肌肽的生物学功能及其在运动实践中的应用展望

查阅近年来大量国内外相关文献,对肌肽的理化性质、分布与代谢、生物学功能等方面进行综述。探讨肌肽保护细胞的途径和机制以及对运动机体的作用,旨在对肌肽这种天然高效、无毒易吸收的抗氧化剂在运动实践中的应用做展望。     

Myosin heavy chain isoform composition in the deltoid and vastus lateralis muscles of elite handball players

ABSTRACT

The purpose of the present study was to compare the myosin heavy chain (MHC) isoform composition of the deltoid and vastus lateralis muscles of the dominant and non-dominant limbs in handball players. Eleven male Greek elite handball players (age 22.6 ± 1.9 yrs, training experience 10.6 ± 2.1 yrs, height 184.1 ± 4.1 cm, and weight 81.0 ± 12.5 kg) participated in the study. Four muscle biopsies were obtained from the dominant and non-dominant deltoid and vastus lateralis muscles during the in-season period. The MHC composition was determined using SDS-PAGE. No significant difference was found between the dominant and non-dominant muscles; Deltoid muscle: MHC I [(95%CI = ?1.22, 0.33), P = 0.228], MHC ΙΙa [(95%CI = ?0.32, 1.59), P = 0.168] and MHC IIx [(95%CI = ?1.49, 1.10), P = 0.749]; Vastus lateralis muscle: MHC I [(95%CI = ?0.38, 0.63), P = 0.586], MHC ΙΙa [(95%CI = ?0.50, 0.65), P = 0.783] and MHC IIx [(95%CI = ?1.08, 0.42), P = 0.355]. The findings of the present study indicate that the greater use of the dominant limbs for throwing actions and body movements in handball do not lead to altered MHC isoform composition compared to the non-dominant limbs.     

Indirect evidence of human skeletal muscle damage and collagen breakdown after eccentric muscle actions

Indirect markers of muscle damage and collagen breakdown were recorded for up to 9 days after a bout of concentric, followed by a bout of eccentric, muscle actions. Nine untrained participants performed two bouts of 50 maximum effort repetitions on an isokinetic dynamometer (angular velocity 1.05 rad.s-1, range of motion 1.75 rad). An initial concentric bout of muscle actions was followed by an eccentric bout 21 days later, using the same knee extensors. Concentric actions induced no changes in maximum voluntary isometric contraction force (MVC),nor induced any changes in the serum enzyme activities of creatine kinase, a lactate dehydrogenase isoenzyme (LDH-1), or alkaline phosphatase. Similarly, concentric actions induced no change in markers of collagen breakdown,namely plasma hydroxyproline and serum type 1 collagen concentration.In contrast,eccentric actions induced a 23.5 ± 19.0% (mean ± s) decrease in MVC immediately post-exercise (P< 0.05), and increased the serum enzyme activities of creatine kinase and LDH-1 to 486 ± 792 and 90 ± 11 IU.l-1 respectively on day 3 post-exercise, and to 189 ± 159 and 96 ±13 IU.l-1 respectively on day 7 post-exercise (all P < 0.05). Eccentric actions induced no significant changes in plasma hydroxyproline, but increased collagen concentration on days 1 and 9 post-exercise (48.6% and 44.3% increases above pre-exercise on days 1 and 9 respectively; both P < 0.05). We conclude that eccentric but not concentric actions may result in temporary muscle damage, and that collagen breakdown may also be affected by eccentric actions. With caution, indices of collagen breakdown may be used to identify exercise-induced damage to connective tissue.     

