A. MANDROUKAST. METAXASN. KESIDISK. CHRISTOULAS...
p.113-120页
查看更多>>摘要：Aim. The aim of the present study was to examine the adaptation of myosin heavy chain (MHC) isoforms, capillary density and fiber cross sectional area (CSA) of deltoid muscle in adolescent and adult elite Greco-Roman wrestlers. Methods. Eighteen Greco-Roman wrestlers were divided into two groups: adolescents included 10 athletes (group A) between 14-18 years of age (15.4±1.3 yrs) and adults included 8 athletes (group B) between 20-27 years (23.5±2.6 yrs). Histochemical analyses were used to determine the muscle fiber type distribution and the muscle fiber cross sectional area. MHC isoform composition was determined with protein electrophoresis, while capillary density (capillary to fiber ratio and capillaries per mm~2) analysis was performed with a-amy-lase Periodic and Schiff staining. Results. Adolescents demonstrated a significantly higher percentage of type I fibers (P<0.05) and type I fiber area (P<0.05) compared to the adults. The percentage of type IIa fiber area were significantly higher in adult wrestlers (P<0.05). MHC I isoforms was significantly higher in adolescents (P<0.05), whereas the MHC isoforms of IIa and IIx did not differ between groups. The capillary density (mm~2) were significantly higher (P<0.05) in adolescents compared to adults. Conclusion. Our findings suggest that the observed muscle fiber profile in the deltoid muscle of wrestlers may represent an adaptation based on the mechanical and biochemical demands of the long-term training. Such adaptations are linked to the specific characteristics of the training program, the level and the previous training experience of the wrestlers.
查看更多>>摘要：Aim. The effects of sprint training regimes of varying distance schedules on the oxygen delivery-extraction relationship were investigated in 15 young (22±1 years) healthy males national-level sprinters. Method. During one session subjects performed four sprints, in a schedule of increasing distance order (100,200,300 and 400 m), and during the other session, in a schedule of decreasing distance order (400,300,200, and 100 m). All sprint bouts were performed on a treadmill at a speed of 22 km/rr1, which corresponds to 85% of subjects' maximal speeds. The order of the running sequences during sessions was balanced over subjects. Results. During both sprint schedules, all variables except for oxygen extraction in the incremented training regime, increased significantly from rest to exercise. Training regimes were not different with regard to cardiac output and absolute oxygen uptake. However, the decreasing compared to the increasing scheme was characterized by significantly (P<0.05) higher mean values of heart rate (194.5±4.1 185.2±5.7 beats/min~(-1), respectively), oxygen extraction (54.3±3.8 and 47.1+3.4 mL/L~(-1), respectively) and lactate (10.6±0.5 and 9.2±0.7 mmol/L1, respectively), while stroke volume was significantly (P<0.05) lower (100.4±4.5 and 109.7±4.4 mL, respectively). Conclusion. The present study indicates that in sprinters performing a similar distance at the same speed, but under different training regimes interplay exists between oxygen delivery and extraction, suggesting a link between the type of training scheme and physiological cardiovascular and skeletal muscle metabolic adaptations. This may explain the absence of differences between the conditions in absolute oxygen uptake and peak power output.
G. S. M. PINTOC. ABRANTESJ. P. BRITOJ. S. NOVAES...
p.126-131页
查看更多>>摘要：Aim. Little is known about the physiological response during slideboard exercise (SE). The aim of the present study was to analyse the oxygen uptake (VO_2), the heart rate (HR) and the energy expenditure (EE) during a typical slideboard exercise session and investigate differences on these variables when performing the same choreography at two different cadences (130 e 145 beats per minute - bpm). Methods. The sample comprised 13 female university students (21,77±0,97years), apparently healthy and physically active, with past training in SE and mastering the technical levels 1 and 2. The subjects performed randomly exercise sessions at 130bpm and 145 bpm. The ventilatory response was measured by an open air circuit system (COSMED K4b2, Rome, Italy) and HR was measured by a portable monitor (Polar Wireless Double Electrode, Kempele,Finland). HR and VO_2, during SE at 130 bpm, were 179.88±834 bpm and 37.95±3.71 mL/kg/min respectively. At 145 bpm SE mean values were 182.08±9.58 bpm and 39.67±3.82 mL/kg/min respectively. EE during 130bpm exercise was 10.60±1.69 kcal/min and at 145 bpm was 10.90+1.36 kcal/min. No differences were found between 130 and 145 bpm in none of the variables. We conclude that slideboard exercise cardio respiratory response does not seem affected by the rhythm of execution. Moreover the EE associated with this type of exercise is above the literature reports for other types of group aerobic exercises.
