Kir6.2基因E23K位点多态性与耐力训练后血糖、胰岛素和VO2max改变的关系

目的探讨Kir6.2基因E23K位点多态性与耐力训练所致的血糖、胰岛素和VO2max改变间的关系.方法采用PCR-RFLP技术对214例美国各种族50至75岁男女受试者的Kir6.2位点E23K多态性进行基因型分析.受试者在专人监控下进行24周的耐力训练后,观察其E23K与血糖、胰岛素和VO2max之间的关系.结果(1)三种基因型受试者的空腹血糖、胰岛素和VO2max的基础值无显著差异;(2)24周耐力训练后,三种基因型受试者的VO2max均显著升高(P＜0.05),体重和体脂则显著下降(P＜0.05),身高体重指数(BMI)和呼吸商(RER)则在男性各基因型中显著下降(P＜0.05);(3)24周耐力训练后,三种基因型受试者的空腹胰岛素水平和曲线下面积(AUC)均显著下降(P＜0.05),但训练并未引起空腹血糖及其AUC显著变化.(4)男性EK基因型RER显著低于EE和KK基因型,女性则表现为KK基因型显著高于EE基因型.结论(1)无论E23K位点的基因型为EE、EK或KK,24周的耐力训练均可提高受试者的VO2max并降低体重、体脂、空腹胰岛素水平和AUC;(2)耐力训练对男性BMI和RER降低的影响更显著;(3)E23K多态性与RER的关系较VO2max和血糖水平更密切.     

PPARδ基因多态与有氧能力及训练敏感性的关联研究

目的探讨过氧化物酶体增殖物激活受体δ(PPARδ)基因第四外显子的单核苷酸多态(C294T)是否与有氧运动能力及训练敏感性相关联。方法对102名中国北方地区汉族男性青年进行为期18周的耐力训练(每次5000米、每周3次)。强度以个体通气无氧阈(VT)对应的心率(HRVT)为标准,前10周采用95%通气无氧阈对应的心率(HRVT±3),后8周采用105%通气无氧阈对应的心率(HRVT±3)。递增负荷运动实验测定受试者训练前后VO2max及相关指标和跑节省化时的心率(HR)、通气量(VE)和摄氧量(VO2)。采用限制性片断长度多态(PCR-RFLP)法测定PPARδ基因C294T位点。结果三种基因型的分布频率分别为CC基因型9人(0.09)、CT基因型37人(0.36)和TT基因型56人(0.55),符合Hardy-Weinberg平衡。按基因型分组后,CC基因型训练前的VO2max相对值显著性高于CT基因型和TT基因型(P<0.05);携带不同基因型群体的VO2max、跑节省化测试中的各项指标的变化率无显著性差异(P>0.05)。结论PPARδ基因第四外显子的单核苷酸C294T多态与VO2max相对值的初始值相关联,但与有氧耐力训练效果不关联。     

大学生最大吸氧量平台持续时间及其与耐力运动成绩关系的初步研究

通过对普通大学生VO2 maxPD(最大吸氧量平台持续时间 )水平、极量和亚极量状态下耐力运动能力进行测试与分析 ,初步将VO2 maxPD应用于大学生有氧能力评定 ,为进一步完善大学生有氧能力的评定提供实验依据。结果表明 :普通大学生存在最大VO2 maxPD ,男生VO2 maxPD明显低于女生 ;与VO2 max相比 ,VO2 maxPD和AT能更全面地评价人体的有氧运动能力 ,VO2 maxPD与VO2 max和AT均无相关关系 ,可能是从另一方面反映有氧能力的重要指标之一     

肌红蛋白基因多态与有氧训练效果的关联性分析

目的:探讨肌红蛋白第2外显子的单核苷酸多态(A79G)与有氧耐力训练效果的关联性。方法:对中国北方新征入伍的104名汉族士兵进行每次5000米、每周3次、训练强度为95～105%通气无氧阈(VT)、为期20周的耐力训练。递增负荷运动实验测定受试对象训练前后最大摄氧量(VO2max)和通气无氧阈(VT),PCR-RFLP法测定基因多态性,分析基因多态性与训练效果之间的关联性。结果:3种基因型的分布频率分别为AA(0.52)、AG(0.45)、GG(0.03),分布频率符合Hardy-weinberg遗传平衡定律;训练后3种基因型VO2max的组间比较均无显著性差异(P>0.05);训练后GG组和AG组VT显著提高(P<0.05),AA组达到VT时仅HR显著升高,其余指标均无显著变化(P>0.05)。在VO2max和VT的变化率(Δ%)方面,GG组受试者提高最多,AG组居中,AA组提高最少。提示肌红蛋白基因第2外显子的单核苷酸多态(A79G)与有氧耐力训练效果有一定关联,79G等位基因携带者对有氧耐力训练可能更敏感。     

