Football is a high-intensity intermittent sport in which glycolytic metabolism plays a critical role in the sprint performance of football players. Therefore, this study aimed to compare pure maximal glycolytic rate (PνLa.max), and metabolic contributions across different positions in highly trained football players. Thirty male highly trained football players were recruited and classified into three positional groups: forward (FW, n = 10), midfielder (MF, n = 10), and defender (DF, n = 10). All participants completed three exercise tests, each performed either on a 127-meter indoor track or within a laboratory setting. During the 10-second maximal sprint test (10-s MST), oxygen uptake and blood lactate concentrations (La⁻) were measured and used to determine PνLa.max and metabolic contributions (phosphagen; WPCr, glycolytic; WGly, and oxidative; Woxi). Additionally, maximal oxygen uptake ([Formula: see text]O₂max), lactate thresholds (LTs), and running speeds at specific La⁻ values were assessed using a ramp and step test on a motorized treadmill. PνLa.max values were significantly greater in FW and DF compared to MF (P = 0.0065, d = 1.60, d = 1.55, respectively). Peak La- (P = 0.0044, d = 1.74; P = 0.0046, d = 1.65), ΔLa- (P = 0.0067, d = 1.59; P = 0.0099, d = 1.57), and WGly (P = 0.0296, d = 1.49; P = 0.0105, d = 1.50) measured in kJ during the 10-s MST were also elevated for FW and DF relative to MF. No significant differences were observed in [Formula: see text]O₂max or LTs among the groups. Moreover, a moderate positive correlation was found between PνLa.max and sprint distance attained during the 10-s MST. The assessment of PνLa.max enables a more accurate characterization of positional demands and may aid in the formulation of position-specific training interventions.
This study develops a numerical framework for optimizing microseismic sensor network layouts in the Woxi Mine. Three candidate deployment schemes were evaluated by combining synthetic arrival-time perturbations with the classical Geiger localization algorithm under different uncertainty levels. The results show that localization performance is governed primarily by sensor layout geometry, which controls both the magnitude and the spatial distribution of localization errors. Event-wise robustness analysis indicates that the layout with the lowest overall localization error is not necessarily the one with the strongest spatial enclosure. These findings provide a geometry-based reference for the preliminary design and subsequent refinement of a mine-scale microseismic monitoring system in deep underground engineering.
Acoustic emission (AE) source localization provides important spatial information for damage characterization and fracture evolution analysis in construction materials, while its accuracy and applicability are strongly dependent on sensor network design. This study proposes an optimization framework for selecting an effective six-sensor network for velocity-free AE source localization in construction materials. The source coordinates are determined by solving a nonlinear inverse problem using the Levenberg-Marquardt algorithm, and candidate sensor subsets are evaluated by combining location error metrics with the number of effective localization results to quantify the effective monitoring range for damage characterization. The framework is investigated through numerical simulations and pencil-lead break tests on a 600 mm × 600 mm ceramic tile. Among different six-sensor configurations, the best-performing layouts place four sensors at the outer corners and two sensors at the horizontal or vertical inner corners. A benchmark comparison with the Fisher-information-based optimized sensor network and sensitivity analyses further show that the optimized sensor network maintains higher effective monitoring ranges under arrival-time noise, velocity uncertainty, and sensor coordinate perturbations. The proposed approach provides a useful reference for robust and cost-effective AE sensor network design in damage monitoring, fracture characterization, and nondestructive evaluation of construction materials.
