补充谷氨酰胺对递增负荷训练游泳运动员血液谷氨酰胺水平的影响

目的:探讨补充谷氨酰胺(Gln)对递增负荷训练游泳运动员血液谷氨酰胺水平的影响及其作用机制。方法:广东省游泳运动员12名,随机分为实验组(T,补充Gln,n=5)及对照组(C,n=7),进行为期2个月的递增强度负荷训练。实验前1天上午,运动员空腹采集肘静脉血,分别测定血浆Gln、Hb、血清CK及皮质醇(Cortisol);实验第29天(T组服用Gln第1天)晨,运动员空腹进行第2次血样采集与分析;即日起,T组2次大运动量训练结束后立即补充Gln(0.15g/kgbodymass),持续服用28天。分别于实验第36天(T组服用Gln第7天)和实验第57天(T组服用Gln第28天),对T、C组运动员进行血样分析。结果:所有运动员正常训练4周后,血浆Gln水平显著升高(P<0.01)。实验组服用Gln第28天,血浆Gln浓度显著高于服用Gln第7天(1317.64±401.445μmmol/Lvs.954.88±317.87μmmol/LP<0.05)。对照组训练5周后较训练4周时血浆Gln水平无显著性变化(1280.46±441.73μmmol/Lvs.1251.37±292.06μmmol/L,P>0.05),实验8周后,血浆Gln水平较5周时显著下降(1280.46±441.73μmmol/Lvs.891.64±322.37μmmol/L,P<0.05)。T组服用Gln7天后,皮质醇水平显著升高(P<0.01)。补充Gln后,T组Hb水平显著上升,CK水平显著下降,C组Hb、CK未见明显变化。结果表明,血浆Gln水平会随训练产生适应性变化,补充外源性Gln可以在一定程度上削弱由训练引起的血浆Gln水平下降的程度。     

红光照射对优秀女子篮球运动员训练恢复效果的实验研究

目的:观察红光全身照射后优秀女子篮球运动员疲劳相关指标变化,探寻运动训练恢复有效方法与途径。方法:选择中国女子篮球甲级联赛(WCBA)2007～2008年度冠军队八一女篮20名运动员为研究对象,分为实验组(10人)和对照组(10人),两组均按照既定训练计划进行为期14天的正常训练,实验组每天晚上使用红光治疗仪进行全身红光照射30min。实验前后运动员进行睡眠质量指数量表(PSQI)、有氧能力、免疫指标测试,在第14天大负荷训练课中、后即刻或次日晨进行机体反应指标心率、RPE、CK、BUN、血象、睾酮(T)、皮质醇(C)等测试。结果:实验组PSQI显著低于对照组(P<0.01),实验组和对照组血红蛋白、大运动负荷机体反应、有氧能力、免疫指标均未见组间或实验前后具有显著性差异(P>0.05)。结论:为期14天、每天30min红光全身照射有助于优秀女子篮球运动员改善训练后的睡眠质量。     

高住高练低训对优秀女子跆拳道运动员红细胞膜及有氧能力的影响

目的:探讨高住高练低训(HiHiLo)对运动员红细胞膜和有氧能力的影响。方法:13名女子跆拳道运动员分为实验组(8名)和对照组(5名),进行4周实验。实验组每晚在低氧房(氧浓度14.7%,模拟海拔2800m高原环境)居住10小时,每周在低氧房进行3次72%最大摄氧量蹬功率自行车练习,每次30分钟;对照组平原居住,每周在平原环境进行3次80%最大摄氧量蹬功率自行车练习,每次30分钟。两组平时的专项训练由同一教练、按同一训练计划、于同一道馆进行。分别于实验前、入住10小时、实验1周、2周、3周、4周测试两组受试者血液红细胞变形指数、红细胞膜流动性、膜band-3蛋白含量以及个体无氧阈(ILT)。结果:实验组在实验3周时band-3蛋白含量显著高于实验前(P<0.05);4周时,实验组band-3蛋白含量显著高于实验前(P<0.01)和对照组(P<0.05);实验组4周时的ILT显著高于实验前(P<0.05)和对照组(P<0.01)。结论:HiHiLo可提高红细胞膜band-3蛋白含量,有利于红细胞发挥正常生理功能;HiHiLo可提高机体有氧运动能力。     

