High-intensity Exercise Research Articles

The effect of age on heart rate variability indices during and following high-intensity continuous exercise in masters and young cyclists.

This study compared heart rate variability (HRV) parameters of cardiovascular autonomic regulation between well-trained masters and young cyclists at rest, during and following a continuous cycle (CTS) protocol. Ten masters (age = 56 ± 5years) and eight young (age = 26 ± 3years) cyclists completed a 100min experimental protocol consisting of a 60min CTS cycling bout at 95% of Ventilatory Threshold 2 followed by 40min of supine recovery. Beat-to-beat heart rate was measured continuously, and HRV parameters analysed at standardised 5min intervals during rest, exercise and recovery. The root mean square of the successive differences (RMSSD), low-frequency power and high-frequency power parameters were corrected by division of the R-R interval (time domain), or R-R interval squared (frequency domain). Further, the RMSSD and RMSSD:RR for successive 60-s R-R intervals at the onset (0-10min) and offset (60-70min) of CTS exercise were analysed over 10-min periods. The natural logarithm (Ln) of skewed parameters was taken for analysis. Significant interaction effects (P < 0.05) for 5min segments were found for (LnRMSSD, LnRMSSD:RR, LnHF and LnHF:RR2. Masters cyclists demonstrated lower values of parasympathetic activity at rest and during recovery (15-20min and 35-40min) compared to younger cyclists. However, similar HRV responses were observed during exercise, including throughout the acute onset and offset periods (P > 0.05). This data shows that cardiac autonomic regulation during, or immediately following CTS exercise may not be influenced by age, but masters athletes may exhibit a lower baseline for parasympathetic activity.

Effectiveness of High-Intensity Circuit Training on Physical Fitness Among Athletes: A Systematic Review of Randomized-Controlled and Non-Controlled Trials

Background and Aim of the Study: The continuous evolution of sports and athletics necessitates innovative training strategies to optimize athletes’ performance and physical fitness. High-Intensity Circuit Training (HICT) has emerged as a time-efficient method that combines high-intensity exercises with minimal rest, targeting various muscle groups to enhance physical fitness components. Therefore, this systematic review aims to evaluate the effectiveness of HICT on physical fitness components among athletes to provide a clear, evidence-based understanding of HICT’s benefits and limitations. Material and Methods: A comprehensive search strategy was employed, retrieving articles published before September 24, 2023, from databases including the Cochrane Central Register of Controlled Trials, PubMed, and Google Scholar. The selection process followed the PRISMA guidelines, focusing on studies that assessed the impact of HICT on athletes’ physical fitness. The quality of included studies was assessed using the PEDro scale, and data synthesis was conducted to summarize findings on various physical fitness components. Results: The review included 13 studies, highlighting HICT’s positive effects on muscle strength, endurance, flexibility, balance, power, body composition, and cardiovascular endurance. Improvements were noted in neuromuscular efficiency, muscle power, coordination, and cardiovascular fitness, which are crucial for athletic performance. However, the review also identified variability in training adaptations and the need for sport-specific exercises to maximize the benefits of HICT for speed and power enhancements. Conclusions: HICT is a versatile and effective training modality that can significantly improve various aspects of athletes’ physical fitness. Incorporating targeted, sport-specific exercises into HICT programs could further optimize performance enhancements. Despite promising findings, the review acknowledges methodological heterogeneity among studies and calls for further research to refine HICT protocols for athletes.

High-intensity resistance training and collagen supplementation improve patellar tendon adaptations in professional female soccer athletes.

