Upper-Limb Muscle Fatigability in Para-Athletes Quantified as the Rate of Force Development in Rapid Contractions of Submaximal Amplitude.

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.

Mitigating against relative age effects in youth Track & Field: Validating corrective adjustment procedures across multiple events.

OBJECTIVES: With the aim to better identify talented Track & Field performance development, this study estimated the relationships between chronological (decimal) age with 60-m sprint, high jump, triple jump, and pole vault performance. Then, to mitigate against expected Relative Age Effects (RAEs), Corrective Adjustment Procedures (CAPs) were applied to an independent sample. DESIGN: Mixed-longitudinal design examining public data between 2005 and 2019. METHODS: The performances of 5339 Italian sprinters and jumpers (53.1 %) spanning 11.01-17.99 years of age were examined, with trendlines between chronological age and performance established. Related to an independent sample (N = 40,306; female 45.5 %), trendlines were then utilised to apply CAPs and adjust individual performance. Considering raw and adjusted performance data, RAE distributions were examined for the top 25 % and 10 % performers. RESULTS: For all male and female events, quadratic models best summarised the relationships between chronological age and performance (R2 = 0.74-0.89). When examining independent athletes in similar event, RAEs were more pronounced in males (Cramer's V = 0.35-0.14) than females (Cramer's V = 0.29-0.07). For both sexes, RAE magnitude decreased with age and increased according to performance level (i.e., Top25%-Top10%). However, following CAP applications, RAEs were reduced or removed within annual age groups and performance levels. CONCLUSIONS: With RAEs prevalent across Italian youth Track & Field events, findings validate CAPs as a strategy to account for the influence of relative age differences on athletic performance. CAPs help establish a more equitable strategy for performance evaluation and could help improve the efficacy of long-term athlete development programming.

Studying the Changes in Physical Functioning and Oxidative Stress-Related Molecules in People Living with HIV after Switching from Triple to Dual Therapy.

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.

Performance pathways in elite middle- and long-distance track and field athletes: The influence of a successful youth.

OBJECTIVES: There is limited information on the performance progression of athletics endurance athletes from junior-to-senior status and the determinants of success in adulthood. This study aimed to quantify the youth-to-senior transition rate, the likelihood of success and the relationship between youth and senior performance amongst world-class athletes competing in middle- and long-distance disciplines. DESIGN: Retrospective design examining public data between 2000 and 2019. METHODS: The performances of 4678 international athletes (45.3 % female) were analysed. World's all-time top 50 athletes were identified for U18 and Senior categories (age ≥ 20 years). Youth-to-senior transition rate and transition probabilities were calculated. Correlations between best U18 and Senior performances were determined to assess the stability of the performance. RESULTS: The youth-to-senior transition rate for top U18 athletes was low for males and females (~19 % and 21 %). Nevertheless, the probability of transition to a top senior was ~7 times higher for top U18 athletes than for non-top U18 athletes. The correlations between youth and senior best performances were low-to-high. CONCLUSIONS: Few top U18 athletes maintained top world ranking status during their senior careers. Still, they are more likely to become top senior athletes than those who did not perform at the top level in U18. The association between youth and senior performance is stronger when comparing the same discipline or when athletes competed over longer distances in their senior compared to U18 career. Being a successful youth athlete may represent a small advantage for future success, however, it does not guarantee advancement to the senior top level.

Decreased neural drive affects the early rate of force development after repeated burst-like isometric contractions.

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.

Impact of active lifestyle on the primary school children saliva microbiota composition.

