Biological maturity vs. relative age: Independent impact on physical performance in male and female youth handball players.

Maturity status and relative age are two of the determining factors in talent development. The aim of the study was to analyze the influence of biological maturity status and relative age on physical performance in young male and female handball players. The sample included 48 males (14.11 ± 1.17 years) and 41 females (14.25 ± 1.64 years) players from one Spanish professional handball academy. Anthropometric data (height, sitting height, body mass and self-reported biological parent heights) and physical performance data (CMJ, DJ, 20 m speed, T-test and throwing velocity) were collected. Biological maturity status was determined as the percentage of predicted adult height, while relative age was estimated in birth quartiles based on biennial age grouping (Q1-Q8). The results showed a positive correlation between maturity status and CMJ in male players (p < 0.01). Differences in CMJ performance according to maturity status were identified (p < 0.05), with higher jump heights being recorded especially in early maturing boys (p < 0.01) and first lines and wings (p < 0.05). The variance in CMJ test scores could be explained by the maturity status by 42.90% in U-15 (p < 0.05) and 72.60% in U-16 male players (p < 0.001). By contrast, no differences were found in girls (p > 0.05). Moreover, no relationships were found between relative age and indices of physical performance (p > 0.05). Overall, maturity status had greater impacts on the tests of physical performance than relative age. Stakeholders should monitor the maturity status of young handball players to avoid physical performance biases that do not allow them to develop their sporting potential.

Effect of resistance exercise training on plasma neurofilaments in multiple sclerosis: a proof of concept for future designs.

Multiple sclerosis (MS) is a dysimmune and neurodegenerative disease of the central nervous system that continues to be one of the main causes of non-traumatic disability in young people despite the recent availability of highly effective drugs. Exercise-based interventions seem to have a positive impact on the course of the disease although pathophysiological mechanisms responsible for this benefit remain unclear. This is a longitudinal study to examine the effects of a short-term training program on neurofilament plasma levels, a biomarker of axonal destruction, measured using the ultrasensitive single molecule array (SiMoA). Eleven patients completed a 6-week supervised resistance-training program of 18 sessions that consisted of 3 sets of 8-10 repetitions of 7 exercises. Median plasma neurofilament levels significantly decreased from baseline (6.61 pg/ml) to 1 week after training intervention (4.44 pg/ml), and this effect was maintained after 4 weeks of detraining (4.38 pg/ml). These results suggest a neuroprotective effect of resistance training in this population and encourage us to investigate further the beneficial impact of physical exercise and to emphasize the importance of lifestyle in MS.

Validity and Reliability of Inertial Measurement System for Linear Movement Velocity in Flywheel Squat Exercise.

The aim of this study was to examine the validity and reliability of an Inertial Measurement System integrated into a secondary pulley (IMS) for determining linear velocity during flywheel squat exercises. Thirty-one male participants who were highly experienced in a flywheel resistance exercise training performed flywheel squat exercises with three incremental loads, and mean velocity (MV), mean propulsive velocity (MPV) and max velocity (Vmax) of the exercises were simultaneously recorded with a validated linear encoder and the IMS, in two different sessions. Validity was analyzed using ordinary least products regression (OLP), Lin's concordance correlation coefficient (CCC), and Hedge's g for the values from the linear encoder and the IMS. Test-retest reliability was determined by coefficient of variation (CV), Intraclass correlation coefficient (ICC), and standard error of measurement (SEM). Results showed a high degree of validity (OLP intercept = -0.09-0.00, OLP slope = 0.95-1.04, CCC = 0.96-0.99, Hedge's g < 0.192, SEM = 0.04-0.08) and reliability (CV < 0.21%, ICC > 0.88, SEM < 0.08). These results confirm that the IMS provides valid and reliable measures of movement velocity during flywheel squat exercises.

Cross-education effects of unilateral accentuated eccentric isoinertial resistance training on lean mass and function.

