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This study aimed to compare neuromuscular fatigability of the elbow flexors and extensors between athletes with amputation (AMP) and athletes with spinal cord injury (SCI) for maximum voluntary force (MVF) and rate of force development (RFD). We recruited 20 para-athletes among those participating at two training camps (2022) for Italian Paralympic veterans. Ten athletes with SCI (two with tetraplegia and eight with paraplegia) were compared to 10 athletes with amputation (above the knee, N = 3; below the knee, N = 6; forearm, N = 1). We quantified MVF, RFD at 50, 100, and 150 ms, and maximal RFD (RFDpeak) of elbow flexors and extensors before and after an incremental arm cranking to voluntary fatigue. We also measured the RFD scaling factor (RFD-SF), which is the linear relationship between peak force and peak RFD quantified in a series of ballistic contractions of submaximal amplitude. SCI showed lower levels of MVF and RFD in both muscle groups (all p values ≤ 0.045). Despite this, the decrease in MVF (Cohen's d = 0.425, p < 0.001) and RFDpeak (d = 0.424, p = 0.003) after the incremental test did not show any difference between pathological conditions. Overall, RFD at 50 ms showed the greatest decrease (d = 0.741, p < 0.001), RFD at 100 ms showed a small decrease (d = 0.382, p = 0.020), and RFD at 150 ms did not decrease (p = 0.272). The RFD-SF decreased more in SCI than AMP (p < 0.0001). Muscle fatigability impacted not only maximal force expressions but also the quickness of ballistic contractions of submaximal amplitude, particularly in SCI. This may affect various sports and daily living activities of wheelchair users. Early RFD (i.e., ≤50 ms) was notably affected by muscle fatigability. [ABSTRACT FROM AUTHOR]

Background: Physical activity could increase the production of oxidative stress biomarkers, affecting the metabolism and excretion of antiretroviral drugs and, consequently, the clinical outcome. Nowadays, people living with HIV (PLWH) are mostly switching from triple to dual therapy, but no data are available in terms of physical functioning and oxidative stress. The aim of this study was to evaluate if some antioxidant biomarkers and physical functioning tests could be different according to triple or dual antiretroviral therapy. Methods: PLWH were evaluated at baseline (BL), while treated with three drugs, and six months after the switch to dual therapy. Physical functioning was quantified using validated tools. Mitochondrial and cytosol antioxidant molecules were evaluated through liquid chromatography. Results: Twenty-five patients were analyzed. A statistically significant difference between triple and dual therapy was found for mitochondrial glutathione, but not for physical tests. Evaluating differences between physically active and inactive individuals, the following statistically significant differences were suggested, considering triple therapy (mitochondrial n-formyl-methionine p = 0.022, triglycerides p = 0.023) and double therapy (mitochondrial glycine p = 0.035, cytosol glutamic acid p = 0.007, cytosol s-adenosylmethionine p = 0.021). Conclusions: For the first time, this study suggests possible differences in terms of antioxidant molecules and physical functioning in PLWH switching from triple to dual therapy. [ABSTRACT FROM AUTHOR]

The neural drive to the muscle is the primary determinant of the rate of force development (RFD) in the first 50 ms of a rapid contraction. It is still unproven if repetitive rapid contractions specifically impair the net neural drive to the muscles. To isolate the fatiguing effect of contraction rapidity, 17 male adult volunteers performed 100 burst‐like (i.e., brief force pulses) isometric contractions of the knee extensors. The response to electrically‐evoked single and octet femoral nerve stimulation was measured with high‐density surface electromyography (HD‐sEMG) from the vastus lateralis and medialis muscles. Root mean square (RMS) of each channel of HD‐sEMG was normalized to the corresponding M‐wave peak‐to‐peak amplitude, while muscle fiber conduction velocity (MFCV) was normalized to M‐wave conduction velocity to compensate for changes in sarcolemma properties. Voluntary RFD 0–50 ms decreased (d = −0.56, p < 0.001) while time to peak force (d = 0.90, p < 0.001) and time to RFDpeak increased (d = 0.56, p = 0.034). Relative RMS (d = −1.10, p = 0.006) and MFCV (d = −0.53, p = 0.007) also decreased in the first 50 ms of voluntary contractions. Evoked octet RFD 0–50 ms (d = 0.60, p = 0.020), M‐wave amplitude (d = 0.77, p = 0.009) and conduction velocity (d = 1.75, p < 0.001) all increased. Neural efficacy, i.e., voluntary/octet force ratio, largely decreased (d = −1.50, p < 0.001). We isolated the fatiguing impact of contraction rapidity and found that the decrement in RFD, particularly when calculated in the first 50 ms of muscle contraction, can mainly be explained by a decrease in the net neural drive. [ABSTRACT FROM AUTHOR]

Purpose: To evaluate if the internal training load (ITL; Edwards heart rate [HR]-based and session-rating of perceived exertion [RPE] methods) is affected by the presession well-being perception, age, and position in elite (ie, Serie A2) female volleyball training. Methods: Twelve female elite volleyball players (age: 22 [4] y, height: 1.80 [0.06] m, body mass: 74.1 [4.3] kg) were monitored using an HR monitor during 32 team training sessions (duration: 1:36:12 [0:22:24], in h:min:s). Linear mixed-effects models were applied to evaluate if well-being perception (ie, perceived sleep quality/disorders, stress level, fatigue, and delayed-onset muscle soreness) may affect ITL depending on age and tactical position. Results: Presession perceived fatigue influenced ITL according to the session-RPE (P =.032) but not according to the Edwards method. Age was inversely correlated to the Edwards method (P <.001) and directly correlated to the session-RPE (P =.027). Finally, central blockers experienced a higher training load than hitters (P <.001) and liberos (P <.001) for the Edwards method, as well as higher than hitters (P <.001), liberos (P =.003), and setters (P =.008) for session-RPE. Conclusions: Findings indicated that female volleyball players' perceived ITL is influenced by presession well-being status, age, and position. Therefore, coaches can benefit from this information to specifically predict players' ITL in relation to their individual characteristics. [ABSTRACT FROM AUTHOR]