The aim of the study was to evaluate the effects of Active or Sedentary lifestyle on saliva microbiota composition in Italian schoolchildren. Methods: Male (114) and female children (8-10 years) belonging to five primary schools in the neighborhoods of Turin were classified as active (A) or sedentary (S) based on PAQ-C-It questionnaire. PCR amplification of salivary DNA targeted the hypervariable V3-V4 regions of the 16S rRNA bacterial genes. DADA2 workflow was used to infer the Amplicon Sequence Variants and the taxonomic assignments; the beta-diversity was obtained by PCoA with the UniFrac method; LEfSe algorithm, threshold at 5%, and Log LDA cutoff at ±0.5 were used to identify differently abundant species in A compared to S saliva sample. Daily food intake was assessed by 3-Days food record. The metabolic potential of microbial communities was assessed by PICRUSt. Results: No significant differences were found in individual's gender distribution (p = 0.411), anthropometry, BMI (p > 0.05), and all diet composition between A and S groups (p > 0.05). Eight species were differently abundant: Prevotella nigrescens (LDA score = -3.76; FDR = 1.5×10-03), Collinsella aerofaciens (LDA score = -3.17; FDR = 7.45×10-03), Simonsiella muelleri (LDA score = -2.96; FDR = 2.76×10-05), Parabacteroides merdae (LDA score = -2.43; FDR = 1.3×10-02) are enriched in the A group; Gemella parahaemolysans, Prevotella aurantiaca (LDA score = -3.9; FDR = 5.27×10-04), Prevotella pallens (LDA score = 4.23; FDR = 1.93×10-02), Neisseria mucosa (LDA score = 4.43; FDR = 1.31×10-02; LDA score = 2.94; FDR = 7.45×10-03) are enriched in the S group. A prevalence of superpathway of fatty acid biosynthesis initiation (E. coli) and catechol degradation II (meta-cleavage pathway) was found in saliva from A compared to S children. Conclusion: Our results showed that active children had an enrichment of species and genera mainly associated with a healthier profile. By contrast, the genera and the species enriched in the sedentary group could be linked to human diseases.

Two Is Better than One: Successful World-Class Sprinters Compete in Two Disciplines.

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.

"Stay at Home" during the COVID-19 Pandemic: Effects on Physical Activity and Sedentary Behavior in an Italian Academic Community.

This study investigates changes in physical activity (PA) and sedentary behavior in an Italian university community during Phase 1 of SARS-CoV-2 lockdown ("stay at home" government decree, from March 8th to May 4th, 2020) compared to their habits prior to the COVID-19 pandemic. We also examine differences according to gender, university position, BMI categories, and sport participation. A total of 2596 people (median age 24, IQR 11 years; 70.8% women) filled out a survey after eight weeks of statutory confinement at home. The International Physical Activity Questionnaire measured PA and sedentary behavior in a typical week before and during lockdown. Physically inactive people passed from 10.9% to 35.0% before−during the lockdown. The total amount of PA decreased (median 2307 vs. 1367 MET-min/week; p < 0.001), while sedentary behavior increased (median 349 vs. 440 min/day; p < 0.001) between before and during the lockdown. The following categories showed a higher reduction in the total amount of PA: men when compared to women; people with normal weight when compared to pre-obese/obese people; and people who played sports when compared to those who did not play sports. There is a need to propose PA/exercise programs to counteract physical inactivity and sedentarism during a social emergency, with special attention to people who showed higher PA reduction.

Neural and contractile determinants of burst-like explosive isometric contractions of the knee extensors.

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.

Indoor Mobility, Frailty, and Disability in Community-Dwelling Older Adults: A Mediation Model.

The general population, but especially older adults, were forced or encouraged to stay home during the recent COVID-19 pandemic. In this context, indoor mobility (IM, the number of steps performed daily at home) may be informative about the general health status of older adults. The present study aimed at evaluating the relationship between IM, frailty (loss of functional reserve including both physical and psychosocial domains), and disability (loss of autonomy measured as activities of daily life, ADLs) in a sample of community-dwelling Italian older adults. Specifically, the primary objective was to investigate IM and disability differences between robust and frail older adults. The secondary objective was to test if frailty is in the causal sequence between IM and disability, i.e., as a mediator in their relationship. Thirty-two participants (mean age = 70 ± 6 years; 56.2% women) were recruited. Frailty and disability were evaluated using the Tilburg Frailty Indicator and the Groningen Activity Restriction Scale, respectively. IM at home was measured via an Adamo wristwatch (a connected accelerometer). One-way analyses of covariance, controlling for age and gender, showed that robust participants, classified according to a score higher than five points in the Tilburg Frailty Indicator, performed significantly more IM (F1,28 = 4.639; p = 0.04) and presented lower disability grade than frail ones (F1,28 = 4.342; p =0.046). Only physical frailty was a mediator in the relationship between IM and disability (F2,29 = 8.538, p < 0.001), with a fully mediated model (z = -2.073, p < 0.04). Conversely, the total frailty score was not a mediator in the same relationship, but with IM accounted for the variance in disability (F2,29 = 8.538, p < 0.001; R2 = 33.7%). Our results suggested that frail older adults restricted their IM more and presented a higher level of disability compared to robust older adults. Moreover, data suggest that IM reduction may have a negative impact on physical frailty and indirectly increase disability.

