The estimation of body center of mass kinematics in sport: proposal of a new protocol

The assessment of body Center of Mass (CoM) kinematics is an important measure in the analysis of sport movements since it is strictly related to balance and stability control [1]. Among the methods proposed to estimate CoM displacement, Segmental method appears to be suitable to investigate CoM kinematics in sport: human body is assumed as a system of rigid segments, and the whole-body CoM is calculated as the weighted average of the CoM of each segment. Each segment is defined by a set of landmarks, and their overall number represents a crucial choice in the protocol design process, being a compromise between accuracy and invasivity [2]. In the present study, using a motion capture system, we validated a protocol based upon the Segmental method, adopting a 14-landmarks anatomical model. Two sets of experiments were made. At first, our protocol was compared to the Ground Reaction Force method (GRF), accounted as a golden standard in CoM estimation. Subsequently, we investigated the aerial phase typical of many sports, comparing our protocol with: (1) an absolute reference, the parabolic regression of the vertical CoM trajectory during the time of flight; (2) two common approaches to estimate CoM kinematics in gait, known as Sacrum and Reconstructed Pelvis methods. Recognized accuracy indexes proved that the results obtained were comparable to the GRF; what is more, during the aerial phase our protocol showed to be significantly more accurate than the other two methods. The protocol assessed can therefore be adopted as a reliable tool for CoM kinematics estimation in further sport researches

Body center of mass displacements during walking with low- and high-heeled shoes

Walking is a natural activity that is very often performed wearing shoes. Among many other kinds of footwear, high-heeled shoes induce increased ankle plantar flexion, greater knee flexion, anterior pelvic tilt, and trunk extension [1]. The modifications in the arrangement of body segments cause an altered position of the body centre of mass (CoM). In the current study, we quantitatively compared the 3D displacement of CoM during flat-heeled and high-heeled gait. Eleven volunteer women (mean age, 24 years) walked wearing either low-heeled and high-heeled shoes (minimum height, 70 mm). On each subject, the 3D coordinates of 14 body landmarks were recorded by an optoelectronic motion analyzer. The body was segmented in 10 independent masses: head, torso, two upper arms and two lower arms (upper body); two upper legs and two lower legs (lower body). Using mean anthropometric data, the whole body CoM was computed, as well as its superior (uCoM) and inferior (iCoM) components [2]. The body CoM was evaluated during normalized stride cycles. High-heeled gait, compared to flat-heeled gait, had a significantly lower CoM at Right heel strike (p=0.024) and Left heel strike (p=0.030). The same findings were also observed for uCoM and iCoM. No significant differences were found at Right toe off. In addition, a significant forward displacement of the iCoM in high-heeled gait was observed at each of the three stages (R heel strike, p=0.017; L heel strike, p=0.034; R toe off, p=0.003). Similar results were found for the whole CoM (p=0.024, p=0.038, p=0.004). The uCoM in high-heeled gait, instead, was significantly more anterior than in flat-heeled gait only at R toe off (p=0.024). Our findings confirmed that wearing high-heeled shoes significantly alters the normal displacement of both components of the human CoM

Italian physical fitness decline: A true fact or a mindset? a 10-year observational perspective study

Evidence regarding a putative physical fitness decline remains less well documented for Italian children and adolescents. An update review of data collection articles was undertaken concerning motor performances (power, strength, speed-agility and indirect cardiorespiratory fitness) of children and adolescents worldwide and compared with 2859 11–12-year-old Italian students of both sexes, throughout a ten-year observational period. Lower limb explosive strength (standing broad jump), flexibility (sit-and-reach), endurance (Cooper) and speed (SP-30) performances of sixth grade Italian students showed nearly stable trends, with no differences during the observed decade, in both sexes. This 10-year perspective study confirmed that Italian physical fitness levels flatlined rather than actually declined. According to these study data, the decline in physical fitness of the Italian youth is ostensible and needs a further in-depth analysis

Cardiorespiratory fitness assessment using the PREFIT test in Italian children: A preliminary dataset

BACKGROUND: The cardiorespiratory fitness (CRF) is one of the most important indicators of the health-related physical fitness components because it reflects the efficiency of the cardiovascular and respiratory systems. To indirectly assess CRF, the original protocol of the 20mSRT was adapted in a new version suitable for children called 20mSRT-PREFIT, providing performances comparable to the standards of the European area. In fact, CRF normative values are missing in the Italian context and therefore they would be meaningful to be assessed. We aimed to determine CRF from 20mSRT-PREFIT in a small sample of Italian pre-school children and to compare the outcomes with the available European references. METHODS: A convenience sample of 5-year-old pre-school children (N.=32, M/F ratio: 19/13) was freely recruited from a kindergarten of the northwest Italy. Children performed the 20mSRT-PREFIT and the number of full shuttles, exhaustion time, and maximum speed were collected to obtain CRF. RESULTS: Predicted VO2max was similar between Italian male and female groups. All other outcomes originating from the 20mSRT-PREFIT were consistent with those included in the available European databases. CONCLUSIONS: According to these preliminary indications, Italian pre-school children may have a CRF level equivalent to that one ascertained in other European countries. Thus, current rakings should be cautiously scrutinized, as they might inappropriately underrate Italian children’s performances

On the Stability of Amorphous Silicon Temperature Sensors

This article investigates the stability of hydrogenated amorphous silicon (a-Si:H) p-i-n junctions employed as temperature sensors in lab-on-chip (LoC) applications. The devices have been tested under forward current injection and different temperatures (from room temperature up to 90 °C) in order to reproduce the practical operating conditions. Two sets of devices with different diborane concentrations in the p-doped layer have been investigated as a case study. For both sets, a temperature-drift error of 0.05 °C/h and a sensitivity around 3 mV/°C in the range between 30 °C and 90 °C have been achieved. These results demonstrate the device suitability as a thin-film temperature sensor integrated into LoC systems that implement thermal treatment of the biological samples as, for example, DNA amplification

In search of a biological pattern for human longevity: Impact of apo A- IV genetic polymorphisms on lipoproteins and the hyper-Lp(a) in centenarians

We studied centenarians to investigate the biological basis of human longevity focusing on the apolipoprotein A-IV and lipoprotein(a); potentially involved in the susceptibility to atherogenic mechanisms. We analyzed two restriction polymorphisms, HinfI347 (alleles +, -)and Fnu4HI360 (alleles 1, 2), and a VNTR (alleles 3, 4) at the 3' region of the apo A-IV gene. The allele frequencies, the lipoprotein concentrations and their association in centenarians and adults have been compared. In centenarians, the Hinfl genotype distribution is different (P<0.05) and the (+ 13) haplotype is prevalent (0.54 vs. 0.39), with a greater association of (+ 3), indicating the selection of a favourable allele. The lipoprotein modulation by the apo A, IV polymorphisms is suggested by significant associations in adults ((+ / +) homozygotes have lower LDL-cholesterol and apo B than heterozygotes; (1/1) homozygotes have higher TG and apo B than heterozygotes), that in centenarians still exists as a trend. Centenarians show peculiar lipoprotein features: lower LDL-cholesterol (mean 103 vs. 115 mg/dl; P < 0.02), and higher lipoprotein(a) (median 17.5 vs. 4.5; P < 0.002). Large part of them (47%), especially the Hinf(+ / +) and the (+ 13) homozygotes, have a lipoprotein(a) > 20 mg/dl, value considered as the threshold for atherogenic risk, surprisingly compatible with healthy longevity