It is now generally accepted that strength training in pubertal children will increase strength, but it is unlikely to induce morphological changes. However research in this area is limited as most studies fail to control for the confounding effects of normal growth, or employ appropriate training programs. To overcome these limitations it is suggested that researchers should use a within-subject design employing an exercise regime of sufficient intensity. In adults, eccentric training has been shown to have the greatest effect on hypertrophy and strength. The purpose of the study was to examine the effects of eccentric training on muscle strength and development in children, using a one arm training model. Seventeen boys in grades 6, 7, and 8 participated in an eight week eccentric elbow flexion training program; three training sessions per week. The program consisted of 2 5 sets of 6 10 reps using progressive resistance. Pre and post test strength (Eccentric and concentric elbow flexion maximal strength by a Biodex System 3 Dynamometer and 1 RM with dumbbells) and bicep thickness measurements were performed. The change in biceps thickness was significantly greater in the training arm versus the non-training arm (7.3 +/- 8.3% vs. 0.7 +/- 7.5%) (p<0.05). No significant difference was found for isokinetic concentric strength gain between arms (p>0.05), but isokinetic eccentric strength gain in the training arm was significantly greater than the non-training arm (25.4 +/- 16.6% vs. 2.4% +/- 15.6%) (p<0.05). Training arm 1 RM isotonic strength significantly increased when compared to the non-training arm, both concentrically (35.0 +/- 15.8% vs. 14.8 +/- 13.1%) and eccentrically (45.0 +/- 16.1% vs. 21.8 +/- 8.0%) (p<0.05). Results from this study indicate eccentric strength training can increase muscle strength and hypertrophy in pubertal boys.

It is now generally accepted that strength training in pubertal children will increase strength, but it is unlikely to induce morphological changes. However research in this area is limited as most studies fail to control for the confounding effects of normal growth, or employ appropriate training programs. To overcome these limitations it is suggested that researchers should use a within-subject design employing an exercise regime of sufficient intensity. In adults, eccentric training has been shown to have the greatest effect on hypertrophy and strength. The purpose of the study was to examine the effects of eccentric training on muscle strength and development in children, using a one arm training model. Seventeen boys in grades 6, 7, and 8 participated in an eight week eccentric elbow flexion training program; three training sessions per week. The program consisted of 2 5 sets of 6 10 reps using progressive resistance. Pre and post test strength (Eccentric and concentric elbow flexion maximal strength by a Biodex System 3 Dynamometer and 1 RM with dumbbells) and bicep thickness measurements were performed. The change in biceps thickness was significantly greater in the training arm versus the non-training arm (7.3 +/- 8.3% vs. 0.7 +/- 7.5%) (p<0.05). No significant difference was found for isokinetic concentric strength gain between arms (p>0.05), but isokinetic eccentric strength gain in the training arm was significantly greater than the non-training arm (25.4 +/- 16.6% vs. 2.4% +/- 15.6%) (p<0.05). Training arm 1 RM isotonic strength significantly increased when compared to the non-training arm, both concentrically (35.0 +/- 15.8% vs. 14.8 +/- 13.1%) and eccentrically (45.0 +/- 16.1% vs. 21.8 +/- 8.0%) (p<0.05). Results from this study indicate eccentric strength training can increase muscle strength and hypertrophy in pubertal boys.

