Showing papers in "Scandinavian Journal of Medicine & Science in Sports in 2012"
TL;DR: The results showed that a high internal Health Locus of Control and a high self‐efficacy were useful cognitive factors to facilitate the recovery of athletes following anterior cruciate ligament injury and reconstructive surgery in athletes.
Abstract: This review describes the psychosocial factors that affect recovery following anterior cruciate ligament (ACL) injury and reconstructive surgery in athletes. A systematic search in literature with inclusion and exclusion criteria on PubMed, PsycINFO, and Embase was performed. Articles used in this review were divided in five different parts according to the biopsychosocial model of Wiese-Bjornstal, with the addition of intervention studies. The results showed that a high internal Health Locus of Control and a high self-efficacy were useful cognitive factors to facilitate the recovery. Athletes with a low level of fear of reinjury had the best knee outcome after the injury followed by a reconstruction. In addition, athletes who returned to sport had less fear of reinjury and were more experienced and established athletes compared with athletes who did not return to sport. Furthermore, researchers showed that there was a positive relation between goal setting and adherence, which in turn yielded a positive relation with the outcome of the rehabilitation of an ACL injury. There were several psychosocial interventions that appeared to be facilitating the rehabilitation process.
163 citations
TL;DR: Skiing had the highest incidence of ACL reconstructions per 100’000 person‐years, followed by Australian rules football, rugby, netball and soccer, and Males had a higher population incidence than females.
Abstract: The aim of this paper was to provide a descriptive epidemiology of anterior cruciate ligament (ACL) reconstructions in Australia. Data on all ACL reconstructions were collected from July 1, 2003 till June 30, 2008. Main outcome measures were the incidence of ACL reconstructions for Australia, per age group, sex and sport, including estimates of direct costs. There were 50 187 ACL reconstructions over the 5-year period studied. The population-based incidence of ACL reconstructions per 100 000 person-years was 52.0 [95% confidence intervals (CI): 51.6; 52.5], higher than previously published incidences from other western countries (Scandinavia 32-38). The population incidence rose rapidly through adolescence and early adulthood and then gradually declined. Males had a higher population incidence than females. Skiing had the highest incidence of ACL reconstructions per 100 000 person-years, followed by Australian rules football, rugby, netball and soccer. The total estimated hospital costs associated with ACL reconstruction surgery were over A$75 million (€45 million) per year. Further research is necessary to examine the causes for the higher population incidence of ACL reconstructions in Australia compared with other countries. The establishment of a national register of ACL injuries, similar to those developed in Scandinavia should be considered. Language: en
152 citations
TL;DR: It is concluded that high IL‐10 production in response to antigen challenge and low S‐IgA secretion are risk factors for development of URTI in physically active individuals.
Abstract: The purpose of this study was to examine factors influencing susceptibility to upper respiratory tract infections (URTI) in 18–35-year-old men and women engaged in endurance-based physical activity during the winter months Eighty individuals (46 males, 34 females) provided resting blood and saliva samples for determination of markers of systemic immunity Weekly training and illness logs were kept for the following 4 months Thirty subjects did not experience an URTI episode and 24 subjects experienced 3 or more weeks of URTI symptoms These illness-prone subjects had higher training loads and had ∼25-fold higher interleukin (IL)-4 and IL-10 production by antigen-stimulated whole blood culture than the illness-free subjects Illness-prone subjects also had significantly lower saliva S-IgA secretion rate and higher plasma IgM (but not IgA or IgG) concentration than the illness-free subjects There were no differences in circulating numbers of leukocyte subtypes or lymphocyte subsets between the illness-prone and illness-free subjects The production of IL-10 was positively correlated and the S-IgA secretion rate was negatively correlated with the number of weeks with infection symptoms It is concluded that high IL-10 production in response to antigen challenge and low S-IgA secretion are risk factors for development of URTI in physically active individuals
151 citations
TL;DR: Male gender, a high volume of volleyball training and match exposure were risk factors for developing jumper's knee, according to a multivariate analyses.
Abstract: Training volume and body composition have been suggested as risk factors for jumper’s knee among athletic youth, but research is lacking. The aim of this 4-year prospective cohort study was to examine the relationship between training and competition load, body composition, and risk for developing jumper’s knee. Participants are elite volleyball players, aged 16–18 years. Training and competition load was recorded continuously and body composition semiannually. Jumper’s knee was diagnosed on a standardized clinical examination. We recruited 141 healthy students (69 males and 72 females), and 28 developed jumper’s knee (22 boys and six girls). In a multivariate analyses, boys had three to four times higher risk compared with girls. Volleyball training had an odds ratio (OR) 1.72 (1.18–2.53) for every extra hour trained, and match exposure was the strongest sportsrelated predictor for developing jumper’s knee with an OR of 3.88 (1.80–8.40) for every extra set played per week. We did not detect any significant differences between the groups in body composition at the time of inclusion or in the change of body composition during the study period. Conclusion, male gender, a high volume of volleyball training and match exposure were risk factors for developing jumper’s knee.
