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Changes in metabolic and muscle damage indicators following a single bout of jump training on stair versus at level.
Váczi, M, Tékus, E, Kaj, M, Kőszegi, T, Ambrus, M, Tollár, J, Atlasz, T, Szabadfi, K, Karsai, I
Acta physiologica Hungarica. 2013;(4):445-56
Abstract
UNLABELLED We hypothesized that stair-jump exercise would induce less muscle damage and greater acute metabolic responses than level-jumps. METHODS Trained males executed 100 unilateral jumps on stairs with one leg, and at level with the other leg, with two weeks hiatus. Maximal isometric voluntary torque (MVC) and rate of torque development (RTD)in the quadriceps, and unilateral vertical jump height (VJ) were determined in the trained leg at pre-exercise,immediately at post- (IP), 24 h and 48 h after exercise. Serum creatine kinase (CK) level and delayed onset muscle soreness (DOMS) were evaluated at pre-exercise, 24 h and 48 h. Acute lactate and heart rate responses were also measured. RESULTS Lactate and heart rate at IP increased similarly under the two conditions. CK was elevated and MVC was depressed while RTD and VJ remained unchanged at 24 h in both types of training. MVC recovered at 48 h only after stair-jump exercise. DOMS developed only after level-jumps. Except DOMS, no effects of condition were found in any other variables. CONCLUSIONS We conclude that vigorous stair-jump exercise highly stresses the aerobic and the anaerobic energy system, and it preserves power and rapid torque generating ability 24 h after exercise. Stair-jump could be one alternative exercise to prevent muscle soreness.
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Muscle force and force control after weight loss in obese and morbidly obese men.
Hue, O, Berrigan, F, Simoneau, M, Marcotte, J, Marceau, P, Marceau, S, Tremblay, A, Teasdale, N
Obesity surgery. 2008;(9):1112-8
Abstract
BACKGROUND Decrease in fat mass and fat-free mass have been observed with weight loss induced by a dietary intervention or surgery. There are concerns that fat-free mass decrease could have some negative functional consequences. The aim of this study was to examine how weight loss affects strength and force control in obese and morbidly obese men. METHODS Weight loss was obtained in obese individuals by a hypocaloric diet program until resistance to lose fat and in morbidly obese individuals by bariatric surgery. Maximal force was measured for upper and lower limb and the ability to maintain 15% and 40% of that force. These measures were taken at baseline, in those dieting once resistant to weight loss and 1 year after surgery for those operated on. Normal weight individuals used for control were evaluated twice (6 to 12 months apart). RESULTS At baseline, there was no significant difference between groups for maximal forces and capabilities to maintain force levels. Weight loss averaged 11.1% of the initial body weight after dieting and 46.3% 1 year after surgery. At the same time, there was for the lower limb a loss of 10.1% in maximal force after dieting and 33.5% after surgery. For the upper limb, there was no change in maximal force after dieting whereas a decrease of 14.4% was observed after surgery. When transformed in force related to body weight, there was no change in relative force for the lower limb after dieting whereas an increased relative force after surgery. There was no significant difference for the ability for maintaining force levels. CONCLUSION Despite a large force loss, particularly for the lower limbs in morbidly obese individuals after surgery, this loss is relatively well tolerated because the relation between force and body weight is even improved and the ability to maintain that force is preserved.
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Effects of cold and hot water immersion on the mechanical properties of human muscle and tendon in vivo.
Kubo, K, Kanehisa, H, Fukunaga, T
Clinical biomechanics (Bristol, Avon). 2005;(3):291-300
Abstract
BACKGROUND Cooling and heating have been shown to affect the contractile properties of muscles. However, the reasons for these changes remain unclear. The present study aimed to quantify the mechanical properties of muscle and tendon during passive stretch and active contraction, and to investigate the effects of cooling and heating on the mechanical properties of muscle and tendon. METHODS Before and after these conditions, the elongation of the muscle fascicle, tendon and aponeurosis of the medial gastrocnemius muscle was directly measured by ultrasonography, while the ankle joint was passively moved within the joint range of +15 to -30 deg (0 deg = neutral anatomic position; positive values for plantar flexion) and subjects performed ramp isometric plantar flexion up to the voluntary maximum. FINDINGS While the muscle fascicle, tendon and aponeurosis stretched during passive dorsi-flexion, the elongation of the tendon was significantly greater than that of the aponeurosis. During isometric contraction, the maximal elongation of the tendon was significantly greater than that of the aponeurosis. After cooling and heating, no significant changes in the elongation of muscle fascicle, tendon and aponeurosis were found during passive stretch. Similarly, after both the immersions there were no changes in the relationship between the estimated muscle force and elongation of each structure (tendon-aponeurosis complex, tendon) during isometric contraction. INTERPRETATION These results implied that the general application of icing and hot pack did not change the mechanical properties of muscle and tendon.
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Effects of creatine on isometric bench-press performance in resistance-trained humans.
Kilduff, LP, Vidakovic, P, Cooney, G, Twycross-Lewis, R, Amuna, P, Parker, M, Paul, L, Pitsiladis, YP
Medicine and science in sports and exercise. 2002;(7):1176-83
Abstract
PURPOSE The purpose of this study was to investigate the effects of creatine (Cr) supplementation on force generation during an isometric bench-press in resistance-trained men. METHODS 32 resistance-trained men were matched for peak isometric force and assigned in double-blind fashion to either a Cr or placebo group. Subjects performed an isometric bench-press test involving five maximal isometric contractions before and after 5 d of Cr (20 g.d-1 Cr + 180 g.d-1 dextrose) or placebo (200 g.d-1 dextrose). Body composition was measured before and after supplementation. Subjects completed 24-h urine collections throughout the study period; these were subsequently analyzed to provide total Cr and creatinine excretion. RESULTS The amount of Cr retained over the supplementation period was 45 +/- 18 g (mean +/- SD), with an estimated intramuscular Cr storage of 43 (13-61) mmol x kg(-1) x dry weight muscle (median [range]). Four subjects in the Cr group were classified as "nonresponders" (< or =21 mmol x kg(-1) x dry weight muscle increase following Cr supplementation) and the remaining 17 subjects were classed as "responders" (> or =32 mmol x kg(-1) x dry weight muscle). For the Cr group, peak force and total force pre- or post-supplementation were not different from placebo. However, when the analysis was confined to the responders, both the change in peak force [Repetition 2: 59(81) N vs -26(85) N; Repetition 3: 45(59) N vs -26(64) N) and the change in total force (Repetition 1: 1471(1274) N vs 209(1517) N; Repetition 2: 1575(1254) N vs 196(1413) N; Repetition 3: 1278(1245) N vs -3(1118) N; Repetition 4: 918(935) N vs -83(1095) N] post-supplementation were significantly greater compared with the placebo group (P < 0.01). For the Cr group, estimated Cr uptake was inversely correlated with training status (r = -0.68, N = 21, P = 0.001). Cr significantly increased body weight (84.1 +/- 8.6 kg pre- vs 85.3 +/- 8.3 kg post-supplementation) and fat-free mass (71.8 +/- 6.0 kg pre- vs 72.6 +/- 6.0 kg post-supplementation), with the magnitude of increase being significantly greater in the responder group than in the placebo group. CONCLUSION Five days of Cr supplementation increased body weight and fat-free body mass in resistance-trained men who were classified as responders. Peak force and total force during a repeated maximal isometric bench-press test were also significantly greater in the responders compared to the placebo group.