PURPOSE: We investigated the effects of three different unilateral isoinertial resistance training protocols with eccentric overload on changes in lean mass and muscle function of trained (TL) and contralateral non-trained (NTL) legs. METHODS: Physically active university students were randomly assigned to one of three training groups or a control group (n = 10/group). Participants in the training groups performed dominant leg isoinertial squat training twice a week for 6 weeks (4 sets of 7 repetitions) using either an electric-motor device with an eccentric phase velocity of 100% (EM100) or 150% (EM150) of concentric phase velocity or a conventional flywheel device (FW) with the same relative inertial load. Changes in thigh lean mass, unilateral leg-press one-repetition maximum (1-RM), muscle power at 40-80% 1-RM, and unilateral vertical jump height before and after training were compared between the groups and between TL and NTL. RESULTS: No changes in any variable were found for the control group. In TL, all training groups showed similar increases (p < 0.05) in 1-RM strength (22.4-30.2%), lean tissue mass (2.5-5.8%), muscle power (8.8-21.7%), and vertical jump height (9.1-32.9%). In NTL, 1-RM strength increased 22.0-27.8% without significant differences between groups; however, increases in lean mass (p < 0.001) were observed for EM150 (3.5%) and FW (3.8%) only. Unilateral vertical jump height (6.0-32.9%) and muscle power (6.8-17.5%) also increased in NTL without significant differences between training groups. CONCLUSION: The three eccentric-overload resistance training modalities produced similar neuromuscular changes in both the trained and non-trained legs, suggesting that strong cross-education effects were induced by the eccentric-overload training.

Ipsilateral Lower-to-Upper Limb Cross-Transfer Effect on Muscle Strength, Mechanical Power, and Lean Tissue Mass after Accentuated Eccentric Loading.

Background and Objectives: To investigate the effects of unilateral accentuated eccentric loading (AEL) on changes in lean mass and function of leg trained (TL) and ipsilateral non-trained arm (NTA) in young men and women. Materials and Methods: In a prospective trial, 69 Physically active university students (20.2 ± 2.2 years) were randomly placed into a training group (n = 46; 27 men, 19 women) or a control group without training (n = 23; 13 men, 10 women). Participants in the training group performed unilateral AEL in the leg press exercise of the dominant leg twice a week for 10 weeks. An electric motor device-generated isotonic resistance at different intensities for both concentric (30% of 1-RM) and eccentric contractions (105% of 1-RM). Changes in thigh and arm lean tissue mass, unilateral leg press and unilateral elbow flexion maximal concentric (1-RM) and isometric strength (MVIC), and unilateral muscle power at 40, 60, and 80% 1-RM for both leg press and elbow flexion exercises before and after intervention were compared between groups, between sexes and between TL and NTA. Results: Both men and women in the training group showed increases (p < 0.05) in lean tissue mass, 1-RM, MVIC, and muscle power for TL. In NTA, 1-RM, MVIC, and muscle power increased without significant differences between sexes, but neither in men nor women changes in lean tissue mass were observed. In addition, men showed greater changes in TL, but changes in NTA were similar between sexes. No gains in any variable were found for the control group. Conclusions: AEL protocol produced similar neuromuscular changes in TL and ipsilateral NTA, which suggests that strong ipsilateral lower-to-upper limb cross-transfer effects were induced by the eccentric-overload training. However, early ipsilateral increases in muscle force and power were not associated with lean mass gains. Both men and women experienced similar changes in NTA; however, men showed greater changes in TL.

Post-activation performance enhancement (PAPE) after a single bout of high-intensity flywheel resistance training.

