Markers of biological stress in response to a single session of high-intensity interval training and high-volume training in young athletes.

PURPOSE: The aim of the present study was to compare the effects of high-intensity interval training (HIIT) vs high-volume training (HVT) on salivary stress markers [cortisol (sC), testosterone (sT), alpha-amylase (sAA)], metabolic and cardiorespiratory response in young athletes. METHODS: Twelve young male cyclists (14 ± 1 years; 57.9 ± 9.4 mL min-1 kg-1 peak oxygen uptake) performed one session of HIIT (4 × 4 min intervals at 90-95 % peak power output separated by 3 min of active rest) and one session of HVT (90 min constant load at 60 % peak power output). The levels of sC, sT, their ratio (sT/sC) and sAA were determined before and 0, 30, 60, 180 min after each intervention. Metabolic and cardiorespiratory stress was characterized by blood lactate, blood pH, respiratory exchange ratio (RER) and heart rate (HR), oxygen uptake ([Formula: see text]), ventilation (V E) and ventilatory equivalent (V E/[Formula: see text]). RESULTS: sC increased 30 and 60 min after HIIT. However, 180 min post exercise, sC decreased below baseline levels in both conditions. sT increased 0 and 30 min after HIIT and 0 min after HVT. sAA and sT/sC ratio did not change significantly over time in HIIT nor HVT. Metabolic and cardiorespiratory stress, evidenced by blood lactate, HR, [Formula: see text], V E, and V E/[Formula: see text] was higher during HIIT compared to HVT. CONCLUSION: The metabolic and cardiorespiratory stress during HIIT was higher compared to HVT, but based on salivary analyses (cortisol, testosterone, alpha-amylase), we conclude no strong acute catabolic effects neither by HIIT nor by HVT.

Polyamines, myosin heavy chains, and collagen specific amino acids after a repeated bout of eccentric exercise.

We investigated alternatives to commonly used biomarkers of exercise-induced tissue damage. Over 5 days following two bouts of 100 drop-to-vertical jumps (inter-bout rest period of 3 weeks), myosin heavy chain 1, hydroxylysine (HYL), hydroxyproline (HYP), spermine (SPM) and spermine synthase (SMS) were measured in the serum of 10 participants. HYL significantly increased from 5.92 ± 1.49 ng/mL to 6.48 ± 1.47 ng/mL at 24 h. A similar trend was observed for bout 2, but without reaching significance. SPM significantly increased only after bout 1 from 0.96 ± 0.19 ng/mL at pretest to a peak level of 1.12 ± 0.26 ng/mL at 24 h, while B2 increments remained non-significant. Myosin heavy chain 1, HYP and SMS values remained below the detection limit of the applied enzyme-linked immunosorbent assay (ELISA) kit. Though HYL and SM increased after the intervention, both markers showed a large standard deviation (SD) combined with small increments. Therefore, none of the investigated biomarkers provides a meaningful alternative to commonly used damage markers.

Acute Response of Circulating Vascular Regulating MicroRNAs during and after High-Intensity and High-Volume Cycling in Children.

AIM: The aim of the present study was to analyze the response of vascular circulating microRNAs (miRNAs; miR-16, miR-21, miR-126) and the VEGF mRNA following an acute bout of HIIT and HVT in children. METHODS: Twelve healthy competitive young male cyclists (14.4 ± 0.8 years; 57.9 ± 9.4 ml·min(-1)·kg(-1) peak oxygen uptake) performed one session of high intensity 4 × 4 min intervals (HIIT) at 90-95% peak power output (PPO), each interval separated by 3 min of active recovery, and one high volume session (HVT) consisting of a constant load exercise for 90 min at 60% PPO. Capillary blood from the earlobe was collected under resting conditions, during exercise (d1 = 20 min, d2 = 30 min, d3 = 60 min), and 0, 30, 60, 180 min after the exercise to determine miR-16, -21, -126, and VEGF mRNA. RESULTS: HVT significantly increased miR-16 and miR-126 during and after the exercise compared to pre-values, whereas HIIT showed no significant influence on the miRNAs compared to pre-values. VEGF mRNA significantly increased during and after HIIT (d1, 30', 60', 180') and HVT (d3, 0', 60'). CONCLUSION: RESULTS of the present investigation suggest a volume dependent exercise regulation of vascular regulating miRNAs (miR-16, miR-21, miR-126) in children. In line with previous data, our data show that acute exercise can alter circulating miRNAs profiles that might be used as novel biomarkers to monitor acute and chronic changes due to exercise in various tissues.

Acute Effects of Different Exercise Protocols on the Circulating Vascular microRNAs -16, -21, and -126 in Trained Subjects.

