The effect of high volume stretch-shortening cycle exercise on muscle and connective tissue damage

Intense or rather prolonged exercises, especially stretch-shortening cycle type (various jumps, throws), induce muscle (Allen, 2008) and connective tissue damage (Buchanan & Marsh, 2002). Muscle damage is characterized by prolonged decrease in muscle contraction strength, swelling, stiffness, soreness and an increase in the level of muscle creatine kinase (CK) activity in the blood (Byrne et al., 2004; Chen et al., 2013; Nosaka & Clarkson, 1996; Skurvydas et al., 2011). These symptoms are widely accepted as indirect indicators of muscle damage (Clarkson & Hubal, 2002; Warren et al., 1999). The ultrastructural changes of myofibril sarcomere, desmin and other cytoskeleton proteins, ultrastructural changes in sarcolemma are directly visible by an electron microscope (Féasson et al., 2002; Hortobágyi et al., 1998; Lauritzen et al., 2009). The damage to the connective tissue is indicated by a change in the distorted tendon appearance, an increase in the number of immature cells and apoptotic cells, disorganized collagen bundles, increased proteoglycan content and neovascularization in the tendons, changes in the extracellular matrix. Adaptation of the human motor system to muscle damage is quite well researched, although adaptation mechanisms are still not clear. The effects of physical exercises on the structure and metabolism of connective tissue have been significantly less studied (Tardioli et al., 2012), although changes in connective tissue are documented in a rather detailed way histologically (Maffulli et al., 2000), biochemically (Waśkiewicz et al., 2012) and clinical practice (Grigg et al., 2009). Physical exercises can promote the development of the structural and functional properties of the tendons (Nelly Andarawis-Puri et al., 2015). The process of tendon reconstruction involves collagen synthesis and degradation, which begin immediately after physical exercise (Magnusson et al., 2010). Studies using animal models have shown that physical exercise leads to an increase in the number of cells in the tendons, in particular of stem origin, and in the activation of collagen synthesis (Zhang et al., 2010). Studies have also shown that changes in the tendon depend on the recovery period between physical exercises, and the absence of a recovery period stimulates tendon degeneration instead of adaptation (Ristolainen et al., 2014). Healthy tendons are less affected by physical activity, whereas damaged tendons become thicker (Fredberg, Bolvign, 2002; O’Connor et al., 2004). Stretch-shortening cycle exercises are widely used to improve the muscular strenght of athletes and healthy non-professional subjects (Markovic, 2007). These physical exercises are recommended to be used carefully because a high numbers of jumps / throws can lead to chronic fatigue and reduce the effectiveness of exercise (Seynnes et al., 2013). Extremely large eccentric concentric loads are believed to not only cause muscle damage but also adversely affect the structural integrity of the tendons and ligaments. In the first study, we investigated the impact of particularly high volume single bout exercise on the adaptation of the motor system, as the intensification of the training process raises the need to know the limits of safe physical activity. It is known that the cyclists’ quadriceps muscles do not perform eccentric work during the specific exercise in the sport (avoids damage), but long-distance runners’ thigh, calf and foot muscles often experience muscle damage during training and competition (Kuipers, 1989; Warhol et al., 1985). Fredberg et al. (2007) have hypothesized that tendon changes detected by ultrasound examination appear before they occur clinically and are therefore very important for the examination of the long-term adaptation of athletes (Couppe et al., 2008; Fahlström & Alfredson, 2010). Depending on the specialization of the sport, the sensitivity of not only the muscle, but also of the connective tissue damage may vary. So, in the second study, we investigated how different sports specializations affect the long-term adaptation of muscles and connective tissue to specific physical activity, and how the indices of muscle and connective tissue damage vary for athletes specializing in different sports while they perform single bout unconventional eccentric exercise of 100 jumps. Recent studies have shown that the motor system is sensitive to the strategy of increasing physical load (Kamandulis et al., 2011, 2012). Muscle damage can be avoided by consistently involving physical exercises and gradually increasing the volume and intensity of exercise as well as the range of motion (Kamandulis et al., 2011). The adaptation of the motor system is higher when we apply the strategy of rapid instead of gradual increase in physical load (Chen et al., 2013). Exercise frequency is another factor that should be considered when planning the training process. Regarding sports activities, maximal intensity eccentric-concentric exercises