Volume of physical activity and injury occurrence in young basketball players

Participation in organised, competitive physical activity by young athletes is increasing rapidly. This is concurrent with an increase in sporting injuries in the young population. This pilot study aimed to compare the weekly volume and types of physical activity in young basketball players injured and not injured during the season. Detailed physical activity and injury data were prospectively collected in 46 school-level basketball players aged 14 to 18 years. Participants completed physical activity logs which documented the type of physical activity undertaken, what the activity consisted of (i.e. training, competition) and the level at which it was played on a daily basis. Allied health staff completed a weekly injury form. Results showed that injured and uninjured athletes participated in a similar volume of total weekly physical activity over the season. However, injured athletes (p = 0.04) and athletes who specifically sustained overuse injuries (p = 0.01) participated in a greater amount of basketball refereeing than uninjured athletes. Based on these findings it was concluded that greater participation in running-type physical activity such as refereeing, as an addition to training and competition, may predispose the young basketball player to increased injury risk. Future research using larger sample sizes are required to further investigate the role of participation volume and type on injury occurrence in adolescent athletes.

Older people playing ball : what is the risk of falling and injury?

Increasing physical activity amongst seniors is important for public health, yet guidance is needed to minimise injury risks. To describe the incidence of falls/injuries in a walking team ball game (Lifeball) designed for seniors, a prospective cohort study was undertaken amongst community dwelling Lifeball participants in Australia. Players completed a telephone survey soon after commencing Lifeball (2004) and 12 months later (2005). Attendance and incident records were audited for the period. Subjects joined a Lifeball group with opportunity to play at least once per week. Baseline was completed by 284 players aged between 40 and 96 years (mean 67 years), with most (83.8%, 238/284) female. Of 263 followed up, the average attendances was 25, with 19.3% attending on fewer than 4 occasions and 14.3% attending 52 or more times. Most (93.9%) reported no injuries requiring medical attention. However, 16 (6.1%) had injuries requiring medical attention and their 27 injuries represent an injury rate of 3.3 per 1000 hours of participation. Twenty participants (7.6%) had a Lifeball fall equating to a fall rate of 2.8 per 1000 hours of participation. Falls in Lifeball were not associated with measured predictors (age, gender, falls history, perceived falls risk or hours played). Incident records showed a trip/stumble involving rushing, walking backwards, or overextending (all against rules) as common falling causes. Lifeball is not ‘risk free’ however due to a lack of comparative data it is difficult to compare injury rate to relevant activities. Prevention of injury should concentrate on enforcing safety rules.

Anthropometric risk factors for patellar tendon injury among volleyball players

Objective: Abnormal imaging in the patellar tendon reveals pathology that is often associated with knee pain. Anthropometric measures of body size and mass, such as height, weight and waist-to-hip ratio (WHR), have been individually associated with abnormal imaging. The aim of this study was to investigate the anthropometric factors that have the strongest relationship with abnormal imaging in volleyball players.

Methods: Height, weight, body mass index (BMI), waist girth, hip girth and WHR were measured in a cohort of 113 competitive volleyball players (73 men, 40 women). The univariate (ANOVA) and multivariable (discriminant function analysis) association between abnormal imaging and these anthropometric factors were investigated.

Results: No significant association was found in the female volleyball players. A significant univariate association was observed between abnormal imaging and heavier weight, greater BMI, larger waist and hip girth and larger WHR in the male volleyball players. Waist girth was the only factor that retained this association in a multivariable model (p<0.05).

Conclusions: Men with a waist girth greater than 83 cm seem to be at greater risk of developing patellar tendon pathology. There may be both mechanical and biochemical reasons for this increased risk.

