Effect of intermittent normobaric hypoxic exposure at rest on haematological,physiological, and performance parameters in multi-sport athletes

Abstract

The aim of this study was to determine whether 3 weeks of intermittent normobaric hypoxic exposure at rest was able to elicit changes that would benefit multi-sport athletes. Twenty-two multi-sport athletes of mixed ability were exposed to either a normobaric hypoxic gas (intermittent hypoxic training group) or a placebo gas containing normal room air (placebo group). The participants breathed the gas mixtures in 5-min intervals interspersed with 5-min recovery periods of normal room air for a total of 90 min per day, 5 days per week, over a 3-week period. The oxygen in the hypoxic gas decreased from 13% in week 1 to 10% by week 3. The training and placebo groups underwent a total of four performance tests, including a familiarization and baseline trial before the intervention, followed by trials at 2 and 17 days after the intervention. Time to complete the 3-km run decreased by 1.7%[95% confidence interval (CI) = ?0.6 – 3.9%] 2 days after, and by 2.3% (CI = 0.25 ? 4.4%) 17 days after, the last hypoxic episode in the training relative to the placebo group. Substantial changes in the training relative to the placebo group also included increased reticulocyte count 2 days (23.5%; CI =?1.9 to 44.9%) and 12 days (14.6%; CI = ?7.1 to 36.4%) post-exposure. The effect of intermittent hypoxic training on 3-km performance found in this study is likely to be beneficial, which suggests non-elite multi-sport athletes should expect such training to enhance performance.     

间歇低氧训练对SD大鼠心肌肌球蛋白重链表达的影响

目的:观察在间歇低氧及游泳运动的影响下,SD大鼠心肌细胞肌球蛋白重链α-MHC、β-MHC两种异构型表达的变化,探讨间歇低氧训练对心肌功能影响的可能分子机制.方法:将128只SD大鼠随机分成对照组、间歇低氧训练组、游泳训练组及间歇低氧+游泳训练组,经过4周的训练,采用SDS-PAGE法观察SD大鼠心肌细胞肌球蛋白重链α-MHC、β-MHC表达的变化. 结果:间歇低氧及游泳训练可引起α-MHC表达不同程度的上调,同时β-MHC表达不同程度的下调.结论:在间歇低氧及运动性机械刺激作用的过程中,心肌细胞通过上调α-MHC和下调β-MHC的表达,来适应环境氧分压降低的变化和运动刺激的作用.     

The effect of exercise interventions on resting metabolic rate: A systematic review and meta-analysis

ABSTRACT

The systematic review and meta-analysis evaluated the effect of aerobic, resistance and combined exercise on RMR (kCal·day^-1) and performed a methodological assessment of indirect calorimetry protocols within the included studies. Subgroup analyses included energy/diet restriction and body composition changes. Randomized control trials (RCTs), quasi – RCTs and cohort trials featuring a physical activity intervention of any form and duration excluding single exercise bouts were included. Participant exclusions included medical conditions impacting upon RMR, the elderly (≥65 years of age) or pregnant, lactating or post-menopausal women. The review was registered in the International Prospective Register of Systematic Reviews (CRD 42,017,058,503). 1669 articles were identified; 22 were included in the qualitative analysis and 18 were meta-analysed. Exercise interventions (aerobic and resistance exercise combined) did not increase resting metabolic rate (mean difference (MD): 74.6 kCal·day^-1[95% CI: ?13.01, 161.33], P = 0.10). While there was no effect of aerobic exercise on RMR (MD: 81.65 kCal·day^-1[95% CI: ?57.81, 221.10], P = 0.25), resistance exercise increased RMR compared to controls (MD: 96.17 kCal·day^-1[95% CI: 45.17, 147.16], P = 0.0002). This systematic review effectively synthesises the effect of exercise interventions on RMR in comparison to controls; despite heterogenous methodologies and high risk of bias within included studies.     