We investigated whether 10 weeks of pre-season soccer training (including high-intensity resistance exercise) with hydrolysed collagen (COL) supplementation would confer greater changes in patellar tendon (PT) mechanical and material properties compared with placebo (PLA) in professional female soccer athletes. Eleven athletes from the first team squad of a Football Association Women's Championship soccer club volunteered to participate in this study (age, 25.7±4.2 years; height, 1.68±0.04m; mass, 64.0±4.6kg). Participants were pair-matched for baseline knee extensor maximum isometric voluntary contraction torque, age, height and mass and were randomly assigned to the COL group (n=6) or PLA group (n=5). Participants were given 30g COL or energy-matched (36.5g maltodextrin and 8.4g fructose) PLA, plus 500mg vitamin C before each training session, which consisted of high-intensity lower-limb resistance exercise, plyometric or pitch-based exercise 3 days/week for 10weeks during the pre-season period. We assessed knee extensor maximum isometric voluntary contraction torque and PT properties using isokinetic dynamometry and ultrasonography before and after the intervention. The PT stiffness [COL, +15.4%±3.1% (d=0.81) vs. PLA, +4.6%±3.0% (d=0.32), P=0.002] and Young's modulus [COL, +14.2%±4.0% (d=0.65) vs. PLA, +3.4%±2.8% (d=0.15), P=0.004] increased more in COL than in PLA. There was a main effect of training on PT cross-sectional area (P=0.027), but no interaction effect (P=0.934). To conclude, 10 weeks of pre-season soccer training (incorporating high-intensity resistance exercise) with 30g COL increased PT stiffness and Young's modulus more than training alone in professional female soccer athletes. This has positive implications for improving athletic performance and mitigating injury risk.

Prevalence of electrocardiographic markers associated with myocardial fibrosis in masters athletes: a cohort study

ObjectivesMyocardial fibrosis (MF) is associated with an increased predisposition to adverse cardiac events. The accumulation of high-volume and high-intensity exercise over an extended duration potentially increases the risk of MF....

A mendelian randomisation study of the causal effect of exercise intensity on the development of type 2 diabetes.

This study examines the causal effects of varying exercise intensities on type 2 diabetes mellitus (T2D) through Mendelian randomization (MR) analysis, using genetic variants as instrumental variables. A two-sample MR analysis was performed, employing Inverse Variance Weighted (IVW) as the primary method, supported by weighted median, MR-Egger regression, MR-PRESSO, and MR robustness-adjusted contour scores. Data were obtained from the International Exercise Genetics Database (IEGD) and the Global Diabetes Research Consortium (GRC), encompassing over 150,000 individuals for exercise intensity and around 200,000 T2D patients and controls. SNPs linked to exercise intensity were selected based on genome-wide significance (P < 5 × 10^-8) and linkage disequilibrium criteria (distance >10,000kb, r^2 < 0.001). The IVW analysis suggested that high-intensity exercise might reduce T2D risk, but the association was not statistically significant (OR = 0.667, 95% CI = 0.104-4.255, P = 0.667). The wide confidence interval indicates uncertainty in the effect estimate. Low-intensity exercise showed no significant effect on T2D risk (OR ∼ 1.0). Sensitivity analyses, including weighted median and MR-Egger regression, confirmed no significant association between high-intensity exercise and T2D risk. The MR-PRESSO analysis found no significant outliers, and the global test for pleiotropy was non-significant (P = 0.455). Cochran's Q test for heterogeneity in the IVW analysis was non-significant (Q = 12.45, P = 0.234), indicating consistency among SNP-derived estimates. High-intensity exercise potentially reduces T2D risk, but the association is not statistically significant. Further research is needed to understand the complex relationship between exercise intensity and T2D.

The Effects of Blood Flow Restriction Aerobic Exercise on Body Composition, Muscle Strength, Blood Biomarkers, and Cardiovascular Function: A Narrative Review.

Blood flow restriction exercise has emerged as a promising alternative, particularly for elderly individuals and those unable to participate in high-intensity exercise. However, existing research has predominantly focused on blood flow restriction resistance exercise. There remains a notable gap in understanding the comprehensive effects of blood flow restriction aerobic exercise (BFRAE) on body composition, lipid profiles, glycemic metabolism, and cardiovascular function. This review aims to explore the physiological effects induced by chronic BFRAE. Chronic BFRAE has been shown to decrease fat mass, increase muscle mass, and enhance muscular strength, potentially benefiting lipid profiles, glycemic metabolism, and overall function. Thus, the BFRAE offers additional benefits beyond traditional aerobic exercise effects. Notably, the BFRAE approach may be particularly suitable for individuals with low fitness levels, those prone to injury, the elderly, obese individuals, and those with metabolic disorders.

