Structure and function of Achilles and patellar tendons following moderate slow resistance training in young and old men.

The aim of this study was to investigate the effect of aging and resistance training with a moderate load on the size and mechanical properties of the patellar (PT) and Achilles tendon (AT) and their associated aponeuroses; medial gastrocnemius (MG) and vastus lateralis (VL). Young (Y55; 24.8 ± 3.8 yrs, n = 11) and old men (O55; 70.0 ± 4.6 yrs, n = 13) were assigned to undergo a training program (12 weeks; 3 times/week) of moderate slow resistance training [55% of one repetition maximum (RM)] of the triceps surae and quadriceps muscles. Tendon dimensions were assessed using 1.5 T magnetic resonance imaging before and after 12 weeks. AT and PT cross sectional area (CSA) were determined every 10% of tendon length. Mechanical properties of the free AT, MG aponeurosis, PT, and VL aponeurosis were assessed using ultrasonography (deformation) and tendon force measurements. CSA of the AT but not PT was greater in O55 compared with Y55. At baseline, mechanical properties were generally lower in O55 than Y55 for AT, MG aponeurosis and VL aponeurosis (Young's modulus) but not for PT. CSA of the AT and PT increased equally in both groups following training. Further, for a given force, stiffness and Young's modulus also increased equally for VL aponeurosis and AT, for boths groups. The present study highlights that except for the PT, older men have lower tendon (AT, MG aponeurosis, and VL aponeurosis) mechanical properties than young men and 12-weeks of moderate slow resistance training appears sufficient to improve tendon size and mechanical adaptations in both young and older men. New and Noteworthy: These novel findings suggest that short-term moderate slow resistance training induces equal improvements in tendon size and mechanics regardless of age.

Data driven model of midportion achilles tendinopathy health created with factor analysis.

BACKGROUND: Achilles tendinopathy is a complex injury and the clinical presentation spans multiple different domains: physical and psychological symptoms, lower extremity function and tendon structure. A conceptual model of Achilles tendon health comprising these domains has been proposed in the literature. The aim of the study was to fit a model of Achilles tendinopathy using factor analysis and compare that to the conceptual model. An inclusive approach using a wide range of variables spanning multiple potential domains were included. METHODS: Participants (N = 99) with midportion Achilles tendinopathy were assessed with variables representing symptoms, physical function, tendon structure, metabolic syndrome, and psychologic symptoms. A Kaiser-Mayer-Olkin index was used to determine suitable variables for a subsequent exploratory factor analysis. RESULTS: A model emerged with an acceptable fit to the data (standardized root mean square of residuals = 0.078). Five uncorrelated factors emerged from the model and were labelled as biopsychosocial, lower extremity function, body size, load tolerance, and tendon structure. The total explained variance was 0.51 with the five factors explaining 0.14, 0.12, 0.10, 0.08, and 0.07 respectively. The results differed from the conceptual model as the factors of psychological variables and metabolic variables did not emerge from the analysis. CONCLUSION: A data driven model of Achilles tendon health supports assessment of the clinical presentation over multiple domains. As the factors are uncorrelated, the results of assessment of, for example, tendon structure should not be expected to be associated with lower extremity function or biopsychosocial limitations. The results suggest that the Patient Reported Outcomes Measurement Information System, counter-movement jump height, body mass index, pain with hopping, and the tendon cross-sectional area can evaluate the five factors, respectively. TRIAL REGISTRATION: Registered on clinicaltrials.gov (Medicine NL of. CLINICALTRIALS: gov [Internet], 2018), ID number NCT03523325.

Early development of tendinopathy in humans: Sequence of pathological changes in structure and tissue turnover signaling.