Purpose: The present study aimed to verify if practicing tackles during rugby union training sessions would affect the players' internal training load and acute strength loss. Method: A total of 9 male Italian Serie A rugby union players (age: 21 [2] y) were monitored by means of an integrated approach across 17 sessions, 6 with tackles (WT) and 11 with no tackles (NT). Edwards training load was quantified using heart-rate monitoring. Global positioning system devices were used to quantify the total distance and time at >20 W. Work-to-rest ratio was quantified by means of a video analysis. Before (PRE) and after (POST) the session, the players' well-being and rating of perceived exertion were measured, respectively. The countermovement jump and plyometric push-up jump tests were performed on a force plate to record the players' PRE--POST concentric peak force. Linear mixed models were applied to quantify the differences between WT and NT in terms of training load and PRE--POST force deltas, even controlling for other training factors. Results: The Edwards training load (estimated mean [EM]; standard error [SE]; WT: EM = 214, SE = 11.8; NT: EM = 194, SE = 11.1; P = .01) and session rating of perceived exertion (WT: EM = 379, SE = 21.9; NT: EM = 277, SE = 16.4; P < .001) were higher in WT than in NT. Conversely, no difference between the sessions emerged in the countermovement jump and plyometric push-up concentric peak force deltas. Conclusions: Although elite rugby union players' external and internal training load can be influenced by practicing tackles, upper- and lower-limb strength seem to not be affected. [ABSTRACT FROM AUTHOR]

We aimed to quantify the prevalence of track and field sprinters competing at a world-class level in more than one discipline, and we describe the career characteristics of single- and double-discipline athletes in terms of peak performance and the age of peak performance. The career performance of athletes ranked in the top 200 positions of the World Athletics database in the 100 m, 200 m, and 400 m were analyzed, i.e., 5514 career profiles (49.9% female). Using binomial proportion, we calculated how many competed in only one or more than one discipline. We also compared the peak performance and the age of peak performance of athletes who competed in one vs. more than one discipline. Independent of gender, about 50% of the athletes competing in the 100 m and 200 m also competed in the other discipline (i.e., 200 m and 100 m, respectively). Differently, only 20% of the athletes competing in the 400 m also competed in the 200 m. Sprinters competing in the 100–200 m and 200–400 m couples showed better peak performance than the sprinters competing in only one discipline. Many world-class sprinters compete in two disciplines, and the 100–200 m was the most prevalent couple. Our results also suggest that sprinters who compete in two disciplines may be advantaged compared to sprinters who compete in only one event. [ABSTRACT FROM AUTHOR]

Walking and running are based on rapid burst‐like muscle contractions. Burst‐like contractions generate a Gaussian‐shaped force profile, in which neuromuscular determinants have never been assessed. We investigated the neural and contractile determinants of the rate of force development (RFD) in burst‐like isometric knee extensions. Together with maximal voluntary force (MVF), voluntary and electrically evoked (8 stimuli at 300 Hz, octets) forces were measured in the first 50, 100, and 150 ms of burst‐like quadriceps contractions in 24 adults. High‐density surface electromyography (HDsEMG) was adopted to measure the root mean square (RMS) and muscle fiber conduction velocity (MFCV) from the vastus lateralis and medialis. The determinants of voluntary force at 50, 100, and 150 ms were assessed by stepwise multiple regression analysis. Force at 50 ms was explained by RMS (R2 = 0.361); force at 100 ms was explained by octet (R2 = 0.646); force at 150 ms was explained by MVF (R2 = 0.711) and octet (R2 = 0.061). Peak RFD (which occurred at 60 ± 10 ms from contraction onset) was explained by MVF (R2 = 0.518) and by RMS50 (R2 = 0.074). MFCV did not emerge as a determinant of RFD. Muscle excitation was the sole determinant of early RFD (50 ms), while contractile characteristics were more relevant for late RFD (≥100 ms). As peak RFD is mostly determined by MVF, it may not be more informative than MVF itself. Therefore, a time‐locked analysis of RFD provides more insights into the neuromuscular characteristics of explosive contractions. [ABSTRACT FROM AUTHOR]

Background: Frailty is a well-known condition that leads to a lack of resilience, with a reduced homeostatic capacity and a consequent higher risk of suffering adverse health outcomes. This study investigated the effectiveness of an exercise program to improve and reverse physical frailty amongst Italian older adults. Methods: One hundred and twenty-three community dwelling older adults (mean age 74 years, SD = 6; 64% women) were involved in an experimental (EG; n = 62) and a control (CG; n = 61) group. Frailty was assessed at baseline and after the intervention using an adapted version of the frailty phenotype. The EG took part in a 16-week exercise program, consisting of endurance, strength, balance and flexibility exercises, while the CG maintained the same routine. Results: After the exercise program, the EG was more robust than the CG (F = 43.51, p < 0.001). Within the EG, 46% of pre-frail and 50% of frail people reached the robust and pre-frail levels, respectively. Effects of training were higher in frail and pre-frail people (reduction of frailty of 0.67 and 0.76 points, respectively) compared to robust ones (who frailty levels increased by 0.23 points; F = 11.32, p < 0.001). Conclusions: A multicomponent exercise program may be effective at improving and reverting frailty, specifically for frail and pre-frail people. [ABSTRACT FROM AUTHOR]

The present study aimed to determine a cut-off value following the filling in of a questionnaire (PAQ-C-It) to identify active Italian children. One-hundred-twenty-nine primary school children (5 Piedmont schools; 47.3% female; mean age = 10 ± 1 years) wore an accelerometer (Actigraph wGT3X-BT) to objectively quantify individual moderate-to-vigorous physical activity during one week. Afterwards, the PAQ-C-It was filled in by participants. A ROC curve procedure was applied to obtain an active/non-active cut-off point. Spearman's correlation coefficient was also applied to establish the relationship between the two parameters. According to the ROC analysis, the PAQ-C-It cut-off point value is identifiable at >2.75 to indicate active children (area under the curve = 0.62; standard error = 0.05; p = 0.025; coefficient intervals = 0.518–0.716; sensitivity = 0.592, specificity = 0.382), determining that 65 participants (55%) were non-active (mean PAQ-C-It value = 2.3 ± 0.4; active mean PAQ-C-It value = 3.3 ± 0.4). Spearman's correlation coefficient results were significant but with a small effect size (rho = 0.214; p = 0.008). In conclusion, the present results suggest that the PAQ-C-It can be cautiously used as tool to practically classify active Italian children because of a non-solid relationship between respective accelerometer data and MVPA daily data. [ABSTRACT FROM AUTHOR]

