Post-activation performance enhancement does not occur following a large hand-paddles and parachute-resisted warm-up routine in collegiate swimmers.

Our aim was to investigate if using a warm-up routine that included parachute-resisted sprints with large hand-paddles improves 50 m freestyle performance in trained collegiate swimmers. Twelve swimmers (23.9 ± 2.2 years, 179 ± 7 cm, 77.1 ± 10.6 kg) participated in the study and completed two 50-m freestyle races, each preceded by a different warm-up routine, either control (CON) or experimental (EXP). The warm-up routines consisted of 500 m of swimming at self-selected speed, followed by four 10 s sprints with 1 min rest intervals. During EXP, sprints were performed using large hand-paddles and a swimming parachute, while during CON, sprints were performed freely. Performance and technique were assessed during the 50 m freestyle races. We found no significant differences in 25- and 50 m performance times (CON: 12.6 ± 0.8 vs. EXP: 12.5 ± 0.8 s, ES = 0.125; and CON: 26.8 ± 1.6 vs. EXP: 26.7 ± 1.7 s, ES = 0.06, respectively) between the two conditions. Mean stroke length (CON: 2.04 ± 0.21 vs. EXP: 2.02 ± 0.22 m·cycle-1, ES = 0.09), stroke frequency (CON: 55.4 ± 5.3 vs. EXP: 56.3 ± 5.2 cycles s-1, ES = 0.17), and propulsive time (CON: 0.62 ± 0.07 vs. EXP: 0.61 ± 0.06 s, ES = 0.15) were also not different between conditions. It is possible that the CON warm-up routine induced the priming effects that lead to PAPE, or that the EXP warm-up routine primed the athletes further but also induced greater fatigue, resulting in no significant effects on swimming performance. Our findings suggest that parachute-resisted sprints with hand-paddles during warm-up do not enhance 50 m freestyle swimming performance in trained collegiate swimmers. Coaches and practitioners should consider exploring different warm-up protocols to identify what works best for their athletes.

Chronic Adaptations to Eccentric Cycling Training: A Systematic Review and Meta-Analysis.

This study aimed to investigate the effects of eccentric cycling (ECCCYC) training on performance, physiological, and morphological parameters in comparison to concentric cycling (CONCYC) training. Searches were conducted using PubMed, Embase, and ScienceDirect. Studies comparing the effect of ECCCYC and CONCYC training regimens on performance, physiological, and/or morphological parameters were included. Bayesian multilevel meta-analysis models were used to estimate the population's mean difference between chronic responses from ECCCYC and CONCYC training protocols. Group levels and meta-regression were used to evaluate the specific effects of subjects and study characteristics. Fourteen studies were included in this review. The meta-analyses showed that ECCCYC training was more effective in increasing knee extensor strength, vastus lateralis fiber cross-sectional area, and six-minute walking distance compared to CONCYC. Moreover, ECCCYC was as effective as CONCYC in decreasing body fat percentage. CONCYC was more effective in increasing V˙O2max and peak power output attained during concentric incremental tests. However, group-level analyses revealed that ECCCYC was more effective than CONCYC in improving V˙O2max in patients with cardiopulmonary diseases. ECCCYC is a viable modality for exercise interventions aiming to improve parameters of muscle strength, hypertrophy, functional capacity, aerobic power, and body composition, with more advantages than CONCYC training in improving neuromuscular variables.

The Impact of ACTN3 Gene Polymorphisms on Susceptibility to Exercise-Induced Muscle Damage and Changes in Running Economy Following Downhill Running.

This study aimed to investigate if ACTN3 gene polymorphism impacts the susceptibility to exercise-induced muscle damage (EIMD) and changes in running economy (RE) following downhill running. Thirty-five healthy men were allocated to the two groups based on their ACTN3 gene variants: RR and X allele carriers. Neuromuscular function [knee extensor isometric peak torque (IPT), rate of torque development (RTD), and countermovement, and squat jump height], indirect markers of EIMD [muscle soreness, mid-thigh circumference, knee joint range of motion, and serum creatine kinase (CK) activity], and RE (oxygen uptake, minute ventilation, blood lactate concentration, and perceived exertion) for 5-min of running at a speed equivalent to 80% of individual maximal oxygen uptake speed were assessed before, immediately after, and 1-4 days after a 30-min downhill run (-15%). Neuromuscular function was compromised (P < 0.05) following downhill running with no differences between the groups, except for IPT, which was more affected in the RR individuals compared with the X allele carriers immediately (-24.9 ± 6.9% vs. -16.3 ± 6.5%, respectively) and 4 days (-16.6 ± 14.9% vs. -4.2 ± 9.5%, respectively) post-downhill running. EIMD manifested similarly for both the groups except for serum CK activity, which was greater for RR (398 ± 120 and 452 ± 126 U L-1 at 2 and 4 days following downhill running, respectively) compared with the X allele carriers (273 ± 121 and 352 ± 114 U L-1 at the same time points). RE was compromised following downhill running (16.7 ± 8.3% and 11 ± 7.5% increases in oxygen uptake immediately following downhill running for the RR and X allele carriers, respectively) with no difference between the groups. We conclude that although RR individuals appear to be more susceptible to EIMD following downhill running, this does not extend to the changes in RE.

