Changes in muscle strength and morphology after muscle unloading in Special Forces missions.

The purpose of the present study was to determine the changes in maximal muscle strength, rapid force capacity, jumping performance and muscle morphology following a Special Forces military operation involving 8 days of muscle unloading. Nine male Special Forces soldiers were tested before (pre) and immediately after (post1) an 8-day simulated special support and reconnaissance (SSR) mission and after 3 h of active recovery (post2). Maximal muscle strength (MVC) and rate of force development (RFD) were measured along with maximal counter movement jump height (JH).

Acute fatigue impairs neuromuscular activity of anterior cruciate ligament-agonist muscles in female team handball players.

In sports, like team handball, fatigue has been associated with an increased risk of anterior cruciate ligament (ACL) injury. While effects of fatigue on muscle function are commonly assessed during maximal isometric voluntary contraction (MVC), such measurements may not relate to the muscle function during match play. The purpose of this study was to investigate the effect of muscle fatigue induced by a simulated handball match on neuromuscular strategy during a functional sidecutting movement, associated with the incidence of ACL injury.

Role of the nervous system in sarcopenia and muscle atrophy with aging: strength training as a countermeasure.

Aging is characterized by loss of spinal motor neurons (MNs) due to apoptosis, reduced insulin-like growth factor I signaling, elevated amounts of circulating cytokines, and increased cell oxidative stress. The age-related loss of spinal MNs is paralleled by a reduction in muscle fiber number and size (sarcopenia), resulting in impaired mechanical muscle performance that in turn leads to a reduced functional capacity during everyday tasks. Concurrently, maximum muscle strength, power, and rate of force development are decreased with aging, even in highly trained master athletes.

Recreational football training decreases risk factors for bone fractures in untrained premenopausal women.

The present intervention was designed to investigate whether a 14-week period of regular recreational association football (F) or endurance running (R) has an effect on the risk of falls and bone fractures due to gains in muscle function and volumetric bone mineral density (vBMD). Fifty healthy untrained Danish premenopausal women were randomized into two training groups (F and R) that trained 1.8+/-0.

Recreational football as a health promoting activity: a topical review.

The present review addresses the physiological demands during recreational football training and the effects on central health variables that influence the risk of life-style diseases of young and middle-aged men. Recent studies have established that recreational football, carried out as small-sided games can be characterized as having a high aerobic component with mean heart rates of 80-85% of maximum heart rate, which is similar to values observed for elite football players. In addition, the training includes multiple high-speed runs, sprints, turns, jumps and tackles, which provide a high impact on muscles and bones.

Muscle function and postural balance in lifelong trained male footballers compared with sedentary elderly men and youngsters.

The present study investigated whether elderly subjects exposed to lifelong football training have better rapid muscle force characteristics, body composition and postural stability in comparison with untrained elderly. Ten elderly men exposed to lifelong football training (FTE; 69.6 +/- 1.

High-intensity training versus traditional exercise interventions for promoting health.

Purpose: The purpose of this study was to determine the effectiveness of brief intense interval training as exercise intervention for promoting health and to evaluate potential benefits about common interventions, that is, prolonged exercise and strength training.

Methods: Thirty-six untrained men were divided into groups that completed 12 wk of intense interval running (INT; total training time 40 min wk(-1)), prolonged running (approximately 150 min wk(-1)), and strength training (approximately 150 min wk(-1)) or continued their habitual lifestyle without participation in physical training.

Results: The improvement in cardiorespiratory fitness was superior in the INT (14% +/- 2% increase in V˙O2max) compared with the other two exercise interventions (7% +/- 2% and 3% +/- 2% increases).

Fibril morphology and tendon mechanical properties in patellar tendinopathy: effects of heavy slow resistance training.

Background: Patellar tendinopathy is characterized by pathologic abnormalities. Heavy slow resistance training (HSR) is effective in the management of patellar tendinopathy, but the underlying functional mechanisms remain elusive.