采用100%vVO_2max恒定负荷运动测定VO_2max可行性分析

目的:探讨利用恒定负荷运动方式测定最大摄氧量(VO2max)的可行性,以寻找相对简单易行且相关度较高的测试方法。方法:首先运用递增负荷运动方式测定武汉体育学院195名男大学生的VO2max,确定100%最大摄氧量速度(100%vVO2max)范围(本实验中95%的受试者100%vVO2max为16~18km·h-)。然后令1其中15名受试者分别以100%vVO2max、110%vVO2max恒定负荷运动至力竭,记录3次运动至力竭的时间(Tlim)并进行统计,分析3种运动负荷下Tlim的相关性。结果:①递增负荷与100%vVO2max恒定负荷运动所测得的VO2max无显著性差异(P>0.05),其中,15s取值时递增负荷与100%vVO2max恒定负荷运动所测得的VO2max相关系数为0.77,30s取值时两者的相关系数为0.76,相关性非常显著(P<0.01)。②递增负荷与100%vVO2max及110%vVO2max恒定负荷运动至力竭的时间Tlim分别为596.87±61.48s、214.0±77.65s和144.6±53.12s,三者两两相比均具有非常显著的差异(P<0.01),且100%和110%vVO2max恒定负荷下Tlim值显著相关,相关系数r=0.80(P<0.01)。结论:采用恒定负荷运动测定VO2max具有时间短、与递增负荷测试结果相关度较高及测试相对便捷等优点,适于在基层社区和学校应用。     

两种缺氧刺激对大学生红细胞生成素及有氧能力的影响

目的:探讨缺氧刺激对血清红细胞生成素(EPO)和转铁蛋白受体(sTfR)的影响,观察在低氧刺激环境下血液EPO分泌和血清sTfR浓度的变化规律.方法:受试者为20名身体健康的男性大学生,随机分为3组:间歇吸低氧组(n=7)、模拟高住组(n=5)和对照组(n=8).间歇吸低氧组每天30分钟吸低氧,模拟高住组每天8小时低氧环境睡眠.所有受试者在实验期均从事相同的体育技术课和理论课学习及相同的生活作息,全部实验共包括4周试验期和2周恢复期.结果:(1)对照组血清EPO浓度在实验前、中和恢复期均无明显变化.间歇吸低氧组血清EPO浓度在实验第3天、第17天、第22天,模拟高住组血清EPO浓度在实验第15天、第17天、第22天、第24天及恢复期均显著高于实验前(P＜0.05),(2)间歇吸低氧组血清sTfR浓度在实验第3天、第10天、第17天及恢复期结束均显著高于实验前(P＜0.05),而模拟高住组和对照组血清sTfR浓度在实验期和恢复期均未发生明显变化.(3)实验后间歇吸低氧组受试者VO2max与实验前比较明显增加(P＜0.05).(4)除对照组外,实验后间歇吸低氧组、模拟高住组在定量负荷运动中的心率、血乳酸与实验前相比显著下降(P＜0.05).结论:血清EPO、sTfR浓度的变化受不同低氧浓度刺激时间和方式的影响,间歇吸低氧与运动刺激相结合可增加VO2max.     

