Submit
Browse All

The Journal of Visualized Experiments (JoVE) is a peer reviewed, PubMed-indexed video journal. Our mission is to increase the productivity of scientific research.

Recommend to Librarian

In JoVE (1)

Other Publications (32)

Articles by Carlos Ugrinowitsch in JoVE

 JoVE Clinical and Translational Medicine

Vascular Occlusion Training for Inclusion Body Myositis: A Novel Therapeutic Approach


JoVE 1894 6/05/2010

1,2, 1, 2, 2, 2, 1, 1, 1, 1,2

1School of Physical Education and Sport, University of São Paulo, 2Division of Rheumatology, School of Medicine, University of São Paulo

The present article presents the details pertaining to the application of resistance training associated to vascular occlusion in IBM patients.

Other articles by Carlos Ugrinowitsch on PubMed

Limitations of Ordinary Least Squares Models in Analyzing Repeated Measures Data

Medicine and Science in Sports and Exercise. Dec, 2004  |  Pubmed ID: 15570152

To a) introduce and present the advantages of linear mixed models using generalized least squares (GLS) when analyzing repeated measures data; and b) show how model misspecification and an inappropriate analysis using repeated measures ANOVA with ordinary least squares (OLS) methodology can negatively impact the probability of occurrence of Type I error.

Short-term Effects on Lower-body Functional Power Development: Weightlifting Vs. Vertical Jump Training Programs

Journal of Strength and Conditioning Research / National Strength & Conditioning Association. May, 2005  |  Pubmed ID: 15903387

Among sport conditioning coaches, there is considerable discussion regarding the efficiency of training methods that improve lower-body power. Heavy resistance training combined with vertical jump (VJ) training is a well-established training method; however, there is a lack of information about its combination with Olympic weightlifting (WL) exercises. Therefore, the purpose of this study was to compare the short-term effects of heavy resistance training combined with either the VJ or WL program. Thirty-two young men were assigned to 3 groups: WL = 12, VJ = 12, and control = 8. These 32 men participated in an 8-week training study. The WL training program consisted of 3 x 6RM high pull, 4 x 4RM power clean, and 4 x 4RM clean and jerk. The VJ training program consisted of 6 x 4 double-leg hurdle hops, 4 x 4 alternated single-leg hurdle hops, 4 x 4 single-leg hurdle hops, and 4 x 4 40-cm drop jumps. Additionally, both groups performed 4 x 6RM half-squat exercises. Training volume was increased after 4 weeks. Pretesting and posttesting consisted of squat jump (SJ) and countermovement jump (CMJ) tests, 10- and 30-m sprint speeds, an agility test, a half-squat 1RM, and a clean-and-jerk 1RM (only for WL). The WL program significantly increased the 10-m sprint speed (p < 0.05). Both groups, WL and VJ, increased CMJ (p < 0.05), but groups using the WL program increased more than those using the VJ program. On the other hand, the group using the VJ program increased its 1RM half-squat strength more than the WL group (47.8 and 43.7%, respectively). Only the WL group improved in the SJ (9.5%). There were no significant changes in the control group. In conclusion, Olympic WL exercises seemed to produce broader performance improvements than VJ exercises in physically active subjects.

Influence of Training Background on Jumping Height

Journal of Strength and Conditioning Research / National Strength & Conditioning Association. Aug, 2007  |  Pubmed ID: 17685694

The aim of this study was to compare the pattern of force production and center of mass kinematics in maximal vertical jump performance between power athletes, recreational bodybuilders, and physically active subjects. Twenty-seven healthy male subjects (age: 24.5 +/- 4.3 years, height: 178.7 +/- 15.2 cm, and weight: 81.9 +/- 12.7 kg) with distinct training backgrounds were divided into 3 groups: power track athletes (PT, n = 10) with international experience, recreational bodybuilders (BB, n = 7) with at least 2 years of training experience, and physically active subjects (PA, n = 10). Subjects performed a 1 repetition maximum (1RM) leg press test and 5 countermovement jumps with no instructions regarding jumping technique. The power-trained group jumped significantly higher (p < 0.05) than the BB and PA groups (0.40 +/- 0.05, 0.31 +/- 0.04, and 0.30 +/- 0.05, respectively). The difference in jumping height was not produced by higher rates of force development (RFD) and shorter center of mass (CM) displacement. Instead, the PT group had greater CM excursion (p < 0.05) than the other groups. The PT and BB groups had a high correlation between jumping height and 1RM test (r = 0.93 and r = 0.89, p < 0.05, respectively). In conclusion, maximum strength seems to be important for jumping height, but RFD does not seem relevant to achieve maximum jumping heights. High RFD jumps should be performed during training only when sport skills have a time constraint for force application.

Intermittent Exercise As a Conditioning Activity to Induce Postactivation Potentiation

Journal of Strength and Conditioning Research / National Strength & Conditioning Association. Aug, 2007  |  Pubmed ID: 17685706