Because rate of force development (RFD) is an emerging outcome measure for the assessment of neuromuscular function in unfatigued conditions, and it represents a valid alternative/complement to the classical evaluation of pure maximal strength, this scoping review aimed to map the available evidence regarding RFD as an indicator of neuromuscular fatigue. Thus, following a general overview of the main studies published on this topic, we arbitrarily compared the amount of neuromuscular fatigue between the "gold standard" measure (maximal voluntary force, MVF) and peak, early (≤100 ms) and late (>100 ms) RFD. Seventy full-text articles were included in the review. The most-common fatiguing exercises were resistance exercises (37% of the studies), endurance exercises/locomotor activities (23%), isokinetic contractions (17%), and simulated/real sport situations (13%). The most widely tested tasks were knee extension (60%) and plantar flexion (10%). The reason (i.e., rationale) for evaluating RFD was lacking in 36% of the studies. On average, the amount of fatigue for MVF (−19%) was comparable to late RFD (−19%) but lower compared to both peak RFD (−25%) and early RFD (−23%). Even if the rationale for evaluating RFD in the fatigued state was often lacking and the specificity between test task and fatiguing exercise characteristics was not always respected in the included studies, RFD seems to be a valid indicator of neuromuscular fatigue. Based on our arbitrary analyses, peak RFD and early phase RFD appear even to be more sensitive to quantify neuromuscular fatigue than MVF and late phase RFD. [ABSTRACT FROM AUTHOR]

Purpose: The present study aimed to investigate the actual and wished supports to promote a successful dual career for Italian student-athletes. Methods: An ad hoc questionnaire (nine items) was administered to 711 academic Italian student-athletes (age = 23 ± 4 years). A binomial regression for categorical outcomes was applied to discriminate subcategories for each item. Results: According to the items which could be considered as more related to the actual and wished supports to promote a successful dual career, student-athletes mostly answered that tutoring (≤ 24 years old, 95%, OR 3.55; team, 95%, OR 2.27; elite, 97%, OR 3.33; not sport science path, 93–96%, OR range 3.45–7.69), e-learning (last year, 95%, OR 1.97), and extra-academic merits (team, 71%, OR 1.47; elite, 77%, OR 2.13) resulted as not satisfactorily supported by university, but highly wished by student-athletes. Also the flexibility in lesson frequency and exam sustainability resulted as strongly considered, but perceived as limited (≤ 24 years old, 84%, OR 2.43; Medical and Humanistic, 87%, with respect to Sport Science path, OR 9.01). In addition, in terms of identity, female (68%, OR 2.22), > 24 years old (68%, OR 2.22), sub-elite (68%, OR 2.22), not sport science (57–65%, OR 2.48–2.03), and last year of attendance (62%, OR 3.45) participants showed to be more student-oriented, whereas elite (60%), sport science path (61%), and out of course (56%) student-athletes perceived themselves as mainly athletic-oriented. Conclusion: Italian student-athletes could be better supported by University in complying sport and academic requirements, especially by means of an improvement in tutoring, e-learning and a more flexible schedule, in line with the European Commission guidelines. [ABSTRACT FROM AUTHOR]

Purpose: The present study aimed to investigate dual-career issues of Italian student-athletes according to gender, age, type of sport, competition level, university path, and year of attendance variables to highlight their main problems and solutions. Methods: An ad hoc 24-item questionnaire was administered to 711 academic Italian student-athletes (Mean age = 23; SD = 4 years). A multivariate analysis was applied for data related to the first 21 (section A), whereas answers from the last 3 items (section B) were only described. Results: For section A items, two factors (factor 2: items 5, 7, 8, 14; Cronbach alpha = 0.728; factor 5: items 10, 11; Cronbach alpha = 0.78) related to sport participation and education for future job emerged. For both factors, effects emerged between "year of attendance" subcategories (i.e., lower values for "out of course" subgroup), whereas only for factor 5, differences emerged in terms of age (i.e., higher values for younger than older subgroup). For section B, most student-athletes declared to wish schedules of lessons and exams (e.g., higher number of sessions; oral online interrogations) for better combining sport and academic requirements. Conclusion: The present study represents a further step to better understand the Italian student-athletes' daily and weekly limitations and wished solutions related to the combination of sport and academic tasks. Institutional bodies should consider the present findings in case of future policies in supporting dual career. [ABSTRACT FROM AUTHOR]

Conflicting results have been reported on whether closed kinetic chain exercises (such as a leg press) may induce more balanced activation of vastus medialis (VM) and lateralis (VL) muscles compared with open kinetic chain exercise (such as pure knee extension). This study aimed to 1) compare between-vasti motor unit activity and 2) analyze the combined motor unit behavior from both muscles between open and closed kinetic chain exercises. Thirteen participants (four women, mean ± SD age: 27 ± 5 yr) performed isometric knee extension and leg press at 10, 30, 50, 70% of the maximum voluntary torque. High density surface EMG signals were recorded from the VM and VL and motor unit firings were automatically identified by convolutive blind source separation. We estimated the total synaptic input received by the two muscles by analyzing the difference in discharge rate from recruitment to target torque for motor units matched by recruitment threshold. When controlling for recruitment threshold and discharge rate at recruitment, the motor unit discharge rates were higher for knee extension compared with the leg press exercise at 50% [estimate = 1.2 pulses per second (pps), standard error (SE) = 0.3 pps, P = 0.0138] and 70% (estimate = 2.0 pps, SE = 0.3 pps, P = 0.0001) of maximal torque. However, no difference between the vasti muscles were detected in both exercises. The estimates of synaptic input to the muscles confirmed these results. In conclusion, the estimated synaptic input received by VM and VL was similar within and across exercises. However, both muscles had higher firing rates and estimated synaptic input at the highest torque levels during knee extension. Taken together, the results show that knee-extension is more suitable than leg-press exercise at increasing the concurrent activation of the vasti muscles. NEW & NOTEWORTHY There is a significant debate on whether open kinetic chain, single-joint knee extension exercise can influence the individual and combined activity of the vasti muscles compared with closed kinetic chain, multijoint leg press exercise. Here we show that attempting to change the contribution of either the vastus medialis or vastus lateralis via different forms of exercise does not seem to be a viable strategy. However, the adoption of open kinetic chain knee extension induces greater discharge rate and estimated synaptic input to both vasti muscles compared with the leg press. [ABSTRACT FROM AUTHOR]

The relative age effect (RAE) is a common phenomenon observed in youth sports and is characterized by a significant over-representation of athletes born close to the date of selection. However, there is a lack of research on RAE in world-class track and field athletes and it is not clear if this effect persists into adulthood. Thus, this study examined for the first time the prevalence and magnitude of RAE at world class level in all track and field disciplines. Birthdates of 39,590 athletes (51.6% females) ranked in the International Association of Athletics Federations top 100 official lists between 2007 and 2018 season of Under 18, Under 20, and Senior categories were collected. Under 18 and Under 20 athletes born in the first week of the year are about 2 to 3.5 times more likely to be included in the top-100 ranking than the athletes born in the last week of the year. RAE was overall larger in male compared to female athletes. In some disciplines (e.g., throwing events) RAE persists in Senior category. These findings suggest that in some disciplines relatively younger athletes may have less chances of reaching world-class performances even in the adulthood. Governing bodies should reflect upon their policies for athlete support and selection to minimize the RAE. [ABSTRACT FROM AUTHOR]