146 citations
TL;DR: It is now undeniable that sedentary lifestyles are one of the most significant public health problems of the 21st century.
Abstract: Non-communicable chronic diseases (NCDs), such as cardiovascular disease, diabetes, and cancer, are currently responsible for 65% of all deaths worldwide and are projected to cause over 75% of all deaths by 2030. A substantial accumulation of epidemiological and experimental evidence has established a causal relationship between NCDs and well-known yet preventable risk factors (e.g., physical inactivity and obesity). Given that physical activity has both direct and indirect effects on the mortality and morbidity of NCDs via other risk factors (e.g., obesity, diabetes, and hypertension), it is now undeniable that sedentary lifestyles are one of the most significant public health problems of the 21st century. In 2007, the American College of Sports Medicine (ACSM) and American Medical Association (AMA) launched the Exercise is Medicine® (EIM) initiative in recognition of the fundamental importance of physical activity to health and well-being. EIM is on the forefront of a global movement to reduce sedentary lifestyles, foster implementation of exercise counseling into clinical practice, and disseminate exercise therapy on a global scale. If the devastating human losses and financial burden of inactivity-induced chronic disease are to be ameliorated, the wide-ranging cost-effective health benefits and financial feasibility of physical activity interventions must be appreciated and promoted.
127 citations
TL;DR: It is concluded that peripheral fatigue develops early during constant‐load intense cycling and is compensated by additional motor drive, while central fatigue appears to be associated with task failure.
Abstract: The kinetics of central and peripheral fatigue development during an intensive constant-load cycling exercise was evaluated to better understand the mechanisms of task failure. Thirteen males cycled to exhaustion at 80% of maximal power output in intermittent bouts of 6 min of exercise with 4-min break between bouts to assess quadriceps fatigue with maximal voluntary contractions and single (1 Hz), paired (10 and 100 Hz) potentiated and interpolated magnetic stimulations of the femoral nerve (TwQ). Surface electromyographic signals (EMG) of the quadriceps muscles were recorded during stimulations and cycling. Total cycling duration (TCD) was 27 min 38 s±7 min 48 s. The mechanical response evoked by magnetic stimulation decreased mostly during the first half of TCD (TwQ1 Hz reduction: -34.4±12.2% at 40% TCD and -44.8±9.2% at exhaustion; P<0.001), while a reduction in maximum voluntary activation was present toward the end of exercise only (-5.4±4.8% and -6.4±5.6% at 80% TCD and exhaustion, respectively; P<0.01). The increase in quadriceps EMG during cycling was significantly correlated to the TwQ reduction for the rectus femoris (r(2) =0.20 at 1 Hz, r(2) =0.47 at 100 Hz, all P≤0.001). We conclude that peripheral fatigue develops early during constant-load intense cycling and is compensated by additional motor drive, while central fatigue appears to be associated with task failure.
127 citations
TL;DR: The test battery showed good inter‐ and intra‐rater reliability and is easy to use for familiarized professionals and requires minimal equipment, however, further studies are needed to confirm the validity of the test battery in injury prevention, rehabilitation and performance enhancement.
Abstract: Studies have shown that reduced neuromuscular control or strength increases the risk of acute injuries. It is hypothesized that a non-functional movement pattern can predispose for injuries. In the present paper a detailed description of a test battery consisting of nine different tests to screen athletic movement pattern is provided. The aim was to evaluate the inter- and intra-rater reliability of the test battery on a group of male elite soccer players. Twenty-six healthy elite soccer players (17–28 years) were screened. Eighteen participated at a second occasion 7 days later. No significant difference (P 5 0.31) was found between test occasion 1 (LS means 18.3, 95% confidence interval 14.9–21.7) and test occasion 2 (18.0, 14.4–21.7) in the mean total score of the test battery. No significant difference in the inter-rater reliability was found between the eight physiotherapists at the two test occasions. The intra-class correlation coefficient was 0.80 and 0.81, respectively. The test battery showed good interand intra-rater reliability. The screening battery is easy to use for familiarized professionals and requires minimal equipment. However, further studies are needed to confirm the validity of the test battery in injury prevention, rehabilitation and performance enhancement.
126 citations
TL;DR: History of previous sprain was the strongest predictive factor and a weak performance on SEBT PL was also considered a predictive factor for ankle sprains.
