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1600-0838

Blackwell Publishing Journal Backfiles 1879-2005

Medicine

Sports Science

Chronic, painful conditions affecting tendons, frequently known as tendinopathy, are very common types of sporting injury. The tendon extracellular matrix is substantially altered in tendinopathy, and these changes are thought to precede and underlie the clinical condition. The tendon cell response to repeated minor injuries or “overuse” is thought to be a major factor in the development of tendinopathy. Changes in matrix turnover may also be effected by the cellular response to physical load, altering the balance of matrix turnover and changing the structure and composition of the tendon. Matrix turnover is relatively high in tendons exposed to high mechanical demands, such as the supraspinatus and Achilles, and this is thought to represent either a repair or tissue maintenance function. Metalloproteinases are a large family of enzymes capable of degrading all of the tendon matrix components, and these are thought to play a major role in the degradation of matrix during development, adaptation and repair. It is proposed that some metalloproteinase enzymes are required for the health of the tendon, and others may be damaging, leading to degeneration of the tissue. Further research is required to investigate how these enzyme activities are regulated in tendon and altered in tendinopathy. A profile of all the metalloproteinases expressed and active in healthy and degenerate tendon is required and may lead to the development of new drug therapies for these common and debilitating sports injuries.

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1600-0838

Blackwell Publishing Journal Backfiles 1879-2005

Medicine

Sports Science

Electronic Resource

1600-0838

Blackwell Publishing Journal Backfiles 1879-2005

Medicine

Sports Science

Electronic Resource

1600-0838

Blackwell Publishing Journal Backfiles 1879-2005

Medicine

Sports Science

Exercise in girls during growth seems to confer a high peak bone mineral density (BMD). Exercise in adulthood, in the peri- and postmenopausal period, and in old age prevents bone loss or increases BMD with a magnitude of minor biological significance. However, these changes must be regarded as beneficial compared to the age-related bone loss, which inevitably will occur if no interventions are implemented. Prospective intervention studies also suggest that exercise improves muscle strength, coordination and balance, even in elderly women, all of which are improvements with a potential of reducing the number of falls. A randomised, controlled, prospective, blinded study (the only study design that tests a hypothesis) of exercise with fracture as end point is extremely difficult to conduct, due to the large sample sizes needed. At present, no such studies exist. Retrospective and prospective observational and case–control studies suggest that physical activity in women is associated with reduced fracture risk. This may be correct, but we must never forget that a consistently replicated sampling bias may produce the same outcome.The Achilles heel of exercise is the reduction or the cessation of physical activity, which commonly occurs among middle-aged women when family and work demands reduce the time available for exercise. A higher BMD or improvement in muscle size and muscle strength achieved by exercise during adolescence seems to be eroded on retirement, leaving virtually no remaining benefits in old age, the period when fragility fractures begin to be a problem of increasing magnitude. However, recreational activities seem to maintain some of the musculo-skeletal benefits, but to date we do not know the level of activity needed to retain these benefits. Dose–response relationships need to be quantified, as also the effects on bone size, shape and architecture. Another essential question that we must address is how many fewer fractures will be the result of a community-based exercise campaign. Will efforts by the community to encourage a higher level of physical exercise, with the aim of reducing bone fractures, be cost-effective? The higher level of proof, suggesting that exercise does reduce fragility fractures and thus reduces the total cost for the society, must come from well-designed and well-executed, prospective, randomised, controlled trials. The responsibility of executing these studies lies in the hands of both researchers and the community.

