Effects of running on human Achilles tendon length-tension properties in the free and gastrocnemius components.

The elastic properties of the human Achilles tendon are important for locomotion; however, in vitro tests suggest that repeated cyclic contractions lead to tendon fatigue - an increase in length in response to stress applied. In vivo experiments have not, however, demonstrated mechanical fatigue in the Achilles tendon, possibly due to the limitations of using two-dimensional ultrasound imaging to assess tendon strain. This study used freehand three-dimensional ultrasound (3DUS) to determine whether the free Achilles tendon (calcaneus to soleus) or the gastrocnemius tendon (calcaneus to gastrocnemius) demonstrated tendon fatigue after running exercise. Participants (N=9) underwent 3DUS scans of the Achilles tendon during isometric contractions at four ankle torque levels (passive, and 14, 42 and 70 N m) before and after a 5 km run at a self-selected pace (10-14 km h(-1)). Running had a significant main effect on the length of the free Achilles tendon (P<0.01) with a small increase in length across the torque range. However, the mean lengthening effect was small (<1%) and was not accompanied by a change in free tendon stiffness. There was no significant change in the length of the gastrocnemius tendon or the free tendon cross-sectional area. While the free tendon was shown to lengthen, the lack of change in stiffness suggests the tendon exhibited mechanical creep rather than fatigue. These effects were much smaller than those predicted from in vitro experiments, possibly due to the different loading profile encountered and the ability of the tendon to repair in vivo.

Chronic tendinopathy: effectiveness of eccentric exercise.

OBJECTIVES: To determine the effectiveness of eccentric exercise (EE) programmes in the treatment of common tendinopathies. DATA SOURCES: Relevant randomised controlled trials (RCTs) were sourced using the OVID website databases: MEDLINE (1966-Jan 2006), CINAHL (1982-Jan 2006), AMED (1985-Jan 2006), EMBASE (1988-Jan 2006), and all EBM reviews--Cochrane DSR, ACP Journal Club, DARE, and CCTR (Jan 2006). The Physiotherapy Evidence Database (PEDro) was also searched using the keyword: eccentric. REVIEW METHODS: The PEDro and van Tulder scales were employed to assess methodological quality. Levels of evidence were then obtained according to predefined thresholds: Strong--consistent findings among multiple high-quality RCTs. Moderate--consistent findings among multiple low-quality RCTs and/or clinically controlled trials (CCTs) and/or one high-quality RCT. Limited--one low-quality RCT and/or CCT. Conflicting--inconsistent findings among multiple trials (RCTs and/or CCTs). No evidence-no RCTs or CCTs. RESULTS: Twenty relevant studies were sourced, 11 of which met the inclusion criteria. These included studies of Achilles tendinopathy (AT), patella tendinopathy (PT) and tendinopathy of the common wrist extensor tendon of the lateral elbow (LET). Limited levels of evidence exist to suggest that EE has a positive effect on clinical outcomes such as pain, function and patient satisfaction/return to work when compared to various control interventions such as concentric exercise (CE), stretching, splinting, frictions and ultrasound. Levels of evidence were found to be variable across the tendinopathies investigated. CONCLUSIONS: This review demonstrates the dearth of high-quality research in support of the clinical effectiveness of EE over other treatments in the management of tendinopathies. Further adequately powered studies that include appropriate randomisation procedures, standardised outcome measures and long-term follow-up are required.

Regional bone geometry of the tibia in triathletes and stress reactions--an observational study.

OBJECTIVES: The association between tibial morphology and tibial stress fractures or tibial stress syndrome was examined in triathletes with an unusually high incidence of these injuries. DESIGN: A cross-sectional study design examined associations between tibial geometry from MRI images and training and injury data between male and female triathletes and between stress fracture (SF) and non-stress fracture (NSF) groups. METHODS: Fifteen athletes (7 females, 8 males) aged 17-23 years who were currently able to train and race were recruited from the New Zealand Triathlete Elite Development Squad. Geometric measurements were taken at 5 zones along the tibia using MRI and compared between symptomatic and asymptomatic tibiae subjects. RESULTS: SF tibiae displayed either oedema within the cancellous bone and/or stress fracture on MRI. When collapsed across levels, symptomatic tibiae had thicker medial cortices (F1,140=9.285, p=0.003), thicker lateral cortices (F1,140=10.129, p=0.002) and thinner anterior cortices (F1,140=14.517, p=0.000) than NSF tibiae. Only medial cortex thickness in SF tibia was significantly different (F4,140=3.358, p=0.012) at different levels. Follow-up analysis showed that athletes showing oedema within the cancellous bone and/or stress fracture on MRI had, within 2 years of analysis, subsequently taken time off training and racing due a tibial stress fracture. CONCLUSIONS: The thinner anterior cortex in SF tibiae is associated with a stress reaction in these triathletes.

Analysis of knee flexion angles during 2 clinical versions of the heel raise test to assess soleus and gastrocnemius function.

