Resumos selecionados – 2013/03/12

 

 

 

Crewther BT, Heke TL, Keogh JW. The effects of a resistance-training program on strength, body composition and baseline hormones in male athletes training concurrently for rugby union 7’s. J Sports Med Phys Fitness. 2013 Feb;53(1):34-41.

Aim: To examine the effects of a resistance-training program on strength, body composition and baseline hormones in male athletes training concurrently for rugby union 7’s.

Methods: Participants (N.=12) completed a six-week resistance-training program focusing on general strength development while still performing additional rugby union 7’s training involving agility, speed and cardiovascular fitness. One repetition maximum (1RM) strength was assessed pre and post training across 5 exercises (bench press, back squats, deadlifts, military press and chins), along with body composition and baseline salivary testosterone (T) and cortisol (C) concentrations.

Results: Significant improvements in bench press (11%), back squat (13%), deadlift (13%), military press (10%) and chin-up (6%) 1RM strength were observed after training (P < 0.05). These changes were accompanied by a significant reduction (-1%) in body fat and an increase (1.3%) in fat-free mass. Baseline T and C concentrations and the T/C ratio did not change significantly with training (P>0.05). Correlational analyses indicated that most of the individual changes in strength, body composition and hormones were not significantly related.

Conclusion: The implementation of a resistance-training program in male athletes already training for rugby union 7’s led to all-round improvements in maximal dynamic strength even while they continued to perform other forms of rugby-specific training. These findings support the use of resistance exercise as a supplement to sport-specific training for improving the performance capacity of 7’s rugby players.

 

 

Sparks LM, Johannsen NM, Church TS, Moonen-Kornips E, Moro C, Hesselink MK, Smith SR, Schrauwen P. Nine Months of Combined Training Improves Ex Vivo Skeletal Muscle Metabolism in Individuals With Type 2 Diabetes. J Clin Endocrinol Metab. 2013 Mar 5. [Epub ahead of print]

Context: Type 2 diabetes (T2D) has features of disordered lipid and glucose metabolism, due in part to reduced mitochondrial content.

Objective: Our objective was to investigate effects of different types of exercise on mitochondrial content and substrate oxidation in individuals with T2D (ancillary study of the randomized controlled trial Health Benefits of Aerobic and Resistance Training in Individuals with Type 2 Diabetes, HART-D).

Intervention: T2D individuals were randomized to aerobic training (AT, n = 12), resistance training (RT, n = 18), combination training (ATRT, n = 12), or nonexercise control (n = 10). Blood draws, peak oxygen consumption tests, dual-energy x-ray absorptiometry scans and muscle biopsies of vastus lateralis were performed before and after 9 months. Ex vivo substrate oxidations (14CO2), mitochondrial content, and enzyme activities were measured. Glycated hemoglobin A1c and free fatty acids were also determined.

Results:Mitochondrial content increased after RT and ATRT. Octanoate oxidation increased after AT and ATRT, whereas palmitate, pyruvate, and acetate oxidations increased in all exercise groups. Exercise-induced responses in mitochondrial DNA were associated with improvements in peak oxygen consumption, β-hydroxyacyl-coenzyme A dehydrogenase activity, and palmitate oxidation.

Conclusions:Nine months of AT and RT significantly improved most aspects of skeletal muscle mitochondrial content and substrate oxidation, whereas the combination improved all aspects. These exercise responses were associated with clinical improvements, indicating that long-term training, especially combination, is an effective lifestyle therapy for individuals with T2D by way of improving muscle substrate metabolism.

 

 

Grelier S, Serresse O, Boudreau-Lariviere C, Zory R. Effects of a three-month combined training program on the cardiopulmonary and muscle strength capacities of type 2 diabetic subjects. J Sports Med Phys Fitness. 2013 Feb;53(1):56-64.

Aim: For many years, exercise has been regarded as one of the three primary interventions to treat type 2 diabetes along with diet and medication. Combined exercise programs consisting of both aerobic and resistance training have been demonstrated to have more benefits in a sedentary population than either type of  training alone. This study was designed to evaluate the effects of combined exercise training on physiological parameters (cardiopulmonary, blood, muscle) of a type 2 diabetic population.

Methods: Twelve type 2 diabetic patients (6 males and 6 females) performed a three-month combined exercise program comprised of two sessions of exercise per week. Cardiopulmonary exercise testing, blood sampling, anthropometric measurements and strength tests were carried out on each subject before (PRE) and immediately after (POST) the training program.