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1600-0838

Blackwell Publishing Journal Backfiles 1879-2005

Medicine

Sports Science

Electronic Resource

1600-0838

Blackwell Publishing Journal Backfiles 1879-2005

Medicine

Sports Science

Electronic Resource

1600-0838

Blackwell Publishing Journal Backfiles 1879-2005

Medicine

Sports Science

The purpose of this study was to examine the outcome after surgery for an acute Achilles tendon rupture. In particular, we wanted to study whether persons who have suffered an Achilles tendon rupture are at greater risk of a contralateral tendon rupture. From September 1990 to April 1997, 168 acute Achilles tendon ruptures in 26 women and 142 men were treated operatively. In August 1998 (median: 4.2 years post injury), 154 of these patients (92%) responded to a follow-up questionnaire. Local symptoms (pain, decreased strength and/or reduced range of motion) were reported pre injury by 25% of the patients; at follow-up this had increased to 52%. Ten patients (6%) experienced a rupture on the contralateral side during the follow-up period (OR: 176 [70–282] vs. the expected rate based on the general population risk of this injury, P〈0.001). Thus, this study suggests that patients with an Achilles tendon rupture are at significantly increased risk of a contralateral tendon rupture, as well. Also, as many as half of the patients suffered from post-injury problems at long-term follow-up.

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1600-0838

Blackwell Publishing Journal Backfiles 1879-2005

Medicine

Sports Science

Exercise-induced arterial hypoxaemia is defined as a reduction in the arterial O2 pressure (PaO2) by more than 1 kPa and/or a haemoglobin O2 saturation (SaO2) below 95%. With blood gas analyses ideally reported at the actual body temperature, desaturation is a consistent finding during maximal ergometer rowing. Arterial desaturation is most pronounced at the end of a maximal exercise bout, whereas the reduction in PaO2 is established from the onset of exercise. Exercise-induced arterial hypoxaemia is multifactorial. The ability to maintain a high alveolar O2 pressure (PAO2) is critical for blood oxygenation and this appears to be difficult in large individuals. A large lung capacity and, in turn, diffusion capacity seem to protect PaO2. A widening of the PAO2–PaO2 difference does indicate that a diffusion limitation, a ventilation–perfusion mismatch and/or a shunt influence the transport of O2 from alveoli to the pulmonary capillaries. An inspired O2 fraction of 0.30 reduces the widened PAO2–PaO2 difference by 75% and prevents a reduction of PaO2 and SaO2. With a marked increase in cardiac output, diffusion limitation combined with a fast transit time dominates the O2 transport problem. Furthermore, a postexercise reduction in pulmonary diffusion capacity suggests that the alveolo-capillary membrane is affected. An antioxidant attenuates oxidative burst by neutrophilic granulocytes, but it does not affect PaO2, SaO2 or O2 uptake (VO2), and the ventilatory response to maximal exercise also remains the same. It is proposed, though, that increased concentration of certain cytokines correlates to exercise-induced hypoxaemia as cytokines stimulate mast cells and basophilic granulocytes to degranulate histamine. The basophil count increases during maximal rowing. Equally, histamine release is associated with hypoxaemia and when the release of histamine is prevented, the reduction in PaO2 is attenuated.During maximal exercise, an extreme lactate spill-over to blood allows pH decrease to below 7.1 and according to the O2 dissociation curve this is critical for SaO2. When infusion of sodium bicarbonate maintains a stable blood buffer capacity, acidosis is attenuated and SaO2 increases from 89% to 95%. This enables exercise capacity to increase, an effect also seen when O2 supplementation to inspired air restores arterial oxygenation. In that case, exercise capacity increases less than can be explained by VO2 and CaO2. Furthermore, the change in muscle oxygenation during maximal exercise is not affected when hyperoxia and sodium bicarbonate attenuate desaturation. It is proposed that other organs benefit from enhanced O2 availability, and especially the brain appears to increase its oxygenation during maximal exercise with hyperoxia.