Effects of High-Intensity Intermittent Training on Metabolic Parameters and Irisin Levels in High-Fat-Fed Rats

Objective: To investigate the effects of high-intensity intermittent training (HIIT) on preventing significant weight gain and provide scientific theoretical support and practical guidance for reducing the occurrence of obesity. Methods: Twenty-four Sprague-Dawley rats were randomly divided into four groups: the control sedentary group (CS), the high-fat sedentary group (HS), the high-fat continuous exercise group (HE), and the high-fat intermittent exercise group (HI). The HE and HI groups underwent five days of continuous low-intensity exercise and eight weeks of high-intensity intermittent exercise. Weekly monitoring included measurements of food intake and body weight. An automatic biochemical analyzer was used to assess blood lipid and glucose levels, while ELISA kits measured serum insulin and irisin content. H&amp;E staining was used to observe adipocyte size. Results: In the HS group, body weight, blood lipid levels, blood glucose levels, and adipocyte size significantly increased, while the QUICKI index decreased. In the HI group, body weight, blood lipid levels, blood glucose levels, and adipocyte size decreased, and the QUICKI index increased. The effects of high-intensity intermittent exercise were superior to those of continuous low-intensity exercise. In the HI group, serum irisin levels did not change significantly after exercise, while in the HE group, there was a slight upward trend in irisin levels. Conclusion: A high-fat diet induced abnormal metabolism in rats. HIIT effectively prevents metabolic abnormalities induced by a high-fat diet, and its effects are more pronounced than those of low-intensity exercise. HIIT stimulates the secretion of blood irisin, affecting secretion levels, and may represent a novel mechanism for maintaining metabolic homeostasis. This has important implications for controlling significant weight gain.

High-intensity interval training improves cardiovascular and physical health in patients with rheumatoid arthritis: a multicentre randomised controlled trial

ObjectivesPatients with rheumatoid arthritis (RA) have substantially elevated risk for cardiovascular diseases, and low cardiorespiratory fitness (VO2max) is a major mediator. The aim of this assessor-blinded, two-armed multicentre randomised controlled...

The Effects of L-citrulline Supplementation on the Athletic Performance, Physiological and Biochemical Parameters, Antioxidant Capacity, and Blood Amino Acid and Polyamine Levels in Speed-Racing Yili Horses.

The objective of this study was to evaluate the effects of pre-exercise L-citrulline supplementation on the athletic performance of Yili speed-racing horses during a high-intensity exercise. On the 20th day of the experiment, blood samples were collected at 3 h and 6 h post-supplementation to measure the amino acid and polyamine concentrations. On the 38th day of the experiment, the horses participated in a 2000 m speed race, and three distinct blood samples were gathered for assessing blood gases, hematological parameters, the plasma biochemistry, antioxidant parameters, and NO concentrations. The results indicate that the L-citrulline group showed a significant increase in the plasma citrulline and arginine concentrations. Conversely, the concentrations of alanine, serine, and threonine were significantly decreased. The glycine concentration decreased significantly, while there was a trend towards an increase in the glutamine concentration. Additionally, the levels of putrescine and spermidine in the plasma of the L-citrulline group were significantly increased. In terms of exercise performance, L-citrulline can improve the exercise performance of sport horses, significantly reduce the immediate post-race lactate levels in Yili horses, and accelerate the recovery of blood gas levels after an exercise. Furthermore, in the L-citrulline group of Yili horses, The levels of the total protein of plasma, superoxide dismutase, catalase, and lactate dehydrogenase were significantly increased both 2 h before and 2 h after the race. The total antioxidant capacity showed a highly significant increase, while the malondialdehyde content significantly decreased. In the immediate post-race period, the creatinine content in the L-citrulline group significantly increased. In conclusion, this study demonstrates that L-citrulline supplementation can influence the circulating concentrations of L-citrulline and arginine in Yili horses, enhance the antioxidant capacity, reduce lactate levels, and improve physiological and biochemical blood parameters, thereby having a beneficial effect on the exercise performance of athletic horses.