This study investigated the post-activation performance enhancements (PAPE) induced by a high-intensity single set of accentuated eccentric isoinertial resistance exercise on vertical jump performance. Twenty physically active male university students performed, in randomized counterbalanced order, two different conditioning activities (CA) after a general preestablished warm-up: a conditioning set of 6 maximum repetitions at high intensity (i.e., individualized optimal moment of inertia [0.083 ± 0.03 kg·m-2]) of the flywheel half-squat exercise in the experimental condition, or a set of 6 maximal countermovement jumps (CMJ) instead of the flywheel exercise in the control condition. CMJ height, CMJ concentric peak power and CMJ concentric peak velocity were assessed at baseline (i.e., 3 minutes after the warm-up) and 4, 8, 12, 16 and 20 minutes after the CA in both experimental and control protocols. Only after the experimental protocol were significant gains in vertical jump performance (p < 0.05, ES range 0.10-1.34) at 4, 8, 12, 16 and 20 minutes after the CA observed. In fact, the experimental protocol showed greater (p < 0.05) CMJ height, concentric peak power and concentric peak velocity enhancements compared to the control condition. In conclusion, a single set of high-intensity flywheel training led to PAPE in CMJ performance after 4, 8, 12, 16 and 20 minutes in physically active young men.

The Relative Age Effect in the 10 Best Leagues of Male Professional Football of the Union of European Football Associations (UEFA).

The aim of the present research was to observe the relative age effect on professional soccer players of the ten best leagues of the Union of European Football Associations (UEFA), according to the IFFHS (International Federation of Football History and Statistics). The sample consisted of 5201 professional players who participated in the professional leagues during the 2016-2017 season. The birth date of each player was classified in four quartiles (Q1, Q2, Q3 and Q4). The frequencies (fr) and percentages (%) of the birth quartiles were analyzed. The chi square test (X2) and degrees of freedom (gl) were performed to check the differences in the intergroup distribution. Likewise, odd ratios were calculated for the different quartiles, where Q4 was the reference group according to the different leagues studied, playing positions (goalkeeper, defender, midfielder and forward) and classification (first four places, half-of the table and four last places). To calculate the size of the effect on the nominal variables, the Cramer V test was carried out. The results confirmed a greater representation of players born in Q1 and Q2, indicating statistically significant values (p < 0.05) for all the leagues studied, except in the Eerste Klasse A (Belgium). This significance was repeated for the demarcation variables in the field, with a greater effect in the case of the midfielders. Finally, the RAE also affected the three groups according to teams´ classification. The conclusions confirm the effect of the RAE in the sample studied, which would require a review of the talent selection processes in football in order to balance the chances of success of players born at the end of the year.

The Inclusion of Preplanned and Random and Unanticipated/Unexpected Events During Strength Training Improves the Ability to Repeat High-Intensity Efforts Under Uncertainty.

PURPOSE: To compare the effects of unilateral flywheel training (FT), using a rotational conical pulley, including multidirectional movements with either preplanned or random unanticipated/unexpected executions on functional performance in football players. METHODS: A total of 32 young male football players were randomly assigned to an FT program including preplanned unilateral multidirectional movements (PTG, n = 11), an FT executing the same unilateral movements through random (ie, right or left leg) unanticipated (ie, verbal or visual cue) or unexpected (ie, moment where the cue was provided) situations (UTG, n = 11), or a control group (n = 10) that followed their football training routine. FT consisted of 1 set × 5-12 repetitions of 4 exercises performed once a week for 10 weeks. Intermittent endurance performance, repeated unilateral and bilateral jumping ability, change-of-direction (COD) ability, linear sprint velocity, preplanned repeated-sprint ability (RSA), and uncertainty RSA (RSA-RANDOM) were assessed preintervention and postintervention. RESULTS: Significant improvements were found in RSA-RANDOM performance (P < .05, effect size [ES] range: UTG [1.83-2.16], PTG [0.69-0.73]) and COD (P < .05, ES: UTG = 1.34, PTG = 0.98]) in both training groups. Furthermore, significant improvements were also found in intermittent endurance performance (P = .016, ES = 0.37) and sprinting (P = .006, ES = 0.45) in UTG. No changes in any variable were found in the control group. No significant between-groups differences (P > .05) were reported between UTG and PTG, while differences were observed to the control group in unilateral jumping ability, COD, and RSA-RANDOM for UTG, and in RSA-RANDOM for PTG. CONCLUSIONS: A 10-week unilateral FT improved RSA-RANDOM and COD ability in youth football players, so both preplanned and unexpected situations should be included on strength training.

