Evaluation of physical fitness in 11 years old students in Northern Italy: a powerful tool to improve physical education curricula

Purpose: This study was designed to evaluate the physical fitness (PF) in 11 years old students of 7 schools in Brescia. The aim was to provide functional data useful for motor activity promotion by physical education (PE) teaching in middle-lower school. Methods: To assess the four main components of the PF we measured: (1) anthropometric data, i.e. height (m), weight (kg) to calculate BMI (kg/m2); (2) aerobic fitness through the six minutes walking test (6MWT); (3) muscular fitness through the standing broad jump test (SBJT); (4) joint flexibility from the V-Sit and reach test (VSR). Statistical analysis was performed by 2-way ANOVA. Results: 349 children were tested, 257 Italian (I) and 74 Not-Italian (NI); I: 127 males (M) and 130 females (F); NI: 41 M and 33 F. NI children belonged to different ethnic groups. BMI I-M (19.3 +- 3.3) I-F (19.5 +- 3.7) NI-M (20.7 +- 3.6) NI-F (19.9 +- 4.5) 6MWT I-M (720 +- 59) I-F (697 +- 54) NI-M (704 +- 75) NI-F (683 +- 52) SBJT I-M (154 +- 22) I-F (144 +- 21) NI-M (145 +- 24) NI-F (137 +- 21) VSR I-M (- 7 +- 7) I-F (4 +-10) NI-M (- 5 +- 8) NI-F (- 1 +- 10) Statistical differences between groups. BMI I vs NI; M-I vs M-NI; SBJT I vs NI; M(I + NI) vs F(I + NI); M-I vs F-I; VSR M(I + NI) vs F(I + NI); M(I) vs F(I) Conclusions: I group data. BMI mean value of both M and F is close to the 50th percentile according to a previous study concerning North of Italy children. Nonetheless, 15% of M and 11% of F have to be considered overweight [1]. 6MWT and SBJT mean results are even better than those reported for other age-matched European children [2, 3]. VSR data are strongly influenced by gender. M show marked negative results, while F show good flexibility. This difference should be considered in PE curriculum. NI group data. Only two of the PF descriptors are different compared to I data, being BMI and SBJT value higher and lower, respectively, than those of I counterpart. Generally, the resulting overall PF of the investigated students is in line with the literature data. The level of PF can be considered adequate, making this population able to follow PE curriculum aimed to include physical activity in daily life as a tool to discourage its abandon in adulthood. References Cacciari E et al (2002) Eur J Clin Nutr 56:171–180 Ulrich S et al (2013) BMC Pulm Med 13:49–60 Ortega FB et al (2011) Br J Sports Med 45:20–2

Motor unit conduction velocity at different joint angles

Purpose: The aim of this study was to evaluate the dependence of motor unit conduction velocity (MUCV) on the length of the muscle. Methods: Muscle length was modified considering three different ankle angles: 90°,110° and 130°. For each angle the maximal voluntary contraction (MVC) was measured during static ankle dorsiflexion. High-density surface electromyography (HD-sEMG, 128 channels) was recorded from the tibialis anterior muscle (TA) in six young individuals. Subjects executed a volitional effort in which the output tension changed in a trapezoidal ramp fashion (15 s transient and 40 s steady contraction). Two levels of steady contraction were investigated: 10% and 20% of MVC. Using a novel decomposition technique based on HD-sEMG processing (Negro et al. 2016), the individual MUCV values were estimated during the trapezoid steady part. The decomposition was performed at each ankle angle independently, and the MU action potentials were not tracked across different muscle lengths. Results: MVC mean values at 90° and 130° were 91.78% and 78.77% of 110° value respectively. Considering that there was no statistical difference between the MUCV estimations calculated at 10 and 20% MVC, the values were grouped. The average CV was 4.00 ± 0.54 m/ s for 90°, 3.88 ± 0.19 m/s for 110° and 3.77 ± 0.37 m/s for 130°. One-Way Anova analysis showed a weak effect between the three conditions (P = 0.04). Conclusion: MUCV changes were weakly related to the different muscle lengths. Explanation of our results should consider that the muscle fiber can be approximated as a constant volume system and that, from the cable theory, the smaller the diameter the lower the CV is. On these bases, the reduction of muscle fibers transverse diameter during muscle elongation when the ankle angle increases from 90° to 130° could be a possible explanation for our results

Hand Passive Mobilization Performed with Robotic Assistance: Acute Effects on Upper Limb Perfusion and Spasticity in Stroke Survivors

This single arm pre-post study aimed at evaluating the acute effects induced by a single session of robot-assisted passive hand mobilization on local perfusion and upper limb (UL) function in poststroke hemiparetic participants. Twenty-three patients with subacute or chronic stroke received 20 min passive mobilization of the paretic hand with robotic assistance. Near-infrared spectroscopy (NIRS) was used to detect changes in forearm tissue perfusion. Muscle tone of the paretic UL was assessed by the Modified Ashworth Scale (MAS). Symptoms concerning UL heaviness, joint stiffness, and pain were evaluated as secondary outcomes by self-reporting. Significant (p=0.014) improvements were found in forearm perfusion when all fingers were mobilized simultaneously. After the intervention, MAS scores decreased globally, being the changes statistically significant for the wrist (from 1.6±1.0 to 1.1±1.0; p=0.001) and fingers (from 1.2±1.1 to 0.7±0.9; p=0.004). Subjects reported decreased UL heaviness and stiffness after treatment, especially for the hand, as well as diminished pain when present. This study supports novel evidence that hand robotic assistance promotes local UL circulation changes, may help in the management of spasticity, and acutely alleviates reported symptoms of heaviness, stiffness, and pain in subjects with poststroke hemiparesis. This opens new scenarios for the implications in everyday clinical practice. Clinical Trial Registration Number is NCT03243123

