ABSTRACT
4 males and 1 female participated in 2 experimental trials randomised and administrated in
a cross over manner separated by 7 days to study the effects of skimmed milk as a
re-hydration source compared to water. The experiment lasted 30 minutes and the
participants cycled at 70% of their heart rate max. Both attended the lab in a 3 hour fasted
state apart from 900ml water 60 minutes before attending. The participants body mass was
measured pre and post exercise, urine samples were taken before and straight after testing,
measuring the amount and urine osmolality, a blood sample was also taken before and
straight after, measuring the blood haematocrit (%). Heart rate, rate of perceived exertion
(RPE) and skin temperature were all measured pre exercise, at 10, 20 and 30 minutes and
post exercise. 100 ml of skimmed milk or water were consumed at pre exercise, at 10, 20
and 30 minutes also. Results show that when subjects ingested milk, their
KEY WORDS: Osmolality, Haematocrit, Rate of perceived exertion, Re-hydration.
INTRODUCTION
Research into re-hydration is extensive, however, the solutions used have been designed in
laboratories, rather than researching drinks that are found in the home (Saat 2002) such as
milk. Milk is similar to many sports drinks as its carbohydrate and electrolyte content is
high, making it a potentially effective re-hydration solution.
Water accounts for 45 – 70% of body weight, around eight stone of water in an average 11
stone adult, and the loss of a small fraction of this water could significantly decrease
performance (Sawka 1998). Two thirds of the water in the human body is intracellular, in
muscle tissue, with the remaining one third is extra cellular, found in spaces in-between
cells, lymph and blood plasma (Fink 2006). Dehydration reduces the bloody plasma level,
reducing blood volume and increasing blood viscosity, slowing down circulation and
reducing the amount of oxygen delivered to the working muscles (Van Essen 2006).
Water has excellent conductive properties and helps lower core temperature in athletes, as
it conducts heat twenty six times faster than air (Fink 2006).Core temperature is the
temperature of the deep tissues of the body, usually measured orally or rectally (Williams
2005). Saats research in 2002 also highlighted that water helps in regulating the body’s pH
levels, as it carries protein buffers like haemoglobin, directly helping to neutralise lactic
acid. This is vital in an athlete, helping to prevent the build up of lactic acid, which can
