Giovanni Michielon

New Television Technique for Natural Head and Body Posture Analysis

A new television technique that proved to be faster than conventional photographic analysis has been developed and applied to the evaluation of the head and body natural standing posture in 303 healthy children, ages 6 to 11, and in 186 healthy young adults. In the lateral plane all subjects had extended head (soft tissue Frankfurt plane), with parallel Campers and occlusal planes. The neck was halfway between the horizontal and vertical planes. Most angles significantly correlated with each other. The occlusal and neck angles showed a significant effect of age, being larger in children than in adults. In children the neck was more flexed, and the occlusal plane was more inclined downward. The results were in accord with previous photographic evaluations showing that the applied method was reliable and could be usefully employed in postural investigations. The results also confirmed that in healthy subjects, regardless of age, the soft tissue Frankfurt plane is extended, not horizontal.

Morning or evening training: effect on heart rate circadian rhythm

Twenty male endurance athletes (aged 20–25 years) carried out 2-hour daily training sessions, every day from Monday to Friday, for an overall period of 4 weeks. Four different weekly training time table (09.00-11.00; 11.00-13.00; 16.00-18.00; 18.00-20.00 hours) were followed, changing the time slot each week. Each athlete trained, in turn, in each period. The fifth day of each week, heart rate was monitored for 24-28 hours. Statistical analysis employed the single and mean cosinor methods. The heart rate (HR) circadian rhythm was statistically significant (p<0.05) in all 4 training session time. The HR acrophase is progressively postponed during the afternoon: the heart rate acrophase for training done between 18.00 and 20.00 is delayed by approximately 3 hours compared to that of the training done between 09.00 and 11.00. Training done at different daily times synchronizes the HR circadian rhythm. Temporal programming of physical activity is a tool capable of modifying the temporal structure of physiological variables. This approach can be of great interest for coaches who plan training programs and it may benefit athletes when time zone adjustment is an issue, such as transferring to a different continent for a competitive event.

Evaluation of foot support in rugby players: a baropodometric analysis

Intense sports practice has effects on normal locomotion which may predispose athletes to certain injuries. The aim of the study was to evaluate weather playing rugby can change the distribution of forces on the surface of the foot plantar region and if these possible changes are caused by the high loading and the postural stances that this sport involves. The evaluation was performed using a baropodometer in static and dynamic conditions. We studied a group of 23 professional rugby players (scrums and three-quarters) who regularly trained 4-times per week. A control group consisted of 17 non-athletic healthy subjects. Baropodometric analysis revealed significantly higher rear-foot surface area and pressure for both feet in static conditions in rugby players compared to controls. In dynamic conditions, rugby players exerted a significantly higher ground pressure with respect to controls. Within the group of rugby players, scrums had significantly higher pressure than three-quarters, as well as a pressure increase in the lateral foot area. We conclude that rugby players tend to adopt an unbalanced posture posteriorly. The higher ground pressure together with the prevalent load on the lateral foot area may be associated with a difficult control of foot stability, possibly due to the higher body weight and to the increased tone and trophism of the triceps surae subsequent to the various athletic gestures that the game demands. In agreement with the literature, the variations of foot support observed in rugby players may be associated with adaptations induced by this sport, thus favoring an increased risk of bone, joint and muscle traumas and pathologies.

Prevalence of a characteristic gene profile in high-level rhythmic gymnasts

Abstract High-level physical performance in rhythmic gymnastics is influenced by numerous skills and anthropometric factors. In order to understand if genetic predisposition could play a role to define the elite rhythmic gymnast phenotype, we analysed the frequency of common polymorphisms linked to genes correlated with body mass (ADRB2 and FTO), explosive strength (ACTN3 and ACE), and joint mobility (COL5A1), in 42 gymnasts involved in National and International events, and in 42 control girls. Our results demonstrated that high-level rhythmic gymnasts constituted a genetically selected population showing higher frequency of: (a) ADRB2 and FTO alleles linked to low body mass index and low fat mass; (b) COL5A1 CT genotype linked to high joint mobility and to the occurrence of genu recurvatum, but also to a higher incidence of injuries. ACTN3 and ACE polymorphisms did not appear to be connected with the phenotype of high-level rhythmic gymnast. Based on these data, it can be assumed that these polymorphisms could positively affect the phenotype and performance of gymnasts.

Sport–related peripheral nerve injuries: part 1

AbstractInjury in the lower limbs is extremely frequent in most sport activities, particularly when prolonged running and physical contact are prominent features. A major challenge is the differential diagnosis between muscle, joint and nerve lesions, although it should always be considered that combined lesions are quite frequent. In this part of the review, the most frequent nerve entrapment and traumatic lesions involving the peripheral nerves in the lower limb are discussed.

Interpretation and perception of slow, moderate, and fast swimming paces in distance and sprint swimmers.

This study assessed how accurately professional swimmers can interpret instructions to swim “slow,” “moderate,” and “fast.” 8 distance swimmers (6 males, 2 females; M age = 19 yr., SD = 3) and 8 sprint swimmers (7 males, 1 female; M age = 18yr., SD = 1) performed an all-out 50-m crawl stroke and three sets of 8 × 50-m crawl stroke trials interpreting the coachs instruction to swim at slow, moderate, and fast paces. No differences were detected between groups in absolute speed. Nevertheless, distance and sprint swimmers significantly differed in speed normalized to their own 50-m all-out speed (effect sizes = 6.72, 6.20, 1.35 for slow, moderate, and fast, respectively), stroke frequency (effect sizes = 0.81, 1.12, 1.54, respectively), and blood lactate concentration (effect sizes = 0.99, 2.56, 1.70, respectively).

