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w.gawronski@medicinasportiva.pl
e-ISSN 1734-2260 from 2005
ISSN 1429-0022 from 1997 till 2004
Indexed in: SportDiscus; EMBASE/Excerpta Medica; Index Copernicus
Medicina Sportiva 2009 vol. 13, Issue 1
Copyright ® 2008 Medicina Sportiva
Rehabilitation and recovery training after snowboard accidents
Thomas Kuepper, Nicola Huber, Nikolaus Netzer, Volker Schoeffl
Read article »
Circuit based deep water running improves cardiovascular fitness, strength and abdominal obesity in older, overweight women. Aquatic exercise intervention in older adults
Kimberley Meredith-Jones, Michael Legge, Lynnette M. Jones
Read article »
The influence of physical activity on body composition and the level of student’s flexibility
Tomasz Boraczyński, Lola Brygida Boraczyńska, Jerzy Urniaż
Read article »
An analysis of relations between a selfassessment of health and active life-style
Andrzej Knapik, Edward Saulicz, Michał Kuszewski, Ryszard Plinta
Read article »
Metabolic syndrome, physical activity and adipocytokines in children and adolescents
Toivo Jürimäe, Jaak Jürimäe, Jarek Mäestu
Read article »
Zinc contribution to the regulation of glucose disposal, lipid metabolism and striated muscle contractions
Grażyna Lutosławska, Agnieszka Fornal-Urban
Read article »
Gender differences after downhill running for voluntary isometric contractions of knee extensor muscles using surface EMG
Mark ET. Willems, Simon R. Northcott
Read article »
ASSESSMENT OF MAXIMAL LACTATE STEADY STATE IN ELITE FEMALE KAYAKERS
Vasileios Diafas, Konstantinos Chrysikopoulos, Vasiliki Diamanti, Sokratis Kaloupsis
Read article »
Rehabilitation and recovery training after snowboard accidents
Thomas Kuepper, Nicola Huber, Nikolaus Netzer, Volker Schoeffl
Objective: We aim to optimize specific recovery training with special regard to the style of snowboarding performed by the victims.
Background: With increasing popularity of snowboarding, accidents and injuries happen more often, but until now there is little data on sports specific recovery. Consequently physiotherapy is often performed with “standard” procedures which don’t take into account specific demands of snowboarding in general or the special demands of the different disciplines of snowboarding.
Material and Methods: Prospective observation of the course and result of rehabilitation performed according to the scheme described (open trial, n = 16). The paper also reviews the literature about the topic with special regard to the German literature, which is less easy accessible for the international reader.
Conclusions & Clinical advantages: All victims except one with spinal trauma recovered completely and went snowboarding the following season (some of them also for competitions). Recovery training of patients suffering from snowboard accidents should be started as soon as possible and sports specific demands should be taken into account. Optimal teamwork between the physician, the physiotherapist, the patient and the coach is necessary to optimize the results.
Key words: snowboard accidents, training, rehabilitation, winter sports
Read article »
Circuit based deep water running improves cardiovascular fitness, strength and abdominal obesity in older, overweight women. Aquatic exercise intervention in older adults
Kimberley Meredith-Jones, Michael Legge, Lynnette M. Jones
Introduction: Sedentary habits are associated with an increased risk of numerous chronic diseases; however, the type of exercise that may be most beneficial to improve health is still unclear. Water based exercise is rapidly growing in popularity as individuals, such as the elderly or the obese, can exercise at relatively high levels of intensity while imposing minimal strain on joints. However, little research has been conducted substantiating the health benefits of exercise in this medium.
Aim of the study: The purpose of this study was to evaluate the effects of a circuit based deep water running exercise program on aerobic capacity (VO2peak), strength and abdominal obesity in older, overweight/obese women
Materials and Methods: The participants (mean ± SD age 59 ± 9 years, BMI 33 ± 5 kg/m2, n=18) took part in a circuit based deep water running program with continuous deep water running (70-75% HRpeak) interspersed with 90 seconds of resistance exercises for 12 weeks, 60 min.day-1and 3 days.week-1.