Overloading of tendon tissue with resulting chronic pain (tendinopathy) is a common disorder in occupational-, leisure- and sports-activity, but its pathogenesis remains poorly understood. To investigate the very early phase of tendinopathy, Achilles and patellar tendons were investigated in 200 physically active patients and 50 healthy control persons. Patients were divided into three groups: symptoms for 0-1 months (T1), 1-2 months (T2) or 2-3 months (T3). Tendinopathic Achilles tendon cross-sectional area determined by ultrasonography (US) was ~25% larger than in healthy control persons. Both Achilles and patellar anterior-posterior diameter were elevated in tendinopathy, and only later in Achilles was the width increased. Increased tendon size was accompanied by an increase in hypervascularization (US Doppler flow) without any change in mRNA for angiogenic factors. From patellar biopsies taken bilaterally, mRNA for most growth factors and tendon components remained unchanged (except for TGF-beta1 and substance-P) in early tendinopathy. Tendon stiffness remained unaltered over the first three months of tendinopathy and was similar to the asymptomatic contra-lateral tendon. In conclusion, this suggests that tendinopathy pathogenesis represents a disturbed tissue homeostasis with fluid accumulation. The disturbance is likely induced by repeated mechanical overloading rather than a partial rupture of the tendon.

Mechanical properties and UTE-T2* in Patellar tendinopathy: The effect of load magnitude in exercise-based treatment.

Loading intervention is currently the preferred management of tendinopathy, but to what extent different loading regimes influence the mechanical response in tendons is scarcely investigated. Therefore, the purposes of the investigation were to examine the effect of exercise interventions with either high or low load magnitude applied to the tendinopathic patellar tendon and the influence on its mechanical, material, and morphological properties. Forty-four men with chronic patellar tendinopathy were randomized to 12 weeks of exercising with either; 55% of 1RM throughout the period (MSR group) or 90% of 1RM (HSR group), and with equal total exercise volume in both groups. Mechanical (stiffness), material (T2* relaxation time), and morphological (cross-sectional area (CSA)) properties were assessed at baseline and after 12 weeks of intervention. MRI with ultra-short echo times (UTE) and T2*-mapping was applied to explore if T2* relaxation time could be used as a noninvasive marker for internal material alteration and early change thereof in response to intervention. There was no effect of HSR or MSR on the mechanical (stiffness), material (T2* relaxation time) or morphological (CSA) properties, but both regimes resulted in significant strength gain. In conclusion, there were no statistically superior effect of exercising with high (90%) compared to moderate (55%) load magnitude on the mechanical, material or morphological properties.

Chronic hyperglycemia, hypercholesterolemia, and metabolic syndrome are associated with risk of tendon injury.

Tendon injury is a considerable problem affecting both physically active and sedentary people. The aim of this study was to examine the relationship between markers for metabolic disorders (hyperglycemia, hypercholesterolemia, and metabolic syndrome) and the risk of developing tendon injuries requiring referral to a hospital. The Copenhagen City Heart Study is a prospective study of diabetic and non-diabetic individuals from the Danish general population with different physical activity levels. The cohort was followed for 3 years via national registers with respect to tendon injuries. Data from 5856 individuals (median age 62 years) were included. The overall incidence of tendon injury in both upper and lower extremities that required an out-patient or in-house visit to a hospital was ~5.7/1000 person years. Individuals with elevated HbA1c (glycated hemoglobin) even in the prediabetic range (HbA1c>5.7%) had a ~3 times higher risk of tendon injury in the lower extremities only, as compared to individuals with normal HbA1C levels. Hypercholesterolemia (total cholesterol>5 mmol/L) increased risk of tendon injury in the upper extremities by ~1.5 times, and individuals with metabolic syndrome had ~2.5 times higher risk of tendon injury in both upper and lower extremities. In conclusion, these data demonstrate for the first time in a large cohort with different physical activity levels that the indicators for metabolic syndrome are a powerful systemic determinant of tendon injury, and two of its components, hyperglycemia and hypercholesterolemia, each independently make tendons susceptible for damage and injury.

Muscles adaptation to aging and training: architectural changes - a randomised trial.

