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1.
Does extensive on-water rowing increase muscular strength and endurance?
Lawton, TW, Cronin, JB, McGuigan, MR
Journal of sports sciences. 2012;(6):533-40
Abstract
The purpose of this study was to compare changes in aerobic condition, strength, and muscular endurance following 8 weeks of endurance rowing alone or in combination with weight-training. Twenty-two elite rowers were assigned to (1) rowing (n = 10, 250-270 km · week⁻¹) or (2) rowing (n = 12, 190-210 km · week⁻¹) plus four weight-training sessions each week. Pre and post mean and standardized effect-size (ES) differences in aerobic condition (watts at 4 mmol · L⁻¹) and strength (isometric pull, N), prone bench-pull (6-repetition maximum, 6-RM), 5- and 30-repetition leg-press and 60-repetition seated-arm-pull (J, performed on a dynamometer) normalized by body mass and log-transformed were analysed, after adjusting for gender. The standardized differences between groups were trivial for aerobic condition (ES [±90% CI] = 0.15; ±0.28, P = 0.37) and prone bench-pull (ES = 0.27; ±0.33, P = 0.18), although a moderate positive benefit in favour of rowing only was observed for the seated-arm-pull (ES = 0.42; ±0.4, P = 0.08). Only the weight-training group improved isometric pull (12.4 ± 8.9%, P < 0.01), 5-repetition (4.0 ± 5.7%, P < 0.01) and 30-repetition (2.4 ± 5.4%, P < 0.01) leg-press. In conclusion, while gains in aerobic condition and upper-body strength were comparable to extensive endurance rowing, weight-training led to moderately greater lower-body muscular-endurance and strength gains.
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2.
Responses of elbow flexors to two strenuous eccentric exercise bouts separated by three days.
Chen, TC, Nosaka, K
Journal of strength and conditioning research. 2006;(1):108-16
Abstract
This study investigated whether the second eccentric exercise performed 3 days after the initial bout would exacerbate muscle damage and retard the recovery. Fifty-one athletes performed 30 eccentric actions of the elbow flexors using a dumbbell weighted 100% of the maximal isometric force (MIF) at the elbow joint angle of 90 degrees (ECC1). Three days after ECC1, all subjects except those in the control group (n = 12) performed the second bout (ECC2) with the same (100%) intensity (n = 12), 90% (n = 13), or 80% (n = 14) of the ECC1. Some subjects, especially in the 100% group, required spotting for ECC2 but made maximal effort to complete the exercise. MIF, range of motion, upper-arm circumference, muscle soreness, muscle proteins in the blood, and ultrasound images were used to assess muscle damage. Changes in these measures for 9 days following ECC1 were compared among groups by 2-way analysis of variance (ANOVA) with repeated measures. All criterion measures changed significantly after ECC1; however, no significant differences between the groups were evident for any of the changes in the measures. These results suggest that it is possible for athletes to complete the second bout if the intensity is reduced 10-20% from the initial bout. No significant differences between the control group and other groups indicate that the second eccentric exercise performed 3 days after the initial bout does not exacerbate muscle damage and retard the recovery regardless of the intensity of the second bout. It is concluded that the elbow flexors can perform high-intensity eccentric exercise in the early stage of recovery from the initial bout and are not damaged further by performing a subsequent bout 3 days after the first.
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3.
A single session of resistance exercise does not reduce postprandial lipaemia.
Burns, SF, Corrie, H, Holder, E, Nightingale, T, Stensel, DJ
Journal of sports sciences. 2005;(3):251-60
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Abstract
This study investigated the effect of a single session of resistance exercise on postprandial lipaemia. Eleven healthy normolipidaemic men with a mean age of 23 (standard error = 1.4) years performed two trials at least 1 week apart in a counterbalanced randomized design. In each trial, participants consumed a test meal (1.2 g fat, 1.1 g carbohydrate, 0.2 g protein and 68 kJ x kg(-1) body mass) between 08.00 and 09.00 h following a 12 h fast. The afternoon before one trial, the participants performed an 88 min bout of resistance exercise. Before the other trial, the participants were inactive (control trial). Resistance exercise was performed using free weights and included four sets of 10 repetitions of each of 11 exercises. Sets were performed at 80% of 10-repetition maximum with a 2 min work and rest interval. Venous blood samples were obtained in the fasted state and at intervals for 6 h postprandially. Fasting plasma triacylglycerol (TAG) concentration did not differ significantly between control (1.03 +/- 0.13 mmol x l(-1)) and exercise (0.94 +/- 0.09 mmol x l(-1)) trials (mean +/- standard error). Similarly, the 6 h total area under the plasma TAG concentration versus time curve did not differ significantly between the control (9.84 +/- 1.40 mmol l(-1) x 6 h(-1)) and exercise (9.38 +/- 1.12 mmol x l(-1) x 6 h(-1)) trials. These findings suggest that a single session of resistance exercise does not reduce postprandial lipaemia.
