Acute effects of static stretching and proprioceptive neuromuscular facilitation on non-local range of movement.

Acute effects of static stretching (SS) and proprioceptive neuromuscular facilitation (PNF) on local and non-local range of motion (ROM) were assessed in 29 participants. Three evaluations were performed one week apart: week-1 Control session (CS); weeks 2-3 either SS or PNF interventions (randomized). Dominant and non-dominant limbs, local (hamstring extensibility) and non-local ROMs (Shoulder extension-ShE) were collected at baseline (T0), immediately after (T1), and fifteen minutes post-intervention (T2). No differences were found between time-points during the CS. Local-ROM significantly increased (p=0.0002, ES=0.74 and 0.0079, 0.56, for dominant and non-dominant lower limbs, respectively) after both SS and PNF. No interaction between time and treatment was detected for ShE in both limbs. However, post-hoc analysis revealed a significant increase in dominant upper limb ShE between T0 and T1 only after SS (p=0.002; +6.5%). Acute bouts of SS and PNF can increase local-ROM, however, no clear effects were observed for non-local ROM.

Relationship between Lifestyle Determinants and Perceived Mental and Physical Health in Italian Nursery and Primary School Teachers after the COVID-19 Lockdown.

The COVID-19 lockdown and the consequent distance school learning made epochal changes in children's lifestyles; however, little is known about the lockdown effects on school teacher habits. The aim of this observational study is to examine differences in the lifestyle of nursery (NS) and primary (PS) school teachers after one of the COVID-19 lockdowns and investigate the relationship between perceived physical/mental health and demographics, weight status and lifestyle determinants, such as adherence to the Mediterranean Diet (MD) and physical activity level (PAL). A total sample of 265 participants (49.22 ± 6.95 years) filled out an online information questionnaire and standardized questionnaires to collect data on the Physical Component Summary (PCS), Mental Component Summary (MCS), PAL and MD-adherence. A t-test or ANOVA analysis was used to assess differences between quantitative variables: Mann-Whitney U or Kruskal-Wallis tests for qualitative variables. Spearman's correlations and multinomial logistic regression analyses were performed to identify categorical factors associated with classes of PCS and MCS. Teachers showed sufficient/high PAL, with a significantly higher level in the PS group (p < 0.05). This last showed a higher PCS score (p < 0.05). No differences between groups were found for MD-adherence, which was moderate/fair in both groups, and MCS, which was sufficient/good. Logistic regression showed that the only positive predictor of a high PCS was being physically active (OR 2.10, 95%CI 1.05-4.2, p < 0.05), while MCS was positively associated with normal weight status (OR 0.48, 95%CI 0.33-0.78, p = 0.020). This study highlights that PS teachers are more active than the NS group and perceive a higher physical health level. Mere predictors of physical and mental well-being are PA practice and being normal weight, respectively. This suggests that interventions to improve perceived health in this work category should be focused on the promotion of physical activity practice and on the maintenance of an optimal weight status.

Sex differences in the determination of prescribed load in ballistic bench press.

Introduction: The objectives of the present study were twofold: first, to identify the specific relative load at which the concentric motion transforms into a purely propulsive action among women, and second, to compare the load-velocity relationships between men and women during the bench press throw. Methods: Fourteen men and fourteen women participated in a test where they progressively increased the load until reaching their one-repetition maximum (1RM) in the bench press exercise. Linear regression models were employed to elucidate the relationships between load and velocity, as well as load and the propulsive phase (% of total concentric time). Additionally, ANCOVA was utilized to compare the linear regression models between men and women. Results: The results revealed strong and linear associations between load and mean propulsive velocity (MPV) for both men and women, as well as between load and the propulsive phase. Notably, there were significant differences in MPV and the propulsive phase concerning load between men and women. Women transitioned into a fully propulsive concentric phase at approximately 80% of their 1RM, while men achieved this entirely propulsive phase at around 85% of their 1RM. Furthermore, women exhibited reduced velocities when handling lighter relative loads compared to men. Conversely, women demonstrated higher velocities when dealing with loads exceeding 85% of their 1RM in contrast to their male counterparts. Discussion: These findings hold notable implications for prescribing bench press throw loads for women, which should differ from those recommended for men. Further studies are necessary to validate the efficacy of the proposed load recommendations.

