Lower limb joint work and joint work contribution during downhill and uphill walking at different inclinations

Work performance and individual joint contribution to total work are important information for creating training protocols, but were not assessed so far for sloped walking. Therefore, the purpose of this study was to analyze lower limb joint work and joint contribution of the hip, knee and ankle to total lower limb work during sloped walking in a healthy population. Eighteen male participants (27.0 ± 4.7 yrs, 1.80 ± 0.05 m, 74.5 ± 8.2 kg) walked on an instrumented ramp at inclination angles of 0°, ±6°, ±12° and ±18° at 1.1 m/s. Kinematic and kinetic data were captured using a motion-capture system (Vicon) and two force plates (AMTI). Joint power curves, joint work (positive, negative, absolute) and each joint’s contribution to total lower limb work were analyzed throughout the stance phase using an ANOVA with repeated measures. With increasing inclination positive joint work increased for the ankle and hip joint and in total during uphill walking. Negative joint work increased for each joint and in total work during downhill walking. Absolute work was increased during both uphill (all joints) and downhill (ankle & knee) walking. Knee joint contribution to total negative and absolute work increased during downhill walking while hip and ankle contributions decreased. This study identified, that, when switching from level to a 6° and from 6° to a 12° inclination the gain of individual joint work is more pronounced compared to switching from 12° to an 18° inclination. The results might be used for training recommendations and specific training intervention with respect to sloped walking.     

Estimations of relative effort during sit-to-stand increase when accounting for variations in maximum voluntary torque with joint angle and angular velocity

The main purpose of this study was to compare three methods of determining relative effort during sit-to-stand (STS). Fourteen young (mean 19.6 ± SD 1.2 years old) and 17 older (61.7 ± 5.5 years old) adults completed six STS trials at three speeds: slow, normal, and fast. Sagittal plane joint torques at the hip, knee, and ankle were calculated through inverse dynamics. Isometric and isokinetic maximum voluntary contractions (MVC) for the hip, knee, and ankle were collected and used for model parameters to predict the participant-specific maximum voluntary joint torque. Three different measures of relative effort were determined by normalizing STS joint torques to three different estimates of maximum voluntary torque. Relative effort at the hip, knee, and ankle were higher when accounting for variations in maximum voluntary torque with joint angle and angular velocity (hip = 26.3 ± 13.5%, knee = 78.4 ± 32.2%, ankle = 27.9 ± 14.1%) compared to methods which do not account for these variations (hip = 23.5 ± 11.7%, knee = 51.7 ± 15.0%, ankle = 20.7 ± 10.4%). At higher velocities, the difference in calculating relative effort with respect to isometric MVC or incorporating joint angle and angular velocity became more evident. Estimates of relative effort that account for the variations in maximum voluntary torque with joint angle and angular velocity may provide higher levels of accuracy compared to methods based on measurements of maximal isometric torques.     

Changes in force and tendinous tissue elongation during the early phase of tetanic summation in in vivo human tibialis anterior muscle

The purpose of this study was to determine the changes that occur in tendinous tissue properties during the early phase of tetanic summation in the in vivo human tibialis anterior muscle (TA). The torque response and tendinous tissue elongation following single stimuli, two-pulse trains, and three-pulse trains were recorded in the TA during isometric contractions. The elongation, compliance, and lengthening velocity of tendinous tissue were determined by real-time ultrasonography. The contribution of the response to the second stimulation (C2) was obtained by subtracting the response to the single stimulation (C1) from the response of doublet. The third contribution (C3) was obtained by subtracting the response to the doublet from that of the triplet. C2 (7.8±0.5 Nm) and C3 (7.3±0.6 Nm) had torque responses significantly higher than C1 (3.6±0.7 Nm). In contrast, the elongations of tendinous tissue for C2 (2.8±0.4 mm) and C3 (1.7±0.2 mm) were significantly lower than for C1 (4.9±0.3 mm), indicating that the summation pattern of tendinous tissue elongation is different from the summation pattern of torque response. In addition, this showed considerable difference both between C1 (0.12±0.01 mm/N; 83±4.6 mm/s) and C2 (0.03±0.005 mm/N; 50±6.3 mm/s) and between C1 and C3 (0.02±0.002 mm/N; 39±6.4 mm/s) in the compliance and lengthening velocity of tendinous tissue. These results suggest that changes in tendinous tissue properties between first and second contraction are related to different summation patterns of force and tendinous tissue elongation during early phase of tetanic summation.     