Effect of individualized resistance training prescription with heart rate variability on individual muscle hypertrophy and strength responses

Abstract

The aim of the present study was to investigate if resistance training (RT), performed with individualized recovery between sessions (RT-IND), promotes greater gains in strength and muscle mass and reduces the variability on adaptations compared to RT with fixed recovery intervals (RT-FIX). Twenty young men (age 21.9?±?3.3 years) were randomized in the RT-IND and RT-FIX groups. Five days before the beginning of the training, measurements of the root mean square of successive R-R intervals differences (RMSSD) values of each individual were performed to establish the baseline values. Before each RT session, the RMSSD values determined whether the participants from RT-IND protocol were recovered from the previous session. Participants performed the RT session only if RMSSD values had returned to the baseline, otherwise they had to wait for an additional 24?h. RT-FIX performed an RT session every 48?h. Muscle strength was measured by one-maximal repetition (1-RM) test and muscle cross-section area (CSA) of the vastus laterals by ultrasonography were assessed pre- and post-training. 1-RM values increased significantly from pre to post-training for both groups (RT-IND: 30% and RT-FIX: 42%, main time effect, P?<?0001), with no significant difference between groups. Muscle CSA increased significantly from pre to post-training (RT-IND: 15.7% and RT-FIX: 15.8%, main time effect, P?<?0001), with no significant difference between groups. In conclusion, RT-IND did not increase the gains in muscle strength and mass neither reduce the variability in muscle adaptations when compared to the RT-FIX.     

Mechanical and EMG responses of the vastus lateralis and changes in biochemical variables to isokinetic exercise in endurance and power athletes

Twelve endurance athletes and six power athletes performed fatiguing isokinetic knee flexions/extensions. Isokinetic torque was recorded during the exercise. Isometric torque, cortisol and lactate responses, electromyographic (EMG) mean power frequency, average rectified value, and conduction velocity were analysed before and after the isokinetic exercise to determine correlations between electrophysiological variables and mechanical performances and/or blood concentrations of biomarkers in the two groups of athletes. The EMG variables were estimated from signals recorded from the vastus lateralis in both voluntary and electrically elicited isometric contractions. Power athletes recorded higher values than endurance athletes for the following variables: pre-exercise isometric maximal voluntary contraction (MVC), isokinetic MVC, rate of mechanical fatigue during isokinetic contractions, pre - post exercise variations and recovery times of conduction velocity and mean power frequency, and lactate concentrations. Moreover, conduction velocity overshooting was observed in endurance athletes during the recovery phase after exercise. The correlation analyses showed that the higher the rate of mechanical fatigue, the higher the lactate production and the reduction in conduction velocity due to the exercise.     

ATP and phosphocreatine utilization in single human muscle fibres during the development of maximal power output at elevated muscle temperatures

In this study, we examined the effect of muscle temperature (Tm) on adenosine triphosphate (ATP) and phosphocreatine utilization in single muscle fibres during the development of maximal power output in humans. Six male participants performed a 6-s maximal sprint on a friction-braked cycle ergometer under both normal (Tm = 34.3 degrees C, s = 0.6) and elevated (T(m) = 37.3 degrees C, s = 0.2) muscle temperature conditions. During the elevated condition, muscle temperature of the legs was raised, passively, by hot water immersion followed by wrapping in electrically heated blankets. Muscle biopsies were taken from the vastus lateralis before and immediately after exercise. Freeze-dried single fibres were dissected, characterized according to myosin heavy chain composition, and analysed for ATP and phosphocreatine content. Single fibres were classified as: type I, IIA, IIAX25 (1 - 25% IIX isoform), IIAX50 (26 - 50% IIX), IIAX75 (51 - 75% IIX), or IIAX100 (76 - 100% IIX). Maximal power output and pedal rate were both greater (P < 0.05) during the elevated condition by 258 W (s = 110) and 22 rev . min(-1) (s = 6), respectively. In both conditions, phosphocreatine content decreased significantly in all fibre types, with a greater decrease during the elevated condition in type IIA fibres (P < 0.01). Adenosine triphosphate content was also reduced to a greater (P < 0.01) extent in type IIA fibres during the elevated condition. The results of the present study indicate that after passive elevation of muscle temperature, there was a greater decrease in ATP and phosphocreatine content in type IIA fibres than in the normal trial, which contributed to the higher maximal power output.     

