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The treatment of painful chronic tendinopathy is challenging. Multiple non-invasive and tendon-invasive methods are used. When traditional non-invasive treatments fail, the injections of platelet-rich plasma autologous blood or cortisone have become increasingly favored. However, there is little scientific evidence from human studies supporting injection treatment. As the last resort, intra- or peritendinous open or endoscopic surgery are employed even though these also show varying results. This ESSKA basic science committee current concepts review follows the first part on the biology, biomechanics and anatomy of tendinopathies, to provide a comprehensive overview of the latest treatment options for tendinopathy as reported in the literature.

Chronic tendinopathies represent a major problem in the clinical practice of sports orthopaedic surgeons, sports doctors and other health professionals involved in the treatment of athletes and patients that perform repetitive actions. The lack of consensus relative to the diagnostic tools and treatment modalities represents a management dilemma for these professionals. With this review, the purpose of the ESSKA Basic Science Committee is to establish guidelines for understanding, diagnosing and treating this complex pathology.

Introduction: The importance of physical activity is well investigated, but the knowledge regarding the physical activity of younger children is limited. Accelerometers have proved to be a valid method to measure physical activity in children.

Purpose: The purpose of this study was to investigate the total level of physical activity (relative to recommended level) in children in grade three at a school in northern Sweden. Furthermore, the study investigated whether there are any differences in physical activity based on gender or participation in organized sports.

Method: Forty children participated in the study. Their level of physical activity was measured using tri-accelerometry technology during one week. Each participant also completed a short questionnaire regarding their level of physical activity.

Results: No significant difference was found in the level of physical activity in relation to gender or participation in organized sports. All but one participant reached the recommended level of daily activity.

Discussion: Based on the study, children in grade three appear to be sufficiently active to achieve the daily level of activity, a positive result in spite of the alarming reports of increased sedentary behavior among children. Intensified studies are needed to see if these results recur in a broader context.

From 20 years of research on innervation patterns and pain mechanisms in chronic painful Achilles and patellar tendinopathy, we have learned that the nerves are located outside the affected tendon. With this background we use local anestetics in combination with Adrenaline when these patients are surgical treated. We have now more than 15 years of experience in treating Achilles tendinopathy, and 10 years of experience in treating patellar tendinopaty, in local anesthesia alone. I will present the scientific background and practi-cal techniques to use local anesthesia for treatment of chronic painful Achilles and patellar tendinopathy.

The chronic painful Achilles tendon mid-portion was for many years, and still is in many countries, treated with intratendinous revision surgery. However, by coincidence, painful eccentric calf muscle training was tried, and it showed very good clinical results. This finding was unexpected and led to research into the pain mechanisms involved in this condition. Today we know that there are very few nerves inside, but multiple nerves outside, the ventral side of the chronic painful Achilles tendon mid-portion. These research findings have resulted in new treatment methods targeting the regions with nerves outside the tendon, methods that allow for a rapid rehabilitation and fast return to sports.

Objectives: Surgical removal of the plantaris tendon can cure plantaris-associated Achilles tendinopathy, a condition in which Achilles and plantaris tendinopathy coexist. However, rare cases with plantaris tendinopathy alone are often misdiagnosed due to a normal Achilles tendon.

Design and setting: Prospective case series study at one centre.

Participants: Ten consecutive patients (9 men and one woman, mean age 35 years, range 19–67) with plantaris tendon-related pain alone in altogether 13 tendons were included. All had had a long duration (median 10 months, range 3 months to 10 years) of pain symptoms on the medial side of the Achilles tendon mid-portion. Preoperative ultrasound showed thickened plantaris tendon but a normal Achilles tendon.

Interventions: Operative treatment consisting of ultrasound-guided excision of the plantaris tendon.

Primary and secondary outcome measures: Scores from Victorian Institute of Sports Assessment-Achilles questionnaire (VISA-A)were taken preoperatively and postoperatively (median duration 10 months). Patient satisfaction and time until full return to sports activity level was asked by a questionnaire.

Results: The VISA-A scores increased from 61 (range 45–81) preoperatively to 97 (range 94–100) postoperatively (p<0.01). Follow-up results at 10 months (range 7–72 months) on 9/10 patients showed full satisfaction and return to their preinjury sports or recreational activity

Conclusion: The plantaris tendon should be kept in mind when evaluating painful conditions in the Achilles tendon region, especially when no Achilles tendinopathy is present. Excision of the plantaris tendon via a minor surgical procedure in local anaesthesia results in a good outcome.

Background: Non-invasive treatment is not always successful in patients with Achilles tendon disorders, and surgical treatment is instituted as the next step. There is sparse knowledge about the diagnoses, pain levels before surgery, surgically confirmed pathologies and postoperative complications in large patient groups.

Aims: To study the diagnoses, pain scores before surgery, macroscopic surgical findings and postoperative complications in a series of patients treated for Achilles disorders.

