递增强度运动过程中NIRS肌氧拐点在评价人体最大有氧能力中的作用

应用近红外光谱技术(NIRS)测定肌肉递增强度工作时肌氧含量变化与最大摄氧量和无氧阈指标之间的关系;分析肌氧拐点与无氧阈拐点产生的机制及在测定最大有氧能力中的作用。方法:受试者17名按运动水平分为A、B两组在功率自行车上以逐级递增负荷蹬车,测定右股外侧肌肌氧含量并同步测量VE、VCO2、VO2、HR,并在每级负荷末测定血乳酸。结果:研究发现递增负荷运动时肌氧含量呈台阶状下降,负荷较低时,肌氧在负荷开始阶段迅速下降之后保持平衡或升高,负荷较高时肌氧持续下降,肌氧的变化与血容量相吻合。肌氧含量与摄氧量、心率及血乳酸等值高度相关(P<0.01)。肌氧下降时出现拐点与乳酸阈、通气阈拐点基本一致。结论:研究表明NIRS测定动态肌肉收缩时肌氧含量变化对运动强度具有较高敏感性;肌氧拐点与通气无氧阈、心率无氧阈、乳酸阈在时间和强度上相一致,表明肌氧含量的测定可以用于人体最大有氧能力的评定。     

近红外光谱技术监测赛艇运动员有氧代谢能力的研究

应用NIRS技术无损监测赛艇运动员在递增负荷运动时骨骼肌氧含量的相对变化,并同步监测受试者气体代谢部分指标的变化特征,分析二者之间的相关关系,以期为运动员有氧代谢能力的评定寻求新的检测方法与手段。结果表明,肌氧含量的相对变化能较好地反映出运动负荷的变化,因而肌氧含量的相对变化可作为评定运动员有氧代谢能力的敏感指标。     

划船运动员静力及动力性肌肉运动疲劳时肌氧含量的变化特征及对EMG参数的影响

研究目的：1）研究静力和动力性肌肉运动疲劳时肌肉氧含量的变化特点厦其规律；2）了解静力性、动力性递增强度运动时EMG参数变化；3）探讨肌氧含量与EMG参数变化之间的关系，为肌肉疲劳时影响肌电肌氧机制提供可能的理论基础。研究方法：1）肌氧含量的测试：探头纵向旋转让光源和检测器的轴线平行于股外侧肌外侧头大腿测定运动时肌氧含量的变化；2）肌电的测试：采用表面肌电图的测量，得出表面电图各指标参数；3）静力负荷等长收缩：通过力量传感器测出其最大肌肉收缩所对应的MVC；4）动力性负荷运动：采取功率自行车逐级递增负荷的测试方法作为肌肉的动力性运动，同步记录EMG参数，并在每一级负荷朱30S采血测定血乳酸浓度。结论：静力性运动时E／T值大幅度增大的时间大多出现在肌氧停止下降之后，肌氧的降低程度与肌肉疲劳程度有关。动力性运动时血乳酸值随负荷而增加，IEMG的变化趋势与血乳酸相似，IEMG、Oxy-Hb、BI值三者呈非常显著性相关，表明肌肉疲劳时肌肉氧供和内环境的改变也是影响EMG信号的重要因素。     

肌氧含量的近红外无损监测及其在赛艇训练中的应用

利用三波长近红外肌氧无损监测系统,对赛艇运动员在赛艇测功仪上做不同负荷运动时肌氧的变化进行了无损、连续、实时监测,并将受试者测量结果与在运动中血乳酸和心率等参数的变化进行了对比研究。结果表明:随着负荷的改变,肌氧含量的变化较为明显;肌氧的相对变化与运动负荷之间呈现规律性的变化;肌氧浓度与血乳酸浓度具有高度的相关性。     