Abstract: The ankle is the joint most affected among the sports-related injuries. The current study investigated whether certain intrinsic factors could predict ankle sprains in active students. The 125 participants were submitted to a baseline assessment in a single session were then followed-up for 52 weeks regarding the occurrence of sprain. The baseline assessment were performed in both ankles and included the questionnaire Cumberland ankle instability tool - Portuguese, the foot lift test, dorsiflexion range of motion, Star Excursion Balance Test (SEBT), the side recognition task, body mass index, and history of previous sprain. Two groups were used for analysis: one with those who suffered an ankle sprain and the other with those who did not suffer an ankle sprain. After Cox regression analysis, participants with history of previous sprain were twice as likely to suffer subsequent sprains [hazard ratio (HR) 2.21 and 95% confidence interval (CI) 1.07-4.57] and people with better performance on the SEBT in the postero-lateral (PL) direction were less likely to suffer a sprain (HR 0.96 and 95% CI 0.92-0.99). History of previous sprain was the strongest predictive factor and a weak performance on SEBT PL was also considered a predictive factor for ankle sprains.
126 citations
TL;DR: The longitudinal monitoring of performance and changes in stress and recovery may be useful for the detection of OR in its earliest stage and can be used to optimize individual training and recovery programs.
Abstract: The aim of this study was to prospectively monitor sport-specific performance and assess the stress-recovery balance in overreached (OR) soccer players and controls. During two competitive seasons, 94 players participated in the study. The stress-recovery balance (RESTQ-Sport) and sport-specific performance (Interval Shuttle Run Test) were assessed monthly. Seven players with performance decrement of at least a month were classified as OR. Stress and recovery measures were assessed between groups (OR vs healthy players) and at different times within the OR group. An unfavorable total recovery score appeared 2 months before diagnosis when compared with the reference values of the healthy group established at the start of the season (P=0.009) and also over the two seasons (P=0.028). The scales Emotional Stress (P=0.044), Physical Recovery (P=0.009), General Well-being (P=0.001) and Sleep Quality (P=0.045) were sensitive to OR compared with the average of the healthy group over the two seasons. Finally, Fatigue and Being in Shape demonstrated the largest changes in stress and recovery within the OR players (effect size=1.14 and 1.50). The longitudinal monitoring of performance and changes in stress and recovery may be useful for the detection of OR in its earliest stage. The information obtained from these tests can be used to optimize individual training and recovery programs.
125 citations
TL;DR: About 1/3 of the World Cup alpine, freestyle and snowboard athletes sustain a time‐loss injury each season, while the risk is low in the Nordic disciplines.
Abstract: There is little information available on injuries to World Cup skiers and snowboarders. The aim of this study was to describe and compare the injury risk to World Cup athletes in alpine skiing, freestyle skiing, snowboarding, ski jumping, Nordic combined and cross country skiing. We performed retrospective interviews with the International Ski Federation (FIS) World Cup athletes from selected nations during the 2006-2007 and 2007-2008 winter seasons and recorded all acute injuries occurring during the seasons. We interviewed 2121 athletes and recorded 705 injuries. There were 520 (72%) time-loss injuries and 196 (28%) severe injuries (absence >28 days). In freestyle skiing, alpine skiing and snowboarding, there were 27.6, 29.8 and 37.8 time-loss and 14.4, 11.3 and 13.8 severe injuries per 100 athletes per season, respectively. In Nordic combined, ski jumping and cross country skiing, there were 15.8, 13.6 and 6.3 time-loss and 3.3, 5.6 and 0.7 severe injuries per 100 athletes per season, respectively. In conclusion about 1/3 of the World Cup alpine, freestyle and snowboard athletes sustain a time-loss injury each season, while the risk is low in the Nordic disciplines. A particular concern was the high proportion of severe injuries observed among alpine, freestyle and snowboard athletes, which is in contrast to most other sports.
122 citations
TL;DR: Results showed that HIE increased anti‐inflammatory cytokine expression and CD4+CD25+ Treg cell proportion and decreased IFN‐γ expression, T‐lymphocyte proliferation, and antigen‐specic cytotoxic response in HBV DNA vaccine‐immunized mice, indicating lower the risk of cancer and infectious illness through enhancing the pro‐inflammatory responses.
Abstract: To understand the underlying mechanism(s) for the effect of exercise at different intensities on T cell and DNA vaccination responses, we treated mice in a training protocol with regular moderate-intensity exercise (MIE) or prolonged, exhaustive high-intensity exercise (HIE). After 6 weeks of training, splenocytes were isolated to evaluate cytokine expression and T-regulatory (Treg) cell proportion by RTPCR and FACS, respectively. Another set of mice that completed the same training protocol were used to determine DNA vaccination responses. These mice were immunized three times with HBV DNA vaccine at 2-week intervals and euthanized on day 14 after the last immunization. Serum and splenocytes were isolated to determine humoral and cell-mediated immunity (CMI). Results showed that HIE increased anti-inflammatory cytokine expression and CD4 1 CD25 1 Treg cell proportion. Further, HIE decreased IFN-c expression, T-lymphocyte proliferation, and antigen-specic cytotoxic response in HBV DNA vaccine-immunized mice. MIE did not change anti-inflammatory cytokine expression or CD4 1 CD25 1 Treg cell proportion but increased pro-inflammatory cytokine expression and augmented antigen-specific CMI. Thus, MIE lower the risk of cancer and infectious illness through enhancing the pro-inflammatory responses. By contrast, HIE might increase the risk of common infections, such as upper respiratory tract infection, due to an upregulation of CD4 1 CD25 1 Treg cells and anti-inflammatory responses.
