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Aquatic Sports and Activities

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Journal Details
Format
Journal
eISSN
1899-7562
ISSN
1640-5544
First Published
13 Jan 2009
Publication timeframe
5 times per year
Languages
English

Search

Volume 19 (2008): Issue 2008 (June 2008)

Journal Details
Format
Journal
eISSN
1899-7562
ISSN
1640-5544
First Published
13 Jan 2009
Publication timeframe
5 times per year
Languages
English

Search

13 Articles
Open Access

Evolution of Motor Control: From Reflexes and Motor Programs to the Equilibrium-Point Hypothesis

Published Online: 24 Oct 2008
Page range: 3 - 24

Abstract

Evolution of Motor Control: From Reflexes and Motor Programs to the Equilibrium-Point Hypothesis

This brief review analyzes the evolution of motor control theories along two lines that emphasize active (motor programs) and reactive (reflexes) features of voluntary movements. It suggests that the only contemporary hypothesis that integrates both approaches in a fruitful way is the equilibrium-point hypothesis. Physical, physiological, and behavioral foundations of the EP-hypothesis are considered as well as relations between the EP-hypothesis and the recent developments of the notion of motor synergies. The paper ends with a brief review of the criticisms of the EP-hypothesis and challenges that the hypothesis faces at this time.

Keywords

  • motor control
  • reflexes
  • equilibrium-point hypothesis
Open Access

Timing of the Vibration of Arm Muscles Affects Grip Force Control

Published Online: 24 Oct 2008
Page range: 25 - 38

Abstract

Timing of the Vibration of Arm Muscles Affects Grip Force Control

The purpose of the study was to investigate how the timing of application of vibration to the arm muscles affects grip force. Eight healthy subjects performed similar tasks of lifting and holding an object without any vibration (NV) and with vibration applied to the extrinsic wrist and finger muscles at different times during the task: 1) applied immediately prior to the task performance (AFV) and 2) during the task performance (DFV). Peak grip force, static grip force, and acceleration of the object were recorded. Vibration applied to the muscles during the task performance did not affect grip force generation. However, when vibration was applied prior to the task performance, a significant increase in grip force was observed. We suggest that the differences in magnitudes of grip force between the conditions are associated with the availability of information from muscle spindles and/or joint and tactile afferents. It appears that vibration applied during the task performance affects only muscles spindles, while a five-minute vibration applied prior to the lift of the object affects both muscle spindles and joint and tactile afferents. The results of the study provide additional information on the availability of afferent information in the control of grip force.

Keywords

  • muscle vibration
  • hand
  • grip force control
Open Access

Evaluation of the Limits of Stability (LOS) Balance Test

Published Online: 24 Oct 2008
Page range: 39 - 52

Abstract

Evaluation of the Limits of Stability (LOS) Balance Test

The main objective of this study was the estimation of intrasession reliability of the limits of stability (LOS) test conducted on a force platform as an alternative measurement to standard posturography in quiet standing. Fifteen healthy adults took part in the experiment. The standardized measurement protocol of the LOS test was proposed. It consists of three phases - 1st phase - 10s of quiet standing, 2nd phase - the maximal forward leaning in a self paced manner, and 3rd phase - maintenance of maximal forward leaning position. The analysis of variance Friedman's ANOVA and Repeated Measures ANOVA/MANOVA was used to diagnose the differences between 10 consecutive trials of the LOS test. In order to establish reliability of the test, the intraclass correlation (ICC) procedure was used. We presented different ways of maximal center of pressure (COP) excursion estimates. The results of this study show no significant differences between the chosen parameters of the LOS test. Moreover, the measurement of the range of COP excursion, which is most commonly analyzed in such tests, showed to be quite reliable with ICC2,1 above .85. LOS test conducted along the standard procedure should be considered as a very useful method in clinical and research conditions. Still the specific parameters of the LOS test should be given more thorough insight, but it is a very good alternative to quiet standing posturography.

Keywords

  • posture
  • limits of stability
  • dynamic balance
  • functional stability
Open Access

Differences in Peripheral Perception between Athletes and Nonathletes

Published Online: 24 Oct 2008
Page range: 53 - 62

Abstract

Differences in Peripheral Perception between Athletes and Nonathletes

In team games, due to the great number of stimuli, perceptive skills have a cardinal significance, especially in players' anticipation and decisionmaking processes. The aim of this study was to compare peripheral perception of handball players (n=16) and nonathletes (n=16) of the same age. A comparative analysis involves abilities connected with general visual functions - such as the field of vision (hardware system) and reaction time to visual stimuli (software system). Peripheral perception was examined using the peripheral perception test included in the Vienna Test System (Schuhfried, Austria). The results show that the examined groups did not differ in regards to visual functions connected with the peripheral field of vision and the correctness of stimuli recognition. Handball players had a significantly shorter response time to stimuli appearing in the peripheral field of vision compared to nonathletes.

