In JoVE (2)

Other Publications (27)

Articles by Hamilton Roschel in JoVE

 JoVE Biology

Determining the Contribution of the Energy Systems During Exercise

1Laboratory of Applied Nutrition, School of Physical Education and Sport, University of Sao Paulo, 2Aerobic Performance Research Group, School of Physical Education and Sport, University of Sao Paulo, 3Laboratory of Neuromuscular Adaptations to Strength Training, School of Physical Education and Sport, University of Sao Paulo, 4Martial Arts and Combat Sports Research Group, School of Physical Education and Sport, University of Sao Paulo

Other articles by Hamilton Roschel on PubMed

Effect of Aspartate and Asparagine Supplementation on Fatigue Determinants in Intense Exercise

International Journal of Sport Nutrition and Exercise Metabolism. Mar, 2003  |  Pubmed ID: 12660406

This study evaluated the effect of aspartate (ASP) and asparagine (ASG) supplementation on fatigue determinants in Wistar rats exercised to exhaustion by swimming.

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.

Responsiveness to Exercise Training in Juvenile Dermatomyositis: a Twin Case Study

BMC Musculoskeletal Disorders. 2010  |  Pubmed ID: 21106107

Patients with juvenile dermatomyositis (JDM) often present strong exercise intolerance and muscle weakness. However, the role of exercise training in this disease has not been investigated.

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.

Creatine Supplementation Spares Muscle Glycogen During High Intensity Intermittent Exercise in Rats

Journal of the International Society of Sports Nutrition. 2010  |  Pubmed ID: 20205834

The effects of creatine (CR) supplementation on glycogen content are still debatable. Thus, due to the current lack of clarity, we investigated the effects of CR supplementation on muscle glycogen content after high intensity intermittent exercise in rats.

Beta-alanine (Carnosyn™) Supplementation in Elderly Subjects (60-80 years): Effects on Muscle Carnosine Content and Physical Capacity

Amino Acids. Dec, 2011  |  Pubmed ID: 22143432

The aim of this study was to investigate the effects of beta-alanine supplementation on exercise capacity and the muscle carnosine content in elderly subjects. Eighteen healthy elderly subjects (60-80 years, 10 female and 4 male) were randomly assigned to receive either beta-alanine (BA, n = 12) or placebo (PL, n = 6) for 12 weeks. The BA group received 3.2 g of beta-alanine per day (2 × 800 mg sustained-release Carnosyn™ tablets, given 2 times per day). The PL group received 2 × (2 × 800 mg) of a matched placebo. At baseline (PRE) and after 12 weeks (POST-12) of supplementation, assessments were made of the muscle carnosine content, anaerobic exercise capacity, muscle function, quality of life, physical activity and food intake. A significant increase in the muscle carnosine content of the gastrocnemius muscle was shown in the BA group (+85.4%) when compared with the PL group (+7.2%) (p = 0.004; ES: 1.21). The time-to-exhaustion in the constant-load submaximal test (i.e., TLIM) was significantly improved (p = 0.05; ES: 1.71) in the BA group (+36.5%) versus the PL group (+8.6%). Similarly, time-to-exhaustion in the incremental test was also significantly increased (p = 0.04; ES 1.03) following beta-alanine supplementation (+12.2%) when compared with placebo (+0.1%). Significant positive correlations were also shown between the relative change in the muscle carnosine content and the relative change in the time-to-exhaustion in the TLIM test (r = 0.62; p = 0.01) and in the incremental test (r = 0.48; p = 0.02). In summary, the current data indicate for the first time, that beta-alanine supplementation is effective in increasing the muscle carnosine content in healthy elderly subjects, with subsequent improvement in their exercise capacity.