Purpose: To investigate fibril morphology and mechanical properties in patellar tendinopathy and the effect of HSR on these properties.

Sensitivity analysis of pesticides contaminating groundwater by applying probability and transport methods.

The use of pesticides is a potential threat to local groundwater. Once groundwater is contaminated, it is very difficult to clean. Thus, it is of importance to assess the risk of contaminating local groundwater at an early stage when pesticides are found in soils.

Molecular aging and rejuvenation of human muscle stem cells.

Very little remains known about the regulation of human organ stem cells (in general, and during the aging process), and most previous data were collected in short-lived rodents. We examined whether stem cell aging in rodents could be extrapolated to genetically and environmentally variable humans. Our findings establish key evolutionarily conserved mechanisms of human stem cell aging.

Lower strength of the human posterior patellar tendon seems unrelated to mature collagen cross-linking and fibril morphology.

The human patellar tendon is frequently affected by tendinopathy, but the etiology of the condition is not established, although differential loading of the anterior and posterior tendon may be associated with the condition. We hypothesized that changes in fibril morphology and collagen cross-linking would parallel differences in material strength between the anterior and posterior tendon. Tendon fascicles were obtained from elective ACL surgery patients and tested micromechanically.

Early and late rate of force development: differential adaptive responses to resistance training?

The objective of this study is to investigate the potentially opposing influence of qualitative and quantitative muscular adaptations in response to high-intensity resistance training on contractile rate of force development (RFD) in the early (<100 ms) and later phases (>200 ms) of rising muscle force. Fifteen healthy young males participated in a 14-week resistance training intervention for the lower body and 10 matched subjects participated as controls. Maximal muscle strength (MVC) and RFD were measured during maximal voluntary isometric contraction of the quadriceps femoris muscle.

Corticosteroid injections, eccentric decline squat training and heavy slow resistance training in patellar tendinopathy.

A randomized-controlled single-blind trial was conducted to investigate the clinical, structural and functional effects of peritendinous corticosteroid injections (CORT), eccentric decline squat training (ECC) and heavy slow resistance training (HSR) in patellar tendinopathy. Thirty-nine male patients were randomized to CORT, ECC or HSR for 12 weeks. We assessed function and symptoms (VISA-p questionnaire), tendon pain during activity (VAS), treatment satisfaction, tendon swelling, tendon vascularization, tendon mechanical properties and collagen crosslink properties.

[Physical activity and dietary supplements].

The Danish Fitness and Nutrition Council has examined the scientific literature to evaluate the performance and health-related aspects of consuming dietary supplements in the context of physical activity. Certain nutritional supplements such as creatine and caffeine have documented ergogenic effects in specific situations. However, for the moderately physically active adult and healthy individual, who already consumes an energy- and nutrient balanced diet, consuming any currently legal dietary supplement does not seem to confer additional benefits on performance or health.

Glucosamine but not ibuprofen alters cartilage turnover in osteoarthritis patients in response to physical training.

Objective: To investigate changes in levels of serum cartilage oligomeric matrix protein (COMP) and urine c-telopeptide of type-2 collagen (CTX-II) as markers for cartilage turnover in patients with osteoarthritis (OA) of the knee, in response to muscle strength training in combination with treatment with glucosamine, ibuprofen or placebo.

Design: A 12-week double blind, placebo controlled, randomized study.

Method: Thirty-six elderly patients with bilateral tibiofemoral knee OA determined by radiography were randomly assigned to treatment with glucosamine (n=12), ibuprofen (n=12) or placebo (n=12) during 12 weeks of strength training of both legs with focus on the quadriceps muscle.

Effects of aging on human skeletal muscle after immobilization and retraining.

Inactivity is a recognized compounding factor in sarcopenia and muscle weakness in old age. However, while the negative effects of unloading on skeletal muscle in young individuals are well elucidated, only little is known about the consequence of immobilization and the regenerative capacity in elderly individuals. Thus the aim of this study was to examine the effect of aging on changes in muscle contractile properties, specific force, and muscle mass characteristics in 9 old (61-74 yr) and 11 young men (21-27 yr) after 2 wk of immobilization and 4 wk of retraining.

