Letters     

Sidney E. Jones 《The Urban Review》1968,2(5):30-31

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Variations of stroking parameters associated with 200 m competitive performance improvement in top-standard front crawl swimmers     

Huot-Marchand F  Nesi X  Sidney M  Alberty M  Pelayo P 《Sports biomechanics / International Society of Biomechanics in Sports》2005,4(1):89-99

The aim of this study was to analyse the variations of stroking parameters (speed, stroke length, stroke rate, and stroke index) associated with the 200 m front crawl competitive performance improvement. Two races completed by 17 top swimmers were analysed in the 200 m freestyle final of French or European championships, each final being separated by two years. All the swimmers' performances were bettered in the second race (mean +/- SD: 113.44 +/- 2.50 vs 111.78 +/- 2.71 s; p < 0.01) and were associated with a significant increase of stroke rate without variation of average stroke length and stroke index values (p > 0.05). Swimmers emphasized the first part of the race, with higher speed in the first three lengths, higher stroke rate in the first two lengths and lower stroke length in the first one. Stroke length and stroke rate variations were highly correlated (r = 0.98; p < 0.05). In 11 of the 17 swimmers, the improvement was concomitant with a decrease in stroke length and an increase in stroke rate. Only one swimmer's improvement was associated with a substantial increase in stroke length. These results highlighted that stroke length and stroke index cannot be considered as the only parameters linked to improvement in a 200 m crawl in adult swimmers competing at high standard. Moreover, an increase in stroke rate associated with a slight decrease in stroke length should not be considered as ineffective, especially at top standard.  相似文献   

A descriptive analysis of elite-level racquetball     

A W Salmoni  K Sidney  R Michel  J Hiser  K Langlotz 《Research quarterly for exercise and sport》1991,62(1):109-114

The results of the three experiments provide insight into the time/motion characteristics of racquetball and the physiological responses of elite-level racquetball players during competition. The maximum oxygen uptakes of the male and female athletes tested were relatively low in comparison to those of other elite-level sports, suggesting that aerobic demand, although necessary, is probably not a limiting factor at this level of racquetball play. Racquetball games at the elite level last from 10 to 15 min, and the distance covered by each player during this time is minimal. Even though the rest periods between rallies are from one to two times as long as the work intervals, the work intensity during the rallies is sufficient to produce an average heart rate of between 75 and 95% of maximum throughout most of a game. Although some lactic acid accumulates in the blood, the concentration remains at a steady state during a game (10 to 30% of maximum).  相似文献   

II. THE CONGRESS: A MALAYAN VIEW     

Sir Sidney Caine 《Higher Education Quarterly》1954,8(2):128-135

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Letters     

Sidney G. Tickton 《Educational technology research and development : ETR & D》1972,20(2):223-224

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Acknowledgments     

Sidney E. Benton 《ASHE Higher Education Report》1982,11(1):VI-VI

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Intracultural communication rules and outcomes within three domestic cultures     

Mary Jane Collier  Sidney A. Ribeau 《Int J Intercult Relat》1986,10(4)

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Neural mechanisms of strength increase after one-week motor imagery training     

Sidney Grosprêtre  Thomas Jacquet  Florent Lebon  Charalambos Papaxanthis  Alain Martin 《European Journal of Sport Science》2018,18(2):209-218

The neural mechanisms explaining strength increase following mental training by motor imagery (MI) are not clearly understood. While gains are mostly attributed to cortical reorganization, the sub-cortical adaptations have never been investigated. The present study investigated the effects of MI training on muscle force capacity and the related spinal and supraspinal mechanisms. Eighteen young healthy participants (mean age: 22.5?±?2.6) took part in the experiment. They were distributed into two groups: a control group (n?=?9) and an MI training group (n?=?9). The MI group performed seven consecutive sessions (one per day) of imagined maximal isometric plantar flexion (4 blocks of 25 trials per session). The control group did not engage in any physical or mental training. Both groups were tested for the isometric maximal plantar flexion torque (MVC) and the rate of torque development (RTD) before and after the training session. In addition, soleus and medial gastrocnemius spinal and supraspinal adaptations were assessed through the recording of H-reflexes and V-waves, with electrical stimulations of the posterior tibial nerve evoked at rest and during MVC, respectively. After one week, only the MI training group increased both plantar flexion MVC and RTD. The enhancement of muscle torque capacity was accompanied by significant increase of electromyographic activity and V-wave during MVC and of H-reflex at rest. The increased cortical descending neural drive and the excitability of spinal networks at rest could explain the greater RTD and MVC after one week of MI training.  相似文献   

Greater fatigability in knee-flexors vs. knee-extensors after a standardized fatiguing protocol     

Giuseppe Coratella  Sidney Grosprêtre  Philippe Gimenez  Laurent Mourot 《European Journal of Sport Science》2018,18(8):1110-1118

The present study aimed to investigate the effects of a standardized fatiguing protocol on central and peripheral fatigue in knee-flexors and knee-extensors. Thirteen healthy men (age: 23?±?3 years; height: 1.78?±?0.09 m; body-mass: 73.6?±?9.2?kg) volunteered for the present study. Maximal voluntary contraction (MVC), Electromyography (EMG) activity, voluntary activation level (VAL) as an index of central fatigue and twitch potentiation as an index of peripheral fatigue were measured before and after the fatiguing protocol. The fatiguing protocol consisted of a 0.6 duty-cycle to exhaustion (6?s isometric contraction, 4?s recovery) at 70% MVC. After the fatiguing protocol, MVC decreased in both (Effect-size (ES)?=?1.14) and knee-extensors (ES?=?1.14), and EMG activity increased in both knee-flexors (ES?=?2.33) and knee-extensors (ES?=?1.54). Decreases in VAL occurred in knee-flexors (ES?=?0.92) but not in knee-extensors (ES?=?0.04). Decreases in potentiation occurred in both knee-flexors (ES?=?0.84) and knee-extensors (ES?=?0.58). The greater central occurrence of fatigue in knee-flexors than in knee-extensors may depend on the different muscle morphology and coupled with a greater tolerance to fatigue in knee-extensors. The present data add further insight to the complicated knee-flexors-to-knee-extensors strength relationship and the mechanisms behind the different occurrence of fatigue.  相似文献   

Simple networks: A way of sharing information     

Donald Armel  Sidney Leland Stepp 《Performance Improvement》1991,30(8):36-37

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