中药生脉饮对女子散打运动员夏训期体能与免疫功能的影响

目的:探讨夏训期服用中药生脉饮对女子散打运动员体能与免疫功能的调节机制。方法:14名女子散打运动员随机分为实验组和对照组,两组训练内容相同,实验组饮用含中药生脉饮40ml+酸梅汁160 ml的饮料,对照组只饮用酸梅汁饮料200 ml,每日上下午训练结束时各1次,持续4周。4周实验前后分别进行相关测试,包括体能测试、血常规、生化及免疫指标,采用日常训练状态监控测量表和RPE主观感觉疲劳程度评定量表进行日常机能监控。结果:饮用生脉饮4周后,实验组最大摄氧量、全力击打沙袋运动后7 min血乳酸值、IgG和IgM较实验前均有显著性差异(P<0.05);实验组和对照组肌酸激酶和血清睾酮实验前后差值比较有显著性差异(P<0.05)。日常训练状态监控测量表和RPE主观感觉疲劳程度评定量表数据显示两组运动员均未出现过度疲劳。结论:夏季饮用生脉饮对女子散打运动员有氧能力有一定的促进作用,对疲劳恢复有一定的调节作用;能提高运动员免疫球蛋白含量,一定程度上增强了机体的免疫力。     

不同月经周期赛艇和短跑运动员性激素水平和运动能力的观察

通过测定浙江省13名女子赛艇运动员和12名女子短跑运动员卵泡期和黄体期的性激素水平、运动成绩及完成定量负荷运动后的血乳酸水平,观察不同项目女运动员不同月经周期激素水平和运动成绩的变化,以探讨不同月经周期与运动能力的关系。研究结果显示:女子赛艇和短跑运动员黄体期的孕酮(P)和睾酮(T)水平显著高于卵泡期(P<0.05);赛艇运动员黄体期促卵泡激素(FSH)水平显著高于卵泡期(P<0.05),而运动员黄体期和卵泡期的雌二醇(E2)和促黄体生成素(LH)水平则无显著性差异。赛艇运动员黄体期500m测功仪成绩显著优于卵泡期(P<0.01),而2000m测功仪成绩两期无显著性差异;短跑运动员黄体期100m、200m成绩均显著优于卵泡期(P<0.05,P<0.01)。定量负荷运动后,赛艇和短跑运动员黄体期的血乳酸水平均显著低于卵泡期(P<0.05,P<0.01)。结果表明,受试运动员黄体期机能状态较好,这可能与不同月经周期中激素水平变化以及在运动状态下各种激素间的协同效应有关。提示对女运动员的生理周期应给予充分重视。     

补充复合抗氧化剂对中长跑运动员身体机能的影响

目的 :观察运用复合抗氧化剂对耐力项目运动员促进体能恢复的作用。方法 :15名男性省级中长跑运动员随机分为对照组和实验组 ,进行为期 3周的大强度训练 ,实验组每天早晚各补充 10ml复合抗氧化剂“升态口服液” ,对照组服用安慰剂。分别测试受试对象实验前、后的乳酸无氧阈功率、心率恢复和血液生化指标。结果 :服用“升态口服液”后实验组的乳酸无氧阈功率明显提高 (P <0 0 1) ,而对照组则无显著变化。服用口服液 2周和 3周后实验组血清BUN水平明显低于对照组 (P <0 0 5 ) ;两组间及其组内不同时间的血清T水平无显著变化。对照组的CK活性实验后比实验前明显升高 (P <0 0 5 ) ;而实验组则无明显差异。实验组的LDH活性实验后明显低于实验前 (P <0 0 5 ) ,血清MDA浓度实验后明显低于实验前 (P <0 0 5 ) ,同时显著低于对照组 (P <0 0 5 )。对照组的血清SOD水平 ,实验后明显低于实验前 (P <0 0 5 ) ,而实验组无明显变化。提示服用“升态口服液”可降低运动后血清CK水平 ,促进中长跑运动员有氧能力提高 ,有效清除运动中产生的自由基 ,具有一定的抗疲劳作用。     