Background: Frailty is a clinical condition among older adults defined as the loss of resources in one or more domains (i.e., physical, psychological and social domains) of individual functioning. In frail subjects emergency situations and mobility levels need to be carefully monitored. This study aimed to: i) evaluate differences in the mobility index (MI) provided by ADAMO system, an innovative remote monitoring device for older adults; ii) compare the association of the MI and a traditional physical measure with frailty.Methods: Twenty-five community-dwelling older adults (71 ± 6 years; 60% women) wore ADAMO continuously for a week. The time percentage spent in Low, Moderate and Vigorous Activities was assessed using ADAMO system. Walking ability and frailty were measured using the 400 m walk test and the Tilburg Frailty Indicator, respectively.Results: Controlling for age and gender, the ANCOVA showed that frail and robust participants were different for Low (frail = 58.8%, robust = 42.0%, p < 0.001), Moderate (frail = 25.5%, robust = 33.8%, p = 0.008), and Vigorous Activity (frail = 15.7%, robust = 24.2%, p = 0.035). Using cluster analysis, participants were divided into two groups, one with higher and one with lower mobility. Controlling for age and gender, linear regression showed that the MI clusters were associated with total (β = 0.571, p = 0.002), physical (β = 0.381, p = 0.031) and social (β = 0.652, p < 0.001) frailty; and the 400 m walk test was just associated with total (β = 0.404, p = 0.043) and physical frailty (β = 0.668, p = 0.002).Conclusion: ADAMO system seems to be a suitable time tracking that allows to measure mobility levels in a non-intrusive way providing wider information on individual health status and specifically on frailty. For the frail individuals with an important loss of resources in physical domain, this innovative device may represent a considerable help in preventing physical consequences and in monitoring functional status. [ABSTRACT FROM AUTHOR]

Background: The evaluation of electrocortical activity (EEG) during visual stimuli may reveal differences depending on experience level.Methods: Fourteen volunteers, seven belonging to the expert group (high experience in the field of the acrobatic gymnastics) and seven to the control one, took part in the study. Ten videos recorded during the execution of specific physical movements of acrobatic gymnastics have been included in the execution task. Power spectrum as indicator of the electrocortical activity was used.Results: Expert group showed lower power spectra levels in delta (MD = − 2.23) and higher power spectra levels in slow alpha (MD = 2.17) bands, compared to control group during the vision of the videos with errors; during the vision of the videos without errors, expert group showed lower power spectra levels in delta (MD = − 1.04) and higher power spectra levels in slow alpha (MD = 1.88) bands compared to control group. Generally, occipital, frontal and central areas showed differences between groups in regard to power spectra levels.Conclusions: These findings confirm the relationship between EEG activity and vision of specific physical movements and extend knowledge on the electrocortical response to visual stimuli emphasizing the difference between experienced and inexperienced subjects, relative to the field analyzed. [ABSTRACT FROM AUTHOR]

Evaluating the rate of torque development (RTD) in isometric ballistic contraction targeting submaximal torques is usually overlooked in the literature. In a series of isometric ballistic contractions targeting a range of submaximal torque values, there is a linear relationship between the peak torque and the peak RTD obtained in each contraction. RTD scaling factor (RTD-SF) represents the slope of this relationship. In this study, we investigated the prevalence of interlimb asymmetry in the RTD-SF and in the RTD calculated across submaximal torques. Furthermore, we compared these asymmetry indices with those calculated adopting more classical approaches, such as ballistic contraction targeting maximal torque and isokinetic concentric conditions. Quadriceps and hamstrings strength was evaluated in both limbs of elite under 17 and under 19 soccer players (20 males, 17 ± 1 years). Participants performed three concentric isokinetic contractions at 240°/s and a series of isometric ballistic contractions targeting from 20 to 100% of maximal isometric torque. The interlimb difference was calculated for each parameter and players presenting an interlimb difference >15% were identified. A total of 40% (for quadriceps) and 60% (for hamstring) of players showed an interlimb asymmetry in isometric RTD for at least 50% of submaximal torque range. The RTD-SF was able to identify more players with asymmetry than the classical isokinetic tests. However, isokinetic and isometric indices of asymmetry were in general poorly or not correlated with each other. Most players presented an interlimb asymmetry in RTD for a wide part of the torque range and the adopted protocol was able to highlight important interindividual differences. Furthermore, players showed a large prevalence of RTD-SF asymmetry in both quadriceps and hamstrings. It is still to be determined if these asymmetries are functionally relevant. Nevertheless, the adopted protocol provided meaningful information for identifying interlimb asymmetries that could not be gathered when adopting the classical method of ballistic contractions targeting only maximal torques. [ABSTRACT FROM AUTHOR]

The effect of muscle fatigue on rate of force development (RFD) is usually assessed during tasks that require participants to reach as quickly as possible maximal or near-maximal force. However, endurance sports require athletes to quickly produce force of submaximal, rather than maximal, amplitudes. Thus, this study investigated the effect of muscle fatigue induced by long-distance running on the capacity to quickly produce submaximal levels of force. Twenty-one male amateur runners were evaluated before and shortly after a half-marathon race. Knee extensors force was recorded under maximal voluntary and electrically evoked contractions. Moreover, a series of ballistic contractions at different submaximal amplitudes (from 20 to 100% of maximal voluntary force) was obtained, by asking the participants to reach submaximal forces as fast as possible. The RFD was calculated for each contraction. After the race, maximal voluntary activation, resting doublet twitch, maximal force, and RFD during maximal contraction decreased (-12, -12, -21, and -19%, respectively, all P -values < 0.0001). Nevertheless, the RFD values measured during ballistic contractions up to 60% of maximal force were unaffected (all P -values > 0.4). Long-distance running impaired the capacity to quickly produce force in ballistic contractions of maximal, but not of submaximal, amplitudes. Overall, these findings suggest that central and peripheral fatigue do not affect the quickness to which muscle contracts across a wide range of submaximal forces. This is a relevant finding for running and other daily life activities that rely on the production of rapid submaximal contractions rather than maximal force levels. [ABSTRACT FROM AUTHOR]

