There is evidence that a knee flexor exercise, the Nordic hamstring exercise (NHE), prevents hamstring injuries. The purpose of this study was therefore to develop, and to determine the reliability of, a novel NHE test device and, further, to determine the effectiveness of a 10-week low volume NHE program on NHE performance. Twenty female football (soccer) players, aged 16–30 years, participated in this study. From a kneeling position on the device, with the ankles secured under a heavy lifting sling, participants leaned forward in a controlled manner as far as possible (eccentric phase) and then returned to the starting position (concentric phase). A tape measure documented the forward distance achieved by the participants in cm. Participants completed three separate occasions to evaluate test-retest reliability. Additionally, 14 players performed a low volume (1 set of 5 repetitions) NHE program once weekly for 10 weeks. No significant test-retest differences in NHE performance were observed. The intra-class correlation coefficient was 0.95 and the coefficient of variation was 3.54% between tests. Mean improvement in the NHE performance test by the players following training was 22% (8.7 cm), p = 0.005. Our test device reliably measured NHE performance and is easy to perform in any setting. Further, NHE performance was improved by a 10-week low volume NHE program. This suggests that even a small dose (1 set of 5 repetitions once weekly) of the NHE may enhance NHE performance.

I dag används styrketräning som ett komplement i prestationshöjande syfte i stort sett inom alla idrotter. Styrketräning spelar dessutom en stor roll inom idrotten när det gäller att förebygga och rehabilitera idrottsskador. Målsättningen med denna artikel är att ge exempel på hur styrketräning kan användas i förebyggande och rehabiliterande syfte, men även hur skador kan uppstå vid styrketräning.

Styrketräning kan utövas som en egen idrott i form av tyngdlyftning och styrkelyft. Styrketräning bedrivs också i prestationshöjande syfte som ett viktigt komplement till andra träningsformer eller idrotter. Många styrketränar för att orka mer och klara vardag och fritid bättre. Sist men inte minst spelar styrketräning en viktig roll i att förebygga och behandla skador och sjukdomar.

Styrketräning är inkluderande och kan utformas så att vem som helst, oberoende av ålder och fysisk status kan utföra den. Styrketräning är också skonsam och anpassningsbar och därför alltid ett alternativ när andra träningsformer blivit för krävande och inte längre fungerar att utföra. Styrketräning är dessutom en effektiv och utmanande träningsform, på kort tid kan man pressas till total utmattning.

Det är alltså inte så konstigt att styrketräning är en av de vanligaste träningsformerna och idag har mer än två miljoner utövare i Sverige. Och i takt med att intresset för styrketräning ökar, så bidrar forskningen till att kunskapen om kropp och muskler också ökar. Denna bok är den mest heltäckande och ambitiösa om styrketräning som skrivits i Sverige och ger såväl kunskap som vägledning kring hur styrketräning ska bedrivas för att ge optimal effekt utifrån träningens syfte. Boken är indelad i olika kapitel som behandlar många olika aspekter av styrketräning. För att öka förståelsen och för att göra läsningen så stimulerande som möjligt är boken rikt illustrerad och försedd med faktarutor och sammanfattningar.

Den nya upplagan av boken har både uppdaterats och utökats med nya forskningsrön, aktuella referenser och information i samtliga kapitel. Den tillämpade delen av boken har ytterligare fördjupats med nya bilder där de mest betydelsefulla styrketräningsövningarna demonstreras på ett unikt och pedagogiskt sätt för läsaren. Kapitlen Styrketräning för unga, gravida och äldre, Förebyggande och rehabiliterande styrketräning och Kostens betydelse vid styrketräning har alla nytt innehåll. Ett helt nytt kapitel, Träningsplanering och tester för styrketräning, har tillkommit.

Styrketräning – för idrott, motion och rehabilitering riktar sig bland annat till aktiva och ledare inom idrottsrörelsen, hälso-, friskvårds-, gym- och fitnessbranschens aktörer och till utbildningar av fysioterapeuter, idrottsvetare, hälsovetare, biomedicinare, idrottslärare med flera.

Background: Overuse injuries in sports seem to be 1.5 to 2.5 times more common than traumatic injuries in the lower extremity (LE) in children and adolescents. Floorball is the most popular indoor sport in Sweden and is associated with many potential risks of injuries. However, to our knowledge, no previous studies have examined the appearance of injury in young floorball players.

Objective: The aim of the present study was to investigate the occurrence of overuse injuries in LE in floorball players aged 15 or younger, with respect to frequency, location, and consequence of injury.