Acute effects of different administration order of stretching exercises: effects on range of motion and cross-over effect.

BACKGROUND: The aim of this manuscript is to investigate if stretching exercise administration order may influence outcomes pertinent to range of movement (ROM). METHODS: A total sample of 108 participants was randomized into five groups. Eight sets of unilateral static stretching (SS) of 30s duration each with a 30s rest were administered to the right leg. One group underwent SS of the knee extensors (KE), another to the knee flexors (KF), another first to the KE and then to the KF, another first to the KF and then to the KE while the last group was used as control (CG). Each group was assessed for ROM of both lower limbs for either the KE and KF motion (passive hip extention [PHE] and passive straight leg raise [PSLR], respectively). Measures were assessed before (T0), immediately after (T1), and 15 minutes after the intervention (T2). RESULTS: No differences were observed for time (T0 vs. T1 vs. T2) for all measures in the CG for both limbs. Time-x-group interactions were observed only in the intervention limb (P<0.0007 and 0.004, ES 0.73 and 0.55, for KE and KF, respectively). Within the intervention limb, a significant increase in the PHE was observed from T0 to T1 only in the KE and KF/KE groups. For measures of the PSLR, a significant increase was observed from T0 to T1 only in the KF and KE/KF groups. No differences neither for time or group were observed in the control limb. CONCLUSIONS: Our results highlight that exercise administration order has an effect on ROM outcomes. Measures of ROM significantly increase only for the last stretched muscle in each intervention group. No crossover effect was observed in the contralateral limb.

Relationship between external and internal load indicators and injury using machine learning in professional soccer: a systematic review and meta-analysis.

This study verified the relationship between internal load (IL) and external load (EL) and their association on injury risk (IR) prediction considering machine learning (ML) approaches. Studies were included if: (1) participants were male professional soccer players; (2) carried out for at least 2 sessions, exercises, or competitions; (3) correlated training load (TL) with non-contact injuries; (4) applied ML approaches to predict TL and non-contact injuries. TL included: IL indicators (Rating of Perceived Exertion, RPE; Session-RPE, Heart Rate, HR) and EL indicators (Global Positioning System, GPS variables); the relationship between EL and IL through index, ratio, formula; ML indicators included performance measures, predictive performance of ML methods, measure of feature importance, relevant predictors, outcome variable, predictor variable, data pre-processing, features selection, ML methods. Twenty-five studies were included. Eleven addressed the relationship between EL and IL. Five used EL/IL indexes. Five studies predicted IL indicators. Three studies investigated the association between EL and IL with IR. One study predicted IR using ML. Significant positive correlations were found between S-RPE and total distance (TD) (r = 0.73; 95% CI (0.64 to 0.82)) as well as between S-RPE and player load (PL) (r = 0.76; 95% CI (0.68 to 0.84)). Association between IL and EL and their relationship with injuries were found. RPE, S-RPE, and HR were associated with different EL indicators. A positive relationship between EL and IL indicators and IR was also observed. Moreover, new indexes or ratios (integrating EL and IL) to improve knowledge regarding TL and fitness status were also applied. ML can predict IL indicators (HR and RPE), and IR. The present systematic review was registered in PROSPERO (CRD42021245312).

Lower limb muscle activation pattern in male soccer players with lumbar hyperlordosis.

OBJECTIVE: the aim of the current study was to compare the lower limb muscle activation pattern in soccer players with and without lumbar hyperlordosis during single-leg squat performance. METHODS: thirty male collegiate soccer players (15 with and 15 without lumbar hyperlordosis) performed the SLS task. Surface EMG was used to record the activation of eleven lower limb muscles. The activation of these muscles reduces to 100 points during the SLS cycle, where 50% demonstrates the maximum knee flexion, and 0% and 99% demonstrate the maximum knee extension. RESULTS: soccer players with lumbar hyperlordosis had higher muscle activation than those with normal lumbar lordosis in gluteus maximus, biceps femoris, and medial gastrocnemius. By contrast, they had lower gluteus medius, vastus medialis oblique, rectus femoris, soleus, and medial gastrocnemius (only in the final ascent phase of the SLS) muscle activity than the normal group during the SLS. CONCLUSION: this alteration may negatively affect targeted muscle performance during the SLS. Subsequent study is required to specify whether such an alteration in the lower limb muscle could be accompanied by injury in soccer players and change in their athletic performance.