短期冲刺间歇训练对青年男子篮球运动员肌氧含量和运动能力的影响

观察短期冲刺间歇训练对运动员运动中肌氧含量以及运动能力的影响,为科学合理制定训练计划提供依据。将30名青年男子篮球运动员随机分为实验组(EG,n=15名)和对照组(CG,n=15名)。CG运动员正常训练,EG在正常训练基础上每周进行2次冲刺间歇训练,实验周期为4周。分别于实验前后利用递增负荷实验测定有氧运动能力;30 s Wingate实验测定无氧运动能力;近红外光谱测定技术(NIRS)监测高强度间歇运动实验中(反复5次30 s Wingate实验,间歇期4 min)股外侧肌氧含量的变化。结果显示:实验后,组内与实验前比较,EG受试者递增负荷实验时的最大摄氧量和最大有氧功率升高(P<0.05),1次Wingate实验时的峰值功率和平均功率增加(P<0.05),间歇运动实验中氧合血红蛋白和氧合肌红蛋白、脱氧血红蛋白和脱氧肌红蛋白以及组织氧合指数变化量的绝对值均显著性升高(P<0.05),血红蛋白总量无显著性改变(P>0.05);CG受试者所有指标均无显著性变化(P>0.05)。结果表明:短期冲刺间歇训练改善了青年男子篮球运动员有氧、无氧运动能力以及间歇运动时外周骨骼肌的摄氧能力。     

补醋对力竭运动后血乳酸、血氨、血气等指标的影响

目的探讨递增负荷运动至力竭后补充镇江香醋对消除疲劳及相关生化指标变化的影响.方法研究对象为18名日本国士馆大学体育学院在校优秀的男田径运动员,在不同时间(相隔1周)进行两次递增负荷运动,到力竭后即刻,分别补充蒸馏水和镇江香醋溶液,对两次实验进行自身对照.运动后补充蒸馏水为C组,运动后补镇江香醋稀释溶液为V组.并且测试运动员血乳酸、血氨浓度、血气等指标的变化情况.结果V组与C组在消除血乳酸速率、血液pH值和HCO3-浓度等指标上有显著差异(P＜0.05),清除血氨浓度的变化也存在显著差异(P＜0.05).结论外源性补充镇江香醋溶液可以加快运动后血乳酸的消除速率,提高血液缓冲能力,缓解体内代谢性酸中毒的发生,从而促进运动性疲劳的恢复.     

急性低氧对优秀男子自行车运动员递增负荷运动时肌氧含量的影响

目的:探讨急性低氧环境下递增负荷运动时肌氧含量的变化。方法:通过无损伤近红外光谱学技术(NIRS)监测11名优秀男子自行车运动员常氧和急性低氧下进行递增负荷运动时肌氧含量和心肺系统功能的变化。结果:1)低氧运动时,无氧阈(VT)和最大摄氧量(VO2max)出现时对应的心率、指动脉血氧饱和度(SpO2)、气体代谢和功率均下降,显著低于常氧运动时的值;2)低氧环境下,从开始运动到75%最大功率,Δ[HbO2]降低、Δ[HHb]增高;由75%至100%最大功率时,Δ[HbO2]保持不变,而Δ[HHb]和Δ[THb]增加;在4个不同功率等级下低氧Δ[HbO2]均显著高于常氧值,Δ[HHb]在50%、75%和100%最大功率时均显著低于常氧对应值。结论:1)男子自行车运动员低氧下运动时低氧通气反应高于常氧水平,说明提高自行车运动员在高原训练时的低氧通气反应有利于提高其有氧能力,进而提高运动成绩。2)低氧运动时Δ[HbO2]高于常氧值,Δ[HHb]低于常氧值,提示肌氧含量是反映肌肉疲劳程度的敏感指标。     