BACKGROUND: To investigate how anatomical cross-sectional area and volume of quadriceps and triceps surae muscles were affected by ageing, and by resistance training in older and younger men, in vivo. METHODS: The old participants were randomly assigned to moderate (O55, n = 13) or high-load (O80, n = 14) resistance training intervention (12 weeks; 3 times/week) corresponding to 55% or 80% of one repetition maximum, respectively. Young men (Y55, n = 11) were assigned to the moderate-intensity strengthening exercise program. Each group received the exact same training volume on triceps surae and quadriceps group (Reps x Sets x Intensity). The fitting polynomial regression equations for each of anatomical cross-sectional area-muscle length curves were used to calculate muscle volume (contractile content) before and after 12 weeks using magnetic resonance imaging scans. RESULTS: Only Rectus femoris and medial gastrocnemius muscle showed a higher relative anatomical cross-sectional area in the young than the elderly on the proximal end. The old group displayed a higher absolute volume of non-contractile material than young men in triceps surae (+ 96%). After training, Y55, O55 and O80 showed an increase in total quadriceps (+ 4.3%; + 6.7%; 4.2% respectively) and triceps surae (+ 2.8%; + 7.5%; 4.3% respectively) volume. O55 demonstrated a greater increase on average gains compared to Y55, while no difference between O55 and O80 was observed. CONCLUSIONS: Muscle loss with aging is region-specific for some muscles and uniform for others. Equivalent strength training volume at moderate or high intensities increased muscle volume with no differences in muscle volume gains for old men. These data suggest that physical exercise at moderate intensity (55 to 60% of one repetition maximum) can reverse the aging related loss of muscle mass. TRIAL REGISTRATION: NCT03079180 in ClinicalTrials.gov . Registration date: March 14, 2017.

Regional differences in turnover, composition, and mechanics of the porcine flexor tendon.

PURPOSE: Recent data suggest that there is a lack of turnover in the core of human tendon, but it remains unknown whether there are regional differences between core and periphery of the cross section. The purpose of this project was to investigate regional differences in turnover as estimated by the accumulation of fluorescent Advanced Glycation End-products (AGEs) and regional differences in mechanical properties. MATERIALS AND METHODS: Tendons were obtained from lean control (n = 4) and diabetic Göttingen minipigs (streptozotocin-induced, n = 6). The deep digital flexor tendon of one hind limb was separated into a proximal, central and distal part. Autofluorescence was measured in the core and periphery of the proximal and distal parts of the tendon, and mechanical properties were tested on fascicles taken from the core and periphery of the central tendon (only diabetic animals). RESULTS: Autofluorescence was greater in the proximal than the distal part. In the distal part of the lean control animals, autofluorescent AGE accumulation was also greater in the core than the periphery. Peak modulus in the core region (704 ± 79 MPa) was higher than the periphery (466 ± 53 MPa, p < 0.05) in diabetic tendons. CONCLUSION: Taken together, autofluorescence varied both along the length and across the tendon cross section, indicating higher turnover in the distal and peripheral regions. In addition, mechanical properties differed across the tendon cross-section.

Ultrasound speckle tracking of Achilles tendon in individuals with unilateral tendinopathy: a pilot study.

PURPOSE: Differential displacement between tendon layers has been shown to occur within the healthy Achilles tendon, and changes of this mechanism have been proposed to result in shear forces, which potentially could lead to tendinopathy. The magnitude of displacement between the tendon layers in tendinopathy is unknown. The purpose of this study was to investigate Achilles tendon layer displacement in individuals suffering from unilateral tendinopathy compared with the asymptomatic contralateral side. METHODS: Ten participants (9 men and 1 woman 45 ± 10 years, BMI: 28 ± 5) with unilateral Achilles tendinopathy were included. Intra-tendinous motion was assessed using ultrasonography during dynamic unilateral heel rises in standing and seated position. Speckle displacement was determined using a cross-correlation algorithm, in four independent rows, representing superficial and deep tendon layers. RESULTS: The most superficial layer displaced less than the deepest in all condition, except standing for the tendinopathic leg. There was a strong tendency (p = 0.054) for the displacement difference being reduced in the tendinopathic tendon (Tendinopathic side: 0.52 ± 0.16 mm vs. asymptomatic contralateral side: 1.02 ± 0.18 mm). CONCLUSION: These novel data suggest that the presence of tendinopathy diminishes intra-tendinous sliding in the Achilles tendon.