Protective role of 17-β-estradiol towards IL-6 leukocyte expression induced by intense training in young female athletes

Abstract Exercise performed at a competitive level could deeply modify the immune system and the cytokine response of athletes. In this report, we demonstrated that young elite female artistic gymnasts (n = 16; age: 9–15 years) showed an increase of interleukin 6 (IL-6) and tumour necrosis factor alpha (TNF-α) mRNA expression in blood mononuclear cells (PBMCs), in comparison to girls performing the same sport at a recreational level (n = 16; age: 10–15 years). The increase of IL-6 and TNF-α mRNAs appeared to be directly linked to the intensity and duration of the training. Moreover, in elite athletes engaged in artistic gymnastics or in synchronised swimming (n =34; age: 9–15 years), IL-6 gene expression appeared to be modulated by the levels of circulating oestrogens: pre-pubertal athletes (n = 20; age: 11 ± 1 years) revealed a higher increase in IL-6 than pubertal athletes (n = 14; age: 14 ± 1.6 years). In pre-pubertal athletes, body mass index (BMI) percentile was inversely correlated with the increase of both IL-6 and TNF-α. The consequence of these events was the shift of the cytokine profile towards a pro-inflammatory status. These modifications, induced by training performed at an elite level, might negatively affect the growth of female children athletes.

Correlation between two propulsion efficiency indices in front crawl swimming

In front crawl, stroke length (SL) and stroke rate (SR) are two important technical determinants of performance. The relationship between these parameters has been investigated by several authors and two propulsion efficiency indices have been proposed to assess improvements of the front crawl stroke effectiveness in swimmers. The stroke index (SI), proposed by Costill in 1985, relates the velocity (v) and the SL as shown in the following equation: SI=SL v; while the propelling efficiency of the arm stroke, proposed by Zamparo et al. in 2005, relates v, SR and the shoulder-to-hand distance of the arm (l) following the equation: ηp=((0.9 v)/2π SF l) 2/π. The aim of this study was to assess whether the two indices were correlated in two groups (M, males; F, females) of young expert front crawl swimmers, in order to utilise both of them as interchangeable tools when evaluating improvements in propulsion efficacy. The participants performed a 400-m trial, and analyses were carried out for the overall performance as well as for each 100-m section of the 400 m (S1, S2, S3, S4), underlining also a possible gender difference. All the correlations found were significant (p<0.01). The correlation coefficients were lower in M than in F for the overall 400-m trial (R=0.74; R=0.83, respectively) and for each 100-m section (M, R=0.76, R=0.73, R=0.67, R=0.71 for S1, S2, S3 and S4, respectively; F, R=0.84, R=0.84, R=0.79, R=0.83 for S1, S2, S3 and S4, respectively). Since the correlations are not constant throughout the trial, it seems that fatigue affects the two indices differently as well as males and females. Particularly, female swimmers kept more homogeneous stroke parameters, although their performances were lower than the male counterpart. In conclusion, both indices can be used as a device for monitoring the propulsion efficiency in front crawl in our groups of young swimmers, but further studies are needed to better explain how fatigue affects both SI and ηp, especially in the last phases of the performance.

Effects of knee extension with different speeds of movement on muscle and cerebral oxygenation

Background One of the mechanisms responsible for enhancing muscular hypertrophy is the high metabolic stress associated with a reduced muscular oxygenation occurring during exercise, which can be achieved by reducing the speed of movement. Studies have tested that lowered muscle oxygenation artificially induced by an inflatable cuff, could provoke changes in prefrontal cortex oxygenation, hence, to central fatigue. It was hypothesized that (1) exercising with a slow speed of movement would result in greater increase in cerebral and greater decrease in muscle oxygenation compared with exercises of faster speed and (2) the amount of oxygenation increase in the ipsilateral prefrontal cortex would be lower than the contralateral one. Methods An ISS Imagent frequency domain near infrared spectroscopy (NIRS) system was used to quantify oxygenation changes in the vastus lateralis muscle and prefrontal cortex (contra- and ipsilateral) during unilateral resistance exercises with different speeds of movement to voluntary fatigue. After one maximal repetition (1RM) test, eight subjects performed three sets of unilateral knee extensions (∼50% of 1RM), separated by 2 min rest periods, following the pace of 1 s, 3 s and 5 s for both concentric and eccentric phases, in a random order, during separate sessions. The amount of change for NIRS parameters for muscle (ΔHb: deoxyhemoglobin, ΔHbO: oxyhemoglobin, ΔHbT: total hemoglobin, ΔStO2: oxygen saturation) were quantified and compared between conditions and sets by two-way ANOVA RM. Differences in NIRS parameters between contra- and ipsilateral (lobe) prefrontal cortex and conditions were tested. Results Exercising with slow speed of movement was associated to larger muscle deoxygenation than normal speed of movement, as revealed by significant interaction (set × condition) for ΔHb (p = 0.01), and by significant main effects of condition for ΔHbO (p = 0.007) and ΔStO2 (p = 0.016). With regards to the prefrontal cortex, contralateral lobe showed larger oxygenation increase than the ipsilateral one for ΔHb, ΔHbO, ΔHbT, ΔStO2 in each set (main effect of lobe: p < 0.05). Main effects of condition were significant only in set1 for all the parameters, and significant interaction lobe × condition was found only for ΔHb in set1 (p < 0.05). Discussion These findings provided evidence that speed of movement influences the amount of muscle oxygenation. Since the lack of oxygen in muscle is associated to increased metabolic stress, manipulating the speed of movement may be useful in planning resistance-training programs. Moreover, consistent oxygenation increases in both right and left prefrontal lobes were found, suggesting a complementary interaction between the ipsi- and contralateral prefrontal cortex, which also seems related to fatigue.