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1600-0838

Blackwell Publishing Journal Backfiles 1879-2005

Medicine

Sports Science

Electronic Resource

1600-0838

Blackwell Publishing Journal Backfiles 1879-2005

Medicine

Sports Science

Movement is caused by force transmission from contracting muscles to bone via tendon. The collagen structure of tendon is organized in a very hierarchical manner. The collagen fibril is considered the basic force-transmitting unit of tendon, and it is embedded in a hydrophilic extracellular matrix of proteoglycans, glycoproteins and glycosaminoglycans. It has recently been shown in human peritendinous tissue is more metabolically active in response to activity than previously thought, although it remains to be established, if the level of activity influences affects fibril diameter and/or total tendon cross-sectional area. Moreover, it cannot be unequivocally concluded that tendon adaptation to physical activity is one of a quantitative and/or qualitative nature. The currently available information is almost exclusively obtained from animal data, however, techniques such as microdialysis for tendon metabolism and ultrasound combined with MRI for tendon mechanical properties has already provided information on human tendon behavior, and is likely to further add to our understanding of how tendon adapt to physical activity. This review will address the structure and function of tendon, and the current knowledge of how tendons respond to activity with respect to biomechanical properties.

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1600-0838

Blackwell Publishing Journal Backfiles 1879-2005

Medicine

Sports Science

We evaluated a short-term (3 months) and a long-term (8 months) effect of dance training on joint mobility and muscle flexibility of the spine, hip and ankle and on speed and agility in young cross-country skiers. Twenty elite cross-country skiers – aged 12–15 years – participated in the study. Five males and five females received dance training (intervention group) and five males and five females did not dance (reference group). Joint mobility and muscle flexibility of the spine, hip and ankle joints were measured using a goniometer, a kyphometer, a measuring tape and a ruler. Two sports-related functional tests – the slalom-test and the hurdle-test – were also performed. These measurements/tests were performed before the start of the dancing period and after 3 and 8 months. The subjects from the intervention group increased their speed with 0.3 s after 3 (P = 0.05) and 8 months (P = 0.02), respectively, when measured with the slalom-test. They also improved their speed and agility according to the hurdle-test after 3 months with 0.8 s (P = 0.000) and 8 months with 0.6 s (P = 0.01). Furthermore, they increased flexion–extension of the thoracic spine with 7.5° after 3 months (P = 0.05) and with 9°° after 8 months (P = 0.03) and lateral flexion of the spine with 0.04 m (P = 0.005) and 0.03 m (P = 0.02) after 3 and 8 months, respectively. The reference group was impaired or unchanged in the studied parameters after both 3 and 8 months. We conclude that dance training has a positive effect on speed and agility and on joint mobility and muscle flexibility in flexion–extension and lateral flexion of the spine in young cross-country skiers.

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1600-0838

Blackwell Publishing Journal Backfiles 1879-2005

Medicine

Sports Science

The purpose of this study was to quantify which dietary supplements augment lean mass and strength gains during resistance training. Peer-reviewed studies between the years 1967 and 2001 were included in the analysis if they met a predetermined set of experimental criteria, among which were at least 3-week duration and resistance training two or more times a week. Lean mass and strength were normalized for meta-analysis by conversion to percent change per week and by calculating the effect size for each variable. Of the 250 supplements examined, only six had more than two studies that met the criteria for inclusion in the meta-analysis. Creatine and β-hydroxy-beta-methylbutyrate (HMB) were found to significantly increase net lean mass gains of 0.36%/week and 0.28%/week and strength gains of 1.09%/week and 1.40%/week (P〈0.05), respectively. Chromium, dehydroepiandrosterone, androstenedione, and protein did not significantly affect lean gain or strength. In conclusion, two supplements, creatine and HMB, have data supporting their use to augment lean mass and strength gains with resistance training.