高住低训对优秀女子跆拳道运动员运动能力和血象的影响

目的:探讨高住低训对女子跆拳道运动员运动能力和血象的影响。方法:13名优秀女子跆拳道运动员随机分为实验组(高住低训,n=8)和对照组(n=5),分别在模拟海拔2500m低氧舱(氧浓度15.4%左右)内和平原环境下进行为期4周的高住低训和跆拳道常规专项训练。分别于实验前、高住低训第28天和高住低训结束后10天进行有氧运动能力和无氧运动能力测试,并于实验前1天、高住低训期间每周及高住低训结束后第3、12天清晨空腹取血进行血细胞分析。结果:(1)实验组高住低训第28天和高住低训结束后10天VO2max和PWC170均显著高于实验前(P<0.01),4000m成绩显著优于实验前(P<0.01)。对照组变化不明显。(2)实验组高住低训结束后10天Wingate最高功率显著高于对照组(P<0.05)。实验组高住低训第28天和高住低训结束后10天Wingate平均功率均显著高于自身实验前(P<0.05和P<0.01),Wingate疲劳指数则分别显著低于自身实验前(P<0.05和P<0.01)。对照组无明显变化。(3)实验组高住低训第28天血红蛋白、红细胞数目、红细胞压积显著高于自身实验前(P<0.05),实验组在高住低训第25天和28天血红蛋白水平分别显著高于对照组(P<0.05和P<0.01)。结果表明,为期28天的模拟海拔2500m高度的高住低训能提高女子跆拳道运动员有氧运动能力,同时在一定程度上提高其无氧功和60秒踢靶成绩。另外,高住低训可以提高与跆拳道运动员机体载氧能力直接相关的血液指标水平,这种改变主要表现在实验第3、4周。     

采用递增负荷跑台运动探讨丙酮酸透膜与乳酸穿梭关系的研究

目的:探讨丙酮酸透膜与乳酸穿梭的关系。方法:不同运动能力的20名男性大学生分为运动组和对照组,每组10人,连续进行不同最大摄氧量百分比递增强度跑台运动,每级负荷运动3分钟,3分钟末取血,测试受试者血乳酸和丙酮酸浓度。结果:(1)运动组乳酸阈平均值出现在75%最大摄氧量强度,对照组出现在65%最大摄氧量强度,两组各级负荷血乳酸值与上一级负荷比较均有显著或非常显著性差异(P<0.05,P<0.01,P<0.001)。(2)对照组各级负荷下血丙酮酸浓度与上一级负荷比较均无显著性差异(P>0.05),运动组在75%、95%最大摄氧量强度下的血丙酮酸浓度与上一级负荷比较有显著性差异(P<0.05,P<0.01)。结果表明:(1)丙酮酸在乳酸阈之前不能或不易透过肌细胞膜。(2)提示丙酮酸透膜与运动强度、时相有关,其机制可能与乳酸穿梭到一定程度有关。     

