Effects of passive ankle dorsiflexion stiffness on ankle mechanics during drop landings

ObjectivesVertical landing tasks strain the Achilles tendon and plantar-flexors, increasing acute and overuse strain injury risk. This study aimed to determine how passive ankle dorsiflexion stiffness affected ankle mechanics during single limb drop landings at different vertical descent velocities.DesignCross-sectional study.MethodsPassive ankle dorsiflexion stiffness and passive weight-bearing dorsiflexion range of motion (DROM) were quantified for 42 men. Participants were then grouped as having low (LPS: 0.94 ± 0.15 Nm °^?1; n = 16) or high (HPS: 2.05 ± 0.36 Nm °^?1; n = 16; p < 0.001) passive ankle dorsiflexion stiffness. Three-dimensional ankle joint kinematics was quantified while participants performed drop landings onto a force platform at two vertical descent velocities (slow: 2.25 ± 0.16 m s^?1; fast: 3.21 ± 0.17 m s^?1).ResultsAlthough affected by landing velocity, there were no significant effects of passive ankle dorsiflexion stiffness, nor any significant ankle dorsiflexion stiffness × vertical descent velocity interactions on any outcome variables characterising ankle mechanics during drop landings. Furthermore, there was no significant difference between the groups for passive weight-bearing DROM (LPS: 43.9 ± 4.1°; HPS: 42.5 ± 5.7°), indicating that the results were not confounded by between-group differences in ankle range of motion.ConclusionsNeither high nor low passive ankle dorsiflexion stiffness was found to influence ankle biomechanics during drop landings at different descent velocities. Landing strategies were moderated more by the demands of the task than by passive ankle dorsiflexion stiffness, indicating that passive ankle dorsiflexion stiffness may not affect plantar-flexor strain during a drop landing.     

The influence of ankle dorsiflexion and self-reported patient outcomes on dynamic postural control in participants with chronic ankle instability

We investigated the influence of ankle dorsiflexion range of motion (DF-ROM) and self-reported patient outcomes on dynamic postural control assessed with the Star Excursion Balance Test (SEBT) in individuals with chronic ankle instability (CAI). Twenty-nine participants with self-reported CAI volunteered. The primary outcome measurements were categorized into clinician-and patient-generated. Clinician-generated outcome measurements included anterior (SEBT-A), posteriormedial (SEBT-PM) and posteriorlateral (SEBT-PL) reach distances (cm) normalized by leg length (cm) of the SEBT, maximum weight-bearing dorsiflexion (WB-DF) (cm), and open-chain DF-ROM (°). Self-reported patient-generated outcome measures included the foot and ankle ability measure and the level of perceived pain, stiffness, stability, and function of their involved ankle on a 10-cm visual analog scale (VAS). Pearson product moment correlations were used to examine the relationship of the SEBT performances with DF-ROM and self-reported patient outcome measures. A multiple linear regression was performed to determine the influence of patient- and clinician-generated measures on the SEBT. SEBT-A performance was significantly and fairly correlated with WB-DF (r = 0.410, p = 0.014), perceived ankle stiffness (r = 0.477, p = 0.014), and open-chain DF-ROM (r = 0.404, p = 0.015). The strongest predictor of the variance in SEBT-A was the combination of the variance in WB-DF and VAS-stiffness (R² = 0.348, p = 0.004). There were no significant correlations with the SEBT-PM and SEBT-PL. WB-DF and VAS-stiffness may represent targets for intervention that need to be addressed to produce the best outcome in participants with CAI when altered dynamic postural control is detected on the SEBT-A.     