Material and methods: One surgeon operated on 771 Achilles tendons of 481 men and 290 women during a 10-year period. The clinically and ultrasound confirmed diagnoses, pre-operative pain and functional scores (Visual Analogue Scale, VAS, range 0-100; Victorian Institute Sports Tendon Assessment - Achilles questionnaire, VISA-A), macroscopic findings during surgery and postoperative complications, were retrospectively collected from a database.

Results: Clinically, by ultrasound and during surgery midportion Achilles tendinopathy was confirmed in 519 (67%) patients, 41% of them had a thickened plantaris tendon located close the Achilles tendon. Partial midportion rupture was found in 31 (4%) patients, chronic midportion rupture in 12 (2%) patients and insertional Achilles tendinopathy, including superficial and retro-calcaneal bursitis, Haglund deformity, distal Achilles tendinopathy, plantaris tendon pathology, and bone spurs, in 209 (27%) patients. The mean pre-operative pain scores for midportion Achilles tendinopathy were 73 (VAS) and 45 (VISA-A), and for insertional Achilles tendinopathy 77 (VAS) and 39 (VISA-A). For midportion Achilles tendinopathy there were 14 (3%), and for insertional Achilles tendinopathy 10 (5%), postoperative complications.

Conclusions: Patients presenting high pain scores from midportion Achilles tendinopathy were the most common. Plantaris tendon involvement is a frequent observation. For insertional Achilles tendinopathy the combination of pathology in the subcutaneous and retrocalcaneal bursa, a Haglund deformity and distal Achilles tendinopathy/tendinosis was most frequent. 

Non-contact injuries are a big part of overall injuries in floorball. Deficits in motor control due to muscle fatigue may be a factor that causes non-contact injuries. We analyzed movement changes with The Functional Movement Screen^TM (FMS) with and without muscle fatigue on women floorball players. Method: A pilot study with a cross-sectional structure. FMS test was used to measure changes in movements and to reach fatigue a 5-10 min running ramp protocol on treadmill was used. The borg RPE-scale was used to measure perceived exhaustion. Participants: Seven female floorball players playing in teams at the highest two leagues in Sweden. The participants age was 19.7 (±SD 3,2) years, length 166.4 cm (±SD 7,2) and weight 63.1 kg (±SD 4,5). Results: Through observations of the participants we noted a different movement pattern while obtaining muscle fatigue. The results of FMS total score shows no significant difference (p=0,504) before and after the VO2max running test. The FMS results from exercises that includes the lower extremities (deep squat, hurdle step, in-line lunge and straight leg raise) does not either confirm a significant difference (p=0,132). Discussion: Our subjective analyze of the movements confirms a different movement strategy with and without muscle fatigue. The non-parametric statistical analyze does not confirm this change in movements as significant. The Functional Movement Screen might not be a good tool to measure changes in movement because the movement change has to be in a specific criteria to get a lower point. Even though we saw a different movement strategy after the ramp running test, the deficit in movements was not in the specific criteria that was necessary to get a lower point. Conclusion: Through the test results and our observations we conclude that movement pattern change after an exercise that causes fatigue, does not completely show how much the movement patterns changes and what the consequences are. More research has to be done in this area to confirm such results.

Background: During the last years the fitness industry has expanded fast. Today PT is offered at almost every health club. Training with a PT have positive physical effects but it has also shown an influence on behaviour associated with training. A good relation between client and coach is needed for a positive outcome of the training.

Purpose: The aim of the study was to investigate what the clients that are training or has trained with at personal trainer during the last year consider as important factors and personal qualities related to personal trainers.

Design and method: A qualitative descriptive design was used. Data collection was done by semi-structured interviews. Data was analysed with qualitative content analysis.

Results: The analyses resulted in 3 themes, 6 categories and 17 sub categories. The themes and categories were: To appear as competent: Appearance and displayed experience ,Give a feeling of a broad knowledge.

Coaching style: To be present here and now, To personalize Pedagogical strategies: Tools to reach results, To create a secure feeling,

Conclusion: Background information of the PT should always be available at the health club or on the website. The client should have the opportunity to choose a PT based on their personal requests. This may result in good preconditions for a strong and effective working alliance. Reserach in this area are limited therefor further studies are needed. 

Background: Many women are pregnant for one or more periods of their lives. During this time, studies have shown that women tend to become physically inactive. With a pregnancy, there is also an increased risk of other diseases and disorders such as pregnancy diabetes and obesity. Studies have shown that physical activity can prevent some of these disorders. Traditionally, the general opinion on physical activity during pregnancy has been that it could be dangerous for both the pregnant woman and the fetus. Today, there is a more liberal view of physical activity during pregnancy, but research is still inadequate.Aim: Our purpose with this literature study is to examine the effects of physical activity during pregnancy in pregnancy-related disorders, and look into the current recommendations on physical activity during pregnancy.Results: Our study has seen positive effects of physical activity during pregnancy especially in pregnancy-related disorders such as lumbar pain, pelvic floor dysfunction, fatigue, gestational diabetes and weight gain, as well as some positive trends in preeclampsia, edema and pelvic girdle pain. The research on nausea and rectus diastasis is too inadequate to draw any conclusions about possible effects.Conclusion: More RCT studies on pregnancy-related disorders are needed to reach consensus about what type of physical activity, duration, intensity and frequency during pregnancy that are beneficial for these disorders. From this knowledge we can then work out more specific recommendations.