间歇性低氧训练的原理及应用

间歇性低氧训练是对传统高原训练的一种补充和创新,是指在平原借助低氧仪,使运动员间断性地吸人低于正常氧分压的气体,造成体内适度缺氧,导致一系列抗缺氧生理、生化适应,以达到提高有氧代谢力为目的的训练方法。分析了间歇性低氧训练对呼吸系统、血液、心血管系统、骨骼肌、细胞内物质代谢、心肺功能、抗过氧化物反应系统的作用原理以及其优势,为实践运用间歇性低氧训练提供理论参考。     

The time-frame of acute resistance exercise effects on football skill performance: The impact of exercise intensity

Abstract

The purpose of this study was to determine the recovery rate of football skill performance following resistance exercise of moderate or high intensity. Ten elite football players participated in three different trials: control, low-intensity resistance exercise (4 sets, 8–10 repetitions/set, 65–70% 1 repetition maximum [1RM]) and high-intensity resistance exercise (4 sets, 4–6 repetitions/set, 85–90% 1RM) in a counterbalanced manner. In each experimental condition, participants were evaluated pre, post, and at 24, 48, 72 h post exercise time points. Football skill performance was assessed through the Loughborough Soccer Passing Test, long passing, dribbling, shooting and heading. Delayed onset muscle soreness, knee joint range of motion, and muscle strength (1RM) in squat were considered as muscle damage markers. Blood samples analysed for creatine kinase activity, C-reactive protein, and leukocyte count. Passing and shooting performance declined (P < 0.05) post-exercise following resistance exercise. Strength declined post-exercise following high-intensity resistance exercise. Both trials induced only a mild muscle damage and inflammatory response in an intensity-dependent manner. These results indicate that football skill performance is minimally affected by acute resistance exercise independent of intensity suggesting that elite players may be able to participate in a football practice or match after only 24 h following a strength training session.     

间歇性低氧训练、疲劳和恢复对H反射参数影响初探

目的:研究间歇性低氧训练(IHT),以及训练结束后的运动性疲劳与恢复过程对H反射各参数的影响.方法:用自制低氧混合气体,对8名短跑运动员进行每日10～11%O2的循环低氧刺激,持续两周,在IHT前后以及IHT之后的疲劳与恢复过程进行H反射各参数测试.结果:两周IHT训练前后M波振幅增加,H波潜伏期升高,差异具有显著性;疲劳后即刻H渡振幅下降,恢复期前三分钟H波振幅显著降低,随后逐渐恢复,在恢复期第15分钟,H波振幅显著升高.结论:H反射是敏感的反映低氧训练以及疲劳对短跑运动员神经系统的影响指标,并提示H反射低氧训练的改变以及运动性疲劳前后以及恢复期的变化与两周低氧训练引起的H反射通路脊髓水平的适应性有关.     

间歇低氧运动对肥胖大鼠食欲的影响及其机制分析

探讨间歇低氧运动对营养性肥胖SD大鼠摄食的影响并分析其可能机制,为间歇低氧减肥提供理论依据。为此,通过对雄性SD大鼠饲喂高脂饲料建立营养性肥胖模型,然后进行为期4周的间歇低氧运动(运动速度为20 m/min,?(O2)前2周为15.4%,后2周为14.5%)。间歇低氧运动组进行4周间歇低氧运动刺激。结果发现:与常氧安静组相比,常氧运动组和间歇低氧运动组肥胖SD大鼠下丘脑瘦素和瘦素受体含量增加(常氧运动组P<0.05,间歇低氧运动组P<0.01),大鼠的每日摄食量减少。与常氧运动组相比,间歇低氧运动组肥胖SD大鼠下丘脑瘦素和瘦素受体含量增加(瘦素P<0.05,瘦素受体P<0.01)。结果说明:1)间歇低氧运动抑制了肥胖大鼠的食欲,减少了摄食量,减缓了大鼠体重的增加,并且间歇低氧效果比单纯运动效果好;2)间歇低氧运动抑制大鼠食欲可能与大鼠下丘脑瘦素和瘦素受体含量增加,进而抑制神经肽Y有关。     