Results: There were significant increases (p<.05) in VO2peak, (1.37 ± 0.10 vs 1.51 ± 0.08 L·min-1), and muscle strength (upper body 20 ± 7.1%, knee flexion 33 ± 7.9%, knee extension 32 ± 17.9%). There were significant reductions (p<.05) in waist circumference (105 ± 2.5 vs 100 ± 2.6 cm) and waist-hip ratio (0.90 ± 0.01 vs 0.87 ± 0.01).
Conclusions: These results indicate circuit based deep water running can elicit significant improvements in cardiorespiratory fitness, strength and abdominal obesity.
Keywords: cardiovascular disease, aquatic exercise, obesity
Read article »
The influence of physical activity on body composition and the level of student’s flexibility
Tomasz Boraczyński, Lola Brygida Boraczyńska, Jerzy Urniaż
Introduction. The purpose of the study was to assess the impact of physical activity on the body ingredients and the level of flexibility among students with various levels of physical activity.
Material and methods. The study involved 235 physical education students and 142 physiotherapy students (171 females and 206 males). The results provided information regarding their levels of physical activity. Their body ingredients were determined with the use of a Tanita BC 418 MA analyser. Their level of flexibility was assessed using the Modified Sit-and-Reach Test.
Results. The results of the study demonstrated a significantly lower body mass, lower fat content, lower value of the BMI index as well as a significantly higher level of flexibility (p<0.001) among students of physical education, compared to the students of physiotherapy.
Conclusions. The results indicate a positive impact of increased physical activity on the correct body mass as well as a very good level of flexibility.
Key words: body composition, flexibility, students
Read article »
An analysis of relations between a selfassessment of health and active life-style
Andrzej Knapik, Edward Saulicz, Michał Kuszewski, Ryszard Plinta
Introduction: Hypokinesis – a deficit in mobile activity, is thought to be one of the main causes of the appearance and development of the so called ‘diseases of civilization’. Optimising the level of activity against the needs is a complex issue. It requires taking into account different kinds of activity, their determinants, and correlations with various lifestyles as well as the impact on health. A diagnosis of the relation between the various kinds of activity and health can constitute the starting point for implementing application methods.
Objective: The objective was to define the impact of the different kinds of activity on the various factors and components of the self-assessment of health.
Materials and methods: 154 men aged 30-60 were tested with the application of sociometric methods. The following questionnaires were applied: self-assessment of activity levels (SEWL) and self-assessment of health (SF-36). A statistical analysis of the results of the research included the computation of Spearman’s indicators of correlation between the level of the various kinds of activity and the factors and components of health. Participants of the research were divided into quartiles according to the level of their self-assessment of health. Statistical description was done and the ANOVA analysis was made of variants between the top and bottom groups with the aim to finding the differences pertaining to the various kinds of activity. In each case p≤0.05 was assumed as the level of the significance of differences.
Results: Significant correlations between the physical and mental components of health and the sports factor were observed. In case of health factors, the correlations were observed with regards to physical mobility, activity and health in general also in relation to sports factor. Statistically relevant were the relations between physical mobility and activity (SEWL indicator) and also activity (spare time indicator). The ANOVA analysis of variants showed the statistical importance of the differences between the top and bottom quartiles of health self-assessment with regards to sports indicator and SEWL indicator.
Conclusions: The results of the research lead to the conclusion that physical activity plays a significant role in shaping the self-assessment of health, both its physical and mental components. The deciding factor seems to be the activity of a sporting nature which most strongly influences factors of health such as physical mobility, activity and general well-being.
Key words: hypokinesis, mobile activity, self-assessment of health
Read article »
Metabolic syndrome, physical activity and adipocytokines in children and adolescents
Toivo Jürimäe, Jaak Jürimäe, Jarek Mäestu
Metabolic syndrome is a major risk factor for cardiovascular diseases and type 2 diabetes. Biomarkers of the metabolic syndrome develop early in life and can be predictive of atherosclerotic processes in adulthood. Low physical activity levels in children, with a possible modulating effect of cardiorespiratory fitness have been associated with a higher clustering of metabolic risk factors in adults. All these markers are highly influenced by physical activity level and physical fitness. Evidence suggests that there is a significant genetic component involved in physical fitness phenotypes. However, there are very limited data in the literature on genetic predisposition to physical activity level in children and adolescents. Adipose tissue has now been considered as an endocrine organ that produces many molecules called adipocytokines. Leptin and adiponectin are most studied regarding the metabolic risk factors, while adiponectin is considered as one of the most promising biochemical marker to characterize metabolic syndrome in adults. There are yet no studies that have longitudinally investigated the complex changes of the metabolic risk factors, physical activity and fitness and adipocytokines in children throughout puberty. This review addresses the studies that have been conducted on adipocytokines and physical activity and their possible impact to metabolic syndrome in chilndren and adolescents.
