The Effects of Altering the Concentric/Eccentric Phase Times on EMG Response, Lactate Accumulation and Work Completed when Training to Failure

AbstractThis study compared the electromyographic response, the blood lactate concentration (BLC), and the maximum number of repetitions (MNR) between protocols of different concentric/eccentric duration taken to muscle failure. This comparison may help to understand how different concentric/eccentric duration may influence performance and the central and metabolic responses in trained men. Seventeen strength-trained men performed two protocols in a counterbalanced design. Three sets of the Smith bench press exercise were performed to failure at 60% of the one-repetition maximum (1RM) using each protocol (4-s concentric/2-s eccentric [4 s: 2 s]; and 2-s concentric/4-s eccentric [2 s: 4 s]). The normalized root mean square (EMGRMS) and the mean frequency (EMGMF) of the electromyographic signals for the pectoralis major and the triceps brachii were compared in the first, middle, and last repetitions. The BLC was assessed at rest, during and after the test sessions. To compare the EMG and BLC, a 3-way ANOVA with repeated measures with a post hoc Tukey’s test was used. To compare the MNR performed across the sets, an ANOVA-type rank test with the Dunn’s post hoc test was used. The ANOVA indicated a greater EMGRMS for Protocol 4 s: 2 s in the pectoralis major and a lower EMGMF for Protocol 4 s: 2 s in the triceps brachii at the middle and last repetitions. Both protocols increased the EMGRMS and decreased the EMGMF across repetitions. Despite the results show different levels of activation and neuromuscular fatigue between protocols, the BLC and the MNR were similar.

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Which common NIRS variable reflects muscle estimated lactate threshold most closely?

Applied Physiology Nutrition and Metabolism ◽

10.1139/h06-069 ◽

2006 ◽

Vol 31 (5) ◽

pp. 612-620 ◽

Cited By ~ 29

Author(s):

Lixin Wang ◽

Takahiro Yoshikawa ◽

Taketaka Hara ◽

Hayato Nakao ◽

Takashi Suzuki ◽

...

Keyword(s):

Lactate Threshold ◽

Near Infrared ◽

Ventilatory Threshold ◽

Lactate Concentration ◽

Blood Lactate Concentration ◽

Oxygenation Index ◽

Muscle Lactate ◽

Tissue Oxygenation Index ◽

The Mean ◽

Tissue Hemoglobin

Various near-infrared spectroscopy (NIRS) variables have been used to estimate muscle lactate threshold (LT), but no study has determined which common NIRS variable best reflects muscle estimated LT. Establishing the inflection point of 2 regression lines for deoxyhaemoglobin (ΔHHbi.p.), oxyhaemoglobin (ΔO2Hbi.p.), and tissue oxygenation index (TOIi.p.), as well as for blood lactate concentration, we then investigated the relationships between NIRS variables and ventilatory threshold (VT), LT, or maximal tissue hemoglobin index (nTHImax) during incremental cycling exercise. ΔHHbi.p. and TOIi.p. could be determined for all 15 subjects, but ΔO2Hbi.p. was determined for only 11 subjects. The mean absolute values for the 2 measurable slopes of the 2 continuous linear regression lines exhibited increased changes in 3 NIRS variables. The workload and VO2 at ΔO2Hbi.p. and nTHImax were greater than those at VT, LT, ΔHHbi.p., and TOIi.p.. For workload and VO2, ΔHHbi.p. was correlated with VT and LT, whereas ΔO2Hbi.p. was correlated with nTHImax, and TOIi.p. with VT and nTHImax. These findings indicate that ΔO2Hb strongly corresponds with local perfusion, and TOI corresponds with both local perfusion and deoxygenation, but that ΔHHb can exactly determine deoxygenation changes and reflect O2 metabolic dynamics. The finding of strongest correlations between ΔHHb and VT or LT indicates that ΔHHb is the best variable for muscle LT estimation.