The motivation to perform physical activity is a crucial factor in achieving a persistent active lifestyle. However, motivation decreases with increasing age from childhood to adolescence. The promotion of physical activity in educational settings might be an important tool to increase motivation and, consequently, to decrease sedentary behavior. The aim of this study was to explore the effect of a 4-month school-based walking intervention on motivation to participate in physical activity among Italian middle-school students. This study included 276 students (mean age 13 ± 1 years, 41.3% female). A total of 138 students (intervention group) participated in a brief walking intervention that was added to their routine daily school activity, while a convenience sample of 138 students performed the routine daily school activity. The activity consisted of walking one kilometer outside of school buildings during the morning break. Motivation data were collected before and after the walking breaks using the Participation Motivation Questionnaire (PMQ). Controlling for age, significant interactions between group and time were observed in the “Social Status” [F(1,273) = 4.851; p = 0.028], “Team” [F(1,273) = 6.015; p = 0.015] and “Energy Release” components [F(1,273) = 8.527; p = 0.038]. Specifically, a significant decrease in the “Social Status” components of the PMQ and an increase in the “Team” and “Energy Release” components were observed in the intervention group. On the contrary. control group showed an increase in “Social Status” and a decrease in the “Team” and “Energy Release” components. Within this developmental context, incorporation of the walking activity helped to modify the motivational orientation towards physical activity to include more intrinsic factors, which were related to the possibility of remaining with classmates and peer groups and releasing a surplus of energy. [ABSTRACT FROM AUTHOR]

Brief bouts of physical activity during the school day are an innovative method for increasing physical activity in the school setting. The purpose of the study was to investigate if the introduction of an outdoor active break, based on walking and running, in a middle school in Italy is feasible in terms of implementation (i.e., adherence, costs, safety) and acceptability (i.e., satisfaction, intent to continue use, perceived appropriateness). One hundred and forty students (aged 12 ± 1 years) and 20 teachers (aged 50 ± 8 years) participated in the activity for four months. The activity consisted of walking (or running) one kilometer outside the school buildings during the mid-morning. Data from questionnaires regarding the satisfaction with and the acceptability of the activity were collected. The activity was safely performed three to four days a week, without any costs to the school or to students’ parents. Students and teachers were satisfied with the activity (positive answers from 95% and 89% of each group, respectively). Moreover, the teachers reported that the program was easy to organize and did not negatively influence their teaching activities. The intervention was easily and safely implemented, and it was considered suitable for the daily routine of an Italian middle school. Further studies are needed to examine its impact on physical activity levels and academic achievement. [ABSTRACT FROM AUTHOR]

Women are known to be less fatigable than men in single-joint exercises, but fatigue induced by running has not been well understood. Here we investigated sex differences in central and peripheral fatigue and in rate of force development (RFD) in the knee extensors after a half-marathon run. Ten male and eight female amateur runners (aged 25-50 years) were evaluated before and immediately after a half-marathon race. Knee extensors forces were obtained under voluntary and electrically evoked isometric contractions. Maximal voluntary isometric contraction (MVC) force and peak RFD were recorded. Electrically doublet stimuli were delivered during the MVC and at rest to calculate the level of voluntary activation and the resting doublet twitch. After the race, decreases in MVC force (males: −11%, effect size [ES] 0.52; females: −11% ES 0.33), voluntary activation (males: −6%, ES 0.87; females: −4%, ES 0.72), and resting doublet twitch (males: −6%, ES 0.34; females: −8%, ES 0.30) were found to be similar between males and females. The decrease in peak RFD was found to be similar between males and females (males: −14%, ES 0.43; females: −15%, ES 0.14). Half-marathon run induced both central and peripheral fatigue, without any difference between men and women. The maximal and explosive strength loss was found similar between sexes. Together, these findings do not support the need of sex-specific training interventions to increase the tolerance to neuromuscular fatigue in half-marathoners. [ABSTRACT FROM AUTHOR]

The relative age effect (RAE; i.e., an asymmetry in the birth distribution) is a bias observed in sport competitions that may favour relatively older athletes in talent identification. Therefore, the aim of this study was to investigate the presence of RAE in elite soccer players competing in the Italian championships, even considering the discriminations of younger and older Serie A players (in relation to the median age of the sample), and different positional roles (i.e., goalkeeper, defender, midfielder, forward) for each observed category. A total of 2051 players competing into the 2017–2018 Italian under-15 (n = 265), under-16 (n = 362), under-17 (n = 403), Primavera (n = 421) and Serie A (n = 600) championships were analysed. The birth-date distributions, grouped in four quartiles (i.e., January-March, Q1; April-June, Q2; July-September, Q3; October-December, Q4), were compared to a uniform distribution using Chi-squared analysis. The week of birth was analysed using Poisson regression. The results showed a large over-representation of players born in Q1 in all soccer player categories. However, the effect size of this trend resulted smaller as age increased. Individuals born in Q1 have about two-folds more chances to become a Serie A player compared to those born in Q4. The Poisson regression analysis showed that RAE was greater for defenders than for forwards among all categories. Therefore, a strongly biased selection emerged among elite soccer players competing in Italian championships, highlighting how young individuals born in the first three months have many more chances to become elite players compared to the others. [ABSTRACT FROM AUTHOR]

Due to poling action and upper body engagement, Nordic walking (NW) has additional health benefits with respect to conventional walking. The aim of this study was to evaluate the differences in muscle activation and metabolic responses between NW, performed with the technique suggested by NW instructors, and with some modifications in the way to move upper limb and poles. Ten NW instructors volunteered to walk on a treadmill at 5.5 km•h-1 in five conditions: walking (W), Nordic walking (NW), NW with a weak poling action (NWweak), with straight-upper limbs moving the shoulders (NWshoulder) and with elbow flexion-extension pattern and shoulder freezed (NWelbow). Poling forces, body segments and poles movement, upper and lower body muscle activation, as well as metabolic parameters were measured.All modified NW techniques elicited lower muscular activation and metabolic responses with respect to the suggested NW technique (P < 0.05). All NW techniques elicited higher muscular activation and metabolic responses than W. All parameters observed with the NWweak were lower than NW. A decreased activation of shoulder extensor muscles and increased activation of anterior deltoid muscle were the main features of NWshoulder. Lower triceps brachii muscle activation and reduced propulsive poling action with respect to NW were seen for NWelbow, resulting also in shorter steps.Nordic walking instructors, sport technicians and practitioners should be aware that any deviation from the technique usually suggested might lead to lower benefits. However it is worth to note that any walking technique with poles elicits higher metabolic responses and muscular activation than walking. [ABSTRACT FROM AUTHOR]