Estimating severity of sideways fall using a generic multi linear regression model based on kinematic input variables

Many research groups have studied fall impact mechanics to understand how fall severity can be reduced to prevent hip fractures. Yet, direct impact force measurements with force plates are restricted to a very limited repertoire of experimental falls. The purpose of this study was to develop a generic model for estimating hip impact forces (i.e. fall severity) in in vivo sideways falls without the use of force plates.Twelve experienced judokas performed sideways Martial Arts (MA) and Block (‘natural’) falls on a force plate, both with and without a mat on top. Data were analyzed to determine the hip impact force and to derive 11 selected (subject-specific and kinematic) variables. Falls from kneeling height were used to perform a stepwise regression procedure to assess the effects of these input variables and build the model.The final model includes four input variables, involving one subject-specific measure and three kinematic variables: maximum upper body deceleration, body mass, shoulder angle at the instant of ‘maximum impact’ and maximum hip deceleration. The results showed that estimated and measured hip impact forces were linearly related (explained variances ranging from 46 to 63%). Hip impact forces of MA falls onto the mat from a standing position (3650 ± 916 N) estimated by the final model were comparable with measured values (3698 ± 689 N), even though these data were not used for training the model. In conclusion, a generic linear regression model was developed that enables the assessment of fall severity through kinematic measures of sideways falls, without using force plates.     

Muscular activation patterns during active prone hip extension exercises

BackgroundChanges in activation patterns of hip extensors and pelvic stabilizing muscles are recognized as factors that cause low back disorders and these disturbances could have an impact on the physiological loading and alter the direction and magnitude of joint reaction forces.ObjectiveTo investigate activation patterns of the gluteus maximus, semitendinosus and erector spinae muscles with healthy young individuals during four different modalities of therapeutic exercise.MethodsThirty-one volunteers were selected: (16 men and 15 women), age (24.5 ± 3.47 years), body mass of 66.89 ± 11.89 kg and a height of 1.70 ± 0.09 m). They performed four modalities of therapeutic exercise while the electromyographic activity of the investigated muscles was recorded to determine muscle pattern activation for each exercise.ResultsRepeated measure ANOVA revealed that muscle activation patterns were similar for the four analyzed exercises, starting with the semitendinosus, followed by the erector spinae, and then, the gluteus maximus. The gluteus maximus was the last activated muscle during hip extension associated with knee flexion (p < 0.0001), knee extension (p < 0.0001), and with lateral rotation and knee flexion (p < 0.05).ConclusionFindings of the present study suggested that despite individual variability, the muscle firing order was similar for the four therapeutic exercises.     

Joint-specific power production and fatigue during maximal cycling

Cycling power decreases substantially during a maximal cycling trial of just 30 s. It is not known whether movement patterns and joint powers produced at each joint decrease to a similar extent or if each joint exhibits an individual fatigue profile. Changes in movement patterns and/or joint powers associated with overall task fatigue could arise from several different mechanisms or from a complex interplay of these mechanisms. The purpose of this investigation was to determine the changes in movement and power at each joint during a fatiguing cycling trial. Thirteen trained cyclists performed a 30 s maximal cycling trial on an isokinetic cycle ergometer at 120 rpm. Pedal forces and limb kinematics were recorded. Joint powers were calculated using a sagittal plane inverse dynamics model and averaged for the initial, middle, and final three second intervals of the trial, and normalized to initial values. Relative ankle plantar flexion power was significantly less than all other joint actions at the middle interval (51±5% of initial power; p=0.013). Relative ankle plantar flexion power for the final interval (37±3%) was significantly less than the relative knee flexion and hip extension power (p=0.010). Relative knee extension power (41±5%) was significantly less than relative hip extension power (55±4%) during the final three second interval (p=0.045). Knee flexion power (47±5%) did not differ from relative hip extension power (p=0.06). These changes in power were accompanied by a decrease in time spent extending by each joint with fatigue (i.e., decreased duty cycle, p<0.03). While central mechanisms may have played a role across all joints, because the ankle fatigued more than the hip and knee joints, either peripheral muscle fatigue or changes in motor control strategies were identified as the potential mechanisms for joint-specific fatigue during a maximal 30 s cycling trial.     