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Effects of Adding Small Combat Games to Regular Taekwondo Training on Physiological and Performance Outcomes in Male Young Athletes

Frontiers in Physiology ◽

10.3389/fphys.2021.646666 ◽

2021 ◽

Vol 12 ◽

Author(s):

Ibrahim Ouergui ◽

Emerson Franchini ◽

Hamdi Messaoudi ◽

Hamdi Chtourou ◽

Anissa Bouassida ◽

...

Keyword(s):

Perceived Exertion ◽

Lactate Concentration ◽

Blood Lactate Concentration ◽

Random Order ◽

Performance Outcomes ◽

Rating Of Perceived Exertion ◽

Control Group ◽

Metabolic Demand ◽

Before And After ◽

Post Hoc

This study investigated the effect of area sizes (4 × 4, 6 × 6, and 8 × 8 m) and effort-pause ratios (free combat vs. 1:2) variation on the physiological and perceptive responses during taekwondo combats (Study 1). In a second study, the effects on physical performance of 8 weeks of small combat-based training added to regular taekwondo training were investigated (Study 2). In random order, 32 male taekwondo athletes performed six (i.e., two effort-to-pause ratios × three area sizes conditions) different 2-min taekwondo combats (Study 1). Thereafter (Study 2), they were randomly assigned to three experimental groups (4 × 4, 6 × 6, and 8 × 8 m) and an active control group (CG). Regarding Study 1, blood lactate concentration [La] before and after each combat, mean heart rate (HRmean) during each combat, and rating of perceived exertion (CR-10) immediately after each combat were assessed. Regarding Study 2, progressive specific taekwondo (PSTT) to estimate maximum oxygen consumption (VO2max), taekwondo-specific agility, and countermovement jump (CMJ) tests were administered before and after 8 weeks of training. Study 1 results showed that 4 × 4 m elicited lower HRmean values compared with 6 × 6 m (d = −0.42 [small], p = 0.030) and free combat induced higher values compared with the 1:2 ratio (d = 1.71 [large], p < 0.001). For [La]post, 4 × 4 m area size induced higher values than 6 × 6 m (d = 0.99 [moderate], p < 0.001) and 8 × 8 m (d = 0.89 [moderate], p < 0.001) and free combat induced higher values than 1:2 ratio (d = 0.69 [moderate], p < 0.001). Higher CR-10 scores were registered after free combat compared with 1:2 ratio (d = 0.44 [small], p = 0.007). For Study 2, VO2max increased after training [F(1, 56) =30.532, p < 0.001; post-hoc: d = 1.27 [large], p < 0.001] with higher values for 4 × 4 m compared with CG (d = 1.15 [moderate], p = 0.009). Agility performance improved after training [F(1, 56) = 4.419, p = 0.04; post-hoc: d = −0.46 [small], p = 0.04] and 4 × 4 m induced lower values in comparison with 6 × 6 m (d = −1.56 [large], p = 0.001) and CG (d = −0.77 [moderate], p = 0.049). No training type influenced CMJ performance. Smaller area size elicited contrasting results in terms of metabolic demand compared with larger sizes (i.e., lower HRmean but higher [La] and CR-10), whereas free combat induced variables' consistently higher values compared with imposed 1:2 ratio (Study 1). Taekwondo training is effective to improve VO2max and agility (Study 2), but small combat training modality should be investigated further.

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Effects of Dietary L-Arginine Intake on Cardiorespiratory and Metabolic Adaptation in Athletes

International Journal of Sport Nutrition and Exercise Metabolism ◽

10.1123/ijsnem.19.4.355 ◽

2009 ◽

Vol 19 (4) ◽

pp. 355-365 ◽

Cited By ~ 25

Author(s):

Raul Bescós ◽

Carlos Gonzalez-Haro ◽

Pere Pujol ◽

Franchek Drobnic ◽

Eulalia Alonso ◽

...