Background: Accurate measurement devices are required to objectively quantify physical activity. Wearable activity monitors, such as pedometers, may serve as affordable and feasible instruments for measuring physical activity levels in older adults during their normal activities of daily living. Currently few available accelerometer-based steps counting devices have been shown to be accurate at slow walking speeds, therefore there is still lacking appropriate devices tailored for slow speed ambulation, typical of older adults. This study aimed to assess the validity of step counting using the pedometer function of the ADAMO Care Watch, containing an embedded algorithm for measuring physical activity in older adults. Methods: Twenty older adults aged ≥ 65 years (mean ± SD, 75±7 years; range, 68–91) and 20 young adults (25±5 years, range 20–40), wore a care watch on each wrist and performed a number of randomly ordered tasks: walking at slow, normal and fast self-paced speeds; a Timed Up and Go test (TUG); a step test and ascending/descending stairs. The criterion measure was the actual number of steps observed, counted with a manual tally counter. Absolute percentage error scores, Intraclass Correlation Coefficients (ICC), and Bland–Altman plots were used to assess validity. Results: ADAMO Care Watch demonstrated high validity during slow and normal speeds (range 0.5–1.5 m/s) showing an absolute error from 1.3% to 1.9% in the older adult group and from 0.7% to 2.7% in the young adult group. The percentage error for the 30-metre walking tasks increased with faster pace in both young adult (17%) and older adult groups (6%). In the TUG test, there was less error in the steps recorded for older adults (1.3% to 2.2%) than the young adults (6.6% to 7.2%). For the total sample, the ICCs for the ADAMO Care Watch for the 30-metre walking tasks at each speed and for the TUG test were ranged between 0.931 to 0.985. Conclusion: These findings provide evidence that the ADAMO Care Watch demonstrated highly accurate measurements of the steps count in all activities, particularly walking at normal and slow speeds. Therefore, these data support the inclusion of the ADAMO Care Watch in clinical applications for measuring the number of steps taken by older adults at normal, slow walking speeds. [ABSTRACT FROM AUTHOR]

The present study aimed to investigate motivations for the dual career of Italian student-athletes attending different university courses. For this purpose, the Italian Harmonized version of the Student-athletes' Motivation toward Sports and Academics Questionnaire (SAMSAQ-IT/A) was administered to 760 Italian student-athletes. Exploratory Factor Analysis (EFA) and Cronbach's alpha coefficients were applied to test the factor structure and the reliability of the SAMSAQ-IT/A, respectively. Furthermore, the Confirmatory Factor Analysis (CFA) assessed the fit of the model. A multivariate approach was applied to verify subgroups effects ( P ≤ 0.05) in relation to gender (i.e., female, male), competition level (i.e., elite, sub-elite), type of sport (i.e., individual sport, team sport, disciplines performed both as individual and team), educational area (i.e., economical/law, humanistic, mathematics/engineering, medical, movement/sport sciences), and year of attendance (i.e., Bachelor 1st, 2nd, 3rd year, Master degree 1st and 2nd year, off course). EFA highlighted a three-factor model (i.e., Sport Motivation, SM; Academic Motivation, AM; Dual Career Motivation, CM) with acceptable reliability estimates (SM = 0.93; AM = 0.85; CM = 0.90) and good CFA indexes. Furthermore, differences between subgroups were found for gender (SM, P = 0.02; AM, P = 0.007), type of sport (AM, P = 0.039), competition level (SM, P < 0.001; CM, P = 0.004), educational area (SM, P = 0.003; AM, P = 0.001; CM, P < 0.001), and year of attendance (AM, P = 0.005; CM, P = 0.002). In conclusion, SAMSAQ-IT/A demonstrated to be a useful tool and results showed that Italian student-athletes' motivation for dual career has to be specifically investigate according to gender, age, competition level, type of sport, educational area, and year of attendance. [ABSTRACT FROM AUTHOR]

Background: Changes in electrocortical activity during motor imagery are among the most interesting findings in the recent neuroscientific studies; existing studies, however, do not focus specifically on Alpha and Beta rhythms, in relationship with the motor experience and verifying if the style of music can influence the cortical activity during motor imagery task. Power spectra analysis was used to compare the EEG activity during dance imagery tasks in a group of dancers and in a control group. Methods: Twenty-one volunteers performed a dance imagery task listening to three kinds of music. For EEG acquisition an 8-channel headset with wireless amplifier was used. This study used independent component analysis (ICA) to assess EEG frequency spectrum associated with the musical genre. High Alpha (10.0-11.5 Hz) and Low Beta (12.0-15.5 Hz) EEG frequency spectra were analyzed. Considering EEG power spectra analysis, no statistically significant differences were found between groups at baseline. Results: Statistically significant difference ( p < 0.01) emerged comparingthe two groups, during dance imagery task, listening to Classical, Rock and Waltz music, in High Alpha band; whereas listening to Classical music in Low Beta band. Expert group showed a greater power level with respect to control group for both bands. No statistically significant difference emerged in EEG power spectrum, comparing the three kinds of music, for both groups (intra-group analysis). Findings are comparable with previous studies obtained by other neuroimaging modalities, highlighting how high-resolution EEG may prove to be a promising tool for measuring cortex electrical activity during motor imagery. This study successfully applied ICA to decompose the EEG segments recorded during the tasks, finding consistent independent brain processes across multiple subjects. Conclusions: The statistically significant differences between expert dancers and controls, could indicate a difference in the attentional effort during the dance imagery task. The remarks partially confirm existing findings on the relationship among EEG activity, Alpha rhythm and motor imagery and also extend the knowledge on the EEG response to auditory stimuli during motor imagery in particular for Beta rhythm components, emphasizing specific characteristics in function of the level of familiarity to the dance imagery task. [ABSTRACT FROM AUTHOR]

Purpose: Relative age effect (RAE) is a bias usually observed in young athletes and in academia, where participation is higher among those born early in the year. We aimed to determine RAE in undergraduate students of sport science. Methods: The birth dates of a sample of undergraduate students ( N = 11,280) at the University of Torino (Italy) were collected. Students belonged to sport science ( N = 5229) and other faculties ( N = 6051; law, arts, and economics). All students were divided into four groups depending on their birth date, and the distribution of the birth dates was compared with the general population by means of Chi square test. Results: The observed distribution was different from that expected for male undergraduate students of sport science ( P = 0.009), where most students were born in the first few months of the year. Differently, in female students of sport science and students belonging to other faculties, the birth dates were more normally distributed ( P > 0.05). Conclusion: In conclusion, we observed a skewed distribution of the birth dates in male, but not in female, undergraduate students of sport science. Probably, the physical advantages of the young males born at the year beginning may have oriented the choice of sport science degree, an academic field where physical capacities provide some advantages. [ABSTRACT FROM AUTHOR]