TL;DR: WBV embedded in a multipurpose exercise program showed minor additive effects on body composition and neuromuscular performance, but concerning muscle strength and power, there was a tendency in favor of the VTG.
Abstract: We examined whether the effect of multipurpose exercise can be enhanced by whole-body vibration (WBV). One hundred and fifty-one post-menopausal women (68.5 ± 3.1 years) were randomly assigned to three groups: (1) a training group (TG); (2) training including vibration (VTG); and (3) a wellness control group (CG). TG and VTG performed the same training program twice weekly (60 min), consisting of aerobic and strength exercises, with the only difference that leg strength exercises (15 min) were performed with (VTG) or without (TG) vibration. CG performed a low-intensity "wellness" program. At baseline and after 18 months, body composition was determined using dual-X-ray-absorptiometry. Maximum isometric strength was determined for the legs and the trunk region. Leg power was measured by countermovement jumps using a force-measuring plate. In the TG lean body mass, total body fat, and abdominal fat were favorably affected, but no additive effects were generated by the vibration stimulus. However, concerning muscle strength and power, there was a tendency in favor of the VTG. Only vibration training resulted in a significant increase of leg and trunk flexion strength compared with CG. In summary, WBV embedded in a multipurpose exercise program showed minor additive effects on body composition and neuromuscular performance.
TL;DR: From a functional point of view the reflex reduction may serve to suppress uncontrollable reflex mediated joint oscillations and improve postural control going along with slackline training.
Abstract: "Slacklining" represents a modern sports activity where people have to keep balance on a tightened ribbon. The first trials on the slackline result in uncontrollable lateral swing of the supporting leg. Training decreases those oscillations and therefore improves postural control. However, the underlying neural mechanisms are not known. Therefore, the present study aimed to highlight spinal adaptations going along with slackline training. Twenty-four subjects were either assigned to a training or a control group and postural control was assessed before and after the 10 training sessions. Additionally, soleus Hoffmann (H)-reflexes were elicited to evaluate changes in the excitability of the spinal reflex circuitry. Trained subjects were able to maintain balance on the slackline for at least 20 s (P<0.001) and reduced platform movements on the balance board (P<0.05). The H-reflexes were significantly diminished (P<0.05) while no changes occurred in the background electromyography (bEMG). The control group showed no significant changes. From a functional point of view the reflex reduction may serve to suppress uncontrollable reflex mediated joint oscillations. As the bEMG remained unchanged, presynaptic rather than post-synaptic mechanisms are speculated to be responsible for the changes in the Ia-afferent transmission.
TL;DR: Although MVPAPE was low, PE played a considerable role in providing PA and was not compensated by reducing extracurricular MVPA.
Abstract: For many children, physical activity (PA) during physical education (PE) lessons provides an important opportunity for being physically active. Although PA during PE has been shown to be low, little is known about the contribution of PA during PE to overall PA. The aim was therefore to assess children's PA during PE and to determine the contribution of PE to overall PA with special focus on overweight children. Accelerometer measurements were done in 676 children (9.3 ± 2.1 years) over 4-7 days in 59 randomly selected classes. Moderate-and-vigorous PA (MVPA; ≥ 2000 counts/min) during PE (MVPAPE ), overall MVPA per day (MVPADAY ), and a comparison of days with and without PE were calculated by a regression model with gender, grade, and weight status (normal vs overweight) as fixed factors and class as a random factor. Children spent 32.8 ± 15.1% of PE time in MVPA. Weight status was not associated to MVPAPE . MVPAPE accounted for 16.8 ± 8.5% of MVPADAY , and 17.5 ± 8.2% in overweight children. All children were more active on days with PE than on days without PE (differences: 16.1 ± 29.0 min of MVPADAY ; P ≤ 0.001; 13.7 ± 28.0 min for overweight children). Although MVPAPE was low, PE played a considerable role in providing PA and was not compensated by reducing extracurricular MVPA.
TL;DR: Sedentary women felt relatively positive in the self‐selected condition but would benefit from familiarization and experience with exercise to enhance their self‐efficacy and competence.
Abstract: The purpose of the study was to compare affective and motivational responses to exercise performed at self-selected and prescribed intensity [close to ventilatory threshold (VT)] between physically active and sedentary women. Following a graded exercise test, the women completed two 30 min bouts of treadmill exercise (on separate days, order counterbalanced). Intensity was prescribed in one session and self-selected in the other. Exercise intensity, exercise-efficacy, perceived competence, autonomy and affective responses were assessed. Results showed that the active women self-selected to exercise at a significantly higher %HR(peak) than their sedentary counterparts but, importantly, both groups exercised close to their VT. The order of conditions influenced affective and motivational responses. The active women experienced more positive affect during exercise and greater competence than sedentary women when the self-selected condition was completed first. Autonomy was higher for the self-selected condition. Self-efficacy and competence were higher in the active women. Differences in self-efficacy perceptions before the exercise depended on which condition was completed first. In conclusion, sedentary women felt relatively positive in the self-selected condition but would benefit from familiarization and experience with exercise to enhance their self-efficacy and competence.