Pumping up the Fight against Multiple Sclerosis: The Effects of High-Intensity Resistance Training on Functional Capacity, Muscle Mass, and Axonal Damage.

BACKGROUND: Resistance training (RT) has been recognized as a beneficial non-pharmacological intervention for multiple sclerosis (MS) patients, but its impact on neurodegeneration is not fully understood. This study aimed to investigate the effects of high-intensity RT on muscle mass, strength, functional capacity, and axonal damage in MS patients. METHODS: Eleven relapsing-remitting MS patients volunteered in this within-subject counterbalanced intervention study. Serum neurofilament light-chain (NfL) concentration, vastus lateralis thickness (VL), timed up-and-go test (TUG), sit-to-stand test (60STS), and maximal voluntary isometric contraction (MVIC) were measured before and after intervention. Participants performed 18 sessions of high-intensity RT (70-80% 1-RM) over 6 weeks. RESULTS: Significant (p < 0.05) differences were observed post-intervention for VL (ES = 2.15), TUG (ES = 1.98), 60STS (ES = 1.70), MVIC (ES = 1.78), and NfL (ES = 1.43). Although moderate correlations between changes in VL (R = 0.434), TUG (R = -0.536), and MVIC (R = 0.477) and changes in NfL were observed, only the correlation between VL and MVIC changes was significant (R = 0.684, p = 0.029). CONCLUSIONS: A 6-week RT program significantly increased muscle mass, functional capacity, and neuromuscular function while also decreasing serum NfL in MS patients. These results suggest the effectiveness of RT as a non-pharmacological approach to mitigate neurodegeneration while improving functional capacity in MS patients.

Winners do what they fear: exercise and peripheral arterial disease-an umbrella review.

AIMS: This systematic review aims to evaluate and summarize findings from published meta-analyses on the effects of regular exercise in patients with peripheral arterial disease (PAD). The review will assess the impact of exercise on functional parameters, health-related quality of life, haemodynamic parameters, physical activity levels, adverse events, and mortality. METHODS AND RESULTS: A systematic search was performed in PubMed, Web of Science, Scopus, and Cochrane Library databases (up to May 2023) to identify meta-analyses including randomized controlled trials that examined the effects of regular exercise in patients with PAD. Sixteen studies, with a total of 198 meta-analyses, were identified. Results revealed with strong evidence that patients with PAD who exercised improved functional and health-related quality of life parameters. Specifically, supervised aerobic exercise (i.e. walking to moderate-maximum claudication pain) improves maximum walking distance [mean difference (MD): 177.94 m, 95% confidence interval (CI) 142.29-213.60; P < 0.00001; I2: 65%], pain-free walking distance (fixed MD: 68.78 m, 95% CI 54.35-83.21; P < 0.00001; I2: 67%), self-reported walking ability [i.e. distance score (MD: 9.22 points, 95% CI 5.74-12.70; P < 0.00001; I2: 0%), speed score (MD: 8.71 points, 95% CI 5.64-11.77; P < 0.00001, I2: 0%), stair-climbing score (MD: 8.02 points, 95% CI 4.84-11.21; P < 0.00001, I2: 0%), and combined score (MD: 8.76 points, 95% CI 2.78-14.74; P < 0.0001, I2: 0%)], aerobic capacity (fixed MD: 0.62 mL/kg/min, 95% CI 0.47-0.77, P < 0.00001, I2: 64%), and pain score (MD: 7.65, 95% CI 3.15-12.15; P = 0.0009; I2: 0%), while resistance exercise improves lower limb strength (standardized mean difference: 0.71, 95% CI 0.29-1.13, P = 0.0009; I2: 0%]. Regarding other outcomes, such as haemodynamic parameters, no significant evidence was found, while physical activity levels, adverse events, and mortality require further investigation. CONCLUSION: Synthesis of the currently available meta-analyses suggests that regular exercise may be beneficial for a broad range of functional tasks improving health-related quality of life in patients with PAD. Supervised aerobic exercise is the best type of exercise to improve walking-related outcomes and pain, while resistance exercise is more effective to improve lower limb strength.