Functional fitness, lifestyle and demographic factors as predictors of perceived physical and mental health in older adults: A structural equation model.

Over the past 50 years, socioeconomic development has brought a reduction in birth rates, an increase in life expectancy and consequently in the elderly population. For this reason, there has been an increasing focus on physical and mental health of the elderly, promoting the concept of healthy aging. The aim of this study was to explore the associations between perceived physical and mental health of older adults and a variety of determinants, such as demographic factors, physical functional fitness, physical activity level, adherence to the Mediterranean diet and anthropometric indices, through a structural equation modeling (SEM). A cross-sectional observational study involved 208 elderly (24 men and 184 women) over the age of 60, fully independent and autonomous. Perceived physical and mental health were assessed with the Short Form 12 questionnaire. Basic sociodemographic information was collected; anthropometric features were directly measured, functional fitness was assessed with the Senior Fitness Test, and physical activity level was determined through the International Physical Activity Questionnaire; adherence to Mediterranean Diet (MD) was also collected through the MEDAS questionnaire. The SEM analysis revealed that functional fitness, which was a latent variable of the model described by the six administered fitness tests, was a strong predictor both of perceived physical and perceived mental health in the sample of elderly. Physical activity level was as predictor of the perceived physical component, but not of the mental health, while score of metabolic equivalent task did not result a predictor, as well as the sociodemographic factors and adherence to MD. The present findings suggest that it would be strongly recommended for elderly subjects to engage in physical activity specifically targeted to aged populations, in order to enhance their fitness abilities and enable them to improve the perception of their own health status.

Toward a New Conceptual Approach to "Intensity" in Soccer Player's Monitoring: A Narrative Review.

ABSTRACT: Pillitteri, G, Clemente, FM, Petrucci, M, Rossi, A, Bellafiore, M, Bianco, A, Palma, A, and Battaglia, G. Toward a new conceptual approach to "intensity" in soccer player's monitoring: A narrative review. J Strength Cond Res 37(9): 1896-1911, 2023-In the last decade, monitoring physiological and match-related demands in soccer has become an increasingly common practice in sports sciences. One of the great challenges during monitoring process is the identification of key indicators that permit to generalize evidence and sustain decision-making process during training prescription. Actually, one of the major debates in the scientific community and among practitioners is the identification of the "intensity" concept. Defining a given training session or exercise based on "intensity" is difficult due to the fact that a huge amount of indicators are available (related both to the performed activities and to the athletes' psychophysiological responses). These indicators can lead to specific outcomes with different interpretations. The current narrative review aims to discuss the different measures approaches used in soccer to describe the intensity for both internal and external demands. In addition, a second purpose of this review is to propose general recommendations for combining intensity indicators with the aim of defining an overall intensity score of a training session or drill.

Evaluation of Posturographic and Neuromuscular Parameters during Upright Stance and Hand Standing: A Pilot Study.

Upright bipedal posture is the physiological human posture; however, it is not the only possible form of human standing; indeed, an inverted position, a handstand, is required during gymnastics or other sports. Thus, this study aimed to understand the differences between the two standing strategies from a postural and neuromuscular perspective. Thirteen gymnasts with at least three years of sports experience underwent a baropodometric assessment and a surface electromyography (sEMG) examination in a standard upright bipodalic stance and during a handstand. The sEMG examination was performed on the gastrocnemius during an upright stance and on the flexor carpi radialis during the handstand. Limb weight distribution presented differences between the two vertical stances (p < 0.01). During the handstand, the weight ratio was prevalently observed on the palm of the hand for both hands with a significant difference between the front and rear aspect of the hand compared to the standing tasks (p < 0.01). Normalized sEMG amplitude showed significant differences during bipedal standing and hand standing; however, over a 5 s period, the normalized median frequency (MDF) value was similar for the two tasks. Both standing tasks presented similar postural weight managing patterns when analysed on the frontal plane, but they were different on the sagittal plane. In addition, the neuromuscular patterns during a 5 s window differ in amplitude but not for the frequency domain.

External load profile during different sport-specific activities in semi-professional soccer players.

