Maximum Number Of Repetitions Research Articles

Efeito agudo do intervalo passivo e do alongamento no desempenho de séries múltiplas

The objective of this study was to determine the acute effect of passive rest intervals and static stretching between resistance exercise sets on the number of maximal repetitions (RM), rating of perceived exertion (RPE), and cumulative number of repetitions in multiple sets with a workload adjusted by the 8RM test. Fourteen trained male subjects (24.4 ± 2.1 years; 79.1 ± 7.1 kg; 175.4 ± 5.6 cm) were studied. On the first two visits, the subjects were submitted to the test and 8RM re-test using chest press (CP) and squat (SQ) exercises. On the two subsequent visits, all subjects were randomly assigned to two experimental situations: a) 8RM test with a passive rest interval (PI); b) 8RM test with static stretching (SS). The subjects performed three sets of CP and SQ, intercalated with 2 minutes of passive rest or 30 seconds of static stretching. ANOVA revealed a significant decrease (p < 0.05) in the second (PI = 6 ± 0.8 x SS = 5.2 ± 1.0 repetitions) and third (PI = 4.1 ± 0.8 X SS = 3.3 ± 0.6 repetitions) sets for CP and only in the third set (PI = 4.9 ± 0.8 X SS = 4.2 ± 1.0 repetitions) for SQ. For RPE, the Wilcoxon test showed significant differences (p < 0.05) between all sets for CP and SQ. For the cumulative number of repetitions, the paired t-test revealed a significant decrease (p < 0.05) for CP (PI = 18.3 ± 1.5 X SS = 16.8 ± 1.6 repetitions). These results indicate that static stretching between resistance exercise sets decreases 8RM test performance.

Acute effect of passive rest intervals and stretching exercise on multiple set performance

The objective of this study was to determine the acute effect of passive rest intervals and static stretching between resistance exercise sets on the number of maximal repetitions (RM), rating of perceived exertion (RPE), and cumulative number of repetitions in multiple sets with a workload adjusted by the 8RM test. Fourteen trained male subjects (24.4 ± 2.1 years; 79.1 ± 7.1 kg; 175.4 ± 5.6 cm) were studied. On the first two visits, the subjects were submitted to the test and 8RM re-test using chest press (CP) and squat (SQ) exercises. On the two subsequent visits, all subjects were randomly assigned to two experimental situations: a) 8RM test with a passive rest interval (PI); b) 8RM test with static stretching (SS). The subjects performed three sets of CP and SQ, intercalated with 2 minutes of passive rest or 30 seconds of static stretching. ANOVA revealed a significant decrease (p < 0.05) in the second (PI = 6 ± 0.8 x SS = 5.2 ± 1.0 repetitions) and third (PI = 4.1 ± 0.8 X SS = 3.3 ± 0.6 repetitions) sets for CP and only in the third set (PI = 4.9 ± 0.8 X SS = 4.2 ± 1.0 repetitions) for SQ. For RPE, the Wilcoxon test showed significant differences (p < 0.05) between all sets for CP and SQ. For the cumulative number of repetitions, the paired t-test revealed a significant decrease (p < 0.05) for CP (PI = 18.3 ± 1.5 X SS = 16.8 ± 1.6 repetitions). These results indicate that static stretching between resistance exercise sets decreases 8RM test performance.

Vertical whole-body vibrations improve the total volume of a biceps curl set to failure

The purpose of this study was to examine the acute effects of using whole-body vibrations exposure during a biceps curl set to failure (70% one-repetition maximum load) on number of repetitions performed, perceived exertion, as well as velocity- and acceleration-related parameters. Twenty-three recreationally active students (19 males and 4 females) completed one set of the biceps curl exercise with and without vibration applied. Results indicate that the vibration platform provides additional stimulus for biceps curl performance, enhancing the number of maximal repetitions achieved throughout a set to volitional exhaustion at 70% one-repetition maximum. These findings suggest that vibration can have a significant influence on exercise performance, even when the stimulus is not applied directly to the muscle group being stressed.