are performed no more than 2–3 times a week, with sufficient time for the recovery of the body. Sometimes coaches use high intensity exercise more often than three times a week, but for a relatively short time (a microcycle of 5–9 days). In this way, great fatigue and damage is caused deliberately in the hope of higher supercompensation during recovery. However, there is a lack of data in the literature on the effects of frequent jump training loads on changes in muscles and connective tissue. Chen and Hsieh (2001) found that daily, repetitive, maximal eccentric exercise of constant volume did not increase muscle damage and inflammation during the seven days of training. However, the peculiarities of adaptation of muscles and tendons when using the strategy of rapid increase in workload with a short period of time between exercises are not known. Aiming at establishing the impact of such strategy on the motor system, we performed a repeated 9-day increasing physical workload involving jumps. Research aim To establish the effect of high volume and frequent stretch-shortening cycle exercise as well as different sports specializations on muscle and connective tissue damage. Research objectives 1. To establish the effect of a high volume single bout stretch-shortening cycle exercise on muscle and connective tissue damage. 2. To establish the effect of a high volume single bout stretch-shortening cycle exercise on muscle and connective tissue damage for athletes of different specializations. 3. To establish the effect of frequenly performed gradually increasing stretch-shortening cycle exercise on muscle and connective tissue damage. Theoretical and practical significance So far, it has not been known whether such high volume eccentric concentric exercise is safe for muscles and connective tissues. Thus, according to the data presented in the dissertation, it can be argued that high volume single bout eccentric concentric physical exercise (200 jumps) induces moderate muscle damage in physically active men, but minimally changes the morphological parameters of the tendons and is relatively safe for completely healthy tendons, however, it can cause muscle soreness when initial signs of connective tissue (tendons, ligaments) damage are present. Sports specialization has a small effect on muscle sensitivity for damage, i.e. long-term concentric exercise (cycling) can lead to increased muscle soreness and sarcolemmal damage as compared to long-term eccentric-concentric exercises (long run races), but the sensitivity of tendons to damage tends to vary slightly. However, we do not recommend performing high volume eccentric-concentric physical exercises every day: although muscle and connective tissue damage is not high, i.e. training is relatively safe, but such training method is not very effective. CONCLUSIONS 1. The large volume single-bout stretch-shortening cycle (200 jumps) exercise induces moderate muscle damage in physically active males, but makes little change to the morphological characteristics of the tendons. The stretch-shortening cycle exercise of this volume is relatively safe for completely healthy tendons, but can provoke muscle soreness when there are primary signs of connective tissue (tendons, ligaments) damage. 2. The large volume single-bout stretch-shortening cycle (100 jumps) physical exercise causes moderate muscle damage to endurance athletes. Eccentrically-concentrically trained long-distance runners are less susceptible to muscle soreness and sarcolemmal damage than concentrically trained cyclists, but the differences in the torque of muscle contraction force are not significant between these groups. The thickness of the proximal part of the patella and the cross-sectional area of the distal part of the Achilles tendon in runners increased after 24 hours after performing jumps from the platform, but other morphological indices of the tendons did not change, indirectly confirming that a single bout, even high-volume unusual eccentric-concentric physical load causes minimal damage to the connective tissue. 3. Frequently repeated stretch-shortening cycle exercises cause moderate muscle damage, which especially increases while increasing the range of motion, but the changes in the connective tissue damage during this exercise are relatively negligible. At the time of recovery after such exercise, the height of the jump increases, but the maximal voluntary contaction torque and electrostimulation evoked muscle contraction torque remain at the same level as before the exercise. High volume stretch-shortening cycle exercises are fairly safe to be performed every day, as the muscle and connective tissue damage is not high; however, this method of training is not very effective

The effect of high volume stretch-shortening cycle exercise on muscle and connective tissue damage

