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.     

A season-long team-building intervention: examining the effect of team goal setting on cohesion

The purpose of the current study was to determine whether the implementation of a season-long team-building intervention program using team goal setting increased perceptions of cohesion. The participants were 86 female high school basketball players from 8 teams. The teams were randomly assigned to either an experimental team goal-setting or control condition. Each participant completed the Group Environment Questionnaire (GEQ; Carron, Brawley, & Widmeyer, 2002; Carron, Widmeyer, & Brawley, 1985), which assessed cohesion at both the beginning and end of the season. Overall, the results revealed a significant multivariate effect, Pillai's trace F(12, 438) = 2.68, p = .002. Post hoc analyses showed that at the beginning of the season, athletes from both conditions did not differ in their perceptions of cohesion. However, at the end of the season, athletes in the team goal-setting condition held higher perceptions of cohesion than athletes in the control condition. Overall, the results indicated that team goal setting was an effective team-building tool for influencing cohesiveness in sport teams.     

Reviews

Pat Sadler, Hiroshima Shudo University, The Caring Child by Nancy Eisenberg. Cambridge, Mass, and London: Harvard University Press, 1992, hb ISBN 0 674 09725 4, pb ISBN 0 674 09726 2, US$8.95

Garry Hornby, University of Hull, Youth in Trouble: Educational Responses, by J. F. Schostak. London: Kogan Page, 1991. 192pp., pb. ISBN 0 7494 0372 1, np

Gordon Dimmock, Harold Hill Community School, Havering, ‘Some Way to Go’: A Pilot Study on the Appraisal of Educational Resources on Leaving Home and Homelessness, Leaving Home Project. London: Information Services Charity Limited, 1987. 56pp., £4.95

Gordon Dimmock, Harold Hill Community School, Havering, Experimental Project. Final Report, Leaving Home Project. London: Information Services Charity Limited, 1991. 30pp., £6

Gordon Dimmock, Harold Hill Community School, Havering, ‘Making the Break’: Choices and Decisions Facing Young People Leaving Home, by Philip Hope, edited by Catherine ByGott. London: CSV Advisory Service and Leaving Home Project, 1989. 157pp. plus VHS video ‘Cutting Loose’, 20 min., CSV, 1988. ISBN 0 907829 57 0, £28.25+£2.40 p. & p.

Don Baines, Anglia Polytechnic University, Teacher Training in Secondary Schools, by Rowie Shaw. London: Kogan Page Limited, 1992. 162pp., pb ISBN 0 7494 0637 2, £14.95

Gill Collins, Sovereign Centre Tutorial Unit, Issues: A Cross-Curricular Course for PSE, by John Foster. Hammersmith: Collins Educational, 1992. Pupil Book One, ISBN 0 00 327334 2, £4.95; Teachers Resources One, ISBN 0 00 327339 3, £7.25; Pupil Book Two, ISBN 0 00 327335 0, £4.95; Teachers Resources Two, ISBN 0 00 327340 7, £7.25; Pupil Book Three, ISBN 0 00 327336 9, £4.95; Teachers Resources Three, ISBN 0 00 3273415, £7.25; Pupil Book Four, ISBN 0 00 327337 7, £5.50; Teachers Resources Four, ISBN 0 00 327342 3, £7.95; Pupil Book Five, ISBN 0 00 327338 5, £5.50; Teachers Resources Five, ISBN 0 00 327343 1, £7.95