Strength Asymmetries Are Muscle-Specific and Metric-Dependent.

We investigated if dominance affected upper limbs muscle function, and we calculated the level of agreement in asymmetry direction across various muscle-function metrics of two heterologous muscle groups. We recorded elbow flexors and extensors isometric strength of the dominant and non-dominant limb of 55 healthy adults. Participants performed a series of explosive contractions of maximal and submaximal amplitudes to record three metrics of muscle performance: maximal voluntary force (MVF), rate of force development (RFDpeak), and RFD-Scaling Factor (RFD-SF). At the population level, the MVF was the only muscle function that showed a difference between the dominant and non-dominant sides, being on average slightly (3-6%) higher on the non-dominant side. At the individual level, the direction agreement among heterologous muscles was poor for all metrics (Kappa values ≤ 0.15). When considering the homologous muscles, the direction agreement was moderate between MVF and RFDpeak (Kappa = 0.37) and low between MVF and RFD-SF (Kappa = 0.01). The asymmetries are muscle-specific and rarely favour the same side across different muscle-performance metrics. At the individual level, no one side is more performative than the other: each limb is favoured depending on muscle group and performance metric. The present findings can be used by practitioners that want to decrease the asymmetry levels as they should prescribe specific exercise training for each muscle.

Corrective Adjustment Procedures as a strategy to remove Relative Age Effects: Validation across male and female age-group long jumping.

OBJECTIVES: To validate the application of Corrective Adjustment Procedures for removing Relative Age Effects in youth athletic contexts, this study estimated the longitudinal relationships between decimal age (chronological and relative) and performance in male and female long jumpers. Using trendlines, Corrective Adjustment Procedures were applied, and Relative Age Effect distributions associated with performance attainment were re-examined. DESIGN: Retrospective longitudinal design examining competitive long-jump data between 2005 and 2019. METHODS: In Part I, participants were 689 junior Italian long jumpers (age range = 11.01-17.99 years; 56.6% females) who participated in ≥three events. Longitudinal modelling and regression equations quantified the sex-specific relationships between decimal age and long jump performance. In Part II, equations were utilised to adjust individual performance within an independent sample (N = 13,639; 50.1% females) of age-matched jumpers. Relative Age Effect distributions within attainment levels (i.e., Top 25-10%) were examined based on raw and correctively adjusted performance. RESULTS: Irrespective of sex, Relative Age Effects were prevalent across all age-groups with medium-large effect sizes at 12-17 (males and females) and 12-17 years (females) of age (Cramer's V range = 0.07-0.28). Relative Age Effect bias magnitude also increased with attainment level (i.e., Top 25-10%). Following Corrective Adjustment Procedure application, typical Relative Age Effects were removed with non-significant deviations in relative age distributions regardless of sex or age-group or attainment level (Top 25 or 10%). CONCLUSIONS: Findings provide efficacy for Corrective Adjustment Procedure application to remove Relative Age Effects across youth long jumping events. Corrective Adjustment Procedures suggest potential in improving performance evaluation, identification of technically skilled performers, and sporting experiences.

Effects of a Multicomponent Exercise Program on Prevalence and Severity of the Frailty Syndrome in a Sample of Italian Community-Dwelling Older Adults.

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.

The Cut-Off Value for Classifying Active Italian Children Using the Corresponding National Version of the Physical Activity Questionnaire.

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.

Rate of Force Development as an Indicator of Neuromuscular Fatigue: A Scoping Review.

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.

Is fatigue a muscular phenomenon in Parkinson's disease? Implications for rehabilitation.