Impact and effect of preoperative short-term preoperative pulmonary-related training on patients with gastric cancer: a randomized controlled single center trial

PurposeThis study aimed is to evaluate the impact of pre- and postoperative pulmonary-related training, including respiratory and aerobic training, on postoperative pulmonary complications (PPCs) after radical resection of gastric cancer (GC). MethodsWe conducted a randomized controlled trial of 121 participants who received a systematic, comprehensive, high-intensity pulmonary exercise regimen for 5 days preoperatively and at least 5 days postoperatively. The control group received standard preoperative care. We analyzed the occurrence of PPCs in both groups as the primary outcome ResultsA total of 43 of 121 participants (35.5%) were diagnosed as having PPCs, and the incidence of PPCs was markedly lower in the training group than in the control group (26.2% [16 of 61] vs 45.0% [27 of 60]; P = .031). Moreover, the duration of the postoperative hospital stay was shorter in the training group (8.69 ± 1.92 days) than the control group (9.57 ± 2.16 days; P = .020) and reduced hospitalization costs, amounting to €9605.1 ± €2556.26 in the training group and €10,594.6 ± €2560.7 in the control group (P = .035). ConclusionOur study established that a perioperative pulmonary-related training notably diminishes the incidence of PPCs, curtails the duration of hospitalization, and mitigates hospitalization expenses for patients undergoing GC surgery.

Recovery of heart rate and heartrate variability after a maximal cardiopulmonary exercise test in novice female runners.

Previous studies have shown delayed cardiac vagal reactivation after high-intensity endurance exercise when estimated with heartrate variability (HRV). However, the recovery dynamics of RR intervals (RRI) and HRV after a maximal incremental exercise test have been studied less in non-athletic population and especially in females. The main aim of the study was to examine the recovery dynamics of RRI and HRV immediately after a maximal cardiopulmonary exercise test (CPET) in adult females. Twenty-eight healthy, novice recreational female runners (33.7 ± 4.2years) were selected to participate in this study from a larger group of participants (Run RCT). RRIs were collected continuously during a controlled rest, a CPET on a treadmill and a 15-min controlled, passive recovery. Minute-by-minute recovery dynamics were analyzed. The dynamic phase of RRI and heart rate recovery (HRR) (from 192.2 ± 9.9 to 111.4 ± 2.4, P < 0.001) occurred during the first 4.5min with HRR of 36 ± 10 beats during the first minute of the recovery. Resting heart rate was negatively associated (r = - 0.53, P = 0.016) with HRR during the recovery. No recovery of root mean square of successive RRIs (RMSSD) was detected during the 15-min recovery. RMSSD was 15.0 ± 9.2% of resting values at the end of the recovery. No recovery of vagal-derived HRV was detected immediately after a CPET in novice recreational female runners despite marked changes in sympathovagal balance, detected by rapid recovery of RRI during the first 5min after exercise cessation.

Physiological effects of high-flow nasal cannula during sustained high-intensity exercise in healthy volunteers: a randomised crossover trial

IntroductionHigh-flow nasal cannula (HFNC) has increased exercise capacity in patients with chronic respiratory diseases. However, it remains unknown whether HFNC impacts respiratory physiological variables during exercise. This study aimed to evaluate the effect of HFNC on respiratory physiological variables during sustained high-intensity exercise in healthy volunteers.MethodsWe performed a single-center, open-label, and randomised crossover trial to compare HFNC (60 L·min−1) and Sham-HFNC (2 L·min−1) interventions during a constant work-rate exercise (CWRET) through randomised order. The primary outcome was ΔPes, and the secondary outcomes were other variables of inspiratory effort, ventilation distribution, ventilatory variables, and clinical assessment. We evaluated volunteers at seven-time points (Baseline= T0; CWRET= T1-T2-T3 (minutes: 1′, 4′ and 6′); Cooldown-period= T4-T5-T6 (minutes: 1′; 6′;10′)) in both interventions.ResultsFourteen healthy volunteers (50% women; age: 22 [21–27] years) were enrolled. Mean differences in ΔPes decreased to favor the HFNC intervention compared to Sham-HFNC at T2 (−2.8 cmH2O; 95%CI −5.3 to −0.3), as well as the sPTPmin at T2 (−86.1 cmH2O×s·min−1;95%CI −146.2 to −26.1), and T3 (−79.9 cmH2O×s·min−1;95%CI −142.3 to −17.6). The standard deviation of the regional ventilation delay index was also lower with HFNC compared to Sham-HFNC (T1: −1.38; 95%CI −1.93 to −0.83; T2: −0.71; 95%CI −1.27 to −0.16). There was decreased dyspnea to favor the HFNC, but sPTP-per-breath, spatial distribution ventilation indexes, ventilatory variables, and clinical assessments were nonsignificant between interventions.ConclusionHFNC intervention reduces respiratory effort, dyspnea and improves temporal ventilation distribution in healthy volunteers during CWRET.