Method: Fifty-seven players, from 9 different teams, participated (mean age 11±2 years). A modified version of Oslo Sports Trauma Research Center Overuse Injury Questionnaire was submitted every fourth week during five months in order to record overuse injuries in LE. An online survey software was used to send out the questionnaires.

Results: A of 42 overuse injuries in 42% (24/57) of the cohort were found. The average monthly prevalence for all players, in any anatomical area, was 28% (95% confidence total interval 18%-38%). The most common location of injuries was the knee (43%), followed by the foot (40%).

Conclusion: The present study shows, in accordance with other recent studies on children and adolescents that overuse injuries seem to be a common problem for young floorball players. Knee and foot appear to be the most common location for overuse injuries in this population. Prospective analyses of different mechanisms for overuse injury in youth athletes and the relation to growth-related overuse disorders is desirable.

Most sports science research revolves around male subjects. As a result, most of the knowledge and practices within sports are male-centric. Failing to take the biological, psychological and social (biopsychosocial) particularities of females into account is believed to hinder optimal sports participation, development and performance, with potential negative effects on the health and well-being of females. To close the knowledge gap and alleviate these issues, we aim to develop and evaluate a 12-video educational intervention that addresses female-specific subject matter: the FIDES Athlete Development Programme. The study is designed as an embedded multiple case study where at least 1320 Swedish female athletes aged 13-16 will participate, in addition to their parents and their coaches. The girls will be recruited through their sports clubs, with half being exposed to the FIDES Athlete Development Programme and the other half serving as control cases. The primary outcomes are well-being and sporting experience. To further increase our understanding of the intervention and its implications, interviews and focus group interviews with a reference group of girls and focus group interviews with a randomly selected subsample of coaches and parents will also be performed. The project is approved by the Swedish ethics committee (number: 2023-05264-01) and will be carried out in compliance with the Declaration of Helsinki. Results from the project will be published open access in peer-reviewed journals, at national and international conferences, in mass media, and a PhD thesis. The anonymised data will be made openly available in a data repository.

A high incidence of injuries has been reported in young athletes. Several factors have been associated with athletes’ sports injuries. However, scientific evidence is lacking, particularly for adolescent athletes. Hence, the Healthy Injury-Free Adolescent Athletes (HIFAA) was designed to evaluate sports injuries and examine associations with risk factors related to physical load and mental health. Secondary aims are to evaluate differences between sex, age, high school year and sports and examine injuries and the athletic situation 5 to 10 years after graduation. Adolescent athletes aged 15–19 years enrolled in high school and competing in sports to reach a national or international level of sports will be included. At inclusion, athletes will sign an informed consent form and fill out a baseline questionnaire addressing potential risk factors (eg, sports, training and competing health and injuries, and psychosocial status). Athletes will then prospectively be monitored weekly regarding injuries, physical (training/match/competing, perceived exertion) and psychological (fatigue, sleep, mental stress, recovery) load until graduation. A shortened version of the baseline questionnaire will be filled out every year, and a follow-up questionnaire regarding injuries, sporting situations and mental health will be filled out 5–10 years after graduation.

Injuries are frequent among adolescent athletes, with consequences ranging from shorter interruptions in sports performance to mental health problems and early termination of sports. A reduction of these injuries is warranted. This study will provide a detailed understanding of risk factors, a prerequisite to introducing appropriate preventive measures.

Background and Purpose: Previous studies suggest that both acute and overuse injuries seem to be quite common in middle-aged recreational padel players [1, 2]. Yet, research is limited interms of injury panorama in youth padel players. Thus, this pilot study aimed to investigate the injury prevalence of acute and overuse injuries and training load in youth padel athletes at Swedish sport high school.

Methods: 22 youth padel players (23% females) reported on weekly basis their hours of training and games and all time-loss injuries occurring during sport activity. Details on other training regimes were also recorded. Players estimated the relative impact of the overuse problems, on pain, sport participation, and performance, on a scale from 0 to 25 points for each body region which were summed in order to calculate a severity score yielding a maximum total score of 100 for each overuse problem.

Results: Total training hours was 11 (±5) h/week whereas the mean time of specific padel training was 8 (±4). All players took part in strength and conditioning training. Most (91%) players performed strength training, 50% running, 41% interval training and19% plyometric. Four players were also engaged in other sports; soccer, dancing and gymnastic. A total of 6 acute injuries were recorded; 1 ligament injury to the shoulder,1 finger sprain, 1 hamstring strain, 2 ankle sprain and 1 fracture to the foot. A total of 23 overuse problems were registered with a severity score ranging from 8 to 28.

Conclusion: The findings indicate that the training load is relatively high in youth padel athletes at Swedish sport senior high school. The results also suggest that both acute and overuse injuries are present, but that the relative impact of the overuse problems seem to be of minor extent.