Keywords

  • peripheral perception
  • team games
  • athletes
Open Access

Information Processes, Stimulation and Perceptual Training in Fencing

Published Online: 24 Oct 2008
Page range: 63 - 82

Abstract

Information Processes, Stimulation and Perceptual Training in Fencing

Learning and development of motor skills and techniques in fencing and other sports with open motor habits are based on perceptual processes involving the senses of vision, touch, and hearing. In fencing, the same stimuli can yield defensive or offensive actions, which are strictly related to the tactics and strategy. Different types of stimulation determine reaction time, movement time, and muscle bioelectric tension (EMG) in fencing. From the training process, controlling the significance of dominant stimuli should be taken into account. The results of presented studies of advanced and novice fencers show that the time of reaction to tactile stimulation is similar or slightly shorter than to acoustic stimuli followed by visual stimuli. The advanced fencers were faster than the novice fencers in all the studied parameters. The EMG signal was significantly lower in case of advanced fencers in all three types of stimulation. It can be a proof that the psycho-motor superiority of elite fencers results in a reduction of the bioelectrical tension of muscles involved in performing the motor tasks. Perceptual skills enable athletes to respond to important signals in sport competition and ignore disrupting ones which lower the effectiveness of sports combat. Time pressure during sports competition makes it necessary to reduce as much as possible the decision-making time and the time of sensorimotor responses in the motor phase. The study results show that experienced athletes make decisions much faster than their novice colleagues. It conforms to the main strategy of perceptual training, (i.e., gaining maximum benefits at the lowest expense). Speed of decision-making is strictly associated with the stimuli detection effectiveness and re-creation of acquired motor patterns.

Keywords

  • choice reaction
  • movement speed
  • tactile stimulus
  • perception
  • fencing
Open Access

Blood-Brain Barrier and Exercise – a Short Review

Published Online: 24 Oct 2008
Page range: 83 - 92

Abstract

Blood-Brain Barrier and Exercise – a Short Review

Blood-brain barier (BBB) segregates central nervous system (CNS) from the circulating blood. BBB is formed by the brain capillary endothelial cells with complex tight junctions between them as well as by astrocytes and pericytes. BBB is responsible for transport of selected chemicals into and out of the CNS as well as for its protection from fluctuations in plasma composition following meals, during exercise and from circulating agents such as neurotransmitters, xenobiotics and other potentially harmful substances capable to disturb neural function. BBB may be compromised during CNS injury, infection, fever and in some nerodegenerative diseases. The increase of BBB permeability was observed also during exercise as documented by changes of plasma S-100 protein levels, used as a peripheral marker of BBB integrity. Marked change in BBB integrity during exercise may disturb normal brain function and contribute to the development of central fatigue. Moreover, serum S-100β may indicate level of injury in individuals suffering brain injuries during sports. There are also data suggesting that acute effect of physical exercise on serum S100β levels may not be related with CNS injury. Further studies to establish whether training and which type of it may modulate BBB permeability are needed.

Keywords

  • blood-brain barrier
  • astrocytes
  • S100 β protein
Open Access

Evaluation of the Blood Antioxidant Capacity in Two Selected Phases of the Training Cycle in Professional Soccer Players

Published Online: 24 Oct 2008
Page range: 93 - 108

Abstract

Evaluation of the Blood Antioxidant Capacity in Two Selected Phases of the Training Cycle in Professional Soccer Players

The aim of this study was to evaluate the effects of a regular pre-season training on the aerobic performance and the blood antioxidant defense capacity in soccer players from the Polish Premier League club (n=19) and IVth League team (n=15). The players participated in an incremental treadmill running exercise to volitional fatigue twice (i.e., at the beginning (Trial A) and the end (Trial B) of the pre-season spring training). In venous blood samples, taken at rest and 3 min post-test, the activities of antioxidant enzymes (SOD, GSH-Px, CAT, GR) and concentrations of non-enzymatic antioxidants (GSH, tocopherols, retinol, uric acid) and malondialdehyde as a lipid peroxidation biomarker were measured. With the aim of between-group comparisons and possible conclusions on training-induced changes in the capacity of the blood antioxidant defense, the POTAX index was calculated as a sum of standardized activities of antioxidant enzymes and concentrations of non-enzymatic antioxidants.

