Application of 2-dimensional video analysis by competitive swimming coaches to monitor fatigue in breaststroke technique during training
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Thow2016.docx (3.282Mb)
Date
01/07/2016Author
Thow, Jacqueline Laura
Metadata
Abstract
In swimming, technical performance is a vital indicator of successful performance;
however, during phases of high-intensity training, technique can be negatively
influenced by fatigue. Advances in video technology have made it possible to increase
coaches’ capacity to monitor athletes’ technical performances during training. Yet
research examining the biomechanical responses that occur with fatigue using video
methods, which are applicable and relevant to coaches during training, is scarce. The
limited research to date that has examined the biomechanical responses that occur with
fatigue has been restricted to examining fatigue during race-like situations and have
used technology which is not available for use by coaches during training. Whilst this
research indicates that changes occur during races, it does not apply to coaches for use
during training. As fatigue, and its management, is a vital component of the training
process, identifying a method of monitoring fatigue during training, which is applicable
to coaches, is essential for athlete development. This research is therefore intended to
address this by exploring the implications of 2-dimensional (2-D) video analysis in the
management of fatigue, during training, by competitive swimming coaches.
To explore this, this thesis comprises of four studies. The aim of the first study was to
investigate whether 2-D video analysis methods currently used by coaches can measure
data validly and reliably. To achieve this, the accuracy, precision, reliability and validity
of thirty-five variables (thirty-four technical measures and swim time) were calculated
using Dartfish Pro Suite motion analysis software, version 6.0 (Dartfish Ltd, Fribourg,
Switzerland) and compared to the smallest worthwhile change. By calculating and
comparing these measures, only those technical variables which can be measured with
accuracy and precision could be determined objectively. A series of fifteen variables
(fourteen technical measures and swim time) were found to be precise, valid and reliable
when measured using Dartfish Pro Suite motion analysis software, version 6.0.
Using the previously established technical measures, the aim of the second study was to
assess if these measures can determine whether technical changes can occur during a
high-intensity training session. To achieve this, a group of seventeen elite breaststroke
swimmers completed a standard swim set. This involved repeating maximal effort 100m
swims on a limited swim-rest time, designed to induce a fatigued state representative of
high-intensity training conditions. To determine whether technical changes as a result of
fatigue could be detected, the fourteen kinematic technique variables and swim time
(fifteen dependent variables in total) were recorded and analysed using 2-D Dartfish Pro
Suite motion analysis software, version 6.0 from video recordings of the first and last
100m swim of each swimmer. In addition, 95% confidence intervals were determined to
investigate any commonalities or individual differences among swimmers in changes in
technical parameters. It was found that during one high-intensity session, technical
changes can occur in a group of elite swimmers. The largest changes were shown in leg
glide duration (64.6%), swim time (33.2%), stroke rate (35.3%), stroke length (-29.2%),
and average velocity (-10.2%) and were shown to have statistically significant (p < 0.05)
differences between the first and last 25m of the swim set. These changes were also
shown to be common amongst all swimmers and occurred early in the swim set.
To evaluate coaches understanding of fatigue and its management during training, the
aim of the third study was to assess coaches’ current practices and knowledge regarding
fatigue during training. To achieve this, a questionnaire was distributed to over 370
coaches throughout the UK. The questionnaire was separated into multiple sections
which assessed: coaches’ current understanding of the topic of fatigue; the methods
coaches’ employ to monitor fatigue during a training session; and the processes used to
manage fatigue during the training process. It was found that up to 98% of the coaches
consider fatigue, its effect and management important in the development of their
swimmers. Despite this, there is a lack of consistency in knowledge and methods used by
coaches to monitor this. As a result, coaches are continuing to use traditional methods to
monitor their athletes which are quick and reliable, specifically stopwatches (100%) and
visual observation (98%).
Due to the predominant use of visual observation to monitor fatigue, and the
identification of technical changes with fatigue, the aim of the fourth study was to assess
whether coaches could visually identify changes in the previously established technical
markers and whether this could be improved through education of fatigue and video
analysis methods. To achieve this, two groups of ten competitive swimming coaches
observed a series of videos of three swimmers taken pre- and post- training, and were
asked to identify any technical factors which they perceived to change. One group
underwent an intervention using Dartfish Pro Suite motion analysis software, version
6.0 and underwater analysis to assess whether this improved their ability to visually
observe fatigue in elite swimmers. The remaining group of coaches acted as a control
group and received no feedback. Following the one hour intervention, the coaches’
observations slightly improved, however this improvement was not statistically
significant (p > 0.05) nor retained after 4 weeks. Although the coaches’ perceptions of
fatigue during training varied, they did show a keen interest in further training and
education on fatigue and 2-D video analysis.
The results from this research indicate that 2-D video analysis is an effective and useful
tool, which has practical applications: in monitoring fatigue during a training session;
guiding training programmes to maximise training potential; and developing coaches’
identification and management of fatigue during training through education
programmes.