Abstract Aim: The aim of this study was to investigate how neural mechanisms operate during maximum strength training in the Quadriceps Femoris muscle group. One of the main objectives is to investigate the effects of five weeks unilateral maximum eccentric strength training on contralateral neural adaptations. The second is to investigate the effects of adding electromyographic (EMG) biofeedback into the training intervention.  Method: 20 healthy, recreationally active men and women had to undergo five weeks (three training sessions per week, resulting in 15 sessions in total) of maximum isokinetic unilateral eccentric strength training of the Quadriceps femoris muscle, with EMG biofeedback; FBG, n=10 five women and five men, or without EMG biofeedback; RTG n=10 five women and five men. The study was performed at the Laboratory of Biomechanics and Motor control, BMC Laboratory, Stockholm Sweden. Results: The results demonstrated an increase in concentric strength development in the trained leg; before 130 ± 43 Nm and after training 148 ± 46 Nm, (p=0.006). No significant increase in strength was detected for the untrained leg. Further, post hoc tests showed a tendency towards an increase in level of activation (LOA) of the trained leg in the FBG; from 69 ± 15 % before to 81 ± 13 % after training (p=0.097). No significant differences in the ecc:con EMG-ratio or in antagonist co-activation after the training intervention were shown. Conclusion: No significant difference in strength development was shown, whether training occurred with or without EMG biofeedback. However, eccentric training tended to induce transfer of neural activation to a maximum voluntary contraction (MVC) in the trained leg only in the group training with EMG biofeedback. In addition, the results revealed that eccentric strength training improved concentric strength in the trained leg but induced no transfer to the contralateral untrained leg. The benefits and prospects with incorporating feedback into training remains somewhat unknown and requires further research to obtain deeper understanding of the neural mechanisms affected by biofeedback.

Early strength increase with training is normally attributed to neural adaptations but recent evidence suggests that muscle hypertrophy occurs earlier than previously thought. The purpose of this study was to examine the time course of adaptation through 20 days of training and 5 days of detraining. Twenty-two untrained subjects trained one arm every 2nd day for 20 days. Subjects performed isokinetic eccentric biceps training at 90°/s (6 sets of 8 reps). Muscle thickness (reported in cm) via ultrasound, strength (reported in Nm) and muscle activation (electromyography) were measured before, during and after training (9 time points). Muscle thickness increased after 8 days of training (3.66±0.11 to 3.90±0.12; p<0.05) and remained above baseline until the end of training (3.97±0.12). After 5 days of detraining muscle thickness decreased (3.97±0.12 vs. 3.85±0.11; p<0.05), but remained higher than baseline (p<0.05). Muscle thickness did not change significantly in the untrained arm at any time point. Strength in the trained arm decreased after 8 days of training (65.6±4.1 to 57.5±3.5; p<0.05) and remained suppressed throughout the study. Muscle activation amplitude increased after 14 days of training (p<0.05) and remained elevated throughout the study. In conclusion, biceps muscle thickness increases very rapidly with frequent intense eccentric training although this type of training appears to impair strength. These findings provide additional evidence that muscle hypertrophy may occur much faster than has been generally accepted.

Early strength increase with training is normally attributed to neural adaptations but recent evidence suggests that muscle hypertrophy occurs earlier than previously thought. The purpose of this study was to examine the time course of adaptation through 20 days of training and 5 days of detraining. Twenty-two untrained subjects trained one arm every 2nd day for 20 days. Subjects performed isokinetic eccentric biceps training at 90°/s (6 sets of 8 reps). Muscle thickness (reported in cm) via ultrasound, strength (reported in Nm) and muscle activation (electromyography) were measured before, during and after training (9 time points). Muscle thickness increased after 8 days of training (3.66±0.11 to 3.90±0.12; p<0.05) and remained above baseline until the end of training (3.97±0.12). After 5 days of detraining muscle thickness decreased (3.97±0.12 vs. 3.85±0.11; p<0.05), but remained higher than baseline (p<0.05). Muscle thickness did not change significantly in the untrained arm at any time point. Strength in the trained arm decreased after 8 days of training (65.6±4.1 to 57.5±3.5; p<0.05) and remained suppressed throughout the study. Muscle activation amplitude increased after 14 days of training (p<0.05) and remained elevated throughout the study. In conclusion, biceps muscle thickness increases very rapidly with frequent intense eccentric training although this type of training appears to impair strength. These findings provide additional evidence that muscle hypertrophy may occur much faster than has been generally accepted.

