The aim of this study was to investigate inter-day and -week as well as intra- and inter-individual variation of selected biomarkers in high-performance youth soccer players to assist practitioners ...interpreting player’s internal load to counteract underperformance and unwanted health risks. Eleven male youth soccer players were tested multiple times during two 3-week periods at midpoint (3-wk
mid
) and at the end (3-wk
end
) of the first half of a German under-19 1. Bundesliga season. The levels of creatine kinase (CK), urea, and C-reactive protein (CRP) were measured during 3-wk
mid
and 3-wk
end
each Monday, Wednesday, and Friday. In 3-wk
mid
the CK median was 14% higher (241 vs. 212 U/L) compared to 3-wk
end
(
P
= 0.26, ES = 0.16). Overall, the medians of CK, urea (
P
= 0.59, ES = 0.08), and CRP (
P
= 0.56, ES = 0.10) during 3-wk
mid
did not differ to the values of 3-wk
end
. Daily coefficient of variations (CVs) ranged from 22 to 71% (CK), 17 to 37% (urea), and 9 to 164% (CRP). Individual medians ranged from 101 to 350 U/L (CK), 23 to 50 mg/dL (urea), and 0.6 to 1.1 mg/L (CRP). High intra-individual variability was demonstrated by large intra-individual CVs (medians: CK 50%, urea 18%, and CRP 45%). Our data show (i) large inter-day and inter-week variability of all biomarkers, depending on the external load and (ii) considerable inter- and intra-individual parameter variations. Creatine kinase concentrations could sensitively reflect soccer-specific loads during the season.
Endothelial microparticles (EMP) are complex vesicular structures shed from activated or apoptotic endothelial cells. As endurance exercise affects the endothelium, the objective of the study was to ...examine levels of EMP and angiogenic growth factors following different endurance exercise protocols.
12 subjects performed 3 different endurance exercise protocols: 1. High volume training (HVT; 130 min at 55% peak power output (PPO); 2. 4 × 4 min at 95% PPO; 3. 4 × 30 sec all-out. EMPs were quantified using flow cytometry after staining platelet-poor-plasma. Events positive for Annexin-V and CD31, and negative for CD42b, were classified as EMPs. Vascular endothelial growth factor (VEGF), migratory inhibiting factor (MIF) and hepatocyte growth factor (HGF) were determined by ELISA technique. For all these measurements venous blood samples were taken pre, 0', 30', 60' and 180' after each intervention. Furthermore, in vitro experiments were performed to explore the effect of collected sera on target endothelial functions and MP uptake capacities.
VEGF and HGF significantly increased after HIT interventions. All three interventions caused a significant decrease in EMP levels post exercise compared to pre values. The sera taken after exercise increased the uptake of EMP in target endothelial cells compared to sera taken under resting conditions, which was shown to be phosphatidylserin-dependent. Increased EMP uptake was associated with an improved protection of target cells against apoptosis. Sera taken prior and after exercise promoted target endothelial cell migration, which was abrogated after inhibition of VEGF.
Physical exercise leads to decreased EMP levels and promotes a phosphatidylserin-dependent uptake of EMP into target endothelial cells, which is associated with a protection of target cells against apoptosis.
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 (
V
O
2
), ventilation (
V
E
) and ventilatory equivalent (
V
E
/
V
O
2
).
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,
V
O
2
,
V
E
, and
V
E
/
V
O
2
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.
▶ Blood lactate is involved in the regulation of BDNF blood concentrations. ▶ Strengthening the assumption that high intensity exercise increases BDNF in blood. ▶ The lactate clamp can be used to ...examine BDNF responses in healthy humans.