Influence of “In Series” Elastic Resistance on Muscular Performance During a Biceps-curl Set on the Cable Machine

This study aimed to investigate the role of elastic resistance (ER) applied "in series" to a pulley-cable (PC) machine on the number of repetitions performed, kinematics parameters, and perceived exertion during a biceps-curl set to failure with a submaximal load (70% of the 1 repetition maximum). Twenty-one undergraduate students (17 men and 4 women) performed, on 2 different days, 1 biceps-curl set on the PC machine. Subjects were randomly assigned to complete 2 experimental conditions in a cross-over fashion: conventional PC mode or ER + PC mode. Results indicate ER applied "in series" to a PC machine significantly reduces (p < 0.05) the maximal number of repetitions and results in a smooth and consistent decline in mean acceleration throughout the set, in comparison to the conventional PC mode. Although no significant differences were found concerning intrarepetition kinematics, the ER trended to reduce (18.6%) the peak acceleration of the load. With a more uniformly distributed external resistance, a greater average muscle tension could have been achieved throughout the range of movement, leading to greater fatigue that could explain the lower number of maximal repetitions achieved. The application of force in a smooth, consistent fashion during each repetition of an exercise, while avoiding active deceleration, is expected to enhance the benefits of the resistance exercise, especially for those seeking greater increases in muscular hypertrophy.

Analysis of Factors That Influence the Maximum Number of Repetitions in Two Upper-Body Resistance Exercises: Curl Biceps and Bench Press

The purpose of this study was to analyze the influence of exercise type, set configuration, and relative intensity load on relationship between 1 repetition maximum (1RM) and maximum number of repetitions (MNR). Thirteen male subjects, experienced in resistance training, were tested in bench press and biceps curl for 1RM, MNR at 90% of 1RM with cluster set configuration (rest of 30s between repetitions) and MNR at 70% of 1RM with traditional set configuration (no rest between repetitions). A lineal encoder was used for measuring displacement of load. Analysis of variance analysis revealed a significant effect of load (p<0.01) and a tendency in exercise factor (p=0.096), whereas the interaction effect was not significant. MNR at 70% of 1RM was lower for biceps curl (16.31+/-2.59 vs. 8.77+/-3 in bench press and biceps curl, respectively; p<0.05) and at 90% of 1RM (21.85+/-11.06 vs. 18.54+/-12.84 in bench press and biceps curl, respectively; p>0.05). Correlation between 1RM and MNR was significant for medium-intensity in biceps curl (r=-0.574; p<0.05) and between MNR and 1RM/body mass (r=-0.574; p<0.05). Neither 1RM nor 1RM/body mass correlated with velocity along set, so velocity seems to be similar at a same relative intensity for subjects with differences in maximum strength levels. From our results, we suggest the employment of MNR rather than % of 1RM for training monitoring. Furthermore, we suggest the introduction of cluster set configuration for upper-body assessment of MNR and for upper-body muscular endurance training at high-intensity loads, as it seems an efficient approach in looking for sessions with greater training volumes. This could be an interesting approach for such sports as wrestling or weightlifting.

Benefits of Motor Imagery Training on Muscle Strength

It is well established that motor imagery (MI) improves motor performance and motor learning efficiently. Previous studies provided evidence that muscle strength may benefit from MI training, mainly when movements are under the control of large cortical areas in the primary motor cortex. The purpose of this experiment is to assess whether MI might improve upper and lower limbs' strength through an ecological approach and validation, with complex and multijoint exercises. Nine participants were included in the MI group and 10 in the control (CTRL) group. The 2 groups performed identical bench press and leg press exercises. The MI group was instructed to visualize and feel the correspondent contractions during the rest period, whereas the CTRL group carried out a neutral task. The maximal voluntary contraction (MVC) and the maximal number of repetitions (MR) using 80% of the pre-test MVC weight were measured. Although both MI and CTRL groups enhanced their strength through the training sessions, the leg press MVC was significantly higher in the MI group than in the CTRL group (p<0.05). The interaction between the leg press MR and the group was marginally significant (p=0.076). However, we did not find any difference between the MI and CTRL groups, both in the bench press MVC and MR. MI-related training may contribute to the improvement of lower limbs performance by enhancing the technical execution of the movement, and the individual intrinsic motivation. From an applied and practical perspective, we state that athletes may perform imagined muscles contractions, most especially during the rest periods of their physical training, to contribute to the enhancement of concentric strength.