Moving forward with backward pedaling: a review on eccentric cycling.

PURPOSE: There is a profound gap in the understanding of the eccentric cycling intensity continuum, which prevents accurate exercise prescription based on desired physiological responses. This may underestimate the applicability of eccentric cycling for different training purposes. Thus, we aimed to summarize recent research findings and screen for possible new approaches in the prescription and investigation of eccentric cycling. METHOD: A search for the most relevant and state-of-the-art literature on eccentric cycling was conducted on the PubMed database. Literature from reference lists was also included when relevant. RESULTS: Transversal studies present comparisons between physiological responses to eccentric and concentric cycling, performed at the same absolute power output or metabolic load. Longitudinal studies evaluate responses to eccentric cycling training by comparing them with concentric cycling and resistance training outcomes. Only one study investigated maximal eccentric cycling capacity and there are no investigations on physiological thresholds and/or exercise intensity domains during eccentric cycling. No study investigated different protocols of eccentric cycling training and the chronic effects of different load configurations. CONCLUSION: Describing physiological responses to eccentric cycling based on its maximal exercise capacity may be a better way to understand it. The available evidence indicates that clinical populations may benefit from improvements in aerobic power/capacity, exercise tolerance, strength and muscle mass, while healthy and trained individuals may require different eccentric cycling training approaches to benefit from similar improvements. There is limited evidence regarding the mechanisms of acute physiological and chronic adaptive responses to eccentric cycling.

The influence of the ACTN3 R577X polymorphism in the responsiveness to post-activation jump performance enhancement in untrained young men / A influência do polimorfismo R577X do gene ACTN3 na responsividade à melhora de desempenho de salto pós-ativação em indivíduos jovens destreinados

ABSTRACT We aimed to investigate the influence of alpha-actinin-3 (ACTN3) R577X polymorphism on responsiveness to post-activation performance enhancement (PAPE) of countermovement jumps (CMJ) in untrained subjects. Sixteen untrained men were allocated into two groups according to their ACTN3 gene alleles: homozygous for the X allele (XX, n = 9) or homozygous for the R allele (RR, n = 7). CMJ height, mean power output and vertical force were determined twice (CMJ1 and CMJ2) in two conditions: control (CON) and potentiated (PAPE). In the CON condition, CMJ were performed before and after a 15-min rest. In the PAPE condition, CMJ were performed 15 min before and 4 min following five squats with a 5-repetition maximum (5RM) load. Different conditions were applied on separate days in a randomized order. Statistical analysis involved three-way ANOVAs to compare the differences between conditions (CON and PAPE), time (CMJ1 and CMJ2), and groups (XX and RR). Significance level considered was p < 0.05. Effect sizes were calculated as Cohen's d. The effect sizes for changes in CMJ height for CON and following pre-activation for PAPE were 0.04 and 0.08, respectively. No significant differences were found for CMJ height between XX and RR at baseline (1.07 ± 2.54 cm e -0.82 ± 2.56 cm, respectively). No differences were found (p>0.05) in responsiveness to PAPE between the groups (XX = -0.20 ± 1.6 cm and RR = -0.81 ± 2.7 cm). We conclude that ACTN3 gene polymorphisms does not influence responsiveness to PAPE.

RESUMO Tivemos como objetivo investigar a influência do polimorfismo do gene ACTN3 na responsividade à potencialização do desempenho de salto com contra movimento (CMJ) pós-ativação (PAPE). Dezesseis homens destreinados foram divididos em dois grupos: homozigotos para os alelos X (XX, n = 9) ou R (RR, n = 7). A altura de CMJ, a potência média e a força vertical aplicada durante o salto pelos participantes foram determinadas duas vezes (CMJ1 e CMJ2) em duas condições: controle (CON) e potencializado (PAPE). Na condição CON, os CMJ foram realizados antes e depois de um período de 15 minutos de repouso. Na condição PAPE, os CMJ foram realizados 15 minutos antes e 4 minutos após a realização de cinco agachamentos com carga de cinco repetições máximas (5RM). As diferentes condições foram realizadas em dias separados e em ordem randomizada. ANOVAs fatoriais de três caminhos foram utilizadas para comparar diferenças entre condições, tempos e grupos. O tamanho do efeito foi calculado pelo d de Cohen. Os tamanhos do efeito para alterações na altura de CMJ para os grupos CON e PAPE foram 0.04 e 0.08, respectivamente. Não houve diferenças significantes entre os grupos XX e RR na altura de salto em condição basal (1.07 ± 2.54 cm e -0.82 ± 2.56 cm, respectivamente). Não houve diferenças significativas na responsividade à PAPE entre os grupos (XX = -0.20 ± 1.6 cm e RR = -0.81 ± 2.7 cm). O polimorfismo do gene ACTN3 parece não ser influenciar isoladamente a responsividade à PAPE.