Postactivation potentiation (PAP) is defined as a short-term increase in voluntary muscle activation following a previous conditioning activity (CA). Controversy about PAP is mostly attributed to the characteristics of the CA and the training status of the subjects. While some studies have found that PAP can be induced by series of 5-10 second maximal voluntary isometric contractions or near maximal dynamic contractions (e.g., 3-5 repetition maximum), others have failed to do so. On the other hand, some studies suggest that intermittent contractions can also induce PAP. However, even though PAP was observed, its duration was not taken into account, leaving ground for further investigations. The purpose of this study was threefold: (a) to verify if PAP can progressively enhance performance of voluntary actions throughout a set of intermittent contractions; (b) to verify PAP duration when induced by an intermittent contractions protocol; and (c) to verify if PAP effects were reproducible in different sessions when induced by intermittent contractions. Ten physically active men, not engaged in strength training, underwent 5 randomized experimental sessions, during which they performed a set of 10 unilateral knee extensions (KE) (1 every 30 seconds) at 60 degrees x s(-1) in an isokinetic dynamometer. Peak torque was evaluated over the 10 unilateral KE and at the randomized intervals of 4, 6, 8, 10, and 12 minutes post CA. Peak torque was potentiated 1.3 (+/-0.79) N x m per unilateral KE, and the potentiation effect persisted for 12 minutes after the last contraction. These findings were reproduced in all 5 experimental sessions. Thus, intermittent conditioning activities seem to be an effective way to produce PAP. However, these activities should be tested in a more real world situation to verify the applicability as a warm-up routine.

Acute Effect of Two Aerobic Exercise Modes on Maximum Strength and Strength Endurance

Journal of Strength and Conditioning Research / National Strength & Conditioning Association. Nov, 2007  |  Pubmed ID: 18076237

The purpose of this study was to evaluate the effects of 2 modes of aerobic exercise (continuous or intermittent) on maximum strength (1 repetition maximum, 1RM) and strength endurance (maximum repetitions at 80% of 1RM) for lower- and upper-body exercises to test the acute hypothesis in concurrent training (CT) interference. Eight physically active men (age: 26.9 +/- 4.2 years; body mass: 82.1 +/- 7.5 kg; height: 178.9 +/- 6.0 cm) were submitted to: (a) a graded exercise test to determine V(.-)O2max (39.26 +/- 6.95 ml x kg(-1) x min(-1)) and anaerobic threshold velocity (3.5 mmol x L(-1)) (9.3 +/- 1.27 km x h(-1)); (b) strength tests in a rested state (control); and (c) 4 experimental sessions, at least 7 days apart. The experimental sessions consisted of a 5-kilometer run on a treadmill continuously (90% of the anaerobic threshold velocity) or intermittently (1:1 minute at V(.-)O2max). Ten minutes after the aerobic exercise, either a maximum strength or a strength endurance test was performed (leg press and bench press exercises). The order of aerobic and strength exercises followed a William's square distribution to avoid carryover effects. Results showed that only the intermittent aerobic exercise produced an acute interference effect on leg strength endurance, decreasing significantly (p < 0.05) the number of repetitions from 10.8 +/- 2.5 to 8.1 +/- 2.2. Maximum strength was not affected by the aerobic exercise mode. In conclusion, the acute interference hypothesis in concurrent training seems to occur when both aerobic and strength exercises produce significant peripheral fatigue in the same muscle group.

Effects of Creatine Supplementation on Renal Function: a Randomized, Double-blind, Placebo-controlled Clinical Trial

European Journal of Applied Physiology. May, 2008  |  Pubmed ID: 18188581

Creatine (CR) supplementation is commonly used by athletes. However, its effects on renal function remain controversial. The aim of this study was to evaluate the effects of creatine supplementation on renal function in healthy sedentary males (18-35 years old) submitted to exercise training. A randomized, double-blind, placebo-controlled trial was performed. Subjects (n = 18) were randomly allocated to receive treatment with either creatine (CR) ( approximately 10 g day(-1) over 3 months) or placebo (PL) (dextrose). All subjects undertook moderate intensity aerobic training, in three 40-min sessions per week, during 3 months. Serum creatinine, serum and urinary sodium and potassium were determined at baseline and at the end of the study. Cystatin C was assessed prior to training (PRE), after 4 (POST 4) and 12 weeks (POST 12). Cystatin C levels (mg L(-1)) (PRE CR: 0.82 +/- 0.09; PL: 0.88 +/- 0.07 vs. POST 12 CR: 0.71 +/- 0.06; PL: 0.75 +/- 0.09, P = 0.0001) were decreased over time, suggesting an increase in glomerular filtration rate. Serum creatinine decreased with training in PL but was unchanged with training in CR. No significant differences were observed within or between groups in other parameters investigated. The decrease in cystatin C indicates that high-dose creatine supplementation over 3 months does not provoke any renal dysfunction in healthy males undergoing aerobic training. In addition, the results suggest that moderate aerobic training per se may improve renal function.

Spinal Unloading After Abdominal Exercises

Clinical Biomechanics (Bristol, Avon). Jan, 2008  |  Pubmed ID: 17910988

Intervertebral discs are exposed to compressive forces, which produces fluid loss. This loss decreases disc height, spinal length and consequently overall stature. The loss of stature has been associated with spine loading and low back pain. Abdominal exercises increase intra-abdominal pressure and unload the spine. The purpose of this study was to identify if abdominal exercises may produce acute spinal unloading compared to a known unloading position.

