Thomas I. Metaxas

Comparative study of field and laboratory tests for the evaluation of aerobic capacity in soccer players.

The purpose of this study was to evaluate the maximal oxygen uptake (VO2max) values in soccer players as assessed by field and laboratory tests. Thirty-five elite young soccer players were studied (mean age 18.1 ± 1.0 years, training duration 8.3 ± 1.5 years) in the middle of the playing season. All subjects performed 2 maximal field tests: the Yo-Yo endurance test (T1) for the estimation of VO2max according to normogram values, and the Yo-Yo intermittent endurance test (T2) using portable telemetric ergospirometry; as well as 2 maximal exercise tests on the treadmill with continuous (T3) and intermittent (T4) protocols. The estimated VO2max values of the T1 test (56.33 ml·kg-1·min-1) were 10.5%, 11.4%, and 13.3% (p ≤ 0.05) lower than those of the T2 (62.96 ml·kg-1·min-1), T3(63.59 ml·kg-1·min-1) and T4 (64.98 ml·kg-1·min-1) tests, respectively. Significant differences were also found between the intermittent exercise protocols T1 and T3 (p ≤ 0.001) and the continuous exercise protocols T2 and T4 (p ≤ 0.001). There was a high degree of cross correlation between the VO2max values of the 3 ergospirometric tests (T2 versus T3, r = 0.47, p ≤ 0.005; T2versus T4, r = 0.59, p ≤ 0.001; T3 versus T4 r = 0.79, p ≤ 0.001). It is necessary to use ergospirometry to accurately estimate aerobic capacity in soccer players. Nevertheless, the Yo-Yo field tests should be used by coaches because they are easy and helpful tools in the training program setting and for player follow-up during the playing season.

Preseason Physiological Profile of Soccer and Basketball Players in Different Divisions

Metaxas, TI, Koutlianos, N, Sendelides, T, and Mandroukas, A. Preseason physiological profile of soccer and basketball players in different divisions. J Strength Cond Res 23(6): 1704-1713, 2009-The purpose of this study was to examine and compare the cardiorespiratory performance and isokinetic muscle strength between Greek soccer and basketball players of different divisions before starting the training season. Study participants included 100 soccer players and 61 basketball players, who were assigned according to the kind of sport and division. All participants underwent anthropometric measurements and performed an exercise test on a treadmill to determine maximal oxygen uptake (&OV0312;o2max). Peak torque for quadriceps and hamstring muscles was measured on isokinetic dynamometer at angular velocity of 60 degrees/s−1, 180 degrees/s−1, and 300 degrees/s−1. The statistical p value was set at p < 0.05. In soccer players &OV0312;o2max in absolute and relative values was significantly lower in division IV compared to the other 3 divisions (3,413.4 ± 351.0 vs. 3,932.7 ± 551.2, 4,172.7 ± 371.8, 4,223.0 ± 323.8 ml·min−1, respectively; p < 0.001 and 46.93 ± 4.20 vs. 52.47 ± 3.66, 54.86 ± 3.80, 55.32 ± 3.33 ml·kg·min−1, respectively; p < 0.001). Basketball players presented significantly higher &OV0312;o2max, in absolute values, compared to soccer players for divisions II (4,586.3 ± 586.3 vs. 4,172.7 ± 371.8 ml·min−1; p < 0.05), III (4,319.6 ± 418.6 vs. 3,932.7 ± 551.2 ml·min−1; p < 0.01), and IV (4,624.0 ± 627.6 vs. 3,413.4 ± 351.0 ml·min−1; p < 0.001), respectively. Regarding peak torque, only basketball players showed significantly higher values at 60 degrees/sec−1 in hamstrings for III (p < 0.05) and IV division (p < 0.05). Conclusively, the higher &OV0312;o2max reached by professional soccer and basketball players compared to semiprofessional and amateur ones and between the soccer and basketball players of the same division can be attributed to the different duration of the maintenance period and to the effect of the training session on each sport, respectively. Finally, a higher level of muscle strength would be preferable in soccer and basketball and would reduce the risk for injuries in the maintenance and rebuilding training periods.