Background: Many women experience physical and psychological symptoms during their menstrual cycle. Research is scarce about how to ease subclinical menstrual disorders like dysmenorrhea, menorrhagia, premenstrual syndrome, premenstrual dysphoric syndrome, oligomenorrhea and amenorrhea without using medicines. Physical activity and diet is proved to have positive effects on several diseases and we therefore wanted to see if positive effects also could be seen on subclinical menstrual disorders.

Aim: The aim of this study was to investigate if physical activity and diet could reduce physical and psychological subclinical menstrual disorders and lead to a better wellbeing.

Method: Searching for subclinical menstrual disorders in relation to physical activity and diet in fertile, active and inactive women without the use of hormonal contraceptives was done using Pubmed.

Results: The study has shown that physical activity and diet could reduce some of the problems associated with subclinical menstrual disorders. Premenstrual syndrome (PMS) could be eased through calm, meditative activities. Positive effects could be seen when eating more often but smaller meals containing complex carbohydrates and by taking additional vitamins and minerals. Yoga has been proved to reduce menstrual pain and there’s also an indication that physical activity could improve the regularity of the menstrual cycle. Adequate energy intake is needed to avoid oligomenorrhea and amenorrhea. No clear recommendations were found for the remaining subclinical menstrual disorders.

Conclusion: The study has shown that physical activity and diet have positive effects on some subclinical menstrual disorders. Symptoms of PMS could be eased by calm, meditative activities. Yoga and physical activity have been shown to reduce dysmenorrhea. Adequate energy intake is essential to avoid oligomenorrhea and amenorrhea. Further research is needed to give general recommendations.

Little is known about injuries and risk factors in powerlifting. In other sports, training load is an important factor that influences injury risk. However, no method to quantify training load in powerlifting exist.Objectives:

The purpose of this study was to assess whether a standardised training and injury log is a feasible method to quantify training load and to prospectively record injuries.Method:The study was conducted in two phases with 7 respectively 8 powerlifters in each phase. In phase 1, the powerlifters logged their injuries and training for four weeks and then answered a feasibility questionnaire. Based on the results from the questionnaire, updates in the training and injury log were made and the powerlifters in phase 2 logged their training and injuries using the updated version and answered the same questionnaire as the powerlifters in phase 1.

Results:

It was possible to extract data and make calculations on training load based on the variables used in the training log and it was possible to calculate injury incidence and prevalence. Also, 9/12 powerlifters stated that they could use this standardised method for a period of at least 6 months.

Conclusion:

In conclusion, this standardised training and injury log seems to be a method to quantify training load and injuries in powerlifting. Further studies are needed to investigate the relationship between training load and injuries in powerlifting.

Previous research has identified strength as a key factor for performance in cross-country skiing. The purpose of the present study was to investigate the relationship between upper body strength and performance in swedish junior cross-country skiers. 33 swedish young men and 23 young women age 17,3 ± 1,0 years volunteered to participate in specific tests during a summer training camp were they completed a test battery consisting of bench press and bench pull. The strength variables obtained were correlated with FIS-points (International Ski Federation´s ranking points for distance and sprint performance) used as the performance indicator. Correlations were performed by Spearman´s rank correlation coefficient for all variables. The results showed that FIS-points for sprint correlated significantly with both bench press and bench pull. No significant correlation was found between FIS-points for distance and bench pull. These results may predict performance for cross-country skiers and indicate a justification for increased proportion of strength training. 

Effects of Menstrual Cycle and Oral Contraceptives on Sport Performance

During the menstrual cycle, there is a variation of the female steriod hormones estrogen and progestogen. These hormones has mainly reproduktive functions, but do also affect other physiological systems, which may have an influence on athletic performance. The use of oral contraceptives among female athletes matches the use among the general population. There is a concern among female athletes and there coaches weather oral contraceptives can affect the performance. The purpose of this litterature review is to determine the effect of the menstrual cycle and the use of oral contraceptives on athletic performance. Most studies indicates that neither the aerobic performance or VO₂max changes during the mestrual cycle, but an increase in ventilation during the lutheal phase has been observed. In the lutheal phase, the body temperature is elevated, which can affect the performance negatively during physical activity in hot and humid conditions. Studies evaluating the anaerobic performance shows varied results, which can be explained by few study participants, different study designs and varying definitions of menstrual cycle phase. Some studies that have examined the strength variation have not seen any difference, and others have seen an advantage during the follicular phase, when it also seems to be beneficial to train more strength training to optimize training adaptation. The use of oral contraceptives can affect the body composition of female athletes. Fat mass and BMD can increase, and is seen mainly in athleteswith mestrual dysfunctions. This can be benificial for their health and decrease the risk of injury, but may decrease performace level. The effect of oral contraceptive administration on aerobic capacity, anaerobic capacity and strength are unclear and the research has come up with varying results. Future studies should investigate oneoral contraceptive pill formulation at a time, andalso compare different formulations, to determineif that affect performance in different ways.

