Luca Laudani

Association between physical activity levels and physiological factors underlying mobility in young, middle-aged and older individuals living in a city district.

Maintaining adequate levels of physical activity is known to preserve health status and functional independence as individuals grow older. However, the relationship between determinants of physical activity (volume and intensity) and physiological factors underlying mobility (cardio-respiratory fitness, neuromuscular function and functional abilities) is still unclear. The aim of this study was to investigate the association between objectively quantified physical activity and a spectrum of physiological factors underlying mobility in young, middle-aged and older individuals living in a city district. Experiments were carried out on 24 young (28±2 years), 24 middle-aged (48±2 years) and 24 older (70±3 years) gender-matched volunteers. Physical activity was monitored by a wearable activity monitor to quantify volume and intensity of overall physical activity and selected habitual activities over 24 hours. Ventilatory threshold was assessed during an incremental cycling test. Torque, muscle fiber conduction velocity and agonist-antagonist coactivation were measured during maximal voluntary contraction of knee extensors and flexors. Ground reaction forces were measured during sit-to-stand and counter-movement jump. K-means cluster analysis was used to classify the participants’ physical activity levels based on parameters of volume and intensity. Two clusters of physical activity volume (i.e., high and low volume) and three clusters of physical activity intensity (i.e. high, medium and low intensity) were identified in all participants. Cardio-respiratory fitness was associated with volume of overall physical activity as well as lying, sitting, standing, walking and stair climbing. On the other hand, neuromuscular function and functional abilities showed a significant association with intensity of overall physical activity as well as postural transition, walking and stair climbing. As a practical application, the relative role played by volume and intensity of overall physical activity and selected habitual activities should be taken into account in the design of preventative training interventions to preserve mobility as individuals grow older.

An anterior ankle-foot orthosis improves walking economy in Charcot-Marie-Tooth type 1A patients.

Background: Ankle-foot orthoses are commonly prescribed in Charcot–Marie–Tooth type 1A disease to improve quality of walking and reduce the risk of falling due to the foot drop. Objectives: This study aimed at assessing the effect of an anterior ankle-foot orthosis on walking economy in a group of Charcot–Marie–Tooth type 1A patients. Study design: Within-group comparisons. Methods: 7 Charcot–Marie–Tooth type 1A patients (four women and three men; 37 ± 11 years; age range = 22–53 years) were asked to walk on a circuit at their self-selected speeds (‘slow’, ‘comfortable’ and ‘fast’) in two walking conditions: (1) with shoes only and (2) with Taloelast® anterior elastic ankle-foot orthoses. Speed of walking and metabolic cost of walking energy cost per unit of distance were assessed at the three self-selected speeds of walking for both walking conditions. Results: Speed of walking at the three self-selected speeds did not differ between shoes only and anterior elastic ankle-foot orthoses, whereas walking energy cost per unit of distance at comfortable speed was lower in patients using anterior elastic ankle-foot orthoses with respect to shoes only (2.39 ± 0.22 vs 2.70 ± 0.19 J kg−1 m−1; P < 0.05). Conclusions: In Charcot–Marie–Tooth type 1A patients, the use of anterior elastic ankle-foot orthoses improved walking economy by reducing the energy cost of walking per unit of distance, thus reflecting a lower level of metabolic effort and improved mechanical efficiency in comparison with shoes only. Clinical relevance From a practical perspective, Charcot–Marie–Tooth type 1A patients with anterior elastic ankle-foot orthoses can walk for a longer duration with a lower level of physical effort. Improvements in walking economy due to ankle-foot orthoses are likely a consequence of the reduction in steppage gait.

Application of the Sit-to-Stand Movement for the Early Assessment of Functional Deficits in Patients Who Underwent Anterior Cruciate Ligament Reconstruction

ObjectiveThe aims of this study were to identify and quantify functional deficits between the involved and the uninvolved limb as early as 1 mo after ACL reconstruction by means of a sit-to-stand movement on two force platforms. DesignGround reaction forces were measured in 73 patients who underwent ACL reconstruction, 47 with patellar tendon autograft and 26 with hamstring tendon autograft (ACL-H), and in 22 controls, who stood up from a seat as fast as possible. Side-to-side limb symmetry index (LSI) was calculated for peak force and rate of force development. ResultsThe LSI of vertical peak force was 59% in the patellar tendon autograft group and 68% in the ACL-H group, which were both lower than the 95% LSI of the controls (P < 0.001). The LSI of rate of force development was 27% in the patellar tendon autograft group and 48% in the ACL-H group, which were both lower than the 97% LSI of the controls (P < 0.001). After 2 mos, only in the ACL-H group, the LSI of both vertical peak force and rate of force development reached 88% and 80%, respectively, thus approaching the 96% and 92% LSI of the controls. ConclusionsSit-to-stand is effective for measuring functional deficits as early as 1 mo after ACL reconstruction. After 2 mos from surgery, the ACL-H group but not the patellar tendon autograft group approached the LSI of the control group, which may be attributed to differences in the graft.