Combined Impact of Heart Rate Sensor Placements with Respiratory Rate and Minute Ventilation on Oxygen Uptake Prediction.

Oxygen uptake (V˙O2) is an essential metric for evaluating cardiopulmonary health and athletic performance, which can barely be directly measured. Heart rate (HR) is a prominent physiological indicator correlated with V˙O2 and is often used for indirect V˙O2 prediction. This study investigates the impact of HR placement on V˙O2 prediction accuracy by analyzing HR data combined with the respiratory rate (RESP) and minute ventilation (V˙E) from three anatomical locations: the chest; arm; and wrist. Twenty-eight healthy adults participated in incremental and constant workload cycling tests at various intensities. Data on V˙O2, RESP, V˙E, and HR were collected and used to develop a neural network model for V˙O2 prediction. The influence of HR position on prediction accuracy was assessed via Bland-Altman plots, and model performance was evaluated by mean absolute error (MAE), coefficient of determination (R2), and mean absolute percentage error (MAPE). Our findings indicate that HR combined with RESP and V˙E (V˙O2HR+RESP+V˙E) produces the most accurate V˙O2 predictions (MAE: 165 mL/min, R2: 0.87, MAPE: 15.91%). Notably, as exercise intensity increases, the accuracy of V˙O2 prediction decreases, particularly within high-intensity exercise. The substitution of HR with different anatomical sites significantly impacts V˙O2 prediction accuracy, with wrist placement showing a more profound effect compared to arm placement. In conclusion, this study underscores the importance of considering HR placement in V˙O2 prediction models, with RESP and V˙E serving as effective compensatory factors. These findings contribute to refining indirect V˙O2 estimation methods, enhancing their predictive capabilities across different exercise intensities and anatomical placements.

Liver Function Markers Response to Different Exercise Intensities in Athletes A Single Bout Perspective

Exercise provides considerable health advantages through promoting proper body system functioning, healthy growth and development, and quality of life. The present study investigated the effect of single bout High- Intensity Exercise (HIE) compared to Low-Intensity Exercise (LIE) on liver function markers in athletes. This cross-sectional study was carried out in the Department of Physical Education, Banaras Hindu University, Varanasi (UP). A total of 20 healthy male athletes with age range from 22 to 26 years were randomly selected and underwent 5 minutes of HIE and LIE separated by one week. Blood samples for selected liver function markers were taken pre-exercise, immediately, 10 and 20 minutes post-HIE and LIE, respectively. A repeated measures ANOVA with greenhouse-geisser correction found a significant difference between high and low intensity exercises for SGOT (F=5.881; p&lt;0.05) and SBT (F=7.154; p&lt;0.05) values, while statistically insignificant in the case of SGPT (F=1.572; p&gt;0.05). In high intensity exercise there was statistically significant difference for SGOT (F=7.564; p&lt;0.05) value between different time points. Post hoc analysis with a bonferroni correction showed that SGOT value was significantly increased immediately after the HIE, reducing 10 minutes after the exercise and closely returned to baseline level after 20 minutes of exercise, whereas LIE showed no significant changes. Exercise intensity is important as it triggers liver pathology by asymptomatic modifying liver function markers. These findings can be used to develop and administer exercise training plans for athletes.

High-intensity intermittent exercise increases serum levels of chitinase 3-like protein-1 and matrix metalloproteinase-9 in persons with multiple sclerosis

The study aimed to evaluate the effect of high-intensity intermittent exercise (HIIE) on serum levels of MMP-9 and CHI3L1 in multiple sclerosis. Study group received HIIE twice a week for 12 weeks, while control group received no treatment. In intra-group comparison, study group showed a significant increase in MMP-9 and CHI3L1 levels, while control group showed no significant difference. In intergroup comparison, a significant difference was found only in CHI3L1 levels after treatment. The increase in MMP-9 and CH3L-1 concentrations in study group suggests that these biomarkers may play a role in regulating specific skeletal muscle adaptations due to HIIE.

