Foam rolling and tissue flossing of the triceps surae muscle: an acute effect on Achilles tendon stiffness, jump height and sprint performance - a randomized controlled trial

This study aimed to investigate an acute effect of foam rolling and tissue flossing of the Triceps Surae muscle on Achilles tendon stiffness, jump height and sprint performance at different time points. The participants were academic athletes (n = 32) aged between 22 and 24 years; randomly allocated into two groups: foam rolling (ROLL) and tissue flossing (FLOSS). The participants were tested at baseline and 5-min, 15-min, 30-min, 45-min, and 60-min after ROLL and FLOSS for Achilles tendon stiffness (ATstiffeness) at three reference locations: (1) tendon's origin, (2) ankle joint height and (3) intermuscular septum of the gastronomies muscle; countermovement jump (CMJ); and sprint performance at 15-m (SPRINT15 m). The analysis of stiffness revealed a significant decrease in ATstiffness from baseline to Post-60 (p ≤ 0.001) for three locations in the FLOSS group (p ≤ 0.001). In FLOSS, a significant increase was observed from Post-15 to Post-60 (all p≤0.001) in CMJ. We found also a significant decrease in SPRINT15 m in FLOSS in all-time points (p ≤ 0.001), however, SPRINT15 m decreased in Post-5 min, Post-15 min, and Post-30 min (p ≤ 0.001 for all) in ROLL. The current study suggested that both groups enhanced performance up to 60 min after the intervention, caused by mitigating excessive stiffness.

Effect of applied cadence in repeated sprint cycling on muscle characteristics

PURPOSE

This study aimed to investigate physiological responses, muscle-tendon unit properties of the quadriceps muscle, and mechanical performance after repeated sprint cycling at optimal and 70% of optimal cadence.

METHODS

Twenty recreational cyclists performed as first sprint performance cycling test and during subsequent sessions two repeated sprint cycling protocols at optimal and 70% of optimal cadence, in random order. The muscle-tendon unit outcome measures on the dominant leg included muscle thickness, fascicle length (Lf), pennation angle (θp), and stiffness for the rectus femoris (RF), vastus lateralis (VL), and vastus medialis muscle (VM) at baseline, immediately after repeated sprint cycling, and 1-h post-exercise.

RESULTS

The results showed an increase in muscle thickness and θp in RF, VL, and VM for both cadences from baseline to immediately after exercise. The Lf decreased in RF (both cadences), while stiffness decreased in RF, VL, and VM at optimal cadence, and in VL at 70% of optimal cadence from baseline to immediately after exercise.

CONCLUSION

The present study revealed that the alterations in muscle characteristics were more marked after repeated sprint cycling at optimal cadence compared with a lower cadence most likely as a result of higher load on the muscle-tendon unit at optimal cadence.

The effects of football juggling learning on executive function and brain functional connectivity

This study aimed to explore the relationship between motor skill learning and executive function (EF), with an emphasis on the potential effects of football juggling learning. A randomized controlled trial involving 111 participants aged 17-19 years was conducted. Participants were randomly assigned to either the football juggling learning (FJL) group or a control group. The FJL group underwent 70 sessions of football juggling learning, while the control group engaged in their normal daily activities without any exercise intervention during the same time frame. Both groups were assessed for EF performance and underwent functional magnetic resonance imaging (fMRI) scans before and after the experiment. The executive function test included three tasks, namely, inhibition, working memory, and shifting. The results showed significant improvement in inhibition and shifting in both groups, and the FJL group showed greater improvement in these aspects of EF compared to the control group. Additionally, in comparison to the control group, the FJL group exhibited increased functional connectivity within the frontal, temporal, and cerebellar regions from the pre-test to the post-test. Notably, enhanced functional connectivity between the right superior temporal gyrus (posterior division) and left cerebellum 6 was identified in the FJL group and was associated with improved EF performance induced by football juggling learning. These findings shed light on the potential causal relationship between motor skill learning, EF, and brain plasticity. Importantly, our study provides preliminary evidence supporting the use of motor skill learning, such as football juggling, as a potential avenue for cognitive enhancement.

