A comprehensive analysis of the velocity-based method in the shoulder press exercise: stability of the load-velocity relationship and sticking region parameters

The purpose of this study was threefold: i) to analyse the load-velocity relationship of the shoulder press (SP) exercise, ii) to investigate the stability (intra-individual variability) of this load-velocity relationship for athletes with different relative strength levels, and after a 10-week velocity-based resistance training (VBT), and iii) to describe the velocity-time pattern of the SP: first peak velocity [V_max1], minimum velocity [V_min], and second peak velocity [V_max2]. This study involves a cross-sectional (T1, n = 48 subjects with low, medium and high strength levels) and longitudinal (T2, n = 24 subjects randomly selected from T1 sample) design. In T1, subjects completed a progressive loading test up to the 1RM in the SP exercise. The barbell mean, peak and mean propulsive velocities (MV, PV and MPV) were monitored. In T2, subjects repeated the loading test after 10 weeks of VBT. There were very close relationships between the %1RM and velocity attained in the three velocity outcomes (T1, R²: MV = 0.970; MPV = 0.969; PV = 0.954), being even stronger at the individual level (T1, R² = 0.973–0.997). The MPV attained at the 1RM (~0.19 m·s^-1) was consistent among different strength levels. Despite the fact that 1RM increased ~17.5% after the VBT programme, average MPV along the load-velocity relationship remained unaltered between T1 and T2 (0.69 ± 0.06 vs. 0.70 ± 0.06 m·s^-1). Lastly, the three key parameters of the velocity-time curve were detected from loads > 74.9% 1RM at 14.3% (V_max1), 46.1% (V_min), and 88.7% (V_max2) of the concentric phase. These results may serve as a practical guideline to effectively implement the velocity-based method in the SP exercise.     

Effects of Heavy Strength Training on Running Performance and Determinants of Running Performance in Female Endurance Athletes

Purpose

The purpose of the current study was to investigate the effects of adding strength training to normal endurance training on running performance and running economy in well-trained female athletes. We hypothesized that the added strength training would improve performance and running economy through altered stiffness of the muscle-tendon complex of leg extensors.

Methods

Nineteen female endurance athletes [maximal oxygen consumption (VO_2max): 53±3 ml∙kg^-1∙min^-1, 5.8 h weekly endurance training] were randomly assigned to either normal endurance training (E, n = 8) or normal endurance training combined with strength training (E+S, n = 11). The strength training consisted of four leg exercises [3 x 4–10 repetition maximum (RM)], twice a week for 11 weeks. Muscle strength, 40 min all-out running distance, running performance determinants and patellar tendon stiffness were measured before and after the intervention.

Results

E+S increased 1RM in leg exercises (40 ± 15%) and maximal jumping height in counter movement jump (6 ± 6%) and squat jump (9 ± 7%, p < 0.05). This was accompanied by increased muscle fiber cross sectional area of both fiber type I (13 ± 7%) and fiber type II (31 ± 20%) in m. vastus lateralis (p < 0.05), with no change in capillary density in m. vastus lateralis or the stiffness of the patellar tendon. Neither E+S nor E changed running economy, fractional utilization of VO_2max or VO_2max. There were also no change in running distance during a 40 min all-out running test in neither of the groups.

Conclusion

Adding heavy strength training to endurance training did not affect 40 min all-out running performance or running economy compared to endurance training only.     

Acute effects of different external compression with blood flow restriction on force-velocity profile during squat and bench press exercises

The aim was to compare the acute effects of bench press (BP) and squat (SQ) exercises with blood flow restriction (BFR) (40%, 60%, 80% and 100% of the complete arterial occlusion pressure (AOP)) and without BFR (CON) on the mean propulsive (Vel_MED) and maximum (Vel_MAX) bar velocity. Fourteen healthy, physically active males (age, 23.6 ± 4.1 years; height, 1.85 ± 0.11 m; body weight 85.4 ± 4.1 kg) took part in the study. There was one set for each testing condition (CON, 40%, 60%, 80% and 100%) with 6 repetitions for BP and 6 repetitions for SQ, at 60% of 1RM, and 3 minutes of recovery between sets. The results showed statistically significant differences of the sets with 80% BFR vs. CON (mean difference [MD] = 0.035 m · s^-1, p < 0.05, ES = 0.52 [1.02–0.03]) and 100% BFR sets vs. CON (MD = 0.074, p < 0.001, ES = 1.08 [1.79–0.38]) for BP. In the SQ exercise, statistically significant differences were found between 100% BFR vs. CON (DM = 0.031 m · s^-1, p < 0.05), vs. 100% BFR 40% (MD = 0.04 m · s^-1, p < 0.05). Trend analysis showed a statistically significant linear trend (F[1,9] = 34.9, p < 0.001, F[1,13] = 27.32, p < 0.001) for the Vel_MED in relation to the different levels of BFR. In conclusion, our results showed that BFR levels above ˜80% AOP (BP) and ˜100% AOP (SQ) produce a Vel_MED improvement at 60% 1RM.     