Effect of a change in step direction from a forward to a lateral target in response to a sensory perturbation

The aim of the current study was to investigate the response of healthy older and young adults to a change in step direction from a forward to a lateral target in response to a sensory perturbation. Nine healthy older (75.1 ± 6.7 years; age range, 65–81 years) and nine young adults (27 ± 3.6 years; age range, 23–31 years) participated in the study. The sensory perturbation was a visual cue presented at random times while subjects stepped over an obstacle from quiet stance. For both young and elderly subjects there was an abrupt change in the slope of both shear ground reaction forces (GRFs) of the stance limb following the perturbation. The slope and peak of the change in GRFs was greater for the young subjects and the onset significantly earlier (205 ms compared to 271 ms). Changes in the GRFs were accompanied by an increase in bilateral gluteus medius and stance limb soleus activity. A late visual cue resulted in a delayed response for elderly subjects. These data show that a stepping response to a sensory perturbation was both delayed and of less magnitude for older adults which has implications for fall risk.     

The surface electromyographic evaluation of the Functional Reach in elderly subjects

This study proposes a comprehensive assessment of myoelectric activity of the main muscles involved in the Functional Reach (FR) test, in 24 elderly subjects. A specific protocol for the surface electromyography (sEMG) signal acquisition during FR-test was developed. Results show that anterior muscles activate following a caudo-cranial order. Tibialis Anterior (TA) is the first to be activated (−18.0 ± 16.3% of the FR-period), together with Rectus Femoris (−10.4 ± 17.9%). Then, Rectus Abdominis (19.7 ± 24.7%) and Sternocleidomastoideus (19.9 ± 15.6%) activate after the FR-start. Hamstrings, Soleus, and L4-level Erectores Spinae (posterior muscles) activate after the FR-start in this order (11.4 ± 16.8%, 17.7 ± 16.6%, and 35.2 ± 29.0%, respectively) and remain active until the movement end. The analysis of the kinematic strategies adopted by subjects revealed an association between TA-activation patterns and two kinematic strategies (hip/mixed strategy), quantified by an increase (p < 0.05) of TA-activity duration in subjects adopting the hip strategy (89.9 ± 34.5) vs. subjects adopting the mixed strategy (27.0 ± 16.8). This suggests that TA sEMG activity could be able to discriminate among kinematic strategies, providing different information on balance control. Thus, the present analysis represents the first attempt to quantify the sEMG activity during FR-test in elderly subjects, providing an early contribution in building a reference frame for balance assessment in clinical context.     

Higher medially-directed joint reaction forces are a characteristic of dysplastic hips: A comparative study using subject-specific musculoskeletal models

Acetabular dysplasia is a known cause of hip osteoarthritis. In addition to abnormal anatomy, changes in kinematics, joint reaction forces (JRFs), and muscle forces could cause tissue damage to the cartilage and labrum, and may contribute to pain and fatigue. The objective of this study was to compare lower extremity joint angles, moments, hip JRFs and muscle forces during gait between patients with symptomatic acetabular dysplasia and healthy controls. Marker trajectories and ground reaction forces were measured in 10 dysplasia patients and 10 typically developing control subjects. A musculoskeletal model was scaled in OpenSim to each subject and subject-specific hip joint centers were determined using reconstructions from CT images. Joint kinematics and moments were calculated using inverse kinematics and inverse dynamics, respectively. Muscle forces and hip JRFs were estimated with static optimization. Inter-group differences were tested for statistical significance (p ≤ 0.05) and large effect sizes (d ≥ 0.8). Results demonstrated that dysplasia patients had higher medially directed JRFs. Joint angles and moments were mostly similar between the groups, but large inter-group effect sizes suggested some restriction in range of motion by patients at the hip and ankle. Higher medially-directed JRFs and inter-group differences in hip muscle forces likely stem from lateralization of the hip joint center in dysplastic patients. Joint force differences, combined with reductions in range of motion at the hip and ankle may also indicate compensatory strategies by patients with dysplasia to maintain joint stability.     