Key words: metabolic syndrome, physical activity, physical fitness, adipocytokines, children and adolescents
Read article »
Zinc contribution to the regulation of glucose disposal, lipid metabolism and striated muscle contractions
Grażyna Lutosławska, Agnieszka Fornal-Urban
Zinc is the second, after iron, most abundant trace metal in the human body. In living systems zinc performs three categories of functions- catalytic, structural and regulatory. Zinc homeostasis is tightly regulated by zinc bioavailability and expression of specific zinc transporters in cell membranes and cellular organelles of alimentary tract, brain, muscle, pancreas and other tissues. In the literature there are numerous studies concerning zinc contribution to metabolic processes such as cell signaling, insulin sensitivity, antioxidant protection and lipid/ lipoprotein turnover. Zinc deficiency, common in developing countries, is detrimental for health causing growth retardation, decreased immunocompetence, anorexia, skin lesions, bleeding tendency, reproductive abnormalities and skeletal defects. In Western countries latent zinc deficiency is observed in about 12% of the population, however, its diagnosis is difficult due to the lack of reliable and simple methods evaluating human zinc status. Depressed zinc status is noted in type 2 diabetes and atherosclerosis, but data concerning beneficial effects of zinc supplementation in humans are equivocal. On the other hand, animal studies indicate that zinc enhances the phosphorylation of insulin-receptor substrates to activate a series of signal transductions that increase glucose uptake in insulin-sensitive cells and inhibits lipolysis in adipose tissue. Furthermore, zinc probably directly affects lipid metabolism since its deficiency down-regulates fatty acid utilization in mitochondria and peroxisomes and up regulates lipid synthesis affecting the expression of genes encoding enzymes contributing to liver lipid homeostasis. It is well documented that zinc plays a substantial role in muscle morphology and contraction in vitro, but it also affects performance in vivo. In physically active subjects dietary zinc deficiency was found in triathletes of both sexes and in female athletes engaged in sport focused on leanness. Thus, there is no need for zinc supplementation in all athletes. On the other hand, zinc supplementation if needed has to be carefully monitored due to detrimental effects of zinc excess on iron and copper absorption, and possibly energy metabolism.
Key words: zinc homeostasis, zinc deficiency, insulin sensitivity, lipids, striated muscle
Read article »
Gender differences after downhill running for voluntary isometric contractions of knee extensor muscles using surface EMG
Mark ET. Willems), Simon R. Northcott
Introduction: We examined gender differences for performance and surface electromyograms (sEMG) of knee extensors 1hr after downhill running.
Methods: Maximal voluntary isometric force (MVIF) and sEMG of vastus lateralis (VL) and vastus medialis (VM) muscles during 50%MVIF were measured in 8 males (22±4yr, 75.8±6.1kg, 179.2.0±5.0cm) and 8 females (27±8yr, 60.8±7.2kg, 166.3±5.0cm) before and 1 hr after downhill running [(5x8 min, -12%, 60%Vmax (females: 7.7±0.9km·h-1, males: 10.4±0.5km·h-1)].
Results: Males had higher MVIF values (674.3±59.8N versus 480.6±49.9N, P<0.001) and longer endurance times during 50%MVIF than females (78.7±24.1s versus 57.2±12.6s, P<0.05) before downhill running. After downhill running, MVIF deficits were similar (males: 11.7±7.2%, females: 7.5±7.7%) with no changes in endurance times during 50%MVIF. After the downhill run, there was a trend in females, but not males, of an increased ratio for the root mean square (RMS) values of the VL and VM muscles during MVIF testing by 23% (P=0.054). After the downhill run, females, but not males, lowered during 50%MVIF the change in RMS for VM from 48±32% to 30±31% and for VL from 36±23% to 21±18% (P<0.05). For males, a trend was observed for the change in median frequency in VL during 50%MVIF (P=0.05). After downhill running, females, altered the vastus medialis and vastus lateralis contributions to maximal isometric force production and the activity pattern of these muscles during submaximal isometric fatigue.