Calcineurin-Aα alpha activation enhances the structure and function of regenerating muscles after myotoxic injury

Calcineurin signaling is essential for successful muscle regeneration. Although calcineurin inhibition compromises muscle repair, it is not known whether calcineurin activation can enhance muscle repair after injury. Tibialis anterior (TA) muscles from adult wild-type (WT) and transgenic mice overexpressing the constitutively active calcineurin-Aα transgene under the control of the mitochondrial creatine kinase promoter (MCK-CnAα*) were injected with the myotoxic snake venom Notexin to destroy all muscle fibers. The TA muscle of the contralateral limb served as the uninjured control. Muscle structure was assessed at 5 and 9 days postinjury, and muscle function was tested in situ at 9 days postinjury. Calcineurin stimulation enhanced muscle regeneration and altered levels of myoregulatory factors (MRFs). Recovery of myofiber size and force-producing capacity was hastened in injured muscles of MCK-CnAα* mice compared with control. Myogenin levels were greater 5 days postinjury and myocyte enhancer factor 2a (MEF2a) expression was greater 9 days postinjury in muscles of MCK-CnAα* mice compared with WT mice. Higher MEF2a expression in regenerating muscles of MCK-CnAα* mice 9 days postinjury may be related to an increase of slow fiber genes. Calcineurin activation in uninjured and injured TA muscles slowed muscle contractile properties, reduced fatigability, and enhanced force recovery after 4 min of intermittent maximal stimulation. Therefore, calcineurin activation can confer structural and functional benefits to regenerating skeletal muscles, which may be mediated in part by differential expression of MRFs.

Activated calcineurin ameliorates contraction-induced injury to skeletal muscles of mdx dystrophic mice

Utrophin expression is regulated by calcineurin and up-regulating utrophin can decrease the susceptibility of dystrophic skeletal muscle to contraction-induced injury. We overexpressed the constitutively active calcineurin-A α in skeletal muscle of mdx dystrophic mice (mdx CnA*) and examined the tibialis anterior muscle to determine whether the presence of activated calcineurin promotes resistance to muscle damage after lengthening contractions. Two stretches (10 s apart) of 40% strain relative to muscle fibre length were initiated from the plateau of a maximal isometric tetanic contraction. Muscle damage was assessed 1, 5 and 15 min later by the deficit in maximum isometric force and by quantifying the proportion of muscle fibres staining positive for intracytoplasmic albumin. The force deficit at all time points after the lengthening contractions was approximately 80% in mdx muscles and 30% in mdxCnA* muscles. The proportion of albumin-positive fibres was significantly less in control and injured muscles from mdxCnA* mice than from mdx mice. Compared with mdx mice, mean fibre cross-sectional area was 50% less in muscles from mdxCnA* mice. Furthermore, muscles frommdxCnA* mice exhibited a higher proportion of fibres expressing the slow(er) myosin heavy chain (MyHC) I and IIa isoforms, prolonged contraction and relaxation times, lower absolute and normalized maximum forces, and a clear leftward shift of the frequency–force relationship with greater force production at lower stimulation frequencies. These are structural and functional markers of a slower muscle phenotype. Taken together, our findings show that muscles from mdxCnA* mice have a smaller mean fibre cross-sectional area, a greater sarcolemmal to cytoplasmic volume ratio, and an increase in utrophin expression, promoting an attenuated susceptibility to contraction-induced injury. We conclude that increased calcineurin activity may confer functional benefits to dystrophic skeletal muscles.

Effects of ovariectomy and estrogen on ischemia-reperfusion injury in hindlimbs of female rats

The effects of estrogen and ovariectomy on indexes of muscle damage after 2 h of complete hindlimb ischemia and 2 h of reperfusion were investigated in female Sprague-Dawley rats. The rats were assigned to one of three experimental groups: ovariectomized with a 17-estradiol pellet implant (OE), ovariectomized with a placebo pellet implant (OP), or control with intact ovaries (R). It was hypothesized that following ischemia-reperfusion (I/R), muscle damage indexes [serum creatine kinase (CK) activity, calpain-like activity, inflammatory cell infiltration, and markers of lipid peroxidation (thiobarbituric-reactive substances)] would be lower in the OE and R rats compared with the OP rats due to the protective effects of estrogen. Serum CK activity following I/R was greater (P < 0.01) in the R rats vs. OP rats and similar in the OP and OE rats. Calpain-like activity was greatest in the R rats (P < 0.01) and similar in the OP and OE rats. Neutrophil infiltration was assessed using the myeloperoxidase (MPO) assay and immunohistochemical staining for CD43-positive (CD43+) cells. MPO activity was lower (P < 0.05) in the OE rats compared with any other group and similar in the OP and R rats. The number of CD43+ cells was greater (P < 0.01) in the OP rats compared with the OE and R rats and similar in the OE and R rats. The OE rats had lower (P < 0.05) thiobarbituric-reactive substance content following I/R compared with the R and OP rats. Indexes of muscle damage were consistently attenuated in the OE rats but not in the R rats. A 10-fold difference in serum estrogen content may mediate this. Surprisingly, serum CK activity and muscle calpain-like activity were lower (P < 0.05) in the OP rats compared with the R rats. Increases in serum insulin-like growth factor-1 content (P < 0.05) due to ovariectomy were hypothesized to account for this finding. Thus both ovariectomy and estrogen supplementation have differential effects on indexes of I/R muscle damage.

