IJCS | Volume 31, Nº3, May/ June 2018

215 Regarding vital signs, there was a decrease in mean SBP, DBP and HR at rest. This fact is due to the decrease in the activation of the sympathetic nervous system and the increase of the parasympathetic system at rest in the individuals submitted to the training. 14,15 As for the anthropometric data, amean increase in bodyweight was observed, with an increase in LM and marked reduction in FM. At the beginning of the training program, the military had FM values ​considered above the desirable for their age and gender, 16 and these values decreased to levels considered appropriate after the military training program. The decrease in FM is related to the increase in intensity and/or duration of training, 17 also demonstrated in this study. The cardiac adaptations were compatible with eccentric cardiac remodeling. There was a significant increase in LV dimensions and mass, and tendency to increase the LA volume. It is known that cardiac remodeling resulting from physical exercise is related to the increase and harmonious hypertrophy of the cardiac cavities, also influencing the right cavities. 17,18 During the special operations course, the percentage of military personnel with eccentric hypertrophy (RWT < 0.42 and LVMI > 115g/m 2 ) 19 practically doubled (from 5.9% to 11.8%). The verified changes result from the training intensity, frequency and method. Although the special operations training program consists of dynamic and static exercises, the dynamic training predominates. Frequency and intensity are other factors that contribute to high cardiac output, with corresponding volume overload and cardiac chamber dilatation. 20 At the functional level, there was a decrease in LVEF, which agreeswithwhat has been previously described. 21-23 This occurs because athletes submitted to intense and prolonged exertion may show a slight decrease in resting LVEF. Several factorsmay contribute to this phenomenon, such as the athletes’ ability to significantly increase LVEF during exercise at the expense of increased LV diastolic dimensions, which, through the Frank-Starling mechanism, is associated with increased preload, more effective diastolic filling and lower LV systolic volume, allowing a considerable increase in ejection volume. 22 Another possible explanation is that LVEF represents an estimate of LV function and not directly of myocardial contractility, whichmay underestimate its capacity when submitted to intense exertion. Also, the mathematical formula used to calculate LVEF (100 x ejection volume/ LVDD) in hearts with increased cavities underestimates LV performance. 22 In this study, despite the verified adaptations, one can say the latter were within ranges considerednormal (none of themilitary hadLVEF< 50%at the initial or final evaluations). However, after themilitary training program, 12 individuals (approximately 70% of the population) had LVEF at rest between 50 and 55%. Myocardial GLS was studied using the speckle- tracking technique, and it was verified that the military had values within the ranges considered normal. There was a decrease in the absolute value of GLS, but it did not reach a statistically significant difference, probably due to the small sample size. This parameter may be important to differentiate left ventricular hypertrophy associatedwith exercise anddisease, namely hypertrophic cardiomyopathy, since values ​of myocardial mechanics, withinnormal values, suggest physiological alterations. 24-26 The literature on cardiac remodeling resulting from physical exercise in athletes is vast, 27-30 but the existing bibliography in the military population is smaller. The authors did not find in the literature a study that addressed cardiovascular variations in competitive athletes when submitted to an intense military training program. Particularly in Portugal, in the Army special operations group, this is the first study that associated the military physical exercise trainingwith the cardiovascular remodeling resulting from it. Limitations The present study has some limitations. The first is the small sample assessed. The great physical and mental demands of this type of training mean that the number of individuals who successfully finish it is a small one. The second is the absence of a control group, and the fact that the individuals who dropped out of the course were not re-evaluated, to compare their results with the ones that finished the military training. The third limitation is the fact that the individuals were not further evaluated with aerobic physical fitness indicators, cardiopulmonary exercise test, and muscle strength tests, before and at the end of the course, to evaluate the real impact of training on the heart and gains in physical and functional capacity. The cardiopulmonary exercise testing would be important to more accurately determine the training range based on maximal HR. Fourth, the quantification of unprogrammed training practiced by the individuals during the special operations course, very common in this context, limits the more objective determination of this variable, which is probably underestimated. During the course, these individuals are permanently involved Dinis et al. Cardiac Remodeling Induced by MilitaryTraining International Journal of Cardiovascular Sciences. 2018;31(3)209-217 Original Article