Objective: To evaluate the application value of portable pulse oximeter in adult obstructive sleep apnea (OSA). Methods: This study prospectively enrolled adult patients who underwent polysomnography (PSG) due to snoring at the Respiratory and Sleep Medicine Department of Peking University People's Hospital from July 2022 to July 2023. During PSG monitoring, CS-WOxi was continuously used to monitor blood oxygen levels. The consistency between 3% oxygen desaturation index (ODI3) measured by portable pulse oximeter and ODI3 of polysomnography was evaluated using difference test, Pearson's correlation coefficient, and Bland-altman method. Receiver operating characteristic curve was used to determine the optimal threshold for diagnosing OSA. Results: A total of 184 subjects were included, including 121 males (65.8%) and 63 females (34.2%). The mean age was 46.0 (34.3, 59.0) years, body mass index was 26.0 (23.3, 29.6) kg/m², and the apnea-hypopnea index was 18.2 (5.8, 40.8) events/h. There was a significant difference between CS-ODI3 and PSG-ODI3 [17.1(6.2, 42.7) vs. 14.0(2.9, 32.6), P<0.001], and the Pearson correlation coefficient was 0.93 (P<0.001). There was a good correlation between CS-ODI3 and PSG-AHI (r=0.92, P<0.001). Bland-Altman consistency test showed that the average difference between the two was 0.7 events/h, and the 95% consistency limit was (-17.9, 19.3 events/h). When the CS-ODI3≥5 events/h was used to identify OSA, the sensitivity was 94.4%, the specificity was 80.0%, and the accuracy was 91.3%. When PSG-AHI≥5 events/h was used as the diagnostic criteria, the area under the receiver operating characteristic curve was 0.933. Conclusion: Portable pulse oximeter can monitor pulse oxygen saturation accurately and has good sensitivity and specificity for OSA high-risk patients, and is a reliable tool for OSA screening. 目的： 评价便携式脉搏血氧仪（CS-WOxi）在成人阻塞性睡眠呼吸暂停（OSA）中的应用价值。 方法： 本研究前瞻性纳入2022年7月至2023年7月因打鼾就诊于北京大学人民医院呼吸睡眠医学科进行多导睡眠监测（PSG）的成人患者，在PSG监测时同步使用CS-WOxi持续监测经皮动脉血氧饱和度（SpO2）。利用差异性检验、Pearson相关系数及Bland-Altman法评估CS-WOxi测得的3%氧减指数（CS-ODI3）与PSG测得的3%氧减指数（PSG-ODI3）之间的一致性，并以受试者工作特征（ROC）曲线确定其诊断OSA的最佳界值。 结果： 共纳入184例受试者，其中男性121例（65.8%），女性63例（34.2%），年龄为46.0（34.3，59.0）岁，体重指数（BMI）为26.0（23.3，29.6）kg/m²，呼吸暂停低通气指数（AHI）为18.2（5.8，40.8）次/h。CS-ODI3与PSG-ODI3之间差异有统计学意义［17.1（6.2，42.7）次/h比14.0（2.9，32.6）次/h，P<0.001］，两者相关系数为0.93（P<0.001）。CS-ODI3与PSG测得的AHI（PSG-AHI）之间相关性较好（r=0.92，P<0.001），Bland-Altman一致性检验显示两者平均差值为0.7次/h，95%一致性界限为（-17.9，19.3次/h）。当使用CS-ODI3≥5次/h来识别OSA时，敏感度为94.4%，特异度为80.0%，准确率为91.3%。以PSG作为金标准时，CS-ODI3诊断OSA（PSG-AHI≥5次/h）的ROC曲线下面积（AUC）为0.933。 结论： 便携式脉搏血氧仪对于OSA高风险患者SpO2指标监测较准确，识别OSA有较好的敏感度和特异度，是可用于筛查的可靠工具。.