The Influence of Resting Period Length on Jumping Performance

Journal of Strength and Conditioning Research / National Strength & Conditioning Association. Jul, 2008  |  Pubmed ID: 18545180

The purpose of this study was to determine a resting interval between countermovement jumps (i.e., volleyball spikes) that allows the maintenance of maximal jumping performance. Ten male volleyball players (1.85 +/- 0.05 m, 77.2 +/- 10.6 kg, 21.6 +/- 5.3 years) performed 6 experimental jumping sessions. In the first and sixth sessions, maximal countermovement jump height was measured, followed by submaximal countermovement jumps to the point of volitional fatigue. The number of countermovement jumps was used as a reference to test the effect of rest period between volleyball spikes. From the second to fifth experimental sessions, 30 maximal volleyball spikes were performed with different resting periods (i.e., 8, 14, 17, and 20 seconds) followed by countermovement jumps. Between the 15th and 30th spikes, the blood lactate concentration and heart rate were measured. Because the performance on the first and sixth sessions was the same, no training effects were noticed. During the 8-second resting interval set, the lactate concentration increased significantly between the 15th and 30th spikes (i.e., from 3.37 +/- 1.16 mmol to 4.94 +/- 1.49 mmol); the number of countermovement jumps decreased significantly after spikes compared to those performed without a previous effort (i.e., from 23 +/- 7 jumps to 17 +/- 9 jumps); and these variables were significantly correlated (r = -0.7). On the other hand, the lactate concentration and number of countermovement jumps were stable across the other resting intervals, without a heart rate steady state. The results indicate that an adequate resting period between spikes allowed participants to achieve a lactate steady state in which the performance was maintained during the exercise. These findings show that resting intervals between 14 and 17 seconds, typical during volleyball matches, are indicated to use in volleyball spike drills due to their capacity to maintain maximal jumping performance.

Does Creatine Supplementation Improve the Plasma Lipid Profile in Healthy Male Subjects Undergoing Aerobic Training?

Journal of the International Society of Sports Nutrition. 2008  |  Pubmed ID: 18831767

We aimed to investigate the effects of creatine (Cr) supplementation on the plasma lipid profile in sedentary male subjects undergoing aerobic training.

Acute Effect of a Ballistic and a Static Stretching Exercise Bout on Flexibility and Maximal Strength

Journal of Strength and Conditioning Research / National Strength & Conditioning Association. Jan, 2009  |  Pubmed ID: 19057408

Different stretching techniques have been used during warm-up routines. However, these routines may decrease force production. The purpose of this study was to compare the acute effect of a ballistic and a static stretching protocol on lower-limb maximal strength. Fourteen physically active women (169.3 +/- 8.2 cm; 64.9 +/- 5.9 kg; 23.1 +/- 3.6 years) performed three experimental sessions: a control session (estimation of 45 degrees leg press one-repetition maximum [1RM]), a ballistic session (20 minutes of ballistic stretch and 45 degrees leg press 1RM), and a static session (20 minutes of static stretch and 45 degrees leg press 1RM). Maximal strength decreased after static stretching (213.2 +/- 36.1 to 184.6 +/- 28.9 kg), but it was unaffected by ballistic stretching (208.4 +/- 34.8 kg). In addition, static stretching exercises produce a greater acute improvement in flexibility compared with ballistic stretching exercises. Consequently, static stretching may not be recommended before athletic events or physical activities that require high levels of force. On the other hand, ballistic stretching could be more appropriate because it seems less likely to decrease maximal strength.

Effect of Bench Press Exercise Intensity on Muscle Soreness and Inflammatory Mediators

Journal of Sports Sciences. Mar, 2009  |  Pubmed ID: 19253084

This study compared four different intensities of a bench press exercise for muscle soreness, creatine kinase activity, interleukin (IL)-1beta, IL-6, tumor necrosis factor-alpha (TNF-alpha), and prostaglandin E(2) (PGE(2)) concentrations in the blood. Thirty-five male Brazilian Army soldiers were randomly assigned to one of five groups: 50% one-repetition maximum (1-RM), 75% 1-RM, 90% 1-RM, 110% 1-RM, and a control group that did not perform the exercise. The total volume (sets x repetitions x load) of the exercise was matched among the exercise groups. Muscle soreness and plasma creatine kinase activity increased markedly (P < 0.05) after exercise, with no significant differences among the groups. Serum PGE(2) concentration also increased markedly (P < 0.05) after exercise, with a significantly (P < 0.05) greater increase in the 110% 1-RM group compared with the other groups. A weak but significant (P < 0.05) correlation was found between peak muscle soreness and peak PGE(2) concentration, but no significant correlation was evident between peak muscle soreness and peak creatine kinase activity, or peak creatine kinase activity and peak PGE(2) concentration. All groups showed no changes in IL-1beta, IL-6 or TNF-alpha. Our results suggest that the intensity of bench press exercise does not affect the magnitude of muscle soreness and blood markers of muscle damage and inflammation.

Nonlinear Periodization Maximizes Strength Gains in Split Resistance Training Routines

Journal of Strength and Conditioning Research / National Strength & Conditioning Association. Jul, 2009  |  Pubmed ID: 19528843

The purpose of our study was to compare strength gains after 12 weeks of nonperiodized (NP), linear periodized (LP), and nonlinear periodized (NLP) resistance training models using split training routines. Twenty-seven strength-trained men were recruited and randomly assigned to one of 3 balanced groups: NP, LP, and NLP. Strength gains in the leg press and in the bench press exercises were assessed. There were no differences between the training groups in the exercise pre-tests (p > 0.05) (i.e., bench press and leg press). The NLP group was the only group to significantly increase maximum strength in the bench press throughout the 12-week training period. In this group, upper-body strength increased significantly from pre-training to 4 weeks (p < 0.0001), from 4 to 8 weeks (p = 0.004), and from 8 weeks to the post-training (p < 0.02). The NLP group also exhibited an increase in leg press 1 repetition maximum at each time point (pre-training to 4 weeks, 4-8 week, and 8 weeks to post-training, p < 0.0001). The LP group demonstrated strength increases only after the eight training week (p = 0.02). There were no further strength increases from the 8-week to the post-training test. The NP group showed no strength increments after the 12-week training period. No differences were observed in the anthropometric profiles among the training models. In summary, our data suggest that NLP was more effective in increasing both upper- and lower-body strength for trained subjects using split routines.