Electronic Resource

1600-0838

Blackwell Publishing Journal Backfiles 1879-2005

Medicine

Sports Science

The aim of this study was to investigate whether advice by health care professionals is associated with increased exercise activity in older people. As part of the Evergreen follow-up study, self-report data on exercise related advice were collected in 1996 and physical activity in 1988 and 1996 among 611 non-institutional people initially aged 65–84 years. Logistic regression analyses were used to study the association of recollection of having received exercise counseling with increased activity. Of all the subjects, 92% reported having been in contact with health care professionals during the follow-up period, and 58% of them recalled having been advised to exercise. Those men and women who recalled having received advice, started to participate in supervised exercise classes 5–6 times more often than those who did not recall being advised. The odds ratio (95% confidence interval) in men was 6.27 (1.19–32.9), and in women 5.27 (1.97–14.1). For calisthenics at home, the corresponding figure was 12.5 (3.52–44.4) in men. We concluded that initiating new physical activities in old age is strongly connected to encouragement to exercise by health care professionals. Health care professionals should be supported to promote exercise among older patients.

Electronic Resource

1600-0838

Blackwell Publishing Journal Backfiles 1879-2005

Medicine

Sports Science

The purpose of this prospective randomized intervention study was to evaluate the effect of two exercise protocols on reflex response time of vastus medialis obliquus (VMO), vastus lateralis (VL), in patients with anterior knee pain. Sixty patients were randomized into a 5-week treatment program, which consisted of only open kinetic chain tonification exercises (group I) (n = 30), or only closed kinetic chain tonification exercises (group II) (n = 30). Assessment of an aspect of neuromotor control was obtained by measuring the reflex response times of VMO and VL at the time of initial clinical examination, at the end of the exercise period (five weeks), and three months after the completion of the exercise period. At these evaluation occasions, the intensity and the number of times that the patients experienced anterior knee pain during daily life was recorded on a Visual Analog Scale (VAS). No alterations in reflex response times of VMO and VL were observed in either group. Changes of anterior knee pain over time were statistically significant in both groups. Only small and not statistically supported differences in anterior knee pain were found between the two groups. These results suggest that the reflex response times of the two vasti muscles can not be altered after a five week open or closed kinetic chain exercise program. In contrast, knee pain decreased significantly in both groups.

Electronic Resource

1600-0838

Blackwell Publishing Journal Backfiles 1879-2005

Medicine

Sports Science

To investigate the effects of simultaneous explosive-strength and endurance training on physical performance characteristics, 10 experimental (E) and eight control (C) endurance athletes trained for 9 weeks. The total training volume was kept the same in both groups, but 32% of training in E and 3% in C was replaced by explosive-type strength training. A 5-km time trial (5K), running economy (RE), maximal 20-m speed (V20 m), and 5-jump (5J) tests were measured on a track. Maximal anaerobic (MART) and aerobic treadmill running tests were used to determine maximal velocity in the MART (VMART) and maximal oxygen uptake (VO2 max). The 5K time, RE, and VMART improved (P〈0.05) in E, but no changes were observed in C. V20 m and 5J increased in E (P〈0.01) and decreased in C (P〈0.05). VO2 max increased in C (P〈0.05), but no changes were observed in E. In the pooled data, the changes in the 5K velocity during 9 weeks of training correlated (P〈0.05) with the changes in RE [O2 uptake (r=−0.54)] and VMART (r=0.55). In conclusion, the present simultaneous explosive-strength and endurance training improved the 5K time in well-trained endurance athletes without changes in their VO2 max. This improvement was due to improved neuromuscular characteristics that were transferred into improved VMART and running economy.

Electronic Resource

1600-0838

Blackwell Publishing Journal Backfiles 1879-2005

Medicine

Sports Science

A bi-directional bicycle pedal that combines proprioceptive training and evertor strengthening has been developed for the treatment of residual instability after ankle sprains. A prospective randomized study was carried out on 19 subjects with recurrent ankle sprains and positive stress X-ray films. The subjects were randomized to use either a bi-directional test pedal or a traditional uni-directional bicycle pedal and then completed a 6-week high-intensity training program on a cycle ergometer. Assessment of training intensity level was based on maximum oxygen uptake values, heart rate and lactate concentration in blood at various submaximal workloads. After completion of the training program, the subjects who had used the test pedal increased peak eversion torque at 180°°s−1 by 14.2% (P = 0.020), reduced figure-of-eight running time by 0.24 s (P = 0.003), improved single leg stance speed from 72.5% to the maximum speed of 80% (P = 0.005), and improved Karlsson functional score by 5.1 points (P = 0.005). In the control group, single leg stance improved from 56.1 to 67.8% (P = 0.018), but otherwise no significant effects were found. This study indicates that short-term high-intensity training with a bi-directional pedal improves ankle performance and may be an option in the treatment of recurrent ankle sprains.

