Whole body vibration for chronic patellar tendinopathy: A randomized equivalence trial.

Purpose: Whole body vibration (WBV) triggers anabolic responses in various tissues, including tendons, without requiring high force production. In this waitlist-controlled equivalence trial, we tested its clinical effectiveness as an alternative treatment for patellar tendinopathy against conventional heavy slow resistance training (HSR). Methods: Thirty-nine patients were randomized to either 3 months of WBV training (n = 13), HSR training (n = 11), or a waitlist control (WLC) group (n = 15). In a partly cross-over design, 14 patients of the WLC group were redistributed to one of the two intervention groups (5 in WBV, 9 in HSR). Pre- and post-intervention testing included pain assessments (VAS), functional limitations (VISA-P), knee extension strength and tendon morphological, mechanical and material properties. Follow-up measurements (VAS, VISA-P) were performed in the WBV and HSR groups 6 months after the intervention. Results: Comparisons with the WLC group revealed significant improvements in VISA-P and VAS scores after HSR (41%, p = 003; 54%, p = 0.005) and WBV (22%, p = 0.022; 56%, p = 0.031) training. These improvements continued until follow-up (HSR: 43%, 56%; WBV: 24%, 37%). Pre-post improvements in VAS scores were equivalent between WBV and HSR groups but inconclusive for the VISA-P score and all pre-test to follow up comparisons. The mid-tendon cross-sectional area was significantly reduced after WBV (-5.7%, p = 0.004) and HSR (-3.0%, p = 0.004) training compared to WLC although the equivalence test between interventions was inconclusive. Conclusion: Whole body vibration improved symptoms typically associated with patellar tendinopathy. This type of intervention is as effective as HSR against maximum pain, although equivalence could not be confirmed for other variables. The beneficial responses to WBV and HSR treatments persisted for 6 months after the end of the intervention. Clinical Trial Registration: https://www.drks.de/drks_web/setLocale_EN.do, identifier DRKS00011338.

Specificity of eccentric hamstring training and the lack of consistency between strength assessments using conventional test devices.

Hamstring injuries are endemic, but influences of test-specific training and the application of different test methods on decision making remain elusive. Sport-students were randomised to isokinetic (IG) or Nordic hamstring (NG) exercise or a control group (CG) for six weeks. Training and testing procedures were matched to biomechanical parameters. Hamstring strength (EPT), work, muscle soreness (visual analogue scale (VAS)), biceps femoris (BFlh) muscle size and architecture were assessed. Anthropometrics and strength parameters did not differ at baseline. Yet, body mass normalised EPT, and work revealed a significant group × time × device effect, with a significant main effect for devices. Experimental conditions triggered meaningful increases in EPT compared to the control group, but the effects were higher when recorded on the training device. Despite significant group × time interactions, normalised average work on the NHD was only higher in the NG compared to CG of the left leg (+ 35%). No effects were found for BFlh parameters. Hamstrings showed a high training specificity, but adaptations likely remain undetected owing to the low sensitivity of conventional test devices. Moreover, strength increase of ~ 15% does not necessarily have to be reflected in BFlh parameters.

Mechanical and Material Tendon Properties in Patients With Proximal Patellar Tendinopathy.

INTRODUCTION: The effect of chronic patellar tendinopathy on tissue function and integrity is currently unclear and underinvestigated. The aim of this cohort comparison was to examine morphological, material, and mechanical properties of the patellar tendon and to extend earlier findings by measuring the ability to store and return elastic energy in symptomatic tendons. METHODS: Seventeen patients with chronic (>3 months, VISA-P < 80), inferior pole patellar tendinopathy (24 ± 4 years; male = 12, female = 5) were carefully matched to controls (25 ± 3 years) for training status, pattern, and history of loading of the patellar tendon. Individual knee extension force, patellar tendon stiffness, stress, strain, Young's modulus, hysteresis, and energy storage capacity, were obtained with combined dynamometry, ultrasonography, magnetic resonance imaging, and electromyography. RESULTS: Anthropometric parameters did not differ between groups. VISA-P scores ranged from 28 to 78 points, and symptoms had lasted from 10 to 120 months before testing. Tendon proximal cross-sectional area was 61% larger in the patellar tendinopathy group than in the control group. There were no differences between groups in maximal voluntary isometric knee extension torque (p = 0.216; d < -0.31) nor in tensile tendon force produced during isometric ramp contractions (p = 0.185; d < -0.34). Similarly, tendon strain (p = 0.634; d < 0.12), hysteresis (p = 0.461; d < 0.18), and strain energy storage (p = 0.656; d < 0.36) did not differ between groups. However, patellar tendon stiffness (-19%; p = 0.007; d < -0.74), stress (-27%; p< 0.002; d < -0.90) and Young's modulus (-32%; p = 0.001; d < -0.94) were significantly lower in tendinopathic patients compared to healthy controls. DISCUSSION: In this study, we observed lower stiffness in affected tendons. However, despite the substantial structural and histological changes occurring with tendinopathy, the tendon capacity to store and dissipate energy did not differ significantly.

