Impact of long-lasting moderate-intensity stage cycling event on cardiac function in young female athletes: A case study.

PURPOSE: Effects of intense and/or prolonged exercise have been studied extensively in male athletes. Nevertheless, data are scare on the effect of long duration events on cardiac function in female athletes. Our aim was to investigate the effect of a long-lasting moderate-intensity stage cycling event on cardiac function of young female athletes. METHODS: Seven well-trained female cyclists were included. They completed a cycling event of 3529 km on 23 days. All underwent an echocardiography on 6 time-points (baseline and at the arrival of day (D) 3, 7, 12, 13 and 23). Cardiac function was assessed by conventional echocardiography, tissue Doppler imaging and speckle tracking techniques. Daily exercise load was determined by heart rate (HR), power output and rate of perceived exertion data (RPE, Borg scale). RESULTS: All stages were mainly done at moderate intensity (average HR: 65% of maximal, average aerobic power output: 36% of maximal, average RPE: 4). Resting HR measured at the time of echocardiography did not vary during the event. Resting cardiac dimensions did not significantly change during the 23 days of cycling. No significant modification of cardiac function, whatever the studied cavity, were observed all along the event. CONCLUSION: The results suggest that, in the context of our case study, the long-lasting moderate-intensity stage cycling event was not associated with cardiac function alteration. Nevertheless, we must be careful in interpreting them due to the limits of an underpowered study.

Cardiac Events in World-Class Athletes: An Internet-Based Study.

PURPOSE: This study aimed at assessing the prevalence of adverse cardiac events, as identified in the media, in world-class athletes according to their sex and sports discipline. METHODS: All female and male athletes from 30 individual Olympic sports who ranked in the international yearly top 10 between 2006 and 2018 were included. The name of each of them was associated in a Google search with selected key terms related to heart disease and/or acute cardiac events after their inclusion date. Global and sex-specific adverse cardiac event hazard function λ were calculated for each sport. Global and sex-specific prevalences of cardiac events were calculated, then compared (Fisher's exact test) between all sports. RESULTS: From the 2471 athletes included, 15 cases of cardiac events (prevalence of 0.61%) were reported; 2 sudden cardiac deaths (0.08%) occurred in male athletes. The other events were related to arrhythmic events ( n = 13), mainly supraventricular arrhythmias ( n = 9). All surviving athletes were able to continue their career, mostly after ablation procedure. Male endurance athletes accounted for seven events, among which three events occurred among short-distance triathletes. Events among women were comparatively rare ( n = 4), and all were observed among short-distance triathletes. CONCLUSIONS: A relatively unexpected high prevalence of cardiac events in endurance elite athletes was observed as compared with other sports, mainly, in short-distance male and female triathletes. This raises the question of particular cardiovascular constraints in this discipline and underlines the urge of international longitudinal follow-up studies in these kinds of athletes.

Exercise-Induced Cardiac Fatigue in Soldiers Assessed by Echocardiography.

Background: Echocardiographic signs of exercise-induced cardiac fatigue (EICF) have been described after strenuous endurance exercise. Nevertheless, few data are available on the effects of repeated strenuous exercise, especially when associated with other constraints as sleep deprivation or mental stress which occur during military selection boot camps. Furthermore, we aimed to study the influence of experience and training level on potential EICF signs. Methods: Two groups of trained soldiers were included, elite soldiers from the French Navy Special Forces (elite; n = 20) and non-elite officer cadets from a French military academy (non-elite; n = 38). All underwent echocardiography before and immediately after exposure to several days of uninterrupted intense exercise during their selection boot camps. Changes in myocardial morphology and function of the 4 cardiac chambers were assessed. Results: Exercise-induced decrease in right and left atrial and ventricular functions were demonstrated with 2D-strain parameters in both groups. Indeed, both atrial reservoir strain, RV and LV longitudinal strain and LV global constructive work were altered. Increase in LV mechanical dispersion assessed by 2D-strain and alteration of conventional parameters of diastolic function (increase in E/e' and decrease in e') were solely observed in the non-elite group. Conventional parameters of LV and RV systolic function (LVEF, RVFAC, TAPSE, s mitral, and tricuspid waves) were not modified. Conclusions: Alterations of myocardial functions are observed in soldiers after uninterrupted prolonged intense exercise performed during selection boot camps. These alterations occur both in elite and non-elite soldiers. 2D-strain is more sensitive to detect EICF than conventional echocardiographic parameters.