Regular exercise is beneficial for a wide range of functional capacity-related outcomes that seem to improve health-related quality of life in patients with peripheral arterial disease (PAD). Supervised aerobic exercise (i.e. walking to moderate­maximum claudication pain) is the best type of exercise to improve walking-related outcomes and pain. Resistance exercise improves lower limb strength.

Force Production and Electromyographic Activity during Different Flywheel Deadlift Exercises.

This study aimed to characterize and compare force production and muscle activity during four flywheel deadlift exercises (bilateral [Bi] vs. unilateral [Uni]) with different loading conditions (vertical [Ver] vs. horizontal [Hor]). Twenty-three team-sport athletes underwent assessments for exercise kinetics (hand-grip force), along with surface electromyography (sEMG) of the proximal (BFProx) and medial biceps femoris (BFMed), semitendinosus (ST), and gluteus medius (GM). Mean and peak force were highest (p < 0.001) in Bi + Ver compared with Bi + Hor, Uni + Ver, and Uni + Hor. Although no significant differences were observed between Bi + Hor and Uni + Ver, both variants showed higher (p < 0.001) average force and peak eccentric force when compared with Uni + Hor. The presence of eccentric overload was only observed in the vertically loaded variants. Bi + Ver and Uni + Ver showed higher (p < 0.05) sEMG levels in BFProx and BFMed compared with the Uni + Hor variant. In addition, Uni + Ver registered the largest GM and ST sEMG values. In conclusion, the vertical variants of the flywheel deadlift exercise led to higher muscle force production and sEMG compared with their horizontal counterparts. Both Bi + Ver and Uni + Ver may be effective in promoting an increase in hamstring muscles activity and muscle force at long muscle length, while the Uni + Ver variant may be more effective in promoting GM and ST involvement.

Current Guidelines for the Implementation of Flywheel Resistance Training Technology in Sports: A Consensus Statement.

BACKGROUND: Flywheel resistance training has become more integrated within resistance training programs in a variety of sports due to the neuromuscular, strength, and task-specific enhancements reported with this training. OBJECTIVE: This paper aimed to present the consensus reached by internationally recognized experts during a meeting on current definitions and guidelines for the implementation of flywheel resistance training technology in sports. METHODS: Nineteen experts from different countries took part in the consensus process; 16 of them were present at the consensus meeting (18 May 2023) while three submitted their recommendations by e-mail. Prior to the meeting, evidence summaries were developed relating to areas of priority. This paper discusses the available evidence and consensus process from which recommendations were made regarding the appropriate use of flywheel resistance training technology in sports. The process to gain consensus had five steps: (1) performing a systematic review of systematic reviews, (2) updating the most recent umbrella review published on this topic, (3) first round discussion among a sample of the research group included in this consensus statement, (4) selection of research group members-process of the consensus meeting and formulation of the recommendations, and (5) the consensus process. The systematic analysis of the literature was performed to select the most up-to-date review papers available on the topic, which resulted in nine articles; their methodological quality was assessed according to AMSTAR 2 (Assessing the Methodological Quality of Systematic Review 2) and GRADE (Grading Recommendations Assessment Development and Evaluation). Statements and recommendations scoring 7-9 were considered appropriate. RESULTS: The recommendations were based on the evidence summary and researchers' expertise; the consensus statement included three statements and seven recommendations for the use of flywheel resistance training technology. These statements and recommendations were anonymously voted on and qualitatively analyzed. The three statements reported a score ranging from 8.1 to 8.8, and therefore, all statements included in this consensus were considered appropriate. The recommendations (1-7) had a score ranging from 7.7 to 8.6, and therefore, all recommendations were considered appropriate. CONCLUSIONS: Because of the consensus achieved among the experts in this project, it is suggested that practitioners and researchers should adopt the guidelines reported in this consensus statement regarding the use of flywheel resistance technology in sports.

Effects of exchange vs. controlled diet on biochemical, body composition and functional parameters in elite female soccer players.