Quantitative Analysis of Patellar Tendon After Total Knee Arthroplasty Using Echo Intensity: A Nonrandomized Controlled Trial of Alpine Skiing.

BACKGROUND: Despite the knee extensor weakness, less attention has been paid to the evaluation of patellar tendon after total knee arthroplasty (TKA). We previously observed patellar tendon hypertrophy after TKA. The purpose of this study is to reanalyze these ultrasound data to detect whether brightness mode ultrasound imaging reflects pathological changes of the patellar tendon after TKA. METHODS: Twenty-eight participants with post unilateral TKA were assigned to an intervention group or control group. The intervention group underwent a 12-week skiing program. Patellar tendon mechanical properties were obtained by combining isometric dynamometry, ultrasound imaging, and electromyography in operated knee and nonoperated knee. Luminosity ratio (LR) was measured using echo intensity in a relaxed and maximally loaded phase. RESULTS: Baseline comparisons revealed significant effects of the surgical side (P < .001) and loading phase (P = .017), but no interaction between leg and phase (P < .149). LR of the operated knee was significantly lower than LR of the nonoperated knee in relaxed (P < .001) and maximally loaded phases (P = .003). In addition, there was a significant correlation between LR of maximum phase and isometric knee extension torque (r2 = 0.156, P = .038). However, LR was not related to patellar tendon stiffness, Young's modulus, or strain. There was a significant time effect in knee extension torque, but no time effects on LR and tendon force. CONCLUSION: Patellar tendon LR is decreased along with degenerative change after TKA. Ultrasound imaging provides a promising metric to acquire in vivo patellar tendon pathological assessment after TKA.

Device and method matter: A critical evaluation of eccentric hamstring muscle strength assessments.

Equivocal findings exist on isokinetic and Nordic hamstring exercise testing of eccentric hamstring strength capacity. Here, we propose a critical comparison of the mechanical output of hamstring muscles as assessed with either a dynamometer (IKD) or a Nordic hamstring device (NHD). Twenty-five volunteers (26 ± 3 years) took part in a counterbalanced repeated-measures protocol on both devices. Eccentric peak torque, work, angle of peak torque, bilateral strength ratios, and electromyography activity of the biceps femoris long head, semitendinosus and gastrocnemius muscles were assessed. There was a very poor correlation in eccentric peak torque between the devices (r < 0.58), with a systematic and proportional bias toward lower torque values on the IKD (~28%) and a high typical error (~19%) in IKD and NHD measurements comparison. Furthermore, participants performed a higher total eccentric work on IKD, reached peak torques at greater knee extension angles, and showed a greater side-to-side strength difference compared to the Nordic hamstring exercise. Gastrocnemius muscle activity was lower during the Nordic hamstring exercise. Reliability was low for work on NHD and for angle of peak torque and bilateral strength ratios on either device. We conclude that the evaluation of eccentric knee flexor strength depends on the testing conditions and even under standardized procedures, the IKD and NHD measure a different trait. Both tests have limitations in terms of assessing strength differences within an individual, and measurements of the angle of peak torque or side-to-side differences in eccentric knee flexor strength revealed low reliability and should be considered with caution.

Aging in high functioning elderly persons: study design and analyses of behavioral and psychological factors.

This article aims to (a) describe the study design of a 6-year follow-up multidisciplinary research project on aging, (b) report the psychosocial characteristics of the sample in detail, and (c) evaluate aging-related changes of health, physical activity, and psychosocial characteristics in 10 young-old (age at pre-test: M ± SD = 63.2 ± 1.5) and 12 old-old (age at pre-test: M ± SD = 69 ± 2) individuals. Both age groups consist of individuals displaying a high health status, a high extent of physical activity, high levels of psychosocial properties in the dimensions of well-being, life satisfaction, self-concept, body image, self-esteem, and self-efficacy, as well as a low general depression index. Psychosocial characteristics demonstrated a stable pattern over a period of nearly 6 years in both age groups with the exceptions of physical activity, satisfaction with children, general depression, and self-efficacy. Furthermore, physical self-concept decreased in old-old adults, whereas the young-olds showed no change. We assume that a high psychosocial status and a physically active lifestyle play an important role for mastering aging successfully in two life phases, each of which has its own challenges for older individuals. The decline in the physical self-concept of old-olds is interpreted as a first sign of subjective aging. Its association with losses in physical performance should be addressed in future studies. Finally, aging-related changes should be monitored on an individual level in order to capture the complex dynamic of aging that is not considered in analyses of between-person differences or averages.

