N D Duncan

University of Melbourne, Melbourne, Victoria, Australia

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Publications (8)19.02 Total impact

  • Article: Influence of compression therapy on symptoms following soft tissue injury from maximal eccentric exercise.
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    ABSTRACT: A between groups design was used to compare recovery following eccentric muscle damage under 2 experimental conditions. To determine if a compression sleeve donned immediately after maximal eccentric exercise would enhance recovery of physical function and decrease symptoms of soreness. Prior investigations using ice, intermittent compression, or exercise have not shown efficacy in relieving symptoms of delayed onset muscle soreness (DOMS). To date, no study has shown the effect of continuous compression on DOMS, yet this would offer a low cost intervention for patients suffering with the symptoms of DOMS. Twenty nonimpaired non-strength-trained women participated in the study. Subjects were matched for age, anthropometric data, and one repetition maximum concentric arm curl strength and then randomly placed into a control group (n = 10) or an experimental compression sleeve group (n = 10). Subjects were instructed to avoid pain-relieving modalities (eg, analgesic medications, ice) throughout the study. The experimental group wore a compressive sleeve garment for 5 days following eccentric exercise. Subjects performed 2 sets of 50 passive arm curls with the dominant arm on an isokinetic dynamometer with a maximal eccentric muscle action superimposed every fourth passive repetition. One repetition maximum elbow flexion, upper arm circumference, relaxed elbow angle, blood serum cortisol, creatine kinase, lactate dehydrogenase, and perception of soreness questionnaires were collected prior to the exercise bout and daily thereafter for 5 days. Creatine kinase was significantly elevated from the baseline value in both groups, although the experimental compression test group showed decreased magnitude of creatine kinase elevation following the eccentric exercise. Compression sleeve use prevented loss of elbow motion, decreased perceived soreness, reduced swelling, and promoted recovery of force production. Results from this study underline the importance of compression in soft tissue injury management.
    Journal of Orthopaedic and Sports Physical Therapy 07/2001; 31(6):282-90. · 3.00 Impact Factor
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    Article: The effect of heavy resistance exercise on the circadian rhythm of salivary testosterone in men.
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    ABSTRACT: Circadian rhythms of serum testosterone concentrations in men have been shown, in general, to be highest in the morning and lowest in the evening. Thus, the purpose of this investigation was to determine the effects of acute resistance exercise upon the waking circadian rhythm of salivary testosterone over 2 days (with or without resistance exercise). The subjects included ten resistance-trained men (with at least 1 year of lifting experience) with the following characteristics [mean (SD)]: age 21.6 (1.1) years; height 177.8 (9.5) cm; body mass 80.5 (11.5) kg; percent body fat 7.9 (1.7)%. A matched, randomized, crossover study design was used such that each subject was tested under both the resistance exercise and control (no exercise) conditions. The resistance exercise protocol consisted of ten exercises performed for three sets of ten repetitions maximum with 2 min of rest between sets. Saliva sample 1 was collected at 0615 hours and resistance exercise began immediately afterwards at approximately 0620 hours, and sample 2 was collected at 0700 hours, which corresponded approximately to a mid-exercise (or control) time point. Saliva samples were then obtained every hour on the hour from 0800 hours until 2200 hours. No significant differences were observed between the exercise and resting conditions for salivary testosterone, with the exception of a significant decrease at 0700 hours during the resistance exercise protocol. The results of this investigation indicate that resistance exercise does not affect the circadian pattern of salivary testosterone secretion over a 16-h waking period in resistance-trained men.
    Arbeitsphysiologie 01/2001; 84(1-2):13-8. · 2.15 Impact Factor
  • Article: INFLUENCE OF SUPERVISION OF STRENGTH TRAINING ON TESTOSTERONE: CORTISOL RATIO
    Medicine and Science in Sports and Exercise - MED SCI SPORT EXERCISE. 01/2001; 33(5).
  • Article: No effect of heavy resistance training and creatine supplementation on blood lipids.
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    ABSTRACT: In order to examine the effects of heavy resistance training and the influence of creatine supplementation on nonperformance measures of health status, 19 healthy resistance-trained men were matched and then randomly assigned in a double-blind fashion to either a creatine (n = 10) or placebo (n = 9) group. Periodized heavy resistance training was performed 3-4 times per week for 12 weeks. During the first week of training, creatine subjects consumed 25 g creatine monohydrate per day, while the placebo group ingested an equal number of placebo capsules. Five grams of supplement per day was consumed for the remainder of the study. Body composition, fasting serum creatinine, lipoproteins and triglycerides, and reported changes in body function were determined prior to and after 12 weeks of training and supplementation. After training, significant increases in body mass and fat-free mass were greater in creatine (5.2 and 4.3 kg, respectively) than placebo (3.0 and 2.1 kg, respectively) subjects. There was no change in percent body fat. Dietary energy and macronutrient distribution was not significantly different during Weeks 1 and 12. Serum creatinine was significantly elevated in creatine subjects after 1 (11.6%) and 12 weeks (13.8%); however, values were within normal limits for healthy men. There were no effects of training or supplementation on serum total cholesterol, HDL-cholesterol, LDL-cholesterol, or triglycerides. In healthy men, a 12-week heavy resistance training program, with or without creatine supplementation, did not significantly influence serum lipid profiles, subjective reports of body functioning, or serum creatinine concentrations.