Keyword(s):

Repeated Measures ◽

Control Diet ◽

Lactate Concentration ◽

Blood Lactate Concentration ◽

Physiological Parameters ◽

Physiological Adaptation ◽

Metabolic Adaptation ◽

High Doses ◽

Plasma Nitrate ◽

Level Of Significance

To assess the effect of diet enrichment with L-arginine or supplementation at high doses on physiological adaptation during exercise, 9 athletes followed 3 different diets, each over 3 consecutive days, with a wash-out period of 4 d between training sessions: control diet (CD), 5.5 ± 0.3 g/d of L-arginine; Diet 1 (rich in L-arginine food), 9.0 ± 1.1 g/d of L-arginine; and Diet 2 (the same as CD but including an oral supplement of 15 g/d), 20.5 ± 0.3 g/d of L-arginine. Plasma nitrate levels of each participant were determined on the day after each treatment. Participants performed a submaximal treadmill test (initial speed 10–11 km/hr, work increments 1 km/hr every 4 min until 85–90% VO2max, and passive recovery periods of 2 min). Oxygen uptake and heart rate were monitored throughout the test. Blood lactate concentration ([La−]b) was determined at the end of each stage. Repeated-measures ANOVA and paired Student’s t tests were used to compare the various physiological parameters between diets. The level of significance was set at p < .05. [La−]b showed a significant effect at the 5-min time point between CD and Diet 2 (CD 3.0 ± 0.5 mM, Diet 2 2.5 ± 0.5 mM, p = .03), but this tendency was not found at higher exercise intensities. No significant differences were observed in any of the cardiorespiratory or plasma nitrate levels. In conclusion, dietary L-arginine intake on the days preceding the test does not improve physiological parameters during exercise.

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The influence of different screw tightening forces on the vertical misfit of implant-supported frameworks

Journal of Applied Oral Science ◽

10.1590/s1678-77572005000200005 ◽

2005 ◽

Vol 13 (2) ◽

pp. 120-125 ◽

Cited By ~ 3

Author(s):

Diego Klee de Vasconcellos ◽

Marco Antonio Bottino ◽

Renato Sussumu Nishioka ◽

Luiz Felipe Valandro ◽

Elza Maria Valadares da Costa

Keyword(s):

Repeated Measures ◽

In Vitro Study ◽

Pairwise Comparisons ◽

Tukey Test ◽

Nickel Chromium ◽

Marginal Discrepancy ◽

The Mean ◽

Post Hoc ◽

One Way Anova

OBJECTIVES: The present in vitro study was designed to compare the differences in the vertical misfit of implant-supported frameworks using three different forces for tightening the bridge locking screws: fastening by hand until first resistance, and using torque drivers with 10 and 20Ncm. METHODS: The investigation was conducted based on the results given by 9 six-unit nickel-chromium (2 abutments/ 4 pontics) screw-retained implant-supported frameworks. The structures were exposed to simulated porcelain firings. The marginal misfit measurements were made using a traveling measuring microscope at selected screw tightening forces: fastening by hand until first resistance, and using torque drivers with 10 and 20Ncm. The results were submitted to one-way ANOVA with repeated measures on one factor, and post hoc pairwise comparisons using Tukey test (5%). RESULTS: The mean marginal misfit of the frameworks, fastening the screws by hand until first resistance, was 41.56µm (SD±12.45µm). The use of torque driver devices caused a significant reduction in marginal opening (p<0.05). With the lowest torque available (10Ncm), the mean marginal discrepancy at the abutment-framework interface was reduced an average of 52% to a mean marginal opening of 19.71µm (SD±2.97µm). After the use of the 20Ncm torque driver, the mean marginal discrepancy of the frameworks was reduced an average of 69% to a mean marginal opening of 12.82µm (SD±4.0µm). Comparing the use of torque drivers with 10 and 20 Ncm torque, the means are not significantly different from one another. CONCLUSION: The seating force has an important effect on the vertical misfit measurements, once it may considerably narrow the vertical misfit gaps at the abutment-framework interface, thus leading to a misjudgment of the real marginal situation.

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Repetitions to failure increase pectoralis major activation with similar neuromuscular fatigue in trained men

Journal of Physical Education ◽

10.4025/jphyseduc.v32i1.3214 ◽

2020 ◽

Vol 32 (1) ◽

Author(s):

Mateus Camargos Gomes ◽

Lucas Túlio Lacerda ◽

Marina Gurgel Simões ◽

Rodrigo César Ribeiro Diniz ◽

Mauro Heleno Chagas ◽

...