Affinity for phosphatidylinositol 4,5-bisphosphate determines muscarinic agonist sensitivity of Kv7 K+ channels

Kv7 K⁺-channel subunits differ in their apparent affinity for PIP₂ and are differentially expressed in nerve, muscle, and epithelia in accord with their physiological roles in those tissues. To investigate how PIP₂ affinity affects the response to physiological stimuli such as receptor stimulation, we exposed homomeric and heteromeric Kv7.2, 7.3, and 7.4 channels to a range of concentrations of the muscarinic receptor agonist oxotremorine-M (oxo-M) in a heterologous expression system. Activation of M₁ receptors by oxo-M leads to PIP₂ depletion through G_q and phospholipase C (PLC). Chinese hamster ovary cells were transiently transfected with Kv7 subunits and M₁ receptors and studied under perforated-patch voltage clamp. For Kv7.2/7.3 heteromers, the EC₅₀ for current suppression was 0.44 ± 0.08 µM, and the maximal inhibition (Inhib_max) was 74 ± 3% (n = 5–7). When tonic PIP₂ abundance was increased by overexpression of PIP 5-kinase, the EC₅₀ was shifted threefold to the right (1.2 ± 0.1 µM), but without a significant change in Inhib_max (73 ± 4%, n = 5). To investigate the muscarinic sensitivity of Kv7.3 homomers, we used the A315T pore mutant (Kv7.3^T) that increases whole-cell currents by 30-fold without any change in apparent PIP₂ affinity. Kv7.3^T currents had a slightly right-shifted EC₅₀ as compared with Kv7.2/7.3 heteromers (1.0 ± 0.8 µM) and a strongly reduced Inhib_max (39 ± 3%). In contrast, the dose–response curve of homomeric Kv7.4 channels was shifted considerably to the left (66 ± 8 nM), and Inhib_max was slightly increased (81 ± 6%, n = 3–4). We then studied several Kv7.2 mutants with altered apparent affinities for PIP₂ by coexpressing them with Kv7.3^T subunits to boost current amplitudes. For the lower affinity (Kv7.2 (R463Q)/Kv7.3^T) or higher affinity (Kv7.2 (R463E)/Kv7.3^T) channels, the EC₅₀ and Inhib_max were similar to Kv7.4 or Kv7.3^T homomers (0.12 ± 0.08 µM and 79 ± 6% [n = 3–4] and 0.58 ± 0.07 µM and 27 ± 3% [n = 3–4], respectively). The very low-affinity Kv7.2 (R452E, R459E, and R461E) triple mutant was also coexpressed with Kv7.3^T. The resulting heteromer displayed a very low EC₅₀ for inhibition (32 ± 8 nM) and a slightly increased Inhib_max (83 ± 3%, n = 3–4). We then constructed a cellular model that incorporates PLC activation by oxo-M, PIP₂ hydrolysis, PIP₂ binding to Kv7-channel subunits, and K⁺ current through Kv7 tetramers. We were able to fully reproduce our data and extract a consistent set of PIP₂ affinities.     

Microzooplankton Growth Rates Examined across a Temperature Gradient in the Barents Sea

Growth rates (µ) of abundant microzooplankton species were examined in field experiments conducted at ambient sea temperatures (−1.8–9.0°C) in the Barents Sea and adjacent waters (70–78.5°N). The maximum species-specific µ of ciliates and athecate dinoflagellates (0.33–1.67 d⁻¹ and 0.52–1.14 d⁻¹, respectively) occurred at temperatures below 5°C and exceeded the µ_max predicted by previously published, laboratory culture-derived equations. The opposite trend was found for thecate dinoflagellates, which grew faster in the warmer Atlantic Ocean water. Mixotrophic ciliates and dinoflagellates grew faster than their heterotrophic counterparts. At sub-zero temperatures, microzooplankton µ_max matched those predicted for phytoplankton by temperature-dependent growth equations. These results indicate that microzooplankton protists may be as adapted to extreme Arctic conditions as their algal prey.     