Bakgrund: Tendinopati är en vanlig diagnos hos patienter inom primärvården, en av de vanligare formerna av tendinopati är epikondyalgi. Det är oklart vad som är den mest effektiva behandlingen för epikondyalgi. Studier har visat lovande resultat av enbart excentrisk träning (ET) samt som del av kombinationsbehandling. Det var därför relevant att kartlägga vilken effekt excentrisk träning har vid epikondyalgi. Syfte: Kartlägga och sammanställa aktuell forskning gällande evidensen för effekten av  ET på smärta och funktion vid epikondyalgi. Metod: En systematisk litteraturstudie. Litteratursökning genomfördes i databaserna PubMed, Cinahl, Web of Science samt Scopus. Åtta artiklar inkluderades. Dessa kvalitétsgranskades enligt PEDro, varefter den sammanvägda evidensen bedömdes enligt GRADE.  Resultat: De inkluderade studiernas kvalité enligt PEDro varierade från medelhög till hög. Begränsat vetenskapligt underlag för att ET inte minskar smärta vid lateral epikondyalgi (LE). Otillräckligt vetenskapligt underlag för att ET ökar funktion vid LE. Otillräckligt vetenskapligt underlag för en jämförelse av ET i olika former eller som del av kombinationsbehandling. Inga resultat för medial epikondyalgi framkom. Slutsats: ET har inte någon effekt på smärta vid LE. Det finns otillräcklig vetenskaplig grund för effekten på funktion vid LE. Interventionerna, i studierna som jämförde ET i olika former eller utvärderade kombinationsbehandlingar, skilde sig åt vilket gjorde att sammanvägningen av dessa resultat inte var möjlig. Vidare forskning behövs för att kunna fastställa effekterna av excentrisk träning vid epikondyalgi. / Background: Tendinopathy is a common diagnosis in primary care, a common form of tendinopathy is epicondylalgia. However, the most effective treatment for epicondylalgia is undetermined. Studies have shown promising results in regard to eccentric training (ET) as a stand-alone treatment as well as adjunct to other treatments. It is therefore relevant to map the effect of ET for patients with epicondylalgia. Objective: Map and compile current evidence on the effect of ET on pain and function for patients with epicondylalgia. Methods: A systematic review. A search was conducted in the PubMed, Cinahl, Web of Science and Scopus database. Eight articles were included. These were assessed for quality according to the PEDro scale and the evidence was assessed according to GRADE. Results: The quality of the included studies ranged from medium to high. Limited evidence showed that ET does not reduce pain for patients with lateral epicondylalgia, LE. Insufficient evidence showed that ET improves function. The evidence on the comparison of ET in different forms or in combination with other treatments was insufficient. No results emerged for medial epicondylalgia. Conclusion: ET does not reduce pain for patients with LE. There is insufficient evidence on the effect of ET on function for patients with LE. Studies comparing different forms of ET alone or in combination with other treatments have used different interventions, preventing the aggregation of results. Further research is needed to determine the effects of ET for patient with epicondylalgia.

Bakgrund: Excentrisk träning (ECC) har varit det dominerande träningssättet vid patellar tendinopati (PT) under de senaste 15 åren. Det skulle vara av värde för kliniker att veta vilken effekt ECC har på kort sikt efter en träningsperiod. Syfte: Systematiskt granska enskilda artiklar och bedöma tillförlitligheten i det sammanvägda resultatet gällande effekten på funktion och smärta samt förmåga att delta i sport eller fysiska aktiviteter som excentrisk träning har efter en träningsperiod på 12 veckor hos idrottande personer med PT. Design: Systematisk granskning av randomiserade kontrollerade studier. Metod: Sökningar utfördes i PubMed, CINAHL, PEDro och Cochrane library. Sju studier inkluderades och granskades med PEDro Scale. GRADEstud användes för att bedöma tillförlitligheten i resultatet. Resultat: Inkluderade studiers kvalitet varierade mellan acceptabel och hög kvalitet, enligt PEDro Scale. Det var inga skillnader mellan ECC och kontrollbehandlingar. Vid sammanvägningen av studiernas respektive resultat ansågs tillförlitligheten enligt GRADEstud vara måttligt hög (+++) p.g.a. hög samstämmighet, men bristande precision. Slutsats: ECC är inte mer effektivt än andra undersökta kontrollbehandlingar, därav kan denna studie inte säkerställa att förbättringar som sker efter 12 veckor beror på ECC. / Background: Eccentric exercise (ECC) has been the dominant treatment option for patellar tendinopathy (PT) in the last 15 years. It would be of value to clinicians to know about the short-term effect ECC has after a training period. Objective: Systematically review individual articles and assess the certainty in the weighted result regarding the effect on function, pain, and the ability to participate in sport and physical activities that eccentric training has after a 12week period of training on athletes with PT. Design: Systematic review of randomized controlled trials.                                           Method: Searches were conducted in PubMed, CINAHL, PEDro and Cochrane Library. Seven studies were included and reviewed with the PEDro Scale. GRADE-stud was used to assess the certainty in the result.  Results: Included studies quality varied between acceptable and high quality, according to the PEDro Scale. There were no differences between ECC and control treatments. When weighing the respective results of the studies, the certainty was considered moderately high (+++) according to GRADEstud, due to high coherence in all included studies, but a lack of precision. Conclusion: ECC is not more effective than other control therapies studied. Therefore, this study cannot ensure that improvements that occur after 12 weeks are due to ECC.

