Is physical activity a part of who I am? A review and meta-analysis of identity,schema and physical activity

Two parallel literatures on the physical activity (PA) identity and schema constructs have the potential to supplement traditional social cognitive approaches used for PA promotion. The purpose of this paper was to review schema/identity research and appraise its relationship with PA via meta-analysis followed by thematic analyses of its correlates, as well as its proposed mechanisms on PA. Eligible studies were from English, peer-reviewed published articles that examined identity and/or schema in the context of PA. Searches were completed in June 2015 in five databases. Sixty-two independent data-sets (32 available for meta-analysis), primarily of modest quality, were identified. Results of the random effects meta-analysis showed that the point-estimate between identity/schema and behaviour was r?=?.44 (CI?=?.39?.48), and invariant to selected study characteristics. Thematic review showed that identity/schema was associated with commitment, ability, affective judgments, identified/integrated regulation and social comparison and predicted intention, self-regulatory efficacy, and self-regulation strategy use. It had reliable evidence as a moderator of the intention–behavior relationship, was associated with increases in the speed of processing of relevant information and created negative affect under hypothetical identity–behavior discrepant situations. While this initial research is promising, more rigorous research designs, including interventions to increase identity/schema, are warranted.     

基于腹腔镜手术训练的眼动特征研究

在腹腔镜模拟训练过程中,研究不同训练模式下被测试者的注视策略,探索腹腔镜训练的新模式。被测试者被随机分为无指导组,视频学习组和专家指导组进行左右移环任务。利用Tobii X1 Light型眼动仪调用模拟训练箱中的摄像头,采集受试者的眼动数据。通过对数据处理分析,计算注视点个数,平均注视时间,注视时间百分比,扫描距离指标。与对照组相比,视频学习和专家指导模式下,任务完成时间降低23%,扫描距离缩短25%,注视点个数减少17%,平均注视时间没有显著差异。视频组和专家指导组之间无明显差异。结果表明不同学习模式下,被测试者的注视行为有明显差异。视频学习和专家指导下效果更好,可以用专家操作时的注视点视频指导初级训练者进行训练。     

Individual factors and physical work load in relation to sensory thresholds in a middle-aged general population sample

The aim of this study was to explore individual and occupational factors possibly related to sensory thresholds in 484 middle-aged men and women from the general population. Multivariate analyses were performed using a linear model including eight covariates (age, body height, skin temperature, smoking habits, musculoskeletal symptoms during the last week before examination, isometric muscle strength, aerobic capacity, and average physical work load during the last 15 years). Men and women were considered separately in all analyses. Major findings were as follows: pressure pain thresholds increased with muscle strength; cold perception thresholds on the foot improved with increasing skin temperature; vibration and warm perception thresholds on the foot increased with age and body height; pressure pain threshold on the leg was decreased and vibration threshold on the hand was increased in women with musculoskeletal symptoms; pressure pain thresholds were slightly increased in men reporting long-lasting high physical work load. Significant sex differences were found for the majority of sensory thresholds, that is higher thresholds in men. However, body height was found to be more important than gender for differences in vibration and warm perception thresholds on the foot. Electronic Publication     

Cross education of muscular strength during unilateral resistance training and detraining

Abstract. The purpose of the present study was to examine the changes in maximum voluntary isometric contraction (MVC) in the contralateral untrained limb during unilateral resistance training and detraining, and to examine the factors inducing these changes by means of electrophysiological techniques. Nine healthy males trained their plantar flexor muscles unilaterally 4 days·week^–1 for 6 weeks using 3 sets of 10–12 repetitions at 70–75% of one-repetition maximum a day, and detrained for 6 weeks. Progressive unilateral resistance training significantly (P<0.05) increased MVC, integrated electromyogram (iEMG), and voluntary activation in the trained and contralateral untrained limbs. The changes in MVC after training were significantly correlated with the changes in iEMG in both limbs. No significant changes occurred in MVC, voluntary activation, and iEMG in the contralateral limb after detraining. The changes in MVC after detraining did not correlate with the changes in voluntary activation or iEMG in either limb. Training and detraining did not alter twitch and tetanic peak torques in either limb. These results suggest that the mechanisms underlying cross education of muscular strength may be explained by central neural factors during training, but not solely so during detraining. Electronic Publication     

神经肌肉电刺激模拟肌肉力量训练的生物力学研究

基于对电刺激模拟肌肉力量训练的理论与实践研究，结果表明：神经肌肉电刺激（NMES）的训练效果显著优于肌肉直接电刺激（MES），肌肉力量素质的增长与电刺激方式和刺激源的电特性有关；NMES能以较低的体能消耗完成肌肉力量的训练，适合作为常规训练前，中、后的辅助训练手段，NMES模拟肌肉力量训练的方式能满足肌肉功能群协调能力的同步发展。     

健康体检人群空腹血糖、糖化血红蛋白联合检测的应用研究

目的 分析空腹血糖、糖化血红蛋白联合检测在健康体检中的应用价值.方法 选择北京市海淀医院437名健康体检者作为研究对象,分别检测其空腹血糖、糖化血红蛋白水平,并对二者的相关性进行分析.结果 437名研究对象中,糖化血红蛋白＜5.5％者139例,5.5％ ～6.5％者257例,＞6.5％者41例.糖化血红蛋白＞6.5％者的空腹血糖水平均明显高于＜5.5％、5.5％ ～6.5％者(P＜0.01).相关分析显示,437名体检者的糖化血红蛋白水平与空腹血糖水平之间呈正相关(P＜0.01).结论 健康人群空腹血糖、糖化血红蛋白联合检测对糖尿病的筛查具有重要价值,适合在健康人群体检中推广.     