The results of the present study indicate that the players from the Premier League club were characterized by only slightly higher maximal oxygen uptake rates, the differences compared to IVth League team, as assessed in both trials, were statistically insignificant. Participation in the pre-season training resulted in a moderate improvement of aerobic performance, although only a few players were characterized by VO2max comparable to the international-class elite performers. No distinct differences were observed in the level of aerobic performance between higher- and lower-classified players.

Pre-season training led to an improvement in the global blood antioxidant capacity expressed in terms of POTAOX indices, although the changes in the activities and concentrations of individual components of the antioxidant system were less pronounced. Training-induced level of antioxidant conditioning was higher among the Premier League players, which may be related to differences in the training schedule and nutritional preparation of the athletes.

Keywords

  • antioxidant defense
  • blood
  • soccer
Open Access

Determination and Prediction of One Repetition Maximum (1RM): Safety Considerations

Published Online: 24 Oct 2008
Page range: 109 - 120

Abstract

Determination and Prediction of One Repetition Maximum (1RM): Safety Considerations

Strength training is recommended for slowing age-dependent deterioration of muscular strength and for rehabilitating patients with muscle weakening illnesses. Reliable assessment of muscle strength is important for proper design of strength training regimes for prevention, rehabilitation, and sport. One repetition maximum (1RM) is an established measure of muscular strength and is defined as the value of resistance against which a given movement can be performed only once. Proper assessment of 1RM is time consuming, and may lead to muscle soreness as well as temporary deterioration of the function of the tested muscles. Attempts at indirect 1RM determination based on the maximum number of repetitions performed have predicted 1RM with a variable degree of accuracy. Cardiovascular safety has been neglected in 1RM determination, although arterial blood pressure increases considerably when exercising against maximal or near maximal resistance. From the perspective of cardiovascular safety, favorable 1RM measurement methods should avoid performance of repetitions until failure; movement against high resistance and muscle fatigue both increase blood pressure. Although such techniques are likely less accurate than the current methods, their prediction accuracy be sufficient for therapeutic strength training.

Keywords

  • strength exercise
  • hemodynamic response
  • blood pressure
Open Access

Serum Osteocalcin Concentration in Treadmill-Trained Adult Male Wistar Rats

Published Online: 24 Oct 2008
Page range: 121 - 130

Abstract

Serum Osteocalcin Concentration in Treadmill-Trained Adult Male Wistar Rats

Mechanical stress is considered to be essential for the regulation of bone mass. The purpose of this study was to determine whether treadmill exercise at moderate intensity induces alterations in blood osteocalcin concentration in rats. Male Wistar rats, aged 5 months, were divided randomly into two groups: trained animals (n = 6) and controls (n = 7). Trained rats were exercised 5 days/week for 4 weeks on a motor-driven treadmill. Each exercise session lasted 60 minutes and the average locomotion speed was 16.2 m/min. After completion of the training period, a blood sample was taken for osteocalcin measurement and the hindlimbs medial gastrocnemius muscles were excised and weighed. Comparative analysis showed significantly lower circulating osteocalcin levels in the exercised rats in comparison to control animals. It is possible that the observed decreased blood osteocalcin concentration is transient in nature. Factors including stress may also influenced the results.

Serum osteocalcin concentration in treadmill-trained rats

Keywords

  • osteocalcin
  • rat
  • treadmill training
Open Access

Changes in Aerobic and Anaerobic Power Indices in Elite Handball Players Following a 4-Week General Fitness Mesocycle

Published Online: 24 Oct 2008
Page range: 131 - 140

Abstract

Changes in Aerobic and Anaerobic Power Indices in Elite Handball Players Following a 4-Week General Fitness Mesocycle

The aim of this study was to evaluate the effects of a 4-week training programme during the first phase of the preparation period on selected indices of somatic structure as well as aerobic and anaerobic power in elite handball players. Nine handball players from a first league team took part in the study; their average age was 25.5±3.7 years, body mass 86.5±7.6 kg (I session) and 87.9±7.3 kg (II session) (p<0.01), lean body mass - 74.4±6.6 kg (I) and 76.2± 6.2 kg (II) (p<0.01), body fat mass 12.1±3.1 kg (I) and 11.7±3.1 kg (II) respectively. Two evaluations were conducted - the first at the end of the season, the second at the initial phase of the preparation period. The second phase was preceded by a 4- week period of general endurance and strength training. Aerobic fitness was assessed indirectly, taking into account the results of the PWC170 test. The absolute and relative values of the PWC170 index increased significantly from 236.6 W to 269 W (p<0.01) and from 2.73 W/kg to 3.06 W/kg (p<0.01). The values of maximum oxygen uptake - VO2max were significantly improved from 3.65 l/min to 3.98 l/min (p<0.01) and from 42.3 ml/kg/min to 45.4 ml/kg/min (p<0.05). Anaerobic fitness was assessed using the 30-second Wingate test. A statistically significant improvement of the basic indices of aerobic fitness following the 4-week training programme proved its high effectiveness. Maintaining the level of the basic indices of anaerobic power despite the absence of specific training loads, seems to corroborate the strong effect of genetic factors on the level of anaerobic fitness and the effectiveness of strength training programs.