高住高练低训对足球运动员红细胞CD58、CD59和T淋巴细胞CD2表达的影响

目的:探讨高住高练低训(HiHiLo)对红细胞调节T淋巴细胞免疫能力的影响机制。方法:以16名北京体育大学足球专项运动员为对象,实验组(HiHiLo组)和对照组(低住低训组,LoLo组)各8名。实验组每晚入住低氧房(O2浓度14.2%,相当于海拔3000米高度)10小时,每周在低氧房内进行2次72%最大摄氧量蹬功率自行车30分钟训练;对照组平原居住,每周进行2次平原80%最大摄氧量蹬功率自行车30分钟训练。两组每周进行3次由同一教练执教的专项训练。实验期4周。分别于实验前、入住10小时后、实验2、3、4周末清晨取静脉血,与相应的荧光标记抗体反应,采用流式细胞仪记录红细胞CD58、CD59平均荧光强度及T淋巴细胞CD2阳性细胞率。结果:4周实验后,实验组和对照组CD58表达分别较实验前下降了33.14%和30.29%(均P<0.01),两组间有显著性差异(P<0.05);CD59表达分别下降了10.38%和9.68%(均P<0.01),两组间无显著性差异(P>0.05);T淋巴细胞CD2阳性率在实验期无明显变化,两组间也未见显著性差异(P>0.05)。结果表明,HiHiLo和LoLo均可影响人体红细胞CD58、CD59表达,但HiHiLo的影响作用有更明显的趋势,而T淋巴细胞CD2表达受低氧和/或训练刺激的影响不明显。     

低氧预适应结合长时间亚高原训练前后男子赛艇运动员身体机能分析

目的:分析低氧预适应结合亚高原训练前后男子赛艇运动员身体机能状态的变化.方法:16名优秀男子赛艇运动员为对象,先进行10天HiLo低氧训练,模拟海拔高度为1200～1500 m.再于海拔1500 m进行8周亚高原训练.分别于低氧训练前和亚高原训练前、中、后不同时段测定分析运动员身体机能状态,测试指标包括:氧转运系统指标(Hb、RBC)、内分泌系统指标(T、C、T/C、EPO)、免疫系统指标(WBC、IgA、IgM、IgG)以及CK和BU.结果:与低氧训练前相比,1)EPO在低氧训练后和高原训练第3天出现两个峰值,升高幅度分别为26.27％和26.60％(P＜0.01).Hb在低氧后显著下降(P＜0.01),高原训练第3天,第1、3、7周,下高原后第2、3周显著升高(P＜0.05或P＜0.01);2)白细胞在实验期间升高(P＜0.01),IgA和IgG无显著变化(P＞0.05),IgM在低氧训练后、高原训练第3周、下高原后第2周(P＜0.01,P＜0.05,P＜0.05)显著升高;3)低氧训练后血清睾酮下降(P＞0.05),高原训练第3天显著升高(P＜0.05),血清皮质醇在高原训练第3周(P＜0.01)、第5周(P＜0.05)显著下降,T/C在高原训练第3天和第3、5周显著升高(P＜0.05).结论:低氧预适应干预加快了运动员高原适应;10天低氧预适应结合8周亚高原训练对运动员机能状态产生良好影响,运动员未出现过度疲劳,血液载氧能力提高,免疫能力未见大幅下降.     

Increased training intensity effects on plasma lactate, ventilatory threshold, and endurance

The purpose of this study was to determine the effects of increased training intensity (ITI) on VO2max, plasma lactate accumulation, ventilatory threshold (VT), and performance in trained distance runners. Seven trained male distance runners increased their training intensity three d.wk-1 at 90-95% HRmax for eight wk. ITI did not alter VO2max (65.3 +/- 2.3 vs 65.8 +/- 2.4 ml.kg-1.min-1) but improved 10 km race time (means = 63 s decrease) and increased run time to exhaustion on the treadmill at the same speed and grade (means = 3.88 min). Significant decreases in plasma lactate concentration at 85 and 90% of VO2max were observed after ITI. No differences were found in plasma lactate at 65, 70, 75 or 80% of VO2max or VT following ITI. Significant correlations were obtained between 10 km race times and changes in plasma lactate at 85 and 90% of VO2max (r = 0.69 and 0.73, respectively). Lactate accumulation at both 2.5 and 4.0 mM were at a significantly greater percent of VO2max after ITI. Additionally, the changes in plasma lactate were dissociated from alterations in VT after ITI. These data indicate that previously trained runners can increase training intensity to improve endurance performance by lowering lactate at the intensity at which they trained despite no changes in VO2max and VT.     