Reliability of a semi-tethered front crawl sprint performance test in adolescent swimmers

This study aimed to evaluate the test-retest reliability of a sprint performance test with semi-tethered front crawl swimming to indirectly assess the current potential to perform at maximal anaerobic effort in adolescent swimmers. Eight adolescent swimmers participated in this study (gender: females (n = 4) aged 13.0 ± 0.8 years, body height 1.6 ± 0.0 m, body mass 50.1 ± 4.5 kg; and males (n = 4) aged 13.3 ± 1.3 years, body height 1.7 ± 0.1 m, body mass 59.0 ± 8.2 kg. The testing protocol consisted of two trials of 25 m semi-tethered front crawl swimming with maximal effort and with 1 kg resisted isotonic load. Velocity data were recorded automatically by the 1080 Sprint device for 15 m (between 3 m and 18 m). The Fast Fourier Transform algorithm filtered raw instantaneous swimming velocity data in distance (time) function. A third-degree polynomial was used to extract the individual velocity profile, from which the following variables were chosen for test-retest reliability and the assessment of sprint performance: ttrial15, vmax, vmin, tvto max, tvat max, Dto vmax, Dat vmax, fatigue index. Parameters such as vmax, vmin, and ttrial15 were estimated from swimming velocity profiles and considered as reliable. The CV showed low variance <5%; while ICC2,1 demonstrated respectively good (ICC2,1: 0.88), very good (ICC2,1: 0.95), and excellent (ICC2,1: 0.98) rate of relative reliability; and the Bland-Altman index revealed an acceptable agreement (LoA ≤5%) between two measurements. The sprint performance test based on semi-tethered front crawl swimming confirmed that ttrial15, vmax, and vmin were reliable variables to indirectly indicate a potential to perform the maximal anaerobic effort among adolescent swimmers. The evaluation of the swimming velocity profiles allows coaches to monitor the adaptive changes of performance during the training process.

Fatigue-induced Alterations of the Patellar Tendon in Elite Sprint Track Cyclists

This study aims to investigate morphological and mechanical properties and echogenicity of the patellar tendon (PT) after acute fatigue-induced alterations in sprint track cyclists. Fourteen elite track cyclists participated in this study. The exercise protocol consisted of three maximal start accelerations (over a distance of 62.5 m), one maximal start acceleration (at both 125 m and 250 m), and sprints from the standing start. Immediately after testing all measurements, PT stiffness and thickness were set at 5-10-15-20 mm distal from the apex of the patella and 5-10 mm proximal to the tibial tuberosity. CSA was set at proximal, middle, and distal, while echogenicity was at proximal and distal points. The results showed significant increases in PT stiffness at all reference points after start acceleration (p<0.001). PT thickness showed similar results for stiffness, except for location placed at TT-5 (p<0.001). CSA increased significantly in proximal, middle, and distal regions (p<0.001), while echogenicity of the tendon increased in proximal and distal regions (p<0.001) after start acceleration. Regional-dependent alterations of PT thickness and stiffness may be related to anatomical and physiological mechanisms due to acute isometric contraction in the initial phase of standing start. Tendon echogenicity might be also useful in monitoring tendon mechanical properties and defining acute fatigue-induced changes.

Multiple cryosauna sessions for post-exercise recovery of delayed onset muscle soreness (DOMS): a randomized control trial

The main goal was to investigate the effectiveness of cryosauna in preventing the development of delayed onset muscle soreness and to analyze the regenerative changes within muscles after acute fatigue-induced exercises. Thirty-one volunteers were assigned into two groups: 1) an intervention group that participated in cryostimulation after fatigue-induced exercise protocol (CRYO, n = 16) and a control group that performed fatigue-induced exercise protocol, but without any intervention (CONT, n = 15). Main outcome measures include at baseline: blood sample testing (leukocyte content, myoglobin concentration, and creatine kinase activity) and muscle stiffness of lower extremity; immediately after (stiffness), and 24-48-72-96 h post-exercise (blood samples and stiffness). Both groups performed an exercise-induced muscle damage protocol based on repeated countermovement jumps (10 sets, 10 repetitions). The CRYO group underwent a cryosauna (temperature: -110°C, time: 1.5 min per session) intervention during four sessions (i.e., immediately after, 24-48-72 h post-exercise). Leukocyte content was significantly greater 24-48-72 h after exercise in CONT, compared with the CRYO group (p ≤ 0.05 for all), while creatine kinase activity was greater 24-48-96 h in CONT, compared with the CRYO group (p ≤ 0.05 for all). Muscle stiffness increased significantly in rectus femoris, tibialis anterior, and fibula muscle after 48 h post-exercise (p ≤ 0.05 for all), as well as in tibialis anterior and fibula after 72 h post-exercise (p ≤ 0.05 for all) in the CRYO group. Multiple cryosauna was an effective recovery strategy that reduced blood biomarkers and muscle stiffness after exercise-induced muscle damage. Moreover, the development of delayed onset muscle soreness, expressed by a greater muscle stiffness post-exercise, was attenuated to the first 48 h.