Conclusion: Acute neuromuscular adaptations after downhill running occur during voluntary isometric contractions of knee extensor muscles in females, but not in males.
Key words: Downhill running, skeletal muscle, electromyography, isometric contractions, muscle injury
Read article »
Assessment of maximal lactate steady state in elite female kayakers
Vasileios Diafas, Konstantinos Chrysikopoulos, Vasiliki Diamanti, Sokratis Kaloupsis
Introduction: Endurance training at an exercise intensity level reaching a maximal lactate steady state (MLSS) may result in increase in exercise adaptation while minimizing the risk of overtraining. Measuring MLSS in the laboratory is labor intensive; however, time trial events are relatively simple and often completed in endurance sports.
Methods: To determine whether a relationship between the average workload during a 6 km kayaking time trial and MLSS workload exists, female elite kayakers (age: 22.9 ± 1.9 yrs, VO2 peak: 46.3 ± 2.8 ml/kg/min, N = 23) underwent a maximal power output test on the kayak ergometer (max power: 259 ± 16 W), and MLSS was determined by using 30 min constant workload bouts of kayaking (mean MLSS: 2.64 ± 0.12 mmol/l). Subsequently, subjects completed a 6 km time trial to determine time and mean power.
Results: A significant relationship was found between mean power output and MLSS workload (r2 = 0.853, p < .001). Mean power output during the 6 km time trial (214 ± 12 W) was greater than the average MLSS power output (168 ± 8 W). Utilizing the regression equation: y = 0.7429x + 10.913, where x = mean 6 km time trial workload and y = MLSS workload, individual MLSS intensity can be predicted. For kayakers, while the time to complete a 6 km time trial decreases, MLSS workload increases. Conclusions: The results suggest that training to improve MLSS workload may improve a 6 km time trial performance.
Key words: kayaking, MLSS, threshold, time trial
Read article »
Indexed in: SportDiscus; EMBASE/Excerpta Medica; Index Copernicus
Rehabilitation and recovery training after snowboard accidents
Medicina Sportiva 2009 vol. 13, Issue 1
Copyright ® 2008 Medicina Sportiva
Thomas Kuepper, Nicola Huber, Nikolaus Netzer, Volker Schoeffl
Read article »
Circuit based deep water running improves cardiovascular fitness, strength and abdominal obesity in older, overweight women. Aquatic exercise intervention in older adults
Kimberley Meredith-Jones, Michael Legge, Lynnette M. Jones
Read article »
The influence of physical activity on body composition and the level of student’s flexibility
Tomasz Boraczyński, Lola Brygida Boraczyńska, Jerzy Urniaż
Read article »
An analysis of relations between a selfassessment of health and active life-style
Andrzej Knapik, Edward Saulicz, Michał Kuszewski, Ryszard Plinta
Read article »
Metabolic syndrome, physical activity and adipocytokines in children and adolescents
Toivo Jürimäe, Jaak Jürimäe, Jarek Mäestu
Read article »
Zinc contribution to the regulation of glucose disposal, lipid metabolism and striated muscle contractions
Grażyna Lutosławska, Agnieszka Fornal-Urban
Read article »
Gender differences after downhill running for voluntary isometric contractions of knee extensor muscles using surface EMG
Mark ET. Willems, Simon R. Northcott
Read article »
ASSESSMENT OF MAXIMAL LACTATE STEADY STATE IN ELITE FEMALE KAYAKERS
Vasileios Diafas, Konstantinos Chrysikopoulos, Vasiliki Diamanti, Sokratis Kaloupsis
Read article »
Rehabilitation and recovery training after snowboard accidents
Thomas Kuepper, Nicola Huber, Nikolaus Netzer, Volker Schoeffl
Objective: We aim to optimize specific recovery training with special regard to the style of snowboarding performed by the victims.
