Power production strategy during steady-state cycling is cadence dependent.

Crank power is produced by extension and flexion of the hip and knee joints during steady-state pedaling below 120 rpm. Despite the pedaling cadence exceeding 120 rpm during track cycling, the power production strategy for lower-limb coordination above 120 rpm is unknown. This study aimed to assess the effects of various pedaling cadences on the power production strategy of lower-limb coordination during steady-state pedaling. Twenty trained collegiate cyclists performed a 30-s steady-state pedaling exercise at 50% of maximal anaerobic power under four different conditions with 90-, 120-, 150- and 180-rpm pedaling cadences. Pedal kinetics and limb kinematics were recorded using a pedal force measurement system and motion capture system, respectively. Positive mechanical work of hip extension significantly decreased with increasing pedaling cadence (P < 0.05). In contrast, the positive mechanical work of the knee joint flexion significantly increased with increasing pedaling cadence (P < 0.05). For contribution to the total mechanical work at 150 or above rpm, the knee joint showed > 70% of the total contribution, whereas the hip joint showed < 40%. Additionally, the positive mechanical work of the hip shifted to negative mechanical work under 180-rpm condition. These results indicate that power production strategy during steady-state pedaling at 180 rpm is different from the general pedaling cadence. Therefore, specific training needs to be conducted at an excessive-high pedaling cadence such as 180 rpm to achieve high performance in track cycling.

Development of a new HISCL automated CXCL9 immunoassay.

C-X-C motif chemokine ligand 9 (CXCL9), a candidate biomarker, reflects type 1 (T1) inflammation pathology. Here, we report the analytical performance and clinical characteristics of a new CXCL9 reagent for a fully automated immunoassay device. We evaluated the limits of blank, detection, and quantitation (LoQ) along with other efficacy parameters, and the ability of the assay to report patient health, COVID-19 status, and the presence of asthma and/or interstitial lung diseases (ILDs). The coefficient of variation for 5-day total precision using two instruments was 7% across two controls, serum, and plasma panels. LoQ of 2.2 pg/mL suggested the efficacy of the assay in detecting T1 inflammation in plasma or serum; no cross-reactivity or interference was observed. We identified high serum CXCL9 levels in samples from patients with acute COVID-19 infections (n = 57), chronic bird-related hypersensitivity pneumonitis (n = 61), asthma (n = 194), and ILDs (n = 84) compared to healthy individuals (< 39.0 pg/mL). Furthermore, CXCL9 levels increased with age in asthma patients, and an opposite trend was observed for T2 inflammatory factors. These results suggest the utility of the automated CXCL9 immunoassay for measuring CXCL9 in clinical samples and reflect its role in T1 inflammation.

Acute Effect of Caffeine Supplementation on 100-m Sprint Running Performance: A Field Test.

PURPOSE: No study has assessed the acute effect of caffeine supplementation on 100-m sprint running in athletics and caffeine's net ergogenicity on 100-m sprint running remains unclear. We investigated the acute effects of caffeine supplementation on 100-m sprint running performance in a field test. METHODS: Thirteen male collegiate sprinters were subjected to 100-m sprint running time trials (TT) after the ingestion of 6 mg·kg -1 body weight caffeine or placebo supplementation in a double-blind, counterbalanced, randomized, and crossover design. Sprint velocity was measured with a laser system, and sprint time was calculated from the data in which the effects of environmental factors that would act as confounding factors on sprint time during TT were eliminated. RESULTS: The corrected 100-m sprint time was significantly shortened by 0.14 s with caffeine supplementation compared with placebo (placebo: 11.40 ± 0.39 s, caffeine: 11.26 ± 0.33 s; P = 0.007, g = -0.33). The corrected sprint time up to 60 m during TT was also significantly shorter with caffeine supplementation than with placebo ( P = 0.002). Furthermore, the mean sprint velocity for splits of 0-10 and 10-20 m was significantly increased by caffeine supplementation (all P < 0.05). CONCLUSIONS: Acute caffeine supplementation enhanced the corrected 100-m sprint time by improving the sprint performance in the first 60 m after more explosive acceleration in the early stage of the acceleration phase. Thus, for the first time, we directly demonstrated caffeine's ergogenicity on 100-m sprint performance in athletics.