Effects of basketball training on maximal oxygen uptake, muscle strength, and joint mobility in young basketball players.

The purpose of this study was to examine the effects of prolonged basketball skills training on maximal aerobic power, isokinetic strength, joint mobility, and body fat percentage, in young basketball players, and controls of the same age. Twenty basketball players and 18 control boys participated in the study. Basketball players participated both in their schools physical education program and in a childrens basketball team training program. Controls participated only in their schools physical education program. All subjects were tested every 6 months (18 months total, 111/2, 12, 121/2, 13 years old) for &OV0312;O2max, peak torque values of the quadriceps and ham- strings at 180 and 300°·s-1 and range of motion of the knee and hip joints. Body fat percentage was assessed at the beginning and the end of the experimental period. Results showed that the basketball group had lower heart rate values in all ages and higher &OV0312;O2 values in the initial test compared with the control in submaximal intensity. The &OV0312;O2max was altered in both groups on the final test, when compared to the initial test. However, the basketball group had a higher &OV0312;O2max on each of the 6-month follow-up measurements, compared to the control group (p > 0.001). At the end of the 18-month follow-up period no significant differences were observed in isokinetic strength and joint mobility of the lower limbs between the 2 groups. On the contrary, the boys of the trained group had significantly lower percentage body fat values, compared to controls. In conclusion, regular basketball training increased aerobic power and decreased body fat percentage of prepubescent boys, while it did not affect muscle strength and joint mobility of the lower limbs. The major implication suggested by the findings of the present study is that, in order to improve the basic physical components, specific training procedures should be incorporated during the basketball training sessions. It is recommended that all children should be involved in some type of cardiovascular and resistance training program.

Non-invasive cardiac electrophysiological indices in soccer players with mitral valve prolapse

Background Cardiac disorders constitute the most common causes of sudden cardiac death (SCD) and mitral valve prolapse (MVP) is one of the cardiac structural causes in young populations. The aim of this study was to evaluate some reliable non-invasive electrophysiological variables of SCD in young athletes with mild or moderate MVP and to compare them with their cardiorespiratory adaptations. Design The study population comprised of 40 amateur male soccer players, who were equally subdivided into those with (group A, aged 20.4 ± 4.5 years) and without (group B, 18.4 ±2.4 years) MVP and 20 healthy age-matched sedentary individuals (group C). Methods All subjects underwent echo study for left ventricular mass index (LVMI) estimation, treadmill spiro-ergometric test for maximal oxygen uptake (VO2max) measurement and continuous ambulatory 24-h ECG recordings for arrhythmias detection and heart rate variability (HRV) analysis. Furthermore, groups A and B were also submitted to signal-averaged electrocardiogram for late potentials (LP) assessment and to submaximal exercise test for T-wave alternans (TWA) detection. Results Maximal oxygen uptake, LVMI and HRV index were enhanced in all athletes compared to group C (P < 0.05). Resting QTc interval was significantly prolonged only in group B (by 3.7%) compared to C (P < 0.05), whereas no significant difference was found between A and B. No positive LP or TWA were observed in all subjects. Significant correlation was found only between HRV index and VO2max in all groups. Conclusions Athletes with mild or moderate MVP do not present any significant difference in non-invasive cardiac electrophysiological indices as well as in cardiorespiratory performance, compared to healthy ones. It seems that long-term exercise induced adaptations overlap any cardiac autonomic disorders in cases of mild-to-moderate MVP severity.

The effect of different exercise-testing protocols on atrial natriuretic peptide.