Keywords

  • aerobic fitness
  • anaerobic fitness
  • handball
Open Access

Groin Pain in Athletes – Clinical Experience

Published Online: 24 Oct 2008
Page range: 141 - 148

Abstract

Groin Pain in Athletes – Clinical Experience

Dysfunction of lumbo-pelvic area is a common problem in many sports. Due to insufficient data supporting variables predisposing to lumbo-pelvic dysfunction, and a lack of standards in thorough assessment, understanding the overall problem continues to provide clinical complications; and unfortunately, the prognosis is less than promising. Most often this type of non-contact injury in the groin area is seen in dynamic sports involving running, sprinting, and sports performed over longer time periods, where fatigue plays an important role (soccer, rugby, hockey). There have been proposals in identifying most probable factors influencing the occurrence of pelvic overload injury. Among those we can list: muscle strength and balance, training regimen (including warm-up), fatigue, flexibility, body mechanics, sports specific activities, movement technique, previous injury, and psychological state. During clinical assessment by the physician and physiotherapist, many of these risks of injury factors are found. Currently more attention is given to neuromuscular factors that can affect risk of this pathology.

Our clinical experience suggests that poor neuromuscular control and lack of strength may significantly contribute to injury in the lumbo-pelvic and groin area. Certain objective indexes (e.g., hamstrings to quadriceps strength H/Q, stability deficits) can be important indicators of injury risk, as well as guidelines for motor dysfunction recovery.

Keywords

  • sports injuries
  • motor control
  • neuromuscular training
  • exercise-related transient abdominal pain (ETAP)
Open Access

The Influence of Sodium Phosphate Supplementation on VO2max, Serum 2,3-diphosphoglycerate Level and Heart Rate in Off-road Cyclists

Published Online: 24 Oct 2008
Page range: 149 - 164

Abstract

The Influence of Sodium Phosphate Supplementation on VO<sub>2max</sub>, Serum 2,3-diphosphoglycerate Level and Heart Rate in Off-road Cyclists

The main objective of the work was to evaluate the influence of a six day supplementation with sodium phosphate on circulatory and pulmonary variables, the level of 2,3-diphosphoglycerate (2,3-DPG) and the concentration of inorganic phosphates in blood serum of elite off-road cyclists. The research material included 19 cyclists which were randomly divided into a experimental group, supplemented with sodium phosphate and a control group receiving a placebo The subjects in the experimental group ingested sodium diphosphate in a dose of 50mg/kg of fat free mass per day. The supplement was ingested in even doses, four times per day. The control group received 4g of glucose in gelatin capsules (500mg), which were also divided into 4 even portions. During the experiment a significant (p<0.05) increase in maximal oxygen uptake was observed (VO2max), maximal minute ventilation (VEmax), as well as oxygen pulse (O2/HR). Also a significant decrease in resting and maximal exercise heart rate occurred. This was also true for each exercise load. A significant (p<0.05) increase in the serum concentration of non-organic phosphates (P) was observed which was accompanied by a decrease in serum calcium (Ca) concentration. The changes in the resting and post exercise concentration of 2,3-DPG were non significant, yet the supplementation procedure showed a tendency for increased level of this variable.

Keywords

  • sodium phosphate supplementation
  • 2, 3-DPG
  • VO
  • heart rate
  • off-road cyclists
Open Access

Warm-up: A case study on maximal oxygen consumption as it relates to acute stretching

Published Online: 24 Oct 2008
Page range: 165 - 176

Abstract

Warm-up: A case study on maximal oxygen consumption as it relates to acute stretching

The aim of this study was to determine the acute effects of static and Proprioceptive Neuromuscular Facilitation (PNF) stretches on maximal oxygen consumption (VO2 max). Ten physically active men (mean ± SD, 23.80 ± 1.54 years, 70.60 ± 9.70 kg, 1.74.60 ± 5.23 m), who were healthy students volunteered to take part in the study. The participants were subjected to Static and PNF stretching exercises. After the interventions, the Bruce treadmill protocol was applied to measure VO2 max values. The expired gases were collected and analyzed continuously using the Cortex Metalyzer II. Analysis of variance showed significant main effects for interventions (F(2,18)=10.74, p<.05) on VO2 max. The main result of this study showed that both static and PNF stretching exercises improved VO2 max values.