女子中长跑运动员肌氧含量与个体乳酸阈关系的探讨

为解决运动训练中生物医学参数的在体、无损、实时监测，利用基于光漫射理论的三波长近红外肌氧监测系统，对受试在功率自行车上做等级性递增负荷运动时局部骨骼肌组织中的肌氧含量的相对变化进行了在体、连续、实时监测与分析，并与血乳酸浓度、运动强度和“个体乳酸阈”等进行对比研究。结果表明：肌氧含量的相对变化与血乳酸浓度、“个体乳酸阈”和运动强度具有密切的关系。为用无损监测肌氧含量的相对变化取代有损监测血乳酸提供了实践依据，为运动员的生理机能评定和运动训练效果的生理学评价引入新的生物学测试技术和方法。     

不同距离游泳对血氨及血乳酸水平的影响及其机制的研究

以专项游泳运动员作为研究对象，探讨游泳运动与血氨、血乳酸的关系、变化规律及其可能机制。研究发现，短时间剧烈运动中血氨水平的变化反映了无氧供能系统的代谢平衡状况。血氨与运动强度关系密切，相对运动强度越大，血氨峰值越高，血氨的肌血弥散速率越快，恢复亦越快。     

女子赛艇运动员两周冬训前后血乳酸和心率的变化研究

血乳酸是评定有氧和无氧代谢能力的重要指标。本文通过观察两周冬训前后女子赛艇运动员血乳酸和心率的变化，评定运动训练对机体有氧、无氧代谢的作用效果，以及探讨递增负荷运动与血乳酸的变化关系。     

大强度的无氧间歇练习、有氧耐力练习及其组合练习的次序对恢复期心脏自主神经功能的影响

目的：评估大强度的无氧间歇练习、有氧耐力练习及其组合练习的次序对恢复期心脏自主神经功能的影响。方法：采用随机交互设计,15名健康男性受试者分别完成4次运动：600 m间歇跑练习、30 min大强度持续跑练习、600 m间歇跑加30 min大强度持续跑练习,30 min大强度持续跑加600 m间歇跑练习,分别在运动前（0~10 min）、整个运动期间和运动后恢复期（0~20 min）记录RR间期,并进行相应HRV分析以及在运动前和运动后即刻进行血乳酸测试。结果：与安静状态相比,运动中HR、EPOC和TRIMP均显著增加,但组合练习次序间不存在显著差异;恢复期20 min内,HR随恢复时间增加逐渐降低,但同一恢复阶段不同运动方案之间无显著差异;RMSSD、SDNN、SDNN/HR、HF和LF变化相似,在整个恢复阶段均显著低于安静值,但HF和LF在恢复期（15~20 min）显著增加;而LF/HF随着恢复时间延长显著增加。结论：大强度的无氧间歇练习、持续有氧练习及其组合练习,在运动后早期恢复阶段（0~20 min）HRV变化趋于一致,提示耐力运动后心脏自主神经功能的调整可能不具有运动形式依赖性。此外,大强度无氧间歇和有氧耐力练习的组合练习次序不影响运动后恢复期心脏自主功能的调节,恢复期20 min内,交感活性仍处于较高水平。     

大鼠运动性疲劳形成和恢复过程ECoG的动态研究

目的:记录并观察大鼠在一次力竭运动过程及恢复期皮层运动区皮层脑电(Electro-corticogram,ECoG)的变化特征,揭示运动性疲劳形成的中枢机制。方法:通过神经电生理学皮层脑电记录方法,记录大鼠在一次性力竭跑台运动过程中及恢复期皮层运动区的ECoG,动态分析运动性疲劳形成和恢复过程中ECoG频率谱、功率谱的变化特征。结果:大鼠在一次性运动疲劳的形成和恢复过程中ECoG特征会发生显著变化,运动状态下ECoG功率谱总功率显著高于安静状态(P<0.05),在6～9Hz频段出现密集的高能量分布;大鼠疲劳状态下运动ECoG功率谱频率分配与非疲劳状态下运动具有显著性差异(P<0.05),表现为δ波比例显著增加,而α波比例显著下降(P<0.05)。力竭即刻频率分配与运动前安静状态差异显著,表现为δ波比例显著增加,θ波比例显著下降(P<0.05),但在30min恢复期后,频率分配恢复至运动前的状态;在力竭运动过程中大鼠ECoG功率谱重心频率逐渐向低频迁移,在力竭前10min显著低于运动前水平(P<0.05),当运动停止后,重心频率即向高频迁移,30min即恢复至运动前水平。结论:运动性中枢疲劳的形成是一个连续累积的过程,大鼠ECoG在运动性疲劳的形成和发展过程均伴随着δ节律比例的显著增加,提示,慢波δ节律可能是运动性疲劳的重要中枢机制之一。同时,运动疲劳所导致的ECoG变化恢复非常迅速,运动停止后短时间内(30min)即能得到有效的恢复。     