Strength Training Improves Fall-related Gait Kinematics in the Elderly: a Randomized Controlled Trial

Clinical Biomechanics (Bristol, Avon). Dec, 2009  |  Pubmed ID: 19716637

Falls are one of the greatest concerns among the elderly. Among a number of strategies proposed to reduce the risk of falls, improving muscle strength has been applied as a successful preventive strategy. Although it has been suggested as a relevant strategy, no studies have analyzed how muscle strength improvements affect the gait pattern. The aim of this study was to determine the effects of a lower limb strength training program on gait kinematics parameters associated with the risk of falls in elderly women.

Hormonal Responses to Different Resistance Exercise Schemes of Similar Total Volume

Journal of Strength and Conditioning Research / National Strength & Conditioning Association. Oct, 2009  |  Pubmed ID: 19855324

This study assessed the effect of different resistance exercise scheme (RES) designs of similar total of load lifted on the responses of testosterone, cortisol, and creatine kinase (CK). Twenty-seven healthy males performed 1 of 4 bench press workouts described by the 1 repetition maximum (1RM) load: 4 sets of maximum repetitions at 50%-1RM (50%-1RM RES), 5 sets of maximum repetitions at 75%-1RM (75%-1RM RES), 10 sets of maximum repetitions at 90%-1RM (90%-1RM RES), or 8 sets of maximum repetitions at 110%-1RM (110%-1RM RES). Each RES was equated by the total volume of load lifted (repetitions x sets x load). Blood samples, collected pre-exercise (Pre) and post-exercise (Post) at 1 and 24 hours (24 h), were analyzed for total and free testosterone, total cortisol, and CK. In general, testosterone and cortisol showed little change within or between the different RES (p > 0.05), possibly because of the relatively low volume lifted and/or the small muscle mass activated by the bench press exercise. Cortisol was elevated after the 75%-1RM RES at the Post sample, with this response also exceeding the other RES (p < 0.05). The 24 h CK response was also elevated after the 75%-1RM RES (p < 0.05), thereby suggesting greater training strain for the same volume of load. These results confirm previous recommendations regarding the prescription of resistance exercise and the importance of total volume as a stimulus for activating the endocrine system and achieving long-term adaptation.

Transient Effects of Stretching Exercises on Gait Parameters of Elderly Women

Manual Therapy. Apr, 2009  |  Pubmed ID: 18314375

This study aimed to analyse the effects of a single stretching exercise session on a number of gait parameters in elderly participants in an attempt to determine whether these exercises can influence the risk of fall. Fifteen healthy women living in the community volunteered to participate in the study. A kinematic gait analysis was performed immediately before and after a session of static stretching exercises applied on hip flexor/extensor muscles. Results showed a significant influence of stretching exercises on a number of gait parameters, which have previously been proposed as fall predictors. Participants showed increased gait velocity, greater step length and reduced double support time during stance after performing stretching exercises, suggesting improved stability and mobility. Changes around the pelvis (increased anterior-posterior tilt and rotation range of motion) resulting from the stretching exercises were suggested to influence the gait parameters (velocity, step length and double support time). Therefore, stretching exercises were shown to be a promising strategy to facilitate changes in gait parameters related to the risk of fall. Some other gait variables related to the risk of fall remained unaltered (e.g., toe clearance). The stable pattern of segmental angular velocities was proposed to explain the stability of these unchanged gait variables. The results indicate that stretching exercises, performed on a regular (daily) basis, result in gait adaptations which can be considered as indicative of reduced fall risk. Other studies to determine whether regular stretching routines are an effective strategy to reduce the risk of fall are required.

Effects of Static Stretching on Energy Cost and Running Endurance Performance

Journal of Strength and Conditioning Research / National Strength & Conditioning Association. Sep, 2010  |  Pubmed ID: 19918196

Stretching before anaerobic events has resulted in declines in performance; however, the immediate effects of stretching on endurance performance have not been investigated. This study investigated the effects of static stretching on energy cost and endurance performance in trained male runners. Ten trained male distance runners aged 25 +/- 7 years with an average VO2max of 63.8 +/- 2.8 ml/kg/min were recruited. Participants reported to the laboratory on 3 separate days. On day 1, anthropometrics and VO2max were measured. On days 2 and 3, participants performed a 60-minute treadmill run randomly under stretching or nonstretching conditions separated by at least 1 week. Stretching consisted of 16 minutes of static stretching using 5 exercises for the major lower body muscle groups, whereas nonstretching consisted of 16 minutes of quiet sitting. The run consisted of a 30-minute 65% VO2max preload followed by a 30-minute performance run where participants ran as far as possible without viewing distance or speed. Total calories expended were determined for the 30-minute preload run, whereas performance was measured as distance covered in the performance run. Performance was significantly greater in the nonstretching (6.0 +/- 1.1 km) vs. the stretching (5.8 +/- 1.0 km) condition (p < 0.05), with significantly greater energy expenditure during the stretching compared with the nonstretching condition (425 +/- 50 vs. 405 +/- 50 kcals). Our findings suggest that stretching before an endurance event may lower endurance performance and increase the energy cost of running.

Resistance Training with Vascular Occlusion in Inclusion Body Myositis: a Case Study

Medicine and Science in Sports and Exercise. Feb, 2010  |  Pubmed ID: 19927034

Inclusion body myositis (IBM) is a rare idiopathic inflammatory myopathy that produces remarkable muscle weakness. Resistance training with vascular occlusion has been shown to improve muscle strength and cross-sectional area in other muscle wasting conditions.