Track cycling sprint sex differences using power data

Objectives

Currently, there are no data on sex differences in the power profiles in sprint track cycling. This cross-section study analyses retrospective data of female and male track sprint cyclists for sex differences. We hypothesized that women would exhibit lower peak power to weight than men, as well as demonstrate a different distribution of power durations related to sprint cycling performance.

Design

We used training, testing, and racing data from a publicly available online depository (www.strava.com), for 29 track sprint cyclists (eight women providing 18 datasets, and 21 men providing 54 datasets) to create sex-specific profiles. R² was used to describe model quality, and regression indices are used to compare watts per kilogram (W/kg) for each duration for both sexes against a 1:1 relationship expected for 15-s:15-s W/kg.

Results

We confirmed our sample were sprint cyclists, displaying higher peak and competition power than track endurance cyclists. All power profiles showed a high model quality (R² ≥ 0.77). Regression indices for both sexes were similar for all durations, suggesting similar peak power and similar relationship between peak power and endurance level for both men and women (rejecting our hypothesis). The value of R² for the female sprinters showed greater variation suggesting greater differences within female sprint cyclists.

Conclusion

The main finding shows female sprint cyclists in this study have very similar relationships between peak power and endurance power as men. Higher variation in W/kg for women in this study than men, within these strong relationships, indicates women in this study, had greater inter-athlete variability, and may thus require more personalised training. Future work needs to be performed with larger samples, and at different levels to optimize these recommendations.

Functional and morphological changes in shoulder girdle muscles after repeated climbing exercise

This study aimed to investigate the acute effect of repeated climbing actions on functional and morphological measures of the shoulder girdle. Fifteen male indoor climbers participated in this study. All the climbers declared route level 6a+, as the best climbing grade (French climbing grade scale). Functional (range of motion - ROM and muscle strength), and morphological measurements (muscle/tendon stiffness and thickness) after a repeated climbing exercise protocol were analysed. The ROM and muscle strength showed significant decreases from baseline to Immediate-Post (IA) as well as significant increases from IA to 1 h-Post for all movements (p ≤ .001 for all). Muscle stiffness showed significant increases from baseline to IA after as well as significant decreases from IA to 1 h-Post for all muscles (p ≤ .001 for all). However, the thickness showed significant increases from baseline to IA for supraspinatus tendon and muscle thickness and occupation ratio (p ≤ .001 for all), while a significant decrease was observed in acromiohumeral distance (p ≤ .001). Significant decreases from IA to 1 h-Post were found for muscles/tendons and occupation ratio (p ≤ .001 for all), while a significant increase for AHD (p ≤ .001). Our data demonstrated acute alterations in tendon thickness due to acute signs of implement symptom in climbers.

Power-duration relationship comparison in competition sprint cyclists from 1-s to 20-min. Sprint performance is more than just peak power

Current convention place peak power as the main determinant of sprint cycling performance. This study challenges that notion and compares two common durations of sprint cycling performance with not only peak power, but power out to 20-min. There is also a belief where maximal efforts of longer durations will be detrimental to sprint cycling performance. 56 data sets from 27 cyclists (21 male, 6 female) provided maximal power for durations from 1-s to 20-min. Peak power values are compared to assess the strength of correlation (R2), and any relationship (slope) across every level. R2 between 15-s- 30-s power and durations from 1-s to 20-min remained high (R2 ≥ 0.83). Despite current assumptions around 1-s power, our data shows this relationship is stronger around competition durations, and 1-s power also still shared strong relationships with longer durations out to 20-min. Slopes for relationships at shorter durations were closer to a 1:1 relationship than longer durations, but closer to long-duration slopes than to a 1:1 line. The present analyses contradicts both well-accepted hypotheses that peak power is the main driver of sprint cycling performance and that maximal efforts of longer durations out to 20-min will hinder sprint cycling. This study shows the importance and potential of training durations from 1-s to 20-min over a preparation period to improve competition sprint cycling performance.