Heterotopic Ossification After an Achilles Tendon Rupture Cannot Be Prevented by Early Functional Rehabilitation: A Cohort Study.

BACKGROUND: Tendon loading might play a role in the development of heterotopic ossification after Achilles tendon ruptures. Early heavy loading on a healing tendon in animals has been shown to prolong the proinflammatory response, and inflammatory cells are thought to drive heterotopic ossification formation. Taken together, this suggests that early rehabilitation might influence heterotopic ossification development. QUESTIONS/PURPOSES: The purposes of this study were to investigate (1) whether the presence of heterotopic ossification after Achilles tendon ruptures influences clinical outcome and (2) whether early mobilization or weightbearing prevents the development of heterotopic ossification. METHODS: This was a retrospective analysis of 69 patients from a previous clinical trial. All patients were treated surgically, but with three different early rehabilitation protocols after surgery: late weightbearing and ankle immobilization, late weightbearing and ankle mobilization, and early weightbearing and ankle mobilization. Plain radiographs taken 2, 6, 12, 26, and 52 weeks postoperatively were analyzed for heterotopic ossification, which was detected in 19% of patients (13 of 69) at 52 weeks. Heterotopic ossification was measured, scored, and correlated to clinical outcomes; heel-raise index (HRI), ankle joint ROM, tendon strain, Achilles tendon rupture score (ATRS), and Victorian Institute of Sport Assessment-Achilles (VISA-A) questionnaire scores at 26 and 52 weeks postoperatively. RESULTS: Heterotopic ossification had no adverse effects on patient-reported outcomes (ATRS or VISA-A), tendon strain, or ROM. In fact, patients with heterotopic ossification tended to have a better HRI at 52 weeks compared with patients without (mean difference 14% [95% CI -0.2 to 27]; p = 0.053). Neither the occurrence (heterotopic ossification/no heterotopic ossification) nor the heterotopic ossification severity (ossification score) differed between the three rehabilitation groups. Seventeen percent of the patients (four of 24) with early functional rehabilitation (early weightbearing and ankle joint mobilization exercise) had heterotopic ossification (score, 2-3) while late weightbearing and immobilization resulted in heterotopic ossification in 13% of the patients (score, 3-4). CONCLUSIONS: Heterotopic ossification occurs relatively frequently after Achilles tendon ruptures but appears to have no adverse effects on functional outcomes. Furthermore, heterotopic ossification develops during the first 6 weeks after rupture, and weightbearing or ankle-joint mobilization does not prevent this from occurring. LEVEL OF EVIDENCE: Level III, prognostic study.

Load magnitude affects patellar tendon mechanical properties but not collagen or collagen cross-linking after long-term strength training in older adults.