Effect of high‐intensity resistance circuit‐based training in hypoxia on aerobic performance and repeat sprint ability

Recent acute studies have shown that high‐intensity resistance circuit‐based (HRC ) training in hypoxia increases metabolic stress. However, no intervention studies have yet proven their effectiveness. This study aimed to analyze the effect of 8 weeks of HRC in hypoxia on aerobic performance, resting energy expenditure (REE ), repeat sprint ability (RSA ) and hematological variables. Twenty‐eight subjects were assigned to hypoxia (FiO₂ = 15%; HRC _hyp: n = 15; age: 24.6 ± 6.8 years; height: 177.4 ± 5.9 cm; weight: 74.9 ± 11.5 kg) and normoxia (FiO₂ = 20.9%; HRC _norm: n = 13; age: 23.2 ± 5.2 years; height: 173.4 ± 6.2 cm; weight: 69.4 ± 7.4 kg) groups. Each training session consisted of two blocks of three exercises (Block 1: bench press, leg extension, front pull down; 2: deadlift, elbow flexion, ankle extension). Each exercise was performed at 6 repetitions maximum. Participants exercised twice weekly for 8 weeks and before and after the training program blood test, REE , RSA and treadmill running test were performed. Fatigue index in the RSA test was significantly decreased in the HRC _hyp (−0.9%; P  <  .01; ES  = 2.75) but not in the HRC _norm. No changes were observed in REE and hematological variables. Absolute (4.5%; P  =  .014; ES  = 0.42) and relative (5.2%; P  =  .008; ES  = 0.43) maximal oxygen uptake (VO ₂max), speed at VO ₂max (4%; P  =  .010; ES  =  0.25) and time to exhaustion (4.1%; P  =  .012; ES  =  0.26) were significantly increased in HRC _hyp but not in the HRC _norm. No significant differences between groups were found. Compared with normoxic conditions, 8 weeks of HRC training under hypoxic conditions efficiently improves aerobic performance and RSA without changes in REE and red blood O₂‐carrying capacity.     

我国18～23岁普通男性跑节省化测试跑速研究

目的:推导适宜的单一的跑节省化(RE)负荷跑速,建立简单有效的RE测试方法。方法:区别于以往RE多点负荷测试方案,采用曲线拟合等方法,以63名新兵为实验对象,在跑台上按照负荷逐级递增的方式完成55%、60%、65%和70%VO2max时的RE测定,并测定适应期内受试者5km跑成绩;以5 km跑成绩为因变量,分别以上述4个RE相对值(R-RE)为自变量进行线性相关分析,并应用R2判定系数法判断RE与5 km跑成绩的线性关系,找出最佳线性模型;以5 km跑成绩作为效标,以R-RE与5 km跑成绩的4个相关系数r为基础进行曲线拟合,推导适宜的最佳RE负荷跑速。另外选择26名普通人对适宜的RE负荷跑速进行有效性检验。结果:11.5 km/h的跑速可作为我国18～23岁普通男性测定RE的适宜负荷,以R-RE(ml/kg/min)反映RE测试结果最适宜;有效性检验显示,以11.5 km/h的速度测定的RE结果有代表性。     

优秀游泳运动员高原训练期间VO2max、BLA和T/C值的变化

目的:探讨高原训练对优秀游泳运动员的VO2max、BLA和T/C值及VO2max相关指标的影响.方法:16名游泳运动员(男7名,女9名)进行为期9周的高原训练,分别在上高原前1周、下高原后第1周、第2周和第3周测定VO2max、BLA和T/C值及VO2max相关指标.VO2max测定采用功率自行车递增负荷运动方案,起始负荷为50W、转速60～70r/min,男子运动员递增40W/3min,女子运动员递增30W/3min,转速不变.结果:上高原前和下高原后VO2max、BLA和T/C值及VO2max相关指标发生变化,但变化的时间和程度不同;且男、女游泳运动员的VO2max、BLA和T/C值及VO2max相关指标发生不同变化.结论:高原训练对游泳运动员的VO2max、BLA和T/C值及VO2max相关指标产生影响,经过下高原后17天的训练,运动员多数指标能够恢复至上高原前水平,并在相同运动负荷下BLA值降低,表明高原训练下高原后17天游泳运动员的运动能力提高.     