Intense or rather prolonged exercises, especially stretch-shortening cycle type (various jumps, throws), induce muscle (Allen, 2008) and connective tissue damage (Buchanan & Marsh, 2002). Muscle damage is characterized by prolonged decrease in muscle contraction strength, swelling, stiffness, soreness and an increase in the level of muscle creatine kinase (CK) activity in the blood (Byrne et al., 2004; Chen et al., 2013; Nosaka & Clarkson, 1996; Skurvydas et al., 2011). These symptoms are widely accepted as indirect indicators of muscle damage (Clarkson & Hubal, 2002; Warren et al., 1999). The ultrastructural changes of myofibril sarcomere, desmin and other cytoskeleton proteins, ultrastructural changes in sarcolemma are directly visible by an electron microscope (Féasson et al., 2002; Hortobágyi et al., 1998; Lauritzen et al., 2009). The damage to the connective tissue is indicated by a change in the distorted tendon appearance, an increase in the number of immature cells and apoptotic cells, disorganized collagen bundles, increased proteoglycan content and neovascularization in the tendons, changes in the extracellular matrix. Adaptation of the human motor system to muscle damage is quite well researched, although adaptation mechanisms are still not clear. The effects of physical exercises on the structure and metabolism of connective tissue have been significantly less studied (Tardioli et al., 2012), although changes in connective tissue are documented in a rather detailed way histologically (Maffulli et al., 2000), biochemically (Waśkiewicz et al., 2012) and clinical practice (Grigg et al., 2009). Physical exercises can promote the development of the structural and functional properties of the tendons (Nelly Andarawis-Puri et al., 2015). The process of tendon reconstruction involves collagen synthesis and degradation, which begin immediately after physical exercise (Magnusson et al., 2010). Studies using animal models have shown that physical exercise leads to an increase in the number of cells in the tendons, in particular of stem origin, and in the activation of collagen synthesis (Zhang et al., 2010). Studies have also shown that changes in the tendon depend on the recovery period between physical exercises, and the absence of a recovery period stimulates tendon degeneration instead of adaptation (Ristolainen et al., 2014). Healthy tendons are less affected by physical activity, whereas damaged tendons become thicker (Fredberg, Bolvign, 2002; O’Connor et al., 2004). Stretch-shortening cycle exercises are widely used to improve the muscular strenght of athletes and healthy non-professional subjects (Markovic, 2007). These physical exercises are recommended to be used carefully because a high numbers of jumps / throws can lead to chronic fatigue and reduce the effectiveness of exercise (Seynnes et al., 2013). Extremely large eccentric concentric loads are believed to not only cause muscle damage but also adversely affect the structural integrity of the tendons and ligaments. In the first study, we investigated the impact of particularly high volume single bout exercise on the adaptation of the motor system, as the intensification of the training process raises the need to know the limits of safe physical activity. It is known that the cyclists’ quadriceps muscles do not perform eccentric work during the specific exercise in the sport (avoids damage), but long-distance runners’ thigh, calf and foot muscles often experience muscle damage during training and competition (Kuipers, 1989; Warhol et al., 1985). Fredberg et al. (2007) have hypothesized that tendon changes detected by ultrasound examination appear before they occur clinically and are therefore very important for the examination of the long-term adaptation of athletes (Couppe et al., 2008; Fahlström & Alfredson, 2010). Depending on the specialization of the sport, the sensitivity of not only the muscle, but also of the connective tissue damage may vary. So, in the second study, we investigated how different sports specializations affect the long-term adaptation of muscles and connective tissue to specific physical activity, and how the indices of muscle and connective tissue damage vary for athletes specializing in different sports while they perform single bout unconventional eccentric exercise of 100 jumps. Recent studies have shown that the motor system is sensitive to the strategy of increasing physical load (Kamandulis et al., 2011, 2012). Muscle damage can be avoided by consistently involving physical exercises and gradually increasing the volume and intensity of exercise as well as the range of motion (Kamandulis et al., 2011). The adaptation of the motor system is higher when we apply the strategy of rapid instead of gradual increase in physical load (Chen et al., 2013). Exercise frequency is another factor that should be considered when planning the training process. Regarding sports activities, maximal intensity eccentric-concentric exercises are performed no more than 2–3 times a week, with sufficient time for the recovery of the body. Sometimes coaches use high intensity exercise more often than three times a week, but for a relatively short time (a microcycle of 5–9 days). In this way, great fatigue and damage is caused deliberately in the hope of higher