瑜伽对田径运动员运动性疲劳恢复的可行性分析

本文使用文献资料法、综述法、比较法、逻辑分析法等科研方法,针对瑜伽对心理和生理功能的作用和运动员的运动性疲劳两方面进行综述对照研究,探究得出:将瑜伽放松练习运用于田径运动员运动性疲劳恢复中的意义,并且提出将瑜伽练习运用于田径运动员的运动性疲劳恢复训练当中。     

运动性疲劳产生的机制及其消除途径

通过文献资料，从生理生化角度，对运动性疲劳的定义、产生机制及其消除途径进行了综述，为全面系统地认识运动性疲劳产生的机制提供了有效的途径．同时筛选出一些对消除运动性疲劳较为有效的手段和方法，以供参考讨论。     

Corticospinal changes induced by fatiguing eccentric versus concentric exercise

The present study assessed neuromuscular and corticospinal changes during and after a fatiguing submaximal exercise of the knee extensors in different modes of muscle contraction. Twelve subjects performed two knee extensors exercises in a concentric or eccentric mode, at the same torque and with a similar total impulse. Exercises consisted of 10 sets of 10 repetitions at an intensity of 80% of the maximal voluntary isometric contraction torque (MVIC). MVIC, maximal voluntary activation level (VAL) and responses of electrically evoked contractions of the knee extensors were assessed before and after exercise. Motor evoked potential amplitude (MEP) and cortical silent period (CSP) of the vastus medialis (VM) and rectus femoris (RF) muscles were assessed before, during and after exercise. Similar reductions of the MVIC (?13%), VAL (?12%) and a decrease in the peak twitch (?12%) were observed after both exercises. For both VM and RF muscles, MEP amplitude remained unchanged during either concentric or eccentric exercises. No change of the MEP amplitude input–output curves was observed post-exercise. For the RF muscle, CSP increased during the concentric exercise and remained lengthened after this exercise. For the VM muscle, CSP was reduced after the eccentric exercise only. For a similar amount of total impulse, concentric and eccentric knee extensor contractions led to similar exercise-induced neuromuscular response changes. For the two muscles investigated, no modulation of corticospinal excitability was observed during or after either concentric or eccentric exercises. However, intracortical inhibition showed significant modulations during and after exercise.     

Physiological responses in different intensities of resistance exercise – Critical load and the effects of aging process

Aim was to identify critical load (CL) in young and elderly apparently healthy male cohorts. To contrast the metabolic, cardiovascular and perceptual responses on CL according to age. We evaluated 12 young (23 ± 3 years) and 10 elderly (70 ± 2 years) apparently healthy active males, who underwent: (1) 1 repetition maximum (1RM) test on a 45° Leg Press; (2) on different days, three high-intensity resistance exercise constant load tests (60%, 75% and 90% 1RM) until fatigue (Tlim). Absolute values of both the CL asymptote and curvature constant (kg) were significantly lower in elderly subjects (P < 0.05). In contrast, elderly subjects demonstrated a significantly higher number of repetitions at CL when compared with young subjects (P < 0.05). As expected, oxygen uptake (VO₂) and heart rate (HR) during maximal aerobic exercise testing were significantly reduced in older subjects. However, percent-predicted aerobic capacity were higher in older subjects (P < 0.05). In addition, blood lactate ([La^?]) corrected to Tlim and rating of perceived exertion values were greater in younger subjects at all intensities (P < 0.05). These findings, despite reduced force production in older subjects, endurance-related parameters are well preserved according to age-adjusted percent-predicted values in apparently healthy males.     

The impact of physiological load on anticipation skills in badminton: From testing to training

Research remains unclear on the impact of physiological load on perceptual-cognitive skills in sport. Moreover, no study has examined the training of perceptual-cognitive skills under physiological load. The current study comprised two phases. Firstly, we examined the impact of badminton-specific physiological load on anticipatory skills in expert badminton players (n = 13), including key underlying mechanisms, such as gaze behaviour. Under high physiological load, participants displayed less efficient visual search behaviour and showed a reduction in response accuracy. Secondly, we examined the effects of combining perceptual-cognitive simulation training with the high physiological load. Ten of the expert badminton players were assigned to a combined training group, where the simulation training and the physiological load intervention occurred simultaneously or an independent training group, whereby the two components were completed independently. The combined training group showed a positive change in the efficiency of their visual search behaviours compared to the independent training group, but no significant performance improvements were found. Overall, findings demonstrate that high physiological load is detrimental to experts’ anticipatory skills. However, combining perceptual-cognitive simulation training with high physiological load can potentially negate these debilitating effects.     

Effect of a Brazilian Jiu-jitsu-simulated tournament on strength parameters and perceptual responses

This study aimed to analyse the effects of a simulated Brazilian jiu-jitsu (BJJ) tournament on vertical jump performance, grip strength test and perceived effort responses. 22 male BJJ athletes participated in a simulated tournament consisting of three 7 min matches separated by 14 min of rest. Kimono grip strength test (KGST), counter movement jump (CMJ) and rate of perceived exertion (RPE) were measured before and after each match, while RPE of specific areas was assessed after three matches. ANOVA for repeated measures was used to compare strength parameters after each match with the level of significance set at 5%. The key results showed a significant decrease of jump height (p = 0.001) and net vertical impulse in the CMJ (p = 0.031), as well as a reduction of the number of reps in the KGST (p < 0.001). A significant increase of RPE was found throughout the matches (p < 0.001). Considering the RPE in specific areas, no differences were observed between the upper and lower body (p = 0.743). We conclude that the BJJ simulated tournament generated a decrease of performance in both upper and lower limbs and provoked a progressive increase in the effort perception over the matches.     