The Acute Effects of Arginine Supplementation on Vasodilatation, Nitric Oxide Production and Muscle Performance

Nutritional supplements based on the amino acid arginine (Arg) have been used mainly by recreational resistance exercise trained subjects, under the claim that improvements will occur in muscle performance due to an increase on nitric oxide (NO) and on blood flow to muscles in exercise. However, NO supplementations studies have demonstrated controversial results in literature. PURPOSE: To evaluate the effects of supplementation with Arg on vasodilatation, NO production, and muscle performance in recreational resistance exercise (RE) trained man. METHODS: Sixteen subjects (18 - 29 years), randomly assign to 4 days of oral supplementation (3.2 - 9.6 g/day) of Arg or placebo (Pla) in a double blind crossover design, with washout of 2 weeks between phases. They were submitted to 3 sets of biceps curl with 65% of 1RM (maximum repetition) when blood lactate (LAC) and vascular parameters were measured by EcoDoppler on the right bracquial artery (arterial diameter - mean of longitudinal and transversal measures - AD, velocity time integral - VTI, peak systolic ventricular - PSV, vascular resistance - RI, systolic flow index - SFI), at rest, after occlusion, post-exercise biceps curl (1, 5 and 10 min). NO production was estimated by nitrite serum post exercise. The muscular performance and fatigue ratio were measured by the maximum number of repetitions in the 3 bout of exercise. RESULTS: Almost all vascular parameters (DA, PSV, VTI, SFI, RI) and LAC differed from the rest of other periods for both groups (P<0.05), although the SFI and RI did not differ from rest to post-occlusion on Pla and Arg group, respectively. The ANOVA with repeated measures showed no significant differences between Arg and Pla groups when compared the mean vascular parameters registered, except for AD on post-exercise 1 min (AD: PLA= 0.434 ± 0.035; Arg= 0.446 ± 0.036; p= 0.023). No effect of Arg was found in muscle performance from number of exercise repetitions, or LAC and NO production. The short period supplementation of oral Arg does not result in vascular changes, improvement in RE muscle performance, or increased production of NO. CONCLUSIONS: Although long-term studies are needed to better elucidate these mechanisms, our findings suggest no ergogenic effects of Arg supplementation in recreational resistance exercise trained men.

Local Muscular Endurance and Prediction of 1 Repetition Maximum for Bench In 4 Athletic Populations

The aim of this study was to determine a predictive equation of 1 repetition maximum (1RM) from local muscular endurance. Different athletic male populations were assessed: racket/ball games players (n = 31), power lifters (n = 22), swimmers (n = 28), and rowers (n = 29). After the 1RM assessment for the bench press, the maximum number of repetitions (MNR) relative to the 1RM (85%, 75%, 60%, 40%, and 20%) was tested. No significant differences in strength evolution from 20% to 100% of the 1RM was found between power lifters and racket/ball games players and between swimmers and rowers. However, differences in the strength evolution appeared between these 2 mixed groups (p < 0.01), with differences appearing from 75% of 1RM to lesser relative strength (p < 0.05). Nonlinear equations fitted best with the actual data for the capacity to repeat lifts. The evolution of strength from 100% to 20% of 1RM was better described when the groups' specific equations were used as demonstrated by r, and residuals range between the predicted minus the measured 1RM. The strength endurance competences for high loads (100%-75%) were adequately modelled by the equation based on the total population. The accuracy of the 1RM prediction was better when a reduced number of lifts was performed. For untrained or novice subjects, the use of group-specific equations for the all evolutionary profile of strength allows a good estimate of 1RM and provides adequate numbers of lifts for all levels of strength, thus optimizing the training programs.