Keyword(s):

Repeated Measures ◽

Muscle Activation ◽

Rest Period ◽

Neuromuscular Fatigue ◽

Pectoralis Major ◽

Effective Strategy ◽

Repetition Maximum ◽

Post Hoc ◽

Repetitions To Failure ◽

Determining Factor

Resistance training protocols performed to muscle failure (MF) have been employed in an attempt to maximize activation and neuromuscular fatigue. Therefore, the aim of this study was to compare the surface electromyography amplitude (EMGRMS) and frequency (EMGFREQ) of the pectoralis major between protocols performed to MF and non muscle failure (NMF). Seven trained men performed three sets at 60% of a repetition maximum, with a 3 min rest period and a 6s repetition duration. MF protocol was performing with maximum number of repetitions in all sets, while in NMF protocol subjects performed 6 repetitions in 3 sets. For data analysis two two-way repeated measures ANOVAs (Protocol x Repetition) were used and when necessary, Bonferroni post hoc was performed. The EMGRMS was higher in the protocol MF compare to NMF, but there was no difference in EMGFREQ between protocols. Although there were no significant differences in the frequency domain between protocols, perform repetitions to MF was a determining factor to generate higher amplitude of the electromyography signal. Thus, perform repetitions to MF could be considered an effective strategy to increase muscle activation in trained individuals, however, with similar neuromuscular fatigue.

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Acute Cardiometabolic and Perceptual Responses to Individual and Group-Based Body-Weight Resistance Exercise in Girls

Pediatric Exercise Science ◽

10.1123/pes.2020-0248 ◽

2021 ◽

pp. 1-10

Author(s):

Jeanette M. Ricci ◽

Katharine D. Currie ◽

Todd A. Astorino ◽

Karin A. Pfeiffer

Keyword(s):

Heart Rate ◽

Body Weight ◽

Oxygen Uptake ◽

Perceived Exertion ◽

Lactate Concentration ◽

Blood Lactate Concentration ◽

Peak Oxygen Uptake ◽

Acute Responses ◽

Maximal Aerobic Speed ◽

The Mean

Girls’ acute responses to group-based high-intensity interval exercise (HIIE) are not well characterized. Purpose: To compare acute responses to treadmill-based HIIE (TM) and body-weight resistance exercise circuit (CIRC) and to CIRC performed in a small-group setting (group CIRC). Method: Nineteen girls (9.1 [1.1] y) completed exercise testing on a TM to determine peak oxygen uptake, peak heart rate (HRpeak), and maximal aerobic speed. The TM involved eight 30-second sprints at 100% maximal aerobic speed. The CIRC consisted of 8 exercises of maximal repetitions performed for 30 seconds. Each exercise bout was followed by 30 seconds of active recovery. The blood lactate concentration was assessed preexercise and postexercise. The ratings of perceived exertion, affective valence, and enjoyment were recorded at preexercise, Intervals 3 and 6, and postexercise. Results: The mean heart rate was higher during group CIRC (92% [7%] HRpeak) than CIRC (86% [7%] HRpeak) and TM (85% [4%] HRpeak) ( = .49). The mean oxygen uptake equaled 76% (11%) of the peak oxygen uptake for CIRC and did not differ from TM (d = 0.02). The CIRC elicited a greater postexercise blood lactate concentration versus TM (5.8 [1.7] vs 1.4 [0.4] mM, d = 3.61). The perceptual responses were similar among conditions (P > .05), and only the rating of perceived exertion increased during exercise ( = .78). Conclusion: Whether performed individually or in a small group, CIRC represents HIIE and may be a feasible alternative to running-based HIIE.