Exercise-Induced Cardiac Troponin I Elevation Is Associated With Regional Alterations in Left Ventricular Strain in High-Troponin Responders.

The implications of exercise-induced cardiac troponin elevation in healthy individuals are unclear. This study aimed to determine if individuals with a high exercise-induced cardiac troponin I (cTnI) response have alterations in myocardial function following high-intensity endurance exercise compared with normal-cTnI responders. Study individuals were recruited from previous participants in a 91-km mountain bike cycling race (the North Sea Race) and were classified as high- (n=34) or normal-cTnI responders (n=25) based on maximal cTnI values after the recruitment race. The present study exposed all participants to 2 prolonged high-intensity exercises: a combined lactate threshold and cardiopulmonary exercise test and repeated participation in the North Sea Race. Echocardiography was performed before, immediately after, and 24 hours following exercise. All study individuals (n=59) had normal coronary arteries, and were aged 51±10 years; 46 (74%) were men. There were no differences in baseline characteristics between the high- and normal-cTnI responders. Maximal cTnI levels 3 hours after exercise were significantly higher in the high- compared with normal-cTnI group (P<0.001-0.027). Following exercise, there were no differences in global ventricular function between the 2 groups. In contrast, high-cTnI responders had significantly lower regional strain in the anteroseptal segments following exercise, with more profound changes after the race. High-cTnI responders had lower anteroseptal segmental strain shortly after exercise than normal-cTnI responders. However, there were no permanent alterations in myocardial strain, indicating no short- or long-term adverse consequences of these exercise-induced alterations in myocardial function. URL: https://www.clinicaltrials.gov; Unique identifier: NCT02166216.

Impact of exercise and fasting on mitochondrial regulators in human muscle

Abstract Objectives To investigate the impact of acute energetic stress (acute HIIE and fasting) on ERRγ, PPARβ, NR1D1, NR4A1, and TFEB in human skeletal muscle. Methods The current study performed secondary analyses using muscle biopsy samples from two previously published studies: study 1) leg muscle biopsies from nine men and eight women were obtained pre and 3 h following acute high-intensity interval cycling exercise (HIIE); study 2) leg muscle biopsies were obtained from nine men pre-, during, and post-an 8 h fast with or without 2 h of arm ergometer exercise. RT-PCR was performed on samples from each study to determine the mRNA expression of ERRγ, PPARβ, NR1D1, NR4A1, and TFEB. Additionally, we retrieved data from meta-analyzed human muscle gene expression using the publicly available database MetaMex. Results PGC-1α (p&lt;0.01, d=1.98) and NR4A1 (p&lt;0.01, d=1.36) mRNA expression significantly increased while TFEB (p≤0.05, d=0.70) decreased following HIIE. Significant decreases in NR4A1 and NR1D1 mRNA expression were observed following an 8 h fast. Our MetaMex analyses revealed significant increases (p&lt;0.05) in PGC-1α and NR4A1 expression following aerobic and resistance exercise, and in PPARβ expression following resistance exercise. Conclusions Our data indicate that acute HIIE stimulates increases in NR4A1 and PGC-1α and decreases in TFEB mRNA expression in human skeletal muscle. Additionally, a short term (8 h) fast reduced the mRNA expression of the transcriptional regulators NR4A1 and NR1D1 – potentially as a mechanism of decreasing mitochondrial biogenesis to reduce energy expenditure during a period of restricted energy availability.

Precision and accuracy of four handheld blood lactate analyzers across low to high exercise intensities.

