CollagenSupplementation Augments Strength Training-Induced Gains in Tendon Size and Rate of Force Development in Elite Female Master Field Hockey Athletes.

This study investigated the validity and reliability of measuring patellar tendon (PT) cross-sectional area (CSA) using magnetic resonance imaging (MRI) and ultrasound (US) imaging. Nineteen healthy participants (10 women, 9 men) participated in three imaging sessions of the PT, once via MRI and twice via US, with image acquisition conducted by two raters, one experienced (rater 2) and one inexperienced (rater 1). All PT segmentations were analyzed by both raters. The validity of US-derived estimates of PT CSA against MRI estimates was analyzed using linear regression. Within-day reliability of US and MRI measurements and between-day reliability of US measurements were quantified using typical error (TE) and intra-class correlation coefficients (ICC3,1). There was good agreement between US- and MRI-derived estimations of PT CSA (standard errors of the estimate of 3.3 mm2 for rater 1 and 2.6 mm2 for rater 2; Pearson's r=0.97 and 0.98 for raters 1 and 2, respectively). Within-session reliability for estimations of total PT CSA from US and MRI were excellent (ICC3,1 >0.95, coefficient of variation [CV] <4.1%, TE=1.3-3.6 mm2. Between-day reliability for US was excellent (ICC3,1 >0.97, CV <2.7%, TE=1.6-2.3 mm2), with little difference between raters. These findings suggest that MRI and US both provide reliable estimates of PT CSA and that US can provide a valid measure of PT CSA.

Background:Patellar tendinopathy is a common chronic condition caused by mechanical loading that leads to patellar tendon (PT) degeneration, with an estimated incidence of 13% across all sports in adolescents. Musculoskeletal ultrasound (MSK-US) evaluation is becoming more common in the diagnostic process, but normative data are extremely rare for the adolescent population. These normative data are needed to aid in proper interpretation of the MSK-US image.Purpose:The purpose of this study was to determine standard reference values for thickness, width, and cross-sectional area (CSA) of the PT using MSK-US in asymptomatic adolescent athletes.Methods:IRB approval, parental consent, and athlete assent were obtained prior to data collection. Bilateral PT were scanned using a portable US unit with a 12-4MHz linear array transducer. Long axis images were captured at the apex and 1cm distal to the patella, 1 cm proximal to the insertion and at the PT insertion (Figure 1a & 1b). Short axis images were captured 1 cm proximal and distal to the attachments. PT thickness, width, and CSA were measured using ImageJ by a single evaluator. Additional exploratory analyses were also conducted.Results:Seventy-one adolescent athletes (27 males, 44 females) between 11-18 years old (13.8 ±1.8 years) volunteered. Mean values for PT thickness, width, and CSA are found in Table 1. Significant differences in PT thickness and CSA between sex were identified at each measurement location (P<.05), with males ranging 4.0-9.9 mm thicker than females. PT width was not significantly different proximally or distally. The left proximal PT was significantly wider than right (P<.0001), but no other side differences were found. Lastly, significant weak positive correlations were present in distal tendon CSA with height (left PT: r(52)=.348, P=.014, right PT: r(49)=.369, P=.007) and weight (left PT: r(50 )=.290, P=.041). There was no correlation with age.Conclusion:These data represent one of the largest healthy cohorts of adolescent athletes from which normative data have been collected. This preliminary analysis reveals some interesting trends, such as the thickness of the PT is greatest at the insertion and origin, while thinner at mid-tendon, with the insertion the thicker of the two. Age was not correlated with PT size, but distal PT CSA was larger with taller and heavier individuals. These data will contribute to the paucity of adolescent PT MSK-US data, which should aid clinicians in interpretation, diagnostic accuracy, and management of active adolescent patients with patellar tendinopathy.Figure 1.Long axis US images of the proximal (a) and distal patellar tendon (b)Table 1.Patellar tendon means and standard deviation