Keywords

  • stretching
  • PNF
  • maximal oxygen uptake
13 Articles
Open Access

Evolution of Motor Control: From Reflexes and Motor Programs to the Equilibrium-Point Hypothesis

Published Online: 24 Oct 2008
Page range: 3 - 24

Abstract

Evolution of Motor Control: From Reflexes and Motor Programs to the Equilibrium-Point Hypothesis

This brief review analyzes the evolution of motor control theories along two lines that emphasize active (motor programs) and reactive (reflexes) features of voluntary movements. It suggests that the only contemporary hypothesis that integrates both approaches in a fruitful way is the equilibrium-point hypothesis. Physical, physiological, and behavioral foundations of the EP-hypothesis are considered as well as relations between the EP-hypothesis and the recent developments of the notion of motor synergies. The paper ends with a brief review of the criticisms of the EP-hypothesis and challenges that the hypothesis faces at this time.

Keywords

  • motor control
  • reflexes
  • equilibrium-point hypothesis
Open Access

Timing of the Vibration of Arm Muscles Affects Grip Force Control

Published Online: 24 Oct 2008
Page range: 25 - 38

Abstract

Timing of the Vibration of Arm Muscles Affects Grip Force Control

The purpose of the study was to investigate how the timing of application of vibration to the arm muscles affects grip force. Eight healthy subjects performed similar tasks of lifting and holding an object without any vibration (NV) and with vibration applied to the extrinsic wrist and finger muscles at different times during the task: 1) applied immediately prior to the task performance (AFV) and 2) during the task performance (DFV). Peak grip force, static grip force, and acceleration of the object were recorded. Vibration applied to the muscles during the task performance did not affect grip force generation. However, when vibration was applied prior to the task performance, a significant increase in grip force was observed. We suggest that the differences in magnitudes of grip force between the conditions are associated with the availability of information from muscle spindles and/or joint and tactile afferents. It appears that vibration applied during the task performance affects only muscles spindles, while a five-minute vibration applied prior to the lift of the object affects both muscle spindles and joint and tactile afferents. The results of the study provide additional information on the availability of afferent information in the control of grip force.

Keywords

  • muscle vibration
  • hand
  • grip force control
Open Access

Evaluation of the Limits of Stability (LOS) Balance Test

Published Online: 24 Oct 2008
Page range: 39 - 52

Abstract

Evaluation of the Limits of Stability (LOS) Balance Test

The main objective of this study was the estimation of intrasession reliability of the limits of stability (LOS) test conducted on a force platform as an alternative measurement to standard posturography in quiet standing. Fifteen healthy adults took part in the experiment. The standardized measurement protocol of the LOS test was proposed. It consists of three phases - 1st phase - 10s of quiet standing, 2nd phase - the maximal forward leaning in a self paced manner, and 3rd phase - maintenance of maximal forward leaning position. The analysis of variance Friedman's ANOVA and Repeated Measures ANOVA/MANOVA was used to diagnose the differences between 10 consecutive trials of the LOS test. In order to establish reliability of the test, the intraclass correlation (ICC) procedure was used. We presented different ways of maximal center of pressure (COP) excursion estimates. The results of this study show no significant differences between the chosen parameters of the LOS test. Moreover, the measurement of the range of COP excursion, which is most commonly analyzed in such tests, showed to be quite reliable with ICC2,1 above .85. LOS test conducted along the standard procedure should be considered as a very useful method in clinical and research conditions. Still the specific parameters of the LOS test should be given more thorough insight, but it is a very good alternative to quiet standing posturography.

Keywords

  • posture
  • limits of stability
  • dynamic balance
  • functional stability
Open Access

Differences in Peripheral Perception between Athletes and Nonathletes

Published Online: 24 Oct 2008
Page range: 53 - 62

Abstract

Differences in Peripheral Perception between Athletes and Nonathletes

In team games, due to the great number of stimuli, perceptive skills have a cardinal significance, especially in players' anticipation and decisionmaking processes. The aim of this study was to compare peripheral perception of handball players (n=16) and nonathletes (n=16) of the same age. A comparative analysis involves abilities connected with general visual functions - such as the field of vision (hardware system) and reaction time to visual stimuli (software system). Peripheral perception was examined using the peripheral perception test included in the Vienna Test System (Schuhfried, Austria). The results show that the examined groups did not differ in regards to visual functions connected with the peripheral field of vision and the correctness of stimuli recognition. Handball players had a significantly shorter response time to stimuli appearing in the peripheral field of vision compared to nonathletes.