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Continuous increase in blood lactate concentration during different ramp exercise protocols

Journal of Applied Physiology ◽

10.1152/jappl.1989.66.3.1104 ◽

1989 ◽

Vol 66 (3) ◽

pp. 1104-1107 ◽

Cited By ~ 23

Author(s):

M. E. Campbell ◽

R. L. Hughson ◽

H. J. Green

Keyword(s):

Blood Lactate ◽

Lactate Concentration ◽

Blood Lactate Concentration ◽

Continuous Model ◽

Work Rate ◽

Transformation Model ◽

Mean Square ◽

Log Transformation ◽

Ramp Exercise ◽

The Mean

The applicability of a continuous model description of the blood lactate concentration [( La-]) vs. O2 uptake (VO2) relationship was studied in nine healthy male volunteers during three different ramp exercise protocols. The work rate was increased at either 8, 15, or 50 W/min. The continuous model for [La-] = a + b exp(cVO2) was compared statistically with a previously proposed log-log transformation model for the [La-] and VO2 variables. It was found that the mean square error was significantly less for the continuous as opposed to the log-log model (P less than 0.01) by analysis of variance pooled across all three ramp slopes. The mean square errors from the individual ramp slopes were also significantly less for the continuous model by paired t test (P less than 0.05). It was observed that the major contributor to the increased error of the log-log model was at VO2's at or above the intersection point (lactate threshold) of the two linear log-transformed segments. The log-log transformation does not appear to relate to any physiological process. The lactate slope index, taken as the point where the slope of the relationship between [La-] and VO2 (i.e., d[La-]/dVO2) equaled 1, occurred at a mean VO2 of 2.25 and 2.37 l/min for the 15- and 8-W/min ramp slopes, respectively, but at 2.76 l/min for the 50-W/min ramp (P less than 0.05). It is concluded that [La-] increases as a continuous function with respect to VO2 across a wide range of ramp work rate slopes.

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Lactate-guided conditioning program using variable exercise intensities improves fitness and alters muscle enzyme activity but not inflammatory response in horses

Comparative Exercise Physiology ◽

10.3920/cep160019 ◽

2016 ◽

Vol 12 (4) ◽

pp. 183-192

Author(s):

A.L. Fisher ◽

H.M. Greene ◽

R.J. Talmadge ◽

Y.S. Nout-Lomas

Keyword(s):

Repeated Measures ◽

Lactate Concentration ◽

Blood Lactate Concentration ◽

Exercise Bout ◽

Muscle Enzyme ◽

Speed Increase ◽

Amyloid A ◽

Inflammatory State ◽

Response To Exercise ◽

Incremental Step

Blood lactate concentration ([LA]) response to exercise challenges can be used to assess fitness in horses. Most equine conditioning programs (CP) that have been studied are based on regular bouts of exercise of similar to increasing levels of intensity. We hypothesised that a lactate-guided CP implementing 2× weekly short-duration high-intensity exercise bouts and 1× weekly low-intensity longer-duration exercise bout effectively increases fitness in horses. Six untrained adult horses followed a 12 week CP that consisted of 2× weekly exercise on an equine treadmill (6% incline) for 25 min at a velocity at which [LA] was 4.0 mmol/l (VLA4.0) and 1× weekly for 45 min at a velocity at which [LA] was 2.5 mmol/l (VLA2.5). VLA2.5 and VLA4.0 were determined by incremental-step standardised-exercisetest (SET) before the CP and adjusted every 3 weeks. Blood was collected for [LA], creatine kinase (CK), aspartate aminotransferase (AST), serum amyloid A (SAA), and fibrinogen (Fb) before each speed increase and 30 min, 2, 4, and 24 h after termination of the SET, when [LA] was ≥4.0 mmol/l. Repeated-measures ANOVA was used for analysis. During each SET horses showed increases in heart rate (P<0.0001), packed cell volume (P=0.003), and [LA] (P=0.002). Throughout the CP, VLA2.5 increased from 5.6±0.2 to 6.7±0.3 m/s (P<0.05) and VLA4.0 increased from 6.0±0.2 to 7.4±0.3 m/s (P<0.01). CK, AST, SAA, and Fb did not increase following submaximal exercise. CK and AST activity were attenuated throughout the 12 week CP (P<0.05). This lactate-guided CP was effective at increasing fitness based on achieving higher speeds during the SETs and did not appear to have deleterious effects on the horses’ muscular system or inflammatory state.