Peak Torque and Rate of Torque Development in Elderly with and Without Fall History

Clinical Biomechanics (Bristol, Avon). Jun, 2010  |  Pubmed ID: 20350773

Falls are one of the greatest concerns among the elderly. A number of studies have described peak torque as one of the best fall-related predictor. No studies have comprehensively focused on the rate of torque development of the lower limb muscles among elderly fallers. Then, the aim of this study was to determine the relationship between muscle peak torque and rate of torque development of the lower limb joints in elderly with and without fall history. It was also aimed to determine whether these parameters of muscle performance (i.e., peak torque and rate of torque development) are related to the number of falls.

Effect of Eccentric Contraction Velocity on Muscle Damage in Repeated Bouts of Elbow Flexor Exercise

Applied Physiology, Nutrition, and Metabolism = Physiologie Appliquée, Nutrition Et Métabolisme. Aug, 2010  |  Pubmed ID: 20725121

Eccentric exercise induces muscle damage, but controversy exists concerning the effect of contraction velocity on the magnitude of muscle damage, and little is known about the effect of contraction velocity on the repeated-bout effect. This study examined slow (60 degrees.s(-1)) and fast (180 degrees.s(-1)) velocity eccentric exercises for changes in indirect markers of muscle damage following 3 exercise bouts that were performed every 2 weeks. Fifteen young men were divided into 2 groups based on the velocity of eccentric exercise: 7 in the Ecc60 (60 degrees.s(-1)) group, and 8 in the Ecc180 (180 degrees.s(-1)) group. The exercise consisted of 30 maximal eccentric contractions of the elbow flexors at each velocity, in which the elbow joint was forcibly extended from 60 degrees to 180 degrees (full extension) on an isokinetic dynamometer. Changes in maximal voluntary isometric contraction strength, range of motion, muscle soreness, and plasma creatine kinase activity before and for 4 days after the exercise were compared in the 2 groups using a mixed-model analysis (groupxboutxtime). No significant differences between groups were evident for changes in any variables following exercise bouts; however, the changes were significantly smaller (p<0.05) after the second and third bouts than after the first bout. These results indicate that the contraction velocity does not influence muscle damage or the repeated-bout effect.

Influence of High- and Low-carbohydrate Diet Following Glycogen-depleting Exercise on Heart Rate Variability and Plasma Catecholamines

Applied Physiology, Nutrition, and Metabolism = Physiologie Appliquée, Nutrition Et Métabolisme. Aug, 2010  |  Pubmed ID: 20725122

The purpose of this study was to investigate the effects of a short-term low- or high-carbohydrate (CHO) diet consumed after exercise on sympathetic nervous system activity. Twelve healthy males underwent a progressive incremental test; a control measurement of plasma catecholamines and heart rate variability (HRV); an exercise protocol to reduce endogenous CHO stores; a low- or high-CHO diet (counterbalanced order) consumed for 2 days, beginning immediately after the exercise protocol; and a second resting plasma catecholamine and HRV measurement. The exercise and diet protocols and the second round of measurements were performed again after a 1-week washout period. The mean (+/-SD) values of the standard deviation of R-R intervals were similar between conditions (control, 899.0+/-146.1 ms; low-CHO diet, 876.8+/-115.8 ms; and high-CHO diet, 878.7+/-127.7 ms). The absolute high- and low-frequency (HF and LF, respectively) densities of the HRV power spectrum were also not different between conditions. However, normalized HF and LF (i.e., relative to the total power spectrum) were lower and higher, respectively, in the low-CHO diet than in the control diet (mean+/-SD, 17+/-9 normalized units (NU) and 83+/-9 NU vs. 27+/-11 NU and 73+/-17 NU, respectively; p<0.05). The LF/HF ratio was higher with the low-CHO diet than with the control diet (mean+/-SD, 7.2+/-6.2 and 4.2+/-3.2, respectively; p<0.05). The mean values of plasma catecholamines were not different between diets. These results suggest that the autonomic control of the heart rate was modified after a short-term low-CHO diet, but plasma catecholamine levels were not altered.

The Influence of Familiarization Sessions on the Stability of Ramp and Ballistic Isometric Torque in Older Adults

Journal of Aging and Physical Activity. Oct, 2010  |  Pubmed ID: 20956841

Ramp isometric contractions determine peak torque (PT) and neuromuscular activation (NA), and ballistic contractions can be used to evaluate rate of torque development (RTD) and electrical mechanical delay (EMD). The purposes of this study were to assess the number of sessions required to stabilize ramp and ballistic PT and to compare PT and NA between contractions in older adults. Thirty-five older men and women (age 63.7 ± 3.7 yr, body mass 64.3 ± 10.7 kg, height 159.2 ± 6.6 cm) performed 4 sessions of unilateral ramp and ballistic isometric knee extension, 48 hr apart. PT significantly increased (main time effect p < .05) from the first to the third session, with no further improvements thereafter. There was a trend toward higher PT in ballistic than in ramp contractions. No difference between contraction types on EMG values was observed. Therefore, the authors suggest that 3 familiarization sessions be performed to correctly assess PT. In addition, PT, NA, RTD, and EMD can be assessed with ballistic contraction in older adults.

