Increasing hip and knee flexion during a drop-jump task reduces tibiofemoral shear and compressive forces: implications for ACL injury prevention training

Although most ACL injury prevention programmes encourage greater hip and knee flexion during landing, it remains unknown how this technique influences tibiofemoral joint forces. We examined whether a landing strategy utilising greater hip and knee flexion decreases tibiofemoral anterior shear and compression. Twelve healthy women (25.9 ± 3.5 years) performed a drop-jump task before and after a training session (10–15 min) that emphasised greater hip and knee flexion. Peak tibiofemoral anterior shear and compressive forces were calculated using an electromyography (EMG)-driven knee model that incorporated joint kinematics, EMG and participant-specific muscle volumes and patella tendon orientation measured using magnetic resonance imaging (MRI). Participants demonstrated a decrease in peak anterior tibial shear forces (11.1 ± 3.3 vs. 9.6 ± 2.7 N · kg^?1; P = 0.008) and peak tibiofemoral compressive forces (68.4 ± 7.6 vs. 62.0 ± 5.5 N · kg^?1; P = 0.015) post-training. The decreased peak anterior tibial shear was accompanied by a decrease in the quadriceps anterior shear force, while the decreased peak compressive force was accompanied by decreased ground reaction force and hamstring forces. Our data provide justification for injury prevention programmes that encourage greater hip and knee flexion during landing to reduce tibiofemoral joint loading.     

Psychometric Properties of a Parental Questionnaire for Assessing Correlates of Toddlers’ Physical Activity and Sedentary Behavior

This study examined the psychometric properties of a questionnaire developed with the guidance of the socialization model of child behaviour to understand modifiable correlates of toddlers’ physical activity and sedentary behaviour. Findings are based on 118 parents (33.7 ± 4.9 years; 86% female) of toddlers (19.3 ± 2.7 months; 48% female) from Edmonton, Canada in The Parents’ Role in Establishing healthy Physical activity and Sedentary behaviour habits study (PREPS). The PREPS questionnaire encompassed 21 variables across the constructs of the socialization model of child behaviour. Of the nine variables assessed for internal consistency reliability, eight had good (α ≥ 0.70) reliability. Of the 15 continuous variables assessed for 1-week test–retest reliability, 10 had moderate (intra-class correlation = 0.50–0.74) and 5 had good (intra-class correlation ≥ 0.75) reliability. Of the six categorical variables assessed for 1-week test–retest reliability, two had fair (К = 0.21–0.40), one had moderate (К = 0.41–0.60), one had substantial (К = 0.61–0.80), and two had almost perfect (К = 0.81–1.00) reliability. Of the 12 sedentary behaviour variables assessed for convergent validity, 7 were significantly correlated with children’s screen time, of which three were small (r ≤ 0.29), two were medium (r = 0.30–0.49), and two were large (r ≥ 0.50) effect sizes.     

A case study of the diversity culture of an American university athletic department: perceptions of senior level administrators

The topic of diversity has received considerable attention from scholars who study sport within the context of higher education in the USA. But despite this interest in the topic, an in-depth focus on how college and university athletic departments effectively manage diversity is missing from the literature. Therefore, we conducted an intrinsic case study of an American university athletic department in efforts to highlight its unique diversity culture (i.e. how it creates and sustains a culture of diversity and inclusion) and the potential impact this culture could have on its various educational stakeholders, and how they interact in this organizational or workplace setting. Findings from our qualitative case study with senior level administrators uncovered two major interrelated themes. First, this institution of higher education has a history and culture of valuing diversity, and this in turn has positively impacted the athletic department's commitment to diversity. Second, the integration of the athletic department into the broader university culture, particularly because of its organizational structure, has enabled this department to better embrace diversity and avoid some of the educational challenges many of its peers face. Research and practical implications are discussed in this study.     

Dispositions of elite-level Australian rugby coaches towards game sense: characteristics of their coaching habitus

Bourdieu's analytic concept of habitus has provided a valuable means of theorising coach development but is yet to be operationalised in empirical research. This article redresses this oversight by drawing on a larger study that inquired into how the ‘coaching habitus’ of elite-level Australian and New Zealand rugby coaches structured their interpretation and use of the Game Sense approach to coaching to illustrate how habitus can be operationalised. It focuses on the identification of characteristics of the individual coaching habitus of four elite-level Australian rugby coaches and how they shape their interpretation and use of Game Sense. Drawing on suggestions made by Lau, we identify the characteristics of four individual ‘coaching habitus’ by examining their views on: (1) the characteristics of good coaches; (2) characteristics of great rugby players and how to develop them; and (3) their dispositions towards innovation in coaching.     

Does extensive on-water rowing increase muscular strength and endurance?