Studies in humans use blood lactate to determine the degree of the exercise intensity, suggesting that exercise with elevated blood lactate concentrations results in increased BDNF plasma concentrations. However, it is not clear if lactate per se or rather other mechanisms are responsible for changes in blood BDNF concentrations. The lactate clamp method at rest is an appropriate method to examine physiological responses of lactate on the human organism without the effects of exercise. Eight male sport students placed in a sitting position received intravenous infusions with a 4 molar sodium-lactate solution in an incremental design starting with an infusion rate of 0.01
ml/kgBW/min for the first three minutes, which was increased every three minutes by 0.01
ml/kgBW/min up to 0.08
ml/kg/min in the 24th minute. All together each subject received 4.2
mmol of infusion. Venous blood samples were taken before and immediately after the infusion as well as in the 24th and the 60th min after the infusion period and analysed for BDNF. Blood gases and capillary blood lactate (La) were analysed before the test, every three minutes directly before increasing the infusion rate, at the end of the infusion and in the post infusions period until the 12th min and after 24 and 60
min. BDNF and La increased significantly after the infusion and reached baseline values at the end of the experiment (
p
<
0.05,
p
<
0.01, respectively). pH and hydrogen ions increased from the beginning until the end of the infusion period (
p
<
0.01). This data suggest that blood lactate is involved in the regulation of BDNF blood concentrations.
Previous intervention studies suggest that leptin, insulin, insulin-like growth factor 1 (IGF-1), and triiodthyronine (T3) are sensitive markers of inadequate energy intake in relation to exercise ...expenditures. Because of limitations in metabolic hormone measurements, self-reported energy availability (EA) based on food and activity records may present an alternative for characterizing energy status in young athletes. The purpose of the current study was to assess whether self-reported EA is related to leptin, insulin, IGF-1, and T3 in 352 young athletes. Sex, body composition, sport participation, and acute weight changes were considered as confounding variables. Multiple linear regression revealed that EA was negatively associated with leptin (p < 0.05) but not with insulin, IGF-1, or T3. Female athletes with low EA (<30 kcal·kg
−1
fat-free mass (FFM)) had higher leptin concentrations (5.0 ± 4.7 ng·mL
−1
) and more body fat (18.3% ± 5.1%) than did females with normal EA (leptin, 3.1 ± 2.4 ng·mL
−1
; body fat, 15.8% ± 4.2%; both, p < 0.001). Athletes reporting acute weight loss (>1 kg·week
−1
) had a lower EA (18.9 ± 7.4 kcal·kg
−1
FFM) than did weight-stable athletes (30.0 ± 11.2 kcal·kg
−1
FFM) or athletes reporting weight gain (>1 kg; 49.7 ± 13.1 kcal·kg
−1
FFM). IGF-1 and T3 were also reduced in athletes who lost weight (p < 0.01). This cross-sectional study reveals a lack of association between self-reported EA and metabolic hormones indicative of energy status in young athletes. Further studies are needed to investigate whether self-reported EA and metabolic hormones are in better agreement when measured repeatedly.
Background and Objectives: During intense training periods, there is a high need to monitor the external and especially the internal training load in order to fine-tune the training process and to ...avoid overreaching or overtraining. However, data on stress reactions, especially of biomarkers, to high training loads in children and youth are rare. Therefore, in this study, we aimed to investigate the training load of youth athletes during a training camp using a multilevel approach. Materials and Methods: Six trained youth male cyclists performed a 7-day preseason training camp. To investigate the internal training load, every morning, minimally invasive “point-of-care testing” (POCT) devices were used to analyze the following biomarkers: creatine kinase (CK), blood urea nitrogen (BUN), albumin (Alb), bilirubin (Bil), alanine aminotransferase (ALT), aspartate aminotransferase (AST), and total protein (TP). Additionally, data of training load measures (HR: heart rate, RPE: rating of perceived exertion, sRPE: session-RPE, TRIMP: training impulse, intensity (RPE:HR), and load (sRPE:TRIMP) ratios), self-perception (person’s perceived physical state, questionnaires on muscle soreness, and sleep quality), and measures of the autonomic nervous system (resting heart rate, heart rate variability) were collected. Two days before and after the training camp, subjects performed performance tests (Graded Exercise Test, Wingate Anaerobic Test, Counter Movement Jump). Results: Primarily, the biomarkers CK, BUN, and Alb, as well as the self-perception showed moderate to large load-dependent reactions during the 7-day training camp. The biomarkers returned to baseline values two days after the last training session. Power output at lactate threshold showed a small increase, and no changes were found for other performance parameters. Conclusions: The study suggests that a multilevel approach is suitable to quantify the internal training load and that different parameters can be used to control the training process. The biomarkers CK, BUN, and Alb are suitable for objectively quantifying the internal training load. The self-perception provides additional subjective information about the internal training load.