Fibular taping does not influence ankle dorsiflexion range of motion or balance measures in individuals with chronic ankle instability

ObjectivesTo determine the effects of fibular taping on ankle dorsiflexion range of motion (ROM) and dynamic balance in individuals with chronic ankle instability (CAI).DesignSingle-blind, randomized crossover.MethodsTwenty-three individuals (age = 23.4 ± 2.5 years, height = 171.6 ± 12.4 cm, mass = 71.5 ± 13.1 kg) with CAI were allocated to either a fibular taping intervention or sham taping intervention (tape applied without tension) over the course of two visits. Weight-bearing ankle dorsiflexion ROM and components of the Star Excursion Balance Test (SEBT) were measured before and after intervention.ResultsThere was not a significant change in ankle dorsiflexion ROM when comparing the taping interventions (F_1,43 = 1.03, P = .32), but both interventions resulted in a small increase (F_1,43 = 8.07, P = .007) in dorsiflexion ROM (pre = 36.7° ± 6.9°, post = 37.7° ± 6.2°). This increase in ROM did not exceed the established minimal detectable change for dorsiflexion ROM. Fibular taping with tension produced an increase (F_1,41 = 5.84, P = .02) (pre = 69.0 ± 9.1%, post = 70.6 ± 8.6%) in posterolateral reach distance when compared to taping without tension (pre = 72.7 ± 11.0%, post = 71.4 ± 9.6%), but this increase did not exceed the established minimal detectable change. There was not a significant change in dynamic balance between groups for the anterior (F_1,41 = 2.33, P = .14) and posteromedial (F_1,41 = .41, P = .53) reach directions.ConclusionsAlthough small changes in ankle dorsiflexion ROM and posterolateral reach distances were observed, these changes did not exceed established minimal detectable change values for these measures. These results suggest that the benefits of fibular taping are not related to an increase in ankle dorsiflexion ROM or dynamic balance.     

Differences in knee adduction moment between healthy subjects and patients with osteoarthritis depend on the knee axis definition

ObjectiveThis study, firstly, investigates the effect of using an anatomical versus a functional axis of rotation (FAR) on knee adduction moment (KAM) in healthy subjects and patients with knee osteoarthritis (KOA). Secondly, this study reports KAM for models with FAR calculated using weight-bearing and non-weight-bearing motion.DesignThree musculoskeletal models were created using OpenSim with different knee axis of rotation (AR): transepicondylar axis (TEA); FAR calculated based on SARA algorithm using a weight-bearing motion (wFAR) and a non-weight-bearing motion (nwFAR). KAM were calculated during gait in fifty-nine subjects (n = 20 healthy, n = 16 early OA, n = 23 established OA) for all models and groups.ResultsSignificant differences between the three groups in the first peak KAM were found when TEA was used (p = 0.038). However, these differences were no longer present when using FAR. In subjects with established OA, KAMs were significantly reduced when using nwFAR compared to TEA models but also compared to wFAR models.ConclusionThe presence of excessive KAM in subjects with established KOA showed to be dependent on the definition of the AR: anatomical versus functional. Therefore, caution should be accounted when comparing KAM in different studies on KOA patients. In patients with end-stage knee OA where increased passive knee laxity is likely to exist, the use of weight-bearing motions should be considered to avoid increased variability in the location and orientation of a FAR obtained from activities with only limited joint loading.     

Normalizing considerations for time to stabilization assessment

ObjectivesBecause of the growing use of time to stabilization (TTS) and similar measures with single-limb landings in lower extremity research, it is important to determine if the task performance needs to be normalized further. The purpose of this study was to compare TTS of healthy participants using a standardized versus a normalized horizontal jumping distance.DesignCrossover study.MethodsTwenty-one healthy participants performed single landings using two horizontal jumping distances: standardized (70 cm) and normalized (leg length). Resultant vector TTS (RVTTS) was calculated to represent the dynamic stability performance.ResultsFor RVTTS, the participants took significantly longer to stabilize when using the normalized jumping distance (1.997 ± 0.181 s) compared with the standardized jumping distance (1.921 ± 0.126 s) (t = 5.134; p < 0.001; power = 0.65). RVTTS during the normalized jumping distance was more strongly correlated with leg length (r = 0.628; p = 0.002) than during the standardized jumping distance (r = 0.563; p = 0.008).ConclusionsNormalizing the horizontal jumping distance during the single-limb jumping task creates a performance decrement in RVTTS among healthy participants. Because dynamic stability measured with RVTTS when jumping a normalized distance is more strongly correlated with leg length than when jumping a standardized jumping distance, researchers using this task and analysis may want to consider using this additional normalizing step in future investigations.     