Normal training response in skeletal muscle of post-infarction heart failure patients

Abstract

Congestive heart failure (CHF) patients experience reduced muscle fatigue resistance and exercise capacity. The aim of this study was to assess whether skeletal muscle in CHF patients has a normal training response compared to healthy subjects. We compared the effect of one-legged knee extensor (1-KE) endurance training in CHF patients (n=10), patients with coronary artery disease (CAD, n=9) and healthy subjects (n=13). The training response was evaluated by comparing trained leg and control leg after the training period. The fall in peak torque during 75 maximal 1-KE isokinetic contractions revealed that CHF patients were less fatigue resistant than healthy subjects in the control leg, but not in the trained leg. Peak power and peak oxygen uptake during dynamic 1-KE exercise was ~10–16% higher in trained leg than control leg. This training response was not significant different between groups. Muscle biopsies of vastus lateralis showed that fibre type composition was not different between trained leg and control leg. Capillary density was 6.5% higher in trained leg than control leg when all groups were pooled. In conclusion, the more fatigable skeletal muscle of CHF patients responds equally to endurance training compared to skeletal muscle of CAD patients and healthy subjects.     

Impact of an acute bout of vibration on muscle contractile properties,creatine kinase and lactate dehydrogenase response

Abstract

The aim of this study was to assess the effects of a bout of whole body vibration (WBV) on muscle response and to determine whether this stimulus leads to muscle damage. Thirty healthy and physically active participants (mean±SD; age: 21.8±2.0 years; height: 176.7±5.8 cm; body mass: 76±6.8 kg and BMI: 23.1±3.7 kg·m^?2) participated in this study. Participants were randomly allocated in one of two groups, one of them performed a bout of 360 s WBV (frequency: 30 Hz; peak-to-peak displacement: 4 mm) (VIB) and the other one adopted a sham position (CON). Muscle contractile properties were analysed in the rectus femoris (RF) by using tensiomyography (TMG) 2 min before the warm-up and 2 min after intervention. Muscle damage was assessed by determining plasma creatine kinase (CK) and lactate dehydrogenase (LDH) levels at three time points; 5 min before warm-up and 1 h and 48 h after the intervention. TMG results showed a significant decrease in maximal displacement (p<0.05) and delay time (p<0.05) in VIB and in delay time (p<0.05) and relaxation time (p<0.05) in CON. Muscle damage markers showed significant group differences (p<0.05) for CK 1 h after the intervention. In addition, differences for CK 1 h after the intervention from baseline (p<0.05) were also observed in VIB. In conclusion, a 6-min bout of WBV results in an increase of muscle stiffness in RF and increased CK levels 1 h after intervention (returning to baseline within 48 h).     

Effect of stride length manipulation on symptoms of exercise-induced muscle damage and the repeated bout effect

This study assessed the effects of stride length on symptoms of exercise-induced muscle damage after downhill running and whether the extent of the symptoms sustained in a repeated bout of downhill running are influenced by stride length manipulation in the first bout. Eighteen males aged 21.1 - 0.6 years (mean - s) were allocated to one of three groups for bout one: preferred stride frequency, overstride and understride. Bout two was performed 2 weeks later at the participants' preferred stride frequency. Maximal isometric force and perceived muscle soreness were assessed pre-test and 30 min, 24, 48 and 72 h post-exercise for each downhill run. Threefactor analyses of variance with repeated measures on time and bout were used for analysis. Results revealed a three-way interaction for soreness (F 8,60 = 3.56, P ? 0.05) and relative isometric strength (F 5.0,37.8 = 3.2, P ? 0.05). Post-hoc analyses revealed that, after bout one, the overstride group perceived most soreness and the understride group retained most strength. After the second bout, the overstride and preferred stride frequency groups perceived less soreness than the preferred stride frequency group in bout one. Strength retention was greater after bout two for all groups. In conclusion, strength retention after a repeated bout appears to be independent of the damage experienced in the initial bout of downhill running. However, understriding may provide least protection against soreness in a subsequent bout.     