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Gas exchange and lactate anaerobic thresholds: inter- and intraevaluator agreement

Journal of Applied Physiology ◽

10.1152/jappl.1985.58.6.2082 ◽

1985 ◽

Vol 58 (6) ◽

pp. 2082-2089 ◽

Cited By ~ 75

Author(s):

L. B. Gladden ◽

J. W. Yates ◽

R. W. Stremel ◽

B. A. Stamford

Keyword(s):

Gas Exchange ◽

Linear Regression ◽

Computer Program ◽

Blood Lactate ◽

Intraclass Correlation ◽

Lactate Concentration ◽

Blood Lactate Concentration ◽

The Mean ◽

Graph Sets ◽

Better Than

Twenty-four coded graph sets of gas exchange variables and blood lactate concentration (LA) plotted against time at 15-s intervals were analyzed by nine evaluators who determined the gas exchange (ATGE) and LA (ATLA) anaerobic thresholds. In addition, ATGE and ATLA were determined by a linear regression computer program. Agreement between ATGE and ATLA was poor; the median intraclass correlation coefficient (ri) was 0.53. Among evaluators, ATLA agreement (median ri = 0.81) was better than ATGE agreement (median ri = 0.70). In general, the ability of any evaluator to choose similar values from duplicate plots for either ATGE (median ri = 0.97) or ATLA (median ri = 0.995) was good. There was better agreement between the mean ATLA of the evaluators and the computer ATLA (ComLA) (ri = 0.88) than between the mean ATGE of the evaluators and the computer ATGE (ComVE), (ri = 0.58). Agreement between ComVE and ComLA was poor (ri = 0.29). These results suggest that ATGE does not accurately predict ATLA and that different evaluators choose different thresholds from the same data. Further assessment of the validity and precision of ATGE based on breath-by-breath and minute-by-minute data is needed.

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The Effects of Ovarian Encapsulation on Morphology and Expression of Apoptosis-Related Genes in Vitrified Mouse Ovary

Journal of Reproduction & Infertility ◽

10.18502/jri.v22i1.4992 ◽

2020 ◽

Author(s):

Atefeh Shirazi Tehrani ◽

Tahereh Mazoochi ◽

Maryam Akhavan Taheri ◽

Esmat Aghadavood ◽

Mojdeh Salehnia

Keyword(s):

Alginate Hydrogel ◽

Mouse Ovary ◽

Hematoxylin And Eosin ◽

Group 3 ◽

The Mean ◽

Molecular Aspects ◽

The One ◽

Post Hoc ◽

Old Mice ◽

Experimental Group

Background: The purpose of this study was to determine the effects of alginate hydrogel as a capsule to protect the ovary against possible detrimental effects of vitrification and warming on morphology and expression of apoptosis-related genes in the mouse ovary. Methods: In this experimental study, the ovaries from twenty-five female 8-week-old mice were divided into five groups of non-vitrified ovaries, vitrified ovaries, ovaries that were encapsulated with concentrations of 0.5, 0.75 and 1% of alginate hydrogel. The morphological study was performed using hematoxylin and eosin staining. Expression levels of apoptosis-associated genes were quantified in each group by real-time RT-PCR. The one-way ANOVA and post hoc test were used to analyze the data and values of p<0.05 were considered statistically significant. Results: The results of follicle count showed that the mean of total follicles in all groups was not significantly different. The average number of atretic follicles in vitrified and experimental groups significantly increased in comparison with the non-vitrified group (p=0.001). The results of the evaluation of apoptosis-related genes showed that the ratio of BAX/BCL-2 in experimental groups 1 and 2 was significantly higher than the vitrified group and experimental group 3 (p=0.000). The expression level of caspase 3 gene was not significantly different among all groups. Conclusion: Ovarian encapsulation with used concentrations of alginate hydrogel failed to improve the morphology and molecular aspects of follicles and it was not able to better preserve the intact follicles of vitrified ovaries. However, morphological and molecular findings appear to improve with increasing alginate hydrogel concentration.

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