Physiological determinants of climbing-specific finger endurance and sport rock climbing performance

The aim of the study was to examine several physiological responses to a climbing-specific task to identify determinants of endurance in sport rock climbing. Finger strength and endurance of intermediate rock climbers (n = 11) and non-climbers (n = 9) were compared using climbing-specific apparatus. After maximum voluntary contraction (MVC) trials, two isometric endurance tests were performed at 40% (s = 2.5%) MVC until volitional exhaustion (continuous contractions and intermittent contractions of 10 s, with 3 s rest between contractions). Changes in muscle blood oxygenation and muscle blood volume were recorded in the flexor digitorum superficialis using near infra-red spectroscopy. Statistical significance was set at P < 0.05. Climbers had a higher mean MVC (climbers: 485 N, s = 65; non-climbers 375 N, s = 91) (P = 0.009). The group mean endurance test times were similar. The force-time integral, used as a measure of climbing-specific endurance, was greater for climbers in the intermittent test (climbers: 51,769 N x s, s = 12,229; non-climbers: 35,325 N x s, s = 9724) but not in the continuous test (climbers: 21,043 N x s, s = 4474; non-climbers: 15,816 N x s, s = 6263). Recovery of forearm oxygenation during rest phases (intermittent test) explained 41.1% of the variability in the force-time integral. Change in total haemoglobin was significantly greater in non-climbers (continuous test) than climbers (P = 0.023--40% test timepoint, P = 0.014--60% test timepoint). Pressor responses were similar between groups and not related to the force-time integral for either test. We conclude that muscle re-oxygenation during rest phases is a predictor of endurance performance.     

Physiological determinants of climbing-specific finger endurance and sport rock climbing performance

Abstract

The aim of the study was to examine several physiological responses to a climbing-specific task to identify determinants of endurance in sport rock climbing. Finger strength and endurance of intermediate rock climbers (n = 11) and non-climbers (n = 9) were compared using climbing-specific apparatus. After maximum voluntary contraction (MVC) trials, two isometric endurance tests were performed at 40% (s = 2.5%) MVC until volitional exhaustion (continuous contractions and intermittent contractions of 10 s, with 3 s rest between contractions). Changes in muscle blood oxygenation and muscle blood volume were recorded in the flexor digitorum superficialis using near infra-red spectroscopy. Statistical significance was set at P < 0.05. Climbers had a higher mean MVC (climbers: 485 N, s = 65; non-climbers 375 N, s = 91) (P = 0.009). The group mean endurance test times were similar. The force – time integral, used as a measure of climbing-specific endurance, was greater for climbers in the intermittent test (climbers: 51,769 N · s, s = 12,229; non-climbers: 35,325 N · s, s = 9724) but not in the continuous test (climbers: 21,043 N · s, s = 4474; non-climbers: 15,816 N · s, s = 6263). Recovery of forearm oxygenation during rest phases (intermittent test) explained 41.1% of the variability in the force – time integral. Change in total haemoglobin was significantly greater in non-climbers (continuous test) than climbers (P = 0.023 – 40% test timepoint, P = 0.014 – 60% test timepoint). Pressor responses were similar between groups and not related to the force – time integral for either test. We conclude that muscle re-oxygenation during rest phases is a predictor of endurance performance.     

The influence of squat depth on maximal vertical jump performance

An increase in the period over which a muscle generates force can lead to the generation of greater force and, therefore, for example in jumping, to greater jump height. The aim of this study was to examine the effect of squat depth on maximum vertical jump performance. We hypothesized that jump height would increase with increasing depth of squat due to the greater time available for the generation of muscular force. Ten participants performed jumps from preferred and deep squat positions. A computer model simulated jumps from the different starting postures. The participants showed no difference in jump height in jumps from deep and preferred positions. Simulated jumps produced similar kinematics to the participants' jumps. The optimal squat depth for the simulated jumps was the lowest position the model was able to jump from. Because jumping from a deep squat is rarely practised, it is unlikely that these jumps were optimally coordinated by the participants. Differences in experimental vertical ground reaction force patterns also suggest that jumps from a deep squat are not optimally coordinated. These results suggest there is the potential for athletes to increase jump performance by exploiting a greater range of motion.     