Dorsiflexion and dynamic postural control deficits are present in those with chronic ankle instability

ObjectivesTo determine if differences in weight-bearing ankle dorsiflexion range of motion (DFROM) and Star Excursion Balance Test (SEBT) reach distances were present between participants with chronic ankle instability (CAI) and healthy individuals. A secondary objective was to re-examine the relationship between these measures in participants with and without CAI.DesignCase–control.MethodsThirty participants with CAI were matched to 30 healthy participants. All participants performed maximum reach in the anterior, posteromedial and posterolateral directions of the SEBT; as well as, the Weight-Bearing Lunge Test (WBLT) to measure DFROM. Dependent variables included maximal DFROM (cm) and normalized SEBT reach distances (%). Independent t-tests were used for group comparisons (a priori p ≤ 0.05). Simple-linear regression examined the relationship between the WBLT and each SEBT direction.ResultsSignificant differences were detected between groups for the WBLT (CAI: 10.73 ± 3.44 cm, healthy: 12.47 ± 2.51 cm; p = 0.03) and anterior reach distance (CAI: 76.05 ± 6.25%, healthy: 80.12 ± 5.88%; p = 0.01). No differences were identified in posteromedial or posterolateral (ps > 0.70) reach. The WBLT had a significant moderate correlation to anterior reach in both groups (ps < 0.05) but was not significantly correlated to posteromedial or posterolateral reach distance (ps > 0.70).ConclusionsThe results indicate that participants with CAI demonstrated less DFROM and anterior SEBT reach distance compared to health controls. Additionally, both groups demonstrated similar correlations between WBLT and SEBT performance. These findings suggest that participants with CAI have alterations in ankle motion which may negatively influence dynamic postural control; however, the relationship between WBLT and SEBT performance is consistent in those with and without CAI.     

Physiological factors determining downhill vs uphill running endurance performance

ObjectivesRecent studies investigated the determinants of trail running performance (i.e., combining uphill (UR) and downhill running sections (DR)), while the possible specific physiological factors specifically determining UR vs DR performances (i.e., isolating UR and DR) remain presently unknown. This study aims to determine the cardiorespiratory responses to outdoor DR vs UR time-trial and explore the determinants of DR and UR performance in highly trained runners.DesignRandomized controlled trial.MethodsTen male highly-trained endurance athletes completed 5-km DR and UR time-trials (average grade: ±8%) and were tested for maximal oxygen uptake, lower limb extensor maximal strength, local muscle endurance, leg musculotendinous stiffness, vertical jump ability, explosivity/agility and sprint velocity. Predictors of DR and UR performance were investigated using correlation and commonality regression analyses.ResultsRunning velocity was higher in DR vs UR time-trial (20.4 ± 1.0 vs 12.0 ± 0.5 km·h^?1, p < 0.05) with similar average heart rate (95 ± 2% vs 94 ± 2% maximal heart rate; p > 0.05) despite lower average V?O₂ (85 ± 8% vs 89 ± 7% V?O_2max; p < 0.05). Velocity at V?O_2max (vV?O_2max) body mass index (BMI) and maximal extensor strength were significant predictors of UR performance (r² = 0.94) whereas vV?O_2max, leg musculotendinous stiffness and maximal extensor strength were significant predictors of DR performance (r² = 0.84).ConclusionsFive-km UR and DR running performances are both well explained by three independent predictors. If two predictors are shared between UR and DR performances (vV?O_2max and maximal strength), their relative contribution is different and, importantly, the third predictor appears very specific to the exercise modality (BMI for UR vs leg musculotendinous stiffness for DR).     

