Introduction to Sports Biomechanics: Analysing Human Movement ...

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Walking MOVEMENT PATTERNS – THE ESSENCE OF SPORTS BIOMECHANICS those of another person; indeed, the movement patterns from repetitions of that task by the same individual will also vary – this becomes more obvious when we quantitatively analyse those movements, but can be seen qualitatively in many patterns of movement, as in Chapter 3. These variable responses, often known as movement variability, can and do affect the way that movement analysts look at sports movements. The qualitative descriptions in the following sections will not, therefore, apply to every adult, but will apply to many so-called ‘normals’. The developmental patterns of maturing children up to a certain age show notable differences from those for an adult, as in Figures 1.12 and 1.18 below. A first step in the analysis of a complex motor skill is often to establish the phases into which the movement can be divided for analysis. For example, the division of a throwing movement into separate, but linked, phases is useful because of the sheer complexity of many throwing techniques. The phases of the movement should be selected so that they have a biomechanically distinct role in the overall movement, which is different from that of preceding and succeeding phases. Each phase then has a clearly defined biomechanical function and easily identified phase boundaries, often called key events. Although phase analysis can help the understanding of movement patterns, the essential feature of all sports movements is their wholeness; this should always be borne in mind when undertaking any phase analysis of a movement pattern. Walking is a cyclic activity in which one stride follows another in a continuous pattern. We define a walking stride as being from touchdown of one foot to the next touchdown of the same foot, or from toe-off to toe-off. In walking, there is a single-support phase, when one foot is on the ground, and a double-support phase, when both are. The single-support phase starts with toe-off of one foot and the double-support phase starts with touchdown of the same foot. The duration of the single-support phase is about four times that of the double-support phase. Alternatively, we can consider each leg separately. Each leg then has a stance and support phase, with similar functions to those in running (see pages 15–23). In normal walking at a person’s preferred speed, the stance phase for one leg occupies about 60% of the whole cycle and the swing phase around 40% (see, for example, Figure 1.7). In normal walking, the average durations of stance and swing will be very similar for the left and right sides. In pathological gait, there may be a pronounced difference between the two sides, leading to arrhythmic gait patterns. The book’s website contains many video clips of side and rear views of people walking. These illustrate differences between males and females, between young and older adults and young children, between overground and treadmill locomotion and at different speeds and treadmill inclines, and with various types of footwear. Figures 1.7 to 1.12 contain still images from a selection of these video clips. Observing these figures, you should note, in general, the following patterns of flexion and extension of the hip, knee and ankle; you should also study the video sequences on the book’s website to become familiar with identifying these movements on video. The hip flexes 9
INTRODUCTION TO SPORTS BIOMECHANICS Figure 1.7 Young female walking overground at her preferred speed in trainers. Top left: left foot touchdown (0 s); top right: right foot toe-off (0.12 s); middle left: left foot mid-stance; middle right: right foot touchdown (0.52 s); bottom left: left foot toe-off (0.64 s); bottom right: right foot mid-stance. 10 during the swing phase and then begins to extend just before touchdown; extension continues until the heel rises just before toe-off. The hip then starts to flex for the next swing phase, roughly when the other foot touches down. The knee is normally slightly flexed at touchdown and this flexion continues, although not necessarily in slow walking. Some, but not much, extension follows before the knee starts to flex sharply immediately after the heel rises; this flexion continues through toe-off until about
Page 2: Introduction to Sports Biomechanics
Page 5 and 6: First edition published 1997 This e
Page 8 and 9: Contents List of figures x List of
Page 10 and 11: Study tasks 216 Glossary of importa
Page 12 and 13: FIGURES 1.26 Underarm throw - femal
Page 14 and 15: FIGURES 5.9 Typical path of a swimm
Page 16 and 17: Tables 2.1 Examples of slowest sati
Page 18 and 19: Preface Why have I changed the cove
Page 20 and 21: Introduction MISSING TEXT The first
Page 22: INTRODUCTION principal movements in
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Page 31: INTRODUCTION TO SPORTS BIOMECHANICS
Page 69 and 70: Figure 2.2 ‘Principles’ approac
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INTRODUCTION TO SPORTS BIOMECHANICS
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Figure 2.13 Identifying critical fe
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Figure 6.8 Main skeletal muscles: (
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INDEX 282 balls air flow past 173 b
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INDEX 284 energy 219 kinetic 219 mi
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INDEX 286 isokinetic contraction 24
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INDEX 288 muscle length-tension rel
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INDEX 290 three-dimensional 146-7,
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INDEX 292 validity 220 vantage poin
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