Bone mass,bone mineral density and muscle mass in professional golfers

The aim of this study was to determine the effects of long-term professional golf participation on whole-body and regional bone mass and density. Dual-energy X-ray absorptiometry was performed on 15 male professional golfers and 18 sedentary individuals, matched for sex, race, age (29 ± and 25 ± 1 years, respectively), body mass (79 ± 2 and 74 ± 2 kg), height (1.78 ± 0.01 and 1.77 ± 0.02 m) and percent body fat (20 ± 2 and 21 ± 2%; mean ± s _χ). We found that long-term professional golf participation is not associated with significant increments in regional or whole-body bone mass or density. Neither the lumbar spine nor the femoral neck showed any noticeable enhancement of bone mass in professional golfers compared with controls from the same population. The only effect of professional golf participation on regional body composition was a 9% increase in muscle mass in the dominant arm (P ? 0.05).     

优秀男子手枪运动员上肢关节屈伸肌群等速肌力测试研究

通过录像观察法、实验测试法,利用德国Isomed 2000等速力量测试系统对男子速射和男子慢射运动员右侧肩关节、肘关节、腕关节依次进行角速度为60°/s等速向心肌肉力量测试,选取屈肌肌群、伸肌肌群的相对峰力矩和相对峰值功率为指标,对手枪男子速射和慢射项目运动员的上肢肌肉力量进行了研究,比较分析了男子速射和男子慢射肩、肘、腕关节屈伸肌群的肌力特征。发现肘关节伸肌肌群、腕关节屈肌肌群分别为速射和慢射影响最大的关节肌群。     

The effect of exercise-induced muscle damage on isometric and dynamic knee extensor strength and vertical jump performance

In this study, we assessed the effect of exercise-induced muscle damage on knee extensor muscle strength during isometric, concentric and eccentric actions at 1.57 rad · s -1 and vertical jump performance under conditions of squat jump, countermovement jump and drop jump. The eight participants (5 males, 3 females) were aged 29.5 - 7.1 years (mean - s ). These variables, together with plasma creatine kinase (CK), were measured before, 1 h after and 1, 2, 3, 4 and 7 days after a bout of muscle damaging exercise: 100 barbell squats (10 sets 2 10 repetitions at 70% body mass load). Strength was reduced for 4 days ( P ? 0.05) but no significant differences ( P > 0.05) were apparent in the magnitude or rate of recovery of strength between isometric, concentric and eccentric muscle actions. The overall decline in vertical jump performance was dependent on jump method: squat jump performance was affected to a greater extent than countermovement (91.6 - 1.1% vs 95.2 - 1.3% of pre-exercise values, P ? 0.05) and drop jump (95.2 - 1.4%, P ? 0.05) performance. Creatine kinase was elevated ( P ? 0.05) above baseline 1 h after exercise, peaked on day 1 and remained significantly elevated on days 2 and 3. Strength loss after exercise-induced muscle damage was independent of the muscle action being performed. However, the impairment of muscle function was attenuated when the stretch-shortening cycle was used in vertical jumping performance.     

牛磺酸和／或递增负荷训练对大鼠骨骼肌不同肌纤维线粒体Ca^2＋-ATP酶活性的影响

以大鼠力竭性运动为模型，观察了牛磺酸和／或递增负荷训练对大鼠力竭运动后即刻红、白肌线粒体Ca^2 -ATP酶活性的影响。结果显示：1)安静时白肌纤维线粒体Ca^2 -ATP酶活性较红肌的高；2)力竭运动使白肌纤维线粒体Ca^2 -ATP酶活性降低，红肌的则升高；3)5周递增负荷训练对白肌纤维线粒体Ca^2 -ATP酶活性影响较大，而对红肌的几乎没有什么影响；4)牛磺酸能使力竭运动后白肌和红肌张维线粒体Ca^2 -ATP酶活性升高，结合训练其作用更明显。结果提示：递增负荷训练中慢运动单位可能较少参与运动，所以该方法可能只对白肌起到积极的锻炼作用，牛磺酸和／或训练有保护白肌和红肌线粒体的功能和防止红肌线粒体功能损伤的作用。     