The Correlation between Running Economy and Maximal Oxygen Uptake: Cross-Sectional and Longitudinal Relationships in Highly Trained Distance Runners

A positive relationship between running economy and maximal oxygen uptake (V̇O_2max) has been postulated in trained athletes, but previous evidence is equivocal and could have been confounded by statistical artefacts. Whether this relationship is preserved in response to running training (changes in running economy and V̇O_2max) has yet to be explored. This study examined the relationships of (i) running economy and V̇O_2max between runners, and (ii) the changes in running economy and V̇O2max that occur within runners in response to habitual training. 168 trained distance runners (males, n = 98, V̇O_2max 73.0 ± 6.3 mL∙kg^-1∙min^-1; females, n = 70, V̇O_2max 65.2 ± 5.9 mL kg^-1∙min^-1) performed a discontinuous submaximal running test to determine running economy (kcal∙km^-1). A continuous incremental treadmill running test to volitional exhaustion was used to determine V̇O_2max 54 participants (males, n = 27; females, n = 27) also completed at least one follow up assessment. Partial correlation analysis revealed small positive relationships between running economy and V̇O_2max (males r = 0.26, females r = 0.25; P<0.006), in addition to moderate positive relationships between the changes in running economy and V̇O_2max in response to habitual training (r = 0.35; P<0.001). In conclusion, the current investigation demonstrates that only a small to moderate relationship exists between running economy and V̇O_2max in highly trained distance runners. With >85% of the variance in these parameters unexplained by this relationship, these findings reaffirm that running economy and V̇O_2max are primarily determined independently.     

Pharmacokinetics and Bioequivalence of Two Formulations of Febuxostat 40-Mg and 80-Mg Tablets: A Randomized,Open-Label, 4-Way Crossover Study in Healthy Chinese Male Volunteers

The present study aimed to investigate the pharmacokinetic properties of febuxostat in healthy Chinese male volunteers and evaluate whether the two formulations of febuxostat 40-mg and 80-mg tablets are bioequivalent. A randomized, open-label, 4-way crossover study was conducted in healthy Chinese male volunteers under fasting conditions. 24 eligible subjects were randomized in a 1:1:1:1 ratio to receive a single dose of test or reference formulation of febuxostat 40-mg or 80-mg tablet. The washout period between each administration was 1 week. Plasma febuxostat was quantified by a validated liquid chromatography-tandem mass spectrometry (LC-MS/MS) method. Tolerability was evaluated by monitoring adverse events, physical examinations, 12-lead ECG and laboratory tests. After single-dosing of 1 tablet of 40-mg febuxostat, the pharmacokinetic parameters of test and reference formulations were: T_max 1.22±0.87 and 1.85±1.03 h, C_max 1689.16±461.31 and 1613.80±608.43 ng·mL^-1, AUC_0-t 5139.87±1349.28 and 5517.91±2024.26 ng·mL^-1·h, AUC_0−∞ 5263.06±1339.16 and 5640.48±2040.22 ng·mL^-1·h, t_1/2 4.82±2.61 and 4.85±1.78 h, respectively. After single-dosing of 1 tablet of 80-mg febuxostat, the pharmacokinetic parameters of test and reference formulations were: T_max 1.71±1.21 and 2.23±1.55 h, C_max 2744.47±1157.44 and 2998.17±1200.13 ng·mL^-1, AUC_0-t 9634.03±2768.25 and 10467.95±3501.65 ng·mL^-1·h, AUC_0−∞ 9834.32±2730.51 and 10626.63±3504.08 ng·mL^-1·h, t_1/2 6.25±2.44 and 5.46±1.65 h, respectively. For single-dosing of 1 tablet of 40-mg febuxostat, 90% CIs for the test/reference ratio of AUC_0-t, AUC_0−∞ and C_max were 89.79 to 102.55, 90.14 to 102.56 and 93.99 to 129.63, respectively. For single-dosing of 1 tablet of 80-mg febuxostat, 90% CIs for the test/reference ratio of AUC_0-t, AUC_0−∞ and C_max were 86.67 to 100.00, 87.50 to 100.51 and 79.48 to 105.99, respectively. This single dose study revealed similar pharmacokinetic properties in healthy Chinese male volunteers as those found in Caucasic population. The test and reference febuxostat tablets formulations met the regulatory criteria for bioequivalence at 40-mg and 80-mg strengths in fasting healthy Chinese male volunteers.Trial Registration: Chictr.org ChiCTR-TTRCC-14004288     

Tennis Play Intensity Distribution and Relation with Aerobic Fitness in Competitive Players

