No abstract

The present findings demonstrate that neuromuscular performance can be relatively well maintained during short-term garrison and field training even when a clear decrease in hormonal profile is evident. In addition, hormonal responses during field training seem to be greater compared to garrison training, however, the recovery of 3-day in free-living conditions seems to be sufficient for hormonal recovery. Therefore, a short-term recovery period lasting few days after the military field training may be required to maintain operational readiness after the field training.

The autonomic nervous system and circulating hormones control a stress reaction through a complex interaction. We tested the hypothesis that changes in cardiac vagal regulation may be positively associated with the serum testosterone-to-cortisol ratio during the first week of military service in 24 conscripts aged 19.090.3 years. Cardiac autonomic function was assessed by measuring high-frequency (HF: 0.15Á0.4 Hz) and low-frequency (LF: 0.04Á0.15 Hz) power spectral indices of R-R intervals during supine rest and during a controlled standing condition (5 min for both) from the second to the seventh mornings at the beginning of military service. Blood samples were collected to analyse the basal serum testosterone-tocortisol ratio on the seventh morning. Changes in heart rate and high-frequency power measured in the standing condition were positively correlated with the serum testosterone-to-cortisol ratio at day 7 (r 0(0.42 and r00.45, respectively; P B0.05 for both). However, changes in low-frequency power and LF/HF ratio did not correlate with testosterone or cortisol concentration. The present results suggest a relationship between changes in cardiac vagal regulation during a longterm mentally stressful condition and the serum testosterone-to-cortisol ratio. This association was more marked during the controlled standing condition.

The purpose of the study was to examine how military training influences neuromuscular function in non-overreached and overreached conscripts. A total of 24 male conscripts participated in the study (8 weeks basic training+2 weeks specialized training). All measurements were conducted during weeks 1, 5, 8 and 10. After the training period, nonoverreached (NOR, n= 16) and overreached (OR, n= 8) groups were compared. Isometric maximal forces (bench press, elbow flexion and knee extension), single twitch (plantar flexors), H-reflex, M-wave (Hmax/Mmax) and V-wave (V/Mmax) (soleus) were measured.In knee extension, force production increased in NOR by 22.5±20.5% (p<0.01) between weeks 1 and 8, which was not observed in OR (-1.1±18.2%, p>0.05). In OR, plantarflexion twitch contraction time increased between weeks 5 and 10 82.2±34.4% (p<0.01), which was not observed in NOR. No changes were observed in the H-reflex and V-wave responses in either of the groups. In conclusion, short term overreaching can also reduce the performance of the neuromuscular system, however, it seems to be more muscle than neural based. To avoid overreaching, more individualized periodization should be used during basic training.To enhance neuromuscular performance, maximal and explosive strength training should also be added into the basic training program.

The last 4 weeks of basic military training are very stressful. We tested the hypothesis that changes in cardiac autonomic function during this period are associated with changes in maximal oxygen uptake and/or serum hormonal concentrations in male conscripts (n022). Cardiac vagal autonomic function was assessed by measuring the high-frequency (0.15Á0.4 Hz) spectral power of RÁR intervals. Maximal oxygen uptake (V ˙O2max ) and basal serum testosterone concentration were measured at the beginning and end of the period. Individual changes in vagally mediated high-frequency power (range (15% to '25%) correlated (r 00.73, P 00.001) with changes in V ˙O2max (range (9% to '6%) and changes in testosterone concentration (range (52% to '43%; r 00.43, P00.047). The mean values of V ˙O2max and testosterone concentration did not change during the study period. Measurements of autonomic function could be a useful tool for indicating adaptation to the highly stressful conditions associated with basic military training.