Few data exist on the relationship between maximum strength and power performance, such as jumping ability in low-level female volleyball players. The aim of the present study was to determine the relationship between maximum strength and jumping performance in young female non-elite volleyball players before and after an in-season resistancetraining protocol. A 26-week, in-season resistance-training program was carried out on ten female volleyball players, aged 19 (±2). The 1 RM squat test was used to evaluate the players’ maximum strength in the lower extremities and a vertical jump (VJ) test was used to assess functional performance and power. There was a significant enhancement of 69% (p=0.005) for the squat test and 9% for the VJ test (p=0.008). A strong significant relationship was found between the VJ test and the 1 RM squat test (r=0.68, r2=0.47, p=0.0014) at the pre-test and post-test (r=0.88, r2=0.77, p=0.001). When comparing the coefficients of correlation (r=0.68 and r=0.88) between the squat tests and VJ tests, the difference that was noted was significant (p<0.001). A strong significant relationship was also noted between the 1RM squat and VJ test relative to body weight at pre-test (r=0.89, r2=0.79, p=0.001) and post-test (r=0.95, r2=0.90), p<0.001). This study demonstrates that maximum strength in squats is a major predictive factor for jumping height in young female volleyball players. Female volleyball players might therefore consider focusing on maximum strength training to improve their jumping performance.

Under covid-19-pandemin upplevde padelsporten en verklig boom i Sverige, med en dramatisk ökning av antalet nya utövare. Dock följdes denna våg av rapporter om skador relaterade till sporten, särskilt bland amatörspelare. Efter pandemin blev det en rejäl nedgång i antalet banbokningar, men framtiden för svensk padelsport ser ljus ut med en stigande popularitet hos föreningar samt en integrering i Riksidrottsförbundet. Ungdomars engagemang inom idrotten ökar och pågående forskning fokuserar på att förstå och minimera skaderisken hos padelspelare genom analys av match- och träningsbelastning samt externa riskfaktorer. 

Background The role of lower extremity (LE) muscle strength for predicting traumatic knee injury in youth athletes is largely unknown.

Aims The aim was to investigate the influence of LE muscle strength on traumatic knee injury in youth female and male athletes.

Methods 225 athletes (40% females) from sport senior high schools in Sweden were included in this case–control study. The athletes recorded any traumatic knee injury that had occurred during their high-school period in a web-based injury form. A one repetition maximum (1RM) barbell squat test was used to measure LE muscle strength. The 1RM was dichotomised to analyse ‘weak’ versus ‘strong’ athletes according to the median (weakmedian vs strongmedian).

Results 63 traumatic knee injuries, including 18 ACL injuries, were registered. The majority of injured female athletes were in the weak group compared with the strong group (p=0.0001). The odds of sustaining a traumatic knee injury and an ACL injury was 9.5 times higher and 7 times higher, respectively, in the weakmedian group compared with the strongmedian group in females (p=0.011). A relative 1RM squat <1.05kg (105% of bodyweight) was established as the best cut-off value to distinguish high versus low risk of injury in female athletes. No strength–injury relationships were observed for the male athletes (p=0.348).

Conclusions Weaker LE muscle strength predicted traumatic knee injury in youth female athletes, but not in males. This suggests that LE muscle strength should be included in injury screening in youth female athletes.

BACKGROUND: Different jump tests such as the Countermovement Jump (CMJ), Abalakov Jump (AJ) and Standing Long Jump (SLJ) are often used in practice to evaluate muscular power and functional performance in football. These tests are also used in different selection processes and talent identification, but the significance of the tests for the selection of youth players to national teams are relatively unknown. The aim of this study was to compare jump ability between youth football players selected or not selected for the national team. METHODS: In this cross-sectional study, 22 players (aged 17±2 years), 11 national players (NP) and 11 non- national players (NNP) were evaluated in three different jump tests; CMJ, AJ and SLJ. Mean scores for the tests were analysed and compared. RESULTS: Significant differences were found between the groups regarding jump height in favour of the NP group in both the CMJ (NP 39.9±5.0 cm vs NNP 34.2±4.9 cm, p=0.013) and the AJ (NP 47.1±5.4 vs NNP 40.9±4.7, p=0.010). No group difference was found regarding jump length in SLJ (NP 246.2±17.9 vs NNP 232.9±16.5, p=0.084). CONCLUSIONS: The results suggest that tests, measuring jump height, could be used as a performance indicator and part of the selection process of youth football players to national teams, whereas the use of jump length could be questioned.

