Scientific Method of Problem Solving • Develop (define and delimit) the problem • Formulate the general hypothesis: • Overload training improves strength • (e.g., 3 sets of bp 3 d/w will improve bp strength) • Formulate the specific hypothesis: • If A (general) is true, then B (specific) will be true • (e.g., if the general hyp is true, then posttest > pretest) • Gather , analyze, and interpret the data • If B is true (significant difference), what about A? • If B is not true (no sig diff), what about A? • Discuss the results • Is B without A very unlikely, or are there alternative explanations?
Sport biomechanics – outline • Reading assignments: • Kreighbaum & Barthels – Module J (pp 335-353, Ch 11 (pp 370-384), esp pp 372-375 on baseball pitch • Adrian – Ch 17, esp pp 333-339, Ch 18, esp 365-369 • Review Welch paper in JOSPT on baseball hitting (see questions related to this article on last slide) • Review Harms and Noble paper on warmup and bat velocity (specific summary assignments) • Review Nicholls and Elliott paper in JAB on bat kinematics (specific summary assignments)
Biomechanical correlates of participation in sports:areas of interest and effort • Evaluate process – technique – optimize efficiency, or outcome • Injury potential/prevention • How to enhance acquisition of sport skills– motor learning • Design appropriate conditioning programs to enhance performance • Equipment Design and Selection • ground-foot interfaces • protective equipment (pads, gloves, head gear) • striking implements • balls • Sports playing surfaces
Exercise and Sport Biom Prof Org • American College of Sports Medicine • International Society of Biomechanics in Sports • Biomechanics academy of AAHPERD • North American Society of Biomechanics • International Association for Sports Surface Sciences • International Society of Biomechanics • American society of Biomechanics • Canadian Society of Biomechanics • European Society of Biomechanics • Formosan Society of Biomechanics • International Sports Engineering Association • International Shoulder Group • ISB Technical Group on the 3-D Analysis of Human Movement. • European Society for Movement Analysis in Adults and Children • ca/biomechanics/
Sport biomechanics journals • Research quarterly for exercise and sport • Medicine and science in sport and exercise • Journal of applied biomechanics • Sports biomechanics • International journal of sport and health science • Journal of sports sciences • Sports engineering • Pediatric exercise science • Journal of orthpaedic and sport physical therapy • Journal of biomechanics • Journal of athletic training • Journal of strength and conditioning research • Journal of electromyographic kinesiology • Sports medicine
Throwlike and Pushlike Movement Patterns • Usual objectives of throw and push patterns • projection of objects for greatest horiz or vert dist • ex : javelin, discus, shotput • projection of objects for accuracy with speed a factor • ex: volleyball, tennis, racquetball, baseball pitch • Movement pattern terminology review • Throwing patterns are further defined as underarm, sidearm, or overarm Skills listed under each pattern differ because of constraints • ex: rules governing implement or ball, rules governing target. • Open and Closed chain movements • Open kinetic chain - sequential segmental action, end segment isfreeto move (e.g., baseball pitch) • Closed kinetic chain - simultaneous end segment movement, end segment meets with “considerable resistance “ (e.g., shot put)
Throwlike and Pushlike Movement Patterns • Characteristics of throw-like patterns • can be a strike or a kick • high end-point velocity is critical • sequential segmental action, object lags behind elbow and/or shoulder • Open kinetic link model - Figure J.1, p 338; J.2, p 339 • Linear motion of a point on a rotating segment: V = r • Sequencing segmental rotations - kinetic link principle • system has a base and a free open end • segmental masses progressively decrease • an external torque is applied at the base to initiate the movement • segmental rotational acceleration is timed sequentially • A model of an open kinetic link system - Fig J.4, p 343 • Throwlike movements performed while in the air - Fig J.5, p 345
Phases of pitching: • Windup (a-k) • Early Preparation (l-m) • Late preparation (n-p) • Release (r-u) • From: Feltner, M. & Dapena, • (1986) Dynamics of • shoulder and elbow joints of • the throwing arm during a • baseball pitch. Int J Biomech • 235-259.
Javelin – similar To baseball pitch
Throwlike and Pushlike Movements • Pushlike patterns - Simultaneous segmental actions • Objective is accuracy, or large motive force • Distal segments move simultaneously, resulting in rectilinear movement of distal segment • Four differences in throw and push. In throws: • distal segment “lags back”, segments move sequentially, object moves curvilinearly, wheel-axle movements (shoulder and hip rotation) involved • Movements lie on a throw-push continuum, the location depending on constraints of performer and object: • performer strength and skill • object mass, size, and shape
Developmental stages of throwing • Stage 1- ball thrown primarily with elbow extension – no rotation of thorax or arm • Stage 2 - Thoracic rotation accompanies backward motion of the arm. The throw is initiated by the arm swing forward. Some arm rotation as well as forearm extension at various times • Stage 3 - step is taken with same side foot to initiate throw • Stage 4 – step is taken with contralateral foot, thoracic rotation, arm rotation, elbow extension
Side arm striking pattern: The baseball swing Stance Stride Swing Bat begins moving forward Lift front foot Follow-through Ball-bat impact
Questions related to Welch JOSPT paper on baseball hitting • What type of study was this? Experimental, correlational, or descriptive? • What is the purpose of the study? • What is the primary contribution of this study to the scientific or professional community? • To what conditions and subject populations can the results be applied? • What type of motion analysis system was used in the study? • Were the data collection and reduction methods (time and position resolution, synchronization methods, data smoothing procedures, etc.) adequate? • Which segments were included in the analysis related to the kinetic link principle? Were any relevant segments missing? • What three events separated the stance, stride, swing, and follow-through? • Were the findings consistent with the kinetic link principle? • Do you have any suggestions as to how the study could be improved?