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This study investigated whether regular alpine skiing could reverse sarcopenia and muscle weakness in older individuals. Twenty-two older men and women (67 ± 2 years) underwent 12 weeks of recreational skiing, two to three times a week, each session lasting∼3.5 h. An age-matched, inactive group ( n=20, 67 ± 4 years) served as a control (CTRL). Before and after the training period, knee extensors muscle thickness ( T), pennation angle (θ) and fascicle length ( L) of the vastus lateralis muscle were measured by ultrasound. Maximum isokinetic knee extensor torque (MIT) at an angular velocity of 60°/s was measured by dynamometry. After the training, T increased by 7.1% ( P<0.001), L by 5.4% ( P<0.02) and θ by 3.4% ( P<0.05). The increase in T was matched by a significant gain in MIT (13.3%, P<0.001). No significant changes, except for a decrease in θ (2.1%, P<0.02), were found in the CTRL group. The gain in T in the training group correlated significantly with an increase in the focal adhesion kinase content, pointing to a primary role of this mechano-sensitive protein in sarcomere remodeling with muscle hypertrophy. Overall, the results show that alpine skiing is an effective intervention for combating sarcopenia and weakness in old age. [ABSTRACT FROM AUTHOR]

We hypothesized that 12 weeks of downhill skiing mitigates the functional deficits of knee extensor muscles in elderly subjects due to the specific recruitment of fast motor units during forceful turns on the slope. Downhill skiing led to a 1.4-fold increase in the mean cross-sectional area of slow ( P=0.04)- and fast ( P=0.08)-type muscle fibers. Fold changes in the expression of the structural component of focal adhesions, gamma-vinculin, were correlated with alterations in concentric force ( r=0.64). Hypertrophy of fast fibers was more pronounced in women than in men (1.7 vs 1.1). Gender-specific structural-functional adjustments of knee extensor muscles and attached patellar tendon were reflected by altered expression of pro- vs de-adhesive proteins and a number of correlations. The de-adhesive protein tenascin-C was selectively increased in women compared with men (1.7 vs 1.1) while the content of the adhesive collagen XII was specifically reduced in women. The pro-adhesive focal adhesion kinase showed a specific increase in men compared with women (1.9 vs 1.1). Our findings indicate that quantitatively matched adaptations in slow and fast motor units of extensor muscle underlie the preventive effect of skiing against sarcopenia and support that hypertrophy and reinforcement of fiber adhesion operate in the improvement of muscle strength. [ABSTRACT FROM AUTHOR]

To examine the time course of alteration in neural process (spinal loop properties) during prolonged tennis playing, 12 competitive players performed a series of neuromuscular tests every 30 min during a 3-h match protocol. Muscle activation (twitch interpolation) and normalized EMG activity were assessed during maximal voluntary contraction (MVC) of plantar flexors. Spinal reflexes and M-waves were evoked at rest (i.e., H and M, respectively) and during MVC (i.e., H, V-wave, M, respectively). MVC torque declined significantly ( P<0.001) across the match protocol, due to decrease ( P<0.001) in muscle activation and in normalized EMG activity. The impairment in MVC was significantly correlated ( r=0.77; P<0.05) with the decline in muscle activation. H/ M ( P<0.001), H/ M ( P<0.01) and V/ M ( P<0.05) ratios were depressed with fatigue and decreased by ∼80%, 46% and 61% at the end of exercise, respectively. Simultaneously, peak twitch torque and M-wave amplitude were significantly ( P<0.01) altered with exercise, suggesting peripheral alterations. During prolonged tennis playing, the compromised voluntary strength capacity is linked to a reduced neural input to the working muscles. This central activation deficit partly results from a modulation in spinal loop properties. [ABSTRACT FROM AUTHOR]

To investigate the effect of supplementing high-volume endurance training with heavy strength training on muscle adaptations and physical performance in elite cross country skiers. Eleven male (18-26 years) and eight female (18-27 years) were assigned to either a strength group (STR) ( n=9) or a control group (CON) ( n=10). STR performed strength training twice a week for 12 weeks in addition to their normal endurance training. STR improved 1 repetition maximum (RM) for seated pull-down and half squat (19±2% and 12±2%, respectively), while no change was observed in CON. Cross-sectional area (CSA) increased in m. triceps brachii for both STR and CON, while there was no change in the m. quadriceps CSA. VO during skate-rollerskiing increased in STR (7±1%), while VO during running was unchanged. No change was observed in energy consumption during rollerskiing at submaximal intensities. Double-poling performance improved more for STR than for CON. Both groups showed a similar improvement in rollerski time-trial performance. In conclusion, 12 weeks of supplemental heavy strength training improved the strength in leg and upper body muscles, but had little effect on the muscle CSA in thigh muscles. The supplemental strength training improved both VO during skate-rollerskiing and double-poling performance. [ABSTRACT FROM AUTHOR]