Aim: mircoRNAs (miRNAs), small non-coding RNAs regulating gene expression, are stably secreted into the blood and circulating miRNAs (c-miRNAs) may play an important role in cell-cell communication. Furthermore, c-miRNAs might serve as novel biomarkers of the current vascular cell status. Here, we examined how the levels of three vascular c-miRNAs (c-miR-16, c-miR-21, c-miR-126) are acutely affected by different exercise intensities and volumes. Methods: 12 subjects performed 3 different endurance exercise protocols: 1. High-Volume Training (HVT; 130 min at 55% peak power output (PPO); 2. High-Intensity Training (HIT; 4 × 4 min at 95% PPO); 3. Sprint-Interval Training (SIT; 4 × 30 s all-out). c-miRNAs were quantified using quantitative real-time PCR with TaqMan probes at time points pre, 0', 30', 60', and 180' after each intervention. The expression of miR-126 and miR-21 was analyzed in vitro, in human coronary artery endothelial cells, human THP-1 monocytes, human platelets, human endothelial microparticles (EMPs) and human vascular smooth muscle cells (VSMCs). To investigate the transfer of miRNAs via EMPs, VSMCs were incubated with EMPs. Results: HVT and SIT revealed large increases on c-miR-21 [1.9-fold by HVT (cohen's d = 0.85); 1.5-fold by SIT (cohen's d = 0.85)] and c-miR-126 [2.2-fold by SIT (cohen's d = 1.06); 1.9-fold by HVT (cohen's d = 0.85)] post-exercise compared to pre-values, while HIT revealed only small to moderate changes on c-miRs-21 (cohen's d = -0.28) and c-miR-126 (cohen's d = 0.53). c-miR-16 was only slightly affected by SIT (1.4-fold; cohen's d = 0.57), HVT (1.3-fold; cohen's d = 0.61) or HIT (1.1-fold; cohen's d = 0.2). Further in vitro experiments revealed that miR-126 and miR-21 are mainly of endothelial origin. Importantly, under conditions of endothelial apoptosis, miR-126 and miR-21 are packed from endothelial cells into endothelial microparticles, which were shown to transfer miR-126 into target vascular smooth muscle cells. Conclusion: Taken together, we found that HVT and SIT are associated with the release of endothelial miRNAs into the circulation, which can function as intercellular communication devices regulating vascular biology.

Serum Cartilage Oligomeric Matrix Protein: is There a Repeated Bout Effect?

The primary aim of the present study was to investigate if there is a repeated bout effect for cartilage tissue, evident in the marker serum cartilage oligomeric matrix protein (sCOMP). Ten healthy male subjects (26.4±3.14 years) performed two high impact interventions (100 drop jumps with a 30 second interval) carried out at a 3 week interval. After each intervention, sCOMP and muscle soreness were assessed on 8 and 6 occasions respectively. Muscle soreness was determined via a visual analog scale with a maximum pain score of 10. sComp levels did not show a blunted response after the second bout (Bout 1: 12.2±3.3 U/L(-1); Bout 2: 13.1±4.0 U/L(-1); P>0.05). Remarkably, sCOMP increased from baseline levels by 16% after bout 1 and 15% after bout 2. Muscle soreness was blunted following the second intervention (Bout 1: 5.0±1.8; Bout 2: 1.6±0.8). Unlike the known repeated bout effect for muscle damage markers, sCOMP levels do not show a blunted response after two similar loading interventions. This information on biomarker behavior is essential to clinicians attempting to use this marker as an indicator of cartilage damage associated with the development or progression of osteoarthritis.

Is leg compression beneficial for alpine skiers?

BACKGROUND: This study examined the effects of different levels of compression (0, 20 and 40 mmHg) produced by leg garments on selected psycho-physiological measures of performance while exposed to passive vibration (60 Hz, amplitude 4-6 mm) and performing 3-min of alpine skiing tuck position. METHODS: Prior to, during and following the experiment the electromygraphic (EMG) activity of different muscles, cardio-respiratory data, changes in total hemoglobin, tissue oxygenation and oscillatory movement of m. vastus lateralis, blood lactate and perceptual data of 12 highly trained alpine skiers were recorded. Maximal isometric knee extension and flexion strength, balance, and jumping performance were assessed before and after the experiment. RESULTS: The knee angle (-10°) and oscillatory movement (-20-25.5%) were lower with compression (P < 0.05 in all cases). The EMG activities of the tibialis anterior (20.2-28.9%), gastrocnemius medialis (4.9-15.1%), rectus femoris (9.6-23.5%), and vastus medialis (13.1-13.7%) muscles were all elevated by compression (P < 0.05 in all cases). Total hemoglobin was maintained during the 3-min period of simulated skiing with 20 or 40 mmHg compression, but the tissue saturation index was lower (P < 0.05) than with no compression. No differences in respiratory parameters, heart rate or blood lactate concentration were observed with or maximal isometric knee extension and flexion strength, balance, and jumping performance following simulated skiing for 3 min in the downhill tuck position were the same as in the absence of compression. CONCLUSIONS: These findings demonstrate that with leg compression, alpine skiers could maintain a deeper tuck position with less perceived exertion and greater deoxygenation of the vastus lateralis muscle, with no differences in whole-body oxygen consumption or blood lactate concentration. These changes occurred without compromising maximal leg strength, jumping performance or balance. Accordingly, our results indicate that the use of lower leg compression in the range of 20-40 mmHg may improve alpine skiing performance by allowing a deeper tuck position and lowering perceived exertion.