江西省攀岩运动市场推广现状与策略研究

采用文献资料法、专家访谈法、问卷调查法,对江西省攀岩运动的现状与发展策略进行研究,结果表明:江西省青少年攀岩推广缓慢;与旅游结合的发展试点较少,开发规模也较小,未能形成项目品牌;进入商场体验推广困难;在户外拓展训练项目中推广前景较大.建议加强市场竞争管理,学习国内成功市场化运作经验,打造江西攀岩运动特色品牌,加强社会性合作.     

Pole length and ground reaction forces during maximal double poling in skiing

The purpose of the investigation was to study the relationship between thrust phase duration, ground reaction force, velocity increase after pole thrust and pole angles versus pole length during double poling in roller skiing. Seven male regional elite cross-country skiers volunteered as subjects for the study. The subjects performed a maximal double pole thrust on roller skis with each of the three different pole lengths: 'short', self-selected (normal) and 'long'. The short and long poles were 7.5 cm shorter and 7.5 cm longer than the self-selected pole length. The subjects made seven maximal pole thrusts with each pole length, which were randomly selected during 21 trials. For each trial the subjects accelerated from a 1.2 m high downhill slope attaining a speed of 3.92 m.s-1 before making a maximal double pole thrust on a force plate placed at the bottom of the slope. The vertical (F2), anterior-posterior (Fy) and mediolateral (Fx) reaction forces of the left pole were measured by the force plate. The positions of the pole were recorded in 3-D by an opto-electronic system. Thrust phase duration, impulse, mean force, velocity increase after pole thrust and pole angles were calculated from the recorded data. Double poling with long poles produced a significantly larger propulsive anterior-posterior reaction force impulse and velocity increase than normal (p < .05) and short poles (p < .05). This was in spite of a larger mean anterior-posterior reaction force being produced with short poles. Thus, thrust phase duration was a primary factor in determining propulsive anterior-posterior impulse. For the practitioner, the results can be useful in the selection of pole length when the aim is to increase thrust phase duration, anterior-posterior force impulse and velocity.     

Use of 'chalk' in rock climbing: sine qua non or myth?

Magnesium carbonate, or 'chalk', is used by rock climbers to dry their hands to increase the coefficient of friction, thereby improving the grip of the holds. To date, no scientific research supports this practice; indeed, some evidence suggests that magnesium carbonate could decrease the coefficient of friction. Fifteen participants were asked to apply a force with the tip of their fingers to hold a flattened rock (normal force), while a tangential force pulled the rock away. The coefficient of friction--that is, the ratio between the tangential force (pulling the rock) and the normal force (applied by the participants)--was calculated. Coating (chalk vs no chalk), dampness (water vs no water) and rock (sandstone, granite and slate) were manipulated. The results showed that chalk decreased the coefficient of friction. Sandstone was found to be less slippery than granite and slate. Finally, water had no significant effect on the coefficient of friction. The counter-intuitive effect of chalk appears to be caused by two independent factors. First, magnesium carbonate dries the skin, decreasing its compliance and hence reducing the coefficient of friction. Secondly, magnesium carbonate creates a slippery granular layer. We conclude that, to improve the coefficient of friction in rock climbing, an effort should be made to remove all particles of chalk; alternative methods for drying the fingers are preferable.     

