Part I: Biomechanics

The purpose of this study was to determine whether the sequence of strength training before endurance training (ST/ET) is more or less effective than endurance training followed by strength training (ET/ST). Twenty‐three females and 11 males were assigned to one of three groups: ST/ET (n= 15), ET/ST (n= 15) or control (n = 4). The 7‐week training programme consisted of strength training using 10 exercises for two sets of 3–12 repetitions and running for 20–25 min at 60–90% of heart rate reserve. Maximal oxygen uptake (VO₂ max) was measured during a graded treadmill test, and muscular strength was assessed using one‐repetition maximum tests for the bench press (BP), shoulder press (SP), arm curl (AC) and leg press (LP). The VO₂ max significantly (P < 0.05) increased 6.7 and 6.2% for the ST/ET and ET/ST groups, respectively. There was no significant (P > 0.05) difference between the two experimental groups. Muscular strength significantly (P <0.05) improved by 15.2% (BP), 16.6% (SP), 17.2% (AC) and 11.9% (LP) for the ST/ET group and 19.9% (BP), 24.1% (SP), 20.9% (AC) and 14.0% (LP) for the ET/ST group. There were no significant (P > 0.05) differences between the two experimental groups for the BP, AC and LP; however, the ET/ST group increased (P < 0.05) SP strength more than the ST/ET group. In conclusion, adaptations to a combination of short‐term endurance and strength training as assessed by VO₂ max and BP, AC and LP strength appear to be independent of whether endurance training occurs prior to or following strength training.     

Altitude and endurance training

The benefits of living and training at altitude (HiHi) for an improved altitude performance of athletes are clear, but controlled studies for an improved sea-level performance are controversial. The reasons for not having a positive effect of HiHi include: (1) the acclimatization effect may have been insufficient for elite athletes to stimulate an increase in red cell mass/haemoglobin mass because of too low an altitude (<2000-2200 m) and/or too short an altitude training period (<3-4 weeks); (2) the training effect at altitude may have been compromised due to insufficient training stimuli for enhancing the function of the neuromuscular and cardiovascular systems; and (3) enhanced stress with possible overtraining symptoms and an increased frequency of infections. Moreover, the effects of hypoxia in the brain may influence both training intensity and physiological responses during training at altitude. Thus, interrupting hypoxic exposure by training in normoxia may be a key factor in avoiding or minimizing the noxious effects that are known to occur in chronic hypoxia. When comparing HiHi and HiLo (living high and training low), it is obvious that both can induce a positive acclimatization effect and increase the oxygen transport capacity of blood, at least in 'responders', if certain prerequisites are met. The minimum dose to attain a haematological acclimatization effect is >12 h a day for at least 3 weeks at an altitude or simulated altitude of 2100-2500 m. Exposure to hypoxia appears to have some positive transfer effects on subsequent training in normoxia during and after HiLo. The increased oxygen transport capacity of blood allows training at higher intensity during and after HiLo in subsequent normoxia, thereby increasing the potential to improve some neuromuscular and cardiovascular determinants of endurance performance. The effects of hypoxic training and intermittent short-term severe hypoxia at rest are not yet clear and they require further study.     

The Estimation of [Vdot]O2max from Maximal and Sub-Maximal Measurements in Males,Age 10–39

Abstract

The purpose of this study was to assess the relationship between physiological and anthropometrical variables and 15-km time trial (TT) cycling performance time. Twenty-two competitive cyclists averaged 59.7 ml · kg^–1 · min^–1 for maximal oxygen consumption ([Vdot]O_2max), 42.8 ml · kg^–1 · min^–1 for anaerobic threshold (AT), and 23.5 min for the 15 km TT race. The relationship between [Vdot]O_2max and cycling performance time was r = – 0.68, (p < .01) while the correlation between AT and performance time was r = – 0.93, (p <.01). Applying stepwise multiple regression analysis, the two-variable model of the AT and the body circumference ratio, thigh+calf:arm+chest, was found to correlate highly with cycling performance time (r =0.966). It was concluded that the successful cyclists are characterized by the ability to consume large amounts of oxygen prior to ventilatory changes associated with the anaerobic threshold as well as a larger lower to upper body circumference ratio which may favorably decrease wind resistance while cycling.     

关于二语学习者对口头纠正反馈的接纳和注意的研究

Schmidt的注意假设认为,反馈可以帮助学习者注意到自己的中介语与目的语之间的差距,有助于中介语的发展。基于此,采用口试及访谈,探究哪种纠正反馈类型更能引起学习者对语言形式的注意和更易被学习者接纳。研究表明,所有纠正反馈都能在不同程度上引起学习者对语言形式的注意;元语言提示和诱导最能引起学习者的注意;学习者的注意度越高,接纳率也越高。     

Parasympathetic activity delayed after self-paced exercise

The main purpose of this study was to compare the effect of the constant load and self-paced exercise with similar total work on autonomic control after endurance exercise. Ten physically active men were submitted to (i) a maximal incremental exercise test, (ii) a 4-km cycling time trial (4-km TT), and (iii) a constant workload test with identical total external work performed at 4-km TT. Gas exchange was measured throughout the tests, while blood lactate, heart rate, and heart rate variability (HRV) were measured during the passive recovery. Power output measured at the last lap (i.e. 3600–4000?m) of 4-km TT (316?±?89?W) was statistically higher than power output measured at the end of the constant workload exercise (211?±?42?W). The 4-km TT produced higher values of blood lactate concentration (8.8?±?2.1?mmol?L^?1) than the constant workload test (7.8?±?2.1?mmol?L^?1). The heart rate recovery measured at 60?s (constant workload: 37?±?7?bpm; 4-km TT: 30?±?6) and 120?s (constant workload: 57?±?9?bpm; 4-km TT: 51?±?9?bpm) were higher in the constant workload than in the self-paced exercise. The HRV (i.e. RMSSD30s) was statistically higher in the constant load exercise measured at 120, 420, 450, 480, 540, and 570?s than the self-paced exercise. These findings suggest that the autonomic control responses were dependent of the endurance exercise modalities, with parasympathetic activity being delayed after self-paced exercise, as evidenced by post-exercise heart rate indices.     