This study compared the physiological profiles and energy-system contributions of trained football players engaged in regular-passing and third-man-passing small-sided games (SSGs) that included 4 versus 4 and a goalkeeper. Ten male trained football players participated in this crossover study. All participants were randomly assigned to either regular-passing SSG or third-man-passing SSG (4 vs 4 with a goalkeeper, 35-m × 17-m pitch size, and 6-min match duration). During these SSGs, physiological parameters including peak and mean heart rate, oxygen uptake (V˙O2peak and V˙O2mean), metabolic equivalents in V˙O2peak and V˙O2mean, and blood lactate concentrations (peak La- and delta La- [Δ La-]), were measured. Energy contributions (oxidative [WOxi], glycolytic [WGly], and phosphagen [WPCr] systems) and Global Positioning System (GPS) variables (total distance, total acceleration counts, mean speed, and maximum speed) were also analyzed. No significant differences in physiological parameters and GPS variables were found between regular- and third-man-passing SSGs. WOxi in kilojoules and percentages was significantly higher during both SSGs than WPCr and WGly (P < .0001, respectively). WPCr and WPCr + WGly values during third-man-passing SSGs were significantly higher than those during regular-passing SSGs (P < .05). Additionally, low to moderate positive correlations were observed between WOxi, WGly in kilojoules, V˙O2peak, V˙O2mean, peak La-, Δ La-, total acceleration counts, and mean speed (r = .39-.64). Third-man-passing SSGs may be useful for increasing anaerobic capacity. More third-man-passing SSG sessions in preparation for football games may support high metabolic power and repeated powerful anaerobic performances in trained football players.
The aim of this study was to investigate physiological responses and energetic contributions during simulated epée matches in elite fencers. Ten elite male fencers participated in simulated epée (direct elimination) matches. Simulated epée matches included 3 bouts of 3 minutes each with 1-minute rests between bouts. During these sessions, physiological variables such as mean and peak heart rate, peak and mean oxygen uptake (VO2peak and VO2mean), metabolic equivalents of task in VO2peak and VO2mean, and blood lactate concentrations (peak lactate concentration and delta blood lactate concentration) were measured. Furthermore, energetic contributions (oxidative [WOxi], glycolytic, and phosphagen) and time-motion variables were estimated. Values of peak heart rate, mean heart rate, and WOxi (in percentages) were significantly higher in the second and third bouts compared with the first. VO2peak and metabolic equivalents of task in VO2peak were significantly higher in the first bout compared with the third bout. Values of delta blood lactate concentration and glycolytic contribution (in kilojoules and percentages) were significantly lower in the second and third bouts compared with the first. VO2mean and metabolic equivalents of task in VO2mean were significantly higher in the second bout compared with the third bout. Furthermore, WOxi (in kilojoules and percentage) was significantly higher in all bouts compared with phosphagen and glycolytic contributions. Low positive and negative correlations were seen between WOxi, VO2mean, sum of attacks and defense times, and the sum of time without attacks and defenses. Direct-elimination epée matches consist of high-intensity intermittent exercise, and the oxidative contribution is 80% to 90%. Improving aerobic conditioning may support high-intensity intermittent actions during entire epée matches in elite fencers.
Metabolic flexibility includes the ability to perform fat and carbohydrate oxidation, as well as oxidative capacity, which is associated with mitochondrial function, energetic contributions, and physical health and performance. During a session of graded incremental exercise testing (GIET), we investigated metabolic flexibility, the contributions of three energy systems, and performances of individuals with different metabolic characteristics. Fifteen general population (GP; n = 15, male n = 7, female n = 8) and 15 national-level half-marathon and triathlon athletes (A; n = 15, male n = 7, female n = 8) participated in this study. During GIET, heart rate (HR), oxygen uptake (V˙O2mean and V˙CO2mean), metabolic equivalents (METs) in V˙O2mean, and blood glucose and lactate concentrations (La-) were measured. Furthermore, jogging/running speeds (S) at specific La-, fat and carbohydrate oxidations (FATox and CHOox), and energetic contributions (oxidative; WOxi, glycolytic; WGly, and phosphagen; WPCr) were calculated. The percentages of HRmax, relative V˙O2mean, V˙CO2mean, and METs in V˙O2mean were all lower in A than they were in GP. FATox values were lower in GP than in A, while CHOox and La- were higher in GP than in A. Negative correlations between La- and FATox were also observed in both groups. Contributions of WOxi, WGly, and WPCr were higher in GP than in A during GIET. Moreover, values of WGly, and WPCr were significantly lower and higher, respectively, in male GP than in female GP. Furthermore, S at specific La- were higher in A than in GP. It is suggested that an individualized low-intensity recovery exercise program be established, to achieve increased metabolic flexibility and oxidative capacity (aerobic base), such as public health improvements and a greater volume of higher exercise intensities; this is the type of exercise that elite athletes worldwide mostly perform during their training period and progression. This may prevent cardiac/metabolic diseases in GP.
