Relative shank to thigh length is associated with different mechanisms of power production during elite male ergometer rowing

The effect of anthropometric differences in shank to thigh length ratio upon timing and magnitude of joint power production during the drive phase of the rowing stroke was investigated in 14 elite male rowers. Rowers were tested on the RowPerfect ergometer which was instrumented at the handle and foot stretcher to measure force generation, and a nine segment inverse dynamics model used to calculate the rower's joint and overall power production. Rowers were divided into two groups according to relative shank thigh ratio. Time to half lumbar power generation was significantly earlier in shorter shank rowers (p = 0.028) compared to longer shank rowers, who showed no lumbar power generation during the same period of the drive phase. Rowers with a relatively shorter shank demonstrated earlier lumbar power generation during the drive phase resulting from restricted rotation of the pelvic segment requiring increased lumbar extension in these rowers. Earlier lumbar power generation and extension did not appear to directly affect performance measures of the short shank group, and so can be attributed to a technical adaptation developed to maximise rowing performance.     

A review on the basketball jump shot

The ability to shoot an effective jump shot in the sport of basketball is critical to a player's success. In an attempt to better understand the aspects related to expert performance, researchers have investigated successful free throws and jump shots of various basketball players and identified movement variables that contribute to their success. The purpose of this study was to complete a systematic review of the scientific literature on the basketball free throw and jump shot for the purpose of revealing the critical components of shooting that coaches, teachers, and players should focus on when teaching, learning, practising, and performing a jump shot. The results of this review are presented in three sections: (a) variables that affect ball trajectory, (b) phases of the jump shot, and (c) additional variables that influence shooting.     

Acute effects of intense interval training on running mechanics

The aims of this study were to determine if there are significant kinematic changes in running pattern after intense interval workouts, whether duration of recovery affects running kinematics, and whether changes in running economy are related to changes in running kinematics. Seven highly trained male endurance runners (VO 2max = 72.3 +/- 3.3 ml kg -1 min -1 ; mean +/- s) performed three interval running workouts of 10 X 400 m at a speed of 5.94 +/- 0.19 m s -1 (356 +/- 11.2 m min -1 ) with a minimum of 4 days recovery between runs. Recovery of 60, 120 or 180 s between each 400 m repetition was assigned at random. Before and after each workout, running economy and several kinematic variables were measured at speeds of 3.33 and 4.47 m s -1 (200 and 268 m min -1 ). Speed was found to have a significant effect on shank angle, knee velocity and stride length (P ? 0.05). Correlations between changes pre- and post-test for VO 2 (ml kg -1 min -1 ) and several kinematic variables were not significant (P > 0.05) at both speeds. In general, duration of recovery was not found to adversely affect running economy or the kinematic variables assessed, possibly because of intra-individual adaptations to fatigue.     

Effect of 6 weeks of endurance training on the lactate minimum speed

The aim of this study was to assess the sensitivity of the lactate minimum speed test to changes in endurance fitness resulting from a 6 week training intervention. Sixteen participants (mean +/- s :age 23 +/- 4 years;body mass 69.7 +/- 9.1 kg) completed 6 weeks of endurance training. Another eight participants (age 23 +/- 4 years; body mass 72.7 +/-12.5 kg) acted as non-training controls. Before and after the training intervention, all participants completed: (1) a standard multi-stage treadmill test for the assessment of VO 2max , running speed at the lactate threshold and running speed at a reference blood lactate concentration of 3 mmol.l -1 ; and (2) the lactate minimum speed test, which involved two supramaximal exercise bouts and an 8 min walking recovery period to increase blood lactate concentration before the completion of an incremental treadmill test. Additionally, a subgroup of eight participants from the training intervention completed a series of constant-speed runs for determination of running speed at the maximal lactate steady state. The test protocols were identical before and after the 6 week intervention. The control group showed no significant changes in VO 2max , running speed at the lactate threshold, running speed at a blood lactate concentration of 3 mmol.l -1 or the lactate minimum speed.In the training group, there was a significant increase in VO 2max (from 47.9 +/- 8.4 to 52.2 +/- 2.7 ml.kg -1 .min -1 ), running speed at the maximal lactate steady state (from 13.3 +/- 1.7 to 13.9 +/- 1.6 km.h -1 ), running speed at the lactate threshold (from 11.2 +/- 1.8 to 11.9 +/- 1.8 km.h -1 ) and running speed at a blood lactate concentration of 3 mmol.l -1 (from 12.5 +/- 2.2 to 13.2 +/- 2.1 km.h -1 ) (all P ? 0.05). Despite these clear improvements in aerobic fitness, there was no significant difference in lactate minimum speed after the training intervention (from 11.0 +/- 0.7 to 10.9 +/- 1.7 km.h -1 ). The results demonstrate that the lactate minimum speed,when assessed using the same exercise protocol before and after 6 weeks of aerobic exercise training, is not sensitive to changes in endurance capacity.     

The influence of intermittent high-intensity shuttle running and fluid ingestion on the performance of a soccer skill

The aim of this study was to examine the effect of intermittent high-intensity shuttle running and fluid ingestion on the performance of a soccer skill. Nine semi-professional soccer players volunteered to participate in the study. Their mean (± _sx ) age, body mass and maximal oxygen uptake were 20.2 ± 0.4 years, 73.2 ± 1.8 kg and 59.1 ± 1.3 ml·kg^-1 ·min^-1 respectively. The players were allocated to two randomly assigned trials: ingesting or abstaining from fluid intake during a 90 min intermittent exercise protocol (Loughborough Intermittent Shuttle Test:LIST).This test was designed to simulate the minimum physical demands faced by soccer players during a game. Before and immediately after performance of the test,the players completed a soccer skill test and a mental concentration test. Performance of the soccer skill test after the 'no-fluid' trial deteriorated by 5% (P ? 0.05),but was maintained during the fluid trial. Mean heart rate, perceived exertion, serum aldosterone, osmolality, sodium and cortisol responses during the test were higher (P ? 0.05) in the 'no-fluid' trial than in the fluid trial. The results of this study suggest that soccer players should consume fluid throughout a game to help prevent a deterioration in skill performance.     