The aims of this study were (i) to describe the relative intensity of simulated tennis play based on the cumulative time spent in three metabolic intensity zones, and (ii) to determine the relationships between this play intensity distribution and the aerobic fitness of a group of competitive players. 20 male players of advanced to elite level (ITN) performed an incremental on-court specific endurance tennis test to exhaustion to determine maximal oxygen uptake (VO_2max) and the first and second ventilatory thresholds (VT₁, VT₂). Ventilatory and gas exchange parameters were monitored using a telemetric portable gas analyser (K4 b², Cosmed, Rome, Italy). Two weeks later the participants played a simulated tennis set against an opponent of similar level. Intensity zones (1: low, 2: moderate, and 3: high) were delimited by the individual VO₂ values corresponding to VT₁ and VT₂, and expressed as percentage of maximum VO₂ and heart rate. When expressed relative to VO_2max, percentage of playing time in zone 1 (77 ± 25%) was significantly higher (p < 0.001) than in zone 2 (20 ± 21%) and zone 3 (3 ± 5%). Moderate to high positive correlations were found between VT₁, VT₂ and VO_2max, and the percentage of playing time spent in zone 1 (r = 0.68–0.75), as well as low to high inverse correlations between the metabolic variables and the percentage of time spent in zone 2 and 3 (r = -0.49–0.75). Players with better aerobic fitness play at relatively lower intensities. We conclude that players spent more than 75% of the time in their low-intensity zone, with less than 25% of the time spent at moderate to high intensities. Aerobic fitness appears to determine the metabolic intensity that players can sustain throughout the game.     

Higher Urinary Bisphenol A Concentration Is Associated with Unexplained Recurrent Miscarriage Risk: Evidence from a Case-Control Study in Eastern China

BackgroundEvidence about the association between Bisphenol A (BPA) and the risk of recurrent miscarriage (RM) in human being is still limited.ObjectiveWe evaluated the association of urinary BPA concentrations with RM in human being.MethodsA hospital-based 1:2 matched case-control study on RM was carried out in Suzhou and Kunshan in Jiangsu Province in China between August 2008 and November 2011. Total urinary BPA concentrations in 264 eligible urine samples (102 RM patients and 162 controls) were measured using liquid chromatography-tandem mass spectrometry (LC-MS/MS). The Wilcoxon test and conditional logistic regression were used to estimate the differences between the groups and odds ratios (OR) with 95% confidence intervals (CI), respectively.ResultsThe median ± IQR (interquartile range) (P₇₅-P₂₅) values of non-creatinine-adjusted total urinary BPA levels in the RM patients and the controls were 1.66±3.69ng/ml and 0.58±1.07ng/ml, respectively (0.98±2.67μg/g Cr (creatinine) and 0.40±0.77μg/g Cr. The adjusted BPA level was significantly higher in the RM patients than in the controls (Wilcoxon test, Z = 4.476, P<0.001). Higher level of urinary BPA was significantly associated with an increased risk of RM (P-trend <0.001). Compared to the groups with urinary BPA levels less than 0.16μg/g Cr, the women with levels of 0.40–0.93μg/g Cr and 0.93μg/g Cr or above had a significantly higher risk of RM (OR = 3.91, 95%CI: 1.23–12.45 and OR = 9.34, 95%CI: 3.06–28.44) that persisted after adjusting for confounding factors. The time from recently RM date to recruitment does not significantly influence the urinary BPA level (P = 0.090).ConclusionExposure to BPA may be associated with RM risk.     

Acute responses of muscle oxygen saturation during different cluster training configurations in resistance-trained individuals

This study compared the perceptual responses, physiological indicators and technical parameters between different training protocols focused on upper body exercises. A randomized crossover design was performed, and 12 trained individuals (age: 27.1 ± 5.7 years; height: 173.7 ± 10.7 cm; BMI: 23.9 ± 2.3) completed three resistance training sessions under different protocols separated by at least 72 h: traditional training (TT) (4 x 6 repetitions at 85% of 1RM with 120 s of rest between sets), cluster 1 (CL1) (4 x 2+2+2 repetitions at 85% of 1RM with 15 s of intra-rep rest and 80 s between sets), and cluster 2 (CL2) (24 repetitions at 85% of 1RM with 15 s of inter-set recovery). Before training, arterial blood pressure (BP) and repetitions to failure of pull-up and push-up (FT) were collected. Muscle oxygen saturation (SmO₂) in the chest and movement velocity were evaluated in barbell bench press during the training session. After finishing, lactate, BP, rate of perceived exertion and FT were assessed. The percentage of velocity loss (TT: 19.24%; CL1: 5.02% and CL2: 7.30%) in the bench press and lactate concentration (TT: 8.90 mmol·l^-1; CL1: 6.13 mmol·l^-1 and CL2: 5.48 mmol·l^-1) were significantly higher (p < 0.05) for TT compared to both CLs. RPE values were higher (p < 0.05) in TT compared to CL1 (7.95 a.u. vs. 6.91 a.u., respectively). No differences (p > 0.05) were found between protocols for SmO₂, BP, FT, pain or heart rate between set configurations. Cluster configurations allow one to maintain higher movement velocity and lower lactate and RPE values compared to a traditional configuration, but with similar concentrations of SmO₂.     