Bakgrund: Hälsmärta drabbar en av 10 individer någon gång i livet, i cirka 80 procent av fallen är orsaken plantar fasciit. Läkningstiden för plantar fasciit kan bli mycket lång, i vissa fall upp till två år. Följsamhet till träningsprogram är av stor betydelse för utfallet vid fysioterapeutiska behandling. Syfte: Att undersöka hur styrketräning av tårnas flexormuskulatur, med fokus på excentrisk belastning, påverkar tilltro till aktivitetsnivå (rask promenad) och symtom vid plantar fasciit. Vidare är syftet att utifrån socialkognitiv teori undersöka faktorer av betydelse för följsamhet till träning, samt hur deltagarna upplever träningen. Metod: Studien har en A-B-A Singel-Case Design. Patienter tillfrågandes löpande på en privat fysioterapimottagning. Tre deltagare inkluderades i studien. Baslinjemätningen under två veckor (A1) följdes av sex veckor intervention med avslutande baslinjemätning under två veckor (A2). Data samlades in genom självrapporterade skattningar av variabler av intresse i en träningsdagbok. Visuell avläsning har gjorts utifrån trend och lutning. Resultat: Deltagare A visade på förbättring, B och C har kvarstående eller något ökade symtom. Samtliga deltagare visade på hög self-efficacy för utförande av övningen. Deltagare A och B visade på hög följsamhet och C på lägre följsamhet till träningsprogrammet. Slutsats: Författarens slutsats är att träningsupplägget är genomförbart för patienter med plantar fasciit. För eventuell gruppstudie kunde inklusions- och exklusionskriterier föreslås baserat på resultat av denna studie. / Background: Heel pain affects 1 in 10 individuals at some point in life, in about 80% of the cases, the cause is plantar fasciitis. The healing time for plantar fasciitis can be very long, in some cases up to two years. Adherence to treatment is of great importance for the outcome in physiotherapy. Aim: To investigate how the strength of the toe flexor, focusing on the eccentric load, affecting self-efficacy for activity (power walking) and symptoms of plantar fasciitis. Further to investigate and examine factors affecting adherence to exercise, and how participants feel the workout, based of social cognitive theory. Methods: The study has an A-B-A Single-Case Design. Patients asked to participate at a private physiotherapy clinic in Sweden. Three participants were included in the study. Baseline measurements was collected for two weeks (A1) that was followed by six weeks of intervention with ending baseline measurements for two weeks (A2). Data were collected through self-reported estimates of the variables of interest in a diary. Visual reading was made based on the trend and slope. Results: Participants A showed improvement, B and C have persistent or increased symptoms. All participants showed high self-efficacy for performing the exercise. Participant A and B showed high adherence and C showed lower adherence to the exercise program. Conclusions:. The author's conclusion is that the exercise program is feasible for patients with plantar fasciitis. For a future group study the inclusion and exclusion criteria are proposed to be based on the results of this study.