D. CONRADSSONC. FRIDENL. NILSSON-WIKMARB. O. AENG...
p.132-138页
查看更多>>摘要：Aim. Skating technique in cross-country skiing is a complex multi-joint movement with kinematics comparable to those of the standing squat exercise where any restricted joint mobility in the lower extremity-chain may change the movement pattern. The aim of this pilot study was to investigate the effect of ankle mobility on trunk posture during squat exercise in crosscountry skiers. Methods. Seven elite junior cross-country skiers (age range 17-19 years) performed two different standing squats, one with hands on hips and one with arms extended above the head. The squats were recorded on video and analyzed in selected positions: 90° and maximal knee flexion. Segment angles for shank and trunk were calculated from anatomical references relative to vertical/horizontal orientation in space. Recordings from passive ankle dorsiflexion were correlated with 1) trunk flexion, and 2) angle index (trunk flexion relative to shank angle). Results. Reduced ankle dorsiflexion was moderately associated with increased trunk flexion with hands on hips (r=-0.51 to -0.57), and arms above head (r=-0.61 to -0.64). Further, reduced dorsiflexion was also moderately associated with decreased angle index with hands on hip (r=0.60 to 0.67) but highly associated with decreased angle index with arms above head (r=0.75 to 0.76). Conclusion. The results imply that reduced ankle dorsal mobility is related to decreased angle index as well as increased trunk flexion during squat exercise, thus indicating the relevance of good ankle joint mobility for appropriate upper-body posture during squat exercise.
R. DI GIMINIANIR. MANNOR. SCRIMAGLIOG. SEMENTILLI...
p.139-151页
查看更多>>摘要：Aim. The first purpose of the present study was to assess acute, residual and chronic effects of whole-body vibration on hamstring and lower back flexibility through the application of an individual frequency of vibration. The second purpose was to determine whether the applied vibration intervention over time influences flexibility and reactive strength differently. Methods. Thirty-four young physically active subjects (19 female and 15 male) were randomly assigned to either a Control or a Vibration Group. Lower back and hamstring flexibility was measured using the Stand and Reach Test The reactive strength was estimated calculating the power in Drop Jump. Results. During whole-body vibration the relative change in acute flexibility for the Vibration Group (5.30±1.67 cm, 284%) reached a level of significance (P=0.038) compared to that of the Control Group (3.14±2.11 cm, 84%). Statistically significant differences in residual flexibility between the two groups were found at 6-min after the conclusion of vibration (P=0.034), at which point the Vibration Group showed the maximal relative change to pre-test (6.31±3.36 cm, 138%) versus the Control Group (3.06±1.87 cm, 20%). Chronic exposure of whole-body vibration did not produce significant changes in flexibility over time (P>0.05), whereas power in the Drop Jump performance of the Vibration Group increased significantly resulting in a benefit of 16% (P=0.019). Conclusion. The current study shows that individualized whole-body vibration without superimposing other exercises is an effective method of acutely increasing lower back and hamstring flexibility. Furthermore, the applied individualized whole-body vibration over tune influences the reactive strength rather than flexibility.
查看更多>>摘要：Aim. The purpose of this study was to assess maximal grip force in two conditions of voluntary muscular contraction (MVC) and electrical stimulation superimposed on voluntary muscular contraction (SES) to better understand mechanisms and effectiveness of electrical stimulation of the hand. There is conflicting evidence regarding the effectiveness of electrical stimulation superimposed on voluntary muscular contraction on improving maximal force. Increased knowledge of the physiologic and mechanical effects of electrical stimulation applied during voluntary muscular contraction can lead to refinement of its clinical application. Methods. Twenty subjects (36±13 years; 17 males and 3 females) participated in this study. All subjects were undergoing physical therapy within a hand rehabilitation center. They were instructed to randomly perform three grip determinations in both voluntary muscular contraction and superimposed electrical stimulation conditions to elicit maximal grip force of the unaffected hand. Force was assessed using a handheld dynamometer. Subjective force and contraction were assessed just after sessions as well as pain and discomfort using a visual analogue scale. Results. The mean force values were 22±7 kg and 30±l kg for the superimposed electrical stimulation and voluntary muscular contraction conditions, respectively. Analyses of the force measures showed that force was weaker in the superimposed electrical stimulation condition (P<0.001). Patients rated their pain and discomfort at 0±0 mm and 4±2.9 mm, respectively. Conclusion. Maximal grip force is reduced when electrical stimulation is superimposed to voluntary muscular contraction. This result could be explained by unbalanced muscular synergies at the hand due to SES, confirming these synergies as essential to produce maximal grip force.
查看更多>>摘要：Aim. The aim of this study was to evaluate the body composition and physiological effects in young sedentary overweight women after an indoor cycle training period. Methods. Fourteen subjects (22.6±2.1 yrs; 25-29.9 BMI) were trained for 12 weeks in a specific indoor cycling protocol (ICP) consisting of three sessions/week carried out in a fitness room. Body composition and physiological parameters were taken before the beginning of the study and after 12,24 and 36 sessions. Results. We observed a reduction of 2.6% and 3.2% in body weight and of 4.3 % and 5 % in fat mass after 24 and 36 sessions respectively (P<0.05). Lean mass increased by 2.3 % and 2.6 % respectively after 24 and 36 sessions. Body circumferences diminished in response to ICP. Resting heart rate decreased by 6.5% and 9% respectively after 24 and 36 sessions. After the tenth week, we found a reduction of 11 beats-min~(-1) in average training heart rate, an increase of 0.5 mL/kg~(-1)min~(-1)in average training oxygen uptake and an increase of 8.6 Watts in average power output. Moreover, an increase in cardio-respiratory fitness was observed (37.1±4.3 vs. 40.2±4.6 mL/kg~(-1)min~(-1)) after 36 sessions. Conclusion. The decrease in body weight, without any restriction on food consumption, and the improvement in cardio-respiratory fitness suggests that ICP may be efficient for losing weight and preventing the increased risk of cardiovascular disease in young overweight women. Indoor cycling can be performed by young sedentary overweight women; however, it is fundamental to formulate training protocols which are intensity and length specific to the fitness level of the participants.