Results:The VO2peak and the maximal aerobic power during exercise, the blood profile and the body mass were unchanged after the three-month training program. However, the oxygen uptake and the heart rate at submaximal exercise intensity were significantly lower after the three-month training and muscle strength for many muscle groups was significantly increased. Conclusion: These results highlighted the effectiveness of the combined training to improve submaximal cardiopulmonary efficiency and muscle strength capacity of type 2 diabetic patients.

 

Areta JL, Burke LM, Ross ML, Camera DM, West DW, Broad EM, Jeacocke NA, Moore DR, Stellingwerff T, Phillips SM, Hawley J, Coffey VG. Timing and distribution of protein ingestion during prolonged recovery from resistance exercise alters myofibrillar protein synthesis. J Physiol. 2013 Mar 4. [Epub ahead of print]

 

Quantity and timing of protein ingestion are major factors regulating myofibrillar protein synthesis (MPS). However, the effect of specific ingestion patterns on MPS throughout a 12 h period is unknown. We determined how different distribution of protein feeding during 12 h recovery after resistance exercise affects anabolic responses in skeletal muscle. 24 healthy trained males were assigned to three groups (n=8/group) and undertook a bout of resistance exercise  followed by ingestion of 80 g of whey protein throughout 12 h recovery as either: 8×10 g every 1.5 h (PULSE); 4×20 g every 3 h (intermediate: INT); or 2×40 g every 6 h (BOLUS). Muscle biopsies were obtained at rest and after 1, 4, 6, 7 and 12 h  post-exercise. Resting and post-exercise MPS (L-[ring-13C6] phenylalanine), and muscle mRNA abundance and cell signalling were assessed. All ingestion protocols  increased MPS above rest throughout 1-12 h recovery (88-148%, P<0.02), but INT elicited greater MPS than PULSE and BOLUS (31-48%, P<0.02). In general signalling showed a BOLUS>INT>PULSE hierarchy in magnitude of phosphorylation. MuRF-1 and SLC38A2 mRNA were differentially expressed with BOLUS. In conclusion, 20 g of whey protein consumed every 3 h was superior to either PULSE or BOLUS feeding patterns for stimulating MPS throughout the day. This study provides novel information on the effect of modulating the distribution of protein intake on anabolic responses in skeletal muscle and has potential to maximise outcomes of resistance training for attaining peak muscle mass.

 
Duncan MJ, Smith M, Cook K, James RS. The acute effect of a caffeine-containing energy drink on mood state, readiness to invest effort, and resistance exercise to failure. J Strength Cond Res. 2012 Oct;26(10):2858-65.

The efficacy of caffeine ingestion in enhancing aerobic performance is well established. The evidence for caffeine’s effects on resistance exercise is mixed and has not fully examined the associated psychological and psychophysiological changes. This study examined acute effects of ingesting a caffeine-containing energy drink on repetitions to failure, the rating of perceived exertion (RPE), and the readiness to invest physical effort (RTIPE) and mental effort during resistance exercise to failure. Thirteen resistance-trained men took part in this double-blind, randomized cross-over experimental study whereby they ingested a caffeinated (179 mg) energy drink or placebo solution 60 minutes before completing a bout of resistance exercise comprising bench press, deadlift, prone row, and back squat exercise to failure at an intensity of 60% 1-repetition maximum. Experimental conditions were separated by at least 48 hours. Participants completed significantly greater repetitions to failure, irrespective of exercise, in the energy drink condition (p = 0.015). Rating of perceived exertion was significantly higher in the placebo condition (p = 0.02) and was significantly higher during lower-body exercises compared with upper-body exercises irrespective of the substance ingested (p = 0.0001). Readiness to invest mental effort was greater with the energy drink condition (p = 0.04), irrespective of time. A significant time × substance interaction (p = 0.036) for RTIPE indicated that RTIPE increased for both placebo and energy drink conditions preingestion to pre-exercise, but the magnitude of increase was greater with the energy drink condition compared with placebo. This resulted in higher RTIPE postexercise for the energy drink condition. These results suggest that acute ingestion of a caffeine-containing energy drink can enhance resistance exercise performance to failure and positively enhance psychophysiological factors related to exertion in trained men.