Muscle contractile properties directly influence shared synaptic inputs to spinal motor neurons

Alpha band oscillations in shared synaptic inputs to the alpha motor neuron pool can be considered an involuntary source of noise that hinders precise voluntary force production. This study investigated the impact of changing muscle length on the shared synaptic oscillations to spinal motor neurons, particularly in the physiological tremor band. Fourteen healthy individuals performed low-level dorsiflexion contractions at ankle joint angles of 90° and 130°, while high-density surface electromyography (HDsEMG) was recorded from the tibialis anterior (TA). We decomposed the HDsEMG into motor units spike trains and calculated the motor units’ coherence within the delta (1–5 Hz), alpha (5–15 Hz), and beta (15–35 Hz) bands. Additionally, force steadiness and force spectral power within the tremor band were quantified. Results showed no significant differences in force steadiness between 90° and 130°. In contrast, alpha band oscillations in both synaptic inputs and force output decreased as the length of the TA was moved from shorter (90°) to longer (130°), with no changes in delta and beta bands. In a second set of experiments (10 participants), evoked twitches were recorded with the ankle joint at 90° and 130°, revealing longer twitch durations in the longer TA muscle length condition compared to the shorter. These experimental results, supported by a simple computational simulation, suggest that increasing muscle length enhances the muscle's low-pass filtering properties, influencing the oscillations generated by the Ia afferent feedback loop. Therefore, this study provides valuable insights into the interplay between muscle biomechanics and neural oscillations

Neural Filtering of Physiological Tremor Oscillations to Spinal Motor Neurons Mediates Short-Term Acquisition of a Skill Learning Task

The acquisition of a motor skill involves adaptations of spinal and supraspinal pathways to alpha motoneurons. In this study, we estimated the shared synaptic contributions of these pathways to understand the neural mechanisms underlying the short-term acquisition of a new force-matching task. High-density surface electromyography (HDsEMG) was acquired from the first dorsal interosseous (FDI; 7 males and 6 females) and tibialis anterior (TA; 7 males and 4 females) during 15 trials of an isometric force-matching task. For two selected trials (pre- and post-skill acquisition), we decomposed the HDsEMG into motor unit spike trains, tracked motor units between trials, and calculated the mean discharge rate and the coefficient of variation of interspike interval (COVISI). We also quantified the post/pre ratio of motor units’ coherence within delta, alpha, and beta bands. Force-matching improvements were accompanied by increased mean discharge rate and decreased COVISI for both muscles. Moreover, the area under the curve within alpha band decreased by ∼22% (TA) and ∼13% (FDI), with no delta or beta bands changes. These reductions correlated significantly with increased coupling between force/neural drive and target oscillations. These results suggest that short-term force-matching skill acquisition is mediated by attenuation of physiological tremor oscillations in the shared synaptic inputs. Supported by simulations, a plausible mechanism for alpha band reductions may involve spinal interneuron phase-cancelling descending oscillations. Therefore, during skill learning, the central nervoussystem acts as a matched filter, adjusting synaptic weights of shared inputs to suppress neuralcomponents unrelated to the specific task

Electrophysiological neuromuscular alterations and severe fatigue predict long-term muscle weakness in survivors of COVID-19 acute respiratory distress syndrome

IntroductionLong-term weakness is common in survivors of COVID-19-associated acute respiratory distress syndrome (CARDS). We longitudinally assessed the predictors of muscle weakness in patients evaluated 6 and 12 months after intensive care unit discharge with in-person visits.MethodsMuscle strength was measured by isometric maximal voluntary contraction (MVC) of the tibialis anterior muscle. Candidate predictors of muscle weakness were follow-up time, sex, age, mechanical ventilation duration, use of steroids in the intensive care unit, the compound muscle action potential of the tibialis anterior muscle (CMAP-TA-S100), a 6-min walk test, severe fatigue, depression and anxiety, post-traumatic stress disorder, cognitive assessment, and body mass index. We also compared the clinical tools currently available for the evaluation of muscle strength (handgrip strength and Medical Research Council sum score) and electrical neuromuscular function (simplified peroneal nerve test [PENT]) with more objective and robust measures of force (MVC) and electrophysiological evaluation of the neuromuscular function of the tibialis anterior muscle (CMAP-TA-S100) for their essential role in ankle control.ResultsMVC improved at 12 months compared with 6 months. CMAP-TA-S100 (P = 0.016) and the presence of severe fatigue (P = 0.036) were independent predictors of MVC. MVC was strongly associated with handgrip strength, whereas CMAP-TA-S100 was strongly associated with PENT.DiscussionElectrical neuromuscular abnormalities and severe fatigue are independently associated with reduced MVC and can be used to predict the risk of long-term muscle weakness in CARDS survivors