Energy expenditure and EPOC between water-based high-intensity interval training and moderate-intensity continuous training sessions in healthy women

The present study compared the energy expenditure (EE) during and after two water aerobics protocols, high-intensity interval training (HIIT) and moderate continuous training (CONT). A crossover randomized design was employed comprising 11 healthy young women. HIIT consisted of eight 20s bouts at 130% of the cadence associated with the maximal oxygen consumption (measured in the aquatic environment) with 10s passive rest. CONT corresponded to 30 min at a heart rate equivalent to 90–95% of the second ventilatory threshold. EE was measured during and 30 min before and after the protocols and excess post-exercise oxygen consumption (EPOC) was calculated. Total EE during session was higher in CONT (227.62 ± 31.69 kcal) compared to HIIT (39.91 ± 4.24 kcal), while EE per minute was greater in HIIT (9.98 ± 1.06 kcal) than in CONT (7.58 ± 1.07 kcal). Post-exercise EE (64.48 ± 3.50 vs. 63.65 ± 10.39 kcal) and EPOC (22.53 ± 4.98 vs.22.10 ± 8.00 kcal) were not different between HIIT and CONT, respectively. Additionally, oxygen uptake had already returned to baseline fifteen minutes post-exercise. These suggest that a water aerobics CONT session results in post-exercise EE and EPOC comparable to HIIT despite the latter supramaximal nature. Still, CONT results in higher total EE.     

耐力型及速度型运动员40％VO_(2max)稳态运动VO_2动力学特点与有氧运动能力

结果发现,运动开始后,三组受试者的VO_2皆为逐渐增加达到稳定状态,VO_2的半时反应时间、氧亏、血乳酸的变化皆为有训练者少于无训练者,耐力训练者少于速度训练者。VO_2的半时反应时间与VO_(max)相关(r=-0. 732),氧亏与VO_(2max)相关(r=-0.608),血乳酸的变化量与VO_(2max)相关(r=-0.495),提示恒定负荷稳态运动时,VO_2动力学反应与机体的训练适应有关,其主要指标VO_2的半时反应时间的大小,反映个体的有氧运动能力,可做为评定有氧运动能力的指标。并建议以VO_2半时反应时间间接推测VO_(2max)。     

高原训练对优秀自行车运动员有氧能力的影响

本文对参加11届亚运会的15名男女公路自行车运动员于1989.7和1991.8—9,分别在青海多巴(2366米)和昆明安定(1820米)进行了为期三周高原训练的观察研究。初步掌握了不同海拔高原训练时的生理机能适应规律和效应,取得了高原训练运动最和强度合理分配的经验,为今后制订和实施高原训练计划,提供了客观依据。     

不同负荷方式对大学生最大吸氧量和无氧阈的影响

通过斜度跑台、平台及功率自行车三种不同负荷方式,在渐增负荷运动中测定最大吸氧量（ＶＯ２ｍａｘ）和无氧阈（ＡＴ）,探讨了三种不同负荷方式对大学生最大吸氧量和无氧阈的影响。结果发现,在三种不同负荷方式中,斜度跑台测定的ＶＯ２ｍａｘ和ＡＴ要大于平台、功率自行车的值。ＶＯ２ｍａｘ和ＡＴ受运动负荷方式不同的影响。因此,在测定大学生ＶＯ２ｍａｘ和ＡＴ时,应选择斜度跑台进行测定     

Actor diversity and interactions in the development of banana hybrid varieties in Uganda: implications for technology uptake

Purpose: We examine the nature of networks through which new hybrid banana varieties (HBVs) in Uganda are developed, and how different actors engage in the technology development process.

Design/methodology/approach: We collected the data through 20 key informant interviews and 5 focus group discussions with actors involved in the process. We analysed the data with NVivo and Social Network Analysis software.

Findings: The process of developing HBVs involves many actors with a diversity of roles and interests. The network density was 29.4, implying existence of only 29.4% of the possible direct linkages. Strong ties mainly existed among research-oriented actors, with other actors in the periphery.

Practical implications: The current position of smallholder farmers and other non-research actors inhibits their influence on decisions in the technology development process. We recommend that smallholder farmers should be empowered through better organization so that they can influence the process of developing HBVs. Researchers, supported with appropriate policies, should engage more with actors in the intermediary, enterprise and support service domains for a more vibrant agricultural research system.

Theoretical implications: Application of the systems approach to technology development requires a dynamic process that supports involvement of a diverse range of actors. However, close attention to context is important in dealing with issues of power asymmetries and determining to what extent various actors engage in the process.

Originality/value: This work contributes to literature on systems approaches to agricultural and rural development. The paper demonstrates that actor diversity and interactions are critical in technology development and uptake.