Dear all,
On Thursday 19th May, the RSS Leeds/Bradford local group will be
hosting two talks on "body shapes, body clocks and athletic performance".
The meeting will be held at Leeds Metropolitan University Carnegie
Pavilion, room CPV335, starting at 3pm with refreshments from 2.30pm.
Further details of the talks can be found on our webpage:
http://tinyurl.com/rss-lba
Best wishes,
Paul
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Dr. Paul D. Baxter
Secretary/Treasurer, RSS Leeds/Bradford Local Group,
Division of Biostatistics, University of Leeds, Leeds, LS2 9JT, UK.
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Leeds/Bradford: Thursday 19 May, 3.00pm, Leeds Metropolitan University.
Body shapes and body clocks in athletic performance
Alan Nevill (University of Wolverhampton)
Predicting the optimal body shape for health and physical performance
Human physique consists of three distinct but interrelated
anthropometric components, 1) body size, 2) body composition and 3)
structure or shape (Slaughter and Christ, 1995). Body size refers to the
physical magnitude of the body and its segments (stature, mass, surface
area, etc). Body composition consists of the amount of various
constituents in the body such as fat, muscle, bone, etc. Body structure
or shape describes the distribution of body parts expressed as ratios,
such as the body mass index (BMI= Mass / Height^2), the inverse ponderal
index = (Height/Mass^0.333) or the head length-to-body length (exclusive
of head) ratio. The later concept of shape was discussed by Mosimann
(1970), who defined the term shape as the ratio of two body dimensions
measured in the same units that would yield a `dimensionless` ratio
variable reflecting body shape. The curial index (simplistically defined
as the leg height below the knee divided by the leg height above the
knee) is a typical example.
The purpose of this talk is to outline a number of methods that can be
used to predict the optimal human body shape for a variety of health and
physical performance measures.
Greg Atkinson (Liverpool John Moores University)
Keeping athletes in time with their body clocks
Chronobiologists investigate time-dependent changes in physiological
variables. Circadian rhythms refer to variations that recur every 24
hours. Many circadian rhythms at rest are endogenously controlled,
persisting when an individual is isolated from environmental
fluctuations. Experimental studies on performance circadian rhythms need
to be carefully designed to control for serial fatigue effects and to
minimise disturbances in sleep. Observations of rhythmicity in
performance variables are also highly influenced by the degree of
repeatability of the measuring equipment.
The majority of the components of sports performance peak in the early
evening, close to the daily maximum in body temperature. Exceptions are
short-term memory, tasks demanding fine motor control, heart rate-based
tests of physical fitness and prolonged submaximal exercise carried out
in hot conditions which all peak in the morning. Athletes are advised to
schedule their heaviest training session in the evening, since higher
work-rates are selected spontaneously at this time of day. Athletes who
train only in the early morning are unlikely to reverse the evening
superiority of self-selected work-rates fully.
The normal circadian rhythms can be desynchronised following a flight
across multiple time-zones or during shift-work. Although athletes show
all the symptoms of "jet lag" (increased fatigue, disturbed sleep and
circadian rhythms), more research work is needed to identify the effects
of transmeridian travel on the actual performances of elite sports
competitors. Shiftwork interferes with participation in competitive
sport, although there may be greater opportunities for shiftworkers to
train in the hours of daylight for individual sports. Possible
interventions to "treat" these disruptions are bright light or exercise
itself. These and other aspects of the human body clock will be covered
in the lecture with particular emphasis on the time-series analyses that
are employed.
The meeting will be held at Leeds Metropolitan University Carnegie
Pavilion, room CPV335, starting at 3pm with refreshments from 2.30pm.
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