HEIKKI KYRÖLÄINEN 1 , MATTI SANTTILA2 1National Defense University, Helsinki, Finland; 2Department of Biology of Physical Activity, University of Jyväskylä, Finland, 3Training Division of Defense Command, Helsinki, Finland. Good levels of both aerobic and neuromuscular fitness are of great importance in order to ensure sufficient physical performance of soldiers. However, it is well-known that physical fitness, especially, cardiovascular fitness of adolescents has decreased by 8-12 % during the last 2-3 decades (e.g. Dyrstad et al. 2005; Santtila et al. 2006; Knapik et al. 2006). Leyk et al. (2006) have studied more than 58000 applicants for the German Bundeswehr. They have found that failure rates of the male volunteers had significantly increased since 2001 and more than 37 % of the participants failed to pass the PFT. Changes in neuromuscular fitness seem, however, to be controversy. Knapik et al. (2006) have reviewed that muscle strength has increased among US Army recruits between 1978 and 1998. In a population-based study, muscle fitness has decreased but later than aerobic fitness (Santtila et al. 2006). In the present study, we have compared laboratory and field tests performed in military environment. Direct bicycle ergometer or treadmill running tests have been used as golden standard measurements of maximal aerobic capacity (peakVO2 or VO2max), while predicted VO2max measurements are based on the assumption that there is a linear relationship between heart rate and VO2 (Åstrand et al. 1954). On the other hand, muscle strength and endurance are also important factors in many activities of soldiers. In our VO2max studies by a bicycle ergometer, the initial work load was 50 W. It was increased by 25 W every second minute until exhaustion (MILFIT/FitWare, AinoActive Oy, Helsinki, Finland). VO2 was measured continuously using a gas analyzer (SensorMedics, Yorba Linda, California, USA). Heart rate was recorded continuously by a heart rate monitor (Polar Electro, Kempele, Finland). In neuromuscular tests, bilateral isometric maximal strength of the arm and leg extensors, grip strength, and muscle endurance (recording of the number of repetitions in one-minute push-up, sit-up and squat actions) were utilized. VO2max measured indirectly and directly correlated significantly (r=0.80-0.84, p<0.001) with each other. The absolute and relative differences between the methods varied from -0.4 to 1.3 ml-1·kg-1·min-1 and from 0.9 to 2.7 %, respectively. Significant correlations were also found between maximal strength of the arm extensors and repeated push-ups (r = 0.58, p < 0.001) as well as between repeated squats and VO2max (r = 0.55, p < 0.001). No significant relationships were observed between maximal isometric strength of the arm or leg extensors and that of VO2max. The present predicted VO2max measurements only slightly over- or underestimated the VO2max values of the direct measurements. Therefore, it can be concluded that our protocol is fairly accurate and valid to predict VO2max values in male subjects. Nevertheless, in a large group of subjects with great interindividual variation in physical fitness, the muscle endurance tests such as push-ups, sit-ups and repeated seem to measure not only the level of muscle endurance, but also to some extent that of maximal strength. The relationship between maximal strength and muscle endurance was found in push-ups but not in repeated squats. However, the performance in repeated squats was related with VO2max, whereas that of push-ups did not. In conclusion, the present muscle fitness tests seem to measure rather well the overall fitness profile of soldiers, and the contributive role of maximal strength could be indentified for the arm but not for leg extensor muscles. References:
|
||||||||
Conseil International du Sport Militaire © CISM | Design CISM Media | webmaster@cism-milsport.com |