BACKGROUND: Global Positioning System (GPS) devices are widely used in soccer for monitoring external load (EL) indicators with the aim of maximizing sports performance.The aim of this study was to investigate the EL indicators differences in players of different playing positions (i.e., central backs, external strikers, fullbacks, midfielders, strikers, wide midfielder) between and within different sport-specific tasks and official matches. METHODS: 1932 observations from 28 semi-professional soccer players (age: 25 ± 6 years, height: 183 ± 6 cm, weight: 75.2 ± 7 kg) were collected through GPS devices (Qstarz BT-Q1000EX, 10 Hz) during the season 2019-2020. Participants were monitored during Official Match (OM), Friendly Matches (FM), Small Sided Games (SSG), and Match-Based Exercises (MBE). Metabolic (i.e., metabolic power, percentage of metabolic power > 35w, number of intense actions per minute, distance per minute, passive recovery time per minute) and neuromuscular indicators (i.e., percentage of intense accelerations, percentage of intense decelerations, change of direction per min > 30°) were recorded during each task. RESULTS: Statistically significant differences were detected in EL indicators between playing positions within each task and between tasks. In particular, results from the two-way ANOVA tests showed significant interaction, but with small effect size, in all the EL indicators between playing positions for each task and within tasks. Moreover, statistical differences, but with small effect size, between playing positions were detected in each task and for each EL indicator. Finally, the strongest statistical differences (with large effect size) were detected between tasks for each EL indicator. Details of the Tukey post-hoc analysis reporting the pairwise comparisons within and between tasks with playing positions are also provided. CONCLUSION: In semi-professional soccer players, different metabolic and neuromuscular performance were detected in different playing position between and within different tasks and official matches. Coaches should consider the different physical responses related to different physical tasks and playing position to design the most appropriate training program.

Match Load Physical Demands in U-19 Professional Soccer Players Assessed by a Wearable Inertial Sensor.

BACKGROUND: Wearable inertial sensors are poorly used in soccer to monitor external load (EL) indicators. However, these devices could be useful for improving sports performance and potentially reducing the risk of injury. The aim of this study was to investigate the EL indicators (i.e., cinematic, mechanical, and metabolic) differences between playing positions (i.e., central backs, external strikers, fullbacks, midfielders, and wide midfielder) during the first half time of four official matches (OMs). METHODS: 13 young professional soccer players (Under-19; age: 18.5 ± 0.4 years; height: 177 ± 6 cm; weight: 67 ± 4.8 kg) were monitored through a wearable inertial sensor (TalentPlayers TPDev, firmware version 1.3) during the season 2021-2022. Participants' EL indicators were recorded during the first half time of four OMs. RESULTS: significant differences were detected in all the EL indicators between playing positions except for two of them (i.e., distance traveled in the various metabolic power zones (<10 w) and the number of direction changes to the right >30° and with speed >2 m). Pairwise comparisons showed differences in EL indicators between playing positions. CONCLUSIONS: Young professional soccer players showed different loads and performances during OMs in relation to playing positions. Coaches should consider the different physical demands related to playing positions in order to design the most appropriate training program.

Does Stretching Training Influence Muscular Strength? A Systematic Review With Meta-Analysis and Meta-Regression.

ABSTRACT: Thomas, E, Ficarra, S, Nunes, JP, Paoli, A, Bellafiore, M, Palma, A, and Bianco, A. Does stretching training influence muscular strength? A systematic review with meta-analysis and meta-regression. J Strength Cond Res 37(5): 1145-1156, 2023-The aim of this study was to review articles that performed stretching training and evaluated the effects on muscular strength. Literature search was performed using 3 databases. Studies were included if they compared the effects on strength following stretching training vs. a nontraining control group or stretching training combined with resistance training (RT) vs. an RT-only group, after at least 4 weeks of intervention. The meta-analyses were performed using a random-effect model with Hedges' g effect size (ES). A total of 35 studies ( n = 1,179 subjects) were included in this review. The interventions lasted for a mean period of 8 weeks (range, 4-24 weeks), 3-4 days per week, applying approximately 4 sets of stretching of approximately 1-minute duration. The meta-analysis for the stretching vs. nontraining control group showed a significant small effect on improving dynamic (k = 14; ES = 0.33; p = 0.007) but not isometric strength (k = 8; ES = 0.10; p = 0.377), following static stretching programs (k = 17; ES = 0.28; p = 0.006). When stretching was added to RT interventions, the main analysis indicated no significant effect (k = 17; ES = -0.15; p = 0.136); however, moderator analysis indicated that performing stretching before RT sessions has a small but negative effect (k = 7; ES = -0.43; p = 0.014); the meta-regression revealed a significant negative association with study length (ß = -0.100; p = 0.004). Chronic static stretching programs increase dynamic muscular strength to a small magnitude. Performing stretching before RT and for a prolonged time (>8 weeks) can blunt the strength gains to a small-to-moderate magnitude. Performing stretching in sessions distant from RT sessions might be a strategy to not hinder strength development.