A bioengineering analysis of human muscle and joint forces in the lower limbs during running

A two-dimensional, dynamic bioengineering model of the lower limbs was developed in order to estimate muscle and joint forces present during running at 4.5 m s-1. Data were collected from four subjects using a force platform and cine film. Individual X-rays and anthropometric data from the lower limbs were utilized to produce accurate bone models of the subjects' legs. Electromyographic verification of the model was undertaken while a runner was undergoing treadmill running at 4.5 m s-1. Results indicate that peak muscle forces of 22 times subject body weight (22 BW) could be present in the quadriceps muscle group and 7 BW in the gastrocnemius. The anterior shin muscles were found to be active for the first 9% of stance phase only, and compressive loads of 33 BW were found in the knee joint. The relationship between these high forces in the lower limbs and running related injuries is discussed.     

青少年中长跑训练后疲劳消除的方法与措施

青少年运动员中长跑大运动量训练后,增加了负荷,并加深加重了机体的疲劳.本文是以文献资料为基础,结合教学训练中的实际情况,分析了中长跑训练后肌肉疲劳和神经系统疲劳两大主要因素并对其恢复的手段及措施进行了探讨.     

《体育与健康》课中武术教学内容与方法的研究

在对学生的学习兴趣及自身条件进行分析的基础上,提出在《体育与健康》课中武术的教学内容与方法:培养学生学习武术的兴趣;对学生进行素质教育;在武术教学中融入健康教育;培养学生的创新素质。以期在教学内容与方法上达到《课程标准》的教学要求。     

高等师范院校公共体育课教学课程内容与结构的改革

教学内容体系与课程设置结构的改革是教学整体改革的关键，原有的教学体系已不适应时代发展的需要。新的体育教学内容与结构应从培养高素质的体育复合型人才的大局出发，使知识、技术、技能的培养与娱乐、审美、品德教育紧密结合，以形成育人的科学化新体系。     

牛磺酸对疲劳运动大鼠心肌线粒体脂质过氧化水平及GSH含量的影响

为探讨牛磺酸对运动机体的作用,本研究以力竭游泳大鼠为运动疲劳模型,观察了牛磺酸对心肌线粒体中ＭＤＡ及ＧＳＨ含量的影响。结果表明,牛横酸有显著抑制疲劳运动条件下心肌线粒体脂质过氧化水平及提高ＧＳＨ含量的作用。这可能是其线粒体膜保护机制之一。     

Effects of plyometric training on maximal-intensity exercise and endurance in male and female soccer players

In a randomised controlled trial design, effects of 6 weeks of plyometric training on maximal-intensity exercise and endurance performance were compared in male and female soccer players. Young (age 21.1 ± 2.7 years) players with similar training load and competitive background were assigned to training (women, n = 19; men, n = 21) and control (women, n = 19; men, n = 21) groups. Players were evaluated for lower- and upper-body maximal-intensity exercise, 30 m sprint, change of direction speed and endurance performance before and after 6 weeks of training. After intervention, the control groups did not change, whereas both training groups improved jumps (effect size (ES) = 0.35–1.76), throwing (ES = 0.62–0.78), sprint (ES = 0.86–1.44), change of direction speed (ES = 0.46–0.85) and endurance performance (ES = 0.42–0.62). There were no differences in performance improvements between the plyometric training groups. Both plyometric groups improved more in all performance tests than the controls. The results suggest that adaptations to plyometric training do not differ between men and women.