Keywords

  • peripheral perception
  • team games
  • athletes
Open Access

Information Processes, Stimulation and Perceptual Training in Fencing

Published Online: 24 Oct 2008
Page range: 63 - 82

Abstract

Information Processes, Stimulation and Perceptual Training in Fencing

Learning and development of motor skills and techniques in fencing and other sports with open motor habits are based on perceptual processes involving the senses of vision, touch, and hearing. In fencing, the same stimuli can yield defensive or offensive actions, which are strictly related to the tactics and strategy. Different types of stimulation determine reaction time, movement time, and muscle bioelectric tension (EMG) in fencing. From the training process, controlling the significance of dominant stimuli should be taken into account. The results of presented studies of advanced and novice fencers show that the time of reaction to tactile stimulation is similar or slightly shorter than to acoustic stimuli followed by visual stimuli. The advanced fencers were faster than the novice fencers in all the studied parameters. The EMG signal was significantly lower in case of advanced fencers in all three types of stimulation. It can be a proof that the psycho-motor superiority of elite fencers results in a reduction of the bioelectrical tension of muscles involved in performing the motor tasks. Perceptual skills enable athletes to respond to important signals in sport competition and ignore disrupting ones which lower the effectiveness of sports combat. Time pressure during sports competition makes it necessary to reduce as much as possible the decision-making time and the time of sensorimotor responses in the motor phase. The study results show that experienced athletes make decisions much faster than their novice colleagues. It conforms to the main strategy of perceptual training, (i.e., gaining maximum benefits at the lowest expense). Speed of decision-making is strictly associated with the stimuli detection effectiveness and re-creation of acquired motor patterns.

Keywords

  • choice reaction
  • movement speed
  • tactile stimulus
  • perception
  • fencing
Open Access

Blood-Brain Barrier and Exercise – a Short Review

Published Online: 24 Oct 2008
Page range: 83 - 92

Abstract

Blood-Brain Barrier and Exercise – a Short Review

Blood-brain barier (BBB) segregates central nervous system (CNS) from the circulating blood. BBB is formed by the brain capillary endothelial cells with complex tight junctions between them as well as by astrocytes and pericytes. BBB is responsible for transport of selected chemicals into and out of the CNS as well as for its protection from fluctuations in plasma composition following meals, during exercise and from circulating agents such as neurotransmitters, xenobiotics and other potentially harmful substances capable to disturb neural function. BBB may be compromised during CNS injury, infection, fever and in some nerodegenerative diseases. The increase of BBB permeability was observed also during exercise as documented by changes of plasma S-100 protein levels, used as a peripheral marker of BBB integrity. Marked change in BBB integrity during exercise may disturb normal brain function and contribute to the development of central fatigue. Moreover, serum S-100β may indicate level of injury in individuals suffering brain injuries during sports. There are also data suggesting that acute effect of physical exercise on serum S100β levels may not be related with CNS injury. Further studies to establish whether training and which type of it may modulate BBB permeability are needed.

Keywords

  • blood-brain barrier
  • astrocytes
  • S100 β protein
Open Access

Evaluation of the Blood Antioxidant Capacity in Two Selected Phases of the Training Cycle in Professional Soccer Players

Published Online: 24 Oct 2008
Page range: 93 - 108

Abstract

Evaluation of the Blood Antioxidant Capacity in Two Selected Phases of the Training Cycle in Professional Soccer Players

The aim of this study was to evaluate the effects of a regular pre-season training on the aerobic performance and the blood antioxidant defense capacity in soccer players from the Polish Premier League club (n=19) and IVth League team (n=15). The players participated in an incremental treadmill running exercise to volitional fatigue twice (i.e., at the beginning (Trial A) and the end (Trial B) of the pre-season spring training). In venous blood samples, taken at rest and 3 min post-test, the activities of antioxidant enzymes (SOD, GSH-Px, CAT, GR) and concentrations of non-enzymatic antioxidants (GSH, tocopherols, retinol, uric acid) and malondialdehyde as a lipid peroxidation biomarker were measured. With the aim of between-group comparisons and possible conclusions on training-induced changes in the capacity of the blood antioxidant defense, the POTAX index was calculated as a sum of standardized activities of antioxidant enzymes and concentrations of non-enzymatic antioxidants.

The results of the present study indicate that the players from the Premier League club were characterized by only slightly higher maximal oxygen uptake rates, the differences compared to IVth League team, as assessed in both trials, were statistically insignificant. Participation in the pre-season training resulted in a moderate improvement of aerobic performance, although only a few players were characterized by VO2max comparable to the international-class elite performers. No distinct differences were observed in the level of aerobic performance between higher- and lower-classified players.