The potential of multi-slice computed tomography based volumetry for demonstrating reverse remodeling induced by cardiac resynchronization therapy

BackgroundMulti-slice computed tomography (MSCT) was proved to provide precise cardiac volumetric assessment. Cardiac resynchronization therapy (CRT) is an effective treatment for selected patients with heart failure and reduced ejection fraction (HFREF). In HFREF patients we investigated the potential of MSCT based wall motion analysis in order to demonstrate CRT-induced reversed remodeling.MethodsBesides six patients with normal cardiac pump function serving as control group seven HFREF patients underwent contrast enhanced MSCT before and after CRT. Short cardiac axis views of the left ventricle (LV) in end-diastole (ED) and end-systole (ES) served for planimetry. Pre- and post-CRT MSCT based volumetry was compared with 2D echo. To demonstrate CRT-induced reverse remodeling, MSCT based multi-segment color-coded polar maps were introduced.ResultsWith regard to the HFREF patients pre-CRT MSCT based volumetry correlated with 2D echo data for LV-EDV (MSCT 278.3 ± 75.0 mL vs. echo 274.4 ± 85.6 mL) r = 0.380, p = 0.401, LV-ESV (MSCT 226.7 ± 75.4 mL vs. echo 220.1 ± 74.0 mL) r = 0.323, p = 0.479 and LV-EF (MSCT 20.2 ± 8.8% vs. echo 20.0 ± 11.9%) r = 0.617, p = 0.143. Post-CRT MSCT correlated well with 2D echo: LV-EDV (MSCT 218.9 ± 106.4 mL vs. echo 188.7 ± 93.1 mL) r = 0.87, p = 0.011, LV-ESV (MSCT 145 ± 71.5 mL vs. echo 125.6 ± 78 mL) r = 0.84, p = 0.018 and LV-EF (MSCT 29.6 ± 11.3 mL vs. echo 38.6 ± 14.6 mL) r = 0.89, p = 0.007. There was a significant increase of the mid-ventricular septum in terms of absolute LV wall thickening of the responders (pre 0.9 ± 2.1 mm vs. post 3.3 ± 2.2 mm; p < 0.0005).ConclusionMSCT based volumetry involving multi-segment color-coded polar maps offers wall motion analysis to demonstrate CRT-induced reverse remodeling which needs to be further validated.     

Malignant breast tumours: Correlation of apparent diffusion coefficient values using diffusion-weighted images and dynamic contrast-enhancement ratio with histologic grading

PurposeTo evaluate the correlation of the apparent diffusion coefficient (ADC) using diffusion weighted imaging (DWI) and early/delayed enhancement (E/D) ratio using dynamic contrast enhanced magnetic resonance imaging (DCE-MRI) with histological grading in malignant breast lesions.Material and methodsThirty-one women with 34 histopathologically proved malignant breast lesions underwent MRI within 2 weeks prior to surgery. MRI examination included T1 and T2 W sequences, DWI and DCE-MRI. ADC values and E/D ratios are correlated with the histological grades.ResultsThe mean ADC of the malignant lesions was 0.85 ± 0.12 × 10^?3 mm²/s. The mean ADC values of grade I, II and III were 0.96 ± 0.12 × 10^?3 mm²/s, 0.87 ± 0.07 × 10^?3 mm²/s and 0.75 ± 0.12 × 10^?3 mm²/s, respectively. Tumours with higher grade showed significantly lower ADC value (p = 0.0001) compared with lower grade and there is an inverse correlation between ADC value and histological grade (r = ?0.62, p-value = 0.0001). The mean E/D ratio for grade I, II and III tumours were 0.98 ± 0.04, 1.01 ± 0.05 and 1.07 ± 0.08, respectively. Tumours with higher grade showed significantly higher E/D ratio (p = 0.005) compared with lower grade and there was a direct correlation between E/D ratio and histological grade (r = 0.44, p = 0.008).ConclusionDWI is a useful diagnostic parameter with significantly higher correlation with the histological grade of breast cancer than DCE MRI, which is an important factor for proper treatment selection.     

Tibial rotation in running: Does rearfoot adduction matter?