Due to the increasing level of professionalism, the high frequency of competitions, and the alarming injury rate observed in elite female soccer players, multidisciplinary strategies, including nutritional monitoring, need to be implemented. This study aimed to quantify energy, macronutrient and micronutrient intakes during the competitive period and to analyze the effects of two different nutritional interventions on nutritional knowledge, anthropometric data, biochemical values and physical performance. 19 elite female soccer players were randomly divided into two groups: the controlled-diet group (CG, n = 10), that followed a diet based on pre-established menus, and the exchange-diet group (EG, n = 9), that designed their own menus with an exchanged list. A cross-sectional study was designed to evaluate the dietary intake, while an experimental randomized controlled trial was designed to compare the effects of both 12-week nutritional interventions. Total energy, CHO, PROT, fibre and micronutrients intakes were below the general recommendations for athletes while, total and saturated fat intakes were above these. Moreover, there were no differences in diet during weekdays, pre-competition and competition days. The study also revealed a low nutritional knowledge and exchanged diet has demonstrated to be a better strategy to improve this. Biochemical monitoring showed that participants presented decreased concentration of haemoglobin and controlled diet may lead to greater effects on haemoglobin concentration and in anemia prevention. Both EG and CG showed significant reduction on skinfolds sum after intervention, but no significant differences were observed in thigh and calf indices. However, no significant changes were observed in soccer-related skills for any group.

Exercise interventions for patients with type 1 diabetes mellitus: A narrative review with practical recommendations.

Type 1 diabetes mellitus (T1DM) is a chronic endocrine disease that results from autoimmune destruction of pancreatic insulin-producing ß cells, which can lead to microvascular (e.g., retinopathy, neuropathy, and nephropathy) and macro-vascular complications (e.g., coronary arterial disease, peripheral artery disease, stroke, and heart failure) as a consequence of chronic hyperglycemia. Despite the widely available and compelling evidence that regular exercise is an efficient strategy to prevent cardiovascular disease and to improve functional capacity and psychological well-being in people with T1DM, over 60% of individuals with T1DM do not exercise regularly. It is, therefore, crucial to devise approaches to motivate patients with T1DM to exercise, to adhere to a training program, and to inform them of its specific characteristics (e.g., exercise mode, intensity, volume, and frequency). Moreover, given the metabolic alterations that occur during acute bouts of exercise in T1DM patients, exercise prescription in this population should be carefully analyzed to maximize its benefits and to reduce its potential risks.

Acute Effects of Blood Flow Restriction Training on Movement Velocity and Neuromuscular Signal during the Back Squat Exercise.

The aim of this study was to verify the effects of blood flow restriction on movement velocity and muscle activity during the back squat exercise. METHODS: Twenty-four university students participated in this study. In two randomized sessions 72 h apart, participants performed a 4-set protocol consisting of 30-15-15-15 repetitions performed at 30% of their one-repetition maximum in the back squat exercise. In both sessions, neuromuscular function was monitored by surface electromyography (EMG) and movement velocity (mean propulsive velocity (MPV), peak concentric velocity (Vmax), and the effort index (EI)). Blood flow restriction (BFR) was applied during exercise in one of the experimental sessions with 80% of full arterial occlusion pressure over lower limbs. RESULTS: The BFR condition showed higher (p < 0.05) EI, peak, and rooted mean square normalized EMG in Set 1 compared to Set 2. Similar MPV and Vmax were observed in each set for both the BFR and control conditions. No significant differences were observed between conditions in any set. CONCLUSIONS: BFR did not imply changes in neuromuscular performance during low-intensity resistance training, but it might induce greater intra-series velocity loss and less excitation of the muscles involved.

Effects of submaximal and supramaximal accentuated eccentric loading on mass and function.