서키트 웨이트 트레이닝이 과체중 남자대학생의 혈중 ghrelin 및 peptide-YY 농도에 미치는 영향

This study investigated the effect of 8-weeks circuit weight training(CWT) on fasting levels of ghrelin, peptide YY(PYY) in overweight(BMI23) college students. Resistance training consisted of three sets of circuit weight training for 8-10 stations and at an intensity corresponding to 40-60% of one-repetition maximum. The maximum number of repetitions in each station was 15. Body composition, plasma ghrelin, PYY, leptin, and insulin were measured at before, and after CWT. Subjects were divided control group(CON, lost less than 5% of body weight, n=10) and weight loss group(WL, lost more than 5% of body weight, n=8) after completion of CWT. The statistical analysis was evaluated by ANOVA for repeated measures. CWT caused significant decrease of body weight, fat, leptin, insulin and increase of ghrelin, but PYY decrease was not significant. Body weight and body fat loss in WL was greater than CON, but hormone changes were not affected with weight loss. CWT increased circulating ghrelin, an orexigenic factor, but moderate(5%) weigh loss was not altered physiological appetite biomarkers.

Influência da ordem dos exercícios sobre o número de repetições e percepção subjetiva do esforço em mulheres jovens e idosas

Estudos sobre a influência da ordem de execução dos exercícios no desempenho da força em idosos são escassos. O objetivo do presente estudo foi comparar a influência da ordem de execução dos exercícios sobre o número de repetições e percepção de esforço de oito idosas (69 ± 7 anos) e 12 jovens (22 ± 2 anos) praticantes de treinamento resistido. As voluntárias executaram sessões com três séries até a exaustão com cargas estabelecidas em 10 repetições máximas (RM), em sequências invertidas de exercícios: sequência A - supino horizontal (SH), desenvolvimento em pé (DP) e rosca tríceps no pulley baixo (TP); sequência B - TP, DP e SH. A ANOVA de duas entradas com medidas repetidas revelou que o número de repetições no grupo de jovens foi sempre menor no último exercício, independentemente da sequência ou grupamento muscular envolvido (p &lt; 0,05). O número de repetições permaneceu estável na sequência A para grupo de idosas, mas declinou significativamente na sequência B (p &lt; 0,05). Não houve diferenças para a percepção de esforço ao final das sequências no grupo de jovens, mas no grupo de idosas a PSE foi significativamente maior em na sequência B (p &lt; 0,05). Conclui-se que a ordem dos exercícios foi indiferente para o desempenho do grupo jovem, mas influenciou o número máximo de repetições em cada exercício e a percepção de esforço ao final das sequências no grupo de idosas.

Gender differences and reliability of selected physical performance tests in young women and men

Although push-ups and sit-ups are among the most commonly used body-weight exercises to improve and assess strength and fitness, there is a lack of reproducible test protocols in the scientific literature. The aim of this study was to evaluate the test–retest reliability of sit-ups and push-ups and to determine performance differences in muscular endurance (maximal number of repetitions) and power (timed, maximal number of repetitions in 30 s) in young women and men. Thirty-eight women and 25 men, 18–35 years of age, participated in the study. Thirteen women participants performed two test sessions of each test using a test–retest design. A high reliability was noted for both the sit-up and the push-ups tests (intraclass correlation values ranged from 0.92 to 0.95). There were no significant differences between the men and the women in the mean number of sit-ups (42 and 41 repetitions respectively for endurance and 16 and 14 repetitions respectively for power), whereas the men performed significantly more...

Acute Effects of Different Stretching Exercises on Muscular Endurance

This study aims to evaluate the acute effects of different stretching exercises on muscular endurance in men, in terms of the number of sets, set duration, and type of stretching. Two experiments were conducted; in the first one (E1), the subjects (n = 19) were evaluated to test the effect on the number of sets, and, in the second one (E2), the subjects (n = 15) were tested for the effect of set duration and type of stretching. After a warm-up of 10-15 repetitions of a bench press (BP) with submaximal effort, a one-repetition maximum (1RM) test was applied. For E1, BP endurance was evaluated after static stretching comprising one set of 20 seconds (1 x 20), two sets of 20 seconds (2 x 20), and three sets of 20 seconds (3 x 20). For E2, BP endurance was evaluated after static stretching comprising one set of 20 seconds (1 x 20), one set of 40 seconds (1 x 40), and proprioceptive neuromuscular facilitation (PNF) stretching. All tests were performed 48-72 hours apart, at which time the muscular endurance was assessed through the maximal number of repetitions (NR) of BP at 85% of 1RM until fatigue. The NR and the overload volume (OV) were compared among tests through repeated-measures analysis of variance. No significant effect of the number of sets on muscular endurance was observed because no statistically significant difference was found when comparing all stretching exercises of E1 in terms of NS (p = 0.5377) and OV (p = 0.5723). However, significant reductions were obtained in the set duration and PNF on NR (p < 0.0001) and OV (p < 0.0001), as observed in E2. The results suggest that a stretching protocol can influence BP endurance, whereas a decrease in endurance is suggested to be attributable to set duration and PNF. On the other hand, a low volume of static stretching does not seem to have a significant effect on muscular endurance.