Physiologic changes in rowing performance associated with training in collegiate women rowers

To evaluate the physiologic changes in rowing performance during the training season, selected cardiorespiratory variables were measured three times at 3-month intervals in seven collegiate women rowers during incremental exercise on the rowing ergometer. Values for maximal oxygen consumption (VO2 max) and peak power production increased by 14% and 18%, respectively, over the 6-month period. Maximal heart rate was unchanged with training. Oxygen-pulse increased significantly (+ 14%) during the training season, while the ventilatory equivalent for oxygen did not change. Oxygen consumption as a percent of VO2 max and heart rate at the anaerobic threshold (AT) decreased during the first 3 months of predominantly aerobic training, but increased significantly in the last 3 months with greater anaerobic conditioning. The changes demonstrated by physiologic testing corresponded to the particular type of training emphasized during the 6-month period. Serial measurements of VO2 max and AT can be used to assess the benefits of specific training. Based on these results, individual guidelines for aerobic and anaerobic conditioning can be developed using the heart rate response at the AT.     

Effect of training on anaerobic threshold, maximal aerobic power and anaerobic performance of preadolescent boys

To evaluate the effect of a 9-week interval training program on aerobic capacity, anaerobic capacity, and indices of anaerobic threshold of preadolescent boys, 28 10.2- to 11.6-year-old boys were tested. The test included laboratory evaluation of anaerobic capacity (Wingate anaerobic test) and evaluation of VO2 max and anaerobic threshold indices from a graded exercise test and measurement of blood lactate. The tests also included a 1200-m run to investigate the relationship of laboratory fitness indices, VO2 max, anaerobic threshold indices, and indices of anaerobic capacity to the performance of the run. It was found that in 10- to 11-year-old boys, a 9-week interval training increased the indices of anaerobic capacity: mean power by 10% and peak power by 14%. No change was found in percent fatigue. The training also increased VO2 max by 7% in absolute terms and by 8%/kg body weight. A significant increase was also found in the running velocity at the anaerobic threshold (running velocity at inflection point of lactate accumulation curve), but in relative terms (percent of VO2 max), the anaerobic threshold decreased by approximately 4.4%. It is concluded that proper training may improve maximal aerobic power and anaerobic capacity of preadolescent boys. It is also concluded that anaerobic threshold measures are less sensitive to the training regimen than VO2 max and that the 1200-m running performance is strongly associated with both aerobic and anaerobic capacities and less with the anaerobic threshold, which in preadolescent boys seems to be higher than in adults.     

The effect of inspiratory and expiratory respiratory muscle training in rowers

This study examined inspiratory and expiratory resistive loading combined with strength and endurance training on pulmonary function and rowing performance. Twenty-one male (n = 9) and female (n = 12) rowers were matched on 2000 m simulated rowing race time and gender and randomly assigned to two groups. The experimental group trained respiratory muscles using a device that provided both an inspiratory and expiratory resistance while the control group used a SHAM device. Respiratory muscle training (RMT) or SHAM was performed 6 d/wk concurrent with strength (3 d/wk) and endurance (3 d/wk) training on alternate days for 10 weeks. Respiratory muscle training (RMT) enhanced maximum inspiratory (PI(max)) and expiratory (PE(max)) strength at rest and during recovery from exercise (P < 0.05). Both groups showed improvements in peak VO2, strength, and 2000 m performance time (P < 0.05). It was concluded that RMT is effective for improving respiratory strength but did not facilitate greater improvements to simulated 2000 m rowing performance.     