A single bout of downhill running attenuates subsequent level running-induced fatigue.

Fatigue can be defined as exercise-induced strength loss. During running, fatigue can be partially explained by repetitive low-intensity eccentric contractions-induced muscle damage (EIMD). Previous studies showed that a bout of downhill running (DR) attenuated subsequent EIMD. Thus, we tested if a 30-min DR bout would attenuate fatigue induced by subsequent 60-min level running (LR). Twenty-seven male college students were randomly allocated to an experimental (EXP) or a control (CON) group. All participants performed LR on a treadmill at 70% of the velocity (vVO2peak) corresponding to peak oxygen uptake (VO2peak). Only EXP performed a 30-min DR (- 15%) on a treadmill at 70% vVO2peak fourteen days before LR. Indirect EIMD markers and neuromuscular function were assessed before, immediately and 48 h after DR and LR. Knee extension isometric peak torque (IPT) decreased (- 36.3 ± 26%, p < 0.05) immediately following DR with full recovery reached 48 h post-DR. Muscle soreness developed (p < 0.05) immediately (37 ± 25 mm) and 48 h (45 ± 26 mm) post-DR. IPT and rate of torque development (RTD) at late phases (> 150 ms) from the onset of muscle contraction decreased significantly (- 10.7 ± 6.1% and from - 15.4 to - 18.7%, respectively) immediately after LR for the CON group and remained below baseline values (- 5.6 ± 8.5% and from - 13.8 to - 14.9%, respectively) 48 h post-LR. However, IPT and late RTD were not significantly affected by LR for the EXP group, showing a group x time interaction effect. We concluded that a single DR bout can be used to attenuate fatigue induced by a LR performed fourteen days after.

Protective Effect Conferred by Isometric Preconditioning Against Slow- and Fast-Velocity Eccentric Exercise-Induced Muscle Damage.

We investigated if the same isometric preconditioning protocol (IPP) attenuates the magnitude of muscle damage induced by different maximal eccentric exercise protocols in the elbow flexors. Sixty-four untrained men were assigned to either two experimental or two control groups. Participants in the experimental groups performed an IPP prior to either slow (60°·s-1 - ISO + ECC-S) or fast (180°·s-1 - ISO + ECC-F) maximal eccentric contractions (MaxECC). Subjects in the control groups performed slow (ECC-S) or fast (ECC-F) MaxECC without IPP. Maximal isokinetic concentric torque (MVC), muscle soreness (SOR), and muscle thickness (MT) were assessed before, immediately after, and 1-4 days following the MaxECC. Significant (p < 0.05) group vs. time interactions were found for MVC (F = 4,517), SOR (F = 6,318), and MT (F = 1,863). The ECC-S group presented faster (p < 0.05) recovery of MVC and MT and less (p < 0.05) SOR at 96 h post-MaxECC compared with ECC-F group. No significant differences in MVC and MT were found between ECC-S and ECC-F groups following MaxECC. The ISO + ECC-S group showed faster (p < 0.05) recovery of MVC and SOR compared to the ECC-S group. No significant differences were evident between ISO + ECC-S and ECC-S in any variable. The ISO + ECC-F group showed faster (p < 0.05) recovery of all assessed variables compared with the ECC-F group. MVC was greater (p < 0.05) at 48-72 h, and SOR was less (p < 0.05) at 48-96 h in the ISO + ECC-F compared to the ECC-F group. No significant differences were evident between ISO + ECC-S and ISO + ECC-F for any variable. These results show that the IPP accelerated recovery of MVC and SOR for the slow-eccentric exercise condition and attenuated strength loss and SOR in addition to faster recovery of all assessed variables for the fast-eccentric exercise condition. Therefore, the IPP can be used as a strategy to attenuate and accelerate recovery of muscle damage induced by different-velocity eccentric exercises, resulting in greater protection against muscle damage induced by faster velocity.

Impact of Moderate Aerobic Training on Physical Capacities of Hypertensive Obese Elderly.