Key words: menstruation, oral contraceptives, female athlete, performance, hormones

BACKGROUND: Static stretching (SS) is widely used in warm-up as it is generally believed to increase mobility and reduce the risk of injury; however, SS has been shown to induce transient negative effects on subsequent muscle performance. Interestingly, recent studies have shown that sport specific exercise could restore SS-induced negative effects on certain sports, especially of explosive muscular performance. Whether sport specific exercise could restore SS-induced negative effects on isokinetic muscle performance remains unclear.

METHODS: The present study conducted two different warm-ups: 2-component warm-up and 3-component warm-up on 15 university students. Both protocols contained low intensity aerobic exercise and sport specific exercise, whereas the 3-component warm-up also contained SS which has been previously proven to induce negative effects on subsequent muscle performance. After the warm-ups, the subjects performed an isokinetic test on a Biodex. To make the sport specific exercise mimic the subsequent test, both included concentric isokinetic knee extension. During the tests, muscle performance of peak torque, mean power, and total work was recorded. Comparison of the measurements on each parameter between the two warm-ups was performed using paired t test.

RESULTS: The comparisons did not reveal any significant difference in the measurement of any parameter between the two different warm-up protocols, and calculation of Cohen's revealed small effect sizes on all of the three variables.

CONCLUSIONS: On basis of the present results and that the SS could induce transient negative effects on subsequent muscle performance, we concluded that the negative effects of the SS on the variables were restored by the isokinetic contractions.

Introduction: Iron is an essential trace mineral whose main function in the body is to produce hemoglobin, a transport molecule for oxygen and carbon dioxide. Iron deficiency is the most common nutritional deficiency in athletes and women are at particular risk of becoming iron deficient.  Objective: Examine the iron status of athletic women and the possible relation to 1) aerobic metabolism, 2) efficacy, and 3) VO2max during cycling workload  Method: Descriptive cross-sectional study. The participants mean age is 22±5,8 year, mean VO2max 43,5 ±4,6 ml/kg/min. Iron status was compared to oxygen consumption, efficacy and VO2max during a ergometer cycle test. Blood samples with analysis of the participants serum ferritin (sFer) with a cut off value of <29 ug/l were considered as low and >30 ug/l were considered as normal iron status. A submaximal and maximal ergometer cycle test was conducted on the participants. Analysis was done in form of regression analysis in JMP 13, in order to try to predict a relationship. Result: No relationship was found between the different parameters that have been compared. SFer of participants (n=48) was an average of 23±11 ug/l. SFer and VO2/l/min at 100 watts (r2=.09, P<0.05), sFer and kcal/min (r2=0.05, sFer and sFer and VO2max (r2=0.05). Conclusion: The main findings is that iron status does not have a significant relationship with aerobic metabolism, although previous research has suggested such. More participants with bigger value of ferritin and a clearer standardization around the training, diet and menstrual cycle of the women compared could have given another result.   

Football (or soccer) is a physically complex sport that involves everything from kicking, running, throwing, tackling etc. Even if most of the participants are men, more and more women are playing. As many know there are general differences between genders. A common knowledge is that men are stronger and have higher aerobic capacity. Therefore the purpose of this study was to investigate gender differences in football. 32 experienced football players participated in this study. 17 men (mean age: 22,7 ± 3,5 years, bodyweight: 79,4 ± 7,4kg) and 17 women (mean age: 22,1 ± 3,3 years, bodyweight: 65,2 ± 8,4 kg). The women play in the Swedish first division while men are playing in the Swedish third division. Subjects were tested in endurance (Yo- Yo Intermittent Endurance level 2 test), jumping ability  (Squat jump (SJ), Countermovement jump without (CMJ) and with arm swing (CMJ (a)) and sprinting ability (10 meter sprint). The result shows none significant differences between the two teams. The most differences were found in the Yo- Yo IE2 test where the men ran 2321 ± 605m in contrast to the women 1965± 505m (p=0,07).  In the sprint testes the men ran 10 meters at 1,77± 0,1s and the women 1,79± 0,1s (p=0,57). At the vertical jump testes the result where in SJ for men 33,2 ± 3,3 and women 31,2 ± 5,2 cm (p=0,11), In CMJ the men performed 35,9 ±5,2 cm and women 33,1±3,6 cm (p=0,10) and in CMJ (a) the men performed 40,0 ±7,3 cm and the women 40,0 ± 3,5 cm (p=0,98). In conclusion the men and women have a similar physical capacity since there were no significant differences found. This could be a result from different training structures or the different physical demands varying from the two divisions.

Training is preparation for what is expected to come through utilization of the plastic and resistive features of nature, known as adaptation. As such, training in humans may have a number of desired goals. These are typically related to sports performance or education. Whatever the goal, a plan needs to be made for reaching it. One needs to identify or select which activities and environments constitute the event or events to which adaptation is sought. Adaptations occurs by imposing something similar to said environment and practicing the selected activities in preparation for the events that can ultimately lead to goal fulfillment.