The physiological effects of concurrent strength and endurance training sequence: A systematic review and meta-analysis

We conducted a systematic literature review and meta-analysis to assess the chronic effects of the sequence of concurrent strength and endurance training on selected important physiological and performance parameters, namely lower body 1 repetition maximum (1RM) and maximal aerobic capacity (VO₂max/peak). Based on predetermined eligibility criteria, chronic effect trials, comparing strength-endurance (SE) with endurance-strength (ES) training sequence in the same session were included. Data on effect sizes, sample size and SD as well other related study characteristics were extracted. The effect sizes were pooled using, Fixed or Random effect models as per level of heterogeneity between studies and a further sensitivity analyses was carried out using Inverse Variance Heterogeneity (IVHet) models to adjust for potential bias due to heterogeneity. Lower body 1RM was significantly higher when strength training preceded endurance with a pooled mean change of 3.96 kg (95%CI: 0.81 to 7.10 kg). However, the training sequence had no impact on aerobic capacity with a pooled mean difference of 0.39 ml.kg.min^?1 (95%CI: ?1.03 to 1.81 ml.kg.min^?1). Sequencing strength training prior to endurance in concurrent training appears to be beneficial for lower body strength adaptations, while the improvement of aerobic capacity is not affected by training order.     

不同模式低氧及递增负荷训练对心肌肌球蛋白重链表达的影响

目的:主要通过间歇低氧训练和高住低练两种低氧训练模式观察运动即刻状态下大鼠心肌肌球蛋白重链比例表达。方法:48只大鼠分为6组,四周递增负荷跑台实验后,测得心肌肌球蛋白重链及相关指标。结果:①高住低练组较间歇低氧运动组,左心室心肌运动性肥大较为明显(P<0.05);②运动组心肌肌球蛋白β-MHC向α-MHC转化率高于常氧对照组,高住低练组高于间歇低氧运动组,且存在显著性差异(P<0.05);结论:本次实验中就心肌肌球蛋白重链等相关指标而言,高住低练组是本实验设计六组中最为理想的训练模式。     

高水平自行车耐力运动员高强度间歇训练方案优化研究述评

就高水平耐力自行车运动员高强度间歇训练方案最优化的研究加以总结和展望.高水平自行车耐力运动员高强度间歇训练方案优化的研究主要涉及训练强度、持续时间、组数,间歇恢复形式(主动或被动)、间歇恢复时间,踏车节奏和成绩模型.这些变量需要根据训练时期、训练状态、个体身体反应来进行实践.     

Effects of resistance training on performance in previously trained endurance runners: A systematic review

The aim of this work was to identify, synthesize and evaluate the results of randomized controlled trials examining the effects of resistance training on performance indicators in previously trained endurance runners. A database search was carried out in PubMed, Science Direct, OvidSPMedLine, Wiley, Web of Science, ProQuest and Google Scholar. In accordance with the PRISMA checklist, 18 published articles dated prior to May 2016 involving 321 endurance runners were reviewed using the PEDro scale. Resistance training led to general improvements in muscular strength, running economy, muscle power factors, and direct performance in distances between 1,500 and 10,000 m. Such improvements were not accompanied by a significant increase in body mass or signs of overtraining. However, improvements did not occur in all cases, suggesting that they might depend on the specific characteristics of the resistance training applied. Although current evidence supports the effectiveness of resistance training to improve performance in already trained endurance runners, the methodological inconsistencies identified suggest that the results should be interpreted with caution. Future studies ought to investigate the benefits of resistance training in endurance runners while considering the existence of possible differentiated effects based on the specific characteristics of the resistance training carried out.     

