Combination of novel and traditional cardiorespiratory indices for the evaluation of adolescent volleyball players.

BACKGROUND: Although cardiopulmonary exercise (CPX) test is an essential tool for the assessment of functional capacity in athletes, limited information exists regarding the cardiorespiratory efficiency in young elite volleyball players. The main objective of the present study was to determine the maximal oxygen uptake (VO2max) and ventilatory anaerobic threshold (VT) during the CPX test in young male and female volleyball players. Moreover, to describe the behavior of the novel cardiorespiratory optimal point (COP) index and to assess its association with VO2max and VT. METHODS: Eleven adolescent male (15.18 ± 0.75 years old) and 13 female (14.77 ± 0.44 years old) volleyball players underwent a graded maximal exercise test on a treadmill until exhaustion in order to obtain VO2max, VT and COP. The COP was set as the lowest ventilation (VE)/VO2 ratio at a given minute of spiroergometry. RESULTS: COP values did not differ significantly between the two sexes (19.81 ± 1.29 and 20.44 ± 2.63 in males and females, respectively) and it was achieved at a speed of 3.41 ± 0.89 km/hr in males, and 3.78 ± 0.76 km/hr in females, lower than that achieved at the VT. COP was not correlated with VO2max (56.32 ± 6.36 ml/kg/min and 44.78 ± 3.65 ml/kg/min) nor with VT (34.81 ± 10.13 ml/kg/min and 34.13 ± 5.87 ml/kg/min) in male and female young volleyball players, respectively. CONCLUSIONS: The novel submaximal cardiorespiratory index of COP does not seem to be associated with the traditional aerobic capacity indices in athletes such as VO2max and VT. Thus, it probably constitutes a separate parameter that needs to be further evaluated regarding its significance both in clinical evaluation and sports performance assessment of athletes. HIPPOKRATIA 2019, 23(2): 70-74.

Indirect estimation of VO2max in athletes by ACSM's equation: valid or not?

AIM: The purpose of this study was to assess the indirect calculation of VO2max using ACSM's equation for Bruce protocol in athletes of different sports and to compare with the directly measured; secondly to develop regression models predicting VO2 max in athletes. METHODS: Fifty five male athletes of national and international level (mean age 28.3 ± 5.6 yrs) performed graded exercise test with direct measurement of VO2 through ergospirometric device. Moreover, 3 equations were used for the indirect calculation of VO2max: a) VO2max= (0.2 · Speed) + (0.9 · Speed · Grade) + 3.5 (ACSM running equation), b) regression analysis model using enter method and c) stepwise method based on the measured data of VO2. Age, BMI, speed, grade and exercise time were used as independent variables. RESULTS: Regression analysis using enter method yielded the equation (R=.64, standard error of estimation [SEE] = 6.11): VO2max (ml·kg(-1)·min(-1)) = 58.443 - (0.215 · age) - (0.632 · BMI) - (68.639 · grade) + (1.579 · time) while stepwise method (R = .61, SEE = 6.18) led to: VO2max (ml·kg(-1)·min(-1)) = 33.971 - (0.291 · age) + (1.481 · time). The calculated values of VO2max from these regression models did not differ significantly from the measured VO2max (p>.05). On the contrary, VO2max calculated from the ACSM's running equation was significantly higher from the actually measured value by 14.6% (p <.05). CONCLUSIONS: In conclusion, it seems that ACSM's equation is not capable of accurately predicting VO2max in athletes aged 18-37 years using Bruce protocol. Only the regression models were correlated moderately with the actually measured values of VO2max.

Heart rate variability modifications following exercise training in type 2 diabetic patients with definite cardiac autonomic neuropathy.

