Endurance athletes were divided into experimental
(n = 12) and control (n = 12) groups to investigate
the effects of extra-load training on energy metabolism
during exercise. A vest weighing 9%-10% body weight
was worn every day from morning to evening for 4
weeks including every (n = 6) or every other (n =
6) training session. After 4 weeks the control group
had a lower blood lactate concentration during submaximal
running, whereas the experimental group had significantly
higher blood lactate and oxygen uptake (p less than
0.01--p less than 0.05), and a lower 2 mmol lactate
threshold (p less than 0.05) and an increased blood
lactate concentration after a short running test
to exhaustion (p less than 0.05). Those experimental
subjects (n = 6) who used the added load during every
training session had a lower 2 mmol lactate threshold,
improved running time to exhaustion, improved vertical
velocity when running up stairs and an increased
VO2 during submaximal running after the added load
increased anaerobic metabolism in the leg muscle
during submaximal and maximal exercise. An increased
recruitment and adaptation of the fast twitch muscle
fibres is suggested as the principal explanation
for the observed changes.