The relationship between pedal force application technique and the ability to perform supramaximal pedaling cadences.

This study aimed to examine the relationship between the pedal force application technique under a specific competitive condition and the ability to perform steady-state pedaling at a supramaximal cadence during a special pedaling test. A total of 15 competitive male cyclists and 13 active, healthy men (novice cyclists, hereafter, novices) performed the pedaling technique test. The test imitated a road cycling competition condition (80% VO2 peak and a cadence of 90 rpm). Additionally, they performed a supramaximal cadence test that evaluated the ability to perform steady-state pedaling for an ultra-high cadence (range of 160-220 rpm) of 30 s stably with a 0.1 kgf. For the pedaling technique test, kinetic data were obtained by the pedal-shaped force platform at 1,000 Hz, and the pedaling technique was determined by the index of force effectiveness (IFE). For the supramaximal cadence test, kinematic data were obtained using a motion capture system at 200 Hz. The supramaximal pedaling cadence (Cmax) was determined by measuring exercise time and targeted pedaling cadence. The IFE was 48.0 ± 9.7% in cyclists and 32.0 ± 5.9% in novices. The Cmax was 215.5 ± 8.8 rpm in cyclists and 192.2 ± 13.0 rpm in novices. These values were significantly higher for cyclists than for novices. Cmax was moderately correlated with IFE (r = 0.64). No significant correlation was observed between Cmax and IFE for cyclists only; in contrast, a moderate correlation was observed between these parameters for novices only (r = 0.67). In conclusion, the pedal force application technique under a specific competitive condition is related to the ability to perform steady-state pedaling for supramaximal cadence during the test. Therefore, Cmax may be able to explain pedal force application techniques without the need for expensive devices for novices.

Role of transient receptor potential vanilloid 4 in therapeutic antifibrotic effects of pirfenidone.

Idiopathic pulmonary fibrosis (IPF) is a chronic, progressive, fatal lung disorder characterized by aberrant extracellular matrix deposition in the interstitium. Pirfenidone is an antifibrotic agent used to treat patients with IPF. Pirfenidone shows a pleiotropic mode of action, but its underlying antifibrotic mechanism is unclear. Transient receptor potential vanilloid 4 (TRPV4), which is a mechanosensitive calcium channel, was recently shown to be related to pulmonary fibrosis. To clarify the antifibrotic mechanisms of pirfenidone, we investigated whether TRPV4 blockade has a pharmacological effect in a murine model of pulmonary fibrosis and whether pirfenidone contributes to suppression of TRPV4. Our synthetic TRPV4 antagonist and pirfenidone treatment attenuated lung injury in the bleomycin mouse model. TRPV4-mediated increases in intracellular calcium were inhibited by pirfenidone. In addition, TRPV4-stimulated interleukin-8 release from cells was reduced and a delay in cell migration was abolished by pirfenidone. Furthermore, pirfenidone decreased TRPV4 endogenous ligands in bleomycin-administered mouse lungs and their production by microsomes of human lungs. We found TRPV4 expression in the bronchiolar and alveolar epithelium and activated fibroblasts of the lungs in patients with IPF. Finally, we showed that changes in forced vital capacity of patients with IPF treated with pirfenidone were significantly correlated with metabolite levels of TRPV4 endogenous ligands in bronchoalveolar lavage fluid. These results suggest that the antifibrotic action of pirfenidone is partly mediated by TRPV4 and that TRPV4 endogenous ligands in bronchoalveolar lavage fluid may be biomarkers for distinguishing responders to pirfenidone.

Thymic Adenocarcinoma with Positivity for Thyroid Transcription Factor-1 and a BRAF V600E Mutation.

Thymic adenocarcinomas are rare. We herein report for the first time a case of thymic adenocarcinoma with positivity for thyroid transcription factor-1 (TTF-1) and a BRAF V600E mutation. A 50-year-old woman had persistent suffocation and chest pain. Computed tomography revealed a 42×28-mm tumor in the anterior mediastinum. The patient underwent tumor resection using video-assisted thoracoscopic surgery. Histopathological findings showed thymic papillary adenocarcinoma, Masaoka stage II. Immunohistochemically, the tumor was positive for TTF-1. A sequencing analysis revealed a BRAF V600E mutation. The patient underwent postoperative radiotherapy and was in good health without recurrence at five months after resection.