The relationship between external knee moments and muscle co-activation in subjects with medial knee osteoarthritis

PurposeExternal knee moments are reliable to measure knee load but it does not take into account muscle activity. Considering that muscle co-activation increases compressive forces at the knee joint, identifying relationships between muscle co-activations and knee joint load would complement the investigation of the knee loading in subjects with knee osteoarthritis. The purpose of this study was to identify relationships between muscle co-activation and external knee moments during walking in subjects with medial knee osteoarthritis.Methods19 controls (11 males, aged 56.6 ± 5, and BMI 25.2 ± 3.3) and 25 subjects with medial knee osteoarthritis (12 males, aged 57.3 ± 5.3, and BMI 28.2 ± 4) were included in this study. Knee adduction and flexion moments, and co-activation (ratios and sums of quadriceps, hamstring, and gastrocnemius) were assessed during walking and compared between groups. The relationship between knee moments and co-activation was investigated in both groups.FindingsSubjects with knee osteoarthritis presented a moderate and strong correlation between co-activation (ratios and sums) and knee moments.InterpretationMuscle co-activation should be used to measure the contribution of quadriceps, hamstring, and gastrocnemius on knee loading. This information would cooperate to develop a more comprehensive approach of knee loading in this population.     

Axial BMD in Diabetic and Nondiabetic Southeast Asians with HIP Fractures: Do Race and Body Mass Index Matter?

Objective: Obesity is less prevalent in Asian subjects with type 2 diabetes mellitus (T2DM) in contrast to Caucasians. Whether higher axial bone mineral density (BMD) often reported in T2DM is independent of body mass index (BMI) has not been clearly shown. BMD characterization in T2DM patients with hip fractures has also not been performed. We compared the BMD of Asian diabetic and nondiabetic patients with new hip fractures and explored how BMD was influenced by BMI.Methods: We included 255 diabetic and 148 nondiabetic patients. BMD adjusted for age; BMI; race; sex; renal function; and use of statins, proton pump inhibitors, steroids, anticonvulsants, and calcium and/or vitamin D supplements were compared between the groups. We were particularly interested in the BMD comparison between underweight diabetics and nondiabetics with hip fractures.Results: The presence of T2DM was associated with higher BMD (g/cm²) at the femoral neck (0.527 ± 0.103 vs. 0.491 ± 0.102, P<.01) and lumbar spine [LS] (0.798 ± 0.147 vs. 0.723 ± 0.156, P<.01). This association persisted after adjustment for multiple confounding variables including BMI. The age-, BMI-, and sex-adjusted LS BMD was higher in underweight (BMI <18.5 kg/m²) diabetics compared to similar weight nondiabetics (0.733 ± 0.126 vs. 0.649 ± 0.131 g/cm², P = .014).Conclusion: T2DM is independently associated with higher axial BMD in patients with new hip fractures. The finding of higher BMD even in underweight diabetics with hip fractures compared to their nondiabetic counterparts suggests that higher BMD in subjects with T2DM is not due to higher BMI.Abbreviations:BMD = bone mineral densityBMI = body mass indexCV = coefficient of variationDXA = dual-energy X-ray absorptiometryHbA1c = glycated hemoglobinIGF-1 = insulin growth factor-1LS = lumbar spine25(OH)D = 25-hydroxyvitamin DT2DM = type 2 diabetes mellitus     

Effects of the pelvic compression belt on gluteus medius,quadratus lumborum,and lumbar multifidus activities during side-lying hip abduction