One quite common goal of physical training is to achieve a more lean and muscular physique, be it for reasons of performance or esthetics. A leaner and more muscular physique can have many advantages for health and quality of life. If we are to prepare the body’s physical capabilities and properties, they should be utilized in the preparation. By proper design and execution of a program for physical preparation, we set out on the path to achieve the goal.

A factor that is often highlighted as an important key to building muscle in the human body is the steroid hormone testosterone. According to the hormone hypothesis, increases in muscle mass are achieved through transient elevations in anabolic hormones, such as testosterone and IGF1, induced by physical training. To achieve hypertrophy of the muscles through physical training, one must ensure sure that the muscles get the correct signal, the growth signal, as a result of the training.

The work presented in this thesis is, in part, an examination of the hormone hypothesis, with both empirical and theoretical elements. The empirical foundations are results of an experiment in which a group of young men were subjected to a program of physical training, designed for all intents and purposes in accordance with contemporary knowledge, to result in muscular hypertrophy in the subjects. The goal was achieved, with an average 4.6% increase in lean body mass in the subjects after the training program. However, there was no evidence that anabolic hormones were elevated at any time during the measurement period.

The major part of this thesis details a model for explaining the collected observations. It is not intended to merely provide a guide for achieving a leaner more muscular physique but rather is aimed at formulating the problem of inducing the desired adaptations and difficulties involved in approaching the problem. For reasons discussed in this thesis, I do not claim that this is the full and final word on the matter. However, it goes some way toward explaining why, and perhaps how, desired goals should be formulated so that the muscles may understand them.

Introduction: Muscle sample collection can introduce variation in any measured variable due to inter- and intramuscle variation. We investigated the variation in gene expression and fiber type composition after repeated biopsy sampling from the vastus lateralis muscle. Methods: Six subjects donated 3 tissue samples each. One hour after baseline sampling from 1 vastus lateralis muscle, samples from both vastus lateralis muscles were obtained. Results: The fiber type composition differed between biopsies taken from the same leg. There were no within-subject differences in gene expression between the 3 biopsies. Multivariate analysis supports a model in which gene expression differs significantly between individuals but is not affected by repeated muscle biopsy sampling from the same subject. Conclusion: One vastus lateralis muscle sample per subject is sufficient to establish a reliable baseline for comparing gene expression representing selected pathways over time within the same individual.

The purpose of the study was to evaluate the generalisability of the heart rate-blood lactate relationship determined in laboratory testing in comparison to running over ground. This plays a crucial role to prescribe exercise intensity from laboratory results. Ten well trained runners performed a maximal oxygen uptake (VO2max) pre-test and an incremental submaximal test performed at a two degrees inclined treadmill and a running track. Statistical analysis included student’s t-test of heart rate at interpolated blood lactate levels and comparison of second order polynomial regression lines. VO2max was 60,4 ± 6 ml/kg/min for men and 56,3 ± 4,3 ml/kg/min for women. There was no significant difference in heart rate at interpolated blood lactate of 3 and 4 mmol/L. There was no significant difference between heart rate values at any running velocity. A significant difference between blood lactate values was observed 14km/h (p=0,04). When considering blood lactate values up to 6mmol/L, heart rate-blood lactate relationships were similar. In conclusion, lactate threshold testing on treadmill through incremental test protocols on a two degrees incline gives similar heart rate- blood lactate relationship as running over ground and may be used to prescribe intensity in training performed over ground. 

This study investigated the reliability of the new Onesenz on-line microdialysis lactate analyser compared to the YSI 2300 Stat Plus. Venous blood lactate concentrations were measured simultaneously with both analysers during an incremental cycle ergometer test. Eight physically active men and women completed the test to voluntary exhaustion. A total of 81 blood samples from both devices were included in the analysis. Statistical analysis was conducted through correlation, regression analysis and limits of agreement. Lactate values during graded exercise ranged from 0,5 mM/l to 14,1 mM/l. A significant correlation was observed between the two analysers, r(79)=0,98, p<0,001. Regression analysis determined the equation: [Onesenz] = 0,811*[YSI] + 0,345  and coefficient of determination (R²) was 0,95. The mean difference between the analysers was 0,15 mM/l ± 0,7 mM/l. The agreement between the two analysers deteriorated above 6 mM/l. When studying bLa values above 6 mM/l the mean difference was 1,38 ± 1,3 mM/l. In conclusion, the Onesenz lactate analyser provides reliable bLa measurements up to 6 mM/l compared to the YSI 2300. In the context of sports medicine the more time consuming method of microdialysis limits its appropriateness to longer test protocols, but on the other hand reduces human error. Still, the prototype lacks several features concerning practical usefulness.