Reduced Muscle Carnosine Content in Type 2, but Not in Type 1 Diabetic Patients

Amino Acids. Nov, 2011  |  Pubmed ID: 22120670

Carnosine is present in high concentrations in skeletal muscle where it contributes to acid buffering and functions also as a natural protector against oxidative and carbonyl stress. Animal studies have shown an anti-diabetic effect of carnosine supplementation. High carnosinase activity, the carnosine degrading enzyme in serum, is a risk factor for diabetic complications in humans. The aim of the present study was to compare the muscle carnosine concentration in diabetic subjects to the level in non-diabetics. Type 1 and 2 diabetic patients and matched healthy controls (total n = 58) were included in the study. Muscle carnosine content was evaluated by proton magnetic resonance spectroscopy (3 Tesla) in soleus and gastrocnemius. Significantly lower carnosine content (-45%) in gastrocnemius muscle, but not in soleus, was shown in type 2 diabetic patients compared with controls. No differences were observed in type 1 diabetic patients. Type II diabetic patients display a reduced muscular carnosine content. A reduction in muscle carnosine concentration may be partially associated with defective mechanisms against oxidative, glycative and carbonyl stress in muscle.

In Sickness and in Health: the Widespread Application of Creatine Supplementation

Amino Acids. Nov, 2011  |  Pubmed ID: 22101980

There is an extensive and still growing body of the literature supporting the efficacy of creatine (Cr) supplementation. In sports, creatine has been recognized as the most effective nutritional supplement in enhancing exercise tolerance, muscle strength and lean body mass. From a clinical perspective, the application of Cr supplementation is indeed exciting. Evidences of benefits from this supplement have been reported in a broad range of diseases, including myopathies, neurodegenerative disorders, cancer, rheumatic diseases, and type 2 diabetes. In addition, after hundreds of published studies and millions of exposures creatine supplementation maintains an excellent safety profile. Thus, we contend that the widespread application of this supplement may benefit athletes, elderly people and various patient populations. In this narrative review, we aimed to summarize both the ergogenic and therapeutic effects of Cr supplementation. Furthermore, we reviewed the impact of Cr supplementation on kidney function.

Cardiac Autonomic Impairment and Chronotropic Incompetence in Fibromyalgia

Arthritis Research & Therapy. Nov, 2011  |  Pubmed ID: 22098761

ABSTRACT: INTRODUCTION: We aimed to gather knowledge on the cardiac autonomic modulation in patients with fibromyalgia (FM) in response to exercise and to investigate whether this population suffers from chronotropic incompetence (CI). METHODS: Fourteen women with FM (age: 46 ± 3 years; body mass index (BMI): 26.6 ± 1.4 kg/m2) and 14 gender-, BMI- (25.4 ± 1.3 kg/m2), and age-matched (age: 41 ± 4 years) healthy individuals (CTRL) took part in this cross-sectional study. A treadmill cardiorespiratory test was performed and heart-rate (HR) response during exercise was evaluated by the chronotropic reserve. HR recovery (deltaHRR) was defined as the difference between HR at peak exercise and at both first (deltaHRR1) and second (deltaHRR2) minutes after the exercise test. RESULTS: FM patients presented lower maximal oxygen consumption (VO2 max) when compared with healthy subjects (22 ± 1 versus CTRL: 32 ± 2 mL/kg/minute, respectively; P < 0.001). Additionally, FM patients presented lower chronotropic reserve (72.5 ± 5 versus CTRL: 106.1 ± 6, P < 0.001), deltaHRR1 (24.5 ± 3 versus CTRL: 32.6 ± 2, P = 0.059) and deltaHRR2 (34.3 ± 4 versus CTRL: 50.8 ± 3, P = 0.002) than their healthy peers. The prevalence of CI was 57.1% among patients with FM. CONCLUSIONS: Patients with FM who undertook a graded exercise test may present CI and delayed HR recovery, both being indicative of cardiac autonomic impairment and higher risk of cardiovascular events and mortality.

Familiarisation with Lower Limb Strength Testing in Middle-aged Women with Osteoarthritis of the Knee

Physiotherapy. Dec, 2011  |  Pubmed ID: 22051593

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.

Creatine Supplementation Does Not Augment Muscle Carnosine Content in Type 2 Diabetic Patients

Applied Physiology, Nutrition, and Metabolism = Physiologie Appliquée, Nutrition Et Métabolisme. Oct, 2011  |  Pubmed ID: 21999299

We examined whether creatine supplementation affects muscle carnosine content in type 2 diabetic patients. Subjects were randomly assigned to receive either creatine (5 g·day(-1)) or placebo in a double-blind fashion. At baseline and after 12 weeks, carnosine content was evaluated in gastrocnemius and soleus muscles by using a 1H-MRS technique. No changes were found in gastrocnemius (p = 0.81) and soleus (p = 0.85). We concluded that creatine supplementation does not augment muscle carnosine content in type 2 diabetic patients.