How many runs can a string contain?

Given a string x = x [ 1 . . n ] , a repetition of period p in x is a substring u r = x [ i + 1 . . i + r p ] , p = ∣ u ∣ , r ≥ 2 , where neither u = x [ i + 1 . . i + p ] nor x [ i + 1 . . i + ( r + 1 ) p + 1 ] is a repetition. The maximum number of repetitions in any string x is well known to be Θ ( n log n ) . A run or maximal periodicity of period p in x is a substring u r t = x [ i + 1 . . i + r p + ∣ t ∣ ] of x , where u r is a repetition, t a proper prefix of u , and no repetition of period p begins at position i of x or ends at position i + r p + ∣ t ∣ + 1 . In 2000 Kolpakov and Kucherov showed that the maximum number ρ ( n ) of runs in any string x [ 1 . . n ] is O ( n ) , but their proof was nonconstructive and provided no specific constant of proportionality. At the same time, they presented experimental data to prompt the conjecture: ρ ( n ) < n . Recently, Rytter [Wojciech Rytter, The number of runs in a string: Improved analysis of the linear upper bound, in: B. Durand, W. Thomas (Eds.), STACS 2006, in: Lecture Notes in Computer Science, vol. 3884, Springer-Verlag, Berlin, 2006, pp. 184–195] made a significant step toward proving this conjecture by showing that ρ ( n ) < 5 n . In this paper we improve Rytter’s approach and press the bound on ρ ( n ) further, proving ρ ( n ) ≤ 3.48 n .

Influência aguda da ordem dos exercícios resistidos em uma sessão de treinamento para peitorais e tríceps

This experiment investigated the Influence of different resistance exercise order in a training session for chest and triceps on the number of maximum repetitions (RM). Thirteen trained men participated in the experiment (23.8±2.5 years; 76.5±12 kg; 178.5±6.3 cm). Data were collected in two phases: (a) determination of a 8RM load in the: bench press (BP), incline bench press (IBP), decline press (DP), triceps pushdown (TP) and triceps extension (TE), and (b) execution of 3 sets with loads for 8RM, three minutes of interval between sets, five minutes among exercises, in two sequences, to know: (SEQ1); BP, IBP, DP, TP, and TE (SEQ2) TE, TP, DP, IBP, and BP. The paired test t was used to verify the difference between the total numbers of RM produced between sequences. ANOVA two-way was used to verify the differences in the number of RM in each exercise among the sequences. ANOVA one-way to compare the number of RM for set inside the sequences. To identify these differences the post hoc of Tukey was used. Level significance adopted p<0.05. The total number of RM didn’t present significant differences among the sequences. The average number of RM for exercise was smaller when the same was accomplished in the end of the sequence.

Influência aguda da ordem dos exercícios resistidos em uma sessão de treinamento para peitorais e tríceps

This experiment investigated the Influence of different resistance exercise order in a training session for chest and triceps on the number of maximum repetitions (RM). Thirteen trained men participated in the experiment (23.8±2.5 years; 76.5±12 kg; 178.5±6.3 cm). Data were collected in two phases: (a) determination of a 8RM load in the: bench press (BP), incline bench press (IBP), decline press (DP), triceps pushdown (TP) and triceps extension (TE), and (b) execution of 3 sets with loads for 8RM, three minutes of interval between sets, five minutes among exercises, in two sequences, to know: (SEQ1); BP, IBP, DP, TP, and TE (SEQ2) TE, TP, DP, IBP, and BP. The paired test t was used to verify the difference between the total numbers of RM produced between sequences. ANOVA two-way was used to verify the differences in the number of RM in each exercise among the sequences. ANOVA one-way to compare the number of RM for set inside the sequences. To identify these differences the post hoc of Tukey was used. Level significance adopted p<0.05. The total number of RM didn’t present significant differences among the sequences. The average number of RM for exercise was smaller when the same was accomplished in the end of the sequence.