Pre-season training led to an improvement in the global blood antioxidant capacity expressed in terms of POTAOX indices, although the changes in the activities and concentrations of individual components of the antioxidant system were less pronounced. Training-induced level of antioxidant conditioning was higher among the Premier League players, which may be related to differences in the training schedule and nutritional preparation of the athletes.

Keywords

  • antioxidant defense
  • blood
  • soccer
Open Access

Determination and Prediction of One Repetition Maximum (1RM): Safety Considerations

Published Online: 24 Oct 2008
Page range: 109 - 120

Abstract

Determination and Prediction of One Repetition Maximum (1RM): Safety Considerations

Strength training is recommended for slowing age-dependent deterioration of muscular strength and for rehabilitating patients with muscle weakening illnesses. Reliable assessment of muscle strength is important for proper design of strength training regimes for prevention, rehabilitation, and sport. One repetition maximum (1RM) is an established measure of muscular strength and is defined as the value of resistance against which a given movement can be performed only once. Proper assessment of 1RM is time consuming, and may lead to muscle soreness as well as temporary deterioration of the function of the tested muscles. Attempts at indirect 1RM determination based on the maximum number of repetitions performed have predicted 1RM with a variable degree of accuracy. Cardiovascular safety has been neglected in 1RM determination, although arterial blood pressure increases considerably when exercising against maximal or near maximal resistance. From the perspective of cardiovascular safety, favorable 1RM measurement methods should avoid performance of repetitions until failure; movement against high resistance and muscle fatigue both increase blood pressure. Although such techniques are likely less accurate than the current methods, their prediction accuracy be sufficient for therapeutic strength training.

Keywords

  • strength exercise
  • hemodynamic response
  • blood pressure
Open Access

Serum Osteocalcin Concentration in Treadmill-Trained Adult Male Wistar Rats

Published Online: 24 Oct 2008
Page range: 121 - 130

Abstract

Serum Osteocalcin Concentration in Treadmill-Trained Adult Male Wistar Rats

Mechanical stress is considered to be essential for the regulation of bone mass. The purpose of this study was to determine whether treadmill exercise at moderate intensity induces alterations in blood osteocalcin concentration in rats. Male Wistar rats, aged 5 months, were divided randomly into two groups: trained animals (n = 6) and controls (n = 7). Trained rats were exercised 5 days/week for 4 weeks on a motor-driven treadmill. Each exercise session lasted 60 minutes and the average locomotion speed was 16.2 m/min. After completion of the training period, a blood sample was taken for osteocalcin measurement and the hindlimbs medial gastrocnemius muscles were excised and weighed. Comparative analysis showed significantly lower circulating osteocalcin levels in the exercised rats in comparison to control animals. It is possible that the observed decreased blood osteocalcin concentration is transient in nature. Factors including stress may also influenced the results.

Serum osteocalcin concentration in treadmill-trained rats

Keywords

  • osteocalcin
  • rat
  • treadmill training
Open Access

Changes in Aerobic and Anaerobic Power Indices in Elite Handball Players Following a 4-Week General Fitness Mesocycle

Published Online: 24 Oct 2008
Page range: 131 - 140

Abstract

Changes in Aerobic and Anaerobic Power Indices in Elite Handball Players Following a 4-Week General Fitness Mesocycle

The aim of this study was to evaluate the effects of a 4-week training programme during the first phase of the preparation period on selected indices of somatic structure as well as aerobic and anaerobic power in elite handball players. Nine handball players from a first league team took part in the study; their average age was 25.5±3.7 years, body mass 86.5±7.6 kg (I session) and 87.9±7.3 kg (II session) (p<0.01), lean body mass - 74.4±6.6 kg (I) and 76.2± 6.2 kg (II) (p<0.01), body fat mass 12.1±3.1 kg (I) and 11.7±3.1 kg (II) respectively. Two evaluations were conducted - the first at the end of the season, the second at the initial phase of the preparation period. The second phase was preceded by a 4- week period of general endurance and strength training. Aerobic fitness was assessed indirectly, taking into account the results of the PWC170 test. The absolute and relative values of the PWC170 index increased significantly from 236.6 W to 269 W (p<0.01) and from 2.73 W/kg to 3.06 W/kg (p<0.01). The values of maximum oxygen uptake - VO2max were significantly improved from 3.65 l/min to 3.98 l/min (p<0.01) and from 42.3 ml/kg/min to 45.4 ml/kg/min (p<0.05). Anaerobic fitness was assessed using the 30-second Wingate test. A statistically significant improvement of the basic indices of aerobic fitness following the 4-week training programme proved its high effectiveness. Maintaining the level of the basic indices of anaerobic power despite the absence of specific training loads, seems to corroborate the strong effect of genetic factors on the level of anaerobic fitness and the effectiveness of strength training programs.