BACKGROUND: Regular loading of tendons may counteract the negative effects of aging. However, the influence of strength training loading magnitude on tendon mechanical properties and its relation to matrix collagen content and collagen cross-linking is sparsely described in older adults. The purpose of the present study was to compare the effects of moderate or high load resistance training on tendon matrix and its mechanical properties. METHODS: Seventeen women and 19 men, age 62-70 years, were recruited and randomly allocated to 12 months of heavy load resistance training (HRT), moderate load resistance training (MRT) or control (CON). Pre- and post-intervention testing comprised isometric quadriceps strength test (IsoMVC), ultrasound based testing of in vivo patellar tendon (PT) mechanical properties, MRI-based measurement of PT cross-sectional area (CSA), PT biopsies for assessment of fibril morphology, collagen content, enzymatic cross-links, and tendon fluorescence as a measure of advanced glycation end-products (AGEs). RESULTS: Thirty three participants completed the intervention and were included in the data analysis. IsoMVC increased more after HRT (+ 21%) than MRT (+ 8%) and CON (+ 7%) (p < 0.05). Tendon stiffness (p < 0.05) and Young's modulus (p = 0.05) were also differently affected by training load with a reduction in CON and MRT but not in HRT. PT-CSA increased equally after both MRT and HRT. Collagen content, fibril morphology, enzymatic cross-links, and tendon fluorescence were unaffected by training. CONCLUSION: Despite equal improvements in tendon size after moderate and heavy load resistance training, only heavy. load training seemed to maintain tendon mechanical properties in old age. The effect of load magnitude on tendon biomechanics was unrelated to changes of major load bearing matrix components in the tendon core. The study is a sub-study of the LISA study, which was registered at http://clinicaltrials.gov (NCT02123641) April 25th 2014.

Role of tissue perfusion, muscle strength recovery, and pain in rehabilitation after acute muscle strain injury: A randomized controlled trial comparing early and delayed rehabilitation.

Muscle strain injuries disrupt the muscle-tendon unit, early rehabilitation is associated with a faster return to sports (RTS), but the time course of tissue healing remains sparsely described. The purpose was to examine tissue regeneration and the effectiveness of early versus delayed rehabilitation onset on functional and structural recovery after strain injuries. A total of 50 recreational athletes with a severe acute strain injury in their thigh or calf muscles were randomized to early or delayed rehabilitation onset. Magnetic resonance imaging (MRI) was obtained initially, 3 and 6 months postinjury, and dynamic contrast-enhanced MRI (DCE-MRI) estimated tissue inflammation initially and after 6 months. Muscle strength was determined 5 weeks, 3 months, and 6 months postinjury, and a questionnaire determined soreness, pain, and confidence. DCE-MRI microvascular perfusion was higher in the injured compared to an uninjured muscle acutely (P < 0.01) and after 6 months (P < 0.01), for both groups (P > 0.05) and unrelated to RTS (P > 0.05). Total volume of the injured muscle decreased from the acute to the 3-month scan, and to the 6-month scan (P < 0.01) in both groups. Muscle strength was similar in both groups at any time. There was a nonsignificant trend (P ≤ 0.1) toward less pain and higher confidence with early rehabilitation. One reinjury was recorded. In conclusion, our data showed prolonged tissue repair with the initial response linked to muscle atrophy but did not explain why early rehabilitation onset accelerated recovery considering that structural and functional recovery was similar with early and delayed rehabilitation.

Biomechanical properties of the patellar tendon in children with heritable connective tissue disorders.

PURPOSE: Hereditary connective tissue disorders (HCTDs), such as classic Ehlers-Danlos syndrome (cEDS) and Marfan syndrome (MS) share overlapping features like hypermobility and tissue fragility. In clinical practice it remains a challenge to distinguish children and adolescents with HCTD from healthy children. The purpose of this study was to investigate the biomechanical properties of the patellar tendon and joint laxity (Beighton score) in children with HCTDs (n = 7) compared to healthy controls (n = 14). METHODS: The mechanical properties of the patellar tendon were assessed using simultaneous force and ultrasonographic measurements during isometric ramp contractions. Ultrasonography was also used to measure tendon dimensions. The HCTD children were matched with 2 healthy controls with regard to age, body mass index (BMI), sex and physical activity level. RESULTS: The HCTD children had a greater degree of joint laxity (P < 0.01). Although, the patellar tendon dimensions did not differ significantly between the two groups, the HCTD children showed a tendency toward a larger patellar tendon cross-sectional area (CSA) (35%, P = 0.19). Moreover, stiffness did not differ between the two groups, but secant modulus was 27% lower in children with a HCTD (P = 0.05) at common force and 34% lower at maximum force (P = 0.02). CONCLUSIONS: The present study demonstrates for the first time that children with HCTDs have lower material properties (modulus) of their patellar tendon, which may be indicative of general impairment of connective tissue mechanics related to their increased joint laxity.