Therapeutic Effects of Exercise Training in Patients with Pediatric Rheumatic Diseases

Revista Brasileira De Reumatologia. Nov, 2011  |  Pubmed ID: 21953000

Over the past decades, the role of exercise training in rheumatic diseases has been largely explored. Currently, physical activity is well known to benefit patients with osteoporosis, osteoarthritis, systemic lupus erythematosus, systemic sclerosis, idiopathic inflammatory myopathy, fibromyalgia and rheumatoid arthritis. Therefore, exercise training has been considered a valuable tool for treating rheumatic patients. The therapeutic effects of exercise training have also been investigated in pediatric rheumatic diseases. Collectively, studies have revealed the therapeutic potential of exercise in juvenile idiopathic arthritis, juvenile systemic lupus erythematosus, juvenile dermatomyositis, juvenile fibromyalgia and other causes of chronic pain. The aim of this review is to familiarize the pediatric rheumatologist with the exercise science field; discuss the potential benefits of exercise training in pediatric rheumatic diseases, emphasize both research and clinical perspectives of this promising field; and propose practical models of pre-participation examinations and contraindications to exercise.

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.

Strength Capacity in Young Patients Who Are Receiving Maintenance Therapy for Acute Lymphoblastic Leukemia: a Case-control Study

Clinics (São Paulo, Brazil). 2011  |  Pubmed ID: 21876987

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.

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.

Effect of Eccentric Exercise Velocity on Akt/mtor/p70(s6k) Signaling in Human Skeletal Muscle

Applied Physiology, Nutrition, and Metabolism = Physiologie Appliquée, Nutrition Et Métabolisme. Apr, 2011  |  Pubmed ID: 21609291

It has been suggested that muscle tension plays a major role in the activation of intracellular pathways for skeletal muscle hypertrophy via an increase in mechano growth factor (MGF) and other downstream targets. Eccentric exercise (EE) imposes a greater amount of tension on the active muscle. In particular, high-speed EE seems to exert an additional effect on muscle tension and, thus, on muscle hypertrophy. However, little is known about the effect of EE velocity on hypertrophy signaling. This study investigated the effect of acute EE-velocity manipulation on the Akt/mTORCI/p70(S6K) hypertrophy pathway. Twenty subjects were assigned to either a slow (20°·s(-1); ES) or fast EE (210°·s(-1); EF) group. Biopsies were taken from vastus lateralis at baseline (B), immediately after (T1), and 2 h after (T2) the completion of 5 sets of 8 repetitions of eccentric knee extensions. Akt, mTOR, and p70(S6K) total protein were similar between groups, and did not change postintervention. Further, Akt and p70(S6K) protein phosphorylation were higher at T2 than at B for ES and EF. MGF messenger RNA was similar between groups, and only significantly higher at T2 than at B in ES. The acute manipulation of EE velocity does not seem to differently influence intracellular hypertrophy signaling through the Akt/mTORCI/p70S6K pathway.

Exercise in a Child with Systemic Lupus Erythematosus and Antiphospholipid Syndrome

Medicine and Science in Sports and Exercise. Dec, 2011  |  Pubmed ID: 21606873

Exercise training has emerged as a potential therapeutic strategy to counteract the decline in physical function and aerobic capacity in pediatric rheumatic disease.

Effect of Creatine Supplementation on Measured Glomerular Filtration Rate in Postmenopausal Women

Applied Physiology, Nutrition, and Metabolism = Physiologie Appliquée, Nutrition Et Métabolisme. Jun, 2011  |  Pubmed ID: 21574777

We aimed to investigate whether creatine supplementation affects the measured glomerular filtration rate in postmenopausal women (age, 58 ± 3 years). Subjects were randomly assigned to receive either creatine (20 g·day(-1) for 1 week and 5 g·day(-1) thereafter) or a placebo. Kidney function was assessed at baseline and after 12 weeks. [(51)Cr]EDTA clearance remained unchanged (CR-PRE: 86.16 ± 14.36 mL·min(-1) per 1.73 m(2), POST: 87.25 ± 17.60 mL·min(-1) per 1.73 m(2); PL-PRE: 85.15 ± 8.54 mL·min(-1) per 1.73 m(2), POST: 87.18 ± 9.64 mL·min(-1) per 1.73 m(2); p = 0.81). Thus, we concluded that creatine supplementation does not affect glomerular filtration rate in postmenopausal women.