Background: Whole-body electromyostimulation (WB-EMS) has become increasingly popular under the promise to offer a time-saving and effective exercise protocols. Few studies estimating the training intervention intensity of WB-EMS are available in the literature. Aim: The aim of this study was first to estimate the metabolic demand and muscle fatigue induced by a training session with WB-EMS, and second to compare them to a control intervention. Methods: Ten young participants performed two training sessions: an experimental condition constituted by five exercises with superimposed WB-EMS and a control condition constituted by five body weight exercises. Both sessions lasted 15 min and were based on isometric intermittent contraction (6 of contraction interspersed by 4 s of rest). Muscle fatigue was assessed by determining the force decrease in the following tests: isometric mid-thigh pull; plyometric push-up; counter-movement jump. Oxygen consumption and energy expenditure were recorded by measuring respiratory gases exchange to quantify the metabolic demand of the exercises. Results: The WB-EMS intervention required greater volume of oxygen consumed (WB-EMS 1584 ± 251 ml/min; control 1465 ± 216 ml/min, p = 0.006) and energy expenditure (WB-EMS 470 ± 71 kcal/h; control 438 ± 61 kcal/h, p = 0.013) than in control intervention. Overall, the WB-EMS training induced muscle fatigue (all PRE vs POST tests p ≤ 0.02) whereas the body weight exercises did not (all p > 0.14). Conclusions: These results indicate that WB-EMS intervention constituted a vigorous physical activity. The WB-EMS required also a greater metabolic demand and greater muscle fatigue than a traditional body weight circuit training. Thus, WB-EMS can be considered as an alternative training tool for physically active individuals. [ABSTRACT FROM AUTHOR]

Introduction: The idea that early sport success can be detrimental for long-term sport performance is still under debate. Therefore, the aims of this study were to examine the career trajectories of Italian high and long jumpers to provide a better understanding of performance development in jumping events. Methods: The official long-jump and high-jump rankings of the Italian Track and Field Federation were collected from the age of 12 to career termination, for both genders from the year 1994 to 2014. Top-level athletes were identified as those with a percentile of their personal best performance between 97 and 100. Results: The age of entering competitions of top-level athletes was not different than the rest of the athletic population, whereas top-level athletes performed their personal best later than the rest of the athletes. Top-level athletes showed an overall higher rate of improvement in performance from the age of 13 to the age of 18 years when compared to all other individuals. Only 10–25% of the top-level adult athletes were top-level at the age of 16. Around 60% of the top-level young at the age of 16 did not maintain the same level of performance in adulthood. Female high-jump represented an exception from this trend since in this group most top-level young become top-level adult athletes. Conclusions: These findings suggest that performance before the age of 16 is not a good predictor of adult performance in long and high jump. The annual rate of improvements from 13 to 18 years should be included as a predictor of success rather than performance per se. Coaches should be careful about predicting future success based on performances obtained during youth in jumping events. [ABSTRACT FROM AUTHOR]

The purpose of this paper is twofold: to validate the properties of the Italian version of the Baller Identity Measurement Scale (i.e., BIMS-IT), a self-report questionnaire based on the athletic and academic identities; and to investigate differences in psychosocial factors such as gender, age, type of sport, and competition level. The dimensionality of the BIMS-IT was explored by means of the exploratory factor analysis, considering the scale’s internal consistency too (Confirmatory Factor Analysis). Results related to exploratory and confirmatory factor analysis supported a model of measurement composed of two correlated factors: the athletic and academic identities and affectivity related to identities. For both factors, differences emerged between age, and competition level sub groups. In particular, higher identity scores emerged for ≤ 24 years old student-athletes with respect to their age counterparts. National sub-elite student-athletes reported lower identity values than those of national elite and international levels. Results suggest that the Italian version of the BIMS-IT is psychometrically robust and could be adopted for empirical uses. The higher identity scores reported by younger and higher competition level participants suggest a correspondent higher involvement into the student-athlete role. However, BIMS-IT represents a distinct model with respect to the original American BIMS, determining the need of further research on the student-athletes’ identity to better clarify any socio-cultural contest effects. [ABSTRACT FROM AUTHOR]

Knee extensor and elbow flexor muscles have been demonstrated to have similar fatigability, i.e. time to task failure at submaximal force level, in healthy non-trained individuals. This experiment investigated if continuative endurance training can influence the fatigability of these two muscle groups in amateur runners. Surface electromyography was used to assess fatigability in twelve amateur runners. Participants were requested to sustain for 30 s the 70 % of their maximum voluntary contraction of knee extensor and elbow flexor muscles. During contractions, electromyographic signals were recorded, respectively, from vastus lateralis and biceps brachii muscles with linear array of eight electrodes. Muscle fiber conduction velocity (CV), mean power spectral frequency (MNF), and fractal dimension (FD) of electromyographic signals were calculated. During the sustained contraction vastus lateralis muscle showed smaller decrease of CV ( p = 0.006), MNF ( p = 0.001), and FD ( p = 0.001) than biceps brachii muscle. The lower fatigability found in knee extensors than in elbow flexors suggests that the physiological adaptation promoted by the endurance training was specific to the musculature involved in the training (i.e. the lower limbs). [ABSTRACT FROM AUTHOR]

The aim of this study was to assess the changes in muscle fiber conduction velocity (CV), as a sign of fatigue during knee extensor contraction in patients with chronic obstructive pulmonary disease (COPD) as compared with healthy controls. Eleven male patients (5 with severe and 6 with moderate COPD; age 67 ± 5 years) and 11 age-matched healthy male controls (age 65 ± 4 years) volunteered for the study. CV was obtained by multichannel surface electromyography (EMG) from the vastus lateralis (VL) and medialis (VM) of the quadriceps muscle during isometric, 30-second duration knee extension at 70% of maximal voluntary contraction. The decline in CV in both the VL and VM was steeper in the severe COPD patients than in healthy controls (for VL: severe COPD vs. controls −0.45 ± 0.07%/s;p< 0.001, and for VM: severe COPD vs. controls −0.54 ± 0.09%/s,p< 0.001). No difference in CV decline was found between the moderate COPD patients and the healthy controls. These findings suggest that severe COPD may impair muscle functions, leading to greater muscular fatigue, as expressed by CV changes. The results may be due to a greater involvement of anaerobic metabolism and a shift towards fatigable type II fibers in the muscle composition of the severe COPD patients. [ABSTRACT FROM PUBLISHER]