 

 

Tianrun Li, Leiluo Geng, Xin Chen, Miranda MISKOWIEC, Xuan Li, Bing Dong. Branched chain amino acids alleviate non-alcoholic steatohepatitis in rats. Applied Physiology, Nutrition, and Metabolism, 10.1139/apnm-2012-0496

Non-alcoholic steatohepatitis (NASH) is a prevalent disease in worldwide countries. Branched chain amino acids (BCAA), comprised of leucine, isoleucine and valine, cannot be synthesized by the body and have been shown to promote muscle build up, thus it is logical to propose that BCAA can reduce fat deposition in the body. We used gonadectomized rats fed a high fat diet to investigate the effects of BCAA on lipid metabolism over an 8-week experimental period. Body composition, tissue histology, plasma lipid indices and hormone levels were examined. We demonstrated that the body weights of rats were not significantly decreased but the mesenteric fat was significantly decreased (P<0.05) in BCAA treated rats. In addition, BCAA decreased plasma lipids and fat deposition in the liver. At week 4, when the un-treated rats displayed macro-vesicular steatosis, BCAA treated rats had only micro-vescular droplets in their hepatocytes. At week 8, when the un-treated rat livers displayed profound inflammation and cirrhosis, BCAA treated rat livers maintained the macro-vesicular stage of steatosis. BCAA induced higher blood glucose and plasma insulin (P<0.05). BCAA also improved liver blood flow by increasing mean arterial blood pressure and decreasing portal pressure which helped to delay the change of blood flow pattern into that of cirrhosis. BCAA also induced the skeletal muscle to express higher branched chain α-keto acids dehydrogenase E1α which indicated an enhanced metabolic capacity of BCAA in muscle tissues. This study clearly demonstrates the effects of BCAA on amelioration of fat deposition in rats fed high fat diets.

 

 

Litchke LG, Lloyd LK, Schmidt EA, Russian CJ, Reardon RF. Effects of Concurrent Respiratory Resistance Training on Health-Related Quality of Life in Wheelchair Rugby Athletes: A Pilot Study. Top Spinal Cord Inj Rehabil. 2012 Summer;18(3):264-272.

PURPOSE: To compare the effects of 9 weeks of training with a concurrent flow resistance (CFR) device versus a concurrent pressure threshold resistance (CPTR) device on health-related quality of life (HRQoL) in wheelchair rugby (WR) athletes.

METHOD: Twenty-four male WR athletes (22 with tetraplegia, 1 with a spastic cerebral palsy, and 1 with congenital upper and lower limb deformities) were matched by lesion level, completeness of injury, and rugby classification prior to being randomly assigned to 1 of 3 groups: (1) CPTR (n=8), (2) CFR (n=8), or (3) controls (CON, n=8). Pre/post testing included assessment of HRQoL as measured by the Short-Form Health Survey Version 2.0 (SF-36v2). Manufacturer protocol guidelines for the CFR and CPTR groups were followed for breathing exercises.

RESULTS: Sixteen participants completed the study (CPTR=4, CFR=5, CON=7). The Mann-Whitney U rank order revealed significantly greater reductions in bodily pain (P = .038) and improvements in vitality (P = .028) for CFR versus CON. 

CONCLUSION: Results from this study suggest that training with a CFR device improves some aspects of HRQoL (eg, vitality and bodily pain) in WR athletes. Further research with a larger sample size is needed to examine the impact of these devices on improving HRQoL for wheelchair athletes.

 

 

Marques MC, Liberal SM, Costa AM, van den Tillaar R, Sánchez-Medina L, Martins JC, Marinho DA. Effects of two different training programs with same workload on throwing velocity by experienced water polo players. Percept Mot Skills. 2012 Dec;115(3):895-902.

 

To investigate the effects of two different strength-training programs with the same workload (impulse) on throwing velocity in water polo, 30 water polo players (M age = 17.1 yr., SD = 4.9; M mass = 71.2 kg, SD = 14.7; M height = 1.75 m, SD = 0.09 m) were randomly divided in two groups based upon throwing performance with  water polo ball. The medicine-ball training group performed 3 x 6 reps with a 3-kg medicine ball, while the combination training group completed 1 x 9 repetitions with the 3-kg medicine ball, followed by 3 x 14 repetitions with a water polo ball. Both groups trained eight weeks twice per week in addition to their regular water polo training. Throwing velocity was measured with a Doppler  radar gun before and after the training period. Testing included throws with a water polo ball on land and in water, as well as with 1-kg and 3-kg medicine balls on land. Statistically significant increases were found in mean peak throwing velocity with the water polo, 1-kg, and 3-kg medicine balls after training. No differences between the groups were found, except in throwing velocity with water polo on land, with a statistically significantly larger increase for the combination training group (+7.6%) than the medicine-ball training group (+3.4%). These findings indicate that after training with the same workload (impulse), increases in throwing velocity in water polo are similar and suggesting workload may be a critical variable for training results

 

 

 

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