The Effect of Carbohydrate Mouth Rinse on Maximal Strength and Strength Endurance

European Journal of Applied Physiology. Sep, 2011  |  Pubmed ID: 21336838

It has been previously reported that carbohydrate (CHO) mouth rinse can improve exercise performance. The proposed mechanism involves increased activation of brain regions believed to be responsible for reward/motivation and motor control. Since strength-related performance is affected by central drive to the muscles, it seems reasonable to hypothesize that the positive CNS response to oral CHO sensing may counteract the inhibitory input from the muscle afferent pathways minimizing the drop in the central drive. The purpose of the current study was to test if CHO mouth rinse affects maximum strength and strength endurance performance. Twelve recreationally strength-trained healthy males (age 24.08 ± 2.99 years; height 178.09 ± 6.70 cm; weight 78.67 ± 8.17 kg) took part in the study. All of the tests were performed in the morning, after an 8 h overnight fasting. Subjects were submitted to a maximum strength test (1-RM) and a strength endurance test (six sets until failure at 70% of 1-RM), in separate days under three different experimental conditions (CHO mouth rinse, placebo-PLA mouth rinse and control-CON) in a randomized crossover design. The CHO mouth rinse (25 ml) occurred before every attempt in the 1-RM test, and before every set in the endurance strength test. Blood glucose and lactate were measured immediately before and 5 min post-tests. There were no significant differences in 1-RM between experimental conditions (CHO 101 ± 7.2 kg; PLA 101 ± 7.4 kg; CON 101 ± 7.2 kg; p = 0.98). Furthermore, there were no significance between trial differences in the number of repetitions performed in each set (p = 0.99) or the total exercise volume (number of repetitions × load lifted [kg]) (p = 0.98). A main effect for time (p < 0.0001) in blood lactate concentration was observed in both tests (1-RM and strength endurance). Blood glucose concentration did not differ between conditions. In conclusion, CHO mouth rinse does not affect maximum strength or strength endurance performance.

Effect of Different Resistance-training Regimens on the WNT-signaling Pathway

European Journal of Applied Physiology. Oct, 2011  |  Pubmed ID: 21365345

The purpose of the present study was to evaluate the effects of 8 weeks of strength and power training on the expression of genes related to the canonical WNT pathway and β-catenin protein levels in physically active men. Twenty-five subjects (27.4 ± 4.6 years) were balanced based on their relative maximum strength in the squat exercise (squat 1RM/body mass) and randomly assigned to strength training (ST) (n = 10), power training (PT) (n = 10), and control (C) (n = 5) groups. The ST and the PT groups performed high and low intensity squats, respectively, thrice a week, for 8 weeks. Muscle biopsies from the vastus lateralis muscle were collected before and after the training period. Relative strength and power increased similarly in both ST and PT groups (P < 0.001). Fiber cross-sectional area also increased similarly in both ST and PT groups. Gene expression and β-catenin protein expression levels were assessed by real-time PCR and Western blot. Certain genes were up-regulated in the ST group (WNT1: 6.4-fold, P < 0.0001; SFRP1: 3.3-fold, P < 0.0001 and LEF1: 7.3-fold, P < 0.0001) and also in the PT group (WNT1: 24.9-fold, P < 0.0001; SFRP1: 2.7-fold, P < 0.0001; LEF1: 34.1-fold, P < 0.0001 and Cyclin D1: 7.7-fold, P < 0.001). In addition, the expression of key WNT pathway genes was substantially more responsive to PT than to ST (WNT1: P < 0.0001; LEF1: P < 0.0001 and Cyclin D1: P < 0.001). Finally, the total β-catenin protein content increased only in the PT group (P < 0.05). Our data indicate that a PT regimen triggers greater responses in key elements of the WNT pathway.

Cardiopulmonary, Blood Metabolite and Rating of Perceived Exertion Responses to Constant Exercises Performed at Different Intensities Until Exhaustion

British Journal of Sports Medicine. Nov, 2011  |  Pubmed ID: 21464149

This study analysed cardiopulmonary, metabolic and rating of perceived exertion (RPE) responses during exercise bouts performed below, at and above the second lactate threshold (LT2) intensity.

Combination of General and Specific Warm-ups Improves Leg-press One Repetition Maximum Compared with Specific Warm-up in Trained Individuals

Journal of Strength and Conditioning Research / National Strength & Conditioning Association. Aug, 2011  |  Pubmed ID: 21544000

Accurate assessment of muscular strength is critical for exercise prescription and functional evaluation. The warm-up protocol may affect the precision of the 1 repetition maximum (1RM) test. Testing guidelines recommend performing both general and specific warm-ups before strength tests. The general warm-up intends to raise muscle temperature, whereas the specific warm-up aims to increase neuromuscular activation. Although there is scientific evidence for performing the specific warm-up, the effects of general warm-up on strength tests are still unclear. The purpose of this study was to investigate whether the combination of a general with a specific warm-up (G + SWU) protocol would improve leg press 1RM values compared with a specific warm-up (SWU) protocol. Thirteen participants were tested for leg-press 1RM under 2 warm-up conditions. In the first condition, participants performed the SWU only, which was composed of 1 set of 8 repetitions at approximately 50% of the estimated 1RM followed by another set of 3 repetitions at 70% of the estimated 1RM. In the second condition (G + SWU), participants performed the 1RM test after a 20-minute general warm-up on a stationary bicycle at 60% of HRmax and the same specific warm-up as in the SWU. Values of 1RM in SWU and in G + SWU were compared by a paired t-test, and significance level was set at p ≤ 0.05. Strength values were on average 8.4% (p = 0.002) higher in the G + SWU compared with the SWU. These results suggest that the G + SWU induced temperature-dependent neuromuscular adjustments that increased muscle force production capacity. Therefore, these results support the recommendations of the testing guidelines to perform a moderate intensity general warm-up in addition to the specific warm-up before maximum strength assessments.