No Correlation Between Plantar Flexor Muscle Volume and Sprint Performance in Sprinters.

The plantar flexor torque plays an important role in achieving superior sprint performance in sprinters. Because of the close relationship between joint torque and muscle size, a simple assumption can be made that greater plantar flexor muscles (i.e., triceps surae muscles) are related to better sprint performance. However, previous studies have reported the absence of these relationships. Furthermore, to examine these relationships, only a few studies have calculated the muscle volume (MV) of the plantar flexors. In this study, we hypothesized that the plantar flexor MVs may not be important morphological factors for sprint performance. To test our hypothesis, we examined the relationships between plantar flexor MVs and sprint performance in sprinters. Fifty-two male sprinters and 26 body size-matched male non-sprinters participated in this study. On the basis of the personal best 100 m sprint times [range, 10.21-11.90 (mean ± SD, 11.13 ± 0.42) s] in sprinters, a K-means cluster analysis was applied to divide them into four sprint performance level groups (n = 8, 8, 19, and 17 for each group), which was the optimal number of clusters determined by the silhouette coefficient. The MVs of the gastrocnemius lateralis (GL), gastrocnemius medialis (GM), and soleus (SOL) in participants were measured using magnetic resonance imaging. In addition to absolute MVs, the relative MVs normalized to body mass were used for the analyses. The absolute and relative MVs of the total and individual plantar flexors were significantly greater in sprinters than in non-sprinters (all p < 0.01, d = 0.64-1.39). In contrast, all the plantar flexor MV variables did not differ significantly among the four groups of sprinters (all p > 0.05, η2 = 0.02-0.07). Furthermore, all plantar flexor MV variables did not correlate significantly with personal best 100 m sprint time in sprinters (r = -0.253-0.002, all p > 0.05). These findings suggest that although the plantar flexor muscles are specifically developed in sprinters compared to untrained non-sprinters, the greater plantar flexor MVs in the sprinters may not be important morphological factors for their sprint performance.

Pacing Strategy in Men's 400 m Hurdles Accounting for Temporal and Spatial Characteristics of Elite Athletes.

The final result in a 400 m hurdles race (400mH) is relative to the motor preparation, technique of clearing hurdles as well as the adopted strategy of the race, including temporal aspects (split times in particular parts of the race) and spatial elements (the number of strides taken between subsequent hurdles). The objective of the study was to identify an optimal strategy for the 400mH race, including the stride pattern and split times. Data employed for this study were derived from results of 273 races held during the men's finals of international events (Olympic Games, World and European Championships) held from 1968 to 2015. To determine the strategies in the race, three main hurdle sections were identified - 1-4H, 4-7H and 7-10H. In each part, the fast (best results), average and slow (worst results) performing groups of hurdlers were distinguished. The analysis of adopted strategies was carried out taking into account 26 variables (main, basic, temporal and spatial). Basic statistical data, correlations and analysis of variance (ANOVA) were used. Results highlight the use of a variety of strategies, of which selection depends, among others, on body composition and the level of motor abilities (speed, speed endurance and explosive strength), as well as hurdling technique. Especially, the endurance strategy appears to be the most effective one, as it is a characteristic of best performances of many hurdlers. The analysis demonstrates that at the highest sports level the strategy of 400 m hurdles should be analyzed individually.

Kinetics in lumbosacral and lower-limb joints of sprinters during barbell hip thrust compared to deadlift and back squat.