Keywords: Blood lactate, Microdialysis, Lactate threshold, Exercise testing, Lactate analyser

The present work investigated serum vitamin D (25(OH)D) status in relation to bone and muscle qualities and functions in 19 female soccer players (13–16 years) resident at northern latitude with very low sun exposure (∼32–36 h/month) during winter season (late January to early March). Serum 25(OH)D, parathyroid hormone and bone turnover markers osteocalcin (OC) and beta carboxy-terminal collagen cross-links (β-Ctx), as well as body composition and muscle performance were examined. Hormones were tested using routine laboratory methods. Fat mass, lean mass, and bone mineral density in whole body, as well as femur and lumbar spine were evaluated with dual-energy X-ray absorptiometry. Muscle performance was assessed through isokinetic knee extension and flexion, countermovement jump, and sprint running. 25(OH)D was low (50.5 ± 12.8 nmol l−1), whereas the values of bone turnover markers were markedly high (OC: 59.4 ± 18.6 μg l−1; β-Ctx: 1075 ± 408 ng l−1). All bone and muscle measurements were normal or above normal. 25(OH) D was not significantly correlated with most of the parameters of bone and muscle quality or function, except the knee extension time to peak torque (r = −0.50, p = .03). In conclusion, the level of vitamin D is markedly low in adolescent female soccer players during the winter in Sweden. However, vitamin D levels did not significantly correlate with measures of bone and muscle except a moderate correlation in time to peak torque in the knee extensors. The practical implication of low vitamin D levels in young growing female athletes remains unclear.

Introduction: Soccer is one of the most injured sports. 70-90% of the injuries are located in the lower extremities. The most common injury is hamstring strain and accounts for 37% of lower limb damage. There is a lot of research done today on hamstring strains for male soccer players, but the injury rate for hamstring strains is not diminishing.

Purpose: This study wants to contribute to increased awareness and knowledge of the origin, rehabilitation and prevention of hamstring strains for coaches in male football teams.

Method: The study has complied already existing literature on the chosen areas to answer the purpose of the study. The chosen method on the study is a literature study.

Result: (1) Origin: High Speed Sprint & extension. (2) Rehabilitation: Individual conservative treatment. (3) Preventive measures: Eccentric exercises eg: Nordic hamstrings training, Askling Glider.

Conclusion: More knowledge is needed in the field, for both athletes and coaches, and the knowledge must be presented in a useful way.

Introduction Researchers have, for decades, contributed to an increased collective understanding of the physiological demands in cross-country skiing; however, almost all of these studies have used either non-elite subjects and/or performances that emulate cross-country skiing. To establish the physiological demands of cross-country skiing, it is important to relate the investigated physiological variables to the competitive performance of elite skiers. The overall aim of this doctoral thesis was, therefore, to investigate the external validity of physiological test variables to determine the physiological demands in competitive elite cross-country skiing.

Methods The subjects in Study I – IV were elite male (I – III) and female (III – IV) cross-country skiers. In all studies, the relationship between test variables (general and ski-specific) and competitive performances (i.e. the results from competitions or the overall ski-ranking points of the International Ski Federation (FIS) for sprint (FISsprint) and distance (FISdist) races) were analysed. Test variables reflecting the subject’s general strength, upper-body and whole-body oxygen uptake, oxygen uptake and work intensity at the lactate threshold, mean upper-body power, lean mass, and maximal double-poling speed were investigated.

Results The ability to maintain a high work rate without accumulating lactate is an indicator of distance performance, independent of sex (I, IV). Independent of sex, high oxygen uptake in whole-body and upper-body exercise was important for both sprint (II, IV) and distance (I, IV) performance. The maximal double-poling speed and 60-s double-poling mean power output were indicators of sprint (IV) and distance performance (I), respectively. Lean mass was correlated with distance performance for women (III), whereas correlations were found between lean mass and sprint performance among both male and female skiers (III). Moreover, no correlations between distance performance and test variables were derived from tests of knee-extension peak torque, vertical jumps, or double poling on a ski-ergometer with 20-s and 360-s durations (I), whereas gross efficiency while treadmill roller skiing showed no correlation with either distance or sprint performance in cross-country skiing (IV).

Conclusion The results in this thesis show that, depending on discipline and sex, maximal and peak oxygen uptake, work intensity at the lactate threshold, lean mass, double-poling mean power output, and double-poling maximal speed are all externally valid physiological test variables for evaluation of performance capability among elite cross-country skiers; however, to optimally indicate performance capability different test-variable expressions should be used; in general, the absolute expression appears to be a better indicator of competitive sprint performance whereas the influence of body mass should be considered when evaluating competitive distance performance capability of elite cross-country skiers.

The purpose was to investigate the relationship between elite females' competitive performance capability in sprint and distance cross-country skiing and the variables of gross efficiency (GE), work rate at the onset of blood-lactate accumulation (OBLA4mmol), maximal oxygen uptake (V[Combining Dot Above]O2max), maximal speed (Vmax), and peak upper-body oxygen uptake (V[Combining Dot Above]O2peak). Ten elite female cross-country skiers (age 24.5 ± 2.8 years) completed treadmill roller-skiing tests to determine GE, OBLA4mmol, and V[Combining Dot Above]O2max using the diagonal-stride technique as well as Vmax and V[Combining Dot Above]O2peak using the double-poling technique. International Ski Federations ranking points for sprint (FISsprint) and distance (FISdist) races were used as competitive performance data. There were correlations between the FISsprint and the V[Combining Dot Above]O2max expressed absolutely (p = 0.0040), Vmax (p = 0.012), and V[Combining Dot Above]O2peak expressed absolutely (p < 0.001) and as a simple ratio-standard (p = 0.049). The FISdist were correlated with OBLA4mmol (p = 0.048), V[Combining Dot Above]O2max expressed absolutely (L·min) (p = 0.015) and as a simple ratio-standard (p = 0.046), and V[Combining Dot Above]O2peak expressed absolutely (p = 0.036) and as a simple ratio-standard (ml·min·kg) (p = 0.040). The results demonstrate that the physiological abilities reflected by V[Combining Dot Above]O2max and V[Combining Dot Above]O2peak are indicators of competitive sprint and distance performance in elite female cross-country skiing. In addition, the ability to generate a high Vmax indicates the performance in sprint races, whereas the skier's OBLA4mmol reflects the performance capability in distance races. Based on the results, when evaluating the performance capacity of elite female cross-country skiers, it is recommended to use physiological variables that reflect competitive performance.

