The Influence of Hydration on Anaerobic Performance

This review examines the influence of dehydration on muscular strength and endurance and on single and repeated anaerobic sprint bouts. Describing hydration effects on anaerobic performance is difficult because various exercise modes are dominated by anaerobic energy pathways, but still contain inherent physiological differences. The critical level of water deficit (～ 3–4%; mode dependent) affecting anaerobic performance is larger than the deficit (～ 2%) impairing endurance performance. A critical performance-duration component (> 30 s) may also exist. Moderate dehydration (> 3% body weight; precise threshold depends on work/recovery ratio) impairs repeated anaerobic bouts, which place an increased demand on aerobic metabolism. Interactions between dehydration level, dehydration mode, testing mode, performance duration, and work/recovery ratio during repeated bouts make the dehydration thresh-old influencing anaerobic performance mode dependent.     

Endurance and sprint benefits of high-intensity and supramaximal interval training

Abstract

This study examined the effect of two different interval training programs–high-intensity interval training (HIT) and supramaximal interval training (SMIT)–on measures of sprint and endurance performance. Physically active individuals (Females: n=32; age 19.3, s=2.2 years; mass 67.6, s=9.1 kg; stature 172.7, s=6.6 cm. Males: n=23; age 20.0, s=2.7 years; mass 71.3, s=8.3 kg; stature 176.6, s=5.8 cm) completed pre-testing that comprised (1) 3000 m time-trial, (2) 40 m sprint, and (3) repeated sprint ability (RSA–6×40 m sprints, 24 s active recovery) performance. Participants were then matched for average 3000 m running velocity (AV) and randomly assigned to one of three groups: (i) HIT, n=19, 4 min at 100% AV, 4 min passive recovery, 4–6 bouts per session; (ii) SMIT, n=20, 30 s at 130% AV, 150 s passive recovery, 7–12 bouts per session; and (iii) control group, n=16, 30 min continuous running at 75% AV. Groups trained three times per week for six weeks. When time to complete each test were compared among groups: (i) improvements in 3000 m time trial performance were greater following SMIT than continuous running, and (ii) improvements in 40 m sprint and RSA performance were greater following SMIT than HIT and continuous running. In addition, a gender effect was observed for the 3000 m time trial only, where females changed more following the training intervention than males. In summary, for concurrent improvements in endurance, sprint and repeated sprint performance, SMIT provides the greatest benefits for physically active individuals.     

Effects of short-term Rhodiola Rosea (Golden Root Extract) supplementation on anaerobic exercise performance

The purpose of this study was to examine the effects of short-term Rhodiola Rosea (Golden Root Extract (GRE)) supplementation on repeated Wingate performance. Eleven physically active college aged females were recruited for this study. In a within groups counterbalanced study design, participants were supplemented with either 1,500 mg/day of GRE or placebo (gluten-free cornstarch) for 3 days. Participants also took an additional 500 mg dose of corresponding treatment 30 minutes prior to testing of each trial. During each exercise trial, participants completed 3 × 15-second Wingate Anaerobic Tests (WAnTs) separated by 2-minute active recovery periods. Each exercise trial was separated by a 7 day washout period. Over the 3 × 15-second WAnTs, mean watts (p = 0.017, ES = 0.55), mean anaerobic capacity (p = 0.025, ES = 0.96), mean anaerobic power (p = 0.03, ES = 1.07), mean peak watts (p = 0.029,ES = 0.46), and mean total work (p = 0.017, ES = 0.49) were higher in the GRE treatment trial versus placebo. However, mean fatigue index (p = 0.094, ES = 0.39) was unaffected regardless of treatment. Our results show that GRE supplementation enhanced anaerobic exercise performance as measured through repeated WAnTs. GRE may possess ergogenic benefits and findings hold important implications for boosting anaerobic performance in repeated anaerobic bouts of exercise.     

力量训练提升马拉松跑者耐力运动表现的研究进展及训练策略

有氧能力的高低是马拉松跑者能否取得优异成绩的关键。最大摄氧量、乳酸阈和跑步经济性是衡量运动员有氧能力和耐力运动表现的关键指标,也是长跑训练效果的核心考量。由于力量和耐力训练对机体产生不同的训练刺激,教练员和运动员很少将力量训练作为提升耐力运动表现的手段,以防止有氧能力受到负面影响。通过对大量文献梳理发现,力量训练可以在不影响机体最大摄氧量和乳酸阈值的前提下,通过改善神经肌肉功能、转换肌纤维类型以及增强肌肉肌腱刚度和利用弹性势能的能力,提高跑步经济性和无氧能力,改善运动员耐力运动表现。本文基于对力量、耐力训练的生理学适应的探讨,总结不同形式力量训练对耐力运动表现的影响与作用机制,并为马拉松选手科学安排力量训练提出建议,从而优化其耐力运动表现。     