Prediction of muscle fiber composition using multiple repetition testing

Direct determination of muscle fiber composition is invasive and expensive, with indirect methods also requiring specialist resources and expertise. Performing resistance exercises at 80% 1RM is suggested as a means of indirectly estimating muscle fiber composition, though this hypothesis has never been validated against a direct method. The aim of the study was to investigate the relationship between the number of completed repetitions at 80% 1RM of back squat exercise and muscle fiber composition. Thirty recreationally active participants’ (10 females, 20 males) 1RM back squat load was determined, before the number of consecutive repetitions at 80% 1RM was recorded. The relationship between the number of repetitions and the percentage of fast-twitch fibers from vastus lateralis was investigated. The number of completed repetitions ranged from 5 to 15 and was independent of sex, age, 1RM, training frequency, training type, training experience, BMI or muscle fiber cross-sectional area. The percentage of fast-twitch muscle fibers was inversely correlated with the number of repetitions completed (r = –0.38, P = 0.039). Participants achieving 5 to 8 repetitions (n = 10) had significantly more fast-twitch muscle fibers (57.5 ± 9.5 vs 44.4 ± 11.9%, P = 0.013) than those achieving 11–15 repetitions (n = 11). The remaining participants achieved 9 or 10 repetitions (n = 9) and on average had equal proportion of fast- and slow-twitch muscle fibers. In conclusion, the number of completed repetitions at 80% of 1RM is moderately correlated with muscle fiber composition.     

Effects of heavy barbell hip thrust vs back squat on subsequent sprint performance in rugby players

The objective of this research was to compare the effect of Post-Activation Performance Enhancement (PAPE) exerted on the back squat (BS) versus the barbell hip thrust (HT) on the sprint performance (5- and 10-m). 17 male amateur rugby players participated in the study (age 22.14 ± 2.52 years; body mass 81.06 ± 9.6 kg; height 1.78 ± 0.05 m). All participants performed a dynamic maximum strength test (3RM) in BS and HT at maximum speed. Two randomized sessions were performed inducing PAPE using BS or HT trough three series with three repetitions at 85% 1RM eight minutes before the sprint tests. An ANOVA of repeated measurement, found no differences in the time for 5-m (F = 0.398, P = 0.537, η²p = 0.024) or 10-m (F = 2.589, P = 0.127, η²p = 0.139). There were no significant differences in the Protocol effect between HT and BS in 5-m or 10-m (F = 2.963, P = 0.104, η²p = 0.156 and F = 1.472, P = 0.243 η²p = 0.084, respectively). There were also no differences in the Time x Protocol interaction at 5-m (F = 0.001, P = 0.976, η²p < 0.001) or 10-m (F = 4.174, P = 0.058, η²p = 0.207). The effect size obtained in the results of the sprint tests was small in both exercises (ES < 0.2). None of the BS or HT exercises performed with heavy load induced a significant PAPE phenomenon on the ability to sprint in rugby players.     

Determination of base and backbone contributions to the thermodynamics of premelting and melting transitions in B DNA