The purpose of this study was to compare changes in aerobic condition, strength, and muscular endurance following 8 weeks of endurance rowing alone or in combination with weight-training. Twenty-two elite rowers were assigned to (1) rowing (n = 10, 250-270 km · week?1) or (2) rowing (n = 12, 190-210 km · week?1) plus four weight-training sessions each week. Pre and post mean and standardized effect-size (ES) differences in aerobic condition (watts at 4 mmol · L?1) and strength (isometric pull, N), prone bench-pull (6-repetition maximum, 6-RM), 5- and 30-repetition leg-press and 60-repetition seated-arm-pull (J, performed on a dynamometer) normalized by body mass and log-transformed were analysed, after adjusting for gender. The standardized differences between groups were trivial for aerobic condition (ES [±90% CI] = 0.15; ±0.28, P = 0.37) and prone bench-pull (ES = 0.27; ±0.33, P = 0.18), although a moderate positive benefit in favour of rowing only was observed for the seated-arm-pull (ES = 0.42; ±0.4, P = 0.08). Only the weight-training group improved isometric pull (12.4 ± 8.9%, P < 0.01), 5-repetition (4.0 ± 5.7%, P < 0.01) and 30-repetition (2.4 ± 5.4%, P < 0.01) leg-press. In conclusion, while gains in aerobic condition and upper-body strength were comparable to extensive endurance rowing, weight-training led to moderately greater lower-body muscular-endurance and strength gains.     

Different types of compression clothing do not increase sub-maximal and maximal endurance performance in well-trained athletes

Abstract

Three textiles with increasing compressive surface were compared with non-compressive conventional clothing on physiological and perceptual variables during sub-maximal and maximal running. Fifteen well-trained endurance athletes (mean ± s: age 27.1 ± 4.8 years, [Vdot]O_2max 63.7 ± 4.9 ml · min^?1 · kg^?1) performed four sub-maximal (～70%[Vdot]O_2max) and maximal tests with and without different compression stockings, tights, and whole-body compression suits. Arterial lactate concentration, oxygen saturation and partial pressure, pH, oxygen uptake, and ratings of muscle soreness were recorded before, during, and after all tests. In addition, we assessed time to exhaustion. Sub-maximal (P = 0.22) and maximal oxygen uptake (P = 0.26), arterial lactate concentration (P = 0.16; 0.20), pH (P = 0.23; 0.46), oxygen saturation (P = 0.13; 0.26), and oxygen partial pressure (P = 0.09; 0.20) did not differ between the types of clothing (effect sizes = 0.00–0.45). Ratings of perceived exertion (P = 0.10; 0.15), muscle soreness (P = 0.09; 0.10) and time to exhaustion (P = 0.16) were also unaffected by the different clothing (effect sizes = 0.28–0.85). This was the first study to evaluate the effect on endurance performance of different types of compression clothing with increasing amounts of compressive surface. Overall, there were no performance benefits when using the compression garments.     

The Application of a Multiple Measurement Approach to Investigate the Effects of a Dance Program on Educable Mentally Retarded Adolescents

Abstract

Little evidence exists to assess the effects of dance training on special populations. Research in this field has relied on pretest-posttest methods for gathering data. While such data gathering methods may be appropriate for particular research problems, alone they may be inadequate for broad-based, exploratory investigations of programs and effects. The present study is an example of a multiple measurement approach that uses eight measurements, in combination, to answer four research questions regarding the physical and social effects that occur when a group of educable mentally retarded adolescents is exposed to a 10-week dance program. The findings revealed that four students showed improvement in both social and physical behaviors, seven students showed improvement in either social or physical behaviors, and two students showed no improvement. There was no evidence of a “transfer effect” due to participation in the program, and some students' behaviors were affected by external factors. The authors found the approach useful for identifying multiple effects and generating hypotheses for further study.     

Book reviews

Zwartjes, Otto, ed. La Sociedad andalusí y sus tradiciones literarias (Foro Hispánico, 7). Amsterdam: Rodopi, 1994.

Brincat, Joseph M. Malta 870–1054: Al‐Himyai's Account and its Linguistic Implications. Malta: Said International Ltd., 1995. 52pp.

Sells, Michael A. Mystical Languages of Unsaying. Chicago: The University of Chicago Press, 1994. 316 pp., US$18.95 (paperback), US$49.91 (cloth).

Diem, Werner, Arabische Geschäftsbriefe des 10. bis 14. Jahrhunderts aus der Österreichischen Nationalbibliothek in Wien (Documents Arabica Antiqua 1), 2 vols. Wiesbaden: Harrassowitz, 1995. Textband ix+518pp., Tafelband 76 plates.

Coope, Jessica A. The Martyrs of Cordoba: Community and Family Conflict in an Age of Mass Conversion. Lincoln: University of Nebraska Press, 1995. xvii+113 pp., US$ 25 (cloth).

Edwards, John. Religion and Society in Spain, c.1492 (Variorum Collected Studies Series: CS 520). Aldershot and Brookfield: Variorum, 1996. x+351 pp., US$ 97.00 (cloth).

Tolan, John Victor, ed. Medìeval Christian Perceptions of Islam. A Book of Essays (Garland Medieval Casebooks, Volume 10). New York and London: Garland Publishing, 1996. xxi+414 pp., US$60.00 (cloth).