E. SAEZ SAEZ DE VILLARREALB. REQUENAF. ARAMPATZIK. SALONIKIDIS...
p.166-173页
查看更多>>摘要：Aim. The main purpose of this study was to investigate the influence of 8-wk periodized plyometric training (PT) on chair-rise, jumping and sprinting performance in three groups of women of different age (40-50; 50-60; 60-70 years). Methods. This study involved a group of 55 women between the ages of 40 and 70 with no PT experience participating in a gymnastic program and recreational activity that did not involve jumping and who had participated since five years. All tests to determine the values of strength endurance, vertical jumping performance (VJP) and velocity were carried out before (PRE), after (POST) and following 8 weeks of rest (DETRAINING) of the 8 weeks of PT. The performance tests were completed in 3 days. Results. The primary finding of this investigation indicates that low impact PT using moderate volume of jumps produced similar enhancements in the three age groups of women in jumping and chair-rise performance (30 CST) (ranging 15-24 %). There were no enhancements in 10 m-sprint time in any of the age groups. In addition, 8 weeks of detraining following an 8 week PT program resulted in similar decreases in chair-rise and jumping performance in all training groups, whereas no further changes were observed in 10-m sprint time. Conclusion. The low impact PT proposed appears to be an optimal stimulus for improving VJP and 30 CST during short-term training periods in untrained middle-aged and elderly women.
M. J. COELHO E SILVAH. MOREIRA CARVALHOC. E. GONCALVESA. J. FIGUEIREDO...
p.174-181页
查看更多>>摘要：Aim. The influence of maturity status on body size, functional capacities and basketball-specific skills was evaluated and mul-tivariate relationships between domains of variables were examined in 80 male basketball players 12.0-13.9 years. Methods. Height, body mass and two skinfolds were measured. Stage of pubic hair (PH) was assessed clinically. Functional capacity was assessed with the vertical jump (squat jump, counter-movement jump), 2-kg medicine ball throw, hand grip strength, 60-second sit-ups and endurance shuttle run. Performances on four basketball skills were tested: shooting, passing, dribbling and defensive movements. Analysis of covariance with age as the covariate was used to test differences among players by stage of puberty. Associations among body size, adiposity, functional capacities and skills were evaluated with canonical correlation analysis. Results. Maturity status explained a significant portion of variance in body size (F=50.13, P<0.01,η~2=057, for height; F=13.47, P<0.01,η~2=0.26, for weight). The effect of pubertal status was significant for the jumps and upper limb strength, but not for sit-ups or aerobic endurance. Canonical correlations showed an inverse relationship of height and adiposity with skill tests, and a positive relationship between skills and a combination of abdominal muscular strength (sit-ups) and aerobic endurance. Conclusion. Skill appeared to be independent of pubertal status and the tallest group of basketball players did not attain better scores in basketball-specific skill tests.
查看更多>>摘要：Aim. The aim of this study was to investigate muscle damage and inflammatory response following eccentric exercise as well as the effect of carbohydrate supplement on these responses in untrained men. Methods. Eighteen healthy untrained men were randomly allocated into two carbohydrate (age 21/33±0/7 years) and placebo (age 20/66±l/22 years) groups. Forty-five repetitions of eccentric elbow flexion were performed with 90% of one maximum repetition by each subject. The exercises were done as three sets of 15 repetitions with 3 minutes rest between sets. Venous blood samples were obtained at pre-exercise, immediately, 8h, and 24h after exercise. Subjects consumed a 6% carbohydrate or placebo drink immediately following the exercise session, every hour, for 10 hours. Results. CK activities and IL-6 levels were significantly greater than per-exercise in immediately, 8 h and 24 h after exercise in both groups (P<0.05). No significant increases was observed in CRP levels immediately, 8 h and 24 h after exercise versus baseline, in both groups (P>0.05), but in 8 h versus immediately after exercise, the augmentation in the carbohydrate group was significant(P<0.05). Blood glucose increased significantly 8 h after exercise versus baseline in both groups (P<0.05). There was significant difference in serum IL-6 between two groups in 8 h and 24 h after exercise (P<0.05) and it was greater in carbohydrate group, There was no significant difference in serum CK, CRP, and glucose between two groups (P>0.05). Conclusion. According to results, carbohydrate increased the inflammatory (IL-6) response following resistance exercise, but had no effects on CRP and CK.
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