STUDY DESIGN: Controlled laboratory study, using a repeated-measures, counterbalanced design. OBJECTIVES: To provide estimates on the average knee angle maintained, absolute knee angle error, and total repetitions performed during 2 versions of the heel raise test. BACKGROUND: The heel raise test is performed in knee extension (EHRT) to assess gastrocnemius and knee flexion (FHRT) for soleus. However, it has not yet been determined whether select knee angles are maintained or whether total repetitions differ between the clinical versions of the heel raise test. METHODS: Seventeen healthy males and females performed maximal heel raise repetitions in 0° (EHRT) and 30° (FHRT) of desired knee flexion. The average angle maintained and absolute error at the knee during the 2 versions, and total heel raise repetitions, were measured using motion analysis. Participants' kinematic measures were fitted into a generalized estimation equation model to provide estimates on EHRT and FHRT performance applicable to the general population. RESULTS: The model estimates that average angles of 2.2° and 30.7° will be maintained at the knee by the general population during the EHRT and the FHRT, with an absolute angle error of 3.4° and 2.5°, respectively. In both versions, 40 repetitions should be completed. However, the average angles maintained by participants ranged from -6.3° to 21.6° during the EHRT and from 22.0° to 43.0° during the FHRT, with the highest absolute errors in knee position being 25.9° and 33.5°, respectively. CONCLUSION: On average, select knee angles will be maintained by the general population during the select heel raise test versions, but individualized performance is variable and total repetitions do not distinguish between versions. Clinicians should, therefore, interpret select heel raise test outcomes with caution when used to respectively assess and rehabilitate soleus and gastrocnemius function.

Pre-race health status and medical events during the 2005 World Adventure Racing Championships.

Adventure racing is a wilderness multisport endurance event with the potential for significant injury and illness; however specific contributing factors have not been extensively studied. A prospective cross-sectional study was conducted that collected data during the 2005 Adventure Racing World Championship on pre-, in- and post-race injury and illness and determined pre-race training volumes and health profiles in 184 athletes (46 teams of 4 athletes). In the 6 months prior to the event, 79.9% of athletes reported an injury or illness. Fifty-nine cases of injury or illness were recorded during the race; representing an overall rate of 2.5 injuries per 1000 race-hours and 1.0 illness per 1000 race-hours. This incidence could be considered low compared to some sports, but the rate is tempered by the time on course exposure of 16,774 race-hours. Respiratory conditions were the single-most common condition resulting in race withdrawal. There was a moderate, but not statistically significantly, association (OR=4.61, p=0.083, 95% CI 0.82-26.08) between pre-race illness and in-race illness. Forty-four (95%) teams responded to a post-race questionnaire with 30% of the athletes reporting a new injury and 12% reporting a new illness in the week following the race. Understanding contributing factors to injury and illness during adventure racing will aid implementation of race medical coverage, preventative strategies and increase participation and performance.

Scientific bases and clinical utilisation of the calf-raise test.

BACKGROUND: Athletes commonly sustain injuries to the triceps surae muscle-tendon unit. The calf-raise test (CRT) is frequently employed in sports medicine for the detection and monitoring of such injuries. However, despite being widely-used, a recent systematic review found no universal consensus relating to the test's purpose, parameters, and standard protocols. OBJECTIVES: The purpose of this paper is to provide a clinical perspective on the anatomo-physiological bases underpinning the CRT and to discuss the utilisation of the test in relation to the structure and function of the triceps surae muscle-tendon unit. DESIGN: Structured narrative review. METHODS: Nine electronic databases were searched using keywords and MESH headings related to the CRT and the triceps surae muscle-tendon unit anatomy and physiology. A hand-search of reference lists and relevant journals and textbooks complemented the electronic search. SUMMARY: There is evidence supporting the clinical use of the CRT to assess soleus and gastrocnemius, their shared aponeurosis, the Achilles tendon, and the combined triceps surae muscle-tendon unit. However, employing the same clinical test to assess all these structures and their associated functions remains challenging. CONCLUSIONS: Further refinement of the CRT for the triceps surae muscle-tendon unit is needed. This is vital to support best practice utilisation, standardisation, and interpretation of the CRT in sports medicine.

Raising the standards of the calf-raise test: a systematic review.

The calf-raise test is used by clinicians and researchers in sports medicine to assess properties of the calf muscle-tendon unit. The test generally involves repetitive concentric-eccentric muscle action of the plantar-flexors in unipedal stance and is quantified by the number of raises performed. Although the calf-raise test appears to have acceptable reliability and face validity, and is commonly used for medical assessment and rehabilitation of injuries, no universally acceptable test parameters have been published to date. A systematic review of the existing literature was conducted to investigate the consistency as well as universal acceptance of the evaluation purposes, test parameters, outcome measurements and psychometric properties of the calf-raise test. Nine electronic databases were searched during the period May 30th to September 21st 2008. Forty-nine articles met the inclusion criteria and were quality assessed. Information on study characteristics and calf-raise test parameters, as well as quantitative data, were extracted; tabulated; and statistically analysed. The average quality score of the reviewed articles was 70.4+/-12.2% (range 44-90%). Articles provided various test parameters; however, a consensus was not ascertained. Key testing parameters varied, were often unstated, and few studies reported reliability or validity values, including sensitivity and specificity. No definitive normative values could be established and the utility of the test in subjects with pathologies remained unclear. Although adapted for use in several disciplines and traditionally recommended for clinical assessment, there is no uniform description of the calf-raise test in the literature. Further investigation is recommended to ensure consistent use and interpretation of the test by researchers and clinicians.