The aim of this study was to examine and to compare alterations in the secretion of atrial natriuretic peptide (ANP) during different exercise‐testing protocols in moderately trained men. Fifteen healthy male physical education students were studied (mean age 22·3 ± 2·5 years, training experience 12·3 ± 2·5 years, height 1·80 ± 0·06 m, weight 77·4 ± 8·2 kg). Participants performed an initial graded maximal exercise testing on a treadmill for the determination of VO2max (duration 7·45–9·3 min and VO2max 55·05 ± 3·13 ml kg−1 min−1) and were examined with active recovery (AR), passive recovery (PR) and continuous running (CR) in random order. Blood samples for plasma ANP concentration were taken at rest (baseline measurement), immediately after the end of exercise as well as after 30 min in passive recovery time (PRT). The plasma ANP concentration was determined by radioimmunoassay (RIA). The results showed that ANP plasma values increased significantly from the rest period to maximal values. In the short‐term graded maximal exercise testing the ANP plasma values increased by 56·2% (44·8 ± 10·4 pg ml−1 versus 102·3 ± 31·3 pg ml−1, P<0.001) and in the CR testing the ANP levels increased by 29·2% (44·8 ± 10·4 pg ml−1 versus 63·3 ± 19·8 pg ml−1, P<0.001) compared to the baseline measurement. Moreover, the values of ANP decreased significantly (range 46·4–51·2%, P<0.001) in PRT after the end of the four different exercise modes. However, no significant difference was evident when ANP values at rest and after AR and PR were compared. It is concluded that the exercise testing protocol may affect the plasma ANP concentrations. Particularly, short‐term maximal exercise significantly increases ANP values, while the intermittent exercise form of active and passive recovery decreases ANP concentrations.

Morphology of the deltoid muscles in elite tennis players

Abstract The aim of this study was to examine the deltoid muscle properties of the dominant and non-dominant arm of Greek professional male tennis players. Eight male tennis players (mean age 22.0 years, s = 3.2) were subjected to biopsy of the deltoid muscle of both arms. Adenosine triphosphate (ATPase) histochemistry and myosin heavy chain (MHC) composition were performed on the samples with homogenate electrophoresis. No significant differences were observed in the percentage of types I, IIa, IIab, and IIb muscle fibres between the deltoid muscles of the two arms. Types I, IIa, and IIx muscle fibres of the dominant and non-dominant deltoid muscles did not differ significantly for MHC isoform composition. Type IIab muscle fibres showed a similar cross-sectional area (CSA) percentage distribution between the two arms. The CSA percentage for types I, IIa, and IIb muscle fibers did not differ significantly between the dominant and the non-dominant arm. We conclude therefore that regular tennis training probably does not lead to any significant changes in the muscle fibre types of the dominant and non-dominant arms of elite tennis players.

Cardiorespiratory and metabolic alterations during exercise and passive recovery after three modes of exercise.

Mandroukas, A, Heller, J, Metaxas, TI, Sendelides, T, Riganas, C, Vamvakoudis, E, Christoulas, K, Stefanidis, P, Karagiannis, V, Kyparos, A, and Mandroukas, K. Cardiorespiratory and metabolic alterations during exercise and passive recovery after three modes of exercise. J Strength Cond Res 25(6): 1664-1672, 2011—The objective of this study was to investigate the potential variations in cardiorespiratory and metabolic parameters and running performance among 3 modes of exercise of the same duration, namely, intermittent running with active recovery (AR) or passive recovery (PR) and continuous running (CR) and whether these variations could affect passive recovery time (PRT). Fifteen male physical education students with a subspecialty in soccer were studied (mean age 22.3 ± 2.5 years, training experience 12.3 ± 2.5 years) in the middle of the playing season. The results showed that during exercise, the highest heart rate (HR) and &OV0312;O2 values were observed in CR, whereas the lowest values in PR followed by AR. Blood lactate (BLa) concentration was higher in PR by 38% compared to that in AR (p < 0.05). The exercise duration was similar between PR and AR tests and longer than in CR. With regard to PRT, the highest HR (186 ± 9 b·min−1), &OV0312;O2 (55.5 ± 5.2 ml·kg−1·min−1), and BLa (5.1 ± 1.7 mmol·L−1) values were found in CR. No differences in HR and &OV0312;O2 between PR and AR were detected. However, despite the differences in BLa concentration between AR and PR during exercise, the PRT BLa values between these 2 exercise modes were not different. Among the 3 running protocols, only CR appeared to have fully challenged the cardiorespiratory system inducing maximal HR and &OV0312;O2 responses during exercise and high BLa values in PRT, yet these responses were not associated with better exercise performance compared to intermittent running. Therefore, intermittent exercise, regardless of implementing passive or active interval, might be the preferable exercise mode particularly in activities extended over 30 minutes.