Effect of aging on muscle and tendon properties in highly functioning elderly people.

This study analyzes long-term changes in muscle strength, muscle architecture, and patellar tendon mechanical properties in a specific sample of physically active elderly people. Twenty-two participants were re-examined from a former 12-week-long skiing intervention study: 11 from the intervention group (IG: 7 ♀, 4 ♂; 67 ± 3 years) and 11 from the control group (CG: 6 ♀, 5 ♂; 66 ± 4 years). Muscle architecture, strength endurance, maximum torque, and tendon properties were analyzed three times within 6 months, and again 6 years later in a follow-up test. No changes in either group could be observed between June 2009 and April 2015 in any parameter. This can be interpreted positively because no age-related decreases were found. Although our participants were physically active from the very beginning (>150 min/wk), it must be noted that the intensity of the physical activity was too low to provoke physiological improvements in leg strength or muscle/tendon morphology.

Sport-Specific Capacity to Use Elastic Energy in the Patellar and Achilles Tendons of Elite Athletes.

Introduction: During running and jumping activities, elastic energy is utilized to enhance muscle mechanical output and efficiency. However, training-induced variations in tendon spring-like properties remain under-investigated. The present work extends earlier findings on sport-specific profiles of tendon stiffness and cross-sectional area to examine whether years of distinct loading patterns are reflected by tendons' ability to store and return energy. Methods:Ultrasound scans were performed to examine the morphological features of knee extensor and plantar flexor muscle-tendon units in elite ski jumpers, distance runners, water polo players, and sedentary controls. Tendon strain energy and hysteresis were measured with combined motion capture, ultrasonography, and dynamometry. Results: Apart from the fractional muscle-to-tendon cross-sectional area ratio being lower in the knee extensors of ski jumpers (-31%) and runners (-33%) than in water polo players, no difference in the considered muscle-tendon unit morphological features was observed between groups. Similarly, no significant difference in tendon energy storage or energy return was detected between groups. In contrast, hysteresis was lower in the patellar tendon of ski jumpers (-33%) and runners (-30%) compared to controls, with a similar trend for the Achilles tendon (significant interaction effect and large effect sizes η2 = 0.2). Normalized to body mass, the recovered strain energy of the patellar tendon was ~50% higher in ski jumpers than in water polo players and controls. For the Achilles tendon, recovered strain energy was ~40% higher in ski jumpers and runners than in controls. Discussion: Advantageous mechanical properties related to tendon spring-like function are observed in elite athletes whose sport require effective utilization of elastic energy. However, the mechanisms underpinning the better tendon capacity of some athletes to retain elastic energy could not be ascribed to intrinsic or morphological features of the lower limb muscle-tendon unit.

Are Sport-Specific Profiles of Tendon Stiffness and Cross-Sectional Area Determined by Structural or Functional Integrity?

The present study aimed to determine whether distinct sets of tendon properties are seen in athletes engaged in sports with contrasting requirements for tendon function and structural integrity. Patellar and Achilles tendon morphology and force-deformation relation were measured by combining ultrasonography, electromyography and dynamometry in elite ski jumpers, distance runners, water polo players and sedentary individuals. Tendon cross-sectional area normalized to body mass2/3 was smaller in water polo players than in other athletes (patellar and Achilles tendon; -28 to -24%) or controls (patellar tendon only; -9%). In contrast, the normalized cross-sectional area was larger in runners (patellar tendon only; +26%) and ski jumpers (patellar and Achilles tendon; +21% and +13%, respectively) than in controls. Tendon stiffness normalized to body mass2/3 only differed in ski jumpers, compared to controls (patellar and Achilles tendon; +11% and +27%, respectively) and to water polo players (Achilles tendon only; +23%). Tendon size appears as an adjusting variable to changes in loading volume and/or intensity, possibly to preserve ultimate strength or fatigue resistance. However, uncoupled morphological and mechanical properties indicate that functional requirements may also influence tendon adaptations.