TL;DR: In conclusion, local IGF‐I administration can directly enhance tendon collagen synthesis both within and around the human tendon tissue.
Abstract: patellar tendon were performed 24-h apart, respectively. Tendon collagen fractional synthesis rate (FSR) was measured by stable isotope technique in the hours after the second injection. Simultaneously, interstitial peritendinous (IGF-I) and [procollagen type I N-terminal propeptide (PINP)], as a marker for type I collagen synthesis, were determined by microdialysis technique. Tendon collagen FSR and PINP were significantly higher in the IGF-I leg compared with the control leg (P < 0.05). In conclusion, local IGF-I administration can directly enhance tendon collagen synthesis both within and around the human tendon tissue.
TL;DR: In this paper, the authors examined the risk factors and prognostic indicators for medial tibial stress syndrome (MTSS) and found that increased ankle plantar flexion and positive navicular drop were associated with a longer duration to full recovery.
Abstract: The objective of the study was to examine the risk factors and prognostic indicators for medial tibial stress syndrome (MTSS). In total, 35 subjects were included in the study. For the risk factor analysis, the following parameters were investigated: hip internal and external ranges of motion, knee flexion and extension, dorsal and plantar ankle flexion, hallux flexion and extension, subtalar eversion and inversion, maximal calf girth, lean calf girth, standing foot angle and navicular drop test. After multivariate regression decreased hip internal range of motion, increased ankle plantar flexion and positive navicular drop were associated with MTSS. A higher body mass index was associated with a longer duration to full recovery. For other prognostic indicators, no relationship was found.
TL;DR: It was concluded that age appeared to moderate the impact of social influence from significant others on young athletes' sport experiences.
Abstract: The purposes of this study were to assess the relative impact of social influences initiated by coach, parents, and peers on children and adolescent athletes' motivational patterns, involving self-rated effort, enjoyment, competence, and competitive trait anxiety. Questionnaire data were collected from 408 youth swimmers (aged 9-18 years). Results of multi-group structural equation modeling analyses generally showed that compared with athletes in the other age group, the social influence from mother was stronger in childhood (mean age=10.87 years; SD=1.00), and that from peers was greater in adolescence (mean age=16.32 years; SD=1.15). The social influence from coach was more influential for athletes' effort and enjoyment in childhood, and competence in adolescence. We concluded that age appeared to moderate the impact of social influence from significant others on young athletes' sport experiences.
TL;DR: Data indicate that ET adaptations might be detected in each individual using multiple variables of different adaptation levels and intensity domains, and nonresponse seems to occur frequently and might affect all variables.
Abstract: Lacking responses to endurance training (ET) have been observed for several variables. However, detailed analyses of individuals' responses are scarce. To learn more about the variability of ET adaptations, patterns of response were analyzed for each subject in a 1-year ET study. Eighteen participants [42 ± 5 years, body mass index: 24 ± 3 kg/m(2), maximal oxygen uptake (VO(2max) ): 38 ± 5 mL/min/kg] completed a 1-year jogging/walking program on 3 days/week, 45 min/session at 60% heart rate (HR) reserve. VO(2max), resting HR (rHR), exercise HR (eHR) and individual anaerobic threshold (IAT) were determined by treadmill and cycling ergometry respectively. Intraindividual coefficients of variation were extracted from the literature to distinguish random changes from training responses. Eight participants showed improvements in all variables. In 10 participants, one or two variables did not improve (VO(2max), rHR, eHR and IAT remained unchanged in four, four, three and one cases, respectively). At least one variable improved in each subject. Data indicate that ET adaptations might be detected in each individual using multiple variables of different adaptation levels and intensity domains. Nonresponse seems to occur frequently and might affect all variables. Further studies should investigate whether nonresponders improve with altered training. Furthermore, associations between patterns of nonresponse and health benefits from ET are worth considering.
TL;DR: The results suggest that in elite cyclists, Hbmass increases progressively with 3 weeks of natural altitude exposure, with greater increases expected as exposure persists.