ObjectiveTo quantify the magnitude of global rearfoot motion, in particular, rearfoot adduction and to investigate its relationship to tibial rotation.DesignOne hundred and four participants ran barefoot on an Ethylene Vinyl Acetate (EVA) foam. Global range of motion values for the shank, rearfoot and medial metatarsal segment as well as foot motion within the transverse plane were determined using an optoelectric motion capture system. Relationships between parameters were assessed using partial correlation analysis.ResultsGlobal rearfoot adduction amounts to 6.1° (±2.7). Furthermore global rearfoot adduction and rearfoot eversion were significantly related to internal tibial rotation (partial correlation: r = 0.37, p < 0.001 and r = −0.24, p = 0.015, respectively). Furthermore, a strong relationship between rearfoot adduction and transverse within foot motion (r = −0.65, p < 0.001) was found.ConclusionNext to rearfoot eversion, rearfoot adduction may be also important to the understanding of ankle joint coupling. Controlling rearfoot adduction and transverse within foot motion may be a mechanism to control excessive tibial rotation.     

A comprehensive evaluation of the variation in ankle function during gait in children and youth with Charcot–Marie–Tooth disease

A better understanding of gait dysfunction for children and youth with Charcot–Marie–Tooth (CMT) will assist in developing appropriate treatments and understanding prognosis for ambulation. The purpose of this retrospective study was to document the typical gait patterns in children and youth (12 ± 4 years) with CMT using motion analysis and relate these findings back to the clinical assessment at the ankle. All patients underwent a motion analysis as a component of treatment decision-making.Lower extremity kinematics and kinetics were evaluated in comparison to a typically developing age-matched reference control group collected in the same gait laboratory. Three patient subgroups were defined based on peak ankle dorsiflexion in terminal stance: greater than typical (n = 23), within typical range (n = 30) and less than typical (n = 13). The three subgroups showed statistically significant differences (p < 0.004) in degree of impairment for ankle plantar flexor and dorsiflexor weakness and ankle plantar flexor contracture. Patients with excessive dorsiflexion in terminal stance had the greatest ankle plantar flexor weakness (median 2) and the greatest dorsiflexor weakness (median 4). Patients with less than typical dorsiflexion in terminal stance were the only patients with a plantar flexor contracture (?2 ± 9°). Delayed peak dorsiflexion in stance was the most common kinematic finding and consistent with ankle plantar flexor weakness. All patients showed significantly less (p < 0.001) peak ankle moments and power generation in terminal stance than the typically developing controls. We concluded that children and youth with CMT present differently in terms of impairment and associated gait issues which therefore require patient specific treatment strategies.     

Correlation between intravoxel incoherent motion MR parameters and MR nodular grade of parotid glands in patients with Sjögren’s syndrome: A pilot study

PurposeTo explore the correlation between intravoxel incoherent motion (IVIM) magnetic resonance (MR) parameters and MR nodular grade of parotid glands in patients with Sjögren’s syndrome (SS).Materials and methodsA total of 31 consecutive patients with SS and 28 gender- and age-matched healthy volunteers underwent bilateral parotid 3.0T MR examination including the IVIM sequence (9 b values, 0–800 s/mm²). The apparent diffusion coefficient (ADC), diffusion coefficient D, pseudo-diffusion coefficient D^*, and perfusion fraction f of bilateral parotid glands were obtained, and the nodular grade of each parotid gland was evaluated according to the MR morphological appearance.ResultsSixty-two parotid glands in 31 patients with SS consisted of 32, 14, 8, and 8 parotid glands at MR nodular grades 0, 1, 2, and 3, respectively. In parotid glands of grade 0, 1, 2, 3 and healthy volunteers, the ADC values were (1.13 ± 0.25, 1.11 ± 0.17, 1.05 ± 0.24, 0.89 ± 0.04 and 1.00 ± 0.21) × 10⁻³ mm²/s, D values were (0.92 ± 0.13, 0.90 ± 0.19, 0.90 ± 0.03, 0.67 ± 0.03, 0.81 ± 0.03) × 10⁻³ mm²/s, f values were 0.20 ± 0.04, 0.18 ± 0.02, 0.15 ± 0.01, 0.11 ± 0.01, 0.15 ± 0.06, and D^*values were (53.89 ± 28.26, 41.78 ± 16.35, 51.24 ± 18.69, 31.83 ± 18.03, 36.83 ± 16.14) × 10⁻³ mm²/s respectively. The ADC, D, f, and D^* values of parotid glands in patients with SS at grade 0 were significantly higher than those in healthy volunteers (all P < 0.05). Significant differences were observed in the D and f values of parotid glands in patients with SS among different grades (P = 0.003, < 0.001, respectively). The IVIM parameters (D, f) of parotid glands at early (grades 0–1) and advanced (grades 2–3) stages in patients with SS were significantly higher and lower, respectively, than those in healthy volunteers (all P < 0.05). The D and f values inversely correlated with MR nodular grades significantly (r = − 0.297, P = 0.019; r = − 0.653, P < 0.001, respectively)ConclusionThe parotid glands with different MR nodular grades in patients with SS showed different IVIM parameters, reflecting different pathophysiological characteristics of parotid glands at different stages.     