    International journal of sport nutrition and exercise metabolism 07/2000; 10(2):144-56. · 2.01 Impact Factor
  • Article: The influence of direct supervision of resistance training on strength performance.
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    ABSTRACT: The purpose of this study was to compare changes in maximal strength, power, and muscular endurance after 12 wk of periodized heavy-resistance training directly supervised by a personal trainer (SUP) versus unsupervised training (UNSUP). Twenty moderately trained men aged 24.6 +/- 1.0 yr (mean +/- SE) were randomly assigned to either the SUP group (N = 10) or the UNSUP group (N = 8). Both groups performed identical linear periodized resistance training programs consisting of preparatory (10-12 repetitions maximum (RM)), hypertrophy (8 to 10-RM), strength (5 to 8-RM), and peaking phases (3 to 6-RM) using free-weight and variable-resistance machine exercises. Subjects were tested for maximal squat and bench press strength (1-RM), squat jump power output, bench press muscular endurance, and body composition at week 0 and after 12 wk of training. Mean training loads (kg per set) per week were significantly (P < 0.05) greater in the SUP group than the UNSUP group at weeks 7 through 11 for the squat, and weeks 3 and 7 through 12 for the bench press exercises. The rates of increase (slope) of squat and bench press kg per set were significantly greater in the SUP group. Maximal squat and bench press strength were significantly greater at week 12 in the SUP group. Squat and bench press 1-RM, and mean and peak power output increased significantly after training in both groups. Relative local muscular endurance (80% of 1-RM) was not compromised in either group despite significantly greater loads utilized in bench press muscular endurance testing after training. Body mass, fat mass, and fat-free mass increased significantly after training in the SUP group. Directly supervised, heavy-resistance training in moderately trained men resulted in a greater rate of training load increase and magnitude which resulted in greater maximal strength gains compared with unsupervised training.
    Medicine &amp Science in Sports &amp Exercise 06/2000; 32(6):1175-84. · 4.43 Impact Factor
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    Article: Performance and muscle fiber adaptations to creatine supplementation and heavy resistance training.
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    ABSTRACT: The purpose of this study was to examine the effect of creatine supplementation in conjunction with resistance training on physiological adaptations including muscle fiber hypertrophy and muscle creatine accumulation. Nineteen healthy resistance-trained men were matched and then randomly assigned in a double-blind fashion to either a creatine (N = 10) or placebo (N = 9) group. Periodized heavy resistance training was performed for 12 wk. Creatine or placebo capsules were consumed (25 g x d(-1)) for 1 wk followed by a maintenance dose (5 g x d(-1)) for the remainder of the training. After 12 wk, significant (P < or = 0.05) increases in body mass and fat-free mass were greater in creatine (6.3% and 6.3%, respectively) than placebo (3.6% and 3.1%, respectively) subjects. After 12 wk, increases in bench press and squat were greater in creatine (24% and 32%, respectively) than placebo (16% and 24%, respectively) subjects. Compared with placebo subjects, creatine subjects demonstrated significantly greater increases in Type I (35% vs 11%), IIA (36% vs 15%), and IIAB (35% vs 6%) muscle fiber cross-sectional areas. Muscle total creatine concentrations were unchanged in placebo subjects. Muscle creatine was significantly elevated after 1 wk in creatine subjects (22%), and values remained significantly greater than placebo subjects after 12 wk. Average volume lifted in the bench press during training was significantly greater in creatine subjects during weeks 5-8. No negative side effects to the supplementation were reported. Creatine supplementation enhanced fat-free mass, physical performance, and muscle morphology in response to heavy resistance training, presumably mediated via higher quality training sessions.
    Medicine &amp Science in Sports &amp Exercise 09/1999; 31(8):1147-56. · 4.43 Impact Factor
  • Article: Resistance training and elite athletes: adaptations and program considerations.
    W J Kraemer, N D Duncan, J S Volek
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    ABSTRACT: The skepticism surrounding the potential benefits of resistance exercise training prevalent just decades ago has evolved over the years to an understanding of the integral nature muscular overload plays in the training programs for athletes. The science of training elite athletes is progressing rapidly, as insights into the physiological adaptations resulting from varying program configurations become available. Resistance training impacts several body systems, including muscular, endocrine, skeletal, metabolic, immune, neural, and respiratory. An understanding and appreciation of basic scientific principles related to resistance training is necessary in order to optimize training responses. Careful selection of the acute program variables in a workout to simulate sports-specific movements is required for optimal transfer of gains made in training to competition. Thus, whether athletes require predominantly eccentric, isometric, slow-velocity, or high-velocity strength or power in their athletic event will dictate the time commitment to each component and form the basis for designing individual workouts. Program variation over a training period is essential to maximize gains and prevent overtraining.
    Journal of Orthopaedic and Sports Physical Therapy 09/1998; 28(2):110-9. · 3.00 Impact Factor
  • Article: The effect of heavy resistance exercise on the circadian rhythm of salivary testosterone in men
    European journal of applied physiology. 84(1):13-18.
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    Article: Influence of a compression garment on repetitive power output production before and after different types of muscle fatigue
    Research in Sports Medicine: An International Journal. 8(2):163-184.