Sociology of Physical Educator/Coaches: Personal Attributes Controversy

Abstract

In the first article, John W. Loy discusses the identification of sport sociology as an academic specialty and describes its stages of development. Loy identifies problems confronting future developments in sport sociology, in particular critical mass, academic status, and ideological orientation, both in physical education and in sociology. This analysis is followed by a sociological analysis of sports occupations, by George H. Sage. Sage discusses the personal attributes of physical educators and coaches, focusing on personality characteristics, leadership styles, attitudes, and value orientations. The paper is concluded with an attempt to resolve the controversy between the stereotype of physical educator/coach in the popular literature and the findings from empirical research.     

Properties of Isokinetic Fatigue at Various Movement Speeds in Adult Males

Abstract

Eighteen male subjects, ages 20–28 years, engaged in three fatigue bouts using an isokinetic dynamometer (Cybex II). Maximum knee extension contractions were given for 100 s at a rate of 30 per minute. The three contraction speeds chosen were 120° · s ^–1 160° · s ^–1 and 200° · s ^–1.Peak torque at 120° · s ^–1 was significantly greater (p <.05) than at 200° · s ^–1 for the first 60 s, and 160° · s ^–1 for the first 50 s. Thereafter, no significant differences existed among conditions. All three curves were found to follow two-component exponential functions as shown by the equation y_t =a ₂ e^k2^t – a ₁ e^k1^t + c. The three curves possessed similar rate constants for both components. Time to peak torque was achieved at similar times for testing at 160 and 200° · s ^–1 (p <.05). It is concluded that peak torque varies inversely with movement speed, and that the pattern of decrement is independent of movement speed. Time to peak torque does not appear to change significantly across trials in isokinetic fatigue.     

Cognitive Style and Learner Strategy Interaction in the Performance of Primary and Related Maze Tasks

Abstract

The effect of designated learning strategies and reflective versus impulsive cognitive styles on performance in a maze learning task was investigated. Twenty-four female subjects were randomly assigned to a strategy or control group. The strategies group was provided with three potentially effective strategies (imagery, rhythm, and feedback) as identified by an information processing task analysis procedure. The Matching Familiar Figures test further classified subjects within the two groups according to their preferred styles of responding. Eleven primary task trials were administered with direct view of maze and four related task trials were completed with an indirect view of it. Traversal speed and time in the incorrect pathways were analyzed with a 2 × 2 × 7 (Strategies × Cognitive Styles × Trial Blocks) repeated measures ANOVA. A significant three-way interaction was found for both dependent measures. As hypothesized, during the primary task the control reflective subjects traversed the maze more slowly than the control impulsive subjects. However, the strategies reflective subjects completed the maze with the same speed as strategies impulsives. The incorrect pathways × time interaction revealed that the control reflective subjects spent less time in the incorrect pathways during the related task than the control impulsives. No significant differences were found for strategies reflectives or impulsives. These findings indicate that, for this maze task that emphasized speed, the performance of reflective and impulsive subjects was facilitated by appropriate learning strategies.     

Differential Effects of Three Teachers Over a Unit of Instruction

The purpose of this study was to describe the effects of three teachers on psychomotor, affective, and cognitive outcomes over a 15-lesson volleyball unit. Three intact middle school physical education classes were used. Pre- and posttests were administered for the overhead set, forearm pass, and serve psychomotor skills. A semantic differential test with four affective dimensions and a written test on the rules, strategies, and mechanics of volleyball were also administered pre- and posttest. Data on instructional characteristics were obtained using academic learning time (ALT-PE); observation system for content development (OSCD-PE), and a content analysis of lessons.

The following were key aspects of the results: (a) Teachers differed in their approaches to the content of the unit more than in the characteristics of their instruction as determined through observational data; (b) teachers differed in respect to the psychomotor skills for which they were able to produce statistically significant student gain; (c) the skill level of students played a major role in psychomotor outcomes; (d) affective measures started high and remained high from pre- to posttest with significant change occurring positively with the low-skilled in one measure; (d) cognitive learning was significant from pre- to posttest in rules and mechanics but not in strategies. Instructional characteristics, as described in this study, did not change from skill to skill, but student learning did. This led the authors to conclude that the instrumentation for instructional variables was not sensitive to differences in the way individual skills were handled by individual teachers.     

Lactate and Phosphagen Levels in Muscle Immediately after a Maximum 300 m Run at Sea Level

Abstract

The relative effectiveness of six intensive training programs on the development of four selected skills was studied, with emphasis on limited time encountered within the semester organizational plan. One hundred and twenty college freshmen men volunteers were randomly assigned to training groups of 30 members each, which met for two sessions a week for 16 weeks.

Results indicated that: (a) direct practice jumping, alone or combined with repetitive sprinting or weight training, was significantly superior to weight training alone on standing broad jump development; (b) direct practice of a zigzag run was superior to both weight training and repetitive sprinting; and (c) when group acquisition of “adequate” skill is the objective, performance improvements educed over the first nine weeks were great enough to question the merits of persisting at an activity over a full semester. Only the zigzag run was adversely affected by the spring vacation cessation of training.