The aims of this study were to assess the effect of the pelvic compression belt on the electromyographic (EMG) activities of gluteus medius (GM), quadratus lumborum (QL), and lumbar multifidus (LM) during side-lying hip abduction. Thirty-one volunteers (15 men and 16 women) with no history of pathology volunteered for this study. Subjects were instructed to perform hip abduction in side-lying position with and without applying the pelvic compression belt. The pelvic compression belt was adjusted just below the anterior superior iliac spines with the stabilizing pressure using elastic compression bands. Surface EMG data were collected from the GM, QL, and LM of the dominant limb. Significantly decreased EMG activity in the QL (without the pelvic compression belt, 60.19 ± 23.66% maximal voluntary isometric contraction [MVIC]; with the pelvic compression belt, 51.44 ± 23.00% MVIC) and significantly increased EMG activity in the GM (without the pelvic compression belt, 26.71 ± 12.88% MVIC; with the pelvic compression belt, 35.02 ± 18.28% MVIC) and in the LM (without the pelvic compression belt, 30.28 ± 14.60% MVIC; with the pelvic compression belt, 37.47 ± 18.94% MVIC) were found when the pelvic compression belt was applied (p < 0.05). However, there were no significant differences of the EMG activity between male and female subjects. The findings suggest that the pelvic compression belt may be helpful to prevent unwanted substitution movement during side-lying hip abduction, through increasing the GM and LM and decreasing the QL.     

Differences in neuromuscular control between impact and no impact roundhouse kick in athletes of different skill levels

This study aimed at investigating two aspects of neuromuscular control around the hip and knee joint while executing the roundhouse kick (RK) using two techniques: Impact RK (IRK) at trunk level and No-Impact RK at face level (NIRK). The influence of technical skill level was also investigated by comparing two groups: elite Karateka and Amateurs. Surface electromyographic (sEMG) signals have been recorded from the Vastus Lateralis (VL), Biceps Femoris (BF), Rectus Femoris (RF), Gluteus Maximum (GM) and Gastrocnemious (GA) muscles of the kicking leg in six Karateka and six Amateurs performing the RKs. Hip and knee kinematics were also assessed. EMG data were rectified, filtered and normalized to the maximal value obtained for each muscle over all trials; co-activation (CI) indexes of antagonist vs. overall (agonist and antagonist) activity were computed for hip and knee flexion and extension. Muscle Fiber Conduction Velocity (CV) obtained from VL and BF muscles was assessed as well. The effect of group and kick on angular velocity, CIs, and CVs was tested through a two-way ANOVA (p < 0.05). An effect of group was showed in both kicks. Karateka presented higher knee and hip angular velocity; higher BF-CV (IRK: 5.1 ± 1.0 vs. 3.5 ± 0.5 m/s; NIRK: 5.7 ± 1.3 vs. 4.1 ± 0.5 m/s), higher CIs for hip movements and knee flexion and lower CI for knee extension. The results obtained suggest the presence of a skill-dependent activation strategy in the execution of the two kicks. CV results are suggestive of an improved ability of elite Karateka to recruit fast MUs as a part of training induced neuromuscular adaptation.     

The effects of cycling cadence on the phases of joint power,crank power,force and force effectiveness

We examined the influence of cadence in cycling technique by quantifying phase relationships for a number of important variables at the crank and lower extremity joints. Any difference in the effect of cadence on force, effectiveness, and power phases would indicate an essential change in coordination pattern. Cycle kinetics was recorded for 10 male competitive cyclists at five cadences (60–100 rpm) at submaximal load (260 W). Joint powers were calculated using inverse dynamics methods. All data were expressed as a function of crank position. The phase of the crank mechanical profiles (total force, crank and joint power, and effectiveness) was calculated using four methods: crank angle of maximum (MA) and minimum (MI), fitting a sine wave (SI) and by cross-correlation (XC). These methods, apart from the MA method, showed the same relative phase. The variables, however, showed different phases being expressed as time lag: force effectiveness: 0.131 (±0.034) s; total force: 0.149 (±0.021) s; power: 0.098 (±0.027) s. The phases in joint powers hip 0.071 (±0.008), knee 0.082 (±0.009), and hip 0.077 (±0.012) were only well described by XC, and were somewhat lower than the crank power phase. These differences indicate the potential effect of inertia of the lower limb in phase shifts from joints to crank. Furthermore, the differences between the various crank variables indicate a change of technique with cadence.     