In previous papers of this series the temperature-dependent Raman spectra of poly(dA)·poly(dT) and poly(dA–dT)·poly(dA–dT) were used to characterize structurally the melting and premelting transitions in DNAs containing consecutive A·T and alternating A·T/T·A base pairs. Here, we describe procedures for obtaining thermodynamic parameters from the Raman data. The method exploits base-specific and backbone-specific Raman markers to determine separate thermodynamic contributions of A, T and deoxyribosyl-phosphate moieties to premelting and melting transitions. Key findings include the following: (i) Both poly(dA)·poly(dT) and poly(dA–dT)· poly(dA–dT) exhibit robust premelting transitions, due predominantly to backbone conformational changes. (ii) The significant van’t Hoff premelting enthalpies of poly(dA)·poly(dT) [ΔH_vH^pm = 18.0 ± 1.6 kcal·mol^–1 (kilocalories per mole cooperative unit)] and poly(dA–dT)·poly(dA–dT) (ΔH_vH^pm = 13.4 ± 2.5 kcal·mol^–1) differ by an amount (~4.6 kcal·mol^–1) estimated as the contribution from three-centered inter-base hydrogen bonding in (dA)_n·(dT)_n tracts. (iii) The overall stacking free energy of poly(dA)· poly(dT) [–6.88 kcal·mol_bp^–1 (kilocalories per mole base pair)] is greater than that of poly(dA–dT)· poly(dA–dT) (–6.31 kcal·mol_bp^–1). (iv) The difference between stacking free energies of A and T is significant in poly(dA)·poly(dT) (ΔΔG_st = 0.8 ± 0.3 kcal· mol_bp^–1), but marginal in poly(dA–dT)·poly(dA–dT) (ΔΔG_st = 0.3 ± 0.3 kcal·mol_bp^–1). (v) In poly(dA)· poly(dT), the van’t Hoff parameters for melting of A (ΔH_vH^A = 407 ± 23 kcal·mol^–1, ΔS_vH^A = 1166 ± 67 cal·°K^–1·mol^–1, ΔG_vH(25°C)^A = 60.0 ± 3.2 kcal·mol^–1) are clearly distinguished from those of T (ΔH_vH^T = 185 ± 38 kcal·mol^–1, ΔS_vH^T = 516 ± 109 cal·°K^–1·mol^–1, ΔG_vH(25°C)^T = 27.1 ± 5.5 kcal·mol^–1). (vi) Similar relative differences are observed in poly(dA–dT)· poly(dA–dT) (ΔH_vH^A = 333 ± 54 kcal·mol^–1, ΔS_vH^A = 961 ± 157 cal·°K^–1·mol^–1, ΔG_vH(25°C)^A = 45.0 ± 7.6 kcal· mol^–1; ΔH_vH^T = 213 ± 30 kcal·mol^–1, ΔS_vH^T = 617 ± 86 cal·°K^–1·mol^–1, ΔG_vH(25°C)^T = 29.3 ± 4.9 kcal·mol^–1). The methodology employed here distinguishes thermodynamic contributions of base stacking, base pairing and backbone conformational ordering in the molecular mechanism of double-helical B DNA formation.     

USEFULNESS AND METABOLIC IMPLICATIONS OF A 60-SECOND REPEATED JUMPS TEST AS A PREDICTOR OF ACROBATIC JUMPING PERFORMANCE IN GYMNASTS

Gymnastics floor exercises are composed of a set of four to five successive acrobatic jumps usually called a “series”. The aims of the study were: 1) to relate the acrobatic gymnastics performance of these series with a repeated jumps test of similar duration (R60), 2) to study the relation between R60 and physiological parameters (heart rate and blood lactate), and the performance obtained in different kinds of jumps, 3) to confirm whether R60, executed without a damped jumping technique, can be considered an anaerobic lactic power test. Twenty male and twenty-four female gymnasts performed three repeated jumps tests for 5 s (R5), 10 s (R10) and 60 s (R60) and vertical jumps, such as drop jumps (DJ), squat jumps (SJ) and countermovement jumps (CMJ). We assessed heart rate (HR) and blood lactate during R10 and R60. The average values of the maximal blood lactate concentration (L_max) after R10 (males = 2.5±0.6 mmol · l⁻¹; females = 2.1±0.8 mmol · l⁻¹) confirm that anaerobic glycolysis is not activated to a high level. In R60, the L_max (males = 7.5±1.7 mmol · l⁻¹ females = 5.9±2.1 mmol · l⁻¹) that was recorded does not validate R60 as an anaerobic lactic power test. We confirmed the relation between the average power obtained in R60 (R60Wm) and the acrobatic performance on the floor. The inclusion in the multiple regression equation of the best power in DJ and the best flight-contact ratio (FC) in R5 confirms the influence of other non-metabolic components on the variability in R60 performance, at least in gymnasts.     

Low-Volume High-Intensity Interval Training in a Gym Setting Improves Cardio-Metabolic and Psychological Health

Background

Within a controlled laboratory environment, high-intensity interval training (HIT) elicits similar cardiovascular and metabolic benefits as traditional moderate-intensity continuous training (MICT). It is currently unclear how HIT can be applied effectively in a real-world environment.

Purpose

To investigate the hypothesis that 10 weeks of HIT, performed in an instructor-led, group-based gym setting, elicits improvements in aerobic capacity (VO_2max), cardio-metabolic risk and psychological health which are comparable to MICT.

Methods

Ninety physically inactive volunteers (42±11 y, 27.7±4.8 kg.m^-2) were randomly assigned to HIT or MICT group exercise classes. HIT consisted of repeated sprints (15–60 seconds, >90% HR_max) interspersed with periods of recovery cycling (≤25 min.session^-1, 3 sessions.week^-1). MICT participants performed continuous cycling (~70% HR_max, 30–45 min.session^-1, 5 sessions.week^-1). VO_2max, markers of cardio-metabolic risk, and psychological health were assessed pre and post-intervention.

