european college of sport science

Saturday, June 27th, 2009
EFFECT OF SHORT-TERM SUPPORTLESSNESS UPON PERFORMANCE OF LOCOMOTION TEST WITH VOLUNTARY ION OF
SPEEDS AT A STABLE AND UNSTABLE TREADMILL
VINOGRADOVA, O., VORONOV, A., POPOV, D., FOKIN, K., TRUSHEVA, T., KOZLOVSKAYA, I.
INSITUTE FOR BIOMEDICAL PROBLEMS
INTRODUCTION: Step-wise locomotion test with voluntary selection of speeds is used for evaluation of physical fitness in a Russian system
of counter measures for preserving health and efficiency of cosmonauts under unfavorable conditions of microgravity. Test consists of 4
steps with rising intensity at a passive treadmill. Speed at each step is selected by the subject individually according to following wording:
walking, jogging, moderate running, fast running. The duration of each step and friction of a treadmill are fixed. According to the technical
requirements for International Space Station equipment the treadmill is to be vibro isolated from the body of the Station, that is the
treadmill is unstable.
The aim of the study was to evaluate the efficacy of locomotion exercise at the unstable treadmill under control conditions and after 6
hours of “dry immersion” (head-out water immersion with waterproof fabric separating subject from water) mimicking the conditions of
supportlessness.
METHODS: 8 healthy young male subjects gave their informed consent to participate in a study. They performed test at the stable and
unstable treadmill both under control conditions and after 6-hours dry immersion.
RESULTS AND DISCUSSION: Total way covered by a subject during test was significantly lower at unstable treadmill than at stable. After
dry immersion the total way covered at a stable treadmill did not change and at an unstable treadmill – decreased. Under control conditions
maximal running speed at the unstable treadmill in comparison with stable was unchanged and after immersion was decreased.
Sensation of the perceived exertion during test did not change in all cases except one. It is understandable as the test is organized in
such a way that the subject is choosing the speeds according to his perceived exertion. The impact loads significantly decreased at an
unstable platform apparently because of damping. After dry immersion impact loads at the stable treadmill did not affect, but significantly
enforced at an unstable treadmill.
Energy cost of exercise was evaluated as an increase of energy consumption in response to an increase of locomotion speed during
jogging-running part of the test. Energy cost of locomotion had a tendency for an increase during exercise at an unstable treadmill. After
immersion the energy cost of exercise at unstable treadmill increased both in comparison with the cost at stable and unstable treadmill.
EMG-activity of m. soleus and m. rectus femoris increased during exercise at unstable treadmill. That means maintenance of vertical
posture became more difficult. After immersion activity was redistributed between different muscles.
CONCLUSION: Thus changes in energy cost of exercise at unstable treadmill and after immersion may be connected with redistribution
and increase of activity for different muscle groups under conditions of unstability and as a result of short-term period of supportlessness.
14:15 - 15:15
Poster presentations
PP-PH14 Physiology 14
THE EFFECT OF NAHCO3 INGESTION ON POWER OUTPUT DURING EXERCISE AT A CONSTANT LEVEL OF PERCEIVED
EXERTION.
RENFREE, A.
UNIVERSITY OF WORCESTER
Manipulation of acid-base status has been demonstrated to influence RPE during exercise (Kostka & Cafarelli 1982), suggesting that shifts
in blood [H+] are linked to sensory processes. Ingestion of NaHCO3 has been demonstrated to reduce RPE during supra lactate threshold
(>LT) intensity exercise (Robertson et al 1986) indicating that ingestion could also result in increased muscular power output during exercise
at similar RPE’s. The purpose of this study is therefore to investigate the effect of NaHCO3 ingestion on power output during cycling at
an RPE associated with >LT exercise.
Ten recreationally active male participants (26+2.4 years) performed an incremental exercise test on an electronically braked cycle ergometer
for identification of LT and RPE at a range of submaximal workloads using the Category Ratio Scale (Borg 1982). Participants
performed four further experimental trials, two at an RPE associated with >LT exercise, and two at an RPE associated with