中国北方汉族男性钙调神经磷酸酶基因多态性与有氧耐力表型的关联性研究

目的:探讨钙调神经磷酸酶基因多态性与有氧耐力表型初始值及耐力训练效果的关联性。方法:102名无训练史的青年健康男子完成18周有氧耐力训练,测试训练前后的VO2max和12km/h下的跑节省化(VO2)。采用PCR-RFLP和MALDI-TOFMS对钙调神经磷酸酶5个编码基因的55个单核苷酸多态性进行分型。结果:(1)VO2max初始值与单核苷酸多态性rs2850965和rs3804423关联;(2)VO2max训练敏感性与单核苷酸多态性rs3804358和rs4671887关联;(3)跑节省化的训练敏感性与单核苷酸多态性rs3739723关联。结论:钙调神经磷酸酶基因多态性可能部分解释有氧运动能力的个体差异性。     

10‐20‐30 training increases performance and lowers blood pressure and VEGF in runners

The present study examined the effect of training by the 10‐20‐30 concept on performance, blood pressure (BP), and skeletal muscle angiogenesis as well as the feasibility of completing high‐intensity interval training in local running communities. One hundred sixty recreational runners were divided into either a control group (CON; n = 28), or a 10‐20‐30 training group (10‐20‐30; n = 132) replacing two of three weekly training sessions with 10‐20‐30 training for 8 weeks and performance of a 5‐km run (5‐K) and BP was measured. VO_2max was measured and resting muscle biopsies were taken in a subgroup of runners (n = 18). 10‐20‐30 improved 5‐K time (38 s) and lowered systolic BP (2 ± 1 mmHg). For hypertensive subjects in 10‐20‐30 (n = 30), systolic and diastolic BP was lowered by 5 ± 4 and 3 ± 2 mmHg, respectively, which was a greater reduction than in the non‐hypertensive subjects (n = 102). 10‐20‐30 increased VO_2max but did not influence muscle fiber area, distribution or capillarization, whereas the expression of the pro‐angiogenic vascular endothelial growth factor (VEGF) was lowered by 22%. No changes were observed in CON. These results suggest that 10‐20‐30 training is an effective and easily implemented training intervention improving endurance performance, VO_2max and lowering BP in recreational runners, but does not affect muscle morphology and reduces muscle VEGF.     

Is there an association between PPARGC1A genotypes and endurance capacity in Chinese men?

Our purpose was to determine the possible association between genotypes of three polymorphisms (Gly482Ser, Thr394Thr and A2962G) of the peroxisome proliferator-activated receptor gamma coactivator 1 alpha (PPARGC1A) gene, on one hand, and both the pre- (baseline) and post-training levels of maximal (i.e., maximal oxygen uptake [VO2max]) and submaximal human endurance capacity (i.e., running economy [RE]). We studied 102 young males (physically active, non-athletes; age: 19+/-1 yrs) from Northern China (of Han origin) who underwent a 18-week endurance training (running) program and were tested on a treadmill (for VO2max and RE determination) before and after training. None of the VO2max and RE related traits were associated with the Gly482Ser and Thr394Thr polymorphisms at baseline or after training. The A2962G polymorphism was however associated with VO2max at baseline, as carriers of the G allele (AG+GG genotypes; n=49) had higher levels of VO2max than the AA group (n=53) (58.2+/-4.3 vs 56.3+/-3.9 mL/kg/min; P=0.017). Our results do not support previous data on Caucasians showing an association between the Gly482Ser variant and VO2max but suggest the potential role of another polymorphism (A2962G) to explain individual VO2max differences in Chinese men.     

Polymorphisms in the HBB gene relate to individual cardiorespiratory adaptation in response to endurance training

Objective

The crucial role of haemoglobin in endurance performance has been well documented. We examined whether polymorphisms in the HBB gene modified aerobic capacity.

Methods

102 recruits were trained by running 5000 m three times per week for 18 weeks. Exercise intensity progressively increased from an initial heart rate corresponding to 95% of the individual baseline ventilatory threshold during the first 10 weeks to 105% during the last 8 weeks. The phenotypes measured were running economy and VO₂max. Running economy was determined by measuring submaximal VO₂ for 5 min at a constant running speed of 12 km·h⁻¹ and VO₂max was obtained during an incremental test to exhaustion. Genomic DNA was extracted from white cells of peripheral blood and the −551C/T, intron2,+16C/G and +340 A/T genotypes were examined relative to the TAA site variants by PCR‐RFLP.

Results

Genotype distributions were in Hardy‐Weinberg equilibrium at three loci. None of the running economy and VO₂max‐related traits were associated with the three polymorphisms or haplotypes at baseline, while the training response of running economy was associated with −551C/T and intron2,+16C/G polymorphisms. Subjects homozygous for intron2,+16C/C or −551C/C had decreased oxygen cost of running compared to the other individuals.