Modeling Stress-Recovery Status Through Heart Rate Changes Along a Cycling Grand Tour.

BACKGROUND: Heart rate (HR) and HR variability (HRV) indices are established tools to detect abnormal recovery status in athletes. A low HR and vagally mediated HRV index change between supine and standing positions reflected a maladaptive training stress-recovery status. OBJECTIVES: Our study was focused on a female multistage cycling event. Its overall aim was twofold: (1) quantify the correlation between (a) the change in HR and HRV indices during an active orthostatic test and (b) subjective/objective fatigue, physical load, and training level indicators; and (2) formulate a model predicting the stress-recovery status as indexed by Δ â¢ R ⁢ R ¯ and ΔLnRMSSD (defined as the difference between standing and supine mean RR intervals and LnRMSSD, respectively), based on subjective/objective fatigue indicators, physical load, and training levels. METHODS: Ten female cyclists traveled the route of the 2017 Tour de France, comprising 21 stages of 200 km on average. From 4 days before the beginning of the event itself, and until 1 day after its completion, every morning, each cyclist was subjected to HR and HRV measurements, first at rest in a supine position and then in a standing position. The correlation between HR and HRV indices and subjective/objective fatigue, physical load, and training level indicators was then computed. Finally, several multivariable linear models were tested to analyze the relationships between HR and HRV indices, fatigue, workload, and training level indicators. RESULTS: HR changes appeared as a reliable indicator of stress-recovery status. Fatigue, training level, and Δ â¢ R ⁢ R ¯ displayed a linear relationship. Among a large number of linear models tested, the best one to predict stress-recovery status was the following: Δ â¢ R ⁢ R ¯ = 1,249.37+12.32V̇O2 max + 0.36 km⋅week-1-8.83 HR max -5.8 RPE-28.41 perceived fatigue with an adjusted R 2 = 0.322. CONCLUSION: The proposed model can help to directly assess the adaptation status of an athlete from RR measurements and thus to anticipate a decrease in performance due to fatigue, particularly during a multistage endurance event.

Daily fatigue-recovery balance monitoring with heart rate variability in well-trained female cyclists on the Tour de France circuit.

OBJECTIVES: This study aimed to analyze the daily heart rate variability (HRV) in well-trained female cyclists during the 2017 Tour de France circuit and to relate it to the load and perceived exertion response. METHODS: Ten female cyclists volunteered to participate in the study. HRV was recorded with a portable heart rate monitor each morning at rest in supine (7 min.) and upright (7 min.) positions, as well as throughout each day's stage. Pre-Tour baseline HRV recordings were made, as well as during the four weeks following completion of the Tour. Exercise daily load was assessed using the training impulse score (TRIMPS). Post-exercise rate of perceived exertion (RPE) was assessed daily using the Borg CR-10 scale. RESULTS: The results show a HRV imbalance, increase of sympathetic and decrease of vagal activities respectively, along the event that correlated with rate of perceived exertion (r = 0.46), training impulse score (r = 0.60), and kilometers (r = 046). The greatest change in HRV balance was observed the days after the greatest relative physical load. Mean heart rate and heart rate variability values returned to their baseline values one week after completion of the event. CONCLUSIONS: Despite incomplete recovery from day-to-day, fatigue is not summative or augmented with each successive stage and its physical load. Just one week is sufficient to restore baseline values. Heart rate and HRV can be used as a tool to strategically plan the effort of female cyclists that participate in multi-stage events.

Physical activity and diabetic cardiomyopathy: myocardial adaptation depending on exercise load.

Diabetes mellitus (DM), an increasing health problem worldwide, is associated with severe cardiovascular complications. To date, the beneficial effects of physical activity in both prevention and treatment of DM and its complications are well established. Nevertheless, it appears that exercise training, depending on the load, exerts differential effects on the myocardium. Hence, in this review, the impact of exercise training, focusing on exercise modalities and adaptations in response to load, on diabetic cardiovascular function, are discussed. Molecular mechanisms that may be involved in these adaptions to exercise training are also addressed.