EFFECTS OF SHORT VS. LONG REST PERIOD BETWEEN SETS ON ELBOW-FLEXOR MUSCULAR ENDURANCE DURING RESISTANCE TRAINING TO FAILURE

This study aimed to examine short- term resistance training effects of resting period length between sets on maximal number of repetitions and mean velocity over a moderate-intensity (60% of the maximum voluntary isometric contraction [MVIC]) set to failure on elbow-flexor muscles. The MVIC and surface electromyographic activity (sEMG) were also measured. Twenty-one untrained subjects were divided into 3 groups: short rest between sets (1 minute; SR), long rest between sets (4 minutes; LR), and nontraining control group (CG). The SR and LR performed 3 sets to failure in an arm-curl machine, 2 days per week for 5 weeks, with moderate loads (60–75% of the MVIC). The LR completed a significantly higher (31.6%, p < 0.05) total training volume than the SR. Both training groups enhanced the maximal number of repetitions to failure, with no significant differences in the magnitude of gains. The posttraining average velocity achieved by the SR at 40, 50, 60, 70, 80, and 90% of the total number of repetitions completed was significantly higher (p < 0.05) than the corresponding average velocity achieved on pretraining conditions, whereas no significant differences were observed in the LR. No significant changes in the MVIC or sEMG were observed in any group. We conclude that short-term elbow-flexor resistance training to failure, allowing 1 or 4 minutes of rest between sets, induces similar gains concerning local muscular endurance. Nevertheless, only the SR training approach reduced the rate of decline in the average repetition velocity during a set to failure. This can be of some importance in sport modalities in which not only the maximal number of repetitions (e.g., muscle endurance), but also a greater maintenance of high repetition velocities, may be critical for performance.

Effect of Red Bull Energy Drink on Repeated Wingate Cycle Performance and Bench-Press Muscle Endurance

The purpose of this study was to determine the effects of Red Bull energy drink on Wingate cycle performance and muscle endurance. Healthy young adults (N = 15, 11 men, 4 women, 21 +/- 5 y old) participated in a crossover study in which they were randomized to supplement with Red Bull (2 mg/kg body mass of caffeine) or isoenergetic, isovolumetric, noncaffeinated placebo, separated by 7 d. Muscle endurance (bench press) was assessed by the maximum number of repetitions over 3 sets (separated by 1-min rest intervals) at an intensity corresponding to 70% of baseline 1-repetition maximum. Three 30-s Wingate cycling tests (load = 0.075 kp/kg body mass), with 2 min recovery between tests, were used to assess peak and average power output. Red Bull energy drink significantly increased total bench-press repetitions over 3 sets (Red Bull = 34 +/- 9 vs. placebo = 32 +/- 8, P %%%lt; 0.05) but had no effect on Wingate peak or average power (Red Bull = 701 +/- 124 W vs. placebo = 700 +/- 132 W, Red Bull = 479 +/- 74 W vs. placebo = 471 +/- 74 W, respectively). Red Bull energy drink significantly increased upper body muscle endurance but had no effect on anaerobic peak or average power during repeated Wingate cycling tests in young healthy adults.