Quantification of cell density in rat Achilles tendon: development and application of a new method.

Increased tendon cell nuclei density (TCND) has been proposed to induce tendon mechanical adaptations. However, it is unknown whether TCND is increased in tendon tissue after mechanical loading and whether such an increase can be quantified in a reliable manner. The aim of this study was to develop a reliable method for quantification of TCND and to investigate potential changes in TCND in rat Achilles tendons in response to 12 weeks of running. Eight adult male Sprague-Dawley rats ran (RUN) on a treadmill with 10° incline, 1 h/day, 5 days/wk (17-20 m/min) for 12 weeks (which improved tendon mechanical properties) and were compared with 11 control rats (SED). Tissue-Tek-embedded cryosections (10 µm) from the mid region of the Achilles tendon were cut longitudinally on a cryostat. Sections were stained with alcian blue and picrosirius red. One blinded investigator counted the number of tendon cell nuclei 2-3 times in three separate regions of the mid longitudinal tendon sections with fields of 390 µm × 280 µm. Unpaired t tests were used for the statistical analysis (mean ± SE). Typical Error % for replicate counts was 5.5 and 14 % coefficient of variation for the three regions. There was no difference in TCND between running rats versus control rats (nuclei per image (≈105 µm2): RUN, 152 ± 9; SED, 146 ± 8, p = 0.642). This new method provided reproducible quantification of TCND. There was no difference in TCND despite improvements in tendon mechanics, which suggests that cell number is not a major cause for altered tendon mechanical properties with loading.

Ruptured human Achilles tendon has elevated metabolic activity up to 1 year after repair.

PURPOSE: Following Achilles tendon rupture, running is often allowed after 6 months. However, tendon healing is slow and the metabolic status of the tendon at this point is unknown. The purpose of this study was to investigate tendon metabolism (glucose uptake) and vascularization at 3, 6 and 12 months after Achilles tendon rupture as measured using PET and power Doppler ultrasonography (PDUS). METHODS: The study group comprised 23 patients with surgically repaired Achilles tendon rupture who were investigated at 3 months (n = 7), 6 months (n = 7) and 12 months (n = 9) after surgery. The triceps surae complex was loaded over 20 min of slow treadmill walking while a radioactive tracer ((18)F-FDG) was administered prior to PET. Vascularization was measured in terms of PDUS flow activity, and patient-reported outcomes were scored using the Achilles tendon rupture score (ATRS) and sports assessment (VISA-A) questionnaire. RESULTS: Relative glucose uptake ((18)F-FDG) was higher in repaired tendons than in intact tendons at all time-points (6, 3 and 1.6 times higher at 3, 6 and 12 months, respectively; P ≤ 0.001), and was also higher in the tendon core than in the periphery at 3 and 6 months (P ≤ 0.02), but lower at 12 months (P = 0.06). Relative glucose uptake was negatively related to ATRS at 6 months after repair (r = -0.89, P ≤ 0.01). PDUS flow activity was higher in repaired tendons than in intact tendons at 3 and 6 months (P < 0.05 for both), but had normalized by 12 months. CONCLUSION: These data demonstrate that the healing process as determined by metabolic activity and vascularization continues for 6 months after injury when large loads are typically allowed on the tendon. Indeed, metabolic activity remained elevated for more than 1 year after injury despite normalized vascularization. The robust negative correlation between tendon metabolism and patient-reported outcome suggests that a high metabolic activity 6 months after the injury may be related to a poor clinical healing outcome.

Low tendon stiffness and abnormal ultrastructure distinguish classic Ehlers-Danlos syndrome from benign joint hypermobility syndrome in patients.