Background and Objectives: Angiogenesis describes the outgrowth of new capillaries from already existing ones. Different biomarkers regulate this process. Physical exercise and hypoxia are key ...stimuli for the activation of different angiogenic molecules, such as the vascular endothelial growth factor (VEGF). matrix metalloproteases (MMPs)-2 and -9 or the extracellular matrix cleavage fragment endostatin. The present study aimed to investigate influences of short-term, intensive cycling exercise under both normoxic and normobaric hypoxic conditions on the mentioned parameters. Materials and Methods: Twelve male subjects (age: 23.3 ± 2.0 years) participated in the study. All subjects conducted four intensive cycling tests until individual exhaustion in a randomized order under the following conditions: normoxia, 2000 m, 3000 m and 4000 m above sea level. Blood samples were taken before (pre) and 10 min, 30 min, 60 min and 240 min post exercise and were analyzed by ELISA. Results: VEGF showed a significantly reduced concentration compared to the pre-value solely under 4000 m at 10 min post exercise. MMP-2 showed significantly reduced concentrations at 240 min post exercise under 4000 m. MMP-9 increased at 240 min post exercise under both 2000 m and 4000 m conditions. Endostatin was significantly increased at 10 min post exercise independently of the applied stimulus. Conclusions: The presented data show that intensive short-term exercise bouts facilitate the bioavailability of angiogenic, ECM (extracellular matrix)-related biomarkers. This finding is interesting for both health- and performance-related research as it demonstrates the positive effects of intensive short exercise interventions.
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.
This study aimed to investigate the biological response to hypoxia as a stimulus, as well as exercise- and vibration-induced shear stress, which is known to induce angiogenesis. Twelve male cyclists ...(27.8 +/- 5.4 yr) participated in this study. Each subject completed four cycle training sessions under normal conditions (NC) without vibration, NC with vibration, normobaric hypoxic conditions (HC) without vibration, and HC with vibration. Each session lasted 90 min, and sessions were held at weekly intervals in a randomized order. Five blood samples (pretraining and 0 h post-, 0.5 h post-, 1 h post-, and 4 h posttraining) were taken from each subject at each training session. Hypoxia was induced by a normobaric hypoxic chamber with an altitude of 2,500 m. The mechanical forces (cycling with or without vibration) were induced by a cycling ergometer. The parameters VEGF, endostatin, and matrix metalloproteinases (MMPs) were analyzed using the ELISA method. VEGF showed a significant increase immediately after the exercise only with exogenously induced vibrations, as calculated with separate ANOVA analysis. Endostatin increased after training under all conditions. Western blot analysis was performed for the determination of endostatin corresponding to the 22-kDa cleavage product of collagen XVIII. This demonstrated elevated protein content for endostatin at 0 h postexercise. MMP-2 increased in three of the four training conditions. The exception was NC with vibration. MMP-9 reached its maximum level at 4 h postexercise. In conclusion, the results support the contention that mechanical stimuli differentially influence factors involved in the induction of angiogenesis. These findings may contribute to a broader understanding of angiogenesis.
Current research in brain stimulation suggests transcutaneous auricular vagus nerve stimulation (taVNS) as a promising tool to modulate cognitive functions in healthy populations, such as attention, ...memory, and executive functions. Empirical evidence in single-task contexts, suggests that taVNS promotes holistic task processing, which strengthens the integration of multiple stimulus features in task processing. However, it is unclear how taVNS might affect performance in multitasking, where the integration of multiple stimuli leads to an overlap in stimulus response translation processes, increasing the risk of between-task interference (crosstalk). In a single-blinded, sham-controlled, within-subject design, participants underwent taVNS while performing a dual task. To assess the effects of taVNS, behavioral (reaction times), physiological (heart rate variability, salivary alpha-amylase), and subjective psychological variables (e.g., arousal) were recorded over three cognitive test blocks. Our results revealed no overall significant effect of taVNS on physiological and subjective psychological variables. However, the results showed a significant increase in between-task interference under taVNS in the first test block, but not in the subsequent test blocks. Our findings therefore suggest that taVNS increased integrative processing of both tasks early during active stimulation.
•taVNS enhances integrative dual-task processing.•taVNS increases between-task interference in dual tasking.•Effects of taVNS in multitasking are time-dependent.
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