Intense exercise training is not effective to restore the endothelial NO-dependent relaxation in STZ-diabetic rat aorta.

BACKGROUND: The aim of this study was to examine the effects of intense physical training on vascular function in streptozotocin-diabetic rats. We focused on the endothelium-dependent relaxation (EDR) induced by acetylcholine (ACh) and stable ADP adenosine-5'- O - (2-thiodiphosphate) (ADPßS). METHODS: Control or diabetic male Wistar rats (n=44) were randomly assigned to sedentary or trained groups. The training program consisted in a regular period of running on a treadmill during 8 weeks (10° incline and up to 25 m/min, 60 min/day). The reactivity of isolated thoracic aorta rings of healthy, diabetic and/or trained has been tested. RESULTS: ACh and ADPßS-induced EDR were observed in phenylephrine (PE) pre-contracted vessels. As compared to sedentary control group, diabetic rats showed an increase in PE-induced contraction and a decrease in ACh and ADPßS-induced EDR (p<0.05). Moreover, there were no increase in ACh and ADPßS-induced EDR in diabetic rats. N-Nitro-L-Arginine Methyl Ester inhibited the nitric oxide synthase in diabetic and control rats, thereby resulting in a strong inhibition of the EDR induced by ACh and ADPßS (10-6 M). CONCLUSION: Diabetes induced an endothelium dysfunction. Nevertheless, our intense physical training was not effective to restore the aorta endothelial function.

Energy system contribution to Olympic distances in flat water kayaking (500 and 1,000 m) in highly trained subjects.

Olympic flat water kayaking races take place over a distance of 500 and 1,000 m. This study was designed to determine the aerobic and anaerobic contributions to 500- and 1,000-m races during flat water paddling in open water, using the accumulated oxygen deficit (AOD) method. Seven internationally ranked athletes, specialized in 500-m races and familiar with 1,000-m races, participated in this study (age: 21.86 ± 1.68 years, body mass: 78.54 ± 3.41 kg, height: 1.84 ± 0.03 m, body fat%: 10.14 ± 0.69%). All the participants performed 3 track-kayaking sessions. During the first session, the maximal oxygen uptake and maximal aerobic speed were determined using a portable gas analyzer and a global positioning system. During the successive testing sessions, paddlers performed in a randomized counterbalanced order a 500- and a 1,000-m race under field conditions (open water track kayaking). The 500-m AOD was significantly higher than the 1,000-m AOD (18.16 ± 4.88 vs. 9.34 ± 1.38 ml·kg(-1), p < 0.05). The aerobic contribution resulted in being higher during the 1,000 m compared with that in the 500-m condition (86.61 ± 1.86% vs. 78.30 ± 1.85%, respectively, p < 0.05). The results of this study showed that the 500- and 1,000-m races are 2 physiologically different kayaking events with a higher aerobic contribution in the 1,000 m. The training prescription for elite athletes should emphasize aerobic high-intensity training for the 1,000 m and anaerobic short-term training for the 500-m race.

Combined insulin treatment and intense exercise training improved basal cardiac function and Ca(2+)-cycling proteins expression in type 1 diabetic rats.

This study investigated the effects of 8 weeks of intense exercise training combined with insulin treatment on the Ca(2+)-cycling protein complex expression and their functional consequences on cardiac function in type 1 diabetic rat hearts. Diabetic Wistar rats were randomly assigned into the following groups: received no treatment, insulin-treated diabetic, trained diabetic, and trained insulin-treated diabetic. A control group was also included. Insulin treatment and (or) treadmill intense exercise training were conducted over 8 weeks. Basal cardiac function was evaluated by Langendorff technique. Cardiac expression of the main Ca(2+)-cycling proteins (RyR2, FKBP 12.6, SERCA2, PLB, NCX1) was assessed by Western blot. Diabetes altered basal cardiac function (±dP/dt) and decrease the expression of the main Ca(2+)-cycling proteins expression: RyR2, SERCA2, and NCX1 (p < 0.05). Whereas combined treatment was not able to normalize -dP/dt, it succeeded to normalize +dP/dt of diabetic rats (p < 0.05). Moreover, both insulin and intense exercise training, applied solely, increased the expression of the Ca(2+)-cycling proteins: RyR2, SERCA2, PLB. and NCX1 (p < 0.05). But this effect was higher when the 2 treatments were combined. These data are the first to show that combined insulin treatment and intense exercise training during diabetes synergistically act on the expression of the main Ca(2+)-cycling proteins, providing insights into mechanisms by which the dual treatment during diabetes improves cardiac function.