Repeated exercise stress impairs volitional but not magnetically evoked electromechanical delay of the knee flexors

The effects of serial episodes of fatigue and recovery on volitional and magnetically evoked neuromuscular performance of the knee flexors were assessed in 20 female soccer players during: (i) an intervention comprising 4 × 35 s maximal static exercise, and (ii) a control condition. Volitional peak force was impaired progressively (-16% vs. baseline: 235.3 ± 54.7 to 198.1 ± 38.5 N) by the fatiguing exercise and recovered to within -97% of baseline values following 6 min of rest. Evoked peak twitch force was diminished subsequent to the fourth episode of exercise (23.3%: 21.4 ± 13.8 vs. 16.4 ± 14.6 N) and remained impaired at this level throughout the recovery. Impairment of volitional electromechanical delay performance following the first episode of exercise (25.5%: 55.3 ± 11.9 vs. 69.5 ± 24.5 ms) contrasted with concurrent improvement (10.0%: 24.5 ± 4.7 vs. 22.1 ± 5.0 ms) in evoked electromechanical delay (P < 0.05), and this increased disparity between evoked and volitional electromechanical delay remained during subsequent periods of intervention and recovery. The fatiguing exercise provoked substantial impairments to volitional strength and volitional electromechanical delay that showed differential patterns of recovery. However, improved evoked electromechanical delay performance might identify a dormant capability for optimal muscle responses during acute stressful exercise and an improved capacity to maintain dynamic joint stability during critical episodes of loading.     

The effects of carbohydrate supplementation during repeated bouts of prolonged exercise on saliva flow rate and immunoglobulin A

The purpose of this study was to assess the effect of carbohydrate (CHO) feeding during different periods of two 90-min cycling bouts (the first bout began at 09:00?h and the second bout began at 13:30 h) at 60% maximal oxygen uptake(VO2max) on saliva flow rate and saliva immunoglobulin A (sIgA) responses to the second exercise bout. The study consisted of three investigations: carbohydrate supplementation during (1) the first hour of the recovery interval (CHO-REC), (2) during the first bout of exercise and (3) during the second bout of exercise. Each investigation included two trials completed in a counterbalanced order and separated by at least 4 days. Participants consumed a lemon-flavoured 10% w/v carbohydrate beverage or placebo (22 ml.kg-1 body mass) in the first hour of the recovery interval (n=8) and 500 ml just before exercise, followed by 250 ml every 20 min during exercise in the first (n=9) and second exercise bouts (n=9). Timed unstimulated saliva samples were collected at 10 min before exercise, after 48-50 min of exercise and during the last 2 min of exercise, at 1 h post exercise, 2 h post exercise (first exercise bout only), and 18 h post exercise (second exercise bout only). Venous blood samples were taken 5 min before exercise and immediately after exercise for both exercise bouts in all trials. The main findings of the present study were as follows. First, carbohydrate ingestion during both exercise bouts, but not during the recovery interval, better maintained plasma glucose concentrations and attenuated the increase in plasma adrenaline and cortisol concentrations after the second exercise bout compared with placebo. Second, carbohydrate feeding had no effect on saliva flow rate and sIgA secretion rate compared with placebo. Third, saliva flow rate and sIgA concentration returned to pre-exercise bout 1 values within 2 h in all trials. Fourth, there was no delayed effect of exercise on oral immunity. These findings suggest that carbohydrate ingestion during the first or second bout of exercise, but not during the recovery interval, is likely to better maintain plasma glucose concentrations and attenuate the responses of plasma stress hormones to a second exercise bout than ingestion of fluid alone. Two bouts of 90 min cycling at 60% VO2max on the same day appears to inhibit saliva flow rate during the second exercise bout but does not alter sIgA transcytosis. Our results show that carbohydrate ingestion during any period of two prolonged exercise bouts does not induce different effects on oral immunity compared with placebo.     