Introduction: Eccentric-overload (EO) resistance training emerges as an alternative to more optimally prescribe intensity relative to the force generation capabilities of the eccentric muscle contraction. Given the difficulties to individually prescribe absolute eccentric loads relative to each person's eccentric ability, setting the load relative to the concentric one-repetition maximum (1-RM) is the most used EO training approach. Therefore, we investigated the effects of submaximal and supramaximal (i.e., eccentric loads above 100% of 1-RM) accentuated eccentric training on changes in lean mass, anabolic hormonal responses and muscle function. Methods: Physically active university students (n = 27) were randomly assigned to two training groups. Participants in the training groups performed dominant leg isotonic training twice a week for 10 weeks (four sets of eight repetitions). Isotonic resistance was generated by an electric-motor device at two different percentages of 1-RM for the eccentric phase; 90% submaximal load, SUB group) and 120% (supramaximal load, SUPRA group). Concentric load was the same for both groups (30% of 1-RM). Changes in total thigh lean mass (TTLM), anabolic hormonal responses (growth hormone, IGF-1, IL-6, and total testosterone), unilateral leg-press 1-RM, maximal voluntary isometric contractions (MVIC), local muscle endurance (XRM), muscle power at 40 (PP40), 60 (PP60) and 80% (PP80) of the 1-RM, and unilateral vertical jump height before and after training were compared between groups. Results: After training, both SUB and SUPRA groups showed similar increases (p < 0.05) in MVIC (19.2% and 19.6%), XRM (53.8% and 23.8%), PP40 (16.2% and 15.7%), TTLM (2.5% and 4.2%), IGF-1 (10.0% and 14.1%) and IL-6 (58.6% and 28.6%). However, increases in 1-RM strength (16.3%) and unilateral vertical jump height (10.0%-13.4%) were observed for SUPRA only. Indeed, SUPRA was shown to be more favorable than SUB training for increasing 1-RM [ES = 0.77 (1.49-0.05)]. Unilateral muscle power at medium and high intensity (10.2% and 10.5%) also increased in SUB but without significant differences between groups. Discussion: Similar functional and structural effects were demonstrated after 10 weeks EO training with submaximal and supramaximal eccentric loads. Although supramaximal loading might be superior for increasing 1-RM, the use of this approach does not appear to be necessary in healthy, active individuals.

Use of concentric linear velocity to monitor flywheel exercise load.

Purpose: To propose the concentric linear velocity measurement as a valid method to quantify load and individualise the prescription of flywheel training, we investigated the relationship between inertial load and mean concentric linear velocity (MCLV) during the flywheel squat exercise in a wide spectrum of intensities. In addition, we compared MCLV and subjective rating of perceived exertion (RPE) after each load. Methods: Twenty-five physically active men volunteered for this study (26.5 ± 2.9 years, 179.5 ± 4.2 cm, 81.6 ± 8.6 kg). After familiarization, all participants performed two inertial progressive load tests on separated days to determine the flywheel load-velocity profile and its reliability. Each participant performed 5 set of 6 repetitions of the flywheel squat exercise with different inertial loads (0.047, 0.104, 0.161, 0.245, 0.321 kg m2) selected in a counterbalanced and randomized order for each testing day. Average MCLV and RPE for each load were compared. Results: The inter-session intraclass correlation coefficient (ICC) showed values above 0.9 in all the included outcomes (MCLV: ICC = 0.91; RPE: ICC = 0.93). A significant correlation (p < 0.01, R 2 = 0.80) between inertial load and MCLV was found. Similarly, significant correlation models (p < 0.01) were observed between RPE and load (R 2 = 0.87) and (R 2 = 0.71) between RPE and MCLV. Conclusion: The control of MCLV during flywheel exercise can be proposed as a valid method to quantify load and to individualize the prescription of flywheel training. In addition, RPE responses have demonstrated significant correlations with load and velocity. Therefore, RPE has been proposed as a valid and reliable alternative to control flywheel training.

Effects of ankle position during the Nordic Hamstring exercise on range of motion, heel contact force and hamstring muscle activation.