皮划艇项目有氧能力的评价方法

有氧能力是皮划艇项目运动能力的基础,作为高强度、高乳酸的无氧糖酵解和有氧氧化供能的项目,皮划艇运动员的有氧耐力水平对运动成绩有着决定性的影响。结合皮划艇项目特征及供能特点,分析皮划艇有氧能力测试过程中多种评价方法（3 000 m耐力跑测试、最大摄氧量测试、高强度负荷后血乳酸测试和无氧阈测试等）。在诸多有氧能力评价方法中无氧阈测试有着广泛而有效地使用历史,其中以4 mmol/L乳酸阈（AT4）与个体乳酸阈（IAT）应用最为广泛,而心率无氧阈或可成为皮划艇项目无氧阈研究的新热点。     

Effects of high-intensity interval training on canoeing performance

The purpose of this study was to compare the effects of high-intensity interval training (HIIT) and moderate-intensity continuous training (MICT) utilizing a canoeing ergometer on endurance determinants, as well as aerobic and anaerobic performances among flat-water canoeists. Fourteen well-trained male flat-water canoeists were divided into an HIIT group or an MICT group. All subjects performed a continuous graded exercise test (GXT) and three fixed-distance (200, 500, and 1000?m) performance tests on a canoeing ergometer to determine canoeing economy, peak oxygen uptake (VO₂peak), and power at VO₂peak, and to calculate the critical velocity (CV) and anaerobic work capacity before and after the training programmes. The training programme involved training on a canoeing ergometer three times per week for four weeks. HIIT consisted of seven 2 min canoeing bouts at an intensity of 90% VO₂peak separated by 1 min of rest. The MICT group was trained at an intensity of 65% VO₂peak continuously for 20 min. After four weeks of training, performance in the 200-m distance test and the power at VO₂peak significantly improved in the HIIT group; performance in the 500?m and 1000?m distances and CV significantly improved in the MICT group. However, all variables were not significantly different between groups. It is concluded that HIIT for four weeks is an effective training strategy for improvement of short-distance canoeing performance. In contrast, MICT improves middle-distance canoeing performances and aerobic capacity.     

青少年速滑运动员有氧耐力训练的心率负荷模式

科学地利用心率变化情况进行有氧耐力训练监测,对于广大基层速度滑冰教练员是简单、实用和可行的训练方法。通过文献资料、逻辑分析等方法,阐述了公式法、生理反应法、呼吸变量法等心率无氧阈测算方法;并对心率无氧阈、心率负荷与训练强度的关系等问题进行了研究;基于心率无氧阈分析,提出了培养青少年速滑运动员有氧耐力的心率负荷带训练模式,心率负荷训练间歇模式,以及不同年龄的青少年速滑运动员有氧耐力训练的心率负荷参考值对应表。     

不同无氧阈测定方法比较及其在中长跑训练中的应用

本文比较了各种无氧阈测值:通气阈(VT),4mmol乳酸阈(LT_4),血乳酸开始升高(LT_(OBLA)),个体无氧阈(IAT),血乳酸最大稳态(maxLass)和心率拐点(HRd)。发现各测值之间高度相关,但是maxLass与其它测值之间存在不同程度的差异,为AT在训练中的应用提供了有价值的生理依据。继而探讨了LT_4百分比强度对控制中长跑训练,改善运动员肌肉氧化代射能力,提高运动成绩的意义。     

Effect of creatine supplementation on phosphocreatine resynthesis,inorganic phosphate accumulation and pH during intermittent maximal exercise

In this study, we examined the effect of creatine ingestion on muscle power output, muscle phosphocreatine resynthesis, inorganic phosphate and pH during repeated brief bouts of maximal exercise. Nine healthy males performed maximal plantar flexion before and after creatine ingestion (20 g x day(-1) for 6 days). The experimental protocol consisted of five 8 s bouts (bouts 1-5) interspersed with 30 s recovery, followed by bouts 6 (8 s) and 7 (16 s) separated by 1 and 2 min, respectively. Muscle phosphocreatine, inorganic phosphate and pH were estimated every 16 s by 31P magnetic resonance spectroscopy. After creatine ingestion, muscle power output increased by approximately 5% (P< 0.05) from bouts 3 to 7 and muscle phosphocreatine resynthesis increased (P< 0.05) during 10 min recovery. The higher phosphocreatine concentration observed after only 30 s of recovery was accompanied by lower inorganic phosphate accumulation and higher pH. Strong correlations were found between exercise power restoration and the corresponding pre-exercise phosphocreatine and inorganic phosphate concentrations and muscle pH after creatine ingestion. The better maintenance of muscle power output observed after creatine ingestion was attributed to a higher rate of phosphocreatine resynthesis, lower accumulation of inorganic phosphate and higher pH.     