supercompensation during recovery. However, there is a lack of data in the literature on the effects of frequent jump training loads on changes in muscles and connective tissue. Chen and Hsieh (2001) found that daily, repetitive, maximal eccentric exercise of constant volume did not increase muscle damage and inflammation during the seven days of training. However, the peculiarities of adaptation of muscles and tendons when using the strategy of rapid increase in workload with a short period of time between exercises are not known. Aiming at establishing the impact of such strategy on the motor system, we performed a repeated 9-day increasing physical workload involving jumps. Research aim To establish the effect of high volume and frequent stretch-shortening cycle exercise as well as different sports specializations on muscle and connective tissue damage. Research objectives 1. To establish the effect of a high volume single bout stretch-shortening cycle exercise on muscle and connective tissue damage. 2. To establish the effect of a high volume single bout stretch-shortening cycle exercise on muscle and connective tissue damage for athletes of different specializations. 3. To establish the effect of frequenly performed gradually increasing stretch-shortening cycle exercise on muscle and connective tissue damage. Theoretical and practical significance So far, it has not been known whether such high volume eccentric concentric exercise is safe for muscles and connective tissues. Thus, according to the data presented in the dissertation, it can be argued that high volume single bout eccentric concentric physical exercise (200 jumps) induces moderate muscle damage in physically active men, but minimally changes the morphological parameters of the tendons and is relatively safe for completely healthy tendons, however, it can cause muscle soreness when initial signs of connective tissue (tendons, ligaments) damage are present. Sports specialization has a small effect on muscle sensitivity for damage, i.e. long-term concentric exercise (cycling) can lead to increased muscle soreness and sarcolemmal damage as compared to long-term eccentric-concentric exercises (long run races), but the sensitivity of tendons to damage tends to vary slightly. However, we do not recommend performing high volume eccentric-concentric physical exercises every day: although muscle and connective tissue damage is not high, i.e. training is relatively safe, but such training method is not very effective. CONCLUSIONS 1. The large volume single-bout stretch-shortening cycle (200 jumps) exercise induces moderate muscle damage in physically active males, but makes little change to the morphological characteristics of the tendons. The stretch-shortening cycle exercise of this volume is relatively safe for completely healthy tendons, but can provoke muscle soreness when there are primary signs of connective tissue (tendons, ligaments) damage. 2. The large volume single-bout stretch-shortening cycle (100 jumps) physical exercise causes moderate muscle damage to endurance athletes. Eccentrically-concentrically trained long-distance runners are less susceptible to muscle soreness and sarcolemmal damage than concentrically trained cyclists, but the differences in the torque of muscle contraction force are not significant between these groups. The thickness of the proximal part of the patella and the cross-sectional area of the distal part of the Achilles tendon in runners increased after 24 hours after performing jumps from the platform, but other morphological indices of the tendons did not change, indirectly confirming that a single bout, even high-volume unusual eccentric-concentric physical load causes minimal damage to the connective tissue. 3. Frequently repeated stretch-shortening cycle exercises cause moderate muscle damage, which especially increases while increasing the range of motion, but the changes in the connective tissue damage during this exercise are relatively negligible. At the time of recovery after such exercise, the height of the jump increases, but the maximal voluntary contaction torque and electrostimulation evoked muscle contraction torque remain at the same level as before the exercise. High volume stretch-shortening cycle exercises are fairly safe to be performed every day, as the muscle and connective tissue damage is not high; however, this method of training is not very effective

Didelės apimties ekscentrinio-koncentrinio fizinio krūvio poveikis raumenų ir jungiamojo audinio pažeidai