Comparison in Joint-Position Sense and Muscle Coactivation Between Anterior Cruciate Ligament–Deficient and Healthy Individuals

CONTEXT Tearing of the anterior cruciate ligament (ACL) may disrupt the ability to recognize the knee position in space during limb-repositioning tasks, which is referred to as joint-position sense (JPS). Impairments in JPS have been shown to be lower during active than passive repositioning tasks, thus suggesting that coactivation patterns of the muscles surrounding the knee might compensate for the disrupted JPS and ensure accurate limb repositioning in ACL-deficient individuals. OBJECTIVE To investigate muscle coactivation patterns during JPS repositioning tasks in ACL-deficient and healthy individuals. DESIGN Prospective observational study. SETTING Functional assessment laboratory. PARTICIPANTS 8 men age 25 ± 8 y with isolated ACL rupture and 10 men age 30 ± 4 y with no history of knee injury. INTERVENTION JPS was evaluated by means of an electrogoniometer in a sitting position during either passive or active joint-positioning and -repositioning tasks with a 40° target knee angle. MAIN OUTCOME MEASURES Root mean square (RMS) of the surface electromyogram from the vastus lateralis and biceps femoris muscles was measured during active joint positioning and repositioning. RESULTS Healthy participants showed a significant decrease in vastus lateralis RMS (-19%) and an increase in biceps femoris RMS (+26%) during joint repositioning compared with positioning. In contrast, ACL-deficient patients showed no modulation in muscle coactivation between joint positioning and repositioning, although they exhibited significantly lower RMS of the vastus lateralis (injured limb, -28%; uninjured limb, -21%) and higher RMS of the biceps femoris (injured limb, +19%; uninjured limb, +30%) than the healthy participants during joint positioning. CONCLUSIONS The lack of modulation in muscle coactivation patterns between joint positioning and repositioning in ACL-deficient patients might be attributed to disrupted neural control after the injury-related loss of proprioceptive information. These results should be taken into account in the design of rehabilitation protocols with emphasis on muscle coactivation and JPS.

Asymmetrical Lower Extremity Loading Early After Anterior Cruciate Ligament Reconstruction Is a Significant Predictor of Asymmetrical Loading at the Time of Return to Sport.

Objectives The aim of this study was to examine whether asymmetrical lower limb loading early after anterior cruciate ligament reconstruction (1 mo) can predict asymmetrical lower limb loading at the time of return to sport (6 mos) and whether other early predictors as knee joint range of motion or maximal isometric strength affect this relationship. Design Ground reaction forces were measured during a sit-to-stand task 1 mo after anterior cruciate ligament reconstruction and a vertical countermovement jump 6 mos after anterior cruciate ligament reconstruction in 58 athletes. Other early postoperative measurements were knee joint range of motion (2 wks, 1 mo, and 2 mos after surgery) and maximal isometric strength of the knee extensor and flexor muscles (2 mos after surgery). Linear regression models were developed using side-to-side limb symmetry index (LSI) of countermovement jump as the dependent variable. Results LSI of sit-to-stand task 1 mo after surgery was a significant independent predictor of LSI of countermovement jump 6 mos after surgery. After accounting for deficits in knee joint range of motion and LSI of maximal isometric strength (&Dgr;R 2 = 0.35, P < 0.01), LSI of sit-to-stand task predicted LSI of countermovement jump (&Dgr;R 2 = 0.14 P < 0.01). Conclusions Asymmetrical lower extremity loading 1 mo after anterior cruciate ligament reconstruction is an early predictor of asymmetrical lower extremity loading 6 mos after surgery.

Effects of early whole-body vibration treatment on knee neuromuscular function and postural control after anterior cruciate ligament reconstruction: A randomized controlled trial

OBJECTIVE To assess the effects of adding a whole-body vibration protocol at optimal frequency (WBV-OF) to a traditional rehabilitation programme (TRP) early after anterior cruciate ligament reconstruction, on maximal strength and balance, in comparison with a traditional rehabilitation programme. DESIGN A total of 34 anterior cruciate ligament reconstructed patients with hamstring-tendon graft underwent either 4 weeks of WBV-OF training in addition to a traditional rehabilitation programme, or a traditional rehabilitation programme only, starting from the first month after surgery. Patients were assessed for maximal voluntary isometric strength during both knee extension and flexion and for balance on a force platform before, 1 month after treatment and at 3-month follow-up. RESULTS Strength symmetry of the knee flexor muscles improved in WBV-OF+TRP patients more than in TRP patients 1 month after treatment (mean 66% (standard deviation (SD) 15) vs 58% SD 13), and also at the 3-month follow-up (mean 77% (SD 15) vs 64% (SD 15)), with no differences in balance improvements between the groups. CONCLUSIONS Adding 4-weeks of WBV-OF to a traditional rehabilitation programme 1 month after surgery is effective in improving muscle strength of the knee flexor muscles. This early intervention may be incorporated into current rehabilitation to facilitate early strength recovery of anterior cruciate ligament reconstructed patients.