Background: With increasing popularity of snowboarding, accidents and injuries happen more often, but until now there is little data on sports specific recovery. Consequently physiotherapy is often performed with “standard” procedures which don’t take into account specific demands of snowboarding in general or the special demands of the different disciplines of snowboarding.
Material and Methods: Prospective observation of the course and result of rehabilitation performed according to the scheme described (open trial, n = 16). The paper also reviews the literature about the topic with special regard to the German literature, which is less easy accessible for the international reader.
Conclusions & Clinical advantages: All victims except one with spinal trauma recovered completely and went snowboarding the following season (some of them also for competitions). Recovery training of patients suffering from snowboard accidents should be started as soon as possible and sports specific demands should be taken into account. Optimal teamwork between the physician, the physiotherapist, the patient and the coach is necessary to optimize the results.
Key words: snowboard accidents, training, rehabilitation, winter sports
Read article »
Circuit based deep water running improves cardiovascular fitness, strength and abdominal obesity in older, overweight women. Aquatic exercise intervention in older adults
Kimberley Meredith-Jones, Michael Legge, Lynnette M. Jones
Introduction: Sedentary habits are associated with an increased risk of numerous chronic diseases; however, the type of exercise that may be most beneficial to improve health is still unclear. Water based exercise is rapidly growing in popularity as individuals, such as the elderly or the obese, can exercise at relatively high levels of intensity while imposing minimal strain on joints. However, little research has been conducted substantiating the health benefits of exercise in this medium.
Aim of the study: The purpose of this study was to evaluate the effects of a circuit based deep water running exercise program on aerobic capacity (VO2peak), strength and abdominal obesity in older, overweight/obese women
Materials and Methods: The participants (mean ± SD age 59 ± 9 years, BMI 33 ± 5 kg/m2, n=18) took part in a circuit based deep water running program with continuous deep water running (70-75% HRpeak) interspersed with 90 seconds of resistance exercises for 12 weeks, 60 min.day-1and 3 days.week-1.
Results: There were significant increases (p<.05) in VO2peak, (1.37 ± 0.10 vs 1.51 ± 0.08 L·min-1), and muscle strength (upper body 20 ± 7.1%, knee flexion 33 ± 7.9%, knee extension 32 ± 17.9%). There were significant reductions (p<.05) in waist circumference (105 ± 2.5 vs 100 ± 2.6 cm) and waist-hip ratio (0.90 ± 0.01 vs 0.87 ± 0.01).
Conclusions: These results indicate circuit based deep water running can elicit significant improvements in cardiorespiratory fitness, strength and abdominal obesity.
Keywords: cardiovascular disease, aquatic exercise, obesity
Read article »
The influence of physical activity on body composition and the level of student’s flexibility
Tomasz Boraczyński, Lola Brygida Boraczyńska, Jerzy Urniaż
Introduction. The purpose of the study was to assess the impact of physical activity on the body ingredients and the level of flexibility among students with various levels of physical activity.
Material and methods. The study involved 235 physical education students and 142 physiotherapy students (171 females and 206 males). The results provided information regarding their levels of physical activity. Their body ingredients were determined with the use of a Tanita BC 418 MA analyser. Their level of flexibility was assessed using the Modified Sit-and-Reach Test.
Results. The results of the study demonstrated a significantly lower body mass, lower fat content, lower value of the BMI index as well as a significantly higher level of flexibility (p<0.001) among students of physical education, compared to the students of physiotherapy.
Conclusions. The results indicate a positive impact of increased physical activity on the correct body mass as well as a very good level of flexibility.
Key words: body composition, flexibility, students
Read article »
An analysis of relations between a selfassessment of health and active life-style
Andrzej Knapik, Edward Saulicz, Michał Kuszewski, Ryszard Plinta
Introduction: Hypokinesis – a deficit in mobile activity, is thought to be one of the main causes of the appearance and development of the so called ‘diseases of civilization’. Optimising the level of activity against the needs is a complex issue. It requires taking into account different kinds of activity, their determinants, and correlations with various lifestyles as well as the impact on health. A diagnosis of the relation between the various kinds of activity and health can constitute the starting point for implementing application methods.
Objective: The objective was to define the impact of the different kinds of activity on the various factors and components of the self-assessment of health.