Results

Mean weekly training time was 55±10 (HIT) and 128±44 min (MICT) (p<0.05), with greater adherence to HIT (83±14% vs. 61±15% prescribed sessions attended, respectively; p<0.05). HIT improved VO_2max, insulin sensitivity, reduced abdominal fat mass, and induced favourable changes in blood lipids (p<0.05). HIT also induced beneficial effects on health perceptions, positive and negative affect, and subjective vitality (p<0.05). No difference between HIT and MICT was seen for any of these variables.

Conclusions

HIT performed in a real-world gym setting improves cardio-metabolic risk factors and psychological health in physically inactive adults. With a reduced time commitment and greater adherence than MICT, HIT offers a viable and effective exercise strategy to target the growing incidence of metabolic disease and psychological ill-being associated with physical inactivity.     

PHYSIOLOGICAL DEMANDS OF YOUNG WOMEN'S COMPETITIVE GYMNASTIC ROUTINES

The objective of this study was to investigate the physiological indices of competitive routines in women''s artistic gymnastics by characterizing post-exercise heart rate (HR), oxygen uptake (VO₂) and peak blood lactate concentration (L_max) in a group of eight young elite-oriented female gymnasts. HR was continuously monitored with Polar RS400 monitors during the test event simulating a competition environment. Within 5 s of the end of each routine, the breath-by-breath gas analyser mask was placed on the face to record VO₂. VO₂max was calculated by the backward extrapolation method of the VO₂ recovery curve. L_max was obtained during recovery (min 1, 3, 5, 7 and 10) subsequent to each event. One week later, HR, VO₂ and L_max were measured during an incremental continuous treadmill test. The treadmill test was confirmed as the assessment with the highest physiological demand. The gymnasts reached their highest values of HR (183-199 beats · min^-1), VO₂/Bm (33-44 ml · kg^-1 · min^-1) and L_max (7-9 mmol · l^-1) in the floor and uneven bars exercises. The vault was the event with the lowest HR (154-166 beats · min^-1) and L_max (2.4-2.6 mmol · l^-1), and the balance beam had the lowest VO₂ (27-35 ml · kg^-1 · min^-1). The mean relative peak intensities attained in the different events, which ranged from 65 to 85% of the individual VO₂max and HRmax recorded in the laboratory, suggest that cardiorespiratory and metabolic demands are higher than previously indicated. The high percentage of VO₂ measured, particularly after the floor event, suggests that aerobic power training should not be neglected in women''s artistic gymnastics.     

Effects of resistance training on hypertrophy,strength and tensiomyography parameters of elbow flexors: role of eccentric phase duration

The aim of the study was to compare the effects of two different training protocols, which differ in the duration of the eccentric phase, on the one-repetition maximum (1RM), thickness and contractile properties of elbow flexors. Twenty untrained college students were randomly divided into two experimental groups, based on the training tempo: FEG (Faster Eccentric Group: 1/0/1/0) and SEG (Slower Eccentric Group: 4/0/1/0). Training intervention was a biceps bending exercise, conducted twice a week for 7 weeks. The intensity (60–70% RM), sets (3–4) and rest intervals (120 s) were held constant, while repetitions were performed until it was not possible to maintain a set duration. In the initial and final measurements, 1RM, muscle thickness and tensiomyography parameters – contraction time (Tc) and radial deformation (Dm) – were evaluated. An ANCOVA model (using baseline outcomes as covariates) was applied to determine between-group differences at post-test, while Pearson’s product-moment correlation coefficient was used to investigate the relationship between absolute changes in muscle thickness and Dm. Muscle strength increase was greater for SEG than for FEG (6.0 ± 1.76 vs. 3.30 ± 2.26 kg, p < 0.01). In both groups muscle thickness increased equally (FEG: 3.24 ± 2.01 vs. SEG: 3.57 ± 1.17 mm, p < 0.01), while an overall reduction in Dm was observed (FEG: 1.99 ± 1.20 vs. SEG: 2.26 ± 1.03 mm, p < 0.01). Values of Tc remained unchanged. A significant negative relationship was observed between changes in muscle thickness and Dm (r = -0.763, Adj.R² = 0.560, p < 0.01). These results indicate that the duration of the eccentric phase has no effect on muscle hypertrophy in untrained subjects, but that slower eccentric movement significantly increases 1RM.     

