Peter Malliaras

Hip flexibility and strength measures: reliability and association with athletic groin pain

Objective: Groin pain commonly affects football players and can be associated with prolonged recovery periods. Understanding the relationship between groin pain and reliable measures of hip flexibility and strength may facilitate the development of optimal rehabilitation and prevention strategies. In this study, the reliability and association with athletic groin pain of hip flexibility and strength measures were investigated. Methods: A cohort of 29 football players (15–21 years) participating in junior elite competitions (Australian Rules football and soccer) were recruited. The intra-rater reliability (n  =  13) and inter-rater reliability (n  =  12) of various hip flexibility (bent knee fall out test, hip internal rotation, hip external rotation) and strength (hip abduction, hip internal rotation, hip external rotation, hip adduction (squeeze test)) measures were investigated using intraclass correlation coefficients (ICC). Reliable hip flexibility and strength measures were compared between football players with (n  =  10) and without (n  =  19) groin pain. Results: The bent knee fall out test, hip internal rotation flexibility and the squeeze test demonstrated acceptable (ICC>0.75) intra-rater and inter-rater reliability, while hip external rotation flexibility and hip abduction strength demonstrated acceptable intra-rater but not inter-rater reliability. Hip internal and external rotation strength tests were not found to be reliable. Football players with groin pain had significantly reduced force production on the squeeze test (p>0.05). Conclusion: Several hip flexibility and strength measures were found to be reliable. Only the squeeze test discriminated between football players with and without groin pain.

Neovascularization and pain in abnormal patellar tendons of active jumping athletes

Objective:The aim of this study was to investigate tendon pain in abnormal patellar tendons with and without neovascularization. Study design:Comparative design. Setting:Multidisciplinary tendon study group at a competitive volleyball venue. Participants:One hundred eleven volleyball players volunteered to participate in the study. Main Outcome Measures:Subjects’ patellar tendons were imaged with ultrasound, with and without Doppler. Tendons that were imaging abnormal were categorized according the presence of tendon neovascularization. Subjects completed 3 pain scales that examined function (Victorian Institute of Sport Assessment score, 100-point maximum), pain with tendon load (decline squat, visual analogue scale, 100-mm maximum), and maximum pain for the previous week (visual analogue scale, 100-mm maximum). A 1-tailed Mann-Whitney U test compared pain scores in abnormal tendons without neovascularization to abnormal tendons with neovascularization. Results:Functional scores were lower (Victorian Institute of Sport score, median, 78; P = 0.045) and pain scores under tendon load were greater (decline squat pain, median, 19; P = 0.048) in subjects with abnormal tendons with neovascularization than subjects with abnormal tendons without neovascularization (Victorian Institute of Sport Assessment score, median, 87; decline squat pain, median, 0). Conclusions:This study indicates that the presence of neovascularization in abnormal patellar tendons is associated with greater tendon pain compared with abnormal tendons without neovascularization in active jumping athletes.

Gluteal muscle activity and patellofemoral pain syndrome: a systematic review

Objective There is growing evidence to support the association of gluteal muscle strength deficits in individuals with patellofemoral pain syndrome (PFPS) and the effectiveness of gluteal strengthening when treating PFPS. In additiona, an impressive body of work evaluating gluteal electromyography (EMG) has recently emerged, further supporting the importance of gluteal muscle function in PFPS. This systematic review synthesises these EMG findings in order to better understand the role of gluteal muscle activity in the aetiology, presentation and management of PFPS. Methods MEDLINE, EMBASE, CINAHL, Web of Knowledge and Google Scholar databases were searched in September 2011 for prospective and case–control studies evaluating the association of gluteal EMG with PFPS. Two independent reviewers assessed each paper for inclusion and quality. Means and SDs were extracted from each included study to allow effect size calculations and comparison of results. Results Ten case–control, but no prospective studies were identified. Moderate-to-strong evidence indicates gluteus medius (GMed) activity is delayed and of shorter duration during stair negotiation in PFPS sufferers. In addition, limited evidence indicates GMed activity is delayed and of shorter duration during running, and gluteus maximus (GMax) activity is increased during stair descent. Conclusions Delayed and shorter duration of GMed EMG may indicate impaired ability to control frontal and transverse plane hip motion. Further research evaluating the value of gluteal muscle activity screening in identifying individuals most likely to develop PFPS, and the effectiveness of interventions targeting changes to gluteal muscle activation patterns is needed.