Injury and burnout in Australian athletes

The relationship between injury and burnout in a sample of 264 local to international Australian athletes (124 men and 140 women) was studied. Injury can be a stressful experience for athletes; coupled with the demands of rehabilitation, it could increase feelings of burnout. Experiencing more than one injury could have a cumulative effect on feelings of burnout. Alternatively, for some athletes the break from training or competing caused by an injury could alleviate burnout symptoms. Participants completed a demographic questionnaire and a modified version of the Maslach Burnout Inventory. Independent sample t tests indicated that currently injured athletes (n = 150) had significantly lower mean Burnout scores than currently uninjured athletes (n = 113). Small, but statistically significant, positive correlations were found between number of injuries and Burnout scores. Possible explanations are that injury provides a temporary break from intense sporting involvement and, thus, lower scores on Burnout, but multiple injuries might have a cumulative effect on burnout.

Management of tendinopathy

Overuse disorders of tendons, or tendinopathies, present a challenge to sports physicians, surgeons, and other health care professionals dealing with athletes. The Achilles, patellar, and supraspinatus tendons are particularly vulnerable to injury and often difficult to manage successfully. Inflammation was believed central to the pathologic process, but histopathologic evidence has confirmed the failed healing response nature of these conditions. Excessive or inappropriate loading of the musculotendinous unit is believed to be central to the disease process, although the exact mechanism by which this occurs remains uncertain. Additionally, the location of the lesion (for example, the midtendon or osteotendinous junction) has become increasingly recognized as influencing both the pathologic process and subsequent management.

The mechanical, vascular, neural, and other theories that seek to explain the pathologic process are explored in this article. Recent developments in the nonoperative management of chronic tendon disorders are reviewed, as is the rationale for surgical intervention. Recent surgical advances, including minimally invasive tendon surgery, are reviewed. Potential future management strategies, such as stem cell therapy, growth factor treatment, and gene transfer, are also discussed.

Metamemory training for memory disorders in adults with a closed head injury

The purpose of the present study was to investigate the efficacy of a memory and metamemory training program on memory performance and metamemory judgement accuracy in adults with a closed head injury. A multiple baseline across subjects design was used with six subjects. All subjects were seen at least two years post-injury. Training included general metamemory information about the nature of memory, use of a specific memory strategy to assist verbal recall (to Preview, Question, Read, State and Test- PQRST), specific metamemory information about the strategy, and a self instruction procedure (WTSC- What is the task, Select a strategy to use, Try out strategy, Check to evaluate strategy effectiveness). During the training period all subjects recalled greater than fifty percent of paragraph ideas while using PQRST. Follow-up tests showed that five of the six subjects maintained recall levels but a gradual decrease in slope was observed over eight weeks post-training. Tests of recall, recognition and metamemory judgements on Sentence and Action Tasks were used to evaluate generalisation of training. Two subjects showed improved recall and two subjects showed improved recognition performance. In addition, four subjects demonstrated greater metamemory judgement accuracy about recognition performance following training. Improved performance post-training was also observed for three subjects on the Rivermead Behavioral Memory Test and the Logical Memory subtest of the Wechsler Memory Scale-Revised, greater than that expected for repeated testing. Several factors were identified as having a role in subjects’ ability to benefit from training.