Explosive Strength of the Knee Extensors: The Influence of Criterion Trial Detection Methodology on Measurement Reproducibility.

The present study was conducted to assess test-retest reproducibility of explosive strength measurements during single-joint isometric knee extension using the IsoMed 2000 dynamometer. Thirty-one physically active male subjects (mean age: 23.7 years) were measured on two occasions separated by 48-72 h. The intraclass correlation coefficient (ICC 2,1) and the coefficient of variation (CV) were calculated for (i) maximum torque (MVC), (ii) the peak rate of torque development (RTDpeak) as well as for (iii) the average rate of torque development (RTD) and the impulse taken at several predefined time intervals (0-30 to 0-300 ms); thereby explosive strength variables were derived in two conceptually different versions: on the one hand from the MVC-trial (version I), on the other hand from the trial showing the RTDpeak (version II). High ICC-values (0.80-0.99) and acceptable CV-values (1.9-8.7%) could be found for MVC as well as for the RTD and the impulse taken at time intervals of ≥100 ms, regardless of whether version I or II was used. In contrast, measurements of the RTDpeak as well as the RTD and the impulse taken during the very early contraction phase (i.e. RTD/impulse0-30ms and RTD/impulse0-50ms) showed clearly weaker reproducibility results (ICC: 0.53-0.84; CV: 7.3-16.4%) and gave rise to considerable doubts as to clinical usefulness, especially when derived using version I. However, if there is a need to measure explosive strength for earlier time intervals in practice, it is, in view of stronger reproducibility results, recommended to concentrate on measures derived from version II, which is based on the RTDpeak-trial.

Effects of Increased Loading on In Vivo Tendon Properties: A Systematic Review.

INTRODUCTION: In vivo measurements have been used in the past two decades to investigate the effects of increased loading on tendon properties, yet the current understanding of tendon macroscopic changes to training is rather fragmented, limited to reports of tendon stiffening, supported by changes in material properties and/or tendon hypertrophy. The main aim of this review was to analyze the existing literature to gain further insights into tendon adaptations by extracting patterns of dose-response and time-course. METHODS: PubMed/Medline, SPORTDiscus, and Google Scholar databases were searched for studies examining the effect of training on material, mechanical, and morphological properties via longitudinal or cross-sectional designs. RESULTS: Thirty-five of 6440 peer-reviewed articles met the inclusion criteria. The key findings were i) the confirmation of a nearly systematic adaptation of tendon tissue to training, ii) the important variability in the observed changes in tendon properties between and within studies, and iii) the absence of a consistent incremental pattern regarding the dose-response or the time-course relation of tendon adaptation within the first months of training. However, long-term (years) training was associated with a larger tendon cross-sectional area, without any evidence of differences in material properties. Our analysis also highlighted several gaps in the existing literature, which may be addressed in future research. CONCLUSIONS: In line with some cross-species observations about tendon design, tendon cross-sectional area allegedly constitutes the ultimate adjusting parameter to increased loading. We propose here a theoretical model placing tendon hypertrophy and adjustments in material properties as parts of the same adaptive continuum.

[Dynamic and static maximum strength in closed kinetic chain movements. Trunkflexion/-extension and -rotation]. / Dynamische und statische Maximalkraft in der geschlossenen Kette bei Rumpfflexion/-extension und Rumpfrotation.

BACKGROUND: Isokinetics offer a range of applications in hospital, therapy and training. The aim of this study was to determine, how the torques (Nm) of trunk flexion/-extension and trunk rotation behave at different contraction types (eccentrically, isometrically, concentrically) and different speeds. METHOD: Therefore different isokinetic testing procedures were performed in 34 subjects (17 female). RESULTS: The angle (°) in which the max. torque (Nm) is measured is inconsistent for the trunk flexion. Here the maximum values for different contraction forms and speeds of movement were found between +1,73 and -19,24°. For extension, however, the max values were achieved between +6,12 and +17,42° (hip angle < 90°). For trunk rotation the highest values were found, when the torso was rotated to the opposite side of the movement. For example, at left rotation the maximum values were found between -12,91 and -18,97°. As a recommendation for the test speed 30°/sec. is stated for both movements concentric and eccentric, since these data have a high accuracy (best interpretation) and this speed was felt to be pleasant. The highest torques were usually measured at 30°/sec. eccentric, predominant values for 15°/sec. eccentric and isometric were significantly lower. CONCLUSION: These results should contribute to an efficient application of the IsoMed 2000 testing and training device in clinical, therapeutical and sport scientific fields.