Older Age Is Associated with Lower Optimal Vibration Frequency in Lower-Limb Muscles During Whole-Body Vibration

ObjectiveThe aim of this study was to compare the optimal vibration frequency (OVF), which corresponds to maximal electromyographic muscle response during whole-body vibration, between young, middle-aged, and older women in four muscles of the lower-limbs. DesignOVF was measured as the frequency corresponding to maximal root mean square of the surface electromyogram (RMSmax) during a continuous incremental protocol, with a succession of vibration frequencies from 20 to 55 Hz (A = 2 mm), on the vastus lateralis, vastus medialis, rectus femoris, and gastrocnemius lateralis muscles of the dominant lower-limb. Seventy-eight women were divided into three age groups, that is, young, 21.6 ± 2.4 yrs; middle aged, 43.0 ± 5.2 yrs; and older, 74.2 ± 6.0 yrs. ResultsOVF in the vastus medialis was lower in the older women than in the middle-aged and young women, whereas OVF in the vastus lateralis was lower in the older than in the young women. There were no differences in OVF between muscles within each group. RMSmax was higher in the older than in the young women in all muscles. ConclusionsAge range should be taken into consideration when determining OVF because it decreases with age. Properly individualizing the vibration protocol might greatly influence neuromuscular effects of vibration training.

Effect of whole body vibration frequency on neuromuscular activity in ACL-deficient and healthy males

Whole-body vibration (WBV) has been shown to enhance muscle activity via reflex pathways, thus having the potential to contrast muscle weakness in individuals with rupture of the anterior cruciate ligament (ACL). The present study aimed to compare the magnitude of neuromuscular activation during WBV over a frequency spectrum from 20 to 45 Hz between ACL-deficient and healthy individuals. Fifteen males aged 28±4 with ACL rupture and 15 age-matched healthy males were recruited. Root mean square (RMS) of the surface electromyogram from the vastus lateralis in both limbs was computed during WBV in a static half-squat position at 20, 25, 30, 35, 40 and 45 Hz, and normalized to the RMS while maintaining the half-squat position without vibration. The RMS of the vastus lateralis in the ACL-deficient limb was significantly greater than in the contralateral limb at 25, 30, 35 and 40 Hz (P<0.05) and in both limbs of the healthy participants (dominant limb at 25, 30, 35, 40 and 45 Hz, P<0.05; non dominant limb at 20, 25, 30, 35, 40 and 45 Hz, P<0.05). The greater neuromuscular activity in the injured limb compared to the uninjured limb of the ACL-deficient patients and to both limbs of the healthy participants during WBV might be due to either augmented excitatory or reduced inhibitory neural inflow to motoneurons of the vastus lateralis through the reflex pathways activated by vibratory stimuli. The study provides optimal WBV frequencies which might be used as reference values for ACL-deficient patients.

Amount and intensity of daily living activities in Charcot-Marie-Tooth 1A patients.

Charcot–Marie–Tooth 1A (CMT1A) patients show a reduction of spontaneous activities of daily living measured by means of questionnaires or pedometers, which are quite inaccurate compared to recent measurement techniques.

Activation of Neck and Low-Back Muscles Is Reduced with the Use of a Neck Balance System Together with a Lumbar Support in Urban Drivers

Driving is associated with high activation of low-back and neck muscles due to the sitting position and perturbations imposed by the vehicle. The aim of this study was to investigate the use of a neck balance system together with a lumbar support on the activation of low-back and neck muscles during driving. Twelve healthy male subjects (age 32±6.71 years) were asked to drive in two conditions: 1) with devices; 2) without devices. During vehicle accelerations and decelerations root mean square (RMS) of surface electromyography (sEMG) was recorded from the erector spinae, semispinalis capitis and sternocleidomastoid muscles and expressed as a percentage of maximal voluntary contraction (MVC). The pitch of the head was obtained by means of an inertial sensor placed on the subjects’ head. A visual analog scale (VAS) was used to assess the level of perceived comfort. RMS of the low back muscles was lower with than without devices during both acceleration and deceleration of the vehicle (1.40±0.93% vs 29 2.32±1.90% and 1.88±1.45% vs 2.91±2.33%, respectively), while RMS of neck extensor muscles was reduced only during acceleration (5.18±1.96% vs 5.91±2.16%). There were no differences between the two conditions in RMS of neck flexor muscles, the pitch of the head and the VAS score. The use of these two ergonomic devices is therefore effective in reducing the activation of low-back and neck muscles during driving with no changes in the level of perceived comfort, which is likely due to rebalancing weight on the neck and giving a neutral position to lumbar segments.