OBJECTIVES: Cardiac autonomic neuropathy (CAN) as a result of diabetic autonomic neuropathy is positively related to a poor prognosis in diabetic patients. The measurement of heart rate variability (HRV) is a remarkable index of cardiac autonomic dysfunction. The aim of this study was to examine the effects of long-term exercise training on HRV in type 2 diabetic patients with definite CAN. METHODS: Seventeen type 2 diabetic patients with definite CAN (group A: 56.2 years (SD 5.8)) and 15 without CAN (group B: 55.8 years (SD 5.6)) participated in the study. All patients followed an aerobic exercise training programme three times a week for 6 months; the intensity of the session was 70% to 85% of heart rate reserve. At the beginning and end of the study all subjects underwent graded maximal exercise testing with spiroergometry for the evaluation of their aerobic capacity (VO(2)peak). Moreover, time and frequency domain indices of HRV were obtained from 24 h ambulatory continuous ECG Holter recordings. RESULTS: At baseline, all measurements of HRV indices were significantly reduced in group A compared with group B (p<0.05). Moreover, group A reached a significantly lower VO(2)peak by 14.8% compared with group B (p<0.05). Following the exercise training programme, the SD of all normal-to-normal RR intervals in the entire recording (SDNN) was increased by 18.8% (p<0.05) and 13.8% (p<0.05), the square root of the average of sum of squares of difference between adjacent filtered RR intervals (rMSSd) was increased by 35% (p<0.05) and 15.2% (p<0.05), and the percentage of differences between adjacent filtered RR intervals which was greater than 50 ms for the entire analysis (pNN50) was increased by 400% (p<0.05) and 67.9% (p<0.05) in groups A and B, respectively. Regarding the frequency domain indices, only the high frequency power (HF) was found to be significantly increased in group A. At the end of the exercise training programme, SDNN, rMSSd and low frequency power (LF) were significantly lower (24.3% (p<0.05), 20.3% (p<0.05) and 40% (p<0.05), respectively) in group A compared with group B. Also, VO(2)peak increased by 17.8% (p<0.05) in group A and by 11% (p<0.05) in group B. Furthermore, the exercise training programme had significant effects on blood lipid and glucose levels and glycosylated haemoglobin (HbA(1c)) in both groups. CONCLUSIONS: The results indicate that 6-month aerobic exercise training improves the cardiac autonomic nervous system function in type 2 diabetic patients. However, more favourable effects are found in type 2 diabetic patients with definite CAN.

Seasonal variation of aerobic performance in soccer players according to positional role.

AIM: The purpose of this study was to evaluate the seasonal variation in the cardiorespiratory fitness of soccer players according to positional role in the team. METHODS: Thirty-two male soccer players U-19 years old were studied, consisting of 10 central defenders (18.2+/-0.9 years and 8.5+/-1.6 years of training (Group A), 12 midfielders (18+/-1 years and 8.1+/-1.4 years of training (Group B) and 10 attackers (18.2+/-0.9 years and 8.4+/-1.5 years of training (Group C). All subjects underwent anthropometric measurements and maximal exercise tests on a treadmill four times during their annual training cycle and maximal blood lactate accumulation analysis in order to verify that maximal exertion was reached. The measurements took place in the beginning and at the end of the preparation period, in the middle as well as at the end of the competitive season. RESULTS: Group A showed increased VO2(max) (mL.kg(-1.)min(-1)) by 19.3% in the 2nd measurement, by 22.9% in the 3rd and by 17.6% in the 4th compared to the beginning, respectively (P

Effects of athletic training on heart rate variability triangular index.

The purpose of this study was to assess the heart rate variability triangular index (HRVI) in elite track and field athletes. Sixty healthy males (mean aged 22.1 +/- 3.5 years) -15 long distance runners (group A), 15 speed runners (Group B), 15 throwers (Group C) and 15 non-trained subjects (Group D) were submitted to spiroergometric test, m-mode echocardiography and 24-h ambulatory ECG monitoring. The HRVI, mean heart rate, mean interval between two consecutive R waves of the QRS complexes (R-R interval) and standard deviation of the R-R (SDRR) were assessed through time domain method on computed 24-h Holter recordings. The HRVI and the SDRR were 62.2 +/- 9.6 and 220 +/- 40 ms correspondingly in group A, 52.7 +/- 6.0 and 210 +/- 40 ms in B, 44.5 +/- 5.3 and 180 +/- 40 ms in C, 39.3 +/- 6.4 and 180 +/- 30 ms in D. The HRVI and the mean R-R were found to differ statistically between groups A, B and C versus D (P < 0.05). However, the higher value in HRVI was found in group A. Maximal oxygen consumption (VO2max) was 62.0 +/- 4.4 ml kg-1 min-1 in group A, 52.7 +/- 6.0 in group B, 44.6 +/- 5.3 in C and 41.6 +/- 6.0 in D. The higher value in VO2max was also found in group A. The left ventricular mass index (LVMI) and end-diastolic volume index (EDVI) were 136 g m-2 and 83 ml m-2 correspondingly in group A, 136 and 79 in B, 124 and 56 in C and 88 and 55 in group D. The HRVI was found to have a significant relationship with VO2max and EDVI only in group A. On the other hand, no significant relationships were found between HRVI and LVMI in all groups. It is concluded, that the enhanced HRVI in athletes is affected by exercise training pattern. Moreover, HRVI depends on the level of VO2max in endurance-trained, but is independent from the extent of myocardial hypertrophy in all types of training.