Maximal repetitions in strings

The cornerstone of any algorithm computing all repetitions in strings of length n in O ( n ) time is the fact that the number of maximal repetitions (runs) is linear. Therefore, the most important part of the analysis of the running time of such algorithms is counting the number of runs. Kolpakov and Kucherov [R. Kolpakov, G. Kucherov, Finding maximal repetitions in a word in linear time, in: Proc. of FOCS'99, IEEE Computer Society Press, 1999, pp. 596–604] proved it to be cn but could not provide any value for c. Recently, Rytter [W. Rytter, The number of runs in a string: Improved analysis of the linear upper bound, in: B. Durand, W. Thomas (Eds.), Proc. of STACS'06, in: Lecture Notes in Comput. Sci., vol. 3884, Springer, Berlin, Heidelberg, 2006, pp. 184–195] proved that c ⩽ 5 . His analysis has been improved by Puglisi et al. to obtain 3.48 and by Rytter to 3.44 (both submitted). The conjecture of Kolpakov and Kucherov, supported by computations, is that c = 1 . Here we improve dramatically the previous results by proving that c ⩽ 1.6 and show how it could be improved by computer verification down to 1.18 or less. While the conjecture may be very difficult to prove, we believe that our work provides a good approximation for all practical purposes. For the stronger result concerning the linearity of the sum of exponents, we give the first explicit bound: 5.6 n. Kolpakov and Kucherov did not have any and Rytter considered “unsatisfactory” the bound that could be deduced from his proof. Our bound could be as well improved by computer verification down to 2.9 n or less.

Effect of Caffeinated Energy Drink on Muscle Endurance and Wingate Cycle Performance in Young Adults

Caffeinated energy drinks have gained popularity in recent years. Caffeine has been shown to increase short-term muscle endurance and power output. PURPOSE: To determine the effects of a caffeinated energy drink on upper body muscle endurance and repeated Wingate cycle performance in young males and females. METHODS: Healthy young adults (n=15, 11 male, 4 female, ∼21yrs) participated in a cross-over design where they were randomized to supplement with a caffeinated energy drink (2mg/kg body mass caffeine) or isoenergetic, isovolumetric, non-caffeinated placebo, separated by ∼7 days. Muscular endurance (bench press) was assessed by the maximum number of repetitions over 3 sets (separated by 1-min rest intervals) at an intensity corresponding to 70% baseline 1-repetition maximum (1-RM). Three 30s Wingate cycling tests (load=0.075kp/kg body mass), with 2 minutes recovery between each, were used to assess peak power and average power output. RESULTS: The caffeinated energy drink significantly increased total bench press repetitions over 3 sets (caffeine= 34±9 vs. placebo = 32±8; p<0.05), with no greater effect on peak or average power (caffeine=701±124W vs. placebo=700±132W; caffeine=479±74Wvs. placebo=471±74W). CONCLUSION: The caffeine containing energy drink significantly increased upper body muscle endurance, but had no effect on anaerobic peak or average power in young healthy adults. Supported by Red Bull Canada.

Effects of Short vs. Long Rest Period Between Sets on Elbow-Flexor Muscular Endurance During Resistance Trainingto Failure

This study aimed to examine short-term resistance training effects of resting period length between sets on maximal number of repetitions and mean velocity over a moderate-intensity (60% of the maximum voluntary isometric contraction [MVIC]) set to failure on elbow-flexor muscles. The MVIC and surface electromyographic activity (sEMG) were also measured. Twenty-one untrained subjects were divided into 3 groups: short rest between sets (1 minute; SR), long rest between sets (4 minutes; LR), and nontraining control group (CG). The SR and LR performed 3 sets to failure in an arm-curl machine, 2 days per week for 5 weeks, with moderate loads (60-75% of the MVIC). The LR completed a significantly higher (31.6%, p < 0.05) total training volume than the SR. Both training groups enhanced the maximal number of repetitions to failure, with no significant differences in the magnitude of gains. The posttraining average velocity achieved by the SR at 40, 50, 60, 70, 80, and 90% of the total number of repetitions completed was significantly higher (p < 0.05) than the corresponding average velocity achieved on pretraining conditions, whereas no significant differences were observed in the LR. No significant changes in the MVIC or sEMG were observed in any group. We conclude that short-term elbow-flexor resistance training to failure, allowing 1 or 4 minutes of rest between sets, induces similar gains concerning local muscular endurance. Nevertheless, only the SR training approach reduced the rate of decline in the average repetition velocity during a set to failure. This can be of some importance in sport modalities in which not only the maximal number of repetitions (e.g., muscle endurance), but also a greater maintenance of high repetition velocities, may be critical for performance.