Plantarflexor passive-elastic properties related to BMI and walking performance in older women

The objective of this study was to examine the influence of BMI on the passive-elastic properties of the ankle plantarflexors in older women. Twenty-three women, 65–80 yr, were separated into normal weight (NW, BMI < 25.0 kg m⁻², n = 11) and overweight-obese (OW, BMI ≥ 25.0 kg m⁻², n = 12) groups. Resistive torque of the ankle plantarflexors was recorded on an isokinetic dynamometer by passively moving the ankle into dorsiflexion. Stiffness, work absorption, and hysteresis were calculated across an ankle dorsiflexion angle of 10–15°. Maximal plantarflexor strength was assessed, then participants walked at maximal speed on an instrumented gait analysis treadmill while muscle activation (EMG) was recorded. Plantarflexor stiffness was 34% lower in OW (26.4 ± 12.7 Nm rad⁻¹) than NW (40.0 ± 15.7 Nm rad⁻¹, p = 0.032). Neither work absorption nor hysteresis were different between OW and NW. Stiffness per kg was positively correlated to strength (r = 0.66, p < 0.001), peak vertical ground reaction force during walking (r = 0.72, p < 0.001), weight acceptance rate of force (r = 0.51, p = 0.007), push-off rate of force (r = 0.41, p = 0.026), maximal speed (r = 0.61, p = 0.001), and inversely correlated to BMI (r = −0.61, p = 0.001), and peak plantarflexor EMG (r = −0.40, p = 0.046). Older women who are OW have low plantarflexor stiffness, which may limit propulsive forces during walking and necessitate greater muscle activation for active force generation.     

Dorsiflexion deficit during jogging with chronic ankle instability

The purpose of the study was to determine whether individuals with chronic ankle instability (CAI) demonstrate altered dorsiflexion/plantar flexion range of motion (ROM) compared to controls during jogging. The case control study took place in a university motion analysis laboratory. Fourteen volunteers participated in the study, seven suffered from CAI (age 25 ± 4.2 years, height 173 ± 9.4 cm, mass 71 ± 8.1 kg) and seven were healthy, matched controls (age 25 ± 4.5 years, height 168 ± 5.9 cm, mass 67 ± 9.8 kg). All subjects jogged on an instrumented treadmill while a ten-camera motion analysis system collected three-dimensional kinematics of the lower extremities. The main outcome measure was sagittal plane (dorsiflexion/plantar flexion) range of motion of the ankle throughout the gait cycle. CAI subjects had significantly less dorsiflexion compared to the control group from 9% to 25% during jogging (4.83 ± 0.55°). CAI subjects demonstrated limited ankle dorsiflexion ROM during the time of maximal dorsiflexion during jogging. Limited dorsiflexion ROM during gait among individuals with CAI may be a risk factor for recurrent ankle sprains. These deficits should be treated appropriately by rehabilitation clinicians.     