KEY WORDS: Physical performance - Adolescents - Athletes

The purpose of this study was to examine the prevalence of injury and the extent of preventive actions in elite Swedish volleyball players. Injuries to players in the elite male and female Swedish division, during the 2002–2003 season, were registered by using a questionnaire. Of the 158 volleyball players (70% response rate), a total of 82 players (52%) reported 121 injuries, during a total exposure time of 24 632 h, representing an overall incidence of 0.77 injuries per player. The majority of the injuries were located in the ankle (23%), followed by the knee (18%) and the back (15%). Most injuries (62%) were classified as being of minor severity. Most injuries occurred during training (47%), and 41% of the injuries had a gradual onset. Fifty-four percent of the injuries that could be related to a specific court situation occurred during blocking, and 30% during spiking. Most players (96%) participated in injury prevention training of some kind, generally performed without supervision (58%).

Although most players took part in some kind of preventive action, one out of two players incurred an injury during the season, which indicates that the risk of suffering an injury in elite volleyball is relatively high.

The aim of this study was to evaluate the effects of a 26-weekindividualized and supervised strength and injury prevention program onperformance enhancement in young female volleyball players whocompleted resistance training with either a supervised and individualizedtraining program (experimental group, n=10) or an unsupervised nonindividualizedtraining program (control group, n=17). Exposure and injurydata were collected during the 2006-2007 season (baseline season) andthe 26-week program was conducted during the 2007-2008 season(intervention season). All players were tested for physical performance. Atpost-test, the players in the experimental group had improved significantlymore than the players in the control group for squat (p<0.0001), benchpress (p=0.048), push-ups (p=0.02) and sit-ups (p<0.0001) but not for thevertical jump test. Thirty-five percent (6/17) of the players from the controlgroup and 80% (8/10) of the players in the experimental group completedthe resistance training with compliance of no less than 50%. The presentstudy shows the importance of individualization and supervision forresistance training in young female athletes when it comes to compliance,strength gains and performance.

Background: Studies examining post-race emotional experiences in the context of endurance races among recreational athletes are scarce. The purpose of this study was to describe how recreational athletes experience the time after completing an endurance race.

Methods: In this study, a qualitative study design was used, and data collection was carried out with semi-structured interviews. The selection of subjects was completed systematically through criterion selection. The selection criteria were men and women, aged 18 years or older, who had completed an endurance race, and finished, lasting at least 180 min within the past 12 months. The interviews were analyzed using conventional qualitative content analysis.

Results: Sixteen recreational endurance athletes who, within six months, had completed an endurance race of running, cycling, cross-country skiing or Ironman, participated and were interviewed. Four overarching themes emerged from the analysis: “High on life”, “Loss of energy, Ambivalence and Melancholy”, “Activity-charged emotions”, and “Dimensions of emotions over time and new goals”, describing the content of the interviews.

Conclusions: Endurance athletes experienced varied post-race emotions that were both physically and mentally challenging, suggesting a holistic approach to managing post-race emotions would be beneficial. From the athletes’ perspectives, post-race feelings were dependent on many factors, including time spent training for a specific race, and perceived inability to set new goals for an upcoming training period. Setting future goals prior to an event may be a tool for reducing the risk of negative post-race emotions, including post-race blues.

Although push-ups and sit-ups are among the most commonly used body-weight exercises to improve and assess strength and fitness, there is a lack of reproducible test protocols in the scientific literature. The aim of this study was to evaluate the test–retest reliability of sit-ups and push-ups and to determine performance differences in muscular endurance (maximal number of repetitions) and power (timed, maximal number of repetitions in 30 s) in young women and men. Thirty-eight women and 25 men, 18–35 years of age, participated in the study. Thirteen women participants performed two test sessions of each test using a test–retest design. A high reliability was noted for both the sit-up and the push-ups tests (intraclass correlation values ranged from 0.92 to 0.95). There were no significant differences between the men and the women in the mean number of sit-ups (42 and 41 repetitions respectively for endurance and 16 and 14 repetitions respectively for power), whereas the men performed significantly more push-ups than the women (39 and 17 repetitions respectively for endurance and 29 and 13 repetitions respectively for power). In conclusion, sit-ups and push-ups are tests with high reliability, which are easy to perform and may therefore be recommended for clinical use to evaluate muscular endurance and power in young men and women. Moreover, the fact that men performed twice as many push-ups as women indicates that, when designing training programme for women, attention should be turned towards strengthening exercises of the upper body.

Background: Elbow strength ratios in relation to performance level, in male and female climbers, are scarcely documented. The aim of this study was to investigate elbow muscle strength, strength ratio and hand grip strength in climbers and its potential relationship to performance level.