Stiffness and thickness of the upper trapezius muscle increase after repeated climbing bouts in male climbers

Background

Indoor climbing involves overloading the shoulder girdle, including the rotator cuff and upper trapezius muscles. This on the field study aimed to investigate the effects of repeated climbing bouts on morphological and mechanical measures of the upper trapezius muscle.

Materials and Methods

Fifteen experienced male climbers participated in the study. Rate of perceived exertion (RPE), blood lactate concentration ([La^-]_b), and stiffness and thickness over four points of the upper trapezius were assessed before and after a repeated climbing exercise. The procedure for the climbing exercise consisted of five climbs for a total time of 5-minutes per climb, followed by a 5-minute rest.

Results

The analysis showed an increase from baseline to after the 3rd climb (p ≤ 0.01) for RPE and after the 5th climb for [La^-]_b (p ≤ 0.001). Muscle stiffness and thickness increased at all points (1-2-3-4) after the 5th climb (p ≤ 0.01). We found spatial heterogeneity in muscle stiffness and thickness; muscle stiffness was the highest at Point 4 (p ≤ 0.01), while muscle thickness reached the highest values at points 1-2 (both p ≤ 0.01). Moreover, the analysis between the dominant and non-dominant shoulder showed greater stiffness after the 1^st climb at Point 1 (p = 0.004) and after the 5^th climb at Point 4 (p ≤ 0.001).

Conclusions

For muscle thickness, the analysis showed significant changes in time and location between the dominant and the non-dominant shoulder. Bilateral increases in upper trapezius muscle stiffness and thickness, with simultaneous increases in RPE and blood lactate in response to consecutive climbs eliciting fatigue.

Bibliometric analysis of research trends of physical activity intervention for autism spectrum disorders

Autism spectrum disorder (ASD) is a neurodevelopmental disorder characterized by social impairment, restricted interests, and repetitive stereotyped behaviors. At present, its pathogenesis has not been fully understood. Various methods are used for clinical treatment and intervention, among which physical activity (PA) intervention also has an obvious effect. This study has used bibliometric methods and visual analysis methods to analyze 885 studies of PA intervention in ASD from 2003 to 2022 in the Web of Science (WoS) database in order to provide theoretical support for the follow-up research on the effect of PA with ASD. The main findings of this study are as follows. First, the literature on PA interventions in ASD research showed a growing trend. The leading institution in this field is the University of Delaware, forming a core group of authors represented by authors such as Sean Healy and Carol Curtin et al. Second, the research focus of this research area mainly includes PA interventions for children and adolescents with ASD. PA can improve symptoms such as stereotyped behaviors and motor function in patients with ASD as well as can reduce childhood obesity rates and improve quality of life. Third, skill, youth, prevalence, and meta-analysis systematic reviews were found. It is the long-term concern and focus of researchers. In conclusion, the current research is only a short-term analysis, and it is not possible to verify the long-term effect; thus, future data analysis should evaluate and explore the long-term effects of PA interventions on ASD including cohort and longitudinal study types focused on the rehabilitation of patients with ASD. Moreover, testing the sustainability of benefits for children with ASD and constructing a multidimensional exercise integrated intervention model are the main directions for future research in this field.

Ultrasound imaging of patellar tendon thickness in elite sprint track cyclists and elite soccer players: An intra-rater and inter-rater reliability study

The goal of our study was to investigate the relative and absolute intra-rater and inter-rater reliability of ultrasound assessment of patellar tendon (PT) thickness assessed over four locations, in track cyclists and soccer players. Fifteen male elite track cyclists and 15 male elite soccer players participated. Tendon thickness was measured over 4 locations placed at 5-10-15-20 mm inferior to the apex of the patella by two experienced examiners. Each examiner took two US images for the test measurements with a 10-min rest period. After a 30-min period, the subjects underwent a retest measurements that were also repeated 1-week after. A two-way analysis of variance revealed a significant group x location interaction on PT thickness for Examiner 1 (p = .001, η² = .81) and Examiner 2 (p = 0.001, η² = 0.78). Intra-rater reliability ranged from good to excellent (ICC_2,k ≥ 0.75), whereas inter-rater reliability was good (ICC_2,k ≥ 0.75) in both groups. Ultrasonographic assessment of PT was found to be a reliable method to assess tendon thickness. The middle location of the PT (corresponding to 15 and 20 mm) can be considered the most reliable spot to measure PT thickness. The PT thickness was larger among track cyclists than soccer players, with larger differences over the distal location (15 mm). Ultrasonographic assessment of PT was found to be a reliable method to assess tendon thickness. The middle location of the PT corresponding to 15 mm and 20 mm can be considered the most reliable area to measure PT thickness.