Effects of treadmill exercise and training frequency on anabolic signaling pathways in the skeletal muscle of aged rats.

Physical exercise is the most effective intervention against sarcopenia of aging; however, the cellular and molecular mechanisms mediating training-induced adaptations are not yet completely understood. Furthermore, it is unclear whether exercise training initiated late in life affects myocyte anabolic signaling in a dose-dependent manner. Hence, we sought to investigate the effects of treadmill exercise and training frequency on anabolic pathways, including insulin signaling, in the skeletal muscle of old rats. Aged (14-16-month-old) male Wistar rats were trained on a treadmill for 3 (EX3) or 5 days/week (EX5) during 8 weeks and compared with age-matched sedentary controls (SED). Four-month-old rats were used as young controls (YC). Protein expression levels of insulin receptor (IR), insulin receptor substrate 1 (IRS-1), activated (phosphorylated) mammalian target of rapamycin (p-mTOR) and glucose transporter GLUT4 were determined in quadriceps muscle extracts via immunoblotting. Mitochondrial cytochrome c oxidase (COX) activity was assessed by histochemical staining, while electron microscopy was employed to quantify the sarcomere volume (V(src)). Body weight (BW) increased, whereas muscle weight (MW) and V(src) decreased with age. EX5, but not EX3 increased MW and V(src), without affecting BW. The expression of IR and GLUT4 was higher in SED rats relative to the YC group. Conversely, protein levels of IRS-1 and p-mTOR as well as COX activity were reduced in advanced age. Compared with SED rats, EX3 animals displayed reduced IR expression and increased IRS-1 levels and COX activity. The expression of GLUT 4 and p-mTOR was unaffected by EX3. EX5 up-regulated IRS-1 and p-mTOR expression and COX activity, while decreasing GLUT4 levels, with no effect on IR expression. In summary, substantial impairments in muscle anabolic pathways, including insulin signaling, were detected in aged sedentary rats. These changes were ameliorated by exercise training, concomitant with improvements in muscle trophism. Benefits were more evident in rats trained for 5 days/week, suggesting that physical exercise initiated late in life affects anabolic signaling in a dose-dependent manner.

Effects of exercise training combined with insulin treatment on cardiac NOS1 signaling pathways in type 1 diabetic rats.

This study examined the effects of a dual treatment combining insulin treatment and exercise training on basal cardiac function and signaling pathways involving ß3-AR, NOS1, and RyR2 in type 1 diabetic rats. Male Wistar rats were assigned into a diabetic group receiving no treatment (D), an insulin-treated diabetic (Ins), a trained diabetic (TD), and a trained insulin-treated diabetic (TIns) group. Control group (C) was included in order to confirm the deleterious effects of diabetes. Insulin treatment and/or treadmill exercise training were conducted for 8 weeks. Basal cardiac function was evaluated by Langendorff technique. Cardiac protein expression of ß3-AR, NOS1, and RyR2 was assessed using Western blots. Diabetes induced a decrease of both basal diastolic and systolic (±dP/dt) cardiac function (P < 0.05). Moreover, diabetes was associated with an increase of ß3-AR and NOS1 and a decrease of RyR2 expression (P < 0.05). Although combined treatment was not able to normalize -dP/dt, it succeeded to normalize +dP/dt of diabetic rats. Combined treatment led to an overexpression of RyR2. Effects of this combined treatment on +dP/dt and RyR2 were greater than the effects of insulin and exercise training, applied solely. Treatments, applied solely or in combination, resulted in a complete normalization of ß3-AR and in a down-regulation of NOS1 because this protein expression in all treated diabetic rats became lower than control values (P < 0.01). Our study shows that unlike single treatments, dual treatment combining insulin treatment and exercise training was able to normalize basal systolic function of diabetic rats by a specific regulation of ß3-AR-NOS1-RyR2 signaling pathways.