 mg/day/7 days) ingestion, according to a double-blind and randomized protocol. Blood samples were tat rest and during exercise for measurement of amino acids, free fatty acids, blood glucose, adrenocorticotrophic hormone (ACTH), growth hormone, dehydroepiandrosterone (DHEA), insulin, and glucagon. Both ACTH and DHEA values were significantly decreased by Cor vs. Pla (p < 0.01) throughout exercise, and Cor intake also induced lower growth hormone concentrations vs. Pla (p < 0.05) from 60 min to the end of exercise. No significant difference in glucagon, insulin or free fatty acid values was found between the treatments. Branched-chain amino acids and other essential amino acids were significantly higher after Cor vs. Pla from 60 min to the end of exercise (p < 0.05), whereas blood glucose was significantly higher from 90 min to the end of exercise (p < 0.05). We conclude that short-term glucocorticoid intake induces marked hormonal and metabolic changes during long-lasting exercise. Proteolysis can increase with glucocorticoid during this type of exercise and the related higher plasma amino acid concentrations may contribute as energy substrates. Further studies will be necessary to explore and accurately quantify the mechanisms of proteolysis and glyconeogenesis induced by short-term glucocorticoid intake during this type of exercise.

Exercise rehabilitation on home-dwelling patients with Alzheimer's disease - a randomized, controlled trial. Study protocol

BackgroundBesides cognitive decline, Alzheimer's disease (AD) leads to physical disability, need for help and permanent institutional care. The trials investigating effects of exercise rehabilitation on physical functioning of home-dwelling older dementia patients are still scarce. The aim of this study is to investigate the effectiveness of intensive exercise rehabilitation lasting for one year on mobility and physical functioning of home-dwelling patients with AD.MethodsDuring years 2008-2010, patients with AD (n = 210) living with their spousal caregiver in community are recruited using central AD registers in Finland, and they are offered exercise rehabilitation lasting for one year. The patients are randomized into three arms: 1) tailored home-based exercise twice weekly 2) group-based exercise twice weekly in rehabilitation center 3) control group with usual care and information of exercise and nutrition. Main outcome measures will be Guralnik's mobility and balance tests and FIM-test to assess physical functioning. Secondary measures will be cognition, neuropsychiatric symptoms according to the Neuropsychiatric Inventory, caregivers' burden, depression and health-related quality of life (RAND-36). Data concerning admissions to institutional care and the use and costs of health and social services will be collected during a two year follow-up.DiscussionTo our knowledge this is the first large scale trial exploring whether home-dwelling patients with AD will benefit from intense and long-lasting exercise rehabilitation in respect to their mobility and physical functioning. It will also provide data on cost-effectiveness of the intervention.Trial registrationACTRN12608000037303

Dehydration and rehydration in competative sport

Dehydration, if sufficiently severe, impairs both physical and mental performance, and performance decrements are greater in hot environments and in long-lasting exercise. Athletes should begin exercise well hydrated and should drink during exercise to limit water and salt deficits. Many athletes are dehydrated to some degree when they begin exercise. During exercise, most drink less than their sweat losses, some drink too much and a few develop hyponatraemia. Athletes should learn to assess their hydration needs and develop a personalized hydration strategy that takes account of exercise, environment and individual needs. Pre-exercise hydration status can be assessed from urine frequency and volume, with additional information from urine color, specific gravity or osmolality. Changes in hydration status during exercise can be estimated from the change in body mass: sweat rate can be estimated if fluid intake and urinary losses are also measured. Sweat salt losses can be determined by collection and analysis of sweat samples. An appropriate, individualized drinking strategy will take account of pre-exercise hydration status and of fluid, electrolyte and substrate needs before, during and after a period of exercise.