There is a clinical overlap between classic Ehlers-Danlos syndrome (cEDS) and benign joint hypermobility syndrome (BJHS), with hypermobility as the main symptom. The purpose of this study was to investigate the role of type V collagen mutations and tendon pathology in these 2 syndromes. In patients (cEDS, n=7; BJHS, n=8) and controls (Ctrl, n=8), we measured patellar tendon ultrastructure (transmission electron microscopy), dimensions (magnetic resonance imaging), and biomechanical properties (force and ultrasonographic measurements during a ramped isometric knee extension). Mutation analyses (COL5A1 and COL5A2) were performed in the patients. COL5A1 mutations were found in 3 of 4 of the patients with cEDS. Patellar tendon dimensions were similar between the groups, but large, irregular collagen fibrils were in 4 of 5 patients with cEDS. In the cEDS group, tendon stiffness and Young's modulus were reduced to ∼50% of that in BJHS and Ctrl groups (P<0.05). The nonhypermobile, healthy controls were matched with the patients in age, sex, body weight, and physical activity, to compare outcomes. COL5A1 mutations led to structural tendon pathology and low tendon stiffness in cEDS, explaining the patients' hypermobility, whereas no tendon pathology was found that explained the hypermobility in BJHS.

Matters of fiber size and myonuclear domain: Does size matter more than age?

INTRODUCTION: The relationship between fiber size and myonuclear content is poorly understood. METHODS: Biopsy cross-sections from young and old trained and untrained healthy individuals were analyzed for fiber area and myonuclei, and 2 fiber-size-dependent cluster analyses were performed. RESULTS: When comparing fibers of similar size, no effect of training or age was found for myonuclear domain. There was a linear relationship between fiber area and myonuclei per fiber (r = 0.99; P < 0.001) and a non-linear relationship between fiber area and domain (r = 0.97-0.99; P < 0.0001), with a markedly smaller domain in fibers <3,000 µm(2). A higher proportion of type II fibers <3,000 µm(2) was observed in the old subjects. CONCLUSIONS: These findings suggest that age-related reductions in myonuclear domain size could be explained by the greater proportion of small fibers. The data also highlight the usefulness of determining fiber-size-based clusters for gaining mechanistic insight into the relationship between skeletal muscle fiber size and myonuclear content.

Age-related decline in mitral peak diastolic velocities is unaffected in well-trained runners.

OBJECTIVES: We examined whether diastolic left ventricular function in young and senior lifelong endurance runners was significantly different from that in sedentary age-matched controls, and whether lifelong endurance running appears to modify the age-related decline in diastolic left ventricular function. DESIGN: The study comprised 17 senior athletes (age: 59-75 years, running distance: 30-70 km/week), 10 young athletes (age: 20-36 years, matched for running distance), and 11 senior and 12 young weight-matched sedentary controls. Peak early (E) and late (A) mitral inflow and early (e') and late (a') diastolic and systolic (s') annular longitudinal tissue Doppler velocities were measured by echocardiography during four stages (rest, supine bike exercise at 30% and 60% of maximal workload, and recovery). RESULTS: The athletes had marked cardiac remodeling, while overall differences in mitral inflow and annular tissue Doppler velocities during rest and exercise were more associated with age than with training status. The senior participants had lower E/A at rest, overall lower E, e' and s', and greater E/e' compared to the young participants (all values of P < 0.05). The athletes had greater E/A (P = 0.004), but tissue Doppler velocities were not different from those of the controls. CONCLUSIONS: Lifelong endurance running was not found to be associated with major attenuation of the age-related decline in diastolic function at rest or during exercise.

A Cross-Sectional Study Investigating Associations between Personality Traits, Glycemic Control, and BMI in Persons with Diabetes: Lolland-Falster Health Study, Denmark.