Exercise training below and above the lactate threshold in the elderly

In this study we report the effects of training at intensities below and above the lactate threshold on parameters of aerobic function in elderly subjects (age range 65-75 yr). The subjects were randomized into high-intensity (HI, N = 8; 75% of heart rate reserve = approximately 82% VO2max = approximately 121% of lactate threshold) and low-intensity (LI, N = 9; 35% of heart rate reserve = approximately 53% VO2max = approximately 72% of lactate threshold) training groups which trained 4 d.wk-1 for 30 min.session-1 for 8 wk. Before and after the training, subjects performed an incremental exercise test for determination of maximal aerobic power (VO2max) and lactate threshold (LT). In addition, the subjects performed a 6-min single-stage exercise test at greater than 75% of pre-training VO2max (SST-High) during which cardiorespiratory responses were evaluated each minute of the test. After training, the improvements in VO2max (7%) for LI and HI were not different from one another (delta VO2max for LI = 1.8 +/- 0.7 ml.kg-1.min-1; delta VO2max for HI = 1.8 +/- 1.0 ml.kg-1.min-1) but were significantly greater (P = 0.02) than the post-testing change observed in the control group (N = 8). Training improved the LT significantly (10-12%; P less than 0.01) and equally for both LI and HI (delta LT for for LI = 2.3 +/- 0.6 ml O2.kg-1.min-1; delta LT for HI = 1.8 +/- 0.8 ml O2.kg-1.min-1).(ABSTRACT TRUNCATED AT 250 WORDS)     

Distinctive effects of three different modes of exercise on oxygen uptake, heart rate and blood lactate and pyruvate.

We intended to investigate the effects of different modes of exercise on oxygen uptake (VO2), the heart rate and the levels of lactate and pyruvate in venous blood. For this, untrained male subjects performed three modes of exercise with a treadmill (TR), a bicycle ergometer (UP) and a supine leg ergometer (SU). The percentage of maximal oxygen uptake (% VO2max) and VO2/weight for TR were significantly higher than those for UP or SU at lactate levels of 2, 3 and 4 mmol/l. The heart rate was also higher for TR than for SU at these lactate levels. The correlations of blood lactate with % VO2max, VO2/weight and the heart rate were significant for TR and SU, but not for UP. Blood lactate levels were lower for TR than for SU or UP at 60, 70, 80% VO2max, whereas the values for UP were lower than those for SU only at 60% VO2max. Blood pyruvate levels were always lower for TR than for SU. The ratios of lactate/pyruvate differed for TR and SU only at 60% VO2max. For a given mode of exercise, blood lactate and the ratio of lactate/pyruvate increased with an increase in % VO2max, but those of pyruvate did not. These results reveal that the relationships between any two of lactate, pyruvate, VO2 and the heart rate are different at different modes of exercise, and that blood lactate depends on adaptation of muscles to a mode of exercise rather than on the quantity of muscles mobilized.     

Responses to training in cross-country skiers.

PURPOSE: This study evaluated whether cross-country skiers who did not respond positively to a training program consisting of high volume and low intensity would improve if high-intensity training volume was doubled during a subsequent training year. METHODS: During the first year of the study, cross-country skiers (N = 14) were evaluated for VO2max, VO2threshold, lactate response, max arm power, and competitive results after a standard training program. During the second year, the athletes were divided into a control group (athletes who had responded well to the training) and a treatment group (athletes who had responded poorly to the training). The control group (N = 7) repeated the previous year's training program. The treatment group (N = 7) was given a modified training program which increased high-intensity training time as a percentage of total training from < 17% to > 35% and decreased low-intensity training volume 22%. RESULTS: The treatment group, using the high-intensity training program, demonstrated significantly improved VO2max, VO2threshold, max arm power, and competitive results (P < 0.05). CONCLUSIONS: Increased volume of high-intensity training may improve competitive results in cross-country skiers who fail to respond to increased volume of low-intensity training.     