Intense or rather prolonged exercises, especially stretch-shortening cycle type (various jumps, throws), induce muscle (Allen, 2008) and connective tissue damage (Buchanan & Marsh, 2002). Muscle damage is characterized by prolonged decrease in muscle contraction strength, swelling, stiffness, soreness and an increase in the level of muscle creatine kinase (CK) activity in the blood (Byrne et al., 2004; Chen et al., 2013; Nosaka & Clarkson, 1996; Skurvydas et al., 2011). These symptoms are widely accepted as indirect indicators of muscle damage (Clarkson & Hubal, 2002; Warren et al., 1999). The ultrastructural changes of myofibril sarcomere, desmin and other cytoskeleton proteins, ultrastructural changes in sarcolemma are directly visible by an electron microscope (Féasson et al., 2002; Hortobágyi et al., 1998; Lauritzen et al., 2009). The damage to the connective tissue is indicated by a change in the distorted tendon appearance, an increase in the number of immature cells and apoptotic cells, disorganized collagen bundles, increased proteoglycan content and neovascularization in the tendons, changes in the extracellular matrix. Adaptation of the human motor system to muscle damage is quite well researched, although adaptation mechanisms are still not clear. The effects of physical exercises on the structure and metabolism of connective tissue have been significantly less studied (Tardioli et al., 2012), although changes in connective tissue are documented in a rather detailed way histologically (Maffulli et al., 2000), biochemically (Waśkiewicz et al., 2012) and clinical practice (Grigg et al., 2009). Physical exercises can promote the development of the structural and functional properties of the tendons (Nelly Andarawis-Puri et al., 2015). The process of tendon reconstruction involves collagen synthesis and degradation, which begin immediately after physical exercise (Magnusson et al., 2010). Studies using animal models have shown that physical exercise leads to an increase in the number of cells in the tendons, in particular of stem origin, and in the activation of collagen synthesis (Zhang et al., 2010). Studies have also shown that changes in the tendon depend on the recovery period between physical exercises, and the absence of a recovery period stimulates tendon degeneration instead of adaptation (Ristolainen et al., 2014). Healthy tendons are less affected by physical activity, whereas damaged tendons become thicker (Fredberg, Bolvign, 2002; O’Connor et al., 2004). Stretch-shortening cycle exercises are widely used to improve the muscular strenght of athletes and healthy non-professional subjects (Markovic, 2007). These physical exercises are recommended to be used carefully because a high numbers of jumps / throws can lead to chronic fatigue and reduce the effectiveness of exercise (Seynnes et al., 2013). Extremely large eccentric concentric loads are believed to not only cause muscle damage but also adversely affect the structural integrity of the tendons and ligaments. In the first study, we investigated the impact of particularly high volume single bout exercise on the adaptation of the motor system, as the intensification of the training process raises the need to know the limits of safe physical activity. It is known that the cyclists’ quadriceps muscles do not perform eccentric work during the specific exercise in the sport (avoids damage), but long-distance runners’ thigh, calf and foot muscles often experience muscle damage during training and competition (Kuipers, 1989; Warhol et al., 1985). Fredberg et al. (2007) have hypothesized that tendon changes detected by ultrasound examination appear before they occur clinically and are therefore very important for the examination of the long-term adaptation of athletes (Couppe et al., 2008; Fahlström & Alfredson, 2010). Depending on the specialization of the sport, the sensitivity of not only the muscle, but also of the connective tissue damage may vary. So, in the second study, we investigated how different sports specializations affect the long-term adaptation of muscles and connective tissue to specific physical activity, and how the indices of muscle and connective tissue damage vary for athletes specializing in different sports while they perform single bout unconventional eccentric exercise of 100 jumps. Recent studies have shown that the motor system is sensitive to the strategy of increasing physical load (Kamandulis et al., 2011, 2012). Muscle damage can be avoided by consistently involving physical exercises and gradually increasing the volume and intensity of exercise as well as the range of motion (Kamandulis et al., 2011). The adaptation of the motor system is higher when we apply the strategy of rapid instead of gradual increase in physical load (Chen et al., 2013). Exercise frequency is another factor that should be considered when planning the training process. Regarding sports activities, maximal intensity eccentric-concentric exercises are performed no more than 2–3 times a week, with sufficient time for the recovery of the body. Sometimes coaches use high intensity exercise more often than three times a week, but for a relatively short time (a microcycle of 5–9 days). In this way, great fatigue and damage is caused deliberately in the hope of higher supercompensation during recovery. However, there is a lack of data in the literature on the effects of frequent jump training loads on changes in muscles and connective tissue. Chen and Hsieh (2001) found that daily, repetitive, maximal eccentric exercise of constant volume did not increase muscle damage and inflammation during the seven days of training. However, the peculiarities of adaptation of muscles and tendons when using the strategy of rapid increase in workload with a short period of time between exercises are not known. Aiming at establishing the impact of such strategy on the motor system, we performed a repeated 9-day increasing physical workload involving jumps. Research aim To establish the effect of high volume and frequent stretch-shortening cycle exercise as well as different sports specializations on muscle and connective tissue damage. Research objectives 1. To establish the effect of a high volume single bout stretch-shortening cycle exercise on muscle and connective tissue damage. 