PPARA Intron Polymorphism Associated with Power Performance in 30-s Anaerobic Wingate Test

To date, polymorphisms in several genes have been associated with a strength/power performance including alpha 3 actinin, ciliary neurotrophic factor, vitamin D receptor, or angiotensin I converting enzyme, underlining the importance of genetic component of the multifactorial strength/power-related phenotypes. The single nucleotide variation in peroxisome proliferator-activated receptor alpha gene (PPARA) intron 7 G/C (rs4253778; g.46630634G>C) has been repeatedly found to play a significant role in response to different types of physical activity. We investigated the effect of PPARA intron 7 G/C polymorphism specifically on anaerobic power output in a group of 77 elite male Czech ice hockey players (18–36 y). We determined the relative peak power per body weight (P_max.kg⁻¹) and relative peak power per fat free mass (W.kg⁻¹ _FFM) during the 30-second Wingate Test (WT30) on bicycle ergometer (Monark 894E Peak bike, MONARK, Sweden). All WT30s were performed during the hockey season. Overall genotype frequencies were 50.6% GG homozygotes, 40.3% CG heterozygotes, and 9.1% CC homozygotes. We found statistically significant differences in P_max.kg⁻¹ and marginally significant differences in P_max.kg⁻¹ _FFM values in WT30 between carriers and non-carriers for C allele (14.6±0.2 vs. 13.9±0.3 W.kg⁻¹ and 15.8±0.2 vs. 15.2±0.3 W.kg⁻¹ _FFM, P = 0.036 and 0.12, respectively). Furthermore, P_max.kg⁻¹ _FFM strongly positively correlated with the body weight only in individuals with GG genotypes (R = 0.55; p<0.001). Our results indicate that PPARA 7C carriers exhibited higher speed strength measures in WT30. We hypothesize that C allele carriers within the cohort of trained individuals may possess a metabolic advantage towards anaerobic metabolism.     

THE COMPETITIVE DEMANDS OF ELITE MALE RINK HOCKEY

The aim of this study was to simulate the activity pattern of rink hockey by designing a specific skate test (ST) to study the energy expenditure and metabolic responses to this intermittent high-intensity exercise and extrapolate the results from the test to competition. Six rink hockey players performed, in three phases, the 20-metre multi-stage shuttle roller skate test, a tournament match and the ST. Heart rate was monitored in all three phases. Blood lactate, oxygen consumption, ventilation and respiratory exchange ratio were also recorded during the ST. Peak HR was 190.7±7.2 beats · min⁻¹. There were no differences in peak HR between the three tests. Mean HR was similar between the ST and the match (86% and 87% of HR_max, respectively). Peak and mean ventilation averaged 111.0±8.8 L · min⁻¹ and 70.3±14.0 L ^· min⁻¹ (60% of V_Emax), respectively. VO_2max was 56.3±8.4 mL · kg⁻¹ · min⁻¹, and mean oxygen consumption was 40.9±7.9 mL · kg^{−1 ·} min⁻¹ (70% of VO_2max). Maximum blood lactate concentration was 7.2±1.3 mmol · L-1. ST yielded an energy expenditure of 899.1±232.9 kJ, and energy power was 59.9±15.5 kJ · min⁻¹. These findings suggest that the ST is suitable for estimating the physiological demands of competitive rink hockey, which places a heavy demand on the aerobic and anaerobic systems, and requires high energy consumption.     

Low-resolution structure of the soluble domain GPAA1 (yGPAA170–247) of the glycosylphosphatidylinositol transamidase subunit GPAA1 from Saccharomyces cerevisiae

The GPI (glycosylphosphatidylinositol) transamidase complex catalyses the attachment of GPI anchors to eukaryotic proteins in the lumen of ER (endoplasmic reticulum). The Saccharomyces cerevisiae GPI transamidase complex consists of the subunits yPIG-K (Gpi8p), yPIG-S (Gpi17p), yPIG-T (Gpi16p), yPIG-U (CDC91/GAB1) and yGPAA1. We present the production of the two recombinant proteins yGPAA1^70–247 and yGPAA1^70–339 of the luminal domain of S. cerevisiae GPAA1, covering the amino acids 70–247 and 70–339 respectively. The secondary structural content of the stable and monodisperse yGPAA1^70–247 has been determined to be 28% α-helix and 27% β-sheet. SAXS (small-angle X-ray scattering) data showed that yGPAA1^70–247 has an R_g (radius of gyration) of 2.72±0.025 nm and D_max (maximum dimension) of 9.14 nm. These data enabled the determination of the two domain low-resolution solution structure of yGPAA1^70–247. The large elliptical shape of yGPAA1^70–247 is connected via a short stalk to the smaller hook-like domain of 0.8 nm in length and 3.5 nm in width. The topological arrangement of yGPAA1^70–247 will be discussed together with the recently determined low-resolution structures of yPIG-K^24–337 and yPIG-S^38–467 from S. cerevisiae in the GPI transamidase complex.