Background: Training to increase muscular power is essential for improving athletic performance in most sports. Weight training (WT) is a common means for training muscular power. Another modality, flywheel resistance training (FRT), may be superior for improving muscular power. However, few studies have examined if FRT is kinematically similar to WT, or if FRT kinematics change with increasing inertial load. The purposes of this study were to determine how sagittal plane joint kinematics are affected by increasing inertial load during FRT squats, and to determine how FRT squat joint kinematics compare to WT squat joint kinematics. Methods: Subjects (n=9) completed three visits for this study. On the first visit subjects completed squat 1 repetition maximum (1RM) testing. The second visit served as a full FRT familiarization session in which subjects performed one set of 5 maximal effort FRT squats at each inertial load (0.050, 0.075, and 0.100 kgm2). On the third visit, subjects were videoed in the sagittal plane while performing the FRT squat protocol. Subjects then completed 5 maximal velocity repetitions of WT squats with the barbell loaded according to the Kansas Squat Test (KST) protocol. Kinematic differences between inertial loads were determined via 1-way repeated measures ANOVAS while differences between FRT and WT were determined with paired T-tests. Results: There were no differences in peak sagittal plane knee, trunk-hip, trunk (absolute) or ankle angles between inertial loads. Peak and mean joint angular velocities decreased with increasing inertial loads at the knee and trunk-hip. Mean joint angular velocities decreased at the ankle with increasing inertial loads, while peak and mean trunk (absolute) angular velocities were unaffected. No statistical analyses were conducted for FRT and WT comparison as not enough subjects met the criteria (n=3). Conclusions: Sagittal plane joint kinematics are largely maintained despite increasing inertial load during FRT squats. Lower extremity joint angular velocities decreased with increasing inertial load. If training for muscular power and knee extensor velocity is the goal, then the inertia of 0.050 kgm2 is most suitable.

Chronic painful tendinopathies are common, not only in sports and recreationally active people, but also among people with a sedentary lifestyle. Both the lower and upper limbs are affected. There is lack of knowledge about the etiology and pathogenesis to tendinopathy, and many different treatments options have been presented. Unfortunately, most treatments have not been tested in scientific studies. Conservative (non-surgical) treatment has since long shown unsatisfactory results and surgical treatment is known to give unpredictable results. The aim of this thesis was to evaluate new models of painful eccentric training for the conservative treatment of different chronic tendinopathies. After promising results in a pilot study, using painful eccentric calf muscle training in patients with chronic mid-portion Achilles tendinopathy, we investigated if these results could be reproduced in a larger group of patients with both mid-portion and insertional Achilles tendinopathy (study I). After 12 weeks, 89% of the patients with pain from the mid-portion were satisfied and back in previous activities. In the group with insertional Achilles tendinopathy the results were poor. A new model for eccentric training was designed for patients with insertional Achilles tendinopathy. The eccentric calf muscle training was done from tip-toe to floor level (study II). With this new regimen 67% of the patients were satisfied and back in previous activities. The next step was to investigate the effects of painful eccentric quadriceps training on patients with jumper´s knee/patellar tendinopathy (study III). Two different training protocols were used. Eccentric training performed on a 250 decline board showed promising results with reduced pain and a return to previous activities, while eccentric training without the decline board had poor results. In a following prospective study, patients with jumper´s knee/patellar tendinopathy were randomised to either concentric or eccentric painful quadriceps training on a 250 decline board (study IV). After 12 weeks of training, there were significantly better results in the group that did eccentric training. In a pilot study (study V), we investigated painful eccentric deltoideus and supraspinatus muscle training on a small group of patients on the waiting list for surgical treatment of subacromial impingement syndrome. After 12 weeks of training, 5 out of 9 patients were satisfied with the results of treatment and withdrew from the waiting list for surgery. In conclusion, the present studies showed good clinical results with low risks of side effects and low costs. Thus, we suggest that painful eccentric training should be tried in patients with Achilles and patellar tendinopathy before intratendinous injections and surgery are considered. For patients with chronic painful impingement syndrome, the results of our small pilot study are interesting, and stimulates to randomised studies on larger materials.