Effects of recombinant human erythropoietin injections on physical self in endurance athletes

This study examined the time course of mean self-esteem and physical self scores in three groups: male endurance athletes treated with recombinant human erythropoietin (rHuEPO group, n = 6), a placebo group (n = 5) injected with a sodium chloride solution and a control group who did not receive any injection (n = 6). Each participant completed the Physical Self Inventory twice a day (between 07.00 and 09.00 h and between 19.00 and 21.00 h). Using a 10 cm visual analog scale, the participants assessed global self-esteem, physical self-worth and the sub-domains of physical condition, sport competence, attractive body and physical strength (Fox & Corbin, 1989). This was conducted over three consecutive periods: in the 2 weeks before the course of injections, during the 6 weeks of injections and for 4 weeks after the injections. Aerobic capacity was assessed before and after 4 weeks of treatment. The results showed a significant increase in aerobic physical fitness in the rHuEPO group and a significant increase in perceived physical condition and physical strength scores at the end of treatment. The main psychological result was that endurance athletes were highly sensitive to the effects of rHuEPO on physical fitness. The perception of increased physical condition may lead to a stronger commitment to training. The rHuEPO injections presented a dangerous hedonic effect linked to endurance training. These results confirm the need to tackle rHuEPO abuse at any time during the training season.     

Nitrogen addition delays the emergence of an aridity-induced threshold for plant biomass

Crossing certain aridity thresholds in global drylands can lead to abrupt decays of ecosystem attributes such as plant productivity, potentially causing land degradation and desertification. It is largely unknown,however, whether these thresholds can be altered by other key global change drivers known to affect the water-use efficiency and productivity of vegetation, such as elevated CO₂ and nitrogen(N). Using >5000 empirical measurements of plant biomass, we showed that crossing a...     

Global latitudinal patterns in leaf herbivory are related to variation in climate,rather than phytochemicals or mycorrhizal types

<正>Plant-herbivore interactions are among the most important factors shaping plant community dynamics and ecosystem functioning. The latitudinal herbivory hypothesis proposed that insect herbivory rates decline with increasing latitudes owing to benign environmental conditions in the tropics, but studies have produced contradictory conclusions[1–3].     

体力活动与多发性硬化症研究的10大问题

摘要：全世界约有250万人患有多发硬化症（MS）,并且发病率有增加趋势。MS是一种中枢神经系统疾病,与多种症状和功能障碍相关。目前一线治疗方法对晚期患者基本无效。越来越多的证据表明体力活动（PA）有益于MS患者,但是大多数MS患者存在PA不足和静坐少动行为。因此,我们提出了10个研究问题,旨在指导今后有关PA和MS的研究：1）PA是否是一种MS的缓解性治疗行为？2）PA对MS患者有哪些益处？3）什么样的PA处方最适合MS患者？4）MS患者在PA中有哪些安全问题？5）哪些MS患者可以通过PA获得益处？6）哪些变量可以用来解释PA对MS患者的作用？7）有效促进 MS患者进行PA的行为干预方法是什么？8）我们如何将研究成果用于实际临床工作中？9）静坐少动行为对MS患者有什么影响？10）评价MS患者PA的最佳方法是什么？这些问题对于帮助我们了解PAPA对MS患者长期和短期的效果,开发新方法促进和保持MS患者的PA至关重要,解决这些问题可以大大改善MS患者的生活质量。     

Influences of volitional and forced intentions on physical activity and effort within the theory of planned behaviour

In the present study, we examined the utility of volitional and forced intentions in predicting participation in physical activities and effort within the theory of planned behaviour. Four hundred and forty-four participants (184 males, 260 females) aged 19.1 +/- 3.3 years (mean +/- s) completed self-report measures of intentions, attitudes, subjective norms, perceived behavioural control, volitional intentions, forced intentions, and past behaviour in a physical activity context. Six weeks later, they completed self-report measures of physical activity behaviour and effort. Results indicated that volitional intentions and forced intentions contributed to the prediction of effort over and above intentions, attitudes, subjective norms, perceptions of control, past behaviour, and the product terms of attitudesxintentions and subjective normsxintentions. Volitional intentions and forced intentions did not predict participation in physical activities over and above effort. We concluded that volitional intentions and forced intentions assist in the explanation of effort in the context of physical activity behaviour.     

Exercise makes you feel good, but does feeling good make you exercise?: an examination of obese dieters

Whereas exercise-induced mood enhancement has been well documented, the relationship between mood and exercise participation is less well understood. Mood states influence evaluative judgments that could plausibly influence a decision to exercise. Further, most exercise-mood research is limited to normal weight adults in response to a single exercise session. The current investigation examines the influence of (a) morning mood on exercise, (b) exercise intensity/duration on mood enhancement, and (c) daily change in mood on exercise days compared with nonexercise days in obese behavioral weight loss program (BWLP) participants. Participants (N = 36) recorded morning, evening, and pre-and postexercise mood, as well as the type, duration, and intensity of exercise. Within-person analyses indicated that (a) morning mood was associated with an increased likelihood of exercising, (b) mood ratings were higher following exercise of greater intensity and duration, and (c) daily mood enhancement was associated with greater exercise initiation and greater exercise intensity. Measuring mood before and after exercise may yield important clinical information that can be used to promote physical activity in obese adults.     

A biomechanical comparison of dominant and non-dominant arm throws for speed and accuracy

Training a non-dominant limb may increase a competitor's ability to perform with either side of his or her body and confer an advantage over competitors that use one side of the body exclusively. The aim of this study was to determine the kinematic differences between dominant and non-dominant arm throwing techniques for speed and accuracy in Under-17 and Under-19 high-performance cricketers. Seven participants performed ten throws for each arm (dominant/non-dominant) and condition (speed/accuracy) at a target positioned 10 m in front of them. Three-dimensional kinematic variables were measured using a Vicon motion analysis system. Digital footage was used to calculate stride data, ball speed, and record target accuracy. Data were analysed using repeated-measures analysis of variance and chi-squared tests. The non-dominant arm throws had significantly lower maximum lead knee lift, did not extend the lead knee in the arm acceleration phase, had significantly less elbow flexion before extension, had significantly less shoulder external rotation at the start of the arm acceleration phase, did not have a delay between the initiation of pelvic and upper torso internal rotation, and displayed a less than optimal coordination pattern. A speed-accuracy trade-off existed for the dominant arm throws. No trade-off was identified for the non-dominant arm throws. Through an enhanced understanding of how throwing technique varies between dominant and non-dominant arms, an opportunity exists for a performance-enhancing programme to be implemented so that ambidexterity of the throwing skill can be improved.