One of the main benefits of the Nordic Hamstring Exercise (NHE) is that it can be performed without the need of any extra material. However, numerous technical execution variables such as the ankle and pelvis position can influence the performance. The primary aims of this study were to investigate the effects of ankle position (i.e., plantar or dorsal flexion) on Nordic Hamstring Break Point (NHBP), repetition time and heel contact force. A secondary aim was to investigate differences in biceps femoris long head and semitendinosus muscle activation. Male professional field hockey players (n = 12) volunteered for the study. Paired t-tests were used to analyse the effect of ankle position on muscle NHBP, eccentric peak torque and repetition time. Ankle dorsal flexion resulted in a higher NHBP (p = 0.002, effect size [ES] = 1.48 [0.57 to 2.38]), repetition time (p = 0.004, ES = 0.98 [0.24 to 1.72]) and both absolute and relative heel contact force (p = 0.028, ES = 0.67 [0.01 to 1.34], p = 0.017, ES = 0.76 [0.07 to 1.44], respectively) compared to plantar flexion. Muscle activation was not significant different. This study showed a higher NHBP, absolute and relative heel contact force and repetition time with a dorsal flexed ankle vs. a plantar flexed ankle in the NHE, without changes in hamstrings muscle activation.

Comparison of Flywheel and Pneumatic Training on Hypertrophy, Strength, and Power in Professional Handball Players.

Purpose: The mechanical properties of resistance-training machines are a variable that may help to optimize sports performance and injury prevention protocols. The purpose of this study was to examine two non-gravity-dependent training modalities on muscle structure and function. Methods: Eighteen professional handball players were randomly divided into two experimental groups: 1) iso-inertial flywheel training (FW) and 2) pneumatic resistance training (PN). Participants in both groups completed twelve training sessions in six weeks consisting of three movements (lateral raise, internal and external rotation). Four sets of seven repetitions for each movement were performed during each session. Before and after training subscapularis and deltoid (anterior, middle, posterior) muscle thickness was measured. Isokinetic torque and power during internal and external rotation at 60, 180, and 240 deg·s-1 was measured as well. Throwing speed was assessed before and after training while both sitting and standing situations. Results: Both groups showed similar significant increases in throwing speed and internal and external rotation peak torque, average and peak power at all angular velocities. Anterior and middle deltoid muscle thickness changes were greater after training in FW (20 and 22%) in comparison to PN (14 and 7%, respectively). Conclusions: In summary, both flywheel and pneumatic training resulted in similar increases in shoulder strength and power and throwing speed. However, flywheel training appeared to possibly result in a slightly greater level of muscle hypertrophy of the anterior and middle deltoid. Non-gravity dependent training appears to induce changes that would be beneficial to sports performance and perhaps injury prevention.

Effects of Preceding Transcranial Direct Current Stimulation on Movement Velocity and EMG Signal during the Back Squat Exercise.

This study aimed to evaluate the effects of preceding anodal transcranial direct stimulation (a-tDCS) over the dorsolateral prefrontal cortex (DLPFC) during the back squat exercise on movement velocity and surface electromyographic (sEMG) activity. Thirteen healthy, well-trained, male firefighters (34.72 ± 3.33 years; 178 ± 7.61 cm; 76.85 ± 11.21 kg; 26.8 ± 4.2 kg·m−2; back squat 1-repetition maximum 141.5 ± 16.3 kg) completed this randomised double-blinded sham-controlled crossover study. After familiarisation and basal measurements, participants attended the laboratory on two occasions separated by 72 h to receive either Sham or a-tDCS (current intensity of 2 mA for 20 min). Immediately after stimulation, participants completed three sets of 12 repetitions (70% of 1-RM) with three minutes of recovery between sets monitored with a linear position transducer. The sEMG of the rectus femoris (RF) and vastus lateralis (VL) of both legs were recorded. No significant differences were observed between a-tDCS and Sham interventions on mean concentric velocity at any set (p > 0.05). Velocity loss and effort index were significantly higher (p < 0.05) in set 3 compared to set 1 only in the a-tDCS group. The right-leg RM and right-leg VL elicited the greatest muscle activation during set 1 after a-tDCS and Sham, respectively (p < 0.05). Our results revealed that a-tDCS over the DLPFC might impact movement velocity or fatigue tolerance in well-trained individuals. Notwithstanding, significant differences in dominant-leg muscle activity were found both in a-tDCS and Sham.