Hypothesis: We hypothesized that there is a relationship between performance level and various strength variables and that greater strength is associated with higher performance level.

Study design: Cross-sectional Level of evidence 4

Methods: Forty-four men (50%) and women (mean age 27.7±6.8 years), with a mean climbing experience of 5.8±5.2 years, participated in the study. Each climber performed upper-extremity strength tests using the Isobex 3.0® and Grippit® and a questionnaire concerning data relating to climbing experience and her/his training routines.

Results: Climbing experience, in years, in relation to route level of climbing yielded an overall significant effect (p=0.043). No significant differences were found between the low, moderate and high route climbing groups when it came to time spent climbing (p > 0.05). Elbow muscle strength showed significant correlations to boulder climbing level (p < 0.05). No relationships were found between route performance level and the muscle strength tests (p > 0.05). No correlations were found between grip strength and performance level in neither the route or the boulder group.

Conclusion: The present study suggests that elbow muscle strength is an important factor for boulder performance in contrast to route climbing performance. Clinical relevance Boulder climbers might benefit from strength training whereas the values of strength gains for route climbers are not clear.

Both weak muscle strength and impaired neuromuscular control has previous been suggested as risk factors for future traumatic knee injury. However, data on the relationship between these two factors are scarce. Thus, the aim of this study was to investigate the relationship and influence of the one repetition maximum (1RM) barbell squat strength on dynamic knee valgus in elite female and male handball players. In this cross-sectional study 22 elite handball players (7 females) were included. A unilateral drop jump (VDJ) test was used for the assessment of frontal plane dynamic knee valgus. Players also performed a one repetition maximum (1RM) barbell squat test, expressed relative to bodyweight (r1RM), to assess maximal strength, which were dichotomized to analyze ‘weak’ versus ‘strong’ players according to median. Correlations were noted between r1RM in squat and knee valgus angle for both the non-dominant (r = −0.54; p = 0.009) and dominant leg (r = −0.46, p = 0.03). The odds of knee valgus were eight times higher, for the dominant leg, in the weak group compared to the strong group (p = 0.03) and 27 times higher, for the non-dominant leg (p = 0.002). The outcome of the present study suggests that maximum squat strength plays an important role when it comes to neuromuscular control of the knee, and that weak handball players are at higher risk of knee valgus compared to strong players during jumping activity.

Objectives

To compile a battery of test including various aspects of physical fitness that could be used on the field and to assess whether any of these tests are associated with future traumatic knee injuries in youth female team sports athletes.

Design

Prospective cohort.

Setting

Sport setting.

Participants

Female athletes (n = 117, age 15–19 years), from Swedish sport high schools, active in soccer, handball, or floorball.

Main outcome measures

Differences in pre-injury tests values of 11 physical fitness tests in injured versus non-injured athletes, assessed as number of traumatic knee injuries over one season.

Results

28 athletes sustained 34 traumatic knee injuries. Athletes who sustained an injury had a shorter distance on the Yo-Yo IR1 test at baseline than those without an injury (mean difference −193 m, CI -293− −65 m). None of the other tests, assessed for muscular strength, endurance, power, flexibility and dynamic knee valgus, differed between injured and non-injured athletes.

Conclusions

Youth female athletes with lower intermittent endurance capacity, assessed with the Yo-Yo IR1, seemed to be at greater risk of traumatic knee injury. Neither hop performance, flexibility, dynamic knee valgus nor isolated strength tests at baseline could distinguish between injured and non-injured youth female athletes at follow-up.

Idag erbjuds idrottsutbildning på runt 200 skolor i Sverigeför elever som vill kombinera sina gymnasiestudier medelitsatsning inom sin idrott. Aktuell forskning visar enhög prevalens av skador hos unga elitsatsande idrottaresamt att skador är en av de vanligaste orsakerna till attunga slutar med sin idrott. Medicinskt stöd på idrotts-gymnasium kan minska konsekvenserna av att varaskadad samt förebygga nya skador och det är därförmotiverat att dessa skolor har tillgång till detta stöd.