Myostatin is a potent negative regulator of skeletal muscle mass, but its role in human skeletal muscle hypertrophy and atrophy is sparsely described. Muscle biopsies were obtained from young male subjects before and after 30 and 90 days of resistance training as well as after 3, 10, 30, 60 and 90 days of subsequent detraining. Myostatin mRNA increased significantly with detraining. We observed a 28 kDa myostatin immunoreactive protein, which, however, was also present in myostatin knock out mice skeletal muscle. As a novel finding we consistently detected a 10 kDa band, which may represent a mature myostatin monomer under reducing conditions or a novel, unknown myostatin form. Further, we observed a significant increase in this 10 kDa band after 3 days of detraining preceding the rapid type II fiber atrophy, in which almost half of the acquired fiber area was lost after only 10 days of detraining. Accordingly, an increase in the level of the 10 kDa protein is associated with rapid type II fiber atrophy, suggesting myostatin-mediated specific type II fiber atrophy, which in combination with our mRNA data support a role for myostatin in the negative regulation of adult human skeletal muscle mass. [ABSTRACT FROM AUTHOR]

Performance in intense exercise events, such as Olympic rowing, swimming, kayak, track running and track cycling events, involves energy contribution from aerobic and anaerobic sources. As aerobic energy supply dominates the total energy requirements after ∼75 s of near maximal effort, and has the greatest potential for improvement with training, the majority of training for these events is generally aimed at increasing aerobic metabolic capacity. A short-term period (six to eight sessions over 2–4 weeks) of high-intensity interval training (consisting of repeated exercise bouts performed close to or well above the maximal oxygen uptake intensity, interspersed with low-intensity exercise or complete rest) can elicit increases in intense exercise performance of 2–4% in well-trained athletes. The influence of high-volume training is less discussed, but its importance should not be downplayed, as high-volume training also induces important metabolic adaptations. While the metabolic adaptations that occur with high-volume training and high-intensity training show considerable overlap, the molecular events that signal for these adaptations may be different. A polarized approach to training, whereby ∼75% of total training volume is performed at low intensities, and 10–15% is performed at very high intensities, has been suggested as an optimal training intensity distribution for elite athletes who perform intense exercise events. [ABSTRACT FROM AUTHOR]

The present article reviews the physiological and performance effects of speed endurance training consisting of exercise bouts at near maximal intensities in already trained subjects. Despite a reduction in training volume, speed endurance training of endurance-trained athletes can maintain the oxidative capacity and improve intense short-duration/repeated high-intensity exercise performance lasting 30 s to 4 min, as it occurs in a number of sports. When combined with a basic volume of training including some aerobic high-intensity sessions, speed endurance training is also useful in enhancing performance during longer events, e.g. 40 K cycling and 10 K running. Athletes in team sports involving intense exercise actions and endurance aspects can also benefit from performing speed endurance training. These improvements don't appear to depend on changes in maximum oxygen uptake ( ), muscle substrate levels, glycolytic and oxidative enzymes activity, and membrane transport proteins involved in pH regulation. Instead they appear to be related to a reduced energy expenditure during submaximal exercise and a higher expression of muscle Na+,K+ pump α-subunits, which via a higher Na+,K+ pump activity during exercise may delay fatigue development during intense exercise. In conclusion, athletes from disciplines involving periods of intense exercise can benefit from the inclusion of speed endurance sessions in their training programs. [ABSTRACT FROM AUTHOR]

Training toward improving performance in sports involving high intense exercise can and is done in many different ways based on a mixture of tradition in the specific sport, coaches' experience and scientific recommendations. Strength training is a form of training that now-a-days have found its way into almost all sports in which high intense work is conducted. In this review we will focus on a few selected aspects and consequences of strength training; namely what effects do strength training have of muscle fiber type composition, and how may these effects change the contractile properties of the muscle and finally how will this affect the performance of the athlete. In addition, the review will deal with muscle hypertrophy and how it develops with strength training. Overall, it is not the purpose of this review to give a comprehensive up-date of the area, but to pin-point a few issues from which functional training advises can be made. Thus, more than a review in the traditional context this review should be viewed upon as an attempt to bring sports-physiologists and coaches or others working directly with the athletes together for a mutual discussion on how recently acquired physiological knowledge are put into practise. [ABSTRACT FROM AUTHOR]

Since long, motor imagery has been recognized as a method for studying motor representations. In the last few years, important advances regarding the use of motor imagery have been made. In particular, issues concerning the functional equivalence between imagery and action have been addressed, and how equivalence affects the use of imagery to study motor representations. In this paper, we review recent findings in order to highlight the current state of knowledge about motor imagery and its relation to motor action. Three topics are discussed: (i) the imagery perspective, (ii) task complexity, and (iii) the importance of physical experience. It is shown how theses factors are closely related and how previous studies may have underestimated to what extent these factors affect the interpretation of results. Practical implications for imagery interventions are considered. It is concluded that if you cannot perform an action physically, you cannot imagine it in a way that is necessary for a high degree of functional equivalence. [ABSTRACT FROM AUTHOR]

The author discusses issues related to cartesian dualism. The author supports the findings by Olsson and Nyberg on the lack of clear-cut separation between what the brain does when a person does physical training as compared with when a person is only thinking about it. According to the author, the body and the outside word are represented in the brain through the continuous interaction of a person with the environment.