The relationship of age and cardiovascular fitness to cognitive and motor processes

Older and younger aerobically trained and sedentary adults participated in an S1-S2-S3 paradigm designed to elicit event-related potential (ERP) and behavioral responses to determine the influence of cardiovascular fitness on cognitive and motor processes. The paradigm provided warning (S1) as to the difficulty level of an upcoming decision task (S2). Participants had to decide the taller of two bars on presentation of S2 but hold their response until S3, to which they indicated their choice motorically. Results revealed age-related differences for ERP measures as older participants showed increased amplitude of the stimulus preceding negativity (SPN) prior to S2, and longer latencies and equipotentiality of P3 in response to S2. Fitness effects were also observed for the contingent negative variation (CNV) with decreased amplitude for fit relative to sedentary individuals. Age interacted with fitness for P3 latency to S2 as older sedentary individuals showed the longest latency followed by older fit and both younger groups. No significant group differences were observed for reaction time (RT) to S3. Therefore, physical fitness is associated with attenuation of cognitive decline in older individuals and greater economy of motor preparation for both young and older participants.     

Effects of voluntary wheel running and amino acid supplementation on skeletal muscle of mice

The aims of the present study were as follows: (1) to examine the adaptational changes to chronic endurance voluntary exercise and (2) to investigate the effects of amino acid supplementation on the adaptational changes induced by endurance training in hindlimb (gastrocnemius, tibialis, soleus) and respiratory (diaphragm) muscles of mice. Male C57Bl6 mice were divided in four groups: control sedentary, sedentary supplemented with amino acid mixture (BigOne, 1.5 mg g day^–1 in drinking water for 8 weeks), running (free access to running wheels for 8 weeks), and running supplemented with amino acid mixture. Myosin heavy chain (MHC) isoform distribution was determined in all muscles considered. Fiber cross-sectional area (CSA) was measured in the soleus muscle. In all muscles except the tibialis, endurance training was associated with an overall shift towards the expression of slower MHC isoforms. Amino acid supplementation produced a shift towards the expression of faster MHC isoforms in the soleus and diaphragm muscles, and partially antagonized the effects of training. Immunohistochemical analysis of CSA of individual muscle fibers from the soleus muscle suggests that voluntary running produced a decrease in the size of type 1 fibers, and amino acid supplementation during training resulted in an increase in size in both type 1 and type 2A fibers. Collectively, these results suggest that the endurance adaptations induced by voluntary running depend on the muscle type, and that amino acid supplementation is able to modulate both fiber size and MHC isoform composition of skeletal muscles in sedentary and exercised mice.     

Estimating relative physical workload using heart rate monitoring: a validation by whole-body indirect calorimetry

Measuring physical workload in occupational medicine is fundamental for risk prevention. An indirect measurement of total and relative energy expenditure (EE) from heart rate (HR) is widely used but it has never been validated. The aim of this study was to validate this HR-estimated energy expenditure (HREEE) method against whole-body indirect calorimetry. Twenty-four-hour HR and EE values were recorded continuously in a calorimetric chambers for 52 adult males and females (19–65 years). An 8-h working period was retained, comprising several exercise sessions on a cycloergometer at intensities up to 65% of the peak rate of oxygen uptake. HREEE was calculated with reference to cardiac reserve. A corrected HREEE (CHREEE) was also calculated with a modification to the lowest value of cardiac reserve. Both values were further compared to established methods: the flex-HR method, and the use of a 3rd order polynomial relationship to estimate total and relative EE. No significant difference was found in total EE when measured in a calorimetric chamber or estimated from CHREEE for the working period. A perfect linear and identity relationship was found between CHREEE and energy reserve values for intensities ranging from 15% to 65%. Relative physical workload can be accurately assessed from HR recordings when expressed in CHREEE between 15% to 65%, and EE can be accurately estimated using the CHREEE method.     

Muscle strength, volume and activation following 12-month resistance training in 70-year-old males

In elderly males muscle plantar flexor maximal voluntary contraction (MVC) torque normalised to muscle volume (MVC/VOL) is reduced compared to young males as a result of incomplete muscle activation in the elderly. The aim of the present study was to determine the influence of a 12-month resistance training programme on muscle volume, strength, MVC/VOL, agonist activation and antagonist coactivation of the plantarfexors in elderly males. Thirteen elderly males aged 70 years and over (range 70–82 years), completed a 12-month whole body resistance-training programme (TRN), training three times a week. Another eight males (range 18–30 years), who maintained their habitual physical activity for the same 12-month period as the TRN group acted as controls (CTRL). Isometric plantarflexor maximal voluntary contraction (MVC) torque increased in the TRN group by 20% (P<0.01), from 113.1±22.0 Nm to 141.5±19.2 Nm. Triceps surae volume (TS VOL) assessed using MRI, increased by 12%, from 796.3±78.9 cm³ to 916.8±144.4 cm³ . PF activation, measured using supramaximal double twitch interpolation, increased from 83.6±11.0% pre training, to 92.1±7.6% post training (P<0.05). Dorsiflexion MVC and antagonist coactivation (assessed using surface electromyography) did not change with training. Plantarflexor MVC torque normalized for triceps surae muscle volume (MVC/VOL) was 142.6±32.4 kN m^–2 before training and 157.0± 27.9 kN m^–2 after training (a non-significant increase of 8%). No significant change in any measurement was observed in the CTRL group. This study has shown that the gain in muscle strength in response to long-term (12-month) training in older men is mostly accounted for by an increased muscle volume and activation.