The relationship between hip rotation range of movement and low back pain prevalence in amateur golfers: An observational study

ObjectiveTo investigate whether amateur golfers with self-reported low back pain have reduced hip rotation compared to asymptomatic controls.DesignObservational case-control study.SettingData collection took place at 2 amateur golf clubs in southern England.ParticipantsOn initial contact, all participants completed a screening questionnaire used to allocate participants into LBP (n = 28) and control groups (n = 36). LBP group were found to be heavier than controls (t = 2.242, 95% CI 0.763–13.332) but were matched for age, height, handedness, handicap, rounds played per week and years of play.Main outcome measuresPrimary outcome measures were lead and non-lead hip medial and lateral rotation in 0° of flexion as measured by inclinometer. Secondary measures included inter and intra-rater reliability.ResultsThe LBP group had significantly reduced lead hip passive (LBP 21.14 ± 10.17°; controls 31.06 ± 8.06°, t = ?4.228, 95% CI ?14.621–?5.205) and lead hip active medial rotation (LBP 21.46 ± 10.01; controls 28.06 ± 7.49°, t = ?2.908, 95% CI ?11.147–?2.036) compared to controls. No between group differences were found in non-lead hips or any passive or active lateral rotation measures.ConclusionAlthough there is lack of causality between LBP and hip rotation, the deficit in lead leg medial hip rotation in amateur golfers who suffer LBP may be relevant for screening or treatment selection.     

Tattoos do not affect exercise-induced localised sweat rate or sodium concentration

ObjectivesSkin tattoos have been shown to reduce localised sweat rate and increase sweat sodium concentration ([Na⁺]) when sweating is artificially stimulated. This study investigated whether similar responses are observed with exercise-induced sweating.DesignUnblinded, within-participant control, single trial.MethodsTwenty-two healthy individuals (25.1 ± 4.8 y (Mean ± SD), 14 males) with a unilateral tattoo ≥11.4 cm² in size, ≥2 months in age, and shaded ≥50% participated in this investigation. Participants undertook 20 min of intermittent cycling (4 × 5 min intervals) on a stationary ergometer in a controlled environment (24.6 ± 1.1 °C; 64 ± 6% RH). Resultant sweat was collected into absorbent patches applied at two pairs of contralateral skin sites (pair 1: Tattoo vs. Non-Tattoo; pair 2: Control 1 vs. Control 2 (both non-tattooed)), for determination of sweat rate and sweat [Na⁺]. Paired samples t-tests were used to determine differences between contralateral sites.ResultsTattoo vs. Non-Tattoo: Neither sweat rate (Mean ± SD: 0.92 ± 0.37 vs. 0.94 ± 0.43 mg·cm⁻²·min⁻¹, respectively; p = 0.693) nor sweat [Na⁺] (Median(IQR): 37(32–52) vs. 37(31–45) mM·L⁻¹, respectively; p = 0.827) differed. Control 1 vs. Control 2: Neither sweat rate (Mean±SD: 1.19 ± 0.53 vs. 1.19 ± 0.53 mg·cm⁻²·min⁻¹, respectively; p = 0.917) nor sweat [Na⁺] (Median(IQR): 29(26–41) vs. 31(25–43) mM·L⁻¹, respectively; p = 0.147) differed. The non-significant differences for sweat rate and [Na⁺] between Tattoo vs. Non-Tattoo were inside the range of the within participant variability (sweat rate CVi = 5.4%; sweat [Na⁺] CVi = 4.4%).ConclusionsSkin tattoos do not appear to alter the rate or [Na⁺] of exercise-induced sweating. The influence of skin tattoos on localised sweat responses may have previously been over-estimated.     

A new method for measuring AFO deformation,tibial and footwear movement in three dimensional gait analysis

Solid ankle-foot orthoses (AFOs) are designed to immobilise the ankle but numerous studies have measured a considerable ankle range of motion (ROM) in AFO users. Measurement of ankle kinematics may be affected by soft-tissue artefact (STA) of the knee marker, deformation of the AFO or tibial movement within the AFO. A new model based on the Conventional Gait Model (CGM) was developed to calculate these effects. Although movement of the AFO within the shoe should not affect the measured ankle joint angle the model also allows an estimation of this movement.Seven children (13 limbs) with spastic diplegic cerebral palsy were assessed to present the benefits of the new model compared to the CGM. STA of the knee marker was estimated to result in a 1.5° overestimation of total ankle ROM (from 8.2° to 9.7°). STA error was strongly related to angle of knee flexion (r = 0.82) with an average maximum error of 3.8°. AFO deformation contributed approximately two thirds of the ankle ROM (6.0 ± 4.3°) with the remaining third from tibial movement relative to the AFO (2.8 ± 0.9°). Movement of the AFO within the footwear was very small (1.8 ± 0.8°). A strong positive relationship (r = 0.9) was found between body mass (kg) and AFO deformation which was statistically significant (p < 0.001). This is the first model to attempt to quantify different contributions to ankle dorsiflexion measured during gait analysis of people wearing AFOs.     