Neuromuscular assessment of rock climbers has been mainly focused on forearm muscles in the literature. We aimed to extend the body of knowledge investigating on two other upper limb muscles during sport-specific activities in nine male rock climbers. We assessed neuromuscular manifestations of fatigue recording surface electromyographic signals from brachioradialis and teres major muscles, using multi-channel electrode arrays. Participants performed two tasks until volitional exhaustion: a sequence of dynamic pull-ups and an isometric contraction sustaining the body at half-way of a pull-up (with the elbows flexed at 90°). The tasks were performed in randomized order with 10 minutes of rest in between. The normalized rate of change of muscle fiber conduction velocity was calculated as the index of fatigue. The time-to-task failure was significantly shorter in the dynamic (31 ±10 s) than isometric contraction (59 ±19 s). The rate of decrease of muscle fiber conduction velocity was found steeper in the dynamic than isometric task both in brachioradialis (isometric: −0.2 ±0.1%/s; dynamic: −1.2 ±0.6%/s) and teres major muscles (isometric: −0.4±0.3%/s; dynamic: −1.8±0.7%/s). The main finding was that a sequence of dynamic pull-ups lead to higher fatigue than sustaining the body weight in an isometric condition at half-way of a pull-up. Furthermore, we confirmed the possibility to properly record physiological CV estimates from two muscles, which had never been studied before in rock climbing, in highly dynamic contractions. [ABSTRACT FROM AUTHOR]

The aim of this mini-review is to describe the potential application of surface electromyography (sEMG) techniques in aging studies. Aging is characterized by multiple changes of the musculoskeletal system physiology and function. This paper will examine some of the innovative methods used to monitor age-related alterations of the neuromuscular system from sEMG signals. A description of critical assumptions which underlie some of these approaches is emphasized. The first part focuses on the evolution of the recording techniques and describes some methodological issues. The second part focuses on how to use the following techniques to characterize aging: amplitude and spectral sEMG signal analysis, muscle fiber conduction velocity estimation, and myoelectric fatigue assessment. The last part describes a number of advanced sEMG approaches which seem promising in the geriatric population to estimate motor unit number, size, recruitment thresholds, and firing rates. [ABSTRACT FROM AUTHOR]

In order to investigate the behaviour of athletes in choosing sports, we analyse data from part of the We-Sport®database, a vertical social network that links athletes through sports. In particular, we explore connections between people sharing common sports and the role of age and gender by applying “network science” approaches and methods. The results show a disassortative tendency of athletes in choosing sports, a negative correlation between age and number of chosen sports and a positive correlation between age of connected athletes. Some interesting patterns of connection between age classes are depicted. In addition, we propose a method to classify sports, based on the analyses of the behaviour of people practising them. Thanks to this brand new classifications, we highlight the links of class of sports and their unexpected features. We emphasise some gender dependency affinity in choosing sport classes. [ABSTRACT FROM PUBLISHER]

The aim of this mini-review is to describe the potential application of surface electromyography (sEMG) techniques in aging studies. Aging is characterized by multiple changes of the musculoskeletal system physiology and function. This paper will examine some of the innovative methods used to monitor age-related alterations of the neuromuscular system from sEMG signals. A description of critical assumptions which underlie some of these approaches is emphasized. The first part focuses on the evolution of the recording techniques and describes some methodological issues. The second part focuses on how to use the following techniques to characterize aging: amplitude and spectral sEMG signal analysis, muscle fiber conduction velocity estimation, and myoelectric fatigue assessment. The last part describes a number of advanced sEMG approaches which seem promising in the geriatric population to estimate motor unit number, size, recruitment thresholds, and firing rates. © 2014 S. Karger AG, Basel [ABSTRACT FROM AUTHOR]

Purpose: This study presents a method to evaluate the efficacy of the start techniques' biomechanics in swimming using a kinematic reference data-set. Methods: The biomechanics of the start techniques was derived by the performances of ten regional swimmers using a marker-based stereoscopic approach. Three start techniques were analyzed: grab start, rear track start, and front track start. The kinematic reference data-set was compiled from data available from the literature in biomechanics of the high-level swimmers. The evaluating method was based on three parameters: (1) The horizontal component of the dive speed; (2) The angle between the line joining the center of mass of the swimmer with the intersection point of the pool-water plane and the pool edge plane; (3) The distance between the block and the center of mass of the swimmer. Results: Differences ( p < 0.05) in the block position during the start were found between the national swimmers and the references in grab start, front track start, and in rear track start. Before the dive, national swimmers jump up from the block in opposition to the high-level swimmers that drop from the block such as the literature revealed. Conclusions: This study allows: (1) To formulate a model of comparative analysis of data from the literature; (2) To obtain a three-dimensional model of the swimmers using a handy low-cost stereoscopic system; (3) To compare different multi-dimensional biomechanical models designed to describe the diving task. This approach would provide an innovative tool to evaluate the efficacy of the start technique and to assist coaches and trainers to improve their training programs. [ABSTRACT FROM AUTHOR]

Purpose: The aim of the study was to estimate spatial activation of vastus lateralis (VL) muscle during electrical stimulation applied to the entire muscle in absence of fatigue and properly eliminating the influence of stimulation artifact. Methods: Ten healthy men were enrolled in this study. The current was delivered to VL by two electrodes placed proximally and distally, for 5 s at the higher intensity that subjects can tolerate. Superficial electromyography (sEMG) signals were acquired using a bidimensional array of 63 electrodes positioned between the two stimulating electrodes along muscle fibers. For each subjects average rectified value (ARV) was estimated on normalized sEMG signals dividing bidimensional array in two areas, then the barycenter of the more active area was estimated. Finally, average barycenter coordinates were calculated among subjects since Kruskal-Wallis and Dunn-Sidak post hoc test confirmed no statistical differences among subjects in the more active area. Results: ARV analysis showed that the VL more active area was located laterally and distally with respect to the center of the bidimensional array. Mean and standard deviation among subjects revealed that barycenter of more active zone in medio-lateral direction was between electrodes 1 and 2 and in proximal-distal direction was between electrodes 10 and 11. This location corresponds to a well-defined area in the framework of anatomical landmarks defined in the text. Conclusions: It was possible to assess that VL during electrical stimulation was activated differently throughout its volume. In particular, distal-lateral portion of the muscle was more active with respect to the other. [ABSTRACT FROM AUTHOR]