Comparison of external load indicators between official matches and sport-specific training in semi-professional soccer players: focus on intensity and strength.

BACKGROUND: The aim of this study was to investigate any differences in external load indicators (ELi) between official matches (OM) and sport-specific tasks in semi-professional soccer players. METHODS: Among 28 semi-professional soccer players, 1932 observations (age: 25±6 years, height: 183±6 cm, weight: 75.2±7 kg; FC Palermo, Palermo, Italy) were collected through GPS devices (Qstarz BT-Q1000EX, 10 Hz; Qstarz International Co., Ltd., Taipei, Taiwan) and the related software (LaGalaColli V: 8.6.4.3; Spinitalia Srl, Rome, Italy) during the season 2019-2020. Participants were monitored during OM, friendly matches (FM), small sided games (SSG), and match-based exercises (MBE), considering the percentage of intense accelerations (%int. acc.), percentage of intense decelerations (%int. dec.), and passive recovery time /min (PrT/m) as Eli. RESULTS: We detected the highest mean value for PrT/m in OM and the lowest in MBE and SSG (18.36±4.38 and 13.4±5.26 and 13.4±4.29 (s/min), respectively). The lowest mean values of %int. acc. and %int. dec. were found in OM and the highest in SSG (8.64±1.52 vs. 13.02±3.14 and 9.25±1.56 vs. 15.68±3.14, for %int. acc. and %int. dec., respectively). Significant differences between the four tasks for all the ELi considered (P<0.001). The post-hoc pairwise comparisons revealed significant differences for all the ELi between all tasks (P<0.001) except for the %int. acc. between MBE vs. FM (P=0.003). No significant difference was found in PrT/m between MBE vs. FM and SSG vs. FM. CONCLUSIONS: ELi are in accordance with the performance model by achieving better values in training than OM, suggesting the fundamental role of GPS for monitoring external load in soccer.

Effects of sports experience on children's gross motor coordination level.

Background: Gross motor coordination (GMC) development could be influenced by age, gender, weight status, geographical area, living setting, home environment, socio-economic status, sports practice. Purpose: To verify whether practicing sports and practicing different sports could influence children's GMC level. Methods: A total of 295 children aged 8-11 years were involved in the study and divided into 5 groups in relation to the sport they practiced: gymnastics group (n = 67; 51F, 16M), cycling group (n = 64; 15F, 49M), athletics group (n = 47; 22F, 25M), swimming group (n = 35; 20F, 15M), control group (n = 82; 42F, 40M). The four subtests of the Körperkoordinations Test für Kinder (KTK) assessed children's GMC level. The scores from each of the four subtests were summed into the KTK total raw score (RS) and then converted into a gender- and age-specific motor quotient (MQ). Results: Children practicing sports showed significantly higher RS and MQ score than children of control group (203.14 ± 38.55 vs. 163.63 ± 43.50 and 98.56 ± 15.79 vs. 83.01 ± 16.71, respectively; p < 0.001). Children practicing gymnastics had a significantly higher RS and MQ than children of cycling, swimming, and control groups (p < 0.05), children of control group had a significantly lower RS and MQ than children of all other groups (p < 0.05). Children practicing gymnastics performed better walking backwards subtest than all other children's groups (p < 0.001). Children of control group performed worse jumping sideways subtest than children of gymnastics, athletics and swimming groups (p < 0.01). Children practicing gymnastics performed better moving sideways subtest than children of athletics, cycling and control groups (p < 0.01); children of control group performed worse than children of all other groups (p < 0.01). Children of control group performed worse hopping for height subtest than children of gymnastics, athletics and cycling groups (p < 0.05); children practicing gymnastics performed better than children of swimming and control groups (p < 0.05). Conclusions: The performance model and therefore the specialized training that each sport discipline required, could justified the differences in children's GMC level among sports groups. Thus, coaches should plan individualized interventions and choose activity contents to support children's GMC development.