To examine if cross-sectional area (CSA) differs along the length of the human patellar tendon (PT), and if there is PT hypertrophy in response to resistance training. Twelve healthy young men underwent baseline and post-training assessments. Maximal isometric knee extension strength (MVC) was determined unilaterally in both legs. PT CSA was measured at the proximal-, mid- and distal PT level and quadriceps muscle CSA was measured at mid-thigh level using magnetic resonance imaging. Mechanical properties of the patellar tendons were determined using ultrasonography. Subsequently, subjects performed 12 weeks of heavy resistance knee extension training with one leg (Heavy-leg), and light resistance knee extension training with the other leg (Light-leg). The MVC increased for heavy-leg (15 +/- 4%, P < 0.05), but not for light-leg (6 +/- 4%). Quadriceps CSA increased in heavy-legs (6 +/- 1%, P < 0.05) while unchanged in light-legs. Proximal PT CSA (104 +/- 4 mm(2)) was smaller than the mid-tendon CSA (118 +/- 3 mm(2)), which again was smaller than distal tendon CSA (127 +/- 2 mm(2), P < 0.05). Light-leg PT CSA increased by 7 +/- 3% (P < 0.05) at the proximal tendon level, but was otherwise unchanged. Heavy-leg PT CSA increased at the proximal and distal tendon levels by 6 +/- 3% and 4 +/- 2% respectively (P < 0.05), but was unchanged at the mid tendon level. PT stiffness increased in heavy-legs (P < 0.05) but was unchanged in light-legs. Modulus remained unchanged in both legs. To our knowledge, this study is the first to report tendon hypertrophy following resistance training. Further, the data show that the human PT CSA varies along the length of the tendon.

This study compared the muscle and tendon morphology of an extraordinarily strong individual, a World's Strongest Man and deadlift champion (WSM), with that of various other athletic, trained, and untrained populations. The WSM completed the following: 1) 3.0-T MRI scans, to determine the volume of 22 individual lower limb muscles, 5 functional muscle groups, patellar tendon (PT) cross-sectional area (CSA), and PT moment arm; and 2) countermovement jumps (CMJ) and isometric midthigh pull (IMTP) contractions. The WSM was compared with previously assessed groups from our laboratory (muscle and tendon) and the wider research literature (CMJ and IMTP). The WSM's CMJ peak power (9,866 W) and gross (9,171 N) and net (7,480 N) IMTP peak forces were higher than any previously published values. The WSM's overall measured leg muscle volume was approximately twice that of untrained controls (+96%) but with pronounced anatomical variability in the extent of muscular development. The plantar flexor group (+120%) and the guy rope muscles (sartorius, gracilis, and semitendinosus: +140% to +202%), which stabilize the pelvis and femur, demonstrated the largest differences relative to that of untrained controls. The WSM's pronounced quadriceps size (greater than or equal to twofold vs. untrained) was accompanied by modest PT moment arm differences and, notably, was not matched by an equivalent difference in PT CSA (+30%). These results provide novel insight into the musculotendinous characteristics of an extraordinarily strong individual, which may be toward the upper limit of human variation, such that the WSM's very pronounced lower limb muscularity also exhibited distinct anatomical variability and with muscle size largely uncoupled from tendon size.NEW & NOTEWORTHY Lower-body muscle size of an extraordinarily strong individual, a World's Strongest Man and deadlift champion (WSM), was approximately twice that of controls but was underpinned by pronounced anatomical variability in the extent of muscular development (+23-202%): the plantar flexor group and guy rope muscles demonstrating the largest differences. The WSM's quadriceps size (more than or equal to twice that of controls) contrasted with modest differences in patella tendon moment arm (+18%) and was uncoupled from patellar tendon size (+30%).

COVID-19 is associated with musculoskeletal disorders. Ultrasound is a tool to assess muscle architecture and tendon measurements, offering an idea of the proportion of the consequences of the disease, since significant changes directly reflect the reduction in the ability to produce force and, consequently, in the functionality of the patient; however, its application in post-COVID-19 infection needs to be determined. We aimed to assess the intra- and inter-rater reliability of ultrasound measures of the architecture of the vastus lateralis (VL), rectus femoris (RF), vastus medialis (VM), gastrocnemius lateralis (GL), gastrocnemius medialis (GM), soleus (SO), and tibialis anterior (TA) muscles, as well as the patellar tendon (PT) cross-sectional area (CSA) in post-COVID-19 patients. An observational, prospective study with repeated measures was designed to evaluate 20 post-COVID-19 patients, who were measured for the pennation angle (θp), fascicular length (Lf), thickness, echogenicity of muscles, CSA and echogenicity of the PT. The intra-class correlation coefficient (ICC) and 95% limits of agreement were used. The intra-rater reliability presented high or very high correlations (ICC = 0.71–1.0) for most measures, except the θp of the TA, which was classified as moderate (ICC = 0.69). Observing the inter-rater reliability, all the evaluations of the PT, thickness and echogenicity of the muscles presented high or very high correlations. For the Lf, only the RF showed as low (ICC = 0.43), for the θp, RF (ICC = 0.68), GL (ICC = 0.70) and TA (ICC = 0.71) moderate and the SO (ICC = 0.40) low. The ultrasound reliability was acceptable for the muscle architecture, muscle and tendon echogenicity, and PT CSA, despite the low reliability for the Lf and θp of the RF and SO, respectively.