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High-affinity growth hormone binding protein and acute heavy resistance exercise.
Rubin, MR, Kraemer, WJ, Maresh, CM, Volek, JS, Ratamess, NA, Vanheest, JL, Silvestre, R, French, DN, Sharman, MJ, Judelson, DA, et al
Medicine and science in sports and exercise. 2005;(3):395-403
Abstract
PURPOSE The purpose of this investigation was to examine the influence of resistance training on circulating concentrations of growth hormone binding protein (GHBP) in response to acute heavy resistance exercise. METHODS Using a cross-sectional experimental design, a group of resistance-trained men (RT, N=9, 7.9+/-1.3 yr resistance training experience) and a group of untrained men (UT, N=10) performed an acute heavy resistance exercise protocol (AHREP) consisting of 6 sets of 10 repetition maximum parallel squats. Blood samples were obtained 72 h before exercise, immediately before exercise, and 0, 15, 30, 45, and 60 min after exercise. RESULTS Significant increases (P<0.05) in GHBP, immunoreactive growth hormone (iGH), and IGF-1 were observed in both subject groups after AHREP. There were no differences (P>0.05) between groups in GHBP at rest or after AHREP. However, RT exhibited a significantly greater iGH response to AHREP than UT subjects, and significantly higher IGF-1 values at rest and after exercise. Significant positive correlations were found between GHBP and BMI, body fat, and leptin in both groups. A significant positive correlation also was observed between resting leptin and GHBP values in UT but not RT subjects. CONCLUSIONS In summary, these data indicate that resistance training does not increase blood GHBP. Nevertheless, the increases observed with IGF-1 concentrations in the resistance-trained subjects do suggest an apparent adaptation with the regulation of this hormone. If there was in fact an increase in GH sensitivity and GH receptor expression at the liver that was not detected by blood GHBP in this study, it may be possible that factors contributing to the circulating concentration of GHBP other than hepatocytes (e.g., leptin and adipocytes) may serve to mask training-induced increases in circulating GHBP of a hepatic origin, thus masking any detectable increase in GH receptor expression.
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Blood lipid peroxides and muscle damage increased following intensive resistance training of female weightlifters.
Liu, JF, Chang, WY, Chan, KH, Tsai, WY, Lin, CL, Hsu, MC
Annals of the New York Academy of Sciences. 2005;:255-61
Abstract
The aim of this study was to examine changes in muscle cell injury and antioxidant capacity of weightlifters following a 1-week intensive resistance-training regimen. Thirty-six female subjects participated in this study, and their ages ranged from 18 to 25 years. The sample group included 19 elite weightlifters with more than 3 years of weightlifting training experience, while the control group comprised 17 non-athletic individuals. Compared with non-athletes, weightlifters had significantly lower glutathione peroxidase activity and plasma vitamin C concentrations. Weightlifters also had significantly higher malondialdehyde + 4-hydroxy 2-(E)-nonenal (MDA+4-HNE) and thiobarbituric acid-reactive substance (TBARS) levels and creatine kinase (CK) activity. For weightlifters, the plasma vitamin E level and the activity of superoxide dismutase (SOD) decreased, and CK activity increased significantly (P < 0.05) after a 1-week intensive resistance-training regimen. Both the TBARS levels and CK activity returned to values of pre-intensive training after a 2-day rest. The MDA+4-HNE level strongly correlated with CK activity in weightlifters (P < 0.05). In conclusion, both long-term exercise training and 1 week of intensive resistance training resulted in increased oxidative stress and cell injury in female weightlifters. Furthermore, proper rest after intensive training was found to be important for recovery.
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TLR4 is lower in resistance-trained older women and related to inflammatory cytokines.