Electronic Resource

1600-0838

Blackwell Publishing Journal Backfiles 1879-2005

Medicine

Sports Science

A prospective study of soccer injuries, involving 287 male youth players, from the ages of 12–15 was conducted in 24 Greek soccer clubs, during the course of one year. A total of 193 players sustained 209 injuries. The incidence of injuries was 4.0 injuries per 1000 h of soccer time per player, and the most common types of injuries were sprains and strains. Surprisingly, it was found that an increase of injury incidences occurred during practice. Fifty-eight injuries required medical assistance. The majority of injuries (80%) were located in the lower extremities. Collision with other players was the most common activity at the time of injury, accounting for 40% of all injuries. The conclusion of this study and the evidence from other studies suggests that youth soccer is a relatively low risk sport. However, a substantial amount of injuries could be prevented. It is necessary to identify the risk factors, which are associated with these types of injuries.

Electronic Resource

1600-0838

Blackwell Publishing Journal Backfiles 1879-2005

Medicine

Sports Science

The purpose of this study was to evaluate the events leading to acute traumatic extension deficit of the knee and the arthroscopic findings in these patients. A total of 78 consecutive patients treated in the Turku university hospital during the years 1994–1996 were included. The mean annual incidence of acute traumatic extension deficits of the knee in our study was 1.1 per 10 000 inhabitants. The single most common (33%) event causing the extension deficit was non-sports related twisting of the knee. Various sports related activities accounted for 42% of the extension deficits, and soccer was the most common sport in this group. In conclusion, acute traumatic extension deficit of the knee is usually a sign of serious intra-articular damage, and the most likely finding (in 82% of the patients in our study) is either a meniscal rupture, an anterior cruciate ligament (ACL) rupture, a patellar dislocation, or a combination of these. The lesions in these knees require prompt evaluation by an orthopaedic surgeon mainly because of the high number of bucket-handle and menisco-capsular insertion ruptures of the menisci, which are possibly suitable for repair.

Electronic Resource

1600-0838

Blackwell Publishing Journal Backfiles 1879-2005

Medicine

Sports Science

Electronic Resource

1600-0838

Blackwell Publishing Journal Backfiles 1879-2005

Medicine

Sports Science

Measurement of postural sway has several potential applications in sports medicine. Traditionally, however, rather complicated equipment has been applied. The purpose of the study was to compare two devices based on two different methods of measuring postural sway: (i) a sophisticated Kistler 9861A force platform (KIS)—which all but requires a laboratory setting—and (ii) Chattecx Balance System® (CBS)—which is particularly suited for measurement of sway in the dynamic environment of sports. Measurement of sway was performed in 29 subjects twice at baseline and twice at follow-up 2–4 weeks later. One measurement consisted of four 25-second sequences (eyes open, parallel feet; eyes closed, parallel feet; eyes open, tandem Romberg; eyes closed, tandem Romberg). Factor analysis revealed influence of sight and stance on sway, marked interaction between these two factors and a decrease in sway on retest on the same day. Coefficients of variation were—KIS: 0.13–0.23; CBS: 0.11–0.25. Body height was a covariate for all parameters. Kistler 9861A force platform and CBS were correlated (baseline: rs = 0.47; follow-up: rs = 0.9). These findings suggest that, when the effects of acclimatization and covariance of body height were taken into account, CBS was as reliable and reproducible as KIS in our laboratory.

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