Collagen peptide supplementation has been reported to enhance synthesis rates or growth in a range of musculoskeletal tissues and could enhance tendinous tissue adaptations to resistance training (RT). This double-blind placebo-controlled study aimed to determine if tendinous tissue adaptations, size (patellar tendon cross-sectional area (CSA) and vastus lateralis (VL) aponeurosis area), and mechanical properties (patellar tendon), after 15 wk of RT, could be augmented with collagen peptide (CP) versus placebo (PLA) supplementation. Young healthy recreationally active men were randomized to consume either 15 g of CP ( n = 19) or PLA ( n = 20) once every day during a standardized program of lower-body RT (3 times a week). Measurements pre- and post-RT included patellar tendon CSA and VL aponeurosis area (via magnetic resonance imaging), and patellar tendon mechanical properties during isometric knee extension ramp contractions. No between-group differences were detected for any of the tendinous tissue adaptations to RT (ANOVA group-time, 0.365 ≤ P ≤ 0.877). There were within-group increases in VL aponeurosis area (CP, +10.0%; PLA, +9.4%), patellar tendon stiffness (CP, +17.3%; PLA, +20.9%) and Young's modulus (CP, +17.8%; PLA, +20.6%) in both groups (paired t -tests (all), P ≤ 0.007). There were also within-group decreases in patellar tendon elongation (CP, -10.8%; PLA, -9.6%) and strain (CP, -10.6%; PLA, -8.9%) in both groups (paired t -tests (all), P ≤ 0.006). Although no within-group changes in patellar tendon CSA (mean or regional) occurred for CP or PLA, a modest overall time effect ( n = 39) was observed for mean (+1.4%) and proximal region (+2.4%) patellar tendon CSA (ANOVA, 0.017 ≤ P ≤ 0.048). In conclusion, CP supplementation did not enhance RT-induced tendinous tissue remodeling (either size or mechanical properties) compared with PLA within a population of healthy young men.

The effect of different strength training regimes, and in particular training utilizing brief explosive contractions, on tendinous tissue properties is poorly understood. This study compared the efficacy of 12 weeks of knee extensor explosive-contraction (ECT; n = 14) vs. sustained-contraction (SCT; n = 15) strength training vs. a non-training control (n = 13) to induce changes in patellar tendon and knee extensor tendon–aponeurosis stiffness and size (patellar tendon, vastus-lateralis aponeurosis, quadriceps femoris muscle) in healthy young men. Training involved 40 isometric knee extension contractions (three times/week): gradually increasing to 75% of maximum voluntary torque (MVT) before holding for 3 s (SCT), or briefly contracting as fast as possible to ∼80% MVT (ECT). Changes in patellar tendon stiffness and Young’s modulus, tendon–aponeurosis complex stiffness, as well as quadriceps femoris muscle volume, vastus-lateralis aponeurosis area and patellar tendon cross-sectional area were quantified with ultrasonography, dynamometry, and magnetic resonance imaging. ECT and SCT similarly increased patellar tendon stiffness (20% vs. 16%, both p < 0.05 vs. control) and Young’s modulus (22% vs. 16%, both p < 0.05 vs. control). Tendon–aponeurosis complex high-force stiffness increased only after SCT (21%; p < 0.02), while ECT resulted in greater overall elongation of the tendon–aponeurosis complex. Quadriceps muscle volume only increased after sustained-contraction training (8%; p = 0.001), with unclear effects of strength training on aponeurosis area. The changes in patellar tendon cross-sectional area after strength training were not appreciably different to control. Our results suggest brief high force muscle contractions can induce increased free tendon stiffness, though SCT is needed to increase tendon–aponeurosis complex stiffness and muscle hypertrophy.