Return to Competitive Play After Hamstring Injuries Involving Disruption of the Central Tendon

Background: The hamstring muscles are the most commonly injured muscle group in many different sports. Recovery time is often unpredictable and prolonged, and recurrent injury is common. Hypothesis: Hamstring injuries that disrupt the central tendon enclosed within the muscle belly require a longer recovery time than do injuries involving only muscle, epimysial fascia, or the musculotendinous junction. Study Design: Cohort study; Level of evidence, 3. Methods: Injury records from professional sports teams were reviewed to determine the length of recovery from each hamstring injury that occurred over a 24-month period. The integrity of the central tendon on magnetic resonance imaging (MRI) was retrospectively reviewed for each case. The association between central tendon disruption on MRI and recovery time was determined. Results: There were 62 hamstring injuries included for analysis; 45 (72%) involved the biceps femoris, 11 (18%) involved the semimembranosus, and 6 (10%) involved the semitendinosus. Central tendon disruption was identified in 12 (45%) of the biceps femoris injuries and in none of the injuries to the other 2 muscles. Three of these injuries were treated surgically, with a median recovery time of 91 days. The median (interquartile range [IQR]) recovery times for those remaining biceps femoris injuries with and without central tendon disruption were 21 days (IQR, 9-28) and 72 days (IQR, 42-109), respectively (P < .01). Conclusion: Disruption of the central tendon in injuries to the biceps femoris results in a significantly longer recovery time than injuries that do not disrupt the central tendon. This highlights the distinction between injury to the hamstring muscle and injury to the hamstring tendon, which is underappreciated as being a distinct entity when injury involves the enclosed central portion of the tendon.

Vascularity and pain in the patellar tendon of adult jumping athletes: a 5 month longitudinal study

Background: This study investigated changes in tendon vascularity in 102 (67 men and 35 women) volleyball players over a 6 month competitive season. Methods: Athletes were examined with both grey scale ultrasound and standardised colour Doppler settings. Vessel length and pain were measured each month on five separate occasions. Vascular tendons were divided into (i) those that were vascular on all occasions (persistent vascularity) and (ii) those that were vascular on more than two but less than five occasions (intermittent vascularity). Results: A total of 41 of the 133 abnormal tendons were vascular on two or more occasions. Of these, 16 had persistent vascularity and 25 had intermittent vascularity. There was no significant difference in the prevalence of vascularity between men and women. None of the tendons had a pattern of vascularity over the season that could be clearly interpreted as the onset or resolution of vascularity. Subjects with changes in both tendons were more likely to have persistent vascularity (p = 0.045). Vessels were longer in tendons with persistent vascularity (p<0.000) and pain was significantly greater (p = 0.043) than in tendons with intermittent vascularity. Tendons with intermittent vascularity had similar pain scores on all days, whether or not they had detectable blood flow. Conclusions: These data suggest that the presence of blood vessels is more likely to be the source of pain than the blood flow in them.

The prevalence and clinical significance of sonographic tendon abnormalities in asymptomatic ballet dancers: a 24-month longitudinal study

Introduction Sonographic abnormalities of the achilles and patellar tendons are common findings in athletes, and tendinopathy is a common cause of pain and disability in athletes. However, it is unclear whether the sonographic changes are pathological or adaptive, or if they predict future injury. We undertook a cohort study to determine what sonographic features of the achilles and patellar tendons are consistent with changes as a result of ballet training, and which may be predictive of future development of disabling tendon symptoms. Methods The achilles and patellar tendons of 79 (35 male, 44 female) professional ballet dancers (members of the English Royal Ballet) were examined with ultrasound, measuring proximal and distal tendon diameters and assessing for the presence of hypoechoic change, intratendon defects, calcification and neovascularity. All subjects were followed for 24 months for the development of patellar tendon or achilles-related pain or injury severe enough to require time off from dancing. Results Sonographic abnormalities were common among dancers, both male and female, and in both achilles and patellar tendons. Disabling tendon-related symptoms developed in 10 dancers and 14 tendons: 7 achilles (3 right, 4 left) and 7 patellar (2 right, 5 left). The presence of moderate or severe hypoechoic defects was weakly predictive for the development of future disabling tendon symptoms (p=0.0381); there was no correlation between any of the other sonographic abnormalities and the development of symptoms. There was no relationship between achilles or patellar tendons’ diameter, either proximal or distal, with an increased likelihood of developing tendon-related disability. Conclusion The presence of sonographic abnormalities is common in ballet dancers, but only the presence of focal hypoechoic changes predicts the development of future tendon-related disability. This suggests that screening of asymptomatic individuals may be of use in identifying those who are at higher risk of developing tendon-related disability, which may in turn allow targeted modifications of training or other preventative regimens.