Femoral torsion assessment with MRI in children: Should we use the bony or cartilaginous contours?

ObjectiveTo assess whether the use of cartilaginous contours at the femoral condyles instead of bony contours significantly changes femoral torsion measurements in children.Materials and MethodsFemoral torsion was measured in 32 girls (mean age 10.1 years ± 2.3 standard deviation) and 42 boys (10.9 years ± 2.5) on axial magnetic resonance (MR) images by two independent readers (R1,R2). The femoral condyle angle was measured using each the cartilaginous and bony contours of the distal femur. Cartilage thickness at femoral condyles was assessed. Intraclass-correlation-coefficient (ICC) and Pearson's correlation were used for statistical analysis.ResultsMean difference between cartilaginous and bony femoral torsion in girls was −1.1° ± 1.75 (range, −5.4° to 3.1°) for R1 and −1.64° ± 1.67 (−6.3° to 2.1°) for R2, in boys −1.5° ± 1.87 (−8.4° to 1.1°) for R1 and −2.28° ± 1.48 (−4.3° to 9.7°) for R2. Weak-to-moderate correlations between difference of cartilaginous-versus-bony measurements and cartilage thickness (r = −0.15 to −0.55, P < 0.001–0.46) or age (r = −0.33 to 0.46, P < 0.001–0.006) were found for both genders. Intermethod-ICC for cartilaginous versus bony femoral torsion measurements was 0.99/0.99 for R1/R2 in girls, and 0.99/0.98 in boys.ConclusionThere is only a small difference when measuring femoral torsion through cartilaginous versus bony contours, and no major difference in this between boys and girls.     

Post-match changes in neuromuscular function and the relationship to match demands in amateur rugby league matches

ObjectivesThe current study investigated the change in neuromuscular contractile properties following competitive rugby league matches and the relationship with physical match demands.DesignEleven trained, male rugby league players participated in 2–3 amateur, competitive matches (n = 30).MethodsPrior to, immediately (within 15-min) and 2 h post-match, players performed repeated counter-movement jumps (CMJ) followed by isometric tests on the right knee extensors for maximal voluntary contraction (MVC), voluntary activation (VA) and evoked twitch contractile properties of peak twitch force (Pt), rate of torque development (RTD), contraction duration (CD) and relaxation rate (RR). During each match, players wore 1 Hz Global Positioning Satellite devices to record distance and speeds of matches. Further, matches were filmed and underwent notational analysis for number of total body collisions.ResultsTotal, high-intensity, very-high intensity distances covered and mean speed were 5585 ± 1078 m, 661 ± 265, 216 ± 121 m and 75 ± 14 m min^?1, respectively. MVC was significantly reduced immediately and 2 h post-match by 8 ± 11 and 12 ± 13% from pre-match (p < 0.05). Moreover, twitch contractile properties indicated a suppression of Pt, RTD and RR immediately post-match (p < 0.05). However, VA was not significantly altered from pre-match (90 ± 9%), immediately-post (89 ± 9%) or 2 h post (89 ± 8%), (p > 0.05). Correlation analyses indicated that total playing time (r = ?0.50) and mean speed (r = ?0.40) were moderately associated to the change in post-match MVC, while mean speed (r = 0.35) was moderately associated to VA.ConclusionsThe present study highlights the physical demands of competitive amateur rugby league result in interruption of peripheral contractile function, and post-match voluntary torque suppression may be associated with match playing time and mean speeds.