Sprint kayaking performance enhancement by isometric strength training inclusion: a randomized controlled trial

Performing isometric strength training (IST) can enhance various sports performance. This study compared the effects of including IST on sprint kayaking performance as compared to traditional strength training. Twenty sprint kayaking athletes (age 22 +- 4 year, stature 1.71 +- 0.09 m, body mass 72.0 +- 11.4 kg) performed a 200-m kayak ergometer time trial (200mTT), isometric squat (IsoSqT), isometric bench press (IsoPress) and isometric prone bench pull (IsoPull) during the preand post-tests. Athletes were randomly assigned to either traditional strength training (TRAD) or IST group. Both groups performed a similar strength training program twice a week for six weeks. However, half the volume for squat, bench press and prone bench pull were replaced by IsoSqT, IsoPress and IsoPull, respectively, for the IST group. IsoSqT was performed at 90º knee angle, while IsoPress and IsoPull were performed at 90º and 120º elbow angles, respectively.info:eu-repo/semantics/publishedVersio

Syntheses, Raman Spectroscopy and Crystal Structures of Alkali Hexa-fluoridorhenates(IV) Revisited

The A2[ReF6] (A = K, Rb and Cs) salts are isotypic and crystallize in the trigonal space group type P\overline{3}m1, adopting the K2[GeF6] structure type. Common to all A2[ReF6] structures are slightly distorted octa­hedral [ReF6]2− anions with an average Re—F bond length of 1.951 (8) Å. In those salts, symmetry lowering on the local [ReF6]2− anions from Oh (free anion) to D3d (solid-state structure) occur. The distortions of the [ReF6]2− anions, as observed in their Raman spectra, are correlated to the size of the counter-cations

Effects of mental fatigue on maximal exercise test performance in physically active and sedentary adults

This study examined the effects of mental fatigue on maximal treadmill walking exercise performance. METHODS: 50 young male (n = 25) and female (n = 25) adults were recruited to perform a maximal treadmill walking exercise test to volitional exhaustion on two occasions. Prior to the exercise test, participants performed a cognitive task in a randomized, counterbalanced manner for 30 minutes, with the incongruent Stroop task in the mental fatigue condition, and leisure magazine reading in the control condition. Subjective ratings of perceived mood, fatigue, and motivation to exercise were assessed before and after the cognitive task. Perceptual and physiological responses were collected throughout the exercise test.info:eu-repo/semantics/publishedVersio

Effects of isometric strength and plyometric training on running performance: a randomized controlled study

The aim of the study was to compare the effects of isometric strength (IST) and plyometric training (PT) on endurance running performance. Methods: Twenty-six endurance runners (18 males and 8 females; age 36 +/- 6 years, stature 1.69 +/- 0.05 m body mass 61.6 +/- 8.0 kg, VO2max 50.4 +/- 5.8 ml center dot kg(-1)center dot min(-1)) completed the countermovement jump (CMJ), isometric mid-thigh pull (IMTP), 2.4 km run time trial (2.4kmTT), running economy test (RE) and a graded exercise test measures at baseline. They were then randomly assigned to three groups, the control (CON), PT or IST group, and completed the circuit, plyometric or isometric training, respectively, twice a week for 6 weeks, while still continuing to perform their planned running training. They then completed the same set of measures performed at baseline post-intervention. Results: Significant time x group interactions and time main effect were observed for 2.4kmTT (P = .002, n(p)(2) = .45 and P < .001, n( )(2)=0.72), maximal aerobic speed (MAS) (P = .006, n(p)(2) = .39), CMJ height (P < .001, n(p)(2) = .55) and IMTP relative peak force (P = .001, n(p)(2) = .50) in favor of PT and IST. Significant main effect for time was observed for 2.4kmTT (P < .001, n(p)(2) = .72), RE (P = .048, n(p)(2) = .17), VO2max (P = .047, n(p)(2) = .18), MAS (P < .001, n(p)(2) = .63), CMJ height (P < .001, n(p)(2) = .51) and IMTP relative peak force (P < .001, n(p)(2) = .58). Conclusion: In conclusion, both PT and IST were similarly effective at enhancing running endurance performance. However, IST resulted in greater improvement to RE.The author(s) reported there is no funding associated with the work featured in this article.info:eu-repo/semantics/publishedVersio

Effects of two isometric strength training methods on jump and sprint performances: a randomized controlled trial