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.

Prospective study of change in patellar tendon abnormality on imaging and pain over a volleyball season

Objective: Patellar tendon injury, defined by tendon abnormality (TA) on imaging and by pain, is common among volleyball players, but little is known about change in this injury over a volleyball season. Increased activity in the season compared with the off season may result in the development of TA and/or pain. This study investigated the behaviour of TA and pain over a competitive volleyball season. Methods: Tendon abnormality and pain were measured in 101 volleyball players at the beginning and end of a season. Pain was measured with the single leg decline squat test, which loads the patellar tendon, and TA was detected with ultrasound imaging. Hours of weekly activity were measured and compared during the season and the off season. The proportion of tendons that underwent development and resolution in TA and/or pain over the season was investigated. Results: Hours of weekly activity was greater during the season than in the off season. Most of the tendons investigated (66.3%) did not undergo a change in TA or pain over the season. Tendon abnormality and/or pain developed in 16.6% of tendons and resolved in 11.2%. Conclusions: The tendons of volleyball players respond variably to the increased load over the season. Change in TA and pain does not appear to be entirely dependent upon load.

Patellar tendon adaptation in relation to load-intensity and contraction type.

BACKGROUND Loading leads to tendon adaptation but the influence of load-intensity and contraction type is unclear. Clinicians need to be aware of the type and intensity of loading required for tendon adaptation when prescribing exercise. The aim of this study was to investigate the influence of contraction type and load-intensity on patellar tendon mechanical properties. METHOD Load intensity was determined using the 1 repetition maximum (RM) on a resistance exercise device at baseline and fortnightly intervals in four randomly allocated groups of healthy, young males: (1) control (no training); (2) concentric (80% of concentric-eccentric 1RM, 4×7-8); (3) standard load eccentric only (80% of concentric-eccentric 1RM, 4×12-15 repetitions) and (4) high load eccentric (80% of eccentric 1RM, 4×7-8 repetitions). Participants exercised three times a week for 12 weeks on a leg extension machine. Knee extension maximum torque, patellar tendon CSA and length were measured with dynamometry and ultrasound imaging. Patellar tendon force, stress and strain were calculated at 25%, 50%, 75% and 100% of maximum torque during isometric knee extension contractions, and stiffness and modulus at torque intervals of 50-75% and 75-100%. Within group and between group differences in CSA, force, elongation, stress, strain, stiffness and modulus were investigated. The same day reliability of patellar tendon measures was established with a subset of eight participants. RESULTS Patellar tendon modulus increased in all exercise groups compared with the control group (p<0.05) at 50-75% of maximal voluntary isometric contraction (MVIC), but only in the high eccentric group compared with the control group at 75-100% of MVIC (p<0.05). The only other group difference in tendon properties was a significantly greater increase in maximum force in the high eccentric compared with the control group (p<0.05). Five repetition maximum increased in all groups but the increase was significantly greater in the high load eccentric compared with the other exercise groups (p<0.05). CONCLUSION Load at different intensity levels and contraction types increased patellar tendon modulus whereas muscle strength seems to respond more to load-intensity. High load eccentric was, however, the only group to have significantly greater increase in force, stiffness and modulus (at the highest torque levels) compared with the control group. The effects and clinical applicability of high load interventions needs to be investigated further.

Hamstring exercises for track and field athletes: injury and exercise biomechanics, and possible implications for exercise selection and primary prevention

Hamstring strain injuries are the most prevalent muscle injuries in track and field (TF). These injuries often cause prolonged symptoms and a high risk of re-injury. Strengthening of the hamstring muscles has been recommended for injury prevention. The authors review the possible role of eccentric training in TF hamstring injury prevention and introduce exercise classification criteria to guide clinicians in designing strengthening programmes adapted to TF. The principles exposed may serve as a foundation for future development and application of new eccentric programmes to decrease the high incidence of this type of injury in other sports.