The aim of the present study was to analyse and describe muscle function, quality of life and functional capacity before and after shoulder instability surgery. Twenty-six women aged 34 (± 14) years and 95 men aged 32 (± 10) years participated in this study. All patients were on the waiting list or had undergone shoulder instability surgery. The study was performed with a cross-sectional design and patients were examined pre-operatively, 6-month post-operatively or 7-year post-operatively. Handgrip strength measurement, active range of motion (AROM), isometric shoulder muscle strength measurement, health-related quality of life measured by Western Ontario Shoulder Instability Index (WOSI©) and shoulder function using the Constant Score were evaluated. The mean AROM in flexion for women in all groups ranged from 162° (± 16) to 169° (± 12), and for men from 157° (± 19) to 162° (± 12). The mean AROM in abduction ranged from 170° (± 25) to 177°(± 5) for women and from 177° (± 8) to 179° (± 24) for men. The mean AROM in external rotation ranged from 89° (± 14) to 95° (± 14) for women and from 83° (± 21) to 85° (± 12) for men. Men were significantly stronger and had a larger AROM on the non-injured side compared with the injured side, whereas differences were found between non-injured and injured side for women only in AROM. The scores from the WOSI© for all the patients were far from normative values suggesting that the patient's subjective experience does not fully reflect the physical examination. The results from the present study can guide the physiotherapist to give patients realistic expectations of shoulder function concerning AROM and muscle strength.

Objectives: The literature is scarce in terms of injury panorama and risk factors in padel. Thus, the aims of this study were to investigate 1) injury occurrence, anatomical area and severity of acute injuries and overuse problems in women and men who regularly participate in padel; 2) relative impact of overuse problems; 3) intrinsic (age and sex) and extrinsic risk factors (equipment and environment).

Methods: Data for this observational study was collected retrospectively using an open online web-designed form. Injury data together with players’ characteristic and equipment were documented. Players also estimated the impact of the problems on a scale from 0 to 25 points for each body region which were summed in order to calculate a severity score yielding a maximum total score of 125 for each overuse problem.

Results: 274 players (38% women) reported 663 injuries (111 acute injuries and 571 overuse problems) with a higher prevalence noted in men (2.67 injuries/player) compared to women (2.01 injuries/player). Most overuse problem were located in the knee (17.5%), elbow, lower back and foot/lower leg (16% respectively). Foot, ankle and lower leg problems had the greatest impact (median severity score = 45). No associations were found between injury and age (p=0.88). More hand problems were found in women using round and soft rackets whereas men using a hard racket had more hand problems. Of the overuse problems, 33% were associated with outdoor training/games whereas only 1% with indoor.

Conclusion: The findings suggests that both acute injury and overuse problem seem to be quite common in Swedish padel player and that different racket properties are related to various kinds of overuse problems in upper extremity, which affects women and men differently. The relative high impact of foot, ankle and lower leg problems suggests that injury prevention on lower extremity are warranted. 

Trial registration: Registered on 27/10/2021. NCT05111457.

Background: Data on external stressors, such as social and environment variables and other "life events", and its relation to injury in youth athletic population are scarce. Investigating if external stressors is associated with injury risk may help coaches and other team staff to provide a more safe sport environment. The aim of the present study was to evaluate different aspects of external stressors and its potential association to traumatic knee injury in youth athletes.

Methods: This study comprised of youth female and male athletes from Swedish national sports high schools, aged 15–19 years, participating and competing in soccer, handball, or floorball. The athletes recorded any traumatic knee injury that had occurred during high-school in a web-based injury form. Data on external stressors and subjective perceived stress was also collected.

Results: The majority (60%) of stress factors noted was related to sport context. More athletes in the injured group of athletes reported life event stressor (p=0.001) and experienced stress more often (p=0.02) compared to the group of non-injured athletes. No differences between injured and non-injured athletes in terms of change of club, team coach, training protocol or game formation were noted (p>0.05). A weak correlation (r=0.20, p=0.02) was found between the number of stressors and injuries.

Conclusions: A high prevalence of external stressors are present in youth elite athletes with a majority of stress factors related to sport context. Life event stressors are present prior to injury and seem to be associated with traumatic knee injury to some degree.

Background: Studies investigating postural orientation in uninjured youth athletes are scarce. Understanding how postural orientation during functional performance tests change with age in uninjured athletes has the potential to enhance awareness of changes in performance after injury and to set realistic goals for injured athletes. Thus, the aim of this study was to explore postural orientation during functional tasks at early adolescence, and changes in postural orientation from early to middle adolescence and relate this to sex, type of sport and right leg lean body mass (RLLBM).

Methods: In this cohort study 144 (38% female) youth athletes (mean age 13.5 years, SD 0.3) were included at baseline and 86 of these at follow up 2 years later. Four functional performance tests were visually evaluated for Postural Orientation Errors (POEs) with an ordinal scale, ranging from 0 (good) to 2 (poor), yielding a maximum total POE score of 51, and RLLBM by dual energy X-ray absorptiometry.