To evaluate the precision and accuracy in measured blood lactate concentrations among four commonly used handheld lactate analyzers compared to two stationary analyzers. Venous blood samples were taken at exercise intensities ranging from low to high. The blood lactate concentration was measured simultaneously with four pairs of handheld lactate analyzers (two new units of each brand: Lactate Plus, Lactate Pro2, Lactate Scout 4, and TaiDoc TD-4289), and compared with two stationary analyzers (Biosen C-Line and YSI Sport 1500). Measurements were repeated for a range of blood lactate concentrations (measured with Biosen) from 0.88 to 4.89mM with a median difference between measurements of 0.10 mM. The mean relative differences to the Biosen analyzer were 7% (Plus), 7% (Pro), 10% (Scout), 42% (Tai), and 32% (Ysi). The residual standard errors after linear regression against Biosen were 0.18 mM (Plus), 0.20 mM (Pro), 0.22 mM (Scout), 0.15 mM (Tai), and 0.06 mM (Ysi). Accordingly, a blood lactate concentration of 3mM measured with Biosen yielded 95% prediction intervals that were 0.72 mM (Plus), 0.80 mM (Pro), 0.87 mM (Scout), 0.60 mM (Tai), and 0.23 mM (Ysi) wide. Compared to our two stationary analyzers, the precision of the four handheld lactate analyzers evaluated in this study was poor. Among the four, Tai was the most precise; however, this analyzer had low accuracy with a substantial mean difference to the reference analyzer.

Effect of Low vs. High Carbohydrate Intake after Glycogen-Depleting Workout on Subsequent 1500 m Run Performance in High-Level Runners.

Carbohydrate (CHO) metabolism is crucial for short-duration, high-intensity exercise performance, but the effects of variations in glycogen availability have not been investigated in field trials of trained athletes. This study was designed to test how 1500 m time trial (TT) performance is affected by the manipulation of pre-race glycogen reserves. Competitive middle-distance runners (n = 11 (4 females)) completed a 1500 m individually paced indoor TT after abundant (high, >5 g/kg/d) or restricted (low, <1.5 g/kg/d) dietary CHO intake for 2 days after a glycogen-depleting session. Stride pattern, heart rate (HR), capillary blood lactate, and glucose and plasma malondialdehyde (MDA) response were determined. The TT was slower in low vs. high condition by 4.5 (4.5) s (~2%; p < 0.01), with a tendency toward shorter stride length. Blood lactate and glucose were lower before the TT in low vs. high condition (1.8 (0.5) vs. 2.2 (0.7) mmol/L and 5.4 (0.7) vs. 5.9 (0.8) mmol/L, p = 0.022 and 0.007, respectively), and peak lactate was higher in high vs. low condition (16.8 (3.1) vs. 14.5 (4.2) mmol/L, p = 0.039). Plasma MDA was the same before the TT, and 15 min after the TT, it increased similarly by 15% in low (p = 0.032) and high (p = 0.005) conditions. The restriction of pre-test CHO intake impaired 1500 m TT performance and reduced baseline and peak blood lactate concentrations but not blood glucose or MDA response.

Dietary and activity habits associated with hypertension in Kunming school-aged children and adolescents: A multilevel analysis of the study of hypertension risks in children and adolescents

ObjectiveHypertension has become a public health challenge for Yunnan children and adolescents. The study aims is to assess the dietary and activity habits associated with hypertension in Kunming children and adolescents and to develop effective strategies for preventing and controlling, Southwest China. MethodsConducted in 2019, the cross-sectional study involved 3,150 students, aged 13.25 ± 2.77 years, multistage, stratified, randomly sampled from Chenggong and Fumin areas, Southwest China. ResultsAmong 3,150 participants, 6.19 % never drank milk, 3.46 % never consumed fresh fruit. 2.67 % never consumed fresh vegetables, 2.48 % never ate breakfast and 10.06 % frequently drank sugary beverages (soft drinking). Additionally, 21.56 % engaged in moderate-intensity exercise less than one Day a week, and 31.97 % performed high-intensity exercise less than one Day a week. The intraclass correlation coefficient indicated that 49.40 % of the total variance was attributed to the dietary level and 42.10 % was attributed to the activity level. Eating fresh vegetables and fruit, taking physical education classes they attended per week and the frequency of moderate-intensity and high-intensity exercise per week were independent protective factors for hypertension (P < 0.01); drinking sugary beverages (soft drinking) was a independent risk factor against hypertension (P < 0.05); breakfast skipping was a possible risk factor for hypertension (P < 0.15). No significant associations were found with fried food or sweet food weekly consumption (P < 0.15). ConclusionsThe hypertension of children and adolescents cannot be ignored in Kunming, Southwest china. Dietary and activity factors are modifiable. We should make comprehensive child-friendly health education materials as soon as possible.