Discussion

It was concluded that the −551C/C or intron2,+16C/C genotype might explain part of the individual variation in the cardiorespiratory adaptation to endurance training.     

中国北方汉族男性血管内皮生长因子受体2基因+4422(AC)n多态性与HiHiLo训练敏感性的关联研究

目的:探讨中国北方汉族男性血管内皮生长因子受体2(VEGFR2)基因+4422(AC)n多态性与高住高练低训(HiHiLo)训练敏感性的关联。方法:选取71名中国北方平原地区汉族男子进行30天HiHiLo,方案为每日在低氧房(O2浓度为14.8%～14.3%,模拟海拔2800～3000米)居住10小时,每周进行3次75%VO2max强度的低氧训练(O2浓度为15.4%～14.8%,模拟海拔2500～2800米),运动时间为30 min/次,其余时间在常氧环境下训练。在HiHiLo前、后测定VO2 max和SpO2。其中SpO2的测定采用低氧环境下(15.4%O2,模拟海拔约2500米)的定量负荷运动实验,运动强度为HiHiLo前个体75%VO2max,运动时间15min。基因分型采用PCR结合荧光标记复合STR-genescan方法检测+4422(AC)n多态重复次数。结果:HiHiLo后,VO2 max以及定量负荷运动中SpO2均显著性提高,且(AC)11/(AC)11基因型者rVO2max的训练敏感性显著高于(AC)11/(AC)12基因型者。结论:VEGFR2基因+4422(AC)n多态性与HiHiLo后rVO2 max训练敏感性有关联,而与定量负荷下SpO2训练敏感性无关联。提示+4422(AC)n多态性可以作为预测低氧训练效果的分子遗传学标记,但还需加大样本量进一步验证。     

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。     

Effects of nitrate supplementation in trained and untrained muscle are modest with initial high plasma nitrite levels

Nitrate () supplementation resulting in higher plasma nitrite () is reported to lower resting mean arterial blood pressure (MAP) and oxygen uptake (VO₂) during submaximal exercise in non‐athletic populations, whereas effects in general are absent in endurance‐trained individuals. To test whether physiologic effects of supplementation depend on local muscular training status or cardiovascular fitness, male endurance‐trained cyclists (CYC, n=9, VO₂‐max: 64±3 mL/min/kg; mean±SD) and recreational active subjects serving as a control group (CON, n=8, 46±3 mL/min/kg), acutely consumed nitrate‐rich beetroot juice ([] ~9 mmol) (NIT) or placebo (PLA) with assessment of resting MAP and energy expenditure during moderate intensity (~50% VO₂‐max) and incremental leg cycling (LEG‐ex) and arm‐cranking exercise (ARM‐ex). NIT increased (P<.001) resting plasma by ~1200% relative to PLA. Plasma increased ~25% (P<.01) with a significant change only in CYC. LEG‐ex VO₂ (~2.60 L/min), ARM‐ex VO₂ (~1.14 L/min), and resting MAP (~87 mm Hg) remained unchanged for CYC, and similarly for CON, no changes were observed for LEG‐ex VO₂ (~2.03 L/min), ARM‐ex VO₂ (~1.06 L/min), or resting MAP (~85 mm Hg). VO₂‐max was not affected by supplementation, but incremental test peak power was higher (P<.05) in LEG‐ex for CYC in NIT relative to PLA (418±47 vs 407±46 W). In both CYC and CON, high initial baseline values and small increases in plasma after NIT may have lowered the effect of the intervention implying that muscular and cardiovascular training status is likely not the only factors that influence the physiologic effects of supplementation.     

Reference values for and cross‐validation of time to exhaustion on a modified Balke protocol in Norwegian men and women

The aims of the present study were to provide reference values for time to exhaustion (TTE) on a modified Balke treadmill protocol, and to perform a cross‐validation of TTE as a measure of maximal oxygen consumption (VO_2max), in Norwegian men and women 20–85 years of age. Reference values for TTE were derived from a national sample of 765 subjects. An additional sample of 119 subjects was included in the cross‐validation (total n = 884), where prediction equations for VO_2max was established. A decline in TTE was seen with increased age. Prediction of VO_2max in an independent dataset (n = 319) resulted in a R² = 0.78 and standard error of the estimate = 4.55 mL/kg/min. The observed–predicted bias was small (mean difference <1.24 mL/kg/min), whereas random error was considerable (95% limits of agreement ± 7.11–9.70 mL/kg/min) across age in both men and women. Despite limitations concerning the prediction of VO_2max on an individual level, TTE from the Balke protocol is a good measure of aerobic fitness in adults across a range of settings, and could be evaluated according to the suggested reference values.     

