Panagiotis Stefanidis

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.

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.

Energy cost during running and cycling in climbers and mountain bike riders

IntroductionRunning economy (RE) is defined as the energy cost (EC) for a given velocity of submaximal running and it is determined by measuring the steady condition consumption of oxygen (VO2) and the respiratory exchange ratio (RER) (Saunders et al., 2004). Runners who have a better EC, use less energy and less oxygen ,at the same speed, than runners with poor running economy. There is a strong association between EC and distance running performance, with EC being a better predictor of performance than maximal oxygen uptake (VO2max) in elite runners, who have a similar VO2max (Saunders et al., 2004). A number of physiological and biomechanical factors seem to influence RE and EC, including temperature, heart rate, ventilation, VO2max, age, gender, body mass, muscle fiber type distribution and other biomechanical variables (Morgan et al., 1989; Daniels & Daniels, 1992; Morgan & Craib, 1992; Pate et al., 1989; Saunders et al., 2004). Lower running economy is a result of neuromuscular fitting shortage and the disability of elastic energy utilization. Contrarily, higher running economy is due to better neuromuscular coordination and coordinated movement and it leads to a greater performance. Metabolic adaptations in muscles, with increased density of muscle mitochondria, oxidative enzymes and better ability to store and utilize elastic energy by the muscles lead to a lower EC of running (Saunders et al., 2004).None of the athletes seems to consume 22% more oxygen than high level runners at the same steady condition speed (Costiel, 1986). Comparing high level runners with moderately trained runners, the results show better EC for the first group (Morgan et al., 1992). Long distance runners also present better economy, than semi-distance and sprint runners. It leads to a greater EC, at a 150 to 300 Kcal, in a marathon race for elite runners, compared to moderately trained runners (Conley et al., 1980; Daniels et al., 1992). EC is also correlated with muscle tissue apportion. Cyclists with better energy cost have a greater amount of type I fibers in leg muscles. It is calculated that performance factor of fibers type I is 27 %, and type II is 13% (Coyle et al., 1992, 1999).It has been suggested that a higher percentage of slow-twitch muscle fibres is associated with better running economy. (Bosco et al., 1987; Williams et al., 1987). The relationship between EC and performance is well established for running (Cavanagh & Kram, 1989), walking (Minetti et al., 1995) and cycling (Hagberg et al., 1981). A Treadmill running and cycle ergometry comparison showed similar parameters of the VO2 responses, except for the VO2 slow component, which was significantly greater for cycling than for running (Carter et al., 2000). Oxygen uptake seems to be lower and blood lactate higher for a brief period of intense nonsteady state cycling as compared to uphill running .On the contrary, anaerobic energy cost is higher for cycling, although in terms of work efficiency those two can be similar (Scott et al., 2006). Also metabolic cost of submaximal cycling in different pedalling rates rises in a linear regression with speed and pedal rate (McDaniel et al., 2002). The majority of studies indicate that runners achieve a higher VO2max on treadmill, whereas cyclists can achieve a VO2max value in cycle ergometry similar to that in treadmill running (Millet et al., 2009). An increase of energy cost along with exercise duration had already been observed for prolonged exercises such as running (Davies et al., 1986) and cycling (Lepers et al., 2000). All mountain bike riders (MTB) seem to have similar physical characteristics with climbers (Impellizseri & Marcora, 2007).Although in bibliography there are reports about studies, that examined energy cost and economy of cycling and running, there is no report concerning the comparison in the energy cost of climbers and MTB riders. The aim of the present study was to evaluate and compare the cardiorespiratory performance and energy cost in trained climbers and MTB athletes. …