我国攀岩运动后备人才培养模式探讨

根据实际情况,阐述了我国攀岩运动后备人才培养的新模式,旨在为攀岩运动在我国更好的发展提供参考。     

The effect of the bend on technique and performance during maximal effort sprinting

This study investigated changes in performance and technique that occur during maximal effort bend sprinting compared with straight-line sprinting under typical outdoor track conditions. Utilising a repeated measures design, three-dimensional video analysis was conducted on seven male sprinters in both conditions (bend radius: 37.72 m). Mean race velocity decreased from 9.86 to 9.39 m/s for the left step (p = 0.008) and from 9.80 to 9.33 m/s for the right step (p = 0.004) on the bend compared with the straight, a 4.7% decrease for both steps. This was mainly due to a 0.11 Hz (p = 0.022) decrease in step frequency for the left step and a 0.10 m (p = 0.005) reduction in race step length for the right step. The left hip was 4.0° (p = 0.049) more adducted at touchdown on the bend than the straight. Furthermore, the bend elicited significant differences between left and right steps in a number of variables including ground contact time, touchdown distance and hip flexion/extension and abduction/adduction angles. The results indicate that the roles of the left and right steps may be functionally different during bend sprinting. This specificity should be considered when designing training programmes.     

Effect of vibratory stimulation training on maximal force and flexibility

In this study, we investigated a new method of training for maximal strength and flexibility, which included exertion with superimposed vibration (vibratory stimulation, VS) on target muscles. Twenty‐eight male athletes were divided into three groups, and trained three times a week for 3 weeks in one of the following conditions: (A) conventional exercises for strength of the arms and VS stretching exercises for the legs; (B) VS strength exercises for the arms and conventional stretching exercises for the legs; (C) irrelevant training (control group). The vibration was applied at 44 Hz while its amplitude was 3 mm. The effect of training was evaluated by means of isotonic maximal force, heel‐to‐heel length in the two‐leg split across, and flex‐and‐reach test for body flexion. The VS strength training yielded an average increase in isotonic maximal strength of 49.8%, compared with an average gain of 16% with conventional training, while no gain was observed for the control group. The VS flexibility training resulted in an average gain in the legs split of 14.5 cm compared with 4.1 cm for the conventional training and 2 cm for the control groups, respectively. The ANOVA revealed significant pre‐post training effects and an interaction between pre‐post training and ‘treatment’ effects (P< 0.001) for the isotonic maximal force and both flexibility tests. It was concluded that superimposed vibrations applied for short periods allow for increased gains in maximal strength and flexibility.     

高校体育开展垂钓、攀岩合并课的探讨

运用比较法和问卷法对华南理工大学2003、2004级部分学生体育课开设钓鱼、攀岩合并课进行探讨发现,高校体育课中开设钓鱼、攀岩合并课能很好地培养学生耐性和提高学生体质,且学生对该课程的兴趣度极高;同时还分析了高校开设垂钓、攀岩合并课在场地设施、师资力量等方面具有较好条件,并提出高校体育课应开展垂钓、攀岩课,以丰富和满足学生对多种体育项目的追求。     

Differences in technique between sprinters and distance runners at equal and maximal speeds

In the finishing kick of a distance race, maximizing speed becomes the focus even if economy may be sacrificed. If distance runners knew how to alter their technique to become more sprint-like, this process could be more successful. In this study, we compared the differences in technique between sprinters and distance runners while running at equal and maximal speeds. Athletes consisted of 10 Division I distance runners, 10 Division I sprinters, and 10 healthy non-runners. They performed two tests, each consisting of a 60-m run on the track: Test 1 at a set pace of 5.81 m/s, while Test 2 was maximal speed. Video was collected at 180 Hz. Significant differences (P < 0.05) between the sprint and distance groups at maximal speeds were found in the following areas: speed, minimum hip angle, knee extension at toe-off, stride length, contact time, and recovery knee at touchdown. In Test 1, sprinters and distance runners displayed many of the same significant differences. The control group was similar to the distance group in both trials. As distance runners attempt to sprint, the desired adjustments do not necessarily occur. Distance runners may benefit from biomechanical interventions to improve running speed near the end of a race.     