Quadriceps and Patellar Tendon Thickness and Stiffness in Elite Track Cyclists: An Ultrasonographic and Myotonometric Evaluation

Track cyclists are required to perform short- and long-term efforts during sprint and endurance race events, respectively. The 200 m flying sprint races require maximal power output and anaerobic capacity, while the 4,000 m pursuit cyclists demand a high level of aerobic capacity. Our goal was to investigate spatial changes in morphological and mechanical properties displayed using 3D topographical maps of the quadriceps muscle and tendons after 200 m flying start and 4,000 m individual pursuit race in elite track cyclists. We hypothesized a non-uniform distribution of the changes in the quadriceps muscle stiffness (QM_stiff), and acute alterations in quadriceps tendon (QT_thick) and patellar tendon (PT_thick) thickness. Fifteen men elite sprint and 15 elite men endurance track cyclists participated. Sprint track cyclists participated in a 200 m flying start, while endurance track cyclists in 4,000 m individual pursuit. Outcomes including QT_thick (5–10–15 mm proximal to the upper edge of the patella), PT_thick (5–10–15–20 mm inferior to the apex of the patella)—using ultrasonography evaluation, QM_stiff, and quadriceps tendon stiffness (QT_stiff) were measured according to anatomically defined locations (point 1–8) and patellar tendon stiffness (PT_stiff)—using myotonometry, measured in a midway point between the patella distal and the tuberosity of tibial. All parameters were assessed before and after (up to 5 min) the 200 m or 4,000 m events. Sprint track cyclists had significantly larger QT_thick and PT_thick than endurance track cyclists. Post-hoc analysis showed significant spatial differences in QM_stiff between rectus femoris, vastus lateralis, and vastus medialis in sprint track cyclists. At before race, sprint track cyclists presented significantly higher mean QT_thick and PT_thick, and higher QM_stiff and the QT_stiff, as compared with the endurance track cyclists. The observed changes in PT_Thick and QT_Thick were mostly related to adaptation-based vascularity and hypertrophy processes. The current study suggests that assessments using both ultrasonography and myotonometry provides crucial information about tendons and muscles properties and their acute adaptation to exercise. Higher stiffness in sprint compared with endurance track cyclists at baseline seems to highlight alterations in mechanical properties of the tendon and muscle that could lead to overuse injuries.

Fatigue-Induced Scapular Dyskinesis in Healthy Overhead Athletes

Alterations of scapular kinematics affect the whole kinematic chain, potentially leading to the impingement syndrome. This is crucial in overhead sports, where athletes perform frequent and quick upper limb actions. In this manuscript, we aimed to assess the extent to which fatigue alters scapulo-thoracic and scapulo-humeral ranges of motion (RoM), as well as scapulo-humeral movement onset during different upper limb actions. Twenty-four young healthy males aged 22 ± 2 years (height: 1.82 ± 0.06 m, body mass: 78.0 ± 7.8 kg) performed three movements (upper limb elevation, scapular-plane abduction, and intra-extra rotation) before and after an isokinetic fatigue protocol (upper limb intra/extra rotation, 32 repetitions at 120 degrees/s). Pre vs. post fatigue RoM of humeral elevation and rotation, scapular retraction/protraction, and rotation and tilt were computed. Humerus-scapula movement delay was also determined. Humerus elevation range reduced during intra/extra humerus rotation in fatigued conditions (p = 0.006). Scapular tilt RoM increased after the fatigue protocol (p = 0.063, large effect). Humerus-scapular movement onset delay reduced in fatigued conditions of about 80 ms (p < 0.001, large effect). In sum, fatigued intra/extra upper limb rotators altered the scapulohumeral rhythm, and joints RoM in movements outside the scapular plane. Rather, movements close to the scapular plane were less prone to fatigue-induced alterations.