The aim of the present study was to identify neuromuscular, biochemical, and endocrine markers of fatigue after Rugby League match play. Seventeen elite Rugby League players were monitored for a single match. Peak rate of force development (PRFD), peak power (PP), and peak force (PF) were measured during a countermovement jump (CMJ) on a force plate pre and postmatch play. Saliva and blood samples were collected 24 hours prematch, 30 minutes prematch, 30 minutes postmatch, and then at 24-hour intervals for a period of 120 hours to determine plasma creatine kinase concentration ([CK]) and salivary cortisol concentration ([sCort]). There were significant (p < 0.05) decreases in PRFD and PP up to 24 hours postmatch with PF significantly (p < 0.05) decreased immediately postmatch. The [sCort] significantly (p < 0.05) increased from 24 hours prematch to 30 minutes prematch and up to 24 hours postmatch compared with 24 hours prematch. Plasma [CK] significantly (p < 0.05) increased 30 minutes postmatch with a peak occurring 24 hours postmatch and remained elevated above 24 hours prematch for at least 120 hours postmatch. There were significant (p < 0.05) correlations between the increase in [CK] and reduction in PRFD 30 minutes postmatch and 24 hours postmatch. The [sCort] was significantly (p < 0.05) correlated with the reduction in PF 30 minutes postmatch. Results demonstrate that neuromuscular function is compromised for up to 48 hours after match play. Elevated [CK] despite 120-hour recovery indicate that damage to muscle tissue after Rugby League match play may persist for at least 5 days postmatch. Despite the prolonged presence of elevated [CK] postmatch, strength training 48 hours postmatch may have resulted in a compensatory increase in PRFD supporting the inclusion of strength training during the short-term postmatch recovery period.

Objective. Rheumatoid arthritis (RA) and ankylosing spondylitis (AS) lead to inflammation in tendons and peritendinous tissues, but effects on biomechanical tendon function are unknown. This study investigated patellar tendon (PT) properties in stable, established RA and AS patients. Methods. We compared 18 RA patients (13 women, 59.0 ± 2.8 years, mean ± SEM) with 18 age- and sex-matched healthy controls (58.2 ± 3.2 years), and 12 AS patients (4 women, 52.9 ± 3.4 years) with 12 matched controls (54.5 ± 4.7 years). Assessments with electromyography, isokinetic dynamometry, and ultrasound included quadriceps muscle force and cross-sectional area (CSA), PT stiffness, and PT CSA. Additionally, measures of physical function and disease activity were performed. Results. PT stiffness and physical function were lower in RA and AS patients compared to healthy controls, without a significant difference in force production. PT CSA was significantly larger leading to reduction in Young's modulus (YM) in AS, but not in RA. Conclusion. The adverse changes in PT properties in RA and AS may contribute to their impaired physical function. AS, but not RA, leads to PT thickening without increasing PT stiffness, suggesting that PT thickening in AS is a disorganised repair process. Longitudinal studies need to investigate the time course of these changes and their response to exercise training.

BackgroundRegular 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.MethodsSeventeen 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).ResultsThirty 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.ConclusionDespite 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.

BackgroundThe study aimed to examine the impact of combined oral contraceptive pill (OC) use on patellar tendon (PT) adaptation to resistance training in young women.MethodsFifteen users of OC (28 ± 3 years) (OC group) and 17 eumenorrheic non-users (32 ± 5 years) (NOC group) performed heavy resistance training of the knee extensors over a period equivalent to three menstrual or pill cycles. Maximal isometric strength of the knee extensor muscles, PT cross-sectional area (CSA), tensile stiffness, and shear wave velocity (SWV) were measured before and after the intervention using combined ultrasonography and dynamometry.ResultsThe training period increased maximal isometric strength in both groups (≈11%, P < 0.001) with no significant interaction with OC use (p = 0.965). Likewise, a small yet significant increase in proximal tendon CSA was observed (1.5 ± 1.6% for both groups, main training effect P < 0.001) without any significant interaction with OC use (p = 0.267). Tendon tensile stiffness also increased significantly (18.9 ± 26.3% in the OC group and 28.2 ± 35.1% in the NOC group, main effect: P < 0.001) but was not significantly affected by OC use (interaction effect: p = 0.428). Tendon SWV measurements yielded similar results, indicating a main effect of training (+12% on average, p = 0.024) but no significant interaction with OC use.ConclusionThese findings suggest that OC use does not affect the increase in PT CSA and mechanical properties following short-term resistance training in young untrained females.