Differences in technique between sprinters and distance runners at equal and maximal speeds

In the finishing kick of a distance race, maximizing speed becomes the focus even if economy may be sacrificed. If distance runners knew how to alter their technique to become more sprint-like, this process could be more successful. In this study, we compared the differences in technique between sprinters and distance runners while running at equal and maximal speeds. Athletes consisted of 10 Division I distance runners, 10 Division I sprinters, and 10 healthy non-runners. They performed two tests, each consisting of a 60-m run on the track: Test 1 at a set pace of 5.81 m/s, while Test 2 was maximal speed. Video was collected at 180 Hz. Significant differences (P < 0.05) between the sprint and distance groups at maximal speeds were found in the following areas: speed, minimum hip angle, knee extension at toe-off, stride length, contact time, and recovery knee at touchdown. In Test 1, sprinters and distance runners displayed many of the same significant differences. The control group was similar to the distance group in both trials. As distance runners attempt to sprint, the desired adjustments do not necessarily occur. Distance runners may benefit from biomechanical interventions to improve running speed near the end of a race.     

Changes in the perception of action possibilities while climbing to fatigue on a climbing wall

In two experiments we examined changes in the perception of action possibilities as a function of exertion. In Experiment 1, participants repeatedly climbed on a climbing wall in a series of trials that progressively increased in number to 10 trials, resulting in increased exertion. Before and during climbing, the participants judged their maximum reaching height and perceived exertion. On a separate day, participants climbed another 10 trials while performing actual maximum reaches. Higher perceived exertion was associated with decreases in perceived maximum reach while the actual reaches did not decrease. However, the perceptual changes occurred early during task execution when the participants were not yet fatigued. When exertion set in, neither perceived nor actual maximum reaching appeared to be affected. In Experiment 2, we included exhaustion trials. The findings replicated the early changes in perception observed in Experiment 1, which may be explained by hands-on experience with the task. Furthermore, while climbing to exhaustion, perceptual judgements largely changed in keeping with changes in the actual maximum reach. Thus, there appeared to be a functional relationship between participants' actual action capabilities, rather than their state of physical fatigue per se, and perceived action possibilities.     

The influence of anxiety on visual attention in climbing

The object of the current study was to investigate anxiety-induced changes in movement and gaze behavior in novices on a climbing wall. Identical traverses were situated at high and low levels on a climbing wall to manipulate anxiety. In line with earlier studies, climbing times and movement times increased under anxiety. These changes were accompanied by similar changes in total and average fixation duration and the number of fixations, which were primarily aimed at the holds used for climbing. In combination with these findings, a decrease in search rate provided evidence for a decrease in processing efficiency as anxiety increased.     

Effect of 12 weeks of training on critical velocity and maximal lactate steady state in swimmers

Abstract

The aim of this study was to determine the effect of 12 weeks of training on the critical velocity and maximal lactate steady state of elite swimmers. The tests to determine critical velocity and maximal lactate steady state were performed before and after 12 weeks of training. Critical velocity after 12 weeks of training was significantly higher than before training (1.45±0.10 m · s^?1 vs. 1.41±0.11 m · s^?1). In contrast, no significant differences in the velocity at maximal lactate steady state were observed before and after training (1.41±0.10 m · s^?1 vs. 1.43±0.10 m · s^?1). There was also a decrease in mean lactate concentration after 12 weeks of training. Before training, the velocity at maximal lactate steady state occurred at 100% of critical velocity, with a mean lactate concentration of 4.34 mmol · l^?1. After training, the velocity at maximal lactate steady state occurred at 98% of critical velocity, with a reduced mean lactate concentration of 3.69 mmol · l^?1. Based on these results, it would appear that 12 weeks of training was enough to promote an increase in critical velocity. Although no significant differences in the velocity at maximal lactate steady state were observed before and after training, the decrease in mean lactate concentration after training demonstrated greater efficiency of the aerobic system, leading to less wear during the tests.