Cardiovascular changes with age and exercise

Various studies report a 0–22% per decade decline in circulatory function (VO_2max) with advancing age. Twelve exercising men (E) were followed for 28 years, mean age 43 and 71 years, initial to final measurement, while 12 dropouts (C) detrained for 21 years, with a mean age from first to last measurement of 48 and 69 years, respectively. VO₂ max in E changed from 45.9 to 39.4 ml · min⁻¹· kg⁻¹, 5% per decade, whereas C declined from 36.0 to 21.4 ml min⁻¹· kg⁻¹, 19% per decade. Resting blood pressure was unchanged in E, 119/75 mmHg, whereas C rose from 128/85 to 149/90 mmHg. The data suggest that regular aerobic exercise forestalls the usual loss of circulatory function with increasing age.     

Effects of sprint interval training on VO2max and aerobic exercise performance: A systematic review and meta‐analysis

Recently, several studies have examined whether low‐volume sprint interval training (SIT) may improve aerobic and metabolic function. The objective of this study was to systematically review the existing literature regarding the aerobic and metabolic effects of SIT in healthy sedentary or recreationally active adults. A systematic literature search was performed (Bibliotek.dk, SPORTDiscus, Embase, PEDro, SveMed+, and Pubmed). Meta‐analytical procedures were applied evaluating effects on maximal oxygen consumption (VO_2max). Nineteen unique studies [four randomized controlled trials (RCTs), nine matched‐controlled trials and six noncontrolled studies] were identified, evaluating SIT interventions lasting 2–8 weeks. Strong evidence support improvements of aerobic exercise performance and VO_2max following SIT. A meta‐analysis across 13 studies evaluating effects of SIT on VO_2max showed a weighted mean effects size of g = 0.63 95% CI (0.39; 0.87) and VO_2max increases of 4.2–13.4%. Solid evidence support peripheral adaptations known to increase the oxidative potential of the muscle following SIT, whereas evidence regarding central adaptations was limited and equivocal. Some evidence indicated changes in substrate oxidation at rest and during exercise as well as improved glycemic control and insulin sensitivity following SIT. In conclusion, strong evidence support improvement of aerobic exercise performance and VO_2max following SIT, which coincides with peripheral muscular adaptations. Future RCTs on long‐term SIT and underlying mechanisms are warranted.     

Cycling efficiency and time to exhaustion are reduced after acute passive stretching administration

The aim of this study was to assess the effects of acute passive stretching on cycling efficiency during an exercise of heavy intensity. After maximum aerobic power (V?O_2max) assessment, nine active males (24 ± 5 years; stature 1.71 ± 0.09 m; body mass 69 ± 7 kg; mean ± standard deviation) performed tests at 85% of V?O_2max (?₈₅) until exhaustion, with and without pre‐exercise stretching. During the tests, we determined the gas exchange, metabolic and cardiorespiratory parameters. With stretching, no differences in V?O_2max occurred (3.64 ± 0.14 vs 3.66 ± 0.07 L/min for stretching and control, respectively). During ?₈₅, pre‐exercise stretching (i) decreased time to exhaustion (t_lim) by 26% (P<0.05); (ii) increased average V?O₂ by 4% (3.24 ± 0.07 and 3.12 ± 0.07 L/min in stretching and control, respectively; P<0.05); and (iii) reduced net mechanical efficiency (e_net) by 4% (0.185 ± 0.006 and 0.193 ± 0.006 in stretching and control, respectively; P<0.05). Although acute passive stretching did not have an effect on V?O_2max, t_lim and e_net during heavy constant load exercise were significantly affected. These results are suggestive of an impairment in cycling efficiency due to changes in muscle neural activation and viscoelastic characteristics induced by stretching.