The effects of combined glucose-electrolyte and sodium bicarbonate ingestion on prolonged intermittent exercise performance

Abstract

This study examined the effects of combined glucose and sodium bicarbonate ingestion prior to intermittent exercise. Ninemales (mean ± s age 25.4 ± 6.6 years, body mass 78.8 ± 12.0 kg, maximal oxygen uptake ([Vdot]O_2max) 47.0 ± 7ml · kg · min^?1) undertook 4 × 45 min intermittent cycling trials including 15 × 10 s sprints one hour after ingesting placebo (PLA), glucose (CHO), sodium bicarbonate (NaHCO₃) or a combined CHO and NaHCO₃ solution (COMB). Post ingestion blood pH (7.45 ± 0.03, 7.46 ± 0.03, 7.32 ± 0.05, 7.32 ± 0.01) and bicarbonate (30.3 ± 2.1, 30.7 ± 1.8, 24.2 ± 1.2, 24.0 ± 1.8 mmol · l^?1) were greater for NaHCO₃ and COMB when compared to PLA and CHO, remaining elevated throughout exercise (main effect for trial; P < 0.05). Blood lactate concentration was greatest throughout exercise for NaHCO₃ and COMB (main effect for trial; P < 0.05). Blood glucose concentration was greatest 15 min post-ingestion for CHO followed by COMB, NaHCO₃ and PLA (7.13 ± 0.60, 5.58 ± 0.75, 4.51 ± 0.56, 4.46 ± 0.59 mmol · l^?1, respectively; P < 0.05). Gastrointestinal distress was lower during COMB compared to NaHCO₃ at 15 min post-ingestion (P < 0.05). No differences were observed for sprint performance between trials (P = 1.00). The results of this study suggest that a combined CHO and NaHCO₃ beverage reduced gastrointestinal distress and CHO availability but did not improve performance. Although there was no effect on performance an investigation of the effects in more highly trained individuals may be warranted.     

The influence of exercise and physical fitness status on attention: a systematic review

ABSTRACT

Background: Exercise helps many aspects of cognition, but at this time no review has summarized the literature on the association of exercise and physical fitness with attention. Method: A systematic search was conducted on PubMed, ISI Web of Knowledge, and Scopus databases. After inclusion criteria assessment, a final pool of 44 articles was included. A number of behavioral and neurophysiological indices of attention were examined. Results: The majority of studies showed an increase in performance of attention. Acute exercise results in greater enhancement of attention in those who are active. There was an association of aerobic fitness and attention in the young and old, but not in young adults. Aerobic exercise training interventions generally resulted in positive changes, while some resistance training studies detected no evidence of an effect. Not all forms of exercise were effective. Shorter interventions were inferior with respect to longer ones. Most studies were rated with a moderate methodological quality. Conclusion: There is an association of aerobic exercise (acute and chronic) and aerobic fitness with attention. Future research should determine the dose and mechanisms by which different forms of physical activity and exercise may influence the development of different components of attention along the lifespan.     

Self-reported tolerance of the intensity of exercise influences affective responses to and intentions to engage with high-intensity interval exercise

This study investigated the effect of self-reported tolerance of the intensity of exercise on affective responses to, self-efficacy for and intention to repeat low-volume high-intensity interval exercise (HIIE). Thirty-six healthy participants (mean age 21 ± 2 years) were split into high tolerance (HT; n = 19), low tolerance (LT; n = 9), and very low tolerance (VLT; n = 8) of exercise intensity groups. Participants completed 10 × 6 s cycle sprints with 60 s recovery. Affective valence and perceived activation were measured before exercise, after sprints 2, 4, 6, 8, 10, and 20 min post-HIIE. Intention and self-efficacy were assessed 20 min post-HIIE. Affective valence was significantly lower in VLT vs. LT (P = 0.034, d = 1.01–1.14) and HT (P = 0.018, d = 1.34–1.70). Circumplex profiles showed a negative affective state in VLT only. The VLT group had lower intentions to repeat HIIE once and three times per week than HT (P < 0.001, d = 1.87 and 1.81, respectively) and LT (P = 0.107, d = 0.85; P = 0.295, d = 0.53, respectively). Self-efficacy was not influenced by tolerance. Self-reported tolerance of exercise intensity influences affective responses to and intentions to engage with HIIE.     