Background: Anabolic-androgenic steroids (AASs) are synthetic derivatives of testosterone that are abused by athletes to enhance their physical appearance and performance. AAS abusers have an increased risk of tendon ruptures compared with nonusers, and it has been proposed that AASs damage tendon tissue. Only a few human studies have investigated the effect of AASs on tendon tissue, and to our knowledge, there are no data on female sex. Purpose/Hypothesis: The purpose was to investigate the effect of current and former abuse of AASs on the patellar tendon (PT). It was hypothesized that AASs would not affect tendon tissue. Study Design: Cross-sectional study; Level of evidence, 3. Methods: This study included recreational athletes with current (female: n = 4; male: n = 18; total: n = 22) or former (female: n = 5; male: n = 7; total: n = 12) AAS abuse and nonusers (female: n = 5; male: n = 9; total: n = 14). The authors investigated the proportion of tendon injuries, PT cross-sectional area by magnetic resonance imaging, mechanical properties by ultrasound, gene expression levels of connective tissue proteins, and cell density by histological staining from tendon biopsy samples. Results: The combined AAS group (both current and former abusers) reported a higher proportion of upper body tendon injuries compared with nonusers (79.4% vs 28.6%, respectively; P = .002). There was no difference in PT cross-sectional area (P = .918) or cell density (fascicular matrix: P = .413; interfascicular matrix: P = .982) between current AAS abusers, former AAS abusers, and nonusers. There was a greater expression of IGF-1 mRNA in current AAS abusers compared with nonusers (P = .043), but there were no group differences in other mRNA targets. Former AAS abusers had significantly higher tendon deformation (P = .030) and strain (P = .026) at common force compared with nonusers. There were no significant differences between male and female participants in the effect of AASs on tendon tissue. Conclusion: These data show that the PT itself was not severely affected by AAS abuse.

Ultrasound does not provide reliable results for the measurement of the patellar tendon cross sectional area

The purpose of this study was to investigate the effect of a supplementation with specific collagen peptides (SCP) combined with resistance training (RT) on changes in structural properties of the patellar tendon. Furthermore, tendon stiffness as well as maximal voluntary knee extension strength and cross-sectional area (CSA) of the rectus femoris muscle were assessed. In a randomized, placebo-controlled study, 50 healthy, moderately active male participants completed a 14-week resistance training program with three weekly sessions (70–85% of 1 repetition maximum [1RM]) for the knee extensors. While the SCP group received 5g of specific collagen peptides daily, the other group received the same amount of a placebo (PLA) supplement. The SCP supplementation led to a significant greater (p < 0.05) increase in patellar tendon CSA compared with the PLA group at 60% and 70% of the patellar tendon length starting from the proximal insertion. Both groups increased tendon stiffness (p < 0.01), muscle CSA (p < 0.05) and muscular strength (p < 0.001) throughout the intervention without significant differences between the groups. The current study shows that in healthy, moderately active men, supplementation of SCP in combination with RT leads to greater increase in patellar tendon CSA than RT alone. Since underlying mechanisms of tendon hypertrophy are currently unknown, further studies should investigate potential mechanisms causing the increased morphology adaptions following SCP supplementation. Trial registration: German Clinical Trials Register identifier: DRKS00029244..

Because rate of force development (RFD) is an emerging outcome measure for the assessment of neuromuscular function in unfatigued conditions, and it represents a valid alternative/complement to the classical evaluation of pure maximal strength, this scoping review aimed to map the available evidence regarding RFD as an indicator of neuromuscular fatigue. Thus, following a general overview of the main studies published on this topic, we arbitrarily compared the amount of neuromuscular fatigue between the “gold standard” measure (maximal voluntary force, MVF) and peak, early (≤100 ms) and late (>100 ms) RFD. Seventy full-text articles were included in the review. The most-common fatiguing exercises were resistance exercises (37% of the studies), endurance exercises/locomotor activities (23%), isokinetic contractions (17%), and simulated/real sport situations (13%). The most widely tested tasks were knee extension (60%) and plantar flexion (10%). The reason (i.e., rationale) for evaluating RFD was lacking in 36% of the studies. On average, the amount of fatigue for MVF (−19%) was comparable to late RFD (−19%) but lower compared to both peak RFD (−25%) and early RFD (−23%). Even if the rationale for evaluating RFD in the fatigued state was often lacking and the specificity between test task and fatiguing exercise characteristics was not always respected in the included studies, RFD seems to be a valid indicator of neuromuscular fatigue. Based on our arbitrary analyses, peak RFD and early phase RFD appear even to be more sensitive to quantify neuromuscular fatigue than MVF and late phase RFD.