2. To establish the effect of a high volume single bout stretch-shortening cycle exercise on muscle and connective tissue damage for athletes of different specializations. 3. To establish the effect of frequenly performed gradually increasing stretch-shortening cycle exercise on muscle and connective tissue damage. Theoretical and practical significance So far, it has not been known whether such high volume eccentric concentric exercise is safe for muscles and connective tissues. Thus, according to the data presented in the dissertation, it can be argued that high volume single bout eccentric concentric physical exercise (200 jumps) induces moderate muscle damage in physically active men, but minimally changes the morphological parameters of the tendons and is relatively safe for completely healthy tendons, however, it can cause muscle soreness when initial signs of connective tissue (tendons, ligaments) damage are present. Sports specialization has a small effect on muscle sensitivity for damage, i.e. long-term concentric exercise (cycling) can lead to increased muscle soreness and sarcolemmal damage as compared to long-term eccentric-concentric exercises (long run races), but the sensitivity of tendons to damage tends to vary slightly. However, we do not recommend performing high volume eccentric-concentric physical exercises every day: although muscle and connective tissue damage is not high, i.e. training is relatively safe, but such training method is not very effective. CONCLUSIONS 1. The large volume single-bout stretch-shortening cycle (200 jumps) exercise induces moderate muscle damage in physically active males, but makes little change to the morphological characteristics of the tendons. The stretch-shortening cycle exercise of this volume is relatively safe for completely healthy tendons, but can provoke muscle soreness when there are primary signs of connective tissue (tendons, ligaments) damage. 2. The large volume single-bout stretch-shortening cycle (100 jumps) physical exercise causes moderate muscle damage to endurance athletes. Eccentrically-concentrically trained long-distance runners are less susceptible to muscle soreness and sarcolemmal damage than concentrically trained cyclists, but the differences in the torque of muscle contraction force are not significant between these groups. The thickness of the proximal part of the patella and the cross-sectional area of the distal part of the Achilles tendon in runners increased after 24 hours after performing jumps from the platform, but other morphological indices of the tendons did not change, indirectly confirming that a single bout, even high-volume unusual eccentric-concentric physical load causes minimal damage to the connective tissue. 3. Frequently repeated stretch-shortening cycle exercises cause moderate muscle damage, which especially increases while increasing the range of motion, but the changes in the connective tissue damage during this exercise are relatively negligible. At the time of recovery after such exercise, the height of the jump increases, but the maximal voluntary contaction torque and electrostimulation evoked muscle contraction torque remain at the same level as before the exercise. High volume stretch-shortening cycle exercises are fairly safe to be performed every day, as the muscle and connective tissue damage is not high; however, this method of training is not very effective

The Effect of intense drop jumps from a platform physical exercise on muscle and connective tissue damage

Intensyvūs arba labai ilgai trunkantys, ypač ekscentriniai-koncentriniai, pratimai (įvairūs šuoliai, metimai) sukelia raumenų pažaidą. Dažnai treneriai, siekdami sportinio rezultato, taiko ypač didelės apimties fizinius krūvius, taip sąmoningai sukeldami didelę pažaidą ir tikėdamiesi didesnės superkompensacijos atsigavimo metu. Tokius fizinius krūvius rekomenduojama taikyti atsargiai, nes didelis kiekis šuolių / metimų gali sukelti ilgai trunkantį nuovargį ir mažina pratybų efektyvumą. Gerokai mažiau tirtas ekscentrinių-koncentrinių pratimų poveikis jungiamojo audinio pažaidai, nors sausgyslių pokyčiai gana išsamiai dokumentuoti histologiškai, biochemiškai ir klinikinėje praktikoje. Šio tyrimo tikslas – nustatyti didelės apimties vienkartinio ekscentrinio-koncentrinio fizinio krūvio įtaką raumenų ir jungiamojo audinio pažaidai. Tyrime dalyvavo 11 sveikų, fiziškai