Shoulder tendon characteristics in disabled swimmers in high functional classes - Preliminary report

OBJECTIVE

To characterize disabled swimmers in comparison to an able-bodied swimmers for (1) supraspinatus tendon thickness, (2) subacromial space and (3) occupation ratio.

DESIGN

Cross-Sectional Study.

SETTING

Research laboratory.

PARTICIPANTS

Disabled swimmers with upper (DSw-Upper) (n = 8) and lower (DSw-Lower) (n = 7) extremity disorders. The DSw-Upper were classified in sports class S7-S8, while DSw-Lower in S9-S10. The control group had 15 able-bodied swimmers.

MAIN OUTCOME MEASURES

Ultrasound images of (1) supraspinatus tendon in short axis and long axis, (2) subacromial space, and (3) occupation ratio.

RESULTS

A thicker supraspinatus tendon in short axis was observed in DSw-Upper versus C-Sw (p = 0.012) and DSw-Upper versus DSw-Lower (p = 0.018); and in long axis for DSw-Upper versus CSw (p = 0.0001), and DSw-Upper versus DSw-Lower (p = 0.002). There was a greater occupation ratio in DSw-Upper versus DSw-Lower in short axis (p = 0.013) and long axis (p = 0.035).

CONCLUSIONS

The present study showed a thicker supraspinatus tendon and greater occupation ratio with the tendon occupying more of the subacromial space that may predispose upper extremity disabled swimmers to tendon disorders such as subacromial impingement syndrome. Ultrasound examination can be used to assess shoulder tendon characteristics and the relationship to the subacromial space, to determine potential for injury and training load monitoring.

Effect of short-term cold-water immersion on muscle pain sensitivity in elite track cyclists

OBJECTIVE

To determine the effect of short-term cold-water immersion (CWI) on muscle pain sensitivity after maximal anaerobic power training in track cyclists.

DESIGN

Repeated measures.

SETTING

University Laboratory.

PARTICIPANTS

12 elite sprint track cyclists (age 24,75 ± 4,23 years).

MAIN OUTCOME MEASURES

PPT measurements were made on dominant lower extremity (right) in 20 reference points, including anterior thigh muscles, posterior thigh muscles and posterior cuff muscles. PPT levels were measured: 1) before workout, 2) immediately after workout, but before CWI 3) 1 h after CWI and 4) 12 h after CWI. Mean PPT values for each muscle group per participant were calculated for further statistical analysis.

RESULTS

The average PPT for anterior thigh muscles decreased significantly after effort (p = 0.001) and increased significantly 1 h after CWI (p = 0.048). In posterior thigh muscles PPT decreased significantly after effort (p = 0.014) and increased significantly 1 h and 12 h after CWI (p = 0.045 and p = 0.25 respectively). However, in posterior cuff muscles PPT decreased only after effort (p = 0.001).

CONCLUSIONS

Short-term repeated sprint exercise appears to affect PPT in track cyclists. This study have reported that CWI in 5 °C for 5 min have had a beneficial effect in minimizing PPT 1 h post repeated maximal sprint training.

Foot mechanics in young women are altered after walking in high-heeled shoes

PURPOSE

Nowadays, fashion has caused that many young women are wearing high-heeled shoes. Therefore, the aim of this study was to examine the effects of long-term walking in high-heeled shoes on the foot mechanics during barefoot gait.

METHODS

Forty-three young women (22 ± 2.1 years) divided into two groups participated in this retrospective cohort study. The first group was composed of women who frequently wear high-heeled footwear. The second, infrequent wearers group, consisted of women who preferred flat-heeled shoes. Measurements of gait parameters were recorded for barefoot gait. A motion analysis system and two force plates were used in order to evaluate the lower-limb rocker mechanism, transverse foot arch height and parameters of ground reaction force.

RESULTS

Walking in high-heeled shoes modified barefoot foot mechanics, which manifested itself in a shorter duration (by ca. 4%) of the first and second rocker and a significantly longer duration (by 5%) of the third rocker phase as well as a substantial reduction in height of the transverse foot arch (by around 50%) in women habitually walking in high-heeled shoes. A significantly shorter relative duration of the third rocker (44.3% of cycle time) and greater value of the vertical component of ground reaction force (114.7% BW) in the third rocker phase were found in the group of women habitually walking in high-heeled shoes.