Introduction Performance in cross-country skiing is influenced by the skier’s ability to continuously produce propelling forces and force magnitude in relation to the net external forces. A surrogate indicator of the “power supply” in cross-country skiing would be a physiological variable that reflects an important performance-related capability, whereas the body mass itself is an indicator of the “power demand” experienced by the skier. To adequately evaluate an elite skier’s performance capability, it is essential to establish the optimal ratio between the physiological variable and body mass. The overall aim of this doctoral thesis was to investigate the importance of body-mass exponent optimization for the evaluation of performance capability in cross-country skiing.

Methods In total, 83 elite cross-country skiers (56 men and 27 women) volunteered to participate in the four studies. The physiological variables of maximal oxygen uptake (V̇O₂max) and oxygen uptake corresponding to a blood-lactate concentration of 4 mmol∙l^-1 (V̇O₂obla) were determined while treadmill roller skiing using the diagonal-stride technique; mean oxygen uptake (V̇O₂dp) and upper-body power output (Ẇ) were determined during double-poling tests using a ski-ergometer. Competitive performance data for elite male skiers were collected from two 15-km classical-technique skiing competitions and a 1.25-km sprint prologue; additionally, a 2-km double-poling roller-skiing time trial using the double-poling technique was used as an indicator of upper-body performance capability among elite male and female junior skiers. Power-function modelling was used to explain the race and time-trial speeds based on the physiological variables and body mass.

Results The optimal V̇O₂max-to-mass ratios to explain 15-km race speed were V̇O₂max divided by body mass raised to the 0.48 and 0.53 power, and these models explained 68% and 69% of the variance in mean skiing speed, respectively; moreover, the 95% confidence intervals (CI) for the body-mass exponents did not include either 0 or 1. For the modelling of race speed in the sprint prologue, body mass failed to contribute to the models based on V̇O₂max, V̇O₂obla, and V̇O₂dp. The upper-body power output-to-body mass ratio that optimally explained time-trial speed was Ẇ ∙ m^-0.57 and the model explained 63% of the variance in speed.

Conclusions The results in this thesis suggest that V̇O₂max divided by the square root of body mass should be used as an indicator of performance in 15-km classical-technique races among elite male skiers rather than the absolute or simple ratio-standard scaled expression. To optimally explain an elite male skier’s performance capability in sprint prologues, power-function models based on oxygen-uptake variables expressed absolutely are recommended. Moreover, to evaluate elite junior skiers’ performance capabilities in 2-km double-poling roller-skiing time trials, it is recommended that Ẇ divided by the square root of body mass should be used rather than absolute or simple ratio-standard scaled expression of power output.

The aim of this study was 1) to validate the 0.5 body-mass exponent for maximal. oxygen uptake [Formula: see text] as the optimal predictor of performance in a 15 km classical-technique skiing competition among elite male cross-country skiers and 2) to evaluate the influence of distance covered on the body-mass exponent for [Formula: see text] among elite male skiers. Twenty-four elite male skiers (age: 21.4±3.3 years [mean ± standard deviation]) completed an incremental treadmill roller-skiing test to determine their [Formula: see text]. Performance data were collected from a 15 km classical-technique cross-country skiing competition performed on a 5 km course. Power-function modeling (ie, an allometric scaling approach) was used to establish the optimal body-mass exponent for [Formula: see text] to predict the skiing performance. The optimal power-function models were found to be [Formula: see text] and [Formula: see text], which explained 69% and 81% of the variance in skiing speed, respectively. All the variables contributed to the models. Based on the validation results, it may be recommended that [Formula: see text] divided by the square root of body mass (mL · min(-1) · kg(-0.5)) should be used when elite male skiers' performance capability in 15 km classical-technique races is evaluated. Moreover, the body-mass exponent for [Formula: see text] was demonstrated to be influenced by the distance covered, indicating that heavier skiers have a more pronounced positive pacing profile (ie, race speed gradually decreasing throughout the race) compared to that of lighter skiers.