aktyvių, netreniruotų vyrų (amžius 29,8 ± 9,3 metų; kūno svoris 81,7 ± 5,8 kg; ūgis 181,2 ± 7,4 cm). Tiriamieji atliko 200 šuolių nuo pakylos fizinį krūvį (4 serijos po 50). Prieš šuolius ir po jų izokinetiniu dinamometru buvo matuojama šlaunies keturgalvio raumens maksimali valinga ir elektrostimuliacijos sukelta jėga bei ultragarsiniu tyrimu – kelio girnelės ir Achilo sausgyslės storis ir skerspjūvio plotas. Taip pat buvo vertinamas kreatinkinazės (CK) aktyvumas kraujo plazmoje bei raumenų skausmas. Tyrimo rezultatai parodė, kad 200 šuolių nuo pakylos fizinis krūvis sukelia: 1) keturgalvio šlaunies raumens maksimalios valingos ir elektrostimuliacija sukeltos jėgos sumažėjimą ir ilgai trunkantį atsigavimą; 2) keturgalvio šlaunies raumens skausmą ir CK aktyvumo padidėjimą kraujo plazmoje; 3) Achilo ir kelio girnelės sausgyslių storio ir skerspjūvio ploto sumažėjimą ir nedidelius individualius sausgyslių pažaidos požymius iškart po šuolių, tačiau pokyčiai išnyksta praėjus 24 val. po krūvio. Išvada. Didelės apimties vienkartinis ekscentrinis-koncentrinis (200 šuolių nuo pakylos) fizinis krūvis sukelia vidutinio dydžio fiziškai aktyvių vyrų raumenų pažaidą, tačiau mažai keičia sausgyslių morfologinius rodiklius. Tokio dydžio ekscentrinis-koncentrinis fizinis krūvis yra santykinai saugus visiškai sveikoms sausgyslėms, tačiau gali išprovokuoti skausmą esant pirminiams jungiamojo audinio pažaidos požymiams.Intensive or prolonged, eccentric-concentric exercises (various jumps, throws) in particular, cause muscle damage. Aiming at achieving a sports result, coaches often use intense physical exercise, thus consciously causing great damage expecting a higher supercompensation at the time of recovery. Such physical exercise is recommended to be used cautiously because high numbers of jumps/throws can result in prolonged fatigue and reduce training effectiveness. Effects of eccentric-concentric exercises on connective tissue damage have been researched less, although changes in tendons have been well documented histologically, biochemically and in clinical practice. The purpose of this study was to determine the effect of intense single bout eccentric-concentric physical exercise on muscle and connective tissue damage. The study involved 11 healthy, physically active, untrained men (age 29.8 ± 9.3 years, body weight 81.7 ± 5.8 kg, height 181.2 ± 7.4 cm). The subjects performed 200 drop jumps from the platform (4 series, 50 repetitions in each of them). Before and after the drop jumps, maximal voluntary and electrically evoked torque of the leg quadriceps muscle was measured using the isokinetic dynamometer, and the thickness and cross-sectional area of the knee patellar and Achilles tendon were measured applying ultrasonography. Plasma creatine kinase (CK) activity and muscle soreness were evaluated as well. The results of the study showed that physical exercise of 200 drop jumps from the platform causes: (1) reduction in the maximal voluntary and electrically evoked torque of the quadriceps muscle and long-lasting recovery; (2) increase in quadriceps muscle soreness and CK activity in blood plasma; (3) decrease in the thickness and sectional area of the Achilles and knee patellar tendons and slight indications of individual tendon damage immediately after the drop jumps, but the changes disappear after 24 hours. Conclusion: Intense single bout eccentric-concentric (200 drop jumps from a platform) physical exercise causes moderate muscle damage in physically active men, but minor changes in the morphological indicators of the tendons. The eccentric-concentric physical exercise of this magnitude is relatively safe for completely healthy tendons, but it can cause soreness with initial indications of connective tissue damage

Intratendinous Air Phenomenon: A New Ultrasound Marker of Tendon Damage?

Purpose: To explore the presence of intratendinous air in physically active males after different types of strenuous physical exercise.Materials and Methods: To detect foci (air bubbles) in the quadriceps femoris tendon (QFT) and the proximal and distal parts of the patellar tendon, ultrasound examination was performed under two conditions: (1) after high-intensity cycling on a cycle ergometer (metabolic); (2) after 200 drop jumps (exercise-induced muscle damage). Based on the results of these two interventions, the presence of air in the tendons after 100 drop jumps was examined further with frequently repeated ultrasound measurements.Results: Foci were detected in exercise-induced muscle damage. Twenty-three of Sixty investigated tendons (38.3%) were observed to contain hyperechoic foci after 100 drop jumps. QFT foci were present in 13/23 cases (56.5%). The location of foci in the QFT was mostly lateral and centro-lateral (76.9%). The foci disappeared completely between 40 and 180 min after completing 100 drop jumps.Conclusions: The presence of intratendinous air seems related to high-magnitude, high-force, high-strain exercise of the particular tendon areas. It might represent the stress response of tendons to overload condition