恒定运动和运动后左室舒张功能的变化

采用脉冲多谱勒超声心动图观察恒定运动中和运动后左室舒张功能的变化,研究结果显示100w强度运动时舒张早期最大峰值速度E峰峰值流速、舒张晚期最大峰值速度A峰峰值流速、舒张早期最大瞬时压差PPGE、舒张末期最大瞬时压差PPGA显著大于50w,100w强度运动时E/A值显著小于50w.运动后恢复期E峰、A峰、PPGE、PPGA逐渐减少,E/A值逐渐增大,并很快恢复到安静状态.结论:其动力来源和运动时左室的收缩功能提高有关.     

运动负荷对老年人心肌供血状况的影响及其原因探讨

本实验通过测定老年人在功率自行车上运动时与恢复期间心电图T波、S-T段及R波变化,发现老年人运动时R波无显著改变;T波波幅下降,出现低平、双相及倒置波;S-T段普遍下移;提示老年人运动时心肌轻度缺血。这种缺血状况于运动结束恢复初期逐渐加重,尔后逐渐恢复。     

The effects of carbohydrate supplementation during repeated bouts of prolonged exercise on saliva flow rate and immunoglobulin A

The purpose of this study was to assess the effect of carbohydrate (CHO) feeding during different periods of two 90-min cycling bouts (the first bout began at 09:00?h and the second bout began at 13:30?h) at 60% maximal oxygen uptake ([Vdot]O_2max) on saliva flow rate and saliva immunoglobulin A (sIgA) responses to the second exercise bout. The study consisted of three investigations: carbohydrate supplementation during (1) the first hour of the recovery interval (CHO-REC), (2) during the first bout of exercise and (3) during the second bout of exercise. Each investigation included two trials completed in a counterbalanced order and separated by at least 4 days. Participants consumed a lemon-flavoured 10% w/v carbohydrate beverage or placebo (22?ml?·?kg^?1 body mass) in the first hour of the recovery interval (n = 8) and 500?ml just before exercise, followed by 250?ml every 20?min during exercise in the first (n = 9) and second exercise bouts (n = 9). Timed unstimulated saliva samples were collected at 10?min before exercise, after 48?–?50?min of exercise and during the last 2?min of exercise, at 1?h post exercise, 2?h post exercise (first exercise bout only), and 18?h post exercise (second exercise bout only). Venous blood samples were taken 5?min before exercise and immediately after exercise for both exercise bouts in all trials. The main findings of the present study were as follows. First, carbohydrate ingestion during both exercise bouts, but not during the recovery interval, better maintained plasma glucose concentrations and attenuated the increase in plasma adrenaline and cortisol concentrations after the second exercise bout compared with placebo. Second, carbohydrate feeding had no effect on saliva flow rate and sIgA secretion rate compared with placebo. Third, saliva flow rate and sIgA concentration returned to pre-exercise bout 1 values within 2?h in all trials. Fourth, there was no delayed effect of exercise on oral immunity. These findings suggest that carbohydrate ingestion during the first or second bout of exercise, but not during the recovery interval, is likely to better maintain plasma glucose concentrations and attenuate the responses of plasma stress hormones to a second exercise bout than ingestion of fluid alone. Two bouts of 90?min cycling at 60% [Vdot]O_2max on the same day appears to inhibit saliva flow rate during the second exercise bout but does not alter sIgA transcytosis. Our results show that carbohydrate ingestion during any period of two prolonged exercise bouts does not induce different effects on oral immunity compared with placebo.     