Joint kinetic characteristics during the eccentric phase are important in resistance exercises because eccentric actions with elastic potential energy storage lead to the energy recoil with large joint moment and power generation during the subsequent concentric phase. Previous studies assessed the force production capacity in the barbell hip thrust; however, these were reported by the methodology using only surface electromyographic amplitudes recorded in the lower back and thigh muscles and did not focus on eccentric action. This study aimed to determine kinetic characteristics of lumbosacral, hip and knee joints of sprinters during the eccentric and concentric phases in a barbell hip thrust, compared to those of deadlift and back squat. Eleven well-trained male sprinters participated in this study. Each participant performed two full ranges of motion repetition using their previously determined six-repetition maximum loads. During strength exercises, reflective marker displacements attached to the body and a barbell were captured using 22 high-speed cameras, and ground reaction forces were captured using 4 force plates simultaneously. In the barbell hip thrust, as well as deadlift, the peak values of the lumbosacral and hip extension moments were generated almost immediately after the eccentric phase and were 24% and 42% larger than those in the back squat, respectively. In the knee joint, the largest was the peak extension moment in the back squat (155 ± 28 Nm), followed in order by that in the barbell hip thrust (66 ± 33 Nm) and that in the deadlift (24 ± 27 Nm). These demonstrated that a barbell hip thrust, as well as deadlift, can be a resistance exercise to strengthen the lower back and posterior thigh muscles. Thus, these resistance exercises may be able to be used separately according to their intended purposes, enabling transformations of strength training to specific dynamic motions such as sprint running.

Relationship of the knee extensor strength but not the quadriceps femoris muscularity with sprint performance in sprinters: a reexamination and extension.

PURPOSE: This study examined the relationships of knee extensor strength and quadriceps femoris size with sprint performance in sprinters. METHODS: Fifty-eight male sprinters and 40 body size-matched male non-sprinters participated in this study. The knee extensor isometric and isokinetic strengths were measured using a dynamometer. The isokinetic strength measurements were performed with slow and fast velocities at 60°/s and 180°/s, respectively. The quadriceps femoris muscle volume (MV) was measured using magnetic resonance imaging. The relative knee extensor strengths and quadriceps femoris MV were calculated by normalizing to body mass. RESULTS: Absolute and relative knee extensor strengths during two velocity isokinetic contractions, but not during isometric contraction, were significantly higher in sprinters than in non-sprinters (P = 0.047 to < 0.001 for all). Such a significant difference was also observed for relative quadriceps femoris MV (P = 0.018). In sprinters, there were positive correlations between all three knee extensor strengths and quadriceps femoris MV (r = 0.421 to 0.531, P = 0.001 to < 0.001 for all). The absolute and relative strengths of the fast-velocity isokinetic knee extension correlated negatively with personal best 100-m sprint time (r = -0.477 and -0.409, P = 0.001 and < 0.001, respectively). In contrast, no such significant correlations were observed between absolute and relative quadriceps femoris MVs and personal best 100-m sprint time. CONCLUSIONS: These findings suggest that despite the presence of the relationship between muscle strength and size, the knee extensor strength may be related to superior sprint performance in sprinters independently of the quadriceps femoris muscularity.

Prognostic value of 6-min walk stress echocardiography in patients with interstitial lung disease.

BACKGROUND: The 6-min walk test (6MWT) provides prognostic information for patients with interstitial lung disease (ILD). Parameter determined by Doppler echocardiography after the 6MWT (6 MW stress echocardiography) is shown to be a predictor of future development of pulmonary hypertension in patients with connective tissue disease. However, the clinical utility of 6 MW stress echocardiography in predicting cardiopulmonary events in patients with ILD remains unknown. We examined whether parameters determined by 6 MW stress echocardiography independent predictors of adverse events in patients with ILD. METHODS: Echocardiographic examinations were performed in 68 consecutively enrolled patients with ILD (age, 65 ± 10 years, 65% men). A pressure gradient of tricuspid regurgitation (TRPG) and pulmonary vascular resistance (PVRecho) calculated using the following formula [PVRecho = (peak velocity of TR × 10/time-velocity integral of right ventricular outflow (RVOT-VTI)) + 0.16] were measured at baseline and at post 6MWT. Data for parameters of pulmonary functional tests and for 6MWT were collected. RESULTS: During a mean follow-up period of 22 ± 12 months, 22 patients experienced cardiopulmonary events. In univariate analysis, %VC, TRPG, PVRecho, TRPG post 6MWT, and PVRecho post 6MWT were significantly associated with cardiopulmonary events. Multivariate analysis using the Cox proportional hazards model indicated that %VC [hazard ratio (HR): 0.97, p = 0.009] and PVRecho post 6MWT (HR: 1.77, p = 0.004) were independent predictors of cardiopulmonary events in patients with ILD. CONCLUSIONS: In addition to parameters of pulmonary function tests, increased PVRecho post 6MWT is a significant predictor of cardiopulmonary events in patients with ILD. A 6 MW stress echocardiography is useful in assessing the risk of adverse events in patients with ILD.