Results: Improvements were observed in the total POE score from baseline to follow-up, median difference − 10 and − 7 (p < 0.001) for female and male athletes, respectively. At follow-up, female athletes had lower total POE score (median 18) than males (median 24) (p = 0.01). There were no differences in POE scores between sports type (team, individual, aesthetic) (p = 0.20–0.98) and no relationship between total POE score and RLLBM (rs = 0.09, p = 0.42).

Conclusions: POEs appear to be quite common in young athletic population, but improvements are achieved over time. At mid-adolescence, female athletes seem to have less POEs than males. Neither sport type nor RLLBM seem to influence postural orientation.

The aim of this study was to investigate how physical fitness performance, which is related to the strength and power of the lower extremities and core, as well as lateral agility, changes across 20 weeks of in-season training in youth female and male padel players. This study was conducted using a prospective cohort design on 16 Swedish high school padel players aged between 15 and 18 years old. The players were assessed at baseline with five tests of their physical fitness and followed prospectively, with the registration of their training load for 20 weeks, and then assessed at a follow-up, approximately five months later. The players increased their performance in all tests (p ≤ 0.02). The mean improvement in their Isometric squat test performance was 20% for peak force, 18% for relative strength value and 69% for average rate of force development. Their improvement in the squat jump test performance was 9%, whereas the improvement in their countermovement jump test was 6%. For the 30 second sit-up test, an improvement of 14% was observed. Improvements were also noted for the 30 second side hop test performance on both the right (9%) and left leg (11%). The effect size ranged from 0.31 to 1, respectively, for the tests, representing a small to large effect. The data from this study suggest that an improvement in physical fitness performance can be obtained during 20 weeks of padel training.

Background: Balance Body Tape (BBT) is a recently developed taping-method with the aim to reduce pain and improve posture through change in movement behavior. However, the potential efects of a treatment with BBT are scarcely documented. Therefore, the aim with this study was to investigate the efect of a three-week Balance body tape-treatment on the intensity of perceived neck, shoulder and back pain and forward head posture.Methods: In this RCT study, subjects (n=26), who reported being university students or having a sedentary work and experiencing pain in neck, back or shoulders, were randomized to either an intervention (n=12) or control group (n=14). The intervention group received a three-week treatment with BBT, the control group received no treatment. A questionnaire regarding pain, including a Numeric Rating Scale (NRS) measuring pain intensity, and a Photographic posture analysis measurement (PPAM) regarding the craniovertebral (CV) angle were assessed before and after the intervention for both groups. Wilcoxon’s signed rank test and Mann-Whitney U test was used to assess intra- and between group diferences respectively. The relationship between pain intensity and CV angle was assessed using Spearman’s correlation.Results: No diference in demographic and physical characteristics between the groups were noted at baseline (p>0.05). Pain intensity at baseline was 5 for the intervention group and 4 for the control group (p=0.330). At follow up, the intervention group reported a lower score (NRS=2.5, p=0.003) whereas the control group had no signifcant diference in pain intensity (NRS=3, p=0.086). No signifcant change was found in the CV angle (p=0.058) and no correlation was found between NRS and the CV angle (r=0.102, p=0.619).Conclusion: A short treatment period with BBT may, compared to no treatment, have a small reducing efect on pain intensity in neck, back and/or shoulders. However, no efect was found on forward head posture in this study.Trial registration: Registered retrospectively on 08/11/2021. NCT05111704.Trial registration page link:

AbstractBackground Studies investigating ankle condition in subjects with chronic ankle instability (CAI) using an on-thefield test battery are scarce. Understanding which tests that are most challenging for these subjects has the potentialto set realistic goals in rehabilitation and return-to-sports criteria. Thus, the primary aim of this study was to investigateCAI subjects regarding strength, balance and functional performance with an easily used test battery that requiredminimal equipment.Methods This study was conducted with a cross-sectional design. A total of 20 CAI subjects, engaged in sports,and 15 healthy subjects serving as a control group, were tested for assessment of strength, balance and functionalperformance. A test battery was developed accordingly; isometric strength in inversion and eversion, the single legstance test (SLS), single leg hop for distance (SLHD) and side hop test. The limb symmetry index was calculated todetermine whether a side-to-side lower limb difference could be classified as normal or abnormal. The sensitivity ofthe test battery was also calculated.Results The subjects were 20% weaker on the injured side compared with the non-injured side in eversion (p<0.01)and 16% weaker in inversion (p<0.01) (Table 2). For the SLS test, the mean score of the injured side was 8 points(67%) higher (more foot lifts) compared to the non-injured side (p<0.01). The mean distance of the SLHD was 10 cm(9%) shorter for the injured side compare to the non-injured side (p=0.03). The mean number of side hop was 11repetitions (29%) fewer for the injured side compare to the non-injured side (p<0.01). Six of the 20 subjects obtainedabnormal LSI values in all five tests whereas none obtained normal values in all tests. The sensitivity of the test batterywas 100%.Conclusion Deficits in muscle strength, balance and functional performance appear to be present in CAI subjectswith the largest impairments in balance and side hop performance, which stresses the need for return to sport criteriafor this group of subjects.Trial registration Registered retrospectively on 24/01/2023. NCT05732168.