Acute intraocular pressure changes during isometric exercise and recovery: The influence of exercise type and intensity,and participant´s sex

ABSTRACT

We assessed the intraocular pressure (IOP) behaviour during a 1-minute period of isometric physical effort and the immediate 1-minute of recovery in the mid-thigh clean pull and squat exercises at three different intensities. Twenty physically active individuals performed the isometric mid-thigh clean pull and squat exercises at three intensities (0% [low-intensity], 25% [medium-intensity] and 50% [high-intensity] of the maximum isometric force). IOP was semi-continuously measured by rebound tonometry. There was a statistically significant effect of exercise intensity on IOP (p < 0.001, ?_p² = 0.416), observing that IOP increments were positively associated with exercise intensity. The mid-thigh clean pull and squat exercises did not demonstrate differences (p = 0.510), and also, no differences were observed between men and women (p = 0.683). The IOP changes during the isometric physical effort showed a positive linear behaviour in all conditions (r = 0.70 to 0.96). IOP returned to baseline levels after 8 seconds of recovery. Our data showed a progressive and instantaneous IOP increment during isometric exercise, which was positively associated with exercise intensity. IOP changes were independent on the type of exercise and participant´s sex. After exercise, IOP rapidly (≈ 8 seconds) returned to baseline levels.     

A new approach to quantifying physical demand in rugby union

Abstract

The objective of the study was to describe an original approach to assessing individual workload during international rugby union competitions. The difference between positional groups and between the two halves was explored. Sixty-seven files from 30 French international rugby union players were assessed on a computerised player-tracking system (Amisco Pro^®, Sport Universal Process, Nice, France) during five international games. Each player’s action was split up into exercise and recovery periods according to his individual velocity threshold. Exercise-to-recovery (E:R) period ratios and acceleration were calculated. Results indicated that about 65% of exercise periods lasted less than 4 s; half of the E:Rs were less than 1:4, and about one-third ranged between 1 and 1:4 and about 40% of exercise periods were classified as medium intensity. Most acceleration values were less than 3 m·s^?2 and started from standing or walking activity. Back row players showed the highest mean acceleration values over the game (P < 0.05). No significant decrease in physical performance was seen between the first and second halves of the games except for back rows, who showed a significant decrease in mean acceleration (P < 0.05). The analysis of results emphasised the specific activity of back rows and tended to suggest that the players’ combinations of action and recovery times were optimal for preventing large decrease in the physical performance.     

A pilot study on quantification of training load: The use of HRV in training practice

Recent laboratory studies have suggested that heart rate variability (HRV) may be an appropriate criterion for training load (TL) quantification. The aim of this study was to validate a novel HRV index that may be used to assess TL in field conditions. Eleven well-trained long-distance male runners performed four exercises of different duration and intensity. TL was evaluated using Foster and Banister methods. In addition, HRV measurements were performed 5 minutes before exercise and 5 and 30 minutes after exercise. We calculated HRV index (TL_HRV) based on the ratio between HRV decrease during exercise and HRV increase during recovery. HRV decrease during exercise was strongly correlated with exercise intensity (R = ?0.70; p < 0.01) but not with exercise duration or training volume. TL_HRV index was correlated with Foster (R = 0.61; p = 0.01) and Banister (R = 0.57; p = 0.01) methods. This study confirms that HRV changes during exercise and recovery phase are affected by both intensity and physiological impact of the exercise. Since the TL_HRV formula takes into account the disturbance and the return to homeostatic balance induced by exercise, this new method provides an objective and rational TL index. However, some simplification of the protocol measurement could be envisaged for field use.