Trunk and lower limb muscularity in sprinters: what are the specific muscles for superior sprint performance?

OBJECTIVE: The major purpose of this study was to determine the specific muscle(s) for superior sprint performance in sprinters. The cross sectional areas (CSAs) of ten muscles of the trunk and lower limb were measured using magnetic resonance images in 56 male sprinters and 40 male non-sprinters. In addition to the absolute CSA, to minimize the effect of difference in body size among participants, the relative CSA normalized to body mass was used for analysis of this study. RESULTS: Absolute and relative CSAs of most trunk and lower limb muscles, including the psoas major (PM) and gluteus maximus (GM), were significantly larger in sprinters than in non-sprinters (all P < 0.001, d = 0.91 to 1.82). The absolute and relative CSAs of the PM and GM correlated significantly with personal best 100-m sprint time in sprinters (r = - 0.363 to - 0.388, all P < 0.01). A stepwise multiple regression analysis revealed that both CSAs of absolute PM and relative GM were predictive variables for the personal best 100 m sprint time in sprinters (ß = - 0.289 and - 0.287, respectively, both P < 0.05). These findings suggest that the PM and GM may be specific muscles for superior sprint performance in sprinters.

Achilles Tendon Length Is Not Related to 100-m Sprint Time in Sprinters.

This study examined the relationship between Achilles tendon (AT) length and 100-m sprint time in sprinters. The AT lengths at 3 different portions of the triceps surae muscle in 48 well-trained sprinters were measured using magnetic resonance imaging. The 3 AT lengths were calculated as the distance from the calcaneal tuberosity to the muscle-tendon junction of the soleus, gastrocnemius medialis, and gastrocnemius lateralis, respectively. The absolute 3 AT lengths did not correlate significantly with personal best 100-m sprint time (r = -.023 to .064, all Ps > .05). Furthermore, to minimize the differences in the leg length among participants, the 3 AT lengths were normalized to the shank length, and the relative 3 AT lengths did not correlate significantly with personal best 100-m sprint time (r = .023 to .102, all Ps > .05). Additionally, no significant correlations were observed between the absolute and relative (normalized to body mass) cross-sectional areas of the AT and personal best 100-m sprint time (r = .012 and .084, respectively, both Ps > .05). These findings suggest that the AT morphological variables, including the length, may not be related to superior 100-m sprint time in sprinters.

CXCL9, CXCL10, and CXCL11; biomarkers of pulmonary inflammation associated with autoimmunity in patients with collagen vascular diseases-associated interstitial lung disease and interstitial pneumonia with autoimmune features.

INTRODUCTION: Interstitial lung disease (ILD) is a heterogeneous group of diseases characterized by varying degrees of lung inflammation and/or fibrosis. We investigated biomarkers to infer whether patients with collagen vascular diseases associated ILD (CVD-ILD) and interstitial pneumonia with autoimmune features (IPAF) benefit from immunosuppressive therapy. MATERIALS AND METHODS: We retrospectively investigated patients with CVD-ILD, IPAF, and idiopathic pulmonary fibrosis (IPF) between June 2013 and May 2017 at our department. First, we assessed differences in serum and bronchoalveolar lavage fluid (BALF) levels of cytokines between groups. Second, we assessed the associations of patient's clinical variables with serum and BALF levels of those cytokines that were different between groups. Finally, we assessed the associations of diagnosis and response to immunosuppressive therapy with serum levels of those cytokines that were different between groups. RESULTS: We included 102 patients (51 with IPF, 35 with IPAF, and 16 with CVD-ILD). Serum and BALF levels of CXCL9, CXCL10, and CXCL11 were significantly elevated in patients with IPAF or CVD-ILD compared with those in patients with IPF. BALF levels of CXCL9 and CXCL10 were correlated with the percentages of lymphocytes and macrophages in BALF. Serum levels of CXCL9 and CXCL10 were correlated with BALF levels. Serum levels of CXCL9, CXCL10, and CXCL11 were correlated C-reactive protein, percent predicted forced vital capacity, alveolar-arterial oxygen difference, and the percentages of lymphocytes and macrophages in BALF. Serum levels of CXCL9, CXCL10, and CXCL11 showed moderate accuracy to distinguish patients with CVD-ILD from those with IPAF and IPF. Pre-treatment serum levels of CXCL9 and CXCL11 showed strong positive correlations with the annual forced vital capacity changes in patients with IPAF and CVD-ILD treated with immunosuppressive drugs. CONCLUSIONS: Serum CXCL9, CXCL10, and CXCL11 are potential biomarkers for autoimmune inflammation and predictors of the immunosuppressive therapy responses in ILD with background autoimmunity.