Although bench press and squat are two of the most frequently performed strength training exercises today, and are used for physical performance assessment in many sports test batteries as well as in physical therapy, studies presenting inter-rater reliability for these tests in young women appear to be lacking in the literature. The aim of this study was to evaluate inter-rater reliability regarding the One Repetition Maximum (1 RM) in bench press and squats in young healthy women. Forty-one women, aged 21–30 years, participated in the present study. The subjects performed 1 RM bench press (n = 21) or 1 RM squat (n = 20) on two different occasions with an interval of 5–9 days using an inter-rater test-retest design. High reliability was noted for both the 1 RM bench press test (ICC2,1 = 0.98) and the 1 RM squat test (ICC2,1 = 0.85), with an SEM of 4% and 11%, respectively. The paired analysis revealed statistically significant difference in 1 RM squat performance between the two test sessions (p = 0.005). No statistically significant difference was found in 1 RM bench press performance between the two testing sessions. While the 1RM bench press showed excellent inter-rater reliability and could be strongly suggested as a measurement of muscle strength, the squat using free weights, as in the present study, could be questioned.

Objectives

To examine whether different vertical drop jump (VDJ) landing depth (small versus deep) and stance width (wide versus narrow) may alter movement biomechanics in female recreational athletes. The purpose was also to identify whether leg muscle strength is a predictive factor for knee control during a VDJ.

Design

Cross-sectional.

Setting

Biomechanics laboratory. Participants: Eighteen women aged between 18-30 years.

Main Outcome Measures

Three VDJ tests were used for biomechanical analysis: 1) small “bounce” jump (BJ), 2) deep “countermovement” jump with wide (CMJW) and 3) narrow foot position (CMJN). Subjects also performed an isometric knee-extension strength test, dichotomized to ‘weak’ versus ‘strong’ subjects according to median and quartiles.

Results

There were greater knee valgus angles during landing for both the CMJW and CMJN test compared to the BJ test (p≤0.05). Differences in knee valgus between weak and strong subjects were significant for the BJ test (p=0.044) but not for any of the other tests.

Conclusions

VDJ landing depth influences knee kinematics in women. Landing depth may therefore be considered when screening athletes using the VDJ test. Also, muscle strength seems to influence the amount of knee valgus angles, but the difference was not statistically significant (except for the BJ test) in this small cohort.

The aim of the present study was to explore and describe volleyball players’ experience of an individualised, supervised strength-training programme aimed at physical performance and injury prevention. The purpose was also  to use the players’ observations to obtain an understanding of the role of a physical coach. The study comprised nine  participants (age 19) who had been involved as an experimental group in a strength-training intervention study. Data  were collected using semi-structured interviews conducted by one independent interviewer. The transcribed interviews were analysed using qualitative conventional content analysis. From the analysis, three overarching themes describing the content of the text emerged: being in an enjoyable, relaxed situation, interaction between coach and athlete, mental and physical achievements. In conclusion, strength training could be used to improve self-esteem among young females. When designing strength-training intervention studies, it also seems to be important to be aware of the fear and feeling of uncertainty that could exist among the participants. From the athlete’s perspective, the performance in strength training is dependent on many factors, such as team spirit, individual goal-setting and bonding with the coach, where bonding and communication seems to be the fundamentals of coaching.

Aim: The impact of aging on muscle performance is not fully understood. The purpose was to measure muscle strength and stiffness of the calf muscle in healthy subjects of different ages. Methods: Thirty-six men between 21 and 88 years participated. Maximal voluntary contraction (MVC) and active/passive stiffness were measured with an isokinetic dynamometer. During the stiffness test the calf muscle was stimulated tetanically and when a plateau of isometric tension was obtained, a short fast stretch (200˚/s) was given.Results: MVC, active and passive stiffness declined significantly with increasing age. Age correlated well with MVC (0.78), and passive stiffness (0.63). MVC correlated with active stiffness (0.61). Active stiffness was significantly influenced by MVC and age (r2 0.36). For passive stiffness (r2 0.36) age makes the strongest contribution.Conclusion: This investigation showed that age itself contributed to passive stiffness while muscle strength was more closely related to active stiffness and the contractile components of the muscle.