Background/Aim: Tendinopathies are pathological conditions of tissue remodelling occurring in the major tendons of the body, accompanied by excessive nociceptive signalling. Tendinopathies have been shown to exhibit an increase in the number of mast cells, which are capable of releasing histamine, tryptase and other substances upon activation, which may play a role in the development of tendinopathies. This study set out to describe the distribution patterns of a family of receptors called protease-activated receptors (PARs) within the Achilles tendon. These four receptors (PAR1, PAR2, PAR3, PAR4) are activated by proteases, including tryptase released from mast cells, and are involved in fibrosis, hyperalgesia and neovascularisation, which are changes seen in tendinopathies. Method: In order to study which structures involved in tendinopathy that these proteases can affect, biopsies from patients suffering of mid-portion Achilles tendinosis and healthy controls were collected and examined using immunohistochemistry. Tendon cells were cultured to study in vitro expression patterns. Results: The findings showed a distribution of PARs inside the tendon tissue proper, and in the paratendinous tissue, with all four being expressed on nerves and vascular structures. Double staining showed co-localisation of PARs with nociceptive fibres expressing substance P. Concerning tenocytes, PAR2, PAR3, and PAR4, were found in both biopsies of tendon tissue and cultured tendon cells. Conclusions: This study describes the expression patterns of PARs in the mid-portion of the Achilles tendon, which can help explain the tissue changes and increased pain signalling seen in tendinopathies. These findings also show that in-vitro studies of the effects of these receptors are plausible and that PARs are a possible therapeutic target in the future treatment strategies of tendinopathy.

Femoroacetabular impingement is a common injury amongst male ice hockey players. Male ice hockey players (n=35, mean age 26,8±4,1) completed an online survey regardingsymptoms, rehabilitation, return to play, pain and timing. The aim of the present study was to analyze the symptoms, rehabilitation, return to play and timing for these variables in male ice hockey players previously treated with arthroscopy for FAI. Fourtythree % of the participants had to retire due to FAI-related symptoms. The present study showed that examples of common FAI-symptoms were located in the groin area, hip flexors and lower back, and that several players were misdiagnosed before getting a FAI-diagnose. The age at onset of FAI- symptoms (mean ± SD) was 19.2±4.8. The time between arthroscopy and ice contact, and the time between arthroscopy and first game was not the deciding factor for the return to play rate. FAI causes pain for many male ice hockey players, even after postoperative rehabilitation and not all players were able to return to play after FAI-arthroscopy.When taking the whole postoperative rehabilitation into consideration, to experience pain during a greater time than not does not seem favourable for outcome regarding pain. The present study is another piece of growing evidence that FAI is a major problem amongst male ice hockey players.

The purpose of the present study was to investigate if there is a correlation between ANIMS

test and the Wingate test. We also aim to understand the metabolic demands for an ice hockey

player better. 21 male ice hockey players, age 18,0 ± 1,8 participated in the study. The study

consisted of an anaerobic bike test (Wingate test) and a repeated sprint test on ice (ANIMS

test). Participants conducted the test in a random order. Peak power, power drop,

VelocityMax were recorded for the Wingate test while time on each sprint and total sprint

time were recorded for ANIMS test. Lactate samples were taken pre-test, 0-1 minute post test

and 5 minutes post test. Results revealed that there is a significant correlation between Peak

power (Wingate test) and Time on the first sprint (ANIMS). There was also a significant

correlation between VelocityMax (Wingate test) and each of the sprints in ANIMS test. All

the sprints on ANIMS test correlated with each other. The difference in lactate concentration

from pre-test – 0-1 minute post and pre-test – 5 minutes post test was statistically significant

in both ANIMS test and Wingate test. There was no significant correlation between Peak

power (Wingate test) and Total sprint time (ANIMS). There was no significant correlation

between Power Drop on Wingate test and the increased sprint time on ANIMS test. ANIMS

test seems to be an anaerobic test since it correlates with Wingate test which is a valid

anaerobic test. High concentration of post-exercise blood lactate confirms that teams and/or

players that want to evaluate their anaerobic capacity and effect can use ANIMS test to do so.

We therefore conclude that ANIMS test can be used as a on ice anaerobic test.

There is an inadequate amount of studies which have examined Change Of Direction Speed test (CODS) and Repeated Sprint Ability test (RSA) possibility to indicate match-related physical performance, measured with GPS-system. The aim of this study was to examine the relationship between two field test, 20 meter Repeated Sprint Ability (RSA20), Modified-Change of Direction Speed test (M-CODS) and match related physical performance: average distance (MD), acceleration (ACC), deceleration (DEC), high intensity running (HL),  very high intensity running (VHL), sprints and peak velocity (MH) during games recorded with GPS system (S5, 100Hz, MinimaxX, CatapultsSports, Australia). During the pre-season, ten Swedish male elite soccer players (25.5±2.1 y/o, 78.8±3.6 kg,181.34±.9 cm), completed the two field tests. The results of the two test were later compared and related to in-game physical match performance. This study found moderate significant relationships between best time on RSA20 (RSA20_best) and acceleration added with deceleration (ACC+DEC) (r=-0.643) and sprints (r=-0.638). The conclusion of this study was that these analyzed field tests should not be used with the intention to indicate physical match related physical performance, due to the major influence of internal and external factors during gameplay.