Positional transversal release is effective as stretching on range of movement, performance and balance: a cross-over study.

BACKGROUND: The aim of this study was to compare the positional transversal release (PTR) technique to stretching and evaluate the acute effects on range of movement (ROM), performance and balance. METHODS: Thirty-two healthy individuals (25.3 ± 5.6 years; 68.8 ± 12.5 kg; 172.0 ± 8.8 cm) were tested on four occasions 1 week apart. ROM through a passive straight leg raise, jumping performance through a standing long jump (SLJ) and balance through the Y-balance test were measured. Each measure was assessed before (T0), immediately after (T1) and after 15 min (T2) of the provided intervention. On the first occasion, no intervention was administered (CG). The intervention order was randomized across participants and comprised static stretching (SS), proprioceptive neuromuscular facilitation (PNF) and the PTR technique. A repeated measure analysis of variance was used for comparisons. RESULTS: No differences across the T0 of the four testing sessions were observed. No differences between T0, T1 and T2 were present for the CG session. A significant time × group interaction for ROM in both legs from T0 to T1 (mean increase of 5.4° and 4.9° for right and left leg, respectively) was observed for SS, PNF and the PTR. No differences for all groups were present between T1 and T2. No differences in the SLJ and in measures of balance were observed across interventions. CONCLUSIONS: The PTR is equally effective as SS and PNF in acutely increasing ROM of the lower limbs. However, the PTR results less time-consuming than SS and PNF. Performance and balance were unaffected by all the proposed interventions.

How Does the Amount of a Physical Education Intervention Affect Gross Motor Coordination in Early Childhood?

Little is known about the dose-response of physical education interventions on motor coordination in preschoolers. Our aim was to investigate whether the development of motor skills changed depending on different amounts of a physical education program (PEP) in children aged 3-5 years. One hundred forty-five children were recruited from kindergartens and randomly divided into a control group (CG, n = 28), which did not perform any PEP, and two intervention groups, which performed 4 h/week (I1, n = 78) and 10 h/week (I2, n = 39) of a PEP for 16 weeks. Each lesson was set in the form of a programmed game in order to produce fun, thus increasing enthusiasm for participation. Before and after the intervention, locomotor and object control skills and the gross motor development quotient were assessed with the Italian version of the gross motor development test. Both intervention groups showed a significant increase in the motor skills compared with the control group. Moreover, the level of performance was significantly higher after 10 h/week compared to 4 h/week. These findings can be useful for standardizing PEPs in preschool settings so that they can be applied by teachers for planning effective programs for developing motor skills in early childhood.

Effects of Mediterranean Diet Combined with CrossFit Training on Trained Adults' Performance and Body Composition.

CrossFit is a high-intensity training discipline increasingly practiced in recent years. Specific nutritional approaches are usually recommended to maximize performance and improve body composition in high-intensity training regimens; notwithstanding, to date there are no targeted nutritional recommendations for CrossFit athletes. The Mediterranean Diet (MD) is a diet approach with a well-designed proportion of macronutrients, using only available/seasonal food of the Mediterranean area, whose health benefits are well demonstrated. No studies have evaluated this dietary strategy among CrossFit athletes and practitioners; for this reason, we tested the effects of 8 weeks of MD on CrossFit athletes' performance and body composition. Participants were assigned to two groups: a diet group (DG) in which participants performed CrossFit training plus MD, and a control group (CG) in which participants partook in the CrossFit training, continuing their habitual diet. Participants were tested before and after the 8 weeks of intervention. At the end of the study, no significant difference was noted in participants' body composition, whereas improvements in anaerobic power, explosive strength of the lower limbs, and CrossFit-specific performance were observed only in the DG. Our results suggest that adopting a MD in CrossFit athletes/practitioners could be a useful strategy to improve specific strength, endurance, and anaerobic capacity while maintaining overall body composition.