Multi-channel electromyography during maximal isometric and dynamic contractions

Motor unit behavior differs between contraction types at submaximal contraction levels, however is challenging to study during maximal voluntary contractions (MVCs). With multi-channel surface electromyography (sEMG), mean physiological characteristics of the active motor units can be extracted. Two 8-electrode sEMG arrays were attached on biceps brachii muscle (one on each head) to examine behavior of sEMG variables during isometric, eccentric and concentric MVCs of elbow flexors in 36 volunteers.On average, isometric (364 ± 88 N) and eccentric (353 ± 74 N) MVCs were higher than concentric (290 ± 73 N) MVC (p < 0.001). Mean muscle fiber conduction velocity (CV) was highest during eccentric MVC (4.42 ± 0.49 m/s) than concentric (4.25 ± 0.49 m/s, p < 0.01) and isometric (4.14 ± 0.45 m/s, p < 0.001) MVCs. Furthermore, eccentric MVC showed lower sEMG amplitude at the largest elbow joint angles (120–170°) and higher CV at the smallest (70–150°) elbow joint angles (p < 0.05–0.001) than concentric MVC.The differences in CV and sEMG amplitude between the MVCs suggest that the control strategy of motor units differs between the contraction types during MVCs, and is dependent on the muscle length between the dynamic MVCs.     

Performance of Toggenburg dairy goats in smallholder production systems of the eastern highlands of Kenya

The use of exotic dairy goats in breeding programmes for smallholder production systems is popular in Eastern Africa. However, information on the performance of exotic breeds within these systems is scarce. This paper presents information on performance of Toggenburg dairy goats under smallholder production systems in a medium to high agricultural potential environment in Kenya under a community-based set-up as part of the characterization of its adaptive and productive attributes. Environmental factors affecting growth of 646 goats born in the environment, and fertility and milk production of 160 does from 1997 to 2005 were evaluated. Genetic parameters were also estimated for early growth traits. The average birth weight (BW) for 607 kids was 3.27 kg. Corrected weaning weights (CW), and average daily gain to weaning (ADG) for 646 kids were 19.12 kg and 136 g/day, respectively. The results indicated that the smallholder farmers were able to maintain comparably high levels of milk production in the first three parities (LMY), with yields of 475 ± 9 l in 201 days for 160 does in the first parity, 507 ± 9 l in 264 days from 130 does in the second parity and 513 ± 13 l in 296 days for 82 does in the third parity. Kidding intervals though initially long decreased with time to reasonable levels (302 ± 117 days). The heritability estimates obtained were low (0.23 ± 0.13 for BW, 0.18 ± 0.11 for CW and 0.14 ± 0.11 for ADG). Genetic correlations between the traits were also low. Genetic and phenotypic trends indicated little change in BW, CW and LMY over the years. The phenotypic trend in the kidding interval showed a reducing interval over time. The results demonstrated that the Toggenburg goats were able to perform and thrive reasonably well under the low-input farming conditions.     

Corrective sitting strategies: An examination of muscle activity and spine loading