Abstract: To determine the time course of hemoglobin mass (Hb(mass)) to natural altitude training, Hb(mass), erythropoietin [EPO], reticulocytes, ferritin and soluble transferrin receptor (sTfR) were measured in 13 elite cyclists during, and 10 days after, 3 weeks of sea level (n=5) or altitude (n=8, 2760 m) training. Mean Hb(mass), with a typical error of ∼2%, increased during the first 11 days at altitude (mean ± standard deviation 2.9 ± 2.0%) and was 3.5 ± 2.5% higher than baseline after 19 days. [EPO] increased 64.2 ± 18.8% after 2 nights at altitude but was not different from baseline after 12 nights. Hb(mass) and [EPO] did not increase in sea level. Reticulocytes (%) were slightly elevated in altitude at Days 5 and 12 (18.9 ± 17.7% and 20.4 ± 25.3%), sTfR was elevated at Day 12 (18.9 ± 15.0%), but both returned to baseline by Day 20. Hb(mass) and [EPO] decreased on descent to sea level while ferritin increased. The mean increase in Hb(mass) observed after 11 days (∼300 h) of altitude training was beyond the measurement error and consitent with the mean increase after 300 h of simulated live high:train low altitude. Our results suggest that in elite cyclists, Hb(mass) increases progressively with 3 weeks of natural altitude exposure, with greater increases expected as exposure persists.
TL;DR: WBC, administered 24 h after eccentric exercise, is ineffective in alleviating muscle soreness or enhancing muscle force recovery, and the results of this study indicate no increased risk of proprioceptive‐related injury following WBC.
Abstract: The purpose of this study was to investigate the effects of whole-body cryotherapy (WBC) on proprioceptive function, muscle force recovery following eccentric muscle contractions and tympanic temperature (TTY). Thirty-six subjects were randomly assigned to a group receiving two 3-min treatments of −110 ± 3 °C or 15 ± 3 °C. Knee joint position sense (JPS), maximal voluntary isometric contraction (MVIC) of the knee extensors, force proprioception and TTY were recorded before, immediately after the exposure and again 15 min later. A convenience sample of 18 subjects also underwent an eccentric exercise protocol on their contralateral left leg 24 h before exposure. MVIC (left knee), peak power output (PPO) during a repeated sprint on a cycle ergometer and muscles soreness were measured pre-, 24, 48 and 72 h post-treatment. WBC reduced TTY, by 0.3 °C, when compared with the control group (P<0.001). However, JPS, MVIC or force proprioception was not affected. Similarly, WBC did not effect MVIC, PPO or muscle soreness following eccentric exercise. WBC, administered 24 h after eccentric exercise, is ineffective in alleviating muscle soreness or enhancing muscle force recovery. The results of this study also indicate no increased risk of proprioceptive-related injury following WBC.
TL;DR: The ACL‐RSI showed good face validity, internal consistency, low floor and ceiling effects and high construct validity when evaluated against the TSK, K‐SES, MHLC‐C, KOOS, and ACL‐QoL scales, and the reproducibility was high and can be used to evaluate psychological factors relevant to returning to sport after ACL reconstruction surgery.
Abstract: Psychological factors may be a hindrance for returning to sport after an anterior cruciate ligament (ACL) reconstruction. The ACL-Return to Sport after Injury scale (ACL-RSI) measures athletes' emotions, confidence in performance, and risk appraisal in relation to return to sport. The aim of this study was to translate the ACL-RSI scale from English to Swedish and to examine some of the measurement properties of the Swedish version. The ACL-RSI was translated and culturally adapted. A professional expert group and five patients evaluated face validity. One hundred and eighty-two patients completed the translated ACL-RSI, a project-specific questionnaire, the Tampa Scale of Kinesiophobia (TSK), the Knee-Self-Efficacy Scale (K-SES), the Multidimensional Health Locus of Control (MHLC-C), the Knee injury and Osteoarthritis Outcome Score (KOOS), and the Anterior Cruciate Ligament-Quality of Life (ACL-QoL) questionnaires. Fifty-three patients answered the ACL-RSI twice to examine reproducibility. The ACL-RSI showed good face validity, internal consistency (Cronbach's alpha = 0.948), low floor and ceiling effects and high construct validity when evaluated against the TSK, K-SES, MHLC-C, KOOS, and ACL-QoL scales. The reproducibility was also high (intra-class correlation = 0.893). Therefore, the ACL-RSI can be used to evaluate psychological factors relevant to returning to sport after ACL reconstruction surgery.
TL;DR: IHG training improves nonlinear HRV, but not traditionalHRV, while reducing systolic and mean BP, and no significant changes were observed in traditional spectral or time‐domain measures of HRV or control participants.
Abstract: Hypertension is characterized by elevated blood pressure (BP) and autonomic dysfunction, both thought to be improved with exercise training. Isometric handgrip (IHG) training may represent a beneficial, time-effective exercise therapy. We investigated the effects of IHG training on BP and traditional and nonlinear measures of heart rate variability (HRV). Pre- and post-measurements of BP and HRV were determined in 23 medicated hypertensive participants (mean ± SEM, 66 ± 2 years) following either 8 weeks of IHG training (n = 13) or control (n = 10). IHG exercise consisted of four unilateral 2-min isometric contractions at 30% of maximal voluntary contraction, each separated by 4 min of rest. IHG training was performed 3 days/week for 8 weeks. IHG training decreased systolic BP (125 ± 3 mmHg to 120 ± 2 mmHg, P < 0.05) and mean BP (90 ± 2 mmHg to 87 ± 2 mmHg, P < 0.05), while sample entropy was increased (1.07 ± 0.1 to 1.35 ± 0.1, P < 0.05) and the fractal scaling distance score was decreased (0.34 ± 0.1 to 0.19 ± 0.1, P < 0.05). No significant changes were observed in traditional spectral or time-domain measures of HRV or control participants. IHG training improves nonlinear HRV, but not traditional HRV, while reducing systolic and mean BP. These results may highlight the benefits of IHG training for patients with primary hypertension.