不同快速降体重量对肌肉功能的影响

目的:探讨不同快速降体重量对肌肉功能的影响;方法:以12名健康男生为实验对象,测定脱水前(0%bw l)、桑拿脱水快速降体重2%(2%bw l)、桑拿脱水快速降体重4%(4%bw l)这3种不同体重状态下最大等速肌力、等速肌耐力与无氧作功能力;在测定无氧作功能力时,结合运用主观用力程度等级评价量表(RPE),对肌肉功能进行系统评价;结果:1)2%bw l和4%bw l对肌肉的最大等速力量均没有削弱作用;2%bw l后,屈肘肌群的最大等速肌力反而增大。2)2%bw l对屈、伸肘肌群以及屈、伸膝肌群的等速肌耐力均没有影响;4%bw l后,屈肘肌群与屈、伸膝肌群的等速肌耐力不变,而伸肘肌群的等速肌耐力显著性下降。3)2%bw l和4%bw l对下肢的无氧耐力没有削弱作用。     

Analysis of repeated high-intensity running performance in professional soccer

The aims of this study were twofold: (1) to characterize repeated high-intensity movement activity profiles of a professional soccer team in official match-play; and (2) to inform and verify the construct validity of tests commonly used to determine repeated-sprint ability in soccer by investigating the relationship between the results from a test of repeated-sprint ability and repeated high-intensity performance in competition. High-intensity running performance (movement at velocities >19.8 km · h(-1) for a minimum of 1 s duration) was measured in 20 players using computerized time-motion analysis. Performance in 80 French League 1 matches was analysed. In addition, 12 of the 20 players performed a repeated-sprint test on a non-motorized treadmill consisting of six consecutive 6 s sprints separated by 20 s passive recovery intervals. In all players, most consecutive high-intensity actions in competition were performed after recovery durations ≥61 s, recovery activity separating these efforts was generally active in nature with the major part of this spent walking, and players performed 1.1 ± 1.1 repeated high-intensity bouts (a minimum of three consecutive high-intensity bouts with a mean recovery time ≤20 s separating efforts) per game. Players reporting lowest performance decrements in the repeated-sprint ability test performed more high-intensity actions interspersed by short recovery times (≤20 s, P < 0.01 and ≤30 s, P < 0.05) compared with those with higher decrements. Across positional roles, central-midfielders performed more high-intensity actions separated by short recovery times (≤20 s) and spent a larger proportion of time running at higher intensities during recovery periods, while fullbacks performed the most repeated high-intensity bouts (statistical differences across positional roles from P < 0.05 to P < 0.001). These findings have implications for repeated high-intensity testing and physical conditioning regimens.     

Plasma testosterone and cortisol responses to prolonged sculling in male competitive rowers.

In this study, we examined anabolic and catabolic hormone responses to a single endurance rowing training session in 12 male competitive single scull rowers. A work intensity eliciting a blood lactate concentration of 4 mmol(-1) was determined on a rowing ergometer during an endurance rowing training session lasting about 2 h (7891+/-761 s; distance covered 22.6+/-2.5 km; heart rate 136+/-7 beats x min(-1); intensity 77.4+/-3.8% of anaerobic threshold; mean +/- s). Venous blood samples were obtained before and after on-water rowing. Cortisol, testosterone and sex hormone binding globulin were measured and free testosterone and the free testosterone: cortisol ratio calculated. Blood lactate concentration did not change significantly during training (from 1.7+/-0.4 to 1.9+/-0.4 mmol x l(-1)); however, body mass was reduced (from 82.0+/-10.8 to 80.6+/-11.2 kg) and was related to the distance covered (r = -0.75). The concentrations of cortisol and testosterone did not change significantly during rowing or in the first 2 h of recovery. Free testosterone was reduced in the first 2 h of recovery, but no significant changes were observed in the free testosterone: cortisol ratio. Immediately after rowing, the concentrations of cortisol (r = 0.49) and free testosterone (r = -0.58) were related to the distance covered. Our findings indicate that a prolonged low-intensity training session results in a similar anabolic and catabolic hormone stimulus for trained rowers.     