The purpose of this study was to quantify the load on the lumbar spine of subjects when they are asked to adjust from a slouched sitting posture into an upright posture with one of three different strategies: “free” (no instruction) and two coached patterns: “lumbopelvic” dominant and “thoracic” dominant. The activity of selected muscles and kinematic data was recorded from 20 volunteers while performing the three movement patterns to adjust sitting posture. Moments and forces at the lumbar spine were computed from an anatomically detailed model that uses kinematics and muscle activation as input variables.The lumbopelvic pattern produces less joint moment on the lumbar spine (on average 31.2 ± 3.9 N m) when compared to the thoracic pattern (43.8 ± 5.8 N m). However, the joint compression force was similar for these two patterns, but it was smaller in the free pattern, when no coaching was given (lumbopelvic: 1279 ± 112 N, thoracic: 1367 ± (125 N, free: 1181 ± 118 N). Lower thoracic erector muscle activity and higher lumbar erector activity were measured in the lumbopelvic pattern in comparison with the other two. In summary the lumbopelvic pattern strategy using predominantly the movement of anterior pelvic tilt results in smaller joint moments on the lumbar spine and also positions the lumbar spine closest to the neutral posture minimizing passive tissue stress. This may be the strategy of choice for people with low back flexion intolerance.     

Evaluación de la utilización de las prestaciones específicas de los sistemas de infusión subcutánea de insulina y su relación con el control metabólico en pacientes con diabetes tipo 1

Background and objectivePatients with type 1 diabetes (T1DM) treated with continuous subcutaneous insulin infusion (CSII) have available several specific features of these devices. The aim of this study was to evaluate the relationship between real use of them and the degree of glycemic control in patients using this therapy.Patients and methodsForty-four T1DM patients on CSII therapy with or without real-time continuous glucose monitoring (CGM) were included. Data from 14 consecutive days were retrospectively collected using the therapy management software CareLink Personal/Pro^® and HbA1c measurement performed at that period. The relationship between the frequency of usie of specific features of insulin pumps (non-sensor augmented or sensor-augmented) and glycemic control was analyzed.ResultsMean HbA1c in the group was 7.5 ± .8%. Mean daily number of boluses administered was 5.1 ± 1.8, with 75.4% of them being bolus wizards (BW). Daily number of boluses was significantly greater in patients with HbA1c < 7.5% than in those with HbA1c > 7.5% (5.3 ± 1.6 vs. 4.3 ± 1.6, P = .056). There was a trend to greater use of BW in patients with better control (82.8 ± 21.4% vs. 69.9 ± 29.1%, P = .106). HbA1c was lower in patients using CGM (n = 8) as compared to those not using sensor-augmented pumps (7.6 ± .8 vs 7.1 ± .7, P = .067), but the difference was not statistically significant.ConclusionsMore frequent use of BW appears to be associated to better metabolic control in patients with T1DM using pump therapy. In standard clinical practice, augmentation of insulin pump with CGM may be associated to improved glycemic control.     

In vivo moment generation and architecture of the human plantar flexors after different shortening–stretch cycles velocities

The purpose of this study was to examine the moment generation of the human plantar flexors and the architecture of the gastrocnemius medialis muscle during and after shortening–stretch cycles in vivo. Fourteen male subjects (30 ± 7 years, 177 ± 7 cm, 80 ± 9 kg) performed a series of electro-stimulated shortening–stretch plantar flexion contractions. The shortening–stretch cycles were performed at three constant angular velocities (25°/s, 50°/s, 100°/s), two amplitudes (15° and 25° ankle angle changes) and at two different stimulation frequencies (30 Hz and 85 Hz). The resultant ankle joint moments were calculated through inverse dynamics. Pennation angle and fascicle length of the m. gastrocnemius medialis at rest and during contractions were measured using ultrasonography. The corresponding ankle moments, kinematics and changes in muscle architecture were analysed at seven time intervals. A three-way analysis of variance (amplitude × velocity × stimulation frequency) and post-hoc test with Bonferroni correction were used to check the amplitude, velocity and stimulation level related effects on moment enhancement (α = 0.05). The results show an ankle joint moment enhancement after shortening–stretch cycles influenced by muscle architectural changes. We found 2–3% isometric ankle joint moment enhancement at steady state, 1.5–2.0 s after the shortening–stretch cycle. However, the observed alteration in muscle architecture after the imposed perturbation, could lead to an underestimation (1–3%) of joint moment enhancement due to the force–length relationship of the triceps surae. Furthermore, the enhancement observed was independent of the shortening–stretch amplitude, velocity and stimulation frequency.