Movement concepts approach in studies on flamenco dancing: A systematic review

Background: Flamenco is a highly emotional and demanding dance form. It is important to understand how the dancer’s body works in order to improve fitness levels and reduce injuries. Thus, our investigation reviewed studies on kinesiological aspects of flamenco over recent years. Methods: The review was restricted to experimental studies. Literature searches were conducted using the following databases: PubMed, Scopus, and Ebsco: SPORTDiscus with Full Text, Medline, Health Source: Nursing/Academic Edition, Health Source – Consumer Edition. After limiting the search, 180 potential articles remained for analysis. Results: A total of 27 papers on different aspects of flamenco dance were finally selected: biomechanics (14), podiatry (6), injury incidence (3), anthropometry (2), and physiology (2). These studies have applied well-established methods from sports studies. However, we noted a number of potential limitations when applied to flamenco. Conclusions: The evidence from this review shows that flamenco dancing demands high levels of effort. Further research is required to understand how the dancer’s body works in order to improve fitness levels and reduce injuries. Most of the results presented here are consistent among studies. However, there is a great scarcity of research addressing flamenco movement in a more comprehensive perspective.     

Systematic review of the acute and chronic effects of high-intensity interval training on executive function across the lifespan

ABSTRACT

Research regarding the effects of high-intensity interval training (HIIT) on executive function has grown exponentially in recent years. However, there has been no comprehensive review of the current state of literature. Therefore, the aim of this systematic review is to summarize previous research regarding the acute and chronic effects of HIIT on executive function across the lifespan and highlight future research directions. The results indicated that acute bouts of HIIT has a positive effect on inhibition in children/adolescents and adults, and further that chronic HIIT benefits inhibition and working memory in children. More research employing chronic interventions, focusing on middle-aged and older adults, and examining the effects on the working memory and cognitive flexibility domains of executive function are needed. Future research should also focus on a) the use of stronger research designs, b) the effects of HIIT dosage/modality, c) consideration of individual differences, d) possible underlying mechanisms, and e) examining the feasibility of translating HIIT to real-word settings.     

Factors that affect heart rate variability following acute resistance exercise: A systematic review and meta-analysis

BackgroundThere is controversial evidence regarding the effect of acute resistance exercise (ARE) on heart rate variability (HRV) parameters, which indicates the activities of the cardiac autonomic nervous system. The aim of this study was to perform a systematic review and meta-analysis of the literature on the effect of ARE on HRV parameters and identify its possible moderating factors.MethodsThe PubMed–Medline, Web of Science, SPORTDiscus, and Cochrane Library databases were searched. The Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) declaration was followed, and the methodological quality of the studies was evaluated. The level of significance was set at p ≤ 0.05. Twenty-six studies met the inclusion criteria. Main effect analyses between pre- and post-test interventions demonstrated an increase in normalized units low frequency (p < 0.001; standardized mean difference (SMD) = 0.78; 95% confidence interval (95%CI): 0.46?1.11) and low frequency/high frequency ratio (p < 0.001; SMD = 0.82; 95%CI: 0.64?0.99) and a decrease in standard deviation of the normal-to-normal (NN) interval (p < 0.001; SMD = –0.58; 95%CI: –0.85 to –0.30), root mean square of the successive differences (p < 0.001; SMD = –1.01; 95%CI: –1.29 to –0.74), and normalized units high frequency (p < 0.001; SMD: –1.08; 95%CI: –1.43 to –0.73) following ARE in healthy individuals range: 15 ± 1 to 48 ± 2 years; mean ± SD).ResultsThere were differences between the subgroups in the number of sets used in an exercise (p = 0.05) for root mean square of the successive differences, as well as for exercise intensity (p = 0.01) and rest between sets (p = 0.05) for normalized units high frequency. Interestingly, there were differences between the subgroups in training volume for root mean square of the successive differences (p = 0.01), normalized units high frequency (p = 0.003) and normalized units low frequency (p = 0.02).ConclusionOverall, there was a withdrawal of cardiac parasympathetic and activation of cardiac sympathetic modulations following ARE, and these changes were greater with higher training volume ～30 min after ARE in healthy individuals. Furthermore, the number of sets, intensity, and rest between sets affected HRV parameters. However, gender, body mass index, and training status did not influence the changes in HRV parameters as a response to ARE.     

