2007, Piran, Slovenia

Occupational Thermal Problems
PHYSICAL PERFORMANCE CAPACITY DURING 12 DAYS
MILITARY MANOEUVRE IN WINTER CONDITIONS
Juha Oksa 1 , Sirkka Rissanen 1 , Ossi Keskinen 2 , Heikki Kyröläinen 2 , Tero Mäkinen 1 , Matti
Santtila 3 , Ari Peitso 4 , Hannu Rintamäki 1, 5 ,
1 2
Finnish Institute of Occupational Health, Oulu, Finland, University of Jyväskylä,
Department of Biology of Physical Activity, Jyväskylä, Finland, 3 Training Division of the
Defence Staff, Helsinki, Finland, 4 Center for Military Medicine, Lahti, Finland, 5 University
of Oulu, Department of Physiology, Oulu, Finland
Contact person: juha.oksa@ttl.fi
INTRODUCTION
In military manoeuvres, soldiers are often exposed to various stresses such as prolonged and
strenuous physical exercise combined with sleep, energy and fluid deficiency, extreme
ambient temperature and time pressure. During prolonged manoeuvres, cardiovascular and
respiratory capacities, energy metabolism and neuromuscular performance may limit physical
performance (Nindl et al. 2002). However, the knowledge of the effects of long-term military
manoeuvres on the above mentioned factors is sparse. Therefore, the purpose of this study
was to investigate whether a long-term (12 days) military manoeuvre affects soldiers'
neuromuscular and cardiovascular performance in winter conditions.
METHODS
Twenty-three male joggers participated in this study ((mean ±SD): age 19.7 ±0.7 y, height
176.4 ±6.8 cm, body mass 71.5 ±9.9 kg, body fat 14.0 ±2.6%). Prior to participation all
subjects were briefed on the nature of the study and they gave a written consent to act as
voluntary subjects. Each subject participated three times in neuromuscular and cardiovascular
performance tests. The tests were carried out three days before the manoeuvre (T1), at the 5th
day of the manoeuvre (T2) and at the 12th day of the manoeuvre (after a 6-days shooting
training period) (T3). Body mass and amount of subcutaneous fat was measured during each
test. Six neuromuscular performance tests were performed. Maximal voluntary isometric leg
extension (LE) at the knee angle of 120° was performed in a seated position using leg
extension dynamometer and strain gauge (Hur leg extension/curl, Hur Ltd, Finland and
Newtest 200, Newtest Ltd, Finland). Static jump (SJ), counter movement jump (CMJ) and
drop-jump (DJ) (40-cm bench) were performed on a contact mat (PowerTimer, Newtest Ltd,
Finland). Rising heights of the body centre of gravity of the jumps were calculated by the
measured flight time, while anaerobic power (AP) was calculated by five consecutive CMJs
(Bosco et al. 1983). Maximal isometric rotation of the wrist (WR) was performed by twisting
a key, fixed to a strain gauge dynamometer (rotation dynamometer, Newtest Ltd, Finland),
using a thumb and two fingers (index and middle). Two maximal trials were performed in
each test, and the best result was taken for further analysis. To assess cardiovascular
performance capacity a maximal oxygen consumption test (maxVO2) on a bicycle ergometer
(Ergoline 100, Ergoline Gmbh, Germany) was performed. Similarly as neuromuscular tests
the test was carried out at the same time points T1, T2 and T3 as described above. During the
test external load (starting from 75 W) was increased by 25 W every two minutes until
exhaustion. Oxygen consumption (Metamax 3B, Cortex Biophysik Gmbh, Germany) and
heart rate (Polar 810, Polar Electro Ltd, Finland) were measured continuously and maximal
work load each subject was able to reach was recorded. From the data maximal oxygen
consumption (maxVO2), ventilation (VE), work load (WL) and heart rate (HR) was analysed.
All the tests were performed in a random order but taking care that before maxVO2 test there
was sufficient recovery time (at least 30 minutes) from previous test(s).
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