BACKGROUND: Fatigue in Parkinson's disease (PD) compromises patients' physical activity and poses questions on how to plan correct rehabilitation training. In addition, the relationship between subjective perceived fatigue and fatigue in motor performance is not yet entirely understood. Therefore, a conclusive interpretation of muscular mechanisms of fatigue in PD has not yet been achieved. Among the various instrumental evaluations for fatigue, multichannel surface electromyography (sEMG) is a recognized tool that permits the study of myoelectric manifestations of fatigue. AIM: The aim of this study was to assess if muscles in PD show a different myoelectric fatigue pattern compared to the muscles of healthy age-matched subjects. DESIGN: The design was observational controlled study. POPULATION: Idiopathic Parkinson's Disease, Hohen &Yahr II and III stage, Parkinsonian Fatigue Scale average score ≥2.95, no therapy modification in the 4 weeks preceding the study; exclusion criteria: mini mental state examination ≤24, upper limb disease/symptoms that might interfere with sEMG analysis, presence of other fatigue-related conditions. Twenty patients were selected according to these criteria. Twenty untrained healthy subjects were matched. METHODS: All subjects underwent a muscle fatigue protocol and a sEMG analysis of the right biceps brachii muscle during electrically stimulated and voluntary contractions in order to obtain a myoelectric fatigue muscular pattern. The myoelectric pattern is characterized by the modifications of the following sEMG variables: reduction of mean frequency and muscle fiber conduction velocity, increase of average rectified value. RESULTS: No statistical differences were observed between groups for sEMG variables and muscular electric behavior in all contraction conditions (all P>0.05). CONCLUSIONS: Our results show that parkinsonian muscles do not differ from the muscles of healthy age-matched subjects in developing peripheral myoelectric fatigue. Nevertheless, the role of fatigue perception at rest and particularly during physical activity must be clearly understood in order to further target the rehabilitative approach for fatigued parkinsonian patients and to reduce hypomobility. CLINICAL REHABILITATION IMPACT: In rehabilitative terms, these findings allow us to highlight the possibility of performing sustained training with isometric contractions in PD subjects; therefore, fatigue "per se" does not constitute a barrier for the execution of muscular exercises, likewise intensive.

Relation among Perceived Weight Change, Sedentary Activities and Sleep Quality during COVID-19 Lockdown: A Study in an Academic Community in Northern Italy.

In Italy, COVID-19 lockdown was imposed from 8 March until 3 May 2020 with negative consequences on the lifestyles and health of people. Within this context, the paper aims: (i) to analyse the impact of COVID-19 lockdown on perceived weight changes; (ii) to evaluate factors associated with the perception of weight changes (Body Mass Index (BMI), sleep quality, time spent in sedentary activities), in an Italian academic community of students and workers. A total of 3666 participants took part in this cross-sectional study (2838 students and 828 workers, of whom 73.0% were female). T-test, Chi-square test and the two-way ANOVA were used. Results showed that 43.3% of participants perceived a weight gain. Workers experienced a more substantial increase in body weight (0.7 kg) compared to students (0.3 kg; p = 0.013). A significant difference between preobese/obese workers (0.9 kg) and students (-0.3 kg; p < 0.001) was found. Overall, 57.0% of the sample was characterized by high levels of sedentary activities. Sedentary people noticed a higher weight gain (0.4 kg) compared to less sedentary people (0.3 kg; p = 0.048). More than 45% of participants reported a worsening of sleep quality and showed a perceived increase in body weight (0.5 kg) in comparison to those who improved their sleep quality (no weight change; p = 0.001). Designing tailored interventions to promote health-related behaviours during lockdown periods is essential.

Subjective versus Objective Measure of Physical Activity: A Systematic Review and Meta-Analysis of the Convergent Validity of the Physical Activity Questionnaire for Children (PAQ-C).

This study aimed to highlight the relationship between moderate-to-vigorous physical activity (MVPA) as assessed by accelerometer devices and the Physical Activity Questionnaire for Children (PAQ-C) to estimate the convergent validity of the questionnaire. A systematic review and a meta-analysis were applied by collecting pertinent studies (PubMed, Web of Science, PsycINFO, and SCOPUS) from 1997 until November 2020. The relationship between PAQ-C and MVPA scores was estimated considering correlation coefficients such as the effect size. Fisher's transformation was used to convert each correlation coefficient into an approximately normal distribution. The pooled correlations between PAQ-C and MVPA scores were measured by r values after converting the Fisher's z values back into correlation coefficients for presentation. A total of 13 studies were included in the meta-analysis, and a random effects model was adopted. The pooled correlation between PAQ-C and MVPA scores was significant but with a moderate effect size (r = 0.34 [0.29, 0.39], Z = 15.00, p < 0.001). No heterogeneity among the studies was observed (I2 < 25%). In conclusion, the results highlighted a moderate relationship (around 0.30-0.40) between PAQ-C and accelerometer measurements. These results suggested to concurrently administer both tools to reach a more comprehensive description of children's PA, in terms of quality and quantity.

Effects of Presession Well-Being Perception on Internal Training Load in Female Volleyball Players.

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.

Internal-Training-Load Monitoring, Notational and Time-Motion Analyses, Psychometric Status, and Neuromuscular Responses in Elite Rugby Union.

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.