Comparison of the relative muscle volume of triceps surae among sprinters, runners, and untrained participants.

Muscle hypertrophy is considered more prominent in fast-twitch than in slow-twitch muscles. This leads to the hypothesis that the relative muscle volume of the medial gastrocnemius (MG) and lateral gastrocnemius (LG) becomes larger than that of the soleus (SOL) in highly trained participants because MG and LG include more fast-twitch muscles than SOL. Thus, we compared relative muscle volume among highly trained sprinters, long-distance runners, and untrained participants to examine whether the above hypothesis is correct. Magnetic resonance imaging was used to calculate the muscle volume of MG, LG, and SOL from 126 participants. The total muscle volume of the three muscles and the relative muscle volume of each muscle with respect to the total muscle volume were calculated. The total muscle volume was significantly larger in the sprinters than in the long-distance runners and untrained participants. The relative muscle volume of MG was significantly larger in the sprinters than in the long-distance runners and untrained participants and that of SOL was significantly smaller in the sprinters than in the long-distance runners and untrained participants. These results indicate that the relative muscle volume can vary among participants, possibly due to fiber type-dependent muscle hypertrophy.

Calcaneus height is a key morphological factor of sprint performance in sprinters.

This study examined the relationships between the foot bone morphologies and sprint performance in sprinters. Foot images in 56 male sprinters obtained using magnetic resonance imaging. The relative lengths of the forefoot bones of the big and second toes, which were calculated as total lengths of the forefoot bones for each toe normalized to the foot length, correlated significantly with personal best 100-m sprint time (r = - 0.293 and - 0.459, both Ps < 0.05). The relative lengths of the rearfoot talus and calcaneus normalized to the foot length also correlated significantly with the sprint performance (r = - 0.378 and - 0.496, both Ps < 0.05). Furthermore, the relative height of the calcaneus, but not the talus, normalized to body height correlated significantly with sprint performance (r = - 0.690, P < 0.001). Additionally, the relative calcaneus height correlated significantly with the foot arch height index (r = 0.420, P = 0.001), and the foot arch height index correlated significantly with sprint performance (r = - 0.517, P < 0.001). These findings suggest that the taller calcaneus may be a key morphological factor for achieving superior sprint performance, potentially via modeling the longer forefoot and rearfoot bones and functional foot morphology in sprinters.

A pilot study on a potential relationship between leg bone length and sprint performance in sprinters; are there any event-related differences in 100-m and 400-m sprints?

OBJECTIVE: This study examined the relationship between leg bone length and sprint performance in sprinters. The leg bone lengths in 28 100-m specialized sprinters and 28 400-m specialized sprinters were measured using magnetic resonance imaging. The lengths of the upper and lower leg bones were assessed by calculating the lengths of the femur and tibia, respectively. To minimize differences in body size among participants, both bone lengths were normalized to body height. The ratio of the tibial length to femoral length was calculated to evaluate the interaction between the lengths of the upper and lower leg bones. International Amateur Athletic Federation (IAAF) scores, based on the personal best times of the sprinters in each group were used as parameters for sprint performance. RESULTS: There were no significant correlations between absolute and relative lengths of the femur and tibia and IAAF scores in both 100-m and 400-m sprinters. By contrast, the ratio of the tibial length to femoral length correlated significantly with IAAF score in 400-m sprinters (r = 0.445, P = 0.018), but not 100-m sprinters. These findings suggest that the leg bone lengths may play an important role in achieving superior long sprint performance in 400-m specialized sprinters.

Correction to: Surfactant protein A as a biomarker of outcomes of anti-fibrotic drug therapy in patients with idiopathic pulmonary fibrosis.

Following publication of the original article [1], the authors have flagged that there is an error in Fig. 3.