Deltoid muscle characteristics in wrestlers.

The purpose of the present study was to investigate the deltoid muscle characteristics of wrestlers. Nine Greco-Roman competitive male wrestlers (mean age 20.1+/-2.7 yrs, height 175+/-0.6 cm, weight 83.2+/-12.5 kg, years of training 7.6+/-2.7 yrs) participated in this study. Six male healthy sedentary students (mean age 21.2+/-0.9 yrs, height 180+/-0.3 cm, weight 80.1+/-9.4 kg) served as controls. Muscle fibre distribution, cross-sectional area (CSA), as well as satellite cells, myonuclei and capillary density per muscle fibre area were determined by immunohistochemistry. Myosin heavy chain MHC isoform composition of single fibres was determined with protein electrophoresis. Immunohistochemical analysis showed that muscle fibre distribution of the MHC I and IIA were significantly higher in wrestlers than in controls (p<0.05). Electrophoretic analysis of single fibres revealed a significantly higher proportion of fibres containing MHC I and IIC in wrestlers (p<0.05). The mean CSA of type IIA fibres and the number of myonuclei per type II was significantly higher in wrestlers (p<0.05). We also found that the number of satellite cells was 2.5 fold higher in wrestlers than in the control group. This study suggests that the observed muscle fibre profile in the deltoid of wrestlers may represent an adaptation based on the specific mechanical and biochemical demands of the long-term training in Greco-Roman wrestling.

Impact of traditional Greek dancing on jumping ability, muscular strength and lower limb endurance in cardiac rehabilitation programmes

Aims: The objective of this study was to evaluate the effect of a training programme based on traditional Greek dance on the jumping ability, muscle strength and lower limb endurance in patients with chronic heart failure (CHF). Patients and methods: Forty Greek patients with CHF graded as NYHA ⩽ II and aged 73.2±4.7 years were randomly divided into two groups. Group A (n=20) participated in a three-month physical rehabilitation programme based on Greek traditional dances, whereas group B (n=20) remained untrained and served as the control group. All patients were studied before and after the 12-week exercise training programme. At baseline and follow-up the exercise capacity of the patients was evaluated by the six-minute walking test, their lower extremity muscle strength was evaluated by an isokinetic dynamometer and their jumping ability by the Myotest-Pro test, which includes three types of jumps (plyometric, countermovement and squat jumps). Results: No significant difference was observed between the two groups at the baseline evaluation. At follow-up, group A showed significant improvements in walking distance calculated from the six-minute walking test (10.0% improvement; p<0.05), in lower limb strength (10.32% improvement; p<0.05), and in countermovement jump speed (6.9%; p<0.05) and squat jump speed (5.8%; p<0.05). Group A also increased their jump plyometry height by 13.86% (p<0.05), their counter jump height by 10.68% (p<0.05) and their squat jump height by 10.45% (p<0.05). Group A had a 6.85% (p<0.05) increased force of counter jump compared with group B. Conclusion: The design and implementation of cardiac rehabilitation programmes using Greek traditional dances in patients with CHF are both safe and effective in improving lower limb function.