Isometric strength training (IST) with rapid non-sustained contraction (RIST) is effective in improving the ability to generate force rapidly. However, the neuromuscular adaptation of IST with sustained contraction (SIST) and RIST is not known. Therefore, the aim of the study was to compare the neuromuscular adaptations of RIST with SIST. Methods Thirty-three national floorball players (23.9 ± 3.1 years old; 1.69 ± 0.08 m; 64.6 ± 11.1 kg) were recruited for this study. Pre- and post-test included countermovement jump (CMJ), 30-m sprint (TT30), isometric squat at 90° (ISqT90) and 120° (ISqT120) knee angles. They were randomly assigned to either control (Con) (n = 9), RIST (n = 12) or SIST (n = 12) group and performed 12 sessions of intervention training. All groups performed the same sets of exercises, but RIST and SIST had to perform ISqT with and without sustained contraction, respectively. Results Time × group effect for CMJ height (P = 0.01, ƞp 2 = 0.25), peak force (PF) (P = 0.03, ƞp 2 = 0.22) and rate of force development (RFD) (P = 0.02, ƞp 2 = 0.22) obtained from ISqT120 were noted. A main effect for time was observed in CMJ height, PF obtained from ISqT90 and ISqT120, and RFD obtained from ISqT90 (P < 0.01, 0.27 < ƞp 2 < 0.57). There was greater improvement in TT30 (P = 0.043, d = 3.00), ISqT90 PF (P = 0.034, d = 3.12), ISqT120 PF (P = 0.003, d = 4.54) and ISqT120 RFD (P = 0.033, d = 1.36) in the SIST than the Con group. Conclusion SIST was more effective in improving strength and dynamic performance as compared to RIST, making it a viable training method to enhance dynamic performances.info:eu-repo/semantics/publishedVersio

Physiological adaptations to training in competitive swimming: a systematic review.

The purpose of this systematic review was to summarize longitudinal evidences on swimming physiology and draws implications for daily practice. A computerized search of databases according to the PRISMA statement was employed. Studies were screened for eligibility on inclusion criteria: (i) present two testing points; (ii) on swimming physiology; (iii) using adult elite swimmers; (iv) not case-studies or with small sample sizes. Two independent reviewers used a checklist to assess the methodological quality of the studies. 34 studies were selected for analysis. Studies were gathered into five main categories: blood composition (n=7), endocrine secretion (n=11) muscle biochemistry (n=7), cardiovascular response (n=8) and energetic profile (n=14). The mean quality index was 10.58 ± 2.19 points demonstrating an almost perfect agreement between reviewers (K = 0.93). It can be concluded that the mixed findings in the literature are due to the diversity of the experimental designs. Micro variables obtained at cellular or molecular level are sensitive measures that suggest overtraining signs and health symptoms. The improvement of macro variables (i.e. main physiological systems) is limited and may depend on the athletes’ training background and experience

Arm-pull thrust in human swimming and the effect of post-activation potentiation

The aim of this study was to analyse the front-crawl arm-pull kinetics and kinematics, comparing it before and after post-activation potentiation (PAP), and the associations between variables describing of the arm-pull kinetics. Twelve male competitive swimmers were randomly assigned to perform two different warm-ups in a crossover manner: (i) non-PAP (control condition); and (ii) PAP (experimental condition). PAP consisted of 2 × 5 arm-pulls with resistance bands by both upper-limbs. Eight minutes later, participants underwent a 25 m all-out trial in front-crawl arm-pull. Kinetics (i.e., peak thrust, mean thrust and thrust-time integral) and kinematics (i.e., speed and speed fluctuation) were collected by an in-house customised system composed of differential pressure sensors, speedo-meter and underwater camera. There was a significant and large improvement of the arm-pull kinetics after completing the warm-up with PAP sets (0.010 < P < 0.054, 0.50 < d < 0.74). There were non-significant and small effects of PAP on speed (P = 0.307, d = 0.18) and speed fluctuation (P = 0.498, d = 0.04). Correlation coefficients among kinetic variables were significant with large associations (0.51 < R < 0.90, 0.001 < P < 0.088). In conclusion, warm-ups including PAP conditioning sets elicit a large improvement in the thrust, but with small improvement in performance.This research was funded by NIE AcRF Grant (RI 6/17 TB), Portuguese Foundation for Science and Technology (UID04045/2020), and European Fund for Regional Development (FEDER)-COMPETE 2020 (POCI-01-0145-FEDER-006969).info:eu-repo/semantics/publishedVersio

EFFECT OF FATIGUE ON RUNNING KINETIC ASYMMETRY IN NONCONTINUOUS & CONTINUOUS CONSTANT SPEED PROTOCOL

Kinetic asymmetries in running gait are well studied but their interaction with muscular fatigue, perceived exertion and/or metabolic stress, need further attention to understand and report limb laterality with fatigue progression during a non-continuous & a continuous constant speed protocols. For study, 13 young male runner's data for kinetic asymmetry (KA), stride rate (SR), blood lactate (BLa), muscular fatigue (RPEM) and overall body feel (RPEo) were collected. Kendall's tau-b reported a non-significant correlation between KA, SR and RPEM and a significant correlation between BLa, RPEo and RPEM whereas Tuckey post hoc test revealed non-significant effect of RPEM on KA and SR in both tests. Findings suggest that, observed KA with fatigue progression may be subject to inter-individual coordinated motor control based on overall running physiological state of body as there has no direct correlation been found with BLa, RPEM and RPEo in this study