Glutaraldehyde cross-linking of tendon--mechanical effects at the level of the tendon fascicle and fibril.

Conclusive insight into the microscopic principles that govern the strength of tendon and related connective tissues is lacking and the importance of collagen cross-linking has not been firmly established. The combined application of whole-tissue mechanical testing and atomic force spectroscopy allowed for a detailed characterization of the effect of cross-linking in rat-tail tendon. The cross-link inducing agent glutaraldehyde augmented the tensile strength of tendon fascicles.

Identification of athletes at future risk of anterior cruciate ligament ruptures by neuromuscular screening.

Background: A high percentage of female athletes who sustain an anterior cruciate ligament (ACL) rupture suffer serious long-term consequences such as osteoarthritis and disability. Thus, identification of risk factors has high clinical relevance in the prevention of ACL rupture. Hypothesis Noninjured athletes with low knee flexor electromyography (EMG) preactivity and high knee extensor EMG preactivity during sidecutting are at increased risk of future ACL rupture.

Mechanical properties and collagen cross-linking of the patellar tendon in old and young men.

Age-related loss in muscle mass and strength impairs daily life function in the elderly. However, it remains unknown whether tendon properties also deteriorate with age. Cross-linking of collagen molecules provides structural integrity to the tendon fibrils and has been shown to change with age in animals but has never been examined in humans in vivo.

Impact of carbohydrate supplementation during endurance training on glycogen storage and performance.

Aim: Glucose ingestion may improve exercise endurance, but it apparently also influences the transcription rate of several metabolic genes and it alters muscle metabolism during an acute exercise bout. Therefore, we investigated how chronic training responses are affected by glucose ingestion.

Methods: In previously untrained males performance and various muscular adaptations were evaluated before and after 8 weeks of supervised endurance training conducted either with (n = 8; CHO group) or without (n = 7; placebo) glucose supplementation.

Changes in muscle force-length properties affect the early rise of force in vivo.

Changes in contractile rate of force development (RFD), measured within a short time interval from contraction initiation, were measured after a period of strength training that led to increases in muscle fascicle length but no measurable change in neuromuscular activity. The relationship between training-induced shifts in the moment-angle relation and changes in RFD measured to 30 ms (i.e.

Rapid muscle force capacity changes after soccer match play.

The present study examined the fatigue development in muscle mechanical properties with emphasis on rapid force characteristics and neuromuscular activity in response to high level soccer match play. Young elite soccer players (n=9) were tested before (CON) and after (POST) a soccer match for maximal knee extensor and flexor isometric strength (MVC) and contractile rate of force development (RFD) with synchronous surface electromyography (EMG) recording. Furthermore, maximal vertical jump power and related parameters were assessed.

Recreational soccer is an effective health-promoting activity for untrained men.

To examine the effects of regular participation in recreational soccer on health profile, 36 healthy untrained Danish men aged 20-43 years were randomised into a soccer group (SO; n = 13), a running group (RU; n = 12) and a control group (CO; n = 11). Training was performed for 1 h two or three times per week for 12 weeks; at an average heart rate of 82% (SEM 2%) and 82% (1%) of HR(max) for SO and RU, respectively. During the 12 week period, maximal oxygen uptake increased (p<0.

Corticosteroid administration alters the mechanical properties of isolated collagen fascicles in rat-tail tendon.

Overload tendon injuries are frequent in recreational and elite sports. The optimal treatment strategy remains unknown, but local administration of corticosteroids is one common treatment option. The direct effects of the corticosteroid administration on the tissue are not fully understood.

Muscle adaptations to plyometric vs. resistance training in untrained young men.

The purpose of this study was to compare changes in muscle strength, power, and morphology induced by conventional strength training vs. plyometric training of equal time and effort requirements. Young, untrained men performed 12 weeks of progressive conventional resistance training (CRT, n = 8) or plyometric training (PT, n = 7).