TL;DR: The present study demonstrates a strong link among drop height, neuromuscular adaptation, and performance in SSC training, and the decision whether to apply SSC1 or SSC2 should depend on the specific requirements of the sports discipline.
Abstract: There is an ongoing discussion about how to improve jump performance most efficiently with plyometric training. It has been proposed that drop height influences the outcome, although longitudinal studies are missing. Based on cross-sectional drop jump studies showing height-dependent Hoffmann (H)-reflex activities, we hypothesized that the drop height should influence the neuromuscular activity and thus, the training result. Thirty-three subjects participated as a control or in one of two stretch-shortening cycle (SSC) interventions. Subjects either trained for 4 weeks doing drop jumps from 30, 50, and 75 cm drop heights (SSC1) or completed the same amount of jumps exclusively from 30 cm (SSC2). During training and testing (from 30, 50, and 75 cm), subjects were instructed to minimize the duration of ground contact and to maximize their rebound height. Rebound heights were significantly augmented after SSC1, but a trend was only observed after SSC2. In contrast, the duration of ground contact increased after SSC1 but decreased after SSC2. The performance index (rebound height/duration of ground contact) improved similarly after SSC1 (+14%) and SSC2 (+14%). Changes in performance were accompanied by neuromuscular adaptations: for SSC1, activity of the soleus increased toward take-off (between 120 and 170 ms after touchdown), whereas SSC2-trained subjects showed enhanced activity shortly after ground contact (20-70 ms after touch down). The present study demonstrates a strong link among drop height, neuromuscular adaptation, and performance in SSC training. As the improvement in the performance index was no different after SSC1 or SSC2, the decision whether to apply SSC1 or SSC2 should depend on the specific requirements of the sports discipline.
TL;DR: The data indicate that the stressors were encountered proportionately more by elite performers than non‐elite performers with some demands being in common and some unique to each group.
Abstract: In the study reported here, 12 sport performers (six elite and six non-elite) were interviewed with regard to organizational-related issues they had experienced in preparation for competition. Grounded theory procedures facilitated the development of a conceptual framework of organizational stressors consisting of five general dimensions: factors intrinsic to the sport, roles in the sport organization, sport relationships and interpersonal demands, athletic career and performance development issues, and organizational structure and climate of the sport. The data indicate that the stressors were encountered proportionately more by elite performers (#EPOS=315) than non-elite performers (#NPOS=228) with some demands being in common and some unique to each group. The results are discussed in relation to previous research and regarding their implications for professional practice.
TL;DR: Investigation of the incidence, type and distribution of stress fractures in professional male football players found younger age and intensive pre‐season training appear to be risk factors.
Abstract: The objective was to investigate the incidence, type and distribution of stress fractures in professional male football players. Fifty-four football teams, comprising 2379 players, were followed prospectively for 189 team seasons during the years 2001-2009. Team medical staff recorded individual player exposure and time-loss injuries. The first team squads of 24 clubs selected by UEFA as belonging to the 50 best European teams, 15 teams of the Swedish Super League and 15 teams playing their home matches on artificial turf pitches were included. In total, 51 stress fractures occurred during 1,180,000 h of exposure, giving an injury incidence of 0.04 injuries/1000 h. A team of 25 players can therefore expect one stress fracture every third season. All fractures affected the lower extremities and 78% the fifth metatarsal bone. Stress fractures to the fifth metatarsal bone, tibia or pelvis caused absences of 3-5 months. Twenty-nine percent of the stress fractures were re-injuries. Players that sustained stress fractures were significantly younger than those that did not. Stress fractures are rare in men's professional football but cause long absences. Younger age and intensive pre-season training appear to be risk factors.
TL;DR: Investigation of injury risk factors in junior tennis players found playing tennis more than 6 h/week was found to be a risk factor for back pain and a previous injury regardless of location was identified as an injury risk factor.