Keywords

  • aerobic fitness
  • anaerobic fitness
  • handball
Open Access

Groin Pain in Athletes – Clinical Experience

Published Online: 24 Oct 2008
Page range: 141 - 148

Abstract

Groin Pain in Athletes – Clinical Experience

Dysfunction of lumbo-pelvic area is a common problem in many sports. Due to insufficient data supporting variables predisposing to lumbo-pelvic dysfunction, and a lack of standards in thorough assessment, understanding the overall problem continues to provide clinical complications; and unfortunately, the prognosis is less than promising. Most often this type of non-contact injury in the groin area is seen in dynamic sports involving running, sprinting, and sports performed over longer time periods, where fatigue plays an important role (soccer, rugby, hockey). There have been proposals in identifying most probable factors influencing the occurrence of pelvic overload injury. Among those we can list: muscle strength and balance, training regimen (including warm-up), fatigue, flexibility, body mechanics, sports specific activities, movement technique, previous injury, and psychological state. During clinical assessment by the physician and physiotherapist, many of these risks of injury factors are found. Currently more attention is given to neuromuscular factors that can affect risk of this pathology.

Our clinical experience suggests that poor neuromuscular control and lack of strength may significantly contribute to injury in the lumbo-pelvic and groin area. Certain objective indexes (e.g., hamstrings to quadriceps strength H/Q, stability deficits) can be important indicators of injury risk, as well as guidelines for motor dysfunction recovery.

Keywords

  • sports injuries
  • motor control
  • neuromuscular training
  • exercise-related transient abdominal pain (ETAP)
Open Access

The Influence of Sodium Phosphate Supplementation on VO2max, Serum 2,3-diphosphoglycerate Level and Heart Rate in Off-road Cyclists

Published Online: 24 Oct 2008
Page range: 149 - 164

Abstract

The Influence of Sodium Phosphate Supplementation on VO<sub>2max</sub>, Serum 2,3-diphosphoglycerate Level and Heart Rate in Off-road Cyclists

The main objective of the work was to evaluate the influence of a six day supplementation with sodium phosphate on circulatory and pulmonary variables, the level of 2,3-diphosphoglycerate (2,3-DPG) and the concentration of inorganic phosphates in blood serum of elite off-road cyclists. The research material included 19 cyclists which were randomly divided into a experimental group, supplemented with sodium phosphate and a control group receiving a placebo The subjects in the experimental group ingested sodium diphosphate in a dose of 50mg/kg of fat free mass per day. The supplement was ingested in even doses, four times per day. The control group received 4g of glucose in gelatin capsules (500mg), which were also divided into 4 even portions. During the experiment a significant (p<0.05) increase in maximal oxygen uptake was observed (VO2max), maximal minute ventilation (VEmax), as well as oxygen pulse (O2/HR). Also a significant decrease in resting and maximal exercise heart rate occurred. This was also true for each exercise load. A significant (p<0.05) increase in the serum concentration of non-organic phosphates (P) was observed which was accompanied by a decrease in serum calcium (Ca) concentration. The changes in the resting and post exercise concentration of 2,3-DPG were non significant, yet the supplementation procedure showed a tendency for increased level of this variable.

Keywords

  • sodium phosphate supplementation
  • 2, 3-DPG
  • VO
  • heart rate
  • off-road cyclists
Open Access

Warm-up: A case study on maximal oxygen consumption as it relates to acute stretching

Published Online: 24 Oct 2008
Page range: 165 - 176

Abstract

Warm-up: A case study on maximal oxygen consumption as it relates to acute stretching

The aim of this study was to determine the acute effects of static and Proprioceptive Neuromuscular Facilitation (PNF) stretches on maximal oxygen consumption (VO2 max). Ten physically active men (mean ± SD, 23.80 ± 1.54 years, 70.60 ± 9.70 kg, 1.74.60 ± 5.23 m), who were healthy students volunteered to take part in the study. The participants were subjected to Static and PNF stretching exercises. After the interventions, the Bruce treadmill protocol was applied to measure VO2 max values. The expired gases were collected and analyzed continuously using the Cortex Metalyzer II. Analysis of variance showed significant main effects for interventions (F(2,18)=10.74, p<.05) on VO2 max. The main result of this study showed that both static and PNF stretching exercises improved VO2 max values.

Keywords

  • stretching
  • PNF
  • maximal oxygen uptake

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