Tribute to Dr Jacques Rogge: muscle activity and fatigue during hiking in Olympic dinghy sailing

‘A tribute to Dr J. Rogge’ aims to systematically review muscle activity and muscle fatigue during sustained submaximal quasi-isometric knee extension exercise (hiking) related to Olympic dinghy sailing as a tribute to Dr Rogge’s merits in the world of sports. Dr Jacques Rogge is not only the former President of the International Olympic Committee, he was also an orthopaedic surgeon and a keen sailor, competing at three Olympic Games. In 1972, in fulfilment of the requirements for the degree of Master in Sports Medicine, he was the first who studied a sailors’ muscle activity by means of invasive needle electromyography (EMG) during a specific sailing technique (hiking) on a self-constructed sailing ergometer. Hiking is a bilateral and multi-joint submaximal quasi-isometric movement which dinghy sailors use to optimize boat speed and to prevent the boat from capsizing. Large stresses are generated in the anterior muscles that cross the knee and hip joint, mainly employing the quadriceps at an intensity of 30–40% maximal voluntary contraction (MVC), sometimes exceeding 100% MVC. Better sailing level is partially determined by a lower rate of neuromuscular fatigue during hiking and for ≈60% predicted by a higher maximal isometric quadriceps strength. Although useful in exercise testing, prediction of hiking endurance capacity based on the changes in surface EMG in thigh and trunk muscles during a hiking maintenance task is not reliable. This could probably be explained by the varying exercise intensity and joint angles, and the great number of muscles and joints involved in hiking.

Highlights

• Dr Jacques Rogge, former president of the International Olympic Committee and Olympic Finn sailor, was the first to study muscle activity during sailing using invasive needle EMG to obtain his Master degree in Sports Medicine at the Ghent University.

• Hiking is a critical bilateral and multi-joint movement during dinghy racing, accounting for >60% of the total upwind leg time. Hiking generates large stresses in the anterior muscles that cross the knee and hip joint.

• Hiking is considered as a quasi-isometric bilateral knee extension exercise. Muscle activity measurements during sailing, recorded by means of EMG, show a mean contraction intensity of 30-40% maximal voluntary contraction with peaks exceeding 100%.

• Hiking performance is strongly related to the development of neuromuscular fatigue in the quadriceps muscle. Since maximal strength is an important determinant of neuromuscular fatigue during hiking, combined strength and endurance training should be incorporated in the training program of dinghy sailors.

     

The effects of short versus long inter-set rest intervals in resistance training on measures of muscle hypertrophy: A systematic review

Although the effects of short versus long inter-set rest intervals in resistance training on measures of muscle hypertrophy have been investigated in several studies, the findings are equivocal and the practical implications remain unclear. In an attempt to provide clarity on the topic, we performed a systematic literature search of PubMed/MEDLINE, Scopus, Web of Science, Cochrane Library, and Physiotherapy Evidence Database (PEDro) electronic databases. Six studies were found to have met the inclusion criteria: (a) an experimental trial published in an English-language peer-reviewed journal; (b) the study compared the use of short (≤60?s) to long (>60?s) inter-set rest intervals in a traditional dynamic resistance exercise using both concentric and eccentric muscle actions, with the only difference in resistance training among groups being the inter-set rest interval duration; (c) at least one method of measuring changes in muscle mass was used in the study; (d) the study lasted for a minimum of four weeks, employed a training frequency of ≥2 resistance training days per week, and (e) used human participants without known chronic disease or injury. Current evidence indicates that both short and long inter-set rest intervals may be useful when training for achieving gains in muscle hypertrophy. Novel findings involving trained participants using measures sensitive to detect changes in muscle hypertrophy suggest a possible advantage for the use of long rest intervals to elicit hypertrophic effects. However, due to the paucity of studies with similar designs, further research is needed to provide a clear differentiation between these two approaches.     

Short-term heat acclimation prior to a multi-day desert ultra-marathon improves physiological and psychological responses without compromising immune status

Multistage, ultra-endurance events in hot, humid conditions necessitate thermal adaptation, often achieved through short term heat acclimation (STHA), to improve performance by reducing thermoregulatory strain and perceptions of heat stress. This study investigated the physiological, perceptual and immunological responses to STHA prior to the Marathon des Sables. Eight athletes (age 42 ± 4 years and body mass 81.9 ± 15.0 kg) completed 4 days of controlled hyperthermia STHA (60 min·day^?1, 45°C and 30% relative humidity). Pre, during and post sessions, physiological and perceptual measures were recorded. Immunological measures were recorded pre-post sessions 1 and 4. STHA improved thermal comfort (P = 0.02), sensation (P = 0.03) and perceived exertion (P = 0.04). A dissociated relationship between perceptual fatigue and T_re was evident after STHA, with reductions in perceived Physical (P = 0.04) and General (P = 0.04) fatigue. Exercising T_re and HR did not change (P > 0.05) however, sweat rate increased 14% (P = 0.02). No changes were found in white blood cell counts or content (P > 0.05). Four days of STHA facilitates effective perceptual adaptations, without compromising immune status prior to an ultra-endurance race in heat stress. A greater physiological strain is required to confer optimal physiological adaptations.     

慢性运动性疲劳状态下心脏心钠素内分泌功能的实验研究

采用递增负荷跑台练习,建立运动性疲劳模型;应用血浆放射免疫测定、免疫组织化学、计算机图像分析等方法,观察慢性运动性疲劳状态下血浆心钠含量及心肌组织心钠素表达的改变.结果表明,慢性运动性疲劳可使心脏心钠素内分泌功能降低,表现为血浆心钠素含量和心肌组织心钠素表达减少,不利于运动应激中心脏内分泌功能的发挥.