There is a growing focus on person-centered care, emphasizing the importance of respecting inter-individual differences and implementing individualized treatment initiatives. Prior research has established an association between personality traits, body mass index, and health-related behaviors. The aim of this study was to explore the potential of personality trait assessments in identifying individuals at risk of glycemic dysregulation and increasing BMI. This cross-sectional study used a dataset comprising 140 participants with diabetes who completed the Big Five personality trait questionnaire from the Lolland-Falster Health Study. Logistic regression was used to investigate associations between personality traits, glycemic control, and BMI ≥ 25. No significant associations between personality traits and glycemic control were found. There was a significant association between agreeableness and lower odds of BMI ≥ 25 in the unadjusted analysis (OR 0.54 (0.34-0.86)), which persisted after adjusting for sex, age, and education (OR 0.54 (0.33-0.89)). No significant association between glycemic control and personality traits was observed in this small sample study. However, higher levels of agreeableness were associated with a lower likelihood of having a BMI of ≥25. This preliminary study suggests that integrating personality assessments could help identify individuals at risk of increasing BMI. These findings highlight the potential of using personality traits to guide targeted interventions, offering a direction for future research.

Physiological and clinical effects of low-intensity blood-flow restricted resistance exercise compared to standard rehabilitation in adults with knee osteoarthritis-Protocol for a randomized controlled trial.

INTRODUCTION: Osteoarthritis (OA) is a common disease with high socioeconomical costs. In Denmark, standard rehabilitation (SR) consists of a combination of patient education and supervised physical exercise involving a standardized neuromuscular training program. As an evidence-based alternative, high-load (>70% 1RM) resistance training (HIRT) has shown positive rehabilitation effects in knee-OA but may not be tolerated in all patients (~25%) due to knee joint pain. However, low-load resistance training (20-40% 1RM) with concurrent partial blood-flow restriction (BFR) appears to produce effects similar to HIRT yet involving reduced joint pain during and after exercise. The aim is to examine the effect of low-load BFR training compared to SR on pain, thigh muscle mass and muscle function in adults with knee-OA. We hypothesize that 12 weeks of BFR will lead to superior improvements in pain, muscle mass and mechanical muscle function compared to SR. METHODS AND ANALYSIS: 90 participants diagnosed with radiographic knee-OA will be randomized to either BFR or SR twice a week for 12 weeks. BFR will consist of two selected lower limb strength exercises performed with an inflated pneumatic occlusion cuff. Intervention procedures in SR consist of a full 8 weeks GLA:D course followed by 4 weeks of team group training. Primary outcome variable is the change in KOOS-Pain subscale from baseline to 12 weeks. Secondary outcome variables are changes in pain sensitivity, functional performance, muscle mass and mechanical muscle function. Intention-to-treat and per-protocol analyses will be conducted. One-way analysis of variance will be performed to evaluate between-group changes. Pre-to-post intervention comparisons will be analyzed using a mixed linear model. Regression analysis will be performed to evaluate potential associations between selected outcome variables.

Assessment of the Psychometric Properties of the Danish VISA-P.

Purpose: The objective of the current study was to conduct a rigorous assessment of the psychometric properties of the Victorian Institute of Sports Assessment-patellar tendinopathy (VISA-P). Methods: Rasch analysis, confirmatory factor analysis (CFA), and multivariable linear regression were used to assess the psychometric properties of the VISA-P questionnaire in 184 Danish patients with patellar tendinopathy who had symptoms ranging from under 3 months to over 1 year. A group of 100 healthy Danish persons was included as a reference for known-group validation. Results: The analyses revealed that the 8-item VISA-P did not fit a unidimensional model, yielded at best a 3-factor model, and exhibited differential item functioning (DIF) across healthy subjects versus people with patellar tendinopathy. Conclusion: VISA-P in its present form does not satisfy a measurement model and is not a robust scale for measuring patellar tendinopathy. A new PROM for patellar tendinopathy should be developed and appropriately validated, and meanwhile, simple pain scoring (e.g., numeric rating scales) and functional tests are suggested as more appropriate outcome measures for studies of patellar tendinopathy.