Materials and methods: 154 men aged 30-60 were tested with the application of sociometric methods. The following questionnaires were applied: self-assessment of activity levels (SEWL) and self-assessment of health (SF-36). A statistical analysis of the results of the research included the computation of Spearman’s indicators of correlation between the level of the various kinds of activity and the factors and components of health. Participants of the research were divided into quartiles according to the level of their self-assessment of health. Statistical description was done and the ANOVA analysis was made of variants between the top and bottom groups with the aim to finding the differences pertaining to the various kinds of activity. In each case p≤0.05 was assumed as the level of the significance of differences.
Results: Significant correlations between the physical and mental components of health and the sports factor were observed. In case of health factors, the correlations were observed with regards to physical mobility, activity and health in general also in relation to sports factor. Statistically relevant were the relations between physical mobility and activity (SEWL indicator) and also activity (spare time indicator). The ANOVA analysis of variants showed the statistical importance of the differences between the top and bottom quartiles of health self-assessment with regards to sports indicator and SEWL indicator.
Conclusions: The results of the research lead to the conclusion that physical activity plays a significant role in shaping the self-assessment of health, both its physical and mental components. The deciding factor seems to be the activity of a sporting nature which most strongly influences factors of health such as physical mobility, activity and general well-being.
Key words: hypokinesis, mobile activity, self-assessment of health
Read article »
Metabolic syndrome, physical activity and adipocytokines in children and adolescents
Toivo Jürimäe, Jaak Jürimäe, Jarek Mäestu
Metabolic syndrome is a major risk factor for cardiovascular diseases and type 2 diabetes. Biomarkers of the metabolic syndrome develop early in life and can be predictive of atherosclerotic processes in adulthood. Low physical activity levels in children, with a possible modulating effect of cardiorespiratory fitness have been associated with a higher clustering of metabolic risk factors in adults. All these markers are highly influenced by physical activity level and physical fitness. Evidence suggests that there is a significant genetic component involved in physical fitness phenotypes. However, there are very limited data in the literature on genetic predisposition to physical activity level in children and adolescents. Adipose tissue has now been considered as an endocrine organ that produces many molecules called adipocytokines. Leptin and adiponectin are most studied regarding the metabolic risk factors, while adiponectin is considered as one of the most promising biochemical marker to characterize metabolic syndrome in adults. There are yet no studies that have longitudinally investigated the complex changes of the metabolic risk factors, physical activity and fitness and adipocytokines in children throughout puberty. This review addresses the studies that have been conducted on adipocytokines and physical activity and their possible impact to metabolic syndrome in chilndren and adolescents.
Key words: metabolic syndrome, physical activity, physical fitness, adipocytokines, children and adolescents
Read article »
Zinc contribution to the regulation of glucose disposal, lipid metabolism and striated muscle contractions
Grażyna Lutosławska, Agnieszka Fornal-Urban
Zinc is the second, after iron, most abundant trace metal in the human body. In living systems zinc performs three categories of functions- catalytic, structural and regulatory. Zinc homeostasis is tightly regulated by zinc bioavailability and expression of specific zinc transporters in cell membranes and cellular organelles of alimentary tract, brain, muscle, pancreas and other tissues. In the literature there are numerous studies concerning zinc contribution to metabolic processes such as cell signaling, insulin sensitivity, antioxidant protection and lipid/ lipoprotein turnover. Zinc deficiency, common in developing countries, is detrimental for health causing growth retardation, decreased immunocompetence, anorexia, skin lesions, bleeding tendency, reproductive abnormalities and skeletal defects. In Western countries latent zinc deficiency is observed in about 12% of the population, however, its diagnosis is difficult due to the lack of reliable and simple methods evaluating human zinc status. Depressed zinc status is noted in type 2 diabetes and atherosclerosis, but data concerning beneficial effects of zinc supplementation in humans are equivocal. On the other hand, animal studies indicate that zinc enhances the phosphorylation of insulin-receptor substrates to activate a series of signal transductions that increase glucose uptake in insulin-sensitive cells and inhibits lipolysis in adipose tissue. Furthermore, zinc probably directly affects lipid metabolism since its deficiency down-regulates fatty acid utilization in mitochondria and peroxisomes and up regulates lipid synthesis affecting the expression of genes encoding enzymes contributing to liver lipid homeostasis. It is well documented that zinc plays a substantial role in muscle morphology and contraction in vitro, but it also affects performance in vivo. In physically active subjects dietary zinc deficiency was found in triathletes of both sexes and in female athletes engaged in sport focused on leanness. Thus, there is no need for zinc supplementation in all athletes. On the other hand, zinc supplementation if needed has to be carefully monitored due to detrimental effects of zinc excess on iron and copper absorption, and possibly energy metabolism.