Abstract: The aim was to investigate injury risk factors in junior tennis players. Fifty-five players, 35 boys and 20 girls, answered a questionnaire about training habits, time of exposure, previous injuries and equipment factors. A battery of clinical tests and functional performance tests were also carried out. All tennis-related injuries that occurred during a 2-year period were identified and recorded. An injury was defined as an injury if it was impossible to participate in regular tennis training or playing matches during at least one occasion, a time loss injury. Potential injury risk factors were tested in a forward stepwise logistic regression model for injury. Thirty-nine players sustained totally 100 new and recurrent injuries. Injuries to the lower extremity were the most common ones (51%) followed by the upper extremity (24%) and the trunk (24%). Injured players performed more singles per week (P<0.0001) and played more tennis hours per year (P=0.016) than the uninjured players. Playing tennis more than 6 h/week was found to be a risk factor for back pain. A previous injury regardless of location was identified as an injury risk factor, and a previous injury to the back was a risk factor for back pain.
TL;DR: For instance, this article found that females exhibit greater frontal plane moments at the knee (internal knee adductor moments or external knee abduction moments) and favor the use of the knee extensors over the hip extENSors to attenuate impact forces when compared with males.
Abstract: During landing and cutting, females exhibit greater frontal plane moments at the knee (internal knee adductor moments or external knee abduction moments) and favor the use of the knee extensors over the hip extensors to attenuate impact forces when compared with males. However, it is not known when this biomechanical profile emerges. The purpose of this study was to compare landing biomechanics between sexes across maturation levels. One hundred and nineteen male and female soccer players (9-22 years) participated. Subjects were grouped based on maturational development. Lower extremity kinematics and kinetics were obtained during a drop-land task. Dependent variables included the average internal knee adductor moment and sagittal plane knee/hip moment and energy absorption ratios during the deceleration phase of landing. When averaged across maturation levels, females demonstrated greater internal knee adductor moments (0.06±0.03 vs 0.01±0.02 N m/kg m; P<0.005), knee/hip extensor moment ratios (2.0±0.1 vs 1.4±0.1 N m/kg m; P<0.001) and knee/hip energy absorption ratios (2.9±0.1 vs 1.96±0.1 N m/kg m; P<0.001) compared with males. Higher knee adductor moments combined with disproportionate use of knee extensors relative to hip extensors observed in females reflect a biomechanical pattern that increases anterior cruciate ligament loading. This biomechanical strategy already was established in pre-pubertal female athletes.
TL;DR: This is the first report that indicates an association between the chromosomal region 11q22 and the risk of ACL rupture and the two four‐variant haplotypes T‐1G‐A‐A and C‐2G‐G‐ G were significantly different between the CON and the ACL groups, and the CON group and the NON subgroup, respectively.
Abstract: As matrix metalloproteinases (MMPs) are critical to ligament homeostasis and integrity, the aim of this study was to investigate whether four functional polymorphisms within four MMP genes, which cluster on chromosome 11q22 associate with risk of ACL ruptures. Three hundred and forty-five [129 with ACL ruptures (ACL group) and 216 asymptomatic controls (CON group)] unrelated Caucasians were recruited for this case-control study. Fifty-four participants reported non-contact mechanisms of ACL rupture (NON subgroup). All participants were genotyped for the MMP10 C/T rs486055, MMP1 1G/2G rs1799750, MMP3 G/A rs679620 and MMP12 A/G rs2276109 variants. After adjusting for sex, age and weight, the AG and GG genotypes of the MMP12 rs2276109 variant were significantly (P=0.030) under-represented among the NON subgroup (14%), when compared with the CON group (26%). No other variants were significantly different between groups. Adjusted for the same confounders, the two four-variant haplotypes T-1G-A-A (CON 14%, ACL 9%, P=0.033) and C-2G-G-G (CON 14%, NON 5%, P=0.021) were significantly different between the CON and the ACL groups, and the CON group and the NON subgroup, respectively. This is the first report that indicates an association between the chromosomal region 11q22 and the risk of ACL rupture.
TL;DR: Improving hydration status by ad libitum consumption of water can enhance performance in young children exercising in the heat.
Abstract: We aimed to evaluate whether an intervention program emphasizing in increased fluid intake can improve exercise performance in children exercising in the heat. Ninety-two young athletes participated in the study (age: 13.8 ± 0.4 years, weight: 54.9 ± 1.5 kg). Thirty-one (boys: 13, girls: 18) children served as the control group (CON) and 61 (boys: 30, girls: 31) as the intervention (INT). Volunteers had free access to fluids. Hydration was assessed on the basis of first morning urine. A series of field tests were used to evaluate exercise performance. All tests occurred outdoors in the morning (mean ambient temperature=28 °C). After baseline testing, INT attended a lecture on hydration, and urine color charts were mounted in all bathrooms. Additionally, water accessibility was facilitated in training, dining and resting areas. Hydration status was improved significantly in the INT [USG: pre=1.031 ± 0.09, post=1.023 ± 0.012, P 0.05; urine osmolality (mOsm/kg water) 970 ± 38 vs 961 ± 38, P>0.05]. Performance in an endurance run was improved significantly only in INT (time for 600 m: pre=189 ± 5 s, post=167 ± 4 s, P<0.05). Improving hydration status by ad libitum consumption of water can enhance performance in young children exercising in the heat.