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.

Beneficial Effect of Creatine Supplementation in Knee Osteoarthritis

Medicine and Science in Sports and Exercise. Aug, 2011  |  Pubmed ID: 21311365

The aim of this study was to investigate the efficacy of creatine (CR) supplementation combined with strengthening exercises in knee osteoarthritis (OA).

Creatine Supplementation Does Not Impair Kidney Function in Type 2 Diabetic Patients: a Randomized, Double-blind, Placebo-controlled, Clinical Trial

European Journal of Applied Physiology. May, 2011  |  Pubmed ID: 20976468

Creatine supplementation may have a therapeutic role in diabetes, but it is uncertain whether this supplement is safe for kidney function. The aim of this study was to investigate the effects of creatine supplementation on kidney function in type 2 diabetic patients. A randomized, double-blind, placebo-controlled trial was performed. The patients were randomly allocated to receive either creatine or placebo for 12 weeks. All the patients underwent exercise training throughout the trial. Subjects were assessed at baseline and after the intervention. Blood samples and 24-h urine samples were obtained for kidney function assessments. Additionally, (51)Cr-EDTA clearance was performed. To ensure the compliance with creatine intake, we also assessed muscle phosphorylcreatine content. The creatine group presented higher muscle phosphorylcreatine content when compared to placebo group (CR Pre 44 ± 10, Post 70 ± 18 mmol/kg/wt; PL Pre 52 ± 13, Post 46 ± 13 mmol/kg/wt; p = 0.03; estimated difference between means 23.6; 95% confidence interval 1.42-45.8). No significant differences were observed for (51)Cr-EDTA clearance (CR Pre 90.4 ± 16.9, Post 96.1 ± 15.0 mL/min/1.73 m(2); PL Pre 97.9 ± 21.6, Post 96.4 ± 26.8 mL/min/1.73 m(2); p = 0.58; estimated difference between means -0.3; 95% confidence interval -24.9 to 24.2). Creatinine clearance, serum and urinary urea, electrolytes, proteinuria, and albuminuria were unchanged. CR supplementation does not affect kidney function in type 2 diabetic patients, opening a window of opportunities to explore its promising therapeutic role in this population. registration number: NCT00992043.

Creatine in Type 2 Diabetes: a Randomized, Double-blind, Placebo-controlled Trial

Medicine and Science in Sports and Exercise. May, 2011  |  Pubmed ID: 20881878

Creatine supplementation improves glucose tolerance in healthy subjects.

Anthropometric, Physiological, Performance, and Nutritional Profile of the Brazil National Canoe Polo Team

Journal of Sports Sciences. 2012  |  Pubmed ID: 22168392

Abstract The purpose of this study was to determine the physiological, anthropometric, performance, and nutritional characteristics of the Brazil Canoe Polo National Team. Ten male canoe polo athletes (age 26.7 ± 4.1 years) performed a battery of tests including assessments of anthropometric parameters, upper-body anaerobic power (Wingate), muscular strength, aerobic power, and nutritional profile. In addition, we characterized heart rate and plasma lactate responses and the temporal pattern of the effort/recovery during a simulated canoe polo match. The main results are as follows: body fat, 12.3 ± 4.0%; upper-body peak and mean power, 6.8 ± 0.5 and 4.7 ± 0.4 W · kg(-1), respectively; 1-RM bench press, 99.1 ± 11.7 kg; peak oxygen uptake, 44.3 ± 5.8 mL · kg(-1) · min(-1); total energy intake, 42.8 ± 8.6 kcal · kg(-1); protein, carbohydrate, and fat intakes, 1.9 ± 0.1, 5.0 ± 1.5, and 1.7 ± 0.4 g · kg(-1), respectively; mean heart rate, 146 ± 11 beats · min(-1); plasma lactate, 5.7 ± 3.8 mmol · L(-1) at half-time and 4.6 ± 2.2 mmol · L(-1) at the end of the match; effort time (relative to total match time), 93.1 ± 3.0%; number of sprints, 9.6 ± 4.4. The results of this study will assist coaches, trainers, and nutritionists in developing more adequate training programmes and dietary interventions for canoe polo athletes.