Ventilatory responses and entrainment of breathing during rowing

The purpose of this investigation was to investigate the hypothesis that respiration was coupled with the mechanics of the rowing stroke. In the first part of the study, physiologic responses during incremental exercise on the variable-resistance rowing ergometer were compared in 16 untrained female subjects (U), 17 collegiate female rowers (C), and 21 elite oarswomen (E). Minute ventilation (VE) and frequency of respiration (fR) were examined on a log scale as their relationship with oxygen consumption (VO2) was exponential. The slopes for log VE/VO2 were similar for collegiate (0.65 +/- 0.02) and elite (0.59 +/- 0.01) rowers, but the slope was significantly higher for the untrained (0.87 +/- 0.01) subjects (P less than 0.001). Elite rowers utilized a higher tidal volume (VT) response per VO2 (0.68 +/- 0.04 vs 0.30 +/- 0.05; P = 0.01) and lower log fR response per VO2 (0.27 +/- 0.02 vs 0.50 +/- 0.03; P = 0.01) compared with collegiate rowers. The ratio of fR/strokes per minute (SPM) averaged 1.5 in E athletes but varied in the U and C groups. In the second part of the study, pattern and timing of respiration were recording using an inspiratory pneumotachygraph, analyzed, and compared with specific phases of the rowing stroke in ten untrained subjects and nine elite rowers. The ratio of inspiratory time (T1)/total respiratory time (TTOT) decreased during the drive phase and increased during the recovery phase in both untrained subjects and elite rowers.(ABSTRACT TRUNCATED AT 250 WORDS)     

Inspiratory muscle training fails to improve endurance capacity in athletes

PURPOSE: The purpose of this study was to examine the effects of specific inspiratory muscle training (IMT) on respiratory muscle strength and endurance and whole-body endurance exercise capacity in competitive endurance athletes. METHODS: Seven collegiate distance runners (5 male/2 female; VO2max = 59.9 +/- 11.7 mL.kg-1.min-1) were recruited to participate in this study. Initial testing included maximal oxygen consumption (VO2max), sustained maximal inspiratory mouth pressure (MIP), breathing endurance time (BET) at 60% MIP, and endurance run time (ERT) at 85% VO2max. Heart rate (HR), minute ventilation (VE), oxygen consumption (VO2), and ratings of perceived dyspnea (RPD) were recorded at 5-min intervals and during the last minute of the endurance run. Blood lactate concentration (BLC) was also obtained immediately before and at 2 min after the endurance run. All testing was repeated after 4 wk of IMT (50-65% MIP, approximately 25 min x d(-1), 4-5 sessions/week, 4 wk). RESULTS: After 4 wk of IMT, MIP and BET were significantly increased compared with pretraining values (P < 0.05). No significant differences between pre and post values were observed in VO2max or ERT at 85% VO2max after IMT. No significant differences between pre and post values were detected in HR, VE, VO2, or RPD during the endurance run as measured at steady state and end of the test after IMT. BLC was not significantly different before or at 2 min after the endurance run between pre and post IMT. CONCLUSION: These results suggest that IMT significantly improves respiratory muscle strength and endurance. However, these improvements in respiratory muscle function are not transferable to VO2max or endurance exercise capacity as assessed at 85% VO2max in competitive athletes.     

The ventilatory anaerobic threshold is related to, but is lower than, the critical power, but does not explain exercise tolerance at this workrate

AIM: The aim of the present study was to investigate the relationships between critical power (CP), maximal aerobic power and the anaerobic threshold and whether exercise time to exhaustion and work at the CP can be used as an index in the determination of endurance. METHODS: An incremental maximal cycle exercise test was performed on 30 untrained males aged 18-22 years. Lactate analysis was carried out on capillary blood samples at every 2 minutes. From gas exchange parameters and heart rate and lactate values, ventilatory anaerobic thresholds, heart rate deflection point and the onset of blood lactate accumulation were calculated. CP was determined with linear work-time method using 3 loads. The subjects exercised until they could no longer maintain a cadence above 24 rpm at their CP and exercise time to exhaustion was determined. RESULTS: CP was lower than the power output corresponding to VO2max, higher than the power outputs corresponding to anaerobic threshold. CP was correlated with VO2max and anaerobic threshold. Exercise time to exhaustion and work at CP were not correlated with VO2max and anaerobic threshold. CONCLUSIONS: Because of the correlations of the CP with VO2max and anaerobic threshold and no correlation of exercise time to exhaustion and work at the CP with these parameters, we conclude that exercise time to exhaustion and work at the CP cannot be used as an index in the determination of endurance.