The effect of time-of-day and sleep deprivation on postural control: A systematic review.

BACKGROUND: Postural control (PC) can be affected by circadian rhythm and sleep deprivation, whereby it has been reported the result of PC measurement in clinical and experimental situations can be influenced by both factors. It has been suggested sleepiness can result in deficiency in PC, which in turn can lead to occupational accidents and subsequent injuries. This is while no study critically reviews or summarizes findings surrounding this topic in the literature. RESEARCH QUESTION: Is there any significant effect of sleep deprivation and circadian rhythm on PC variables among healthy individuals? METHODS: PubMed, Web of Science, Scopus, and Embase were used to detect relevant studies. Only studies that examined the effect of time of day and/or sleep loss on PC among healthy individuals were included in this systematic review. RESULTS: Forty-nine studies were included based on the inclusion criteria. Both circadian rhythm and sleep loss had a significant effect on PC, whereas there are inconsistent findings for optimal postural control regarding time of day. In terms of sleep deprivation, all investigations indicated that sleep loss deteriorates PC. SIGNIFICANCE: The current systematic review represents a significant effect of circadian rhythm and sleep deprivation on PC, whereby it is suggested that clinicians and researchers consider these factors when measuring PC since it may affect the result of research and clinical test. Moreover, PC may be worsened through sleeplessness; however, some studies revealed there is no linear relationship between time of wakefulness and deteriorating PC due to the influence of circadian rhythm. Hence, while PC, as an objective tool, can help to detect those who are sleep deprived, which in turn can lead to prevent possible musculoskeletal injuries, further studies are needed to reveal more understanding about the effect of sleep loss and circadian rhythm on PC.

Can the 20 and 60 s All-Out Test Predict the 2000 m Indoor Rowing Performance in Athletes?

Purpose: The purpose of this study was to look for a new, simple, and fast method of assessing and monitoring indoor race performance and to assess the relationship between 20 s, 60 s, and 2000 m indoor rowing performances of youth rowers to evaluate their anaerobic profile. Methods: For three consecutive days, 17 young able-bodied male rowers (15.8 ± 2.0 years), performed three tests (20 s, 60 s, and 2000 m) on a rowing ergometer. Mean power (W20, W60, and W2000) and 2000 m time (t2000) were considered for the analysis. In addition, 14 athletes (15-18 years) performed a 20 s, 60 s, and 2000 m tests and used this as a control group. To define the anaerobic profile of the athletes, W20 and W60 were normalized as percentages of W2000. Associations between variables were determined by means of the Pearson correlation coefficient (r). Results: Mean power decreased with increasing test duration (W20 = 525.1 ± 113.7 W; W60 = 476.1 ± 91.0 W; W2000=312.9 ± 56.0 W) and negative correlations emerged between t2000 (418.5 ± 23.1 s) and W20 (r = -0.952, p < 0.0001) and W60 (r = -0.930, p < 0.0001). Conclusion: These findings indicate that W20 and W60 are significant predictors of 2000 m rowing ergometer performances. Furthermore, normalized W20 and W60 can be used to evaluate athletes and as a reference for planning anaerobic training sessions, on a rowing ergometer.

Effects of Different Long-Term Exercise Modalities on Tissue Stiffness.

Stiffness is a fundamental property of living tissues, which may be modified by pathologies or traumatic events but also by nutritional, pharmacological and exercise interventions. This review aimed to understand if specific forms of exercise are able to determine specific forms of tissue stiffness adaptations. A literature search was performed on PubMed, Scopus and Web of Science databases to identify manuscripts addressing adaptations of tissue stiffness as a consequence of long-term exercise. Muscular, connective, peripheral nerve and arterial stiffness were considered for the purpose of this review. Resistance training, aerobic training, plyometric training and stretching were retrieved as exercise modalities responsible for tissue stiffness adaptations. Differences were observed related to each specific modality. When exercise was applied to pathological cohorts (i.e. tendinopathy or hypertension), stiffness changed towards a physiological condition. Exercise interventions are able to determine tissue stiffness adaptations. These should be considered for specific exercise prescriptions. Future studies should concentrate on identifying the effects of exercise on the stiffness of specific tissues in a broader spectrum of pathological populations, in which a tendency for increased stiffness is observed.