Distinct Temporal Organizations of the Strength- and Power-training Loads Produce Similar Performance Improvements

Journal of Strength and Conditioning Research / National Strength & Conditioning Association. Feb, 2012  |  Pubmed ID: 22362090

This study aimed to compare the effects of distinct temporal organizations of strength and power training loads on strength, power, and speed improvements. Sixty soldiers with at least one year in the army volunteered for this study. The subjects were divided into four groups: control group (CG: n = 15; 20.18 ± 0.72 yrs; 1.74 ± 0.06 m; and 66.7 ± 9.8 kg); successive-mesocycle group (SMG: n = 15; 20.11 ± 0.7 yrs; 1.72 ± 0.045 m; and 63.1 ± 3.6 kg); successive-week group (SWG: n = 15; 20.36 ± 0.64 yrs; 1.71 ± 0.05 m; and 66.1 ± 8.0 kg); and simultaneous daily group (SDG: n = 15; 20.27 ± 0.75 yrs; 1.71 ± 0.068 m; and 64.0 ± 8.8 kg). In the SMG, heavy resistance training (HRT), jump squat exercise (JS), and counter movement jumps (CMJ) were performed in successive mesocycles of three weeks each. In the SWG, HRT, JS, and CMJ were trained in one-week blocks into three mesocycles of three weeks each. In the SDG, HRT, JS, and CMJ were trained daily in all of the three mesocycles of three weeks each. Total volume was equalized between groups. The following dependent variables were analyzed: squat 1 RM, CMJ height, 20-m sprint speed, mean power (MP) and mean propulsive power (MPP) in the squat exercise (60% of the squat 1 R M) and in the JS (45% of the squat 1 RM). Significant improvements for all of the dependent variables were detected from pre- to post-training in all of the training groups (p≤0.05), without any between-group differences. Our data suggest that the temporal organization of the training load is not critical for performance improvements in this population.

Exercise Training Counterbalances Chronotropic Incompetence and Delayed Heart Rate Recovery in Systemic Lupus Erythematosus: A Randomized Trial

Arthritis Care & Research. Mar, 2012  |  Pubmed ID: 22438298

OBJECTIVE: To evaluate the efficacy of a three-month exercise training program in counteracting the chronotropic incompetence and delayed heart rate recovery in patients with systemic lupus erythemathosus. METHODS: A 12-wk, randomized trial was conducted. Twenty four inactive SLE patients were randomly assigned into two groups: trained (T, n=15, three-month exercise program) and non-trained (NT, n=13). Agender-, BMI-, and age-matched healthy control group (C, n=8) also underwent the exercise program. Subjects were assessed at baseline (PRE) and 12 weeks after training (POST). Main measurements included the chronotropic reserve (CR) and the heart rate recovery (ΔHRR) as defined by the difference between HR at peak exercise and at both first (ΔHRR1) and second (ΔHRR2) minutes after the exercise test. RESULTS: Neither the non-trained SLE (NT) patients nor the healthy control group (C) presented any change in the chronotropic reserve or in ΔHRR1 and ΔHRR2 (p>0.05). The exercise training program was effective in promoting significant increases in chronotropic reserve (p=0.007; ES=1.15), and in ΔHRR1 and ΔHRR2 (p=0.009; ES=1.12 and p=0.002; ES=1.11, respectively) in the SLE trained group (T) when compared with the NT group. Moreover, the heart rate response in SLE patients after training achieved parameters comparable to the healthy control subjects, as evidenced by the ANOVA and by the Z-score analysis (p>0.05, T vs. C). SLEDAI scoresremained stable throughout the study. CONCLUSION: A 3-month exercise training program was safe and capable of reducing the chronotropic incompetence and the delayed heart rate recovery observed in physically inactive SLE patients. © 2012 by the American College of Rheumatology.

simple hit counter