The Rating of Perceived Exertion Predicts Intermittent Vertical Jump Demand and Performance

Journal of Sports Sciences. Jun, 2011  |  Pubmed ID: 21547835

The aims of this study were (a) to assess the ability of the rating of perceived exertion (RPE) to predict performance (i.e. number of vertical jumps performed to a fixed jump height) of an intermittent vertical jump exercise, and (b) to determine the ability of RPE to describe the physiological demand of such exercise. Eight healthy men performed intermittent vertical jumps with rest periods of 4, 5, and 6 s until fatigue. Heart rate and RPE were recorded every five jumps throughout the sessions. The number of vertical jumps performed was also recorded. Random coefficient growth curve analysis identified relationships between the number of vertical jumps and both RPE and heart rate for which there were similar slopes. In addition, there were no differences between individual slopes and the mean slope for either RPE or heart rate. Moreover, RPE and number of jumps were highly correlated throughout all sessions (r = 0.97-0.99; P < 0.001), as were RPE and heart rate (r = 0.93-0.97; P < 0.001). The findings suggest that RPE can both predict the performance of intermittent vertical jump exercise and describe the physiological demands of such exercise.

Salivary Hormone and Immune Responses to Three Resistance Exercise Schemes in Elite Female Athletes

Journal of Strength and Conditioning Research / National Strength & Conditioning Association. Aug, 2011  |  Pubmed ID: 21572351

This study examined the salivary hormone and immune responses of elite female athletes to 3 different resistance exercise schemes. Fourteen female basketball players each performed an endurance scheme (ES-4 sets of 12 reps, 60% of 1 repetition maximum (1RM) load, 1-minute rest periods), a strength-hypertrophy scheme (SHS-1 set of 5RM, 1 set of 4RM, 1 set of 3RM, 1 set of 2RM, and 1set of 1RM with 3-minute rest periods, followed by 3 sets of 10RM with 2-minute rest periods) and a power scheme (PS-3 sets of 10 reps, 50% 1RM load, 3-minute rest periods) using the same exercises (bench press, squat, and biceps curl). Saliva samples were collected at 07:30 hours, pre-exercise (Pre) at 09:30 hours, postexercise (Post), and at 17:30 hours. Matching samples were also taken on a nonexercising control day. The samples were analyzed for testosterone, cortisol (C), and immunoglobulin A concentrations. The total volume of load lifted differed among the 3 schemes (SHS > ES > PS, p < 0.05). Postexercise C concentrations increased after all schemes, compared to control values (p < 0.05). In the SHS, the postexercise C response was also greater than pre-exercise data (p < 0.05). The current findings confirm that high-volume resistance exercise schemes can stimulate greater C secretion because of higher metabolic demand. In terms of practical applications, acute changes in C may be used to evaluate the metabolic demands of different resistance exercise schemes, or as a tool for monitoring training strain.

Creatine but Not Betaine Supplementation Increases Muscle Phosphorylcreatine Content and Strength Performance

Amino Acids. Jul, 2011  |  Pubmed ID: 21744011

We aimed to investigate the role of betaine supplementation on muscle phosphorylcreatine (PCr) content and strength performance in untrained subjects. Additionally, we compared the ergogenic and physiological responses to betaine versus creatine supplementation. Finally, we also tested the possible additive effects of creatine and betaine supplementation. This was a double-blind, randomized, placebo-controlled study. Subjects were assigned to receive betaine (BET; 2 g/day), creatine (CR; 20 g/day), betaine plus creatine (BET + CR; 2 + 20 g/day, respectively) or placebo (PL). At baseline and after 10 days of supplementation, we assessed muscle strength and power, muscle PCr content, and body composition. The CR and BET + CR groups presented greater increase in muscle PCr content than PL (p = 0.004 and p = 0.006, respectively). PCr content was comparable between BET versus PL (p = 0.78) and CR versus BET + CR (p = 0.99). CR and BET + CR presented greater muscle power output than PL in the squat exercise following supplementation (p = 0.003 and p = 0.041, respectively). Similarly, bench press average power was significantly greater for the CR-supplemented groups. CR and BET + CR groups also showed significant pre- to post-test increase in 1-RM squat and bench press (CR: p = 0.027 and p < 0.0001; BET + CR: p = 0.03 and p < 0.0001 for upper- and lower-body assessments, respectively) No significant differences for 1-RM strength and power were observed between BET versus PL and CR versus BET + CR. Body composition did not differ between the groups. In conclusion, we reported that betaine supplementation does not augment muscle PCr content. Furthermore, we showed that betaine supplementation combined or not with creatine supplementation does not affect strength and power performance in untrained subjects.

Influence of Strength Training Background on Postactivation Potentiation Response

Journal of Strength and Conditioning Research / National Strength & Conditioning Association. Sep, 2011  |  Pubmed ID: 21747294

The aim of this study was to evaluate the influence of the subjects' level of maximal dynamic strength and training background on postactivation potentiation (PAP). A group of 23 subjects, composed of power track-and-field athletes (PT = 8), bodybuilders (BB = 7), and physically active subjects (PA = 8), participated in the study. Maximal dynamic strength (1 repetition maximum test) was assessed in the leg press exercise for subjects' characterization. Their countermovement vertical jump (CMJ) performance was assessed before and after 2 different conditioning activity (CA) protocols (1 or 3 maximum voluntary isometric contractions [MVICs] of 5-second duration in the leg press exercise) or after control (no CA), performed on separate days. No significant differences among groups were found for CMJ height or take-off velocity after any of the CA protocols (p ≤ 0.05). However, individual analysis showed that some subjects increased performance in response to the CA, despite their previous training history. We concluded that subjects' level of maximal dynamic strength and training background have no influence on PAP manifestation. Our data suggest that coaches should individually identify the athletes that are PAP responders before introducing MVICs as part of their warm-up routines.