The association of old age and chronic conditions, such as hypertension and obesity, can lead to larger decreases in the physical capacities of elderly, compared with their healthy counterparts. Physical exercise has been demonstrated to be efficient in postponing this phenomenon, mainly strength training. However, little is known about the effect of aerobic training on this condition. The aim of this work was to investigate the impact of 12 weeks of moderate-intensity aerobic training on the physical capacities of hypertensive obese older women. Aerobic power, lower limb muscle power, upper limb muscle strength, endurance, and flexibility of 19 hypertensive obese elders were evaluated. Afterward, patients were blindly randomized into control group (CG) and exercise group (EG). EG underwent three sessions/week of 60 min of moderate-intensity aerobic training, during 12 weeks. EG showed increases in VO2max compared with CG (p = .03) and increases in flexibility compared with basal moment (+21.6%; p = .01) after 12 weeks, whereas CG did not show any significant alterations. Moderate aerobic training is capable of inducing increases in maximal aerobic power and flexibility in hypertensive obese elderly. However, other essential physical capacities associated with independence in elderly people (i.e., muscle power and strength) were not responsive to this kind of protocol.

Effects of resistance training on impulse above end-test torque and muscle fatigue.

NEW FINDINGS: What is the central question of this study? What role do neuromuscular fatigue mechanisms play in resistance training-induced adaptations of the impulse above end-test torque (IET) after the training period? What is the main finding and its importance? IET and global and peripheral fatigue were increased after a short period of resistance training. Thus, resistance training-induced adaptations in neuromuscular fatigue seem to contribute to enhanced IET after the training period. ABSTRACT: Short-term resistance training has a positive influence on the curvature constant of the power-duration relationship (W'). The physiological mechanism of W' enhancement after resistance training is unclear. This study aimed to determine whether one-leg maximal isometric resistance training influences (1) impulse above end-test torque (IET; an analogue of W') during a 5 min all-out isometric test; and (2) exercise tolerance (limit of tolerance, Tlim) and neuromuscular fatigue during severe exercise (i.e. above end-test torque; ET). Sixteen healthy active males participated in a 3-week unilateral knee extensor resistance-training programme, and 10 matched subjects participated as controls. The subjects were instructed to ramp up to 100% of maximal voluntary contraction (MVC) over 1 s, hold it for 3 s, and relax. Each repetition had a 2 s interval (10) and each set, a 2 min interval (3). MVC (18.6%) and muscle thickness (12.8%) were significantly improved after training. Significantly greater global (i.e. reduced MVC, 43.2 ± 13.5% vs. 58.9 ± 6.9%) and peripheral (51.7 ± 13.6% vs. 57.3 ± 15.3%) fatigue, IET (26%) and Tlim (92%) were obtained after resistance training. Moreover, both global (r = 0.57, P < 0.05) and peripheral fatigue (r = 0.55, P < 0.05) accrued during severe exercise were associated with IET. However, echo intensity, which reflects muscle quality, ET and central fatigue remained unchanged throughout the training period. No significant changes in the control group for any variable were observed. Resistance training-induced adaptations in muscle size and neuromuscular fatigue seem to contribute to enhanced IET and Tlim after the training period.

Explosive Training and Heavy Weight Training are Effective for Improving Running Economy in Endurance Athletes: A Systematic Review and Meta-Analysis.

BACKGROUND: Several strategies have been used to improve running economy (RE). Defined as the oxygen uptake required at a given submaximal running velocity, it has been considered a key aerobic parameter related to endurance running performance. In this context, concurrent strength and endurance training has been considered an effective method, although conclusions on the optimal concurrent training cannot yet be drawn. OBJECTIVE: To evaluate the effect of concurrent training on RE in endurance running athletes and identify the effects of subject characteristics and concurrent training variables on the magnitude of RE improvement. METHODS: We conducted a computerized search of the PubMed and Web of Science databases, and references of original studies were searched for further relevant studies. The analysis comprised 20 effects in 16 relevant studies published up to August 2015. The outcomes were calculated as the difference in percentage change between control and experimental groups (% change) and data were presented as mean ± 95 % confidence limit. Meta-analyses were performed using a random-effects model and, in addition, simple and multiple meta-regression analyses were used to identify effects of age, training status, number of sessions per week, training duration, type of strength training, and neuromuscular performance on % change in RE. RESULTS: The concurrent training program had a small beneficial effect on RE (% change = -3.93 ± 1.19 %; p < 0.001). In addition, explosive (% change = -4.83 ± 1.53; p < 0.001) and heavy weight (% change = -3.65 ± 2.74; p = 0.009) training programs produced similar improvements in RE, while isometric training (% change = -2.20 ± 4.37; p = 0.324) in selected studies did not induce a significant effect. The multiple linear meta-regression analysis showed that all the differences between % changes could be explained by including the above-mentioned characteristics of subjects and weight training program elements. This model showed that the magnitude of the % change in RE was larger for longer training duration (ß = -0.83 ± 0.72, p = 0.02). CONCLUSION: Explosive training and heavy weight training are effective concurrent training methods aiming to improve RE within a few weeks. However, long-term training programs seem to be necessary when the largest possible improvement in RE is desired.