For many decades, cinematography was the most popular measurement technique for those involved in the analysis of human motion. Cine cameras have traditionally been considered superior to video cameras because of their much greater picture resolution and higher frame rates. However, over the last decade, considerable advances have been made in video technology which now make video an attractive alternative to cine.
Modern video cameras are now able to deliver excellent picture quality (although still not quite as good as cine) and high-speed models can achieve frames rates at least comparable to high-speed cine cameras. Unlike cine film, most video recording involves no processing time and the recorded images are available for immediate playback and analysis. Video tapes are very inexpensive when compared to the high cost of purchasing and processing of cine film.
The significant improvements made in video camera technology, coupled with a substantial fall in price of the hardware over the past decade, has led to cine cameras becoming virtually redundant in sport and exercise biomechanics. Video recordings of sport and exercise activities are usually made by biomechanisms in order to undertake a detailed analysis of an individual’s movement patterns.
Although on-line systems (Chapter 3) provide an attractive alternative to video, as a method of capturing motion data, video motion analysis has a number of practical advantages over on-line motion analysis including:
Low cost – video analysis systems are generally considerably cheaper than on-line systems.
- Minimal interference to the performer – video analysis can be conducted without the need for any disturbance to the performer, e.g. attachment of reflective markers. MOTION ANALYSIS USING VIDEO 9
- Flexibility – video analysis can be used in environments where some on-line systems would be unable to operate effectively, e.g. outdoors, underwater, in competition.
- Allows visual feedback to the performer – video cameras provide a permanent record of the movement that can be viewed immediately. On-line systems do not generally record the image of the performer.
Given the advantages listed above, video analysis will remain, for the foreseeable future, an important method of analyzing technique in sport and exercise. Video analysis of a person’s technique may be qualitative or quantitative in nature. Qualitative analysis involves a detailed, systematic and structured observation of the performer’s movement pattern. The video image is displayed on a TV monitor or computer screen and observed in real-time, slow motion and frame-by-frame.
Often, multiple images, e.g. front and side views, are displayed simultaneously to allow a more complete analysis to be undertaken. The purpose of this type of analysis is often to establish the quality of the movement being observed in order to provide some feedback to the performer