Strength Training with Blood Flow Restriction Diminishes Myostatin Gene Expression

Medicine and Science in Sports and Exercise. Sep, 2011  |  Pubmed ID: 21900845

PURPOSE:: The aim of the study was to determine whether the similar muscle strength and hypertrophy responses observed after either low-intensity resistance exercise associated with moderate blood-flow restriction or high-intensity resistance exercise are associated with similar changes in mRNA expression of selected genes involved in the myostatin (MSTN) signaling. METHODS:: Twenty-nine physically active male subjects were divided into three groups: low-intensity (20% 1-RM) resistance training: LI (n = 10); low-intensity (20% 1-RM) resistance training associated with moderate blood-flow restriction: LIR (n = 10); and high-intensity (80% 1-RM) resistance training: HI (n = 9). All of the groups underwent an 8-week training program. Maximal dynamic knee-extension strength (1-RM), quadriceps cross-sectional area (CSA), MSTN, follistatin-like related genes (FLST, FLST-3), activin IIb, growth and differentiation factor- associated serum protein 1 (GASP-1), and MAD-related protein (SMAD-7) mRNA gene expression were assessed pre- and post-training. RESULTS:: Knee extension 1-RM significantly increased in all groups (LI: 20.7%, LIR: 40.1%, and HI: 36.2%). CSA increased in both LIR and HI groups (6.3 and 6.1%, respectively). MSTN mRNA expression decreased in the LIR and HI groups (45% and 41%, respectively). There were no significant changes in activin IIb (p>0.05). FLST and FLST-3 mRNA expression increased in all groups from pre- to post-test (p<0.001). FLST-3 expression was significantly greater in the HI when compared to LIR and LI groups at post-test (p=0.024 and p=0.018, respectively). GASP-1 and SMAD-7 gene expression significantly increased in both LIR and HI groups. CONCLUSION:: We concluded that LIR was able to induce similar gains in 1-RM and quadriceps CSA than those observed after traditional HI. These responses may be related to the concomitant decrease in MSTN and increase in FLST-isoforms, GASP-1 and SMAD-7 mRNA gene expression.

Bioenergetics and Neuromuscular Determinants of the Time to Exhaustion at Velocity Corresponding to &OV0312;O2max in Recreational Long-distance Runners

Journal of Strength and Conditioning Research / National Strength & Conditioning Association. Oct, 2011  |  Pubmed ID: 22027852

The purpose of the present study was to investigate the main bioenergetics and neuromuscular determinants of the time to exhaustion (Tlim) at the velocity corresponding to maximal oxygen uptake in recreational long-distance runners. Twenty runners performed the following tests on five different days: 1) maximal incremental treadmill test, 2) two sub-maximal tests to determine running economy (RE) and vertical stiffness (VS), 3) exhaustive test to measured the Tlim, 4) maximum dynamic strength test, and 5) muscle power production test. Aerobic and anaerobic energy contributions during the Tlim test were also estimated. The stepwise multiple regression method selected three independent variables to explain Tlim variance. Total energy production explained 84.1% of the shared variance (p=0.001), while peak oxygen uptake (VO2peak) measured during Tlim and lower limb muscle power ability accounted for additional 10% of the shared variance (p=0.014). These data suggest Powered by Editorial Manager® and Preprint Manager® from Aries Systems Corporationthat the total energy production, VO2peak, and lower limb muscle power ability are the main physiological and neuromuscular determinants of Tlim in recreational long-distance runners.

Effects of Strength and Power Training on Neuromuscular Adaptations and Jumping Movement Pattern and Performance

Journal of Strength and Conditioning Research / National Strength & Conditioning Association. Jan, 2012  |  Pubmed ID: 22222321

This study aimed at comparing the effects of strength and power training regimens on neuromuscular adaptations and changes on vertical jump performance, kinetics and kinematics parameters. Forty physically active males (178.2±7.0 cm; 75.1±8.6 kg; 23.6±3.5 years) with at least two years of strength training experience were assigned to a strength training (ST; n=14), a power training (PT; n=14), or a control group (C; n=12). The training programs were performed during eight weeks, three times per week. Dynamic and isometric maximum strength, cross-sectional area and muscle activation were assessed before and after the experimental period. Squat jump (SJ) and counter movement jump (CMJ) performance, kinetics and kinematics parameters were also assessed. Dynamic maximum strength increased similarly (p<0.05) for the ST (22.8%) and PT (16.6%) groups. MVIC increased for ST and PT groups (p<0.05) in the post-training assessments. There was a main time effect for muscle fiber crosssectional area (p<0.05) but there were no changes in muscle activation. SJ height increased, after ST and PT, due to a faster concentric phase and higher RFD (p<0.05). CMJ height increased only after PT (p<0.05) but there were no significant changes in its kinetics and kinematics parameters. In conclusion, neuromuscular adaptations were similar between the training groups. PT seemed more effective than ST in increasing jumping performance, but neither the ST nor the PT was able to affect the SJ and the CMJ movement pattern (e.g., timing and sequencing of joint extension initiation).

Waiting
simple hit counter