Key words: zinc homeostasis, zinc deficiency, insulin sensitivity, lipids, striated muscle
Read article »
Gender differences after downhill running for voluntary isometric contractions of knee extensor muscles using surface EMG
Mark ET. Willems), Simon R. Northcott
Introduction: We examined gender differences for performance and surface electromyograms (sEMG) of knee extensors 1hr after downhill running.
Methods: Maximal voluntary isometric force (MVIF) and sEMG of vastus lateralis (VL) and vastus medialis (VM) muscles during 50%MVIF were measured in 8 males (22±4yr, 75.8±6.1kg, 179.2.0±5.0cm) and 8 females (27±8yr, 60.8±7.2kg, 166.3±5.0cm) before and 1 hr after downhill running [(5x8 min, -12%, 60%Vmax (females: 7.7±0.9km·h-1, males: 10.4±0.5km·h-1)].
Results: Males had higher MVIF values (674.3±59.8N versus 480.6±49.9N, P<0.001) and longer endurance times during 50%MVIF than females (78.7±24.1s versus 57.2±12.6s, P<0.05) before downhill running. After downhill running, MVIF deficits were similar (males: 11.7±7.2%, females: 7.5±7.7%) with no changes in endurance times during 50%MVIF. After the downhill run, there was a trend in females, but not males, of an increased ratio for the root mean square (RMS) values of the VL and VM muscles during MVIF testing by 23% (P=0.054). After the downhill run, females, but not males, lowered during 50%MVIF the change in RMS for VM from 48±32% to 30±31% and for VL from 36±23% to 21±18% (P<0.05). For males, a trend was observed for the change in median frequency in VL during 50%MVIF (P=0.05). After downhill running, females, altered the vastus medialis and vastus lateralis contributions to maximal isometric force production and the activity pattern of these muscles during submaximal isometric fatigue.
Conclusion: Acute neuromuscular adaptations after downhill running occur during voluntary isometric contractions of knee extensor muscles in females, but not in males.
Key words: Downhill running, skeletal muscle, electromyography, isometric contractions, muscle injury
Read article »
Assessment of maximal lactate steady state in elite female kayakers
Vasileios Diafas, Konstantinos Chrysikopoulos, Vasiliki Diamanti, Sokratis Kaloupsis
Introduction: Endurance training at an exercise intensity level reaching a maximal lactate steady state (MLSS) may result in increase in exercise adaptation while minimizing the risk of overtraining. Measuring MLSS in the laboratory is labor intensive; however, time trial events are relatively simple and often completed in endurance sports.
Methods: To determine whether a relationship between the average workload during a 6 km kayaking time trial and MLSS workload exists, female elite kayakers (age: 22.9 ± 1.9 yrs, VO2 peak: 46.3 ± 2.8 ml/kg/min, N = 23) underwent a maximal power output test on the kayak ergometer (max power: 259 ± 16 W), and MLSS was determined by using 30 min constant workload bouts of kayaking (mean MLSS: 2.64 ± 0.12 mmol/l). Subsequently, subjects completed a 6 km time trial to determine time and mean power.
Results: A significant relationship was found between mean power output and MLSS workload (r2 = 0.853, p < .001). Mean power output during the 6 km time trial (214 ± 12 W) was greater than the average MLSS power output (168 ± 8 W). Utilizing the regression equation: y = 0.7429x + 10.913, where x = mean 6 km time trial workload and y = MLSS workload, individual MLSS intensity can be predicted. For kayakers, while the time to complete a 6 km time trial decreases, MLSS workload increases. Conclusions: The results suggest that training to improve MLSS workload may improve a 6 km time trial performance.
Key words: kayaking, MLSS, threshold, time trial
Read article »