Validity and reliability of the Moxy oxygen monitor during incremental cycling exercise

Introduction: The Moxy is a novel, cutaneously placed muscle oxygen monitor which claims to measure local oxygen saturation (SmO₂) and total haemoglobin (THb) using near-infrared spectroscopy. If shown to be reliable, its data storage and telemetric capability will be useful for assessing localised O₂ usage during field-based exercise. This study investigated the reliability of the Moxy during cycling and assessed the correlations between its measurements, whole-body O₂ consumption (VO₂) and heart rate (HR). Methods: Ten highly trained cyclists performed an incremental, step-wise cycling protocol on two occasions while wearing the Moxy. SmO₂, THb, VO₂ and HR were recorded in the final minute of each five-minute stage. Data were analysed using Spearman’s Order-Rank Coefficient (SROC), Intraclass Correlation (ICC), and Coefficient of Variance (COV). Significance was set at p?≤?.05. Results: SmO₂ showed a ‘strong’ or ‘very large’ correlation between trials (SROC: r?=?0.842–0.993, ICC: r?=?0.773–0.992, p?≤?.01) and was moderately correlated with VO₂ and HR (r?=??0.71–0.73, p?≤?.01). SmO₂ showed a moderate to high reliability at low intensities, but this decreased as relative exercise intensity increased. THb showed poor correlations between tests and with the other measured variables, but was highly reliable at all power outputs. Conclusions: The Moxy is a reliable device to measure SmO₂ at low to moderate intensities, but at higher intensities, greater variation in measurements occurs, likely due to tissue ischaemia or increased movement artefacts due to more frequent muscular contractions. THb has low variation during exercise, and does not appear to be a valid indicator of muscle oxygenation.     

Effects of strength training on physical fitness and sport-specific performance in recreational,sub-elite,and elite rowers: A systematic review with meta-analysis

ABSTRACT

The purpose of this systematic review with meta-analysis was to examine the effects of strength training (ST) on selected components of physical fitness (e.g., lower/upper limb maximal strength, muscular endurance, jump performance, cardiorespiratory endurance) and sport-specific performance in rowers. Only studies with an active control group were included if they examined the effects of ST on at least one proxy of physical fitness and/or sport-specific performance in rowers. Weighted and averaged standardized mean differences (SMD) were calculated using random-effects models. Subgroup analyses were computed to identify effects of ST type or expertise level on sport-specific performance. Our analyses revealed significant small effects of ST on lower limb maximal strength (SMD = 0.42, p = 0.05) and on sport-specific performance (SMD = 0.32, p = 0.05). Non-significant effects were found for upper limb maximal strength, upper/lower limb muscular endurance, jump performance, and cardiorespiratory endurance. Subgroup analyses for ST type and expertise level showed non-significant differences between the respective subgroups of rowers (p ≥ 0.32). Our systematic review with meta-analysis indicated that ST is an effective means for improving lower limb maximal strength and sport-specific performance in rowers. However, ST-induced effects are neither modulated by ST type nor rowers’ expertise level.     

我国甲A足球运动员平原及高原训练时血清睾酮、红细胞有形成分和心血管机能反应特点

与平原相比我国足球运动员高原训练血清睾酮无明显变化,血液有形成份中RBC、HB和RBC平均体积及RBC体积分布宽度显著性增加。中等强度运动时高原心率反应大于平原,而大强度运动时则低于平原心率反应,同时12min跑成绩也劣于平原。说明RBC、HB的增加是单纯高原轻度缺氧所致,限制高原大强度运动能力的因素仍然是心血管机能。