Four weeks of high cadence training alter brain cortical activity in cyclists

ABSTRACT

Exercise at different cadences might serve as potential stimulus for functional adaptations of the brain, because cortical activation is sensitive to frequency of movement. Therefore, we investigated the effects of high (HCT) and low cadence training (LCT) on brain cortical activity during exercise as well as endurance performance.

Cyclists were randomly assigned to low and high cadence training. Over the 4-week training period, participants performed 4 h of basic endurance training as well as four additional cadence-specific exercise sessions, 60 min weekly. At baseline and after 4 weeks, participants completed an incremental exercise test with spirometry and exercise at constant load with registration of electroencephalogram (EEG).

Compared with LCT, a greater increase of frontal alpha/beta ratio was confirmed in HCT. This was based on a lower level of beta activity during exercise. Both groups showed similar improvements in maximal oxygen consumption and power at the individual anaerobic threshold.

Whereas HCT and LCT elicit similar benefits on aerobic performance, cycling at high pedalling frequencies enables participants to perform an exercise bout with less cortical activation.     

两种无氧阈测试法在赛艇运动中应用的比较研究

采用两种不同的无氧阈测试方法(乳酸法和Conconi法)对赛艇运动员进行测试,并比较其结果的相关性。结果表明:其无氧阈血乳酸值无显著性差异,无氧阈心率存在显著性差异,心率之间的差异有可能是由最大乳酸稳定状态下的个体乳酸阈最大速度引起的,在赛艇训练中以Conconi测试的心率拐点作为无氧阈训练的评定指标更有利于运动员有氧耐力水平的提高。     

优秀游泳运动员无氧耐力训练周期中IAT 和T/ C 值变化的分析研究

无氧耐力训练周期中血清睾酮(T)与血清皮质醇(C)比值和个体无氧阈(IAT)发生变化。其变化形式表现为：在训练周期中T／C值和IAT发生变化的时间和程度不同;在训练周期中男游泳运动员与女游泳运动员的T／C值和IAT变化的时间和程度不同。通过对上述不同变化的分析研究,旨在为优秀游泳运动员安排无氧耐力训练提供理论依据。     

No effect of acute ingestion of Thai ginseng ( Kaempferia parviflora ) on sprint and endurance exercise performance in humans

Abstract

Thai ginseng, Kaempferia parviflora, is widely believed among the Mong hill tribe to reduce perceived effort and improve physical work capacity. Kaempferia parviflora is consumed before their daily work. Therefore, we conducted an acute study on the effects of K. parviflora on repeated bouts of sprint exercise and on endurance exercise time to exhaustion. Two studies were conducted in college males using a randomized, double-blind, crossover design. Ninety minutes after consumption of K. parviflora or a starch placebo, participants in study 1 (n = 19) completed three consecutive maximum 30-s sprint cycling Wingate tests, separated by 3 min recovery, while participants in study 2 (n = 16) performed submaximal cycling exercise to exhaustion. Peak and mean power output decreased with successive Wingate tests, while percent fatigue and blood lactate concentration increased after the third Wingate test (P < 0.05). There were no detectable differences in any measures with or without K. parviflora. There was also no effect of K. parviflora on time to exhaustion, rating of perceived exertion or heart rate during submaximal exercise. Our results indicate that acute ingestion of K. parviflora failed to improve exercise performance during repeated sprint exercise or submaximal exercise to exhaustion. However, chronic effects or actions in other populations cannot be excluded.     

America's Cup yacht racing: Race analysis and physical characteristics of the athletes

Abstract

The America's Cup is the oldest competing trophy in sport, yet little is known of the nature and intensity of racing or the physical characteristics of the athletes. In this study, aspects of the physical demands of America's Cup yacht racing were analysed, including the intensity of exercise and activity pattern of “grinding”. Anthropometric data were collected from 92 professional male America's Cup sailors, and fitness data from a top-4 and a lower-7 ranking team during the 32nd America's Cup. Over the 135 races, mean race duration was 82 min (s = 9), with 20 tacks (s = 10) and 8 gybes (s = 3) per race. Grinding bouts were 5.5 s (s = 5.4; range: 2.2–66.3) long, with 143 exercise bouts per race and an exercise-to-rest ratio of 1:6. Mean and peak heart rate was 64% and 92% of maximum for all positions, with bowmen highest (71% and 96%). Grinders were taller, heavier, and stronger than all other positions. Body fat was similar between positions (13%, s = 4). The higher-standard team was stronger and had greater strength endurance, which probably contributed to their quicker manoeuvres. Intensity of exercise was dependent on the similarity of competing boats and the role of the athlete. The short duration and intermittent nature of grinding is indicative of predominantly anaerobic energy provision.     