CONCLUSIONS

The mechanism of foot rolling, with flattened foot arch, and significantly higher values of the vertical component of ground reaction force and shorter time might lead to overload in lowerlimb joints in young women.

Functional connectivity between core and shoulder muscles increases during isometric endurance contractions in judo competitors

PURPOSE

The aim of this study was to assess the surface electromyogram (SEMG) changes within and between muscles of the torso and shoulder region during static endurance contraction in elite judokas. We hypothesized an increased functional connectivity of muscles from the shoulder and torso regions during sustained isometric contraction.

METHODS

Twelve healthy, right-handed judo competitors participated in the study. The SEMG signals from the dominant trapezius (upper, middle and lower part), deltoideus anterior, serratus anterior, and pectoralis major muscles were recorded during isometric endurance contraction consisting of bilateral arm abduction at 90°. The normalized mutual information (NMI) was computed between muscle pairs as an index indicating functional connectivity.

RESULTS

The NMIs increased significantly during endurance test for 10 of the 15 muscle pairs (P < 0.001).

CONCLUSION

We concluded that the increases in NMIs highlighted functional changes in the interplay between core and shoulder muscles during an endurance contraction in elite judokas.

[Ultra-small superparamagnetic iron oxide particles: the signal behavior and relaxation times of the bone marrow after repeated i.v. application in the pig model at 1.5 tesla]

PURPOSE

Evaluation of the influence of an iron-containing MR contrast agent on the signal behaviour and the relaxation time of the bone marrow at 1.5 tesla after repeated doses.

ANIMALS AND METHODS

14 pigs received i.v. on days 1, 9, and 15 ultra-small (core diameter 6-8 nm) superparamagnetic iron oxide particles at doses of 20 (low dose = LD) or 200 mumol/kg body weight (high dose = HD).

RESULTS

Following the first administration a dose-independent reduction in the bone-marrow signal intensity in the T2-weighted gradient-echo sequence (FFE) was observed together with a reduction in the T1 and T2 relaxation times. Following the second application there were no further signal-reductions in the HD-group; in contrast, there was a signal reduction in the LD-group, made possible by a signal recovery in the meantime. On the other hand, the relaxation times T1 and T2 were shortened after each administration of contrast medium.

CONCLUSION

Nano-SIPS result at both doses in a signal reduction in the bone marrow. Only in the LD-group may repeated examinations with new contrast agent offer diagnostically sufficient images. Relaxometry shows a shortening of T1 as well as T2. This effect could be summed up after repeated doses. Almost no iron remained in the medullary space three weeks after i.v. administration of the contrast agent, which suggests mobilization and metabolization.

The cytotoxicity of mafosfamide on G-CSF mobilized hematopoietic progenitors is reduced by SH groups of albumin--implications for further purging strategies

The efficacy of mafosfamide purging depends on factors like incubation time, drug and erythrocyte concentration. To determine the influence of protein-bound SH groups in the incubation medium, the cytotoxicity of mafosfamide on G-CSF mobilized CD34+/- cells was evaluated by short-term culture assays and drug concentration measurements. 100 micromol/ml mafosfamide was incubated for 30 min in five buffers (PBS, PBS with 1%, 5% and 10% BSA and plasma). The mean calculated areas under the concentration-time curves (AUC) were 2489 +/- 198, 1561 +/- 286, 976 +/- 201, 585 +/- 62 and 605 +/- 196 micromol/l/min. The mean reductions of CFU-GM growth were 79.4%, 73.0%, 62.5%, 30.3%, 6.2% respectively. Similar results were obtained for BFU-E. Regression analysis showed a good correlation between cytotoxicity and AUCs (CFU-GM: r = 0.8195; BFU-E: r = 0.8207). This effect is well explained by the different concentrations of SH moieties in the incubation medium resulting in a higher drug binding capacity. The profound difference between AUCs and CFU-GMs in plasma and 10% BSA cannot be explained by the quantity of SH-groups. It is probably due to an additional enzymatic drug degeneration by the 3'-5'exonuclease subsite of plasma DNA polymerase. In conclusion, the concentration of albumin-associated SH groups strongly influences the cytotoxicity of mafosfamide. It has to be considered as a new and important aspect in ex vivo bone marrow purging.