Purpose: The objective of this study was to investigate metabolic energy contributions during high-intensity hatha yoga (HIHY) and to compare changes in physiological variables between active and passive recovery methods. Methods: The study involved 20 women yoga instructors (n = 20) who performed 10 min of HIHY (vigorous sun salutation). Upon completion, they were randomly assigned to either active (walking; n = 10) or passive (savasana; n = 10) recovery groups for a period of 10 min. During HIHY, physiological variables such as heart rate (HRpeak and HRmean), oxygen uptake (VO2peak and VO2mean), and blood lactate concentrations (peak La-) were measured. Energetic contributions (phosphagen; WPCR, glycolytic; WGly, and oxidative; WOxi) in kJ and % were estimated using VO2 and La- data. Furthermore, the metabolic equivalents (METs) of VO2peak and VO2mean were calculated. To compare different recovery modes, HRpost, ΔHR, VO2post, ΔVO2, recovery La-, and recovery ΔLa- were analyzed. Results: The results revealed that HRpeak, VO2peak, and peak La- during HIHY showed no differences between the two groups (p > 0.05). Values of HRpeak, HRmean, METs of VO2peak and VO2mean, and La- during HIHY were 95.6% of HRmax, 88.7% of HRmax, 10.54 ± 1.18, 8.67 ±.98 METs, and 8.31 ± 2.18 mmol·L-1, respectively. Furthermore, WOxi was significantly higher compared with WPCR, WGly, and anaerobic contribution (WPCR + WGly), in kJ and % (p < 0.0001). VO2post and recovery ΔLa- were significantly higher in the active recovery group (p < 0.0001, p = 0.0369, respectively). Values of ΔVO2 and recovery La- were significantly lower in the active group compared with the passive group (p = 0.0115, p = 0.0291, respectively). Conclusions: The study concluded that high-intensity hatha yoga which was performed for 10 min is a suitable option for relatively healthy people in the modern workplace who may have hatha yoga experience but do not have time to perform a prolonged exercise. Following active recovery, they can participate in further HIHY sessions during short breaks. Furthermore, a faster return to work can be supported by physiological recovery.
To investigate the effect of sodium bicarbonate (NaHCO3) on performance and estimated energy system contribution during simulated taekwondo combat. Nine taekwondo athletes completed two experimental sessions separated by at least 48 h. Athletes consumed 300 mg/kg body mass of NaHCO3 or placebo (CaCO3) 90 min before the combat simulation (three rounds of 2 min separated by 1 min passive recovery), in a double-blind, randomized, repeated-measures crossover design. All simulated combat was filmed to quantify the time spent fighting in each round. Lactate concentration [La-] and rating of perceived exertion (RPE) were measured before and after each round, whereas heart rate (HR) and the estimated contribution of the oxidative (WOXI), ATP (adenosine triphosphate)-phosphocreatine (PCr) (WPCR), and glycolytic (W[La-]) systems were calculated during the combat simulation. [La-] increased significantly after NaHCO3 ingestion, when compared with the placebo condition (+14%, P = 0.04, d = 3.70). NaHCO3 ingestion resulted in greater estimated glycolytic energy contribution in the first round when compared with the placebo condition (+31%, P = 0.01, d = 3.48). Total attack time was significantly greater after NaHCO3 when compared with placebo (+13%, P = 0.05, d = 1.15). WOXI, WPCR, VO2, HR and RPE were not different between conditions (P > 0.05). NaHCO3 ingestion was able to increase the contribution of glycolytic metabolism and, therefore, improve performance during simulated taekwondo combat.