Repeated sprint ability in young basketball players: one vs. two changes of direction (Part 2)

The aim of this study was to compare the training effects based on repeated sprint ability (RSA) (with one change of direction) with an intensive repeated sprint ability (IRSA) (with two changes of direction) on jump performance and aerobic fitness. Eighteen male basketball players were assigned to repeated sprint ability and intensive repeated sprint ability training groups (RSAG and IRSAG). RSA, IRSA, squat jump (SJ), countermovement jump (CMJ) and Yo-Yo intermittent recovery level 1 test were assessed before and after four training weeks. The RSA and IRSA trainings consisted of three sets of six sprints (first two weeks) and eight sprints (second two weeks) with 4-min sets recovery and 20-s of sprints recovery. Four weeks of training led to an overall improvement in most of the measures of RSA, but little evidence of any differences between the two training modes. Jump performance was enhanced: CMJ of 7.5% (P < 0.0001) and 3.1% (P = 0.016) in IRSAG and RSAG respectively. While SJ improved of 5.3% (P = 0.003) for IRSAG and 3.4% (P = 0.095) for RSAG. Conversely the Yo-Yo distance increased 21% (P = 0.301) and 34% (P = 0.017) in IRSAG and RSAG respectively. Therefore, short-term repeated sprint training with one/two changes of direction promotes improvements in both RSA and IRSA respectively but the better increase on jump performance shown a few changes on sprint and endurance performances.     

Effects of Swimming and Walking on Exercise Recovery and Subsequent Swim Performance

Abstract

Six female collegiate swimmers were used to evaluate the hypothesis that the recovery procedure after exercise will not only affect subsequent performance, but will also affect the recovery process after the subsequent performance. Each swimmer exercised for two minutes at 90% [Vdot]O₂ max on a swimming ergometer, recovered for 15 minutes by walking on land or swimming, then swam 200 yds. for time. Oxygen uptake was measured for 15 minutes after the 200 yd. swim. Venous blood, obtained after the ergometry swim, and before and after the 200 yd. swim, was analyzed for lactate. Two hundred yard swim times were not significantly affected by either the walking or swimming recovery procedures. Blood lactate after the ergometry swim averaged 96.7 ± 18 mg/100 ml. The swimming recovery reduced the lactate levels by 53.3% compared to a 38.5% reduction during the walking recovery. Significant differences in blood lactate were also noted after the 200 yd. swim, with the trials in which swimming recovery protocol was used yielding less than the trials involving the walking recovery (99 ± 8 mg/100 ml compared to 113 ± 8 mg/100 ml, respectively). The post 200 yd. swim oxygen uptakes averaged 7.74 ± 1.51 liters and were not affected by protocol. It was concluded that a 15 minute recovery period may be sufficient for repeated bouts of high intensity work lasting less than three minutes. It was also concluded that self-selection of the mode of recovery is not always the most effective for removal of blood lactate.     

Analysis of repeated high-intensity running performance in professional soccer

Abstract

The aims of this study were twofold: (1) to characterize repeated high-intensity movement activity profiles of a professional soccer team in official match-play; and (2) to inform and verify the construct validity of tests commonly used to determine repeated-sprint ability in soccer by investigating the relationship between the results from a test of repeated-sprint ability and repeated high-intensity performance in competition. High-intensity running performance (movement at velocities >19.8 km · h^?1 for a minimum of 1 s duration) was measured in 20 players using computerized time–motion analysis. Performance in 80 French League 1 matches was analysed. In addition, 12 of the 20 players performed a repeated-sprint test on a non-motorized treadmill consisting of six consecutive 6 s sprints separated by 20 s passive recovery intervals. In all players, most consecutive high-intensity actions in competition were performed after recovery durations ≥61 s, recovery activity separating these efforts was generally active in nature with the major part of this spent walking, and players performed 1.1 ± 1.1 repeated high-intensity bouts (a minimum of three consecutive high-intensity bouts with a mean recovery time ≤20 s separating efforts) per game. Players reporting lowest performance decrements in the repeated-sprint ability test performed more high-intensity actions interspersed by short recovery times (≤20 s, P < 0.01 and ≤30 s, P < 0.05) compared with those with higher decrements. Across positional roles, central-midfielders performed more high-intensity actions separated by short recovery times (≤20 s) and spent a larger proportion of time running at higher intensities during recovery periods, while fullbacks performed the most repeated high-intensity bouts (statistical differences across positional roles from P < 0.05 to P < 0.001). These findings have implications for repeated high-intensity testing and physical conditioning regimens.