Effects of playing surface on physiological responses and performance variables in a controlled football simulation

Abstract

In spite of the increased acceptance of artificial turf in football, few studies have investigated if matches are altered by the type of surface used and no research has compared physiological responses to football activity on artificial and natural surfaces. In the present study, participants performed a football match simulation on high-quality artificial and natural surfaces. Neither mean heart rate (171 ± 9 beats · min^?1 vs. 171 ± 9 beats · min^?1; P > 0.05) nor blood lactate (4.8 ± 1.6 mM vs. 5.3 ± 1.8 mM; P > 0.05) differed between the artificial and natural surface, respectively. Measures of sprint, jumping and agility performance declined through the match simulation but surface type did not affect the decrease in performance. For example, the fatigue index of repeated sprints did not differ (P > 0.05) between the artificial, (6.9 ± 2.1%) and natural surface (7.4 ± 2.4%). The ability to turn after sprinting was affected by surface type but this difference was dependent on the type of turn. Although there were small differences in the ability to perform certain movements between artificial and natural surfaces, the results suggest that fatigue and physiological responses to football activity do not differ markedly between surface-type using the high-quality pitches of the present study.     

A Nomogram for the Estimate of Percent Body Fat from Generalized Equations

Abstract

Fifteen well-conditioned college women, who had been thoroughly trained in the correct technique for women's push-ups, were tested for maximal pushing strength in two positions and for the number of complete push-ups they were able to perform at the rate of 41 push-ups per minute. For statistical purposes, calculations of maximal strength for each individual were based upon the average of the recorded maximal arm strengths in the high and low positions plus the average of the weight supported in the high and low positions. The work load was calculated from the distance between the high and low positions, the average supported weight, and the number of push-ups the subject was able to perform until exhausted. A correlation coefficient of .76 was obtained between the calculated maximal strength measures and the work load, indicating a statistically significant positive relationship.     

Hematological Variations during Aerobic Training of College Women

Abstract

The purpose of this study was to observe the effects of a progressive aerobic training program on hemoglobin concentration (Hb), hematocrit (Hct), red blood cell (RBC) count, mean RBC size (MCV), and mean corpuscular hemoglobin (MCH) of college women (N = 19). Training consisted of jogging (3 × week) one mile per session (Week 1) with a progressive increase in duration to five miles per session (Week 9). Training intensity elicited heart rates between 165–185 beats per minute. Blood samples were taken before training and after approximately two, five, seven, and nine weeks. Maximal oxygen uptake (ml/kg · min^?1) increased significantly during training from 41.2 ± 0.7 ( ± SE) to 44.7 ± 0.7. Initial values of Hb, Hct, RBC count, MCV, and MCH were 14.7 ± 0.13 g/dl, 40.4 ± 0.46%, 4.5 ± 0.5 × 10⁶/mm³, 89.0 ± 1.1/μ³, and 32.4 ± 0.4 μμg respectively. Orthogonal polynominal regression indicated significant decreasing quadratic trends for Hb, Hct, and RBC count, a significant cubic trend for MCV, and no change in MCH during training. Despite the initial trends, values that changed did return to near pretraining levels by the end of the nine-week program. Values for all blood parameters remained within normal ranges throughout the study. These data suggest that although aerobic training of increasing intensity in young women may be accompanied initially by decreases in Hb, Hct, and RBC count and an increase in MCV, these changes are only transitory. If such changes result from RBC destruction rather than hemodilution, the return to hematopoietic balance could impose a draw on body iron stores.     

Stimulus Velocity,Duration and Uncertainty as Determiners of Response Structure and Timing Accuracy

Abstract

The present experiments examined the effects of stimulus velocity, stimulus duration, and stimulus uncertainty on the spatial-temporal structure and timing accuracy of coincident timing responses. The results of Experiment 1 indicated that the response structure for aimed movements differed from that of ballistic movements but response accuracy was comparable for both movement conditions. However, when information concerning the stimulus velocity was provided, the responses to the faster stimuli (i.e., stimuli of shorter duration) appeared to be “speeded up” copies of those to slower stimuli and response accuracy increased as the stimulus velocity increased (i.e., stimulus duration decreased). When the stimulus velocity was not known, subjects initiated a common response for approximately 260 msec and response accuracy appeared to decrease as the stimulus velocity increased (i.e., stimulus duration decreased). Experiment 2 indicated that the stimulus duration rather than the stimulus velocity was the major determiner of both the spatial-temporal structure and timing accuracy and that a very fast and a very slow stimulus will be responded to similarly when the stimulus duration remains constant.     

Predicting Future Trends in Adult Fitness Using the Delphi Approach

Abstract

This study determined how experts see the future of adult fitness by using the Delphi Technique as a measurement tool. Experts (n = 50), all Fellows of the American College of Sports Medicine, were selected on the basis of their reputations in adult fitness. Three questionnaires were submitted to the panel. In the first questionnaire each expert listed five or more events, trends, or developments they thought would take place and five or more events they would like to see take place in the next 25 years. From the events and trends listed on this questionnaire, 100 items were generated that formed the basis for the last two questionnaires. Responses to the items on the second questionnaire were evaluated on a 5-point Likert scale for probability and desirability. In the third questionnaire, group means and standard deviations were calculated and recorded for each item. Only those items which were significantly (p < .01) higher than 3.0, the average probability or desirability response on the Likert scale, were included in the analysis. The items were divided into seven categories: fitness in sport and recreation, fitness and wellness, fitness in industry, fitness in education, fitness in business, research in fitness, and fitness equipment and facilities. The highest single mean for any item for both probability (M = 4.31) and desirability (M = 4.83) was increased awareness of health and fitness among the elderly.