McFarlin, BK, Flynn, MG, Campbell, WW, Stewart, LK, Timmerman, KL
Medicine and science in sports and exercise. 2004;(11):1876-83
Abstract
INTRODUCTION/PURPOSE Regular exercise may offset age-associated increases in inflammatory cytokines and reduce the risk of developing diseases with an inflammatory etiology by exerting "anti-inflammatory" effects. Toll-like receptor 4 (TLR4) signaling stimulates inflammatory cytokine production, and may explain the "anti-inflammatory" effect attributed to regular exercise. Therefore, the purpose of the present study was to compare the effect of acute (3 sets, 9 exercises, 10 repetitions at 80% of the 1-repetition maximum) and chronic resistance exercise on TLR4 and inflammatory cytokines. METHODS Venous blood samples were collected from trained (TR, N = 10) and untrained (UT, N = 10) older (65-80 yr) postmenopausal women: before (PRE), immediately post (POST), and 2 h (2H), 6 h (6H), and 24 h (24H) after completion of exercise. Cell-surface expression of TLR4 (two-color immunofluorescent cytometry), LPS (25 microg x mL(-1))-stimulated cytokine production (ELISA), plasma cytokines (ELISA), and mRNA expression of TLR4 and cytokines (RT-PCR) were determined for each sample. RESULTS TR had 124% less cell-surface TLR4 expression than UT (P < 0.05). A significant time effect was found for LPS-stimulated IL-6, IL-1beta, and TNF-alpha, where 6H was significantly greater than all other samples. No significant effects were found for plasma (IL-6 and TNF-alpha) or mRNA expression (IL-6, TNF-alpha, and IL-1beta) of inflammatory cytokines. When subjects were grouped according to cell-surface TLR4 expression (HI and LO), LPS-stimulated TNF-alpha (302%), IL-1beta (209%), and IL-6 (167%) production was greater for HI than LO (P < 0.05). CONCLUSION Regularly exercising older women expressed less cell-surface TLR4 but did not have lower plasma levels or produce less LPS-stimulated inflammatory cytokines at rest or in response to a single bout of resistance exercise. TLR4 changes may explain the "anti-inflammatory" effect that has recently been attributed to chronic (2x wk for previous 24 months) resistance exercise training.
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Difference in the magnitude of muscle damage between maximal and submaximal eccentric loading.
Nosaka, K, Newton, M
Journal of strength and conditioning research. 2002;(2):202-8
Abstract
This study compared maximal (MAX-ECC) and submaximal (50%-ECC) eccentric exercise of the elbow flexors. Untrained male students (n = 8) performed 3 sets of 10 repetitions of MAX-ECC with one arm and 50%-ECC with the other arm, separated by 4 weeks. In MAX-ECC, the elbow joint was forcibly extended from a flexed (90 degrees ) to a full-extended position (180 degrees ) in 3 seconds while producing maximal force. For 50%-ECC, a dumbbell set at 50% of the maximal isometric strength at 90 degrees of the elbow joint was lowered from the flexed to the extended position in 3 seconds. Changes in indicators of muscle damage were compared between the bouts by a 2-way repeated-measures analysis of variance. Changes in isometric strength, range of motion, upper arm circumference, and plasma creatine kinase activity were significantly smaller and the recovery was significantly faster for 50%-ECC compared with MAX-ECC, although the differences in the changes immediately after exercise were small. It appeared that the magnitude of initial muscle damage was similar between the bouts; however, secondary damage was less after 50%-ECC.
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8.
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.
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Creatine supplementation results in elevated phosphocreatine/adenosine triphosphate (ATP) ratios in the calf muscle of athletes but not in patients with myopathies.
Zange, J, Kornblum, C, Müller, K, Kurtscheid, S, Heck, H, Schröder, R, Grehl, T, Vorgerd, M
Annals of neurology. 2002;(1):126; author reply 126-7
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10.
The effects of high-dose glutamine ingestion on weightlifting performance.
Antonio, J, Sanders, MS, Kalman, D, Woodgate, D, Street, C
Journal of strength and conditioning research. 2002;(1):157-60
Abstract
The purpose of this study was to determine if high-dose glutamine ingestion affected weightlifting performance. In a double-blind, placebo-controlled, crossover study, 6 resistance-trained men (mean +/- SE: age, 21.5 +/- 0.3 years; weight, 76.5 +/- 2.8 kg(-1)) performed weightlifting exercises after the ingestion of glutamine or glycine (0.3 g x kg(-1)) mixed with calorie-free fruit juice or placebo (calorie-free fruit juice only). Each subject underwent each of the 3 treatments in a randomized order. One hour after ingestion, subjects performed 4 total sets of exercise to momentary muscular failure (2 sets of leg presses at 200% of body weight, 2 sets of bench presses at 100% of body weight). There were no differences in the average number of maximal repetitions performed in the leg press or bench press exercises among the 3 groups. These data indicate that the short-term ingestion of glutamine does not enhance weightlifting performance in resistance-trained men.