Biomedical subjects

A J Blazevich

Publications and source records attributed to A J Blazevich.

3 recordsLinked to original sources

PubMed2001

Effect of testosterone administration and weight training on muscle architecture.

PURPOSE: The purpose of this study was to assess muscle architecture changes in subjects who were administered supraphysiologic doses of testosterone enanthate (TE) and concurrently performed heavy resistance training. METHODS: Ten subjects were randomly selected from the 21 subjects who participated in a previously published study (12). Subjects were allocated to one of two groups as per Giorgi et al. (12) and received either a saline-based placebo (nonTE) or a 3.5-mg.kg-1 body weight dose of TE by deep intramuscular injection once a week for 12 wk. Subjects also performed heavy resistance training using exercises that targeted the triceps brachii muscle. Before and after the training period, free-weight one-repetition-maximum (1-RM) bench press strength was tested, muscle thickness and pennation of the triceps brachii lateralis were measured using ultrasound imaging, and fascicle length was estimated from ultrasound photographs. RESULTS: There were no significant between-group differences in muscle thickness changes despite a trend toward increased thickness in TE subjects (TE, 23.5%, vs nonTE, 13.8%). However, 1-RM bench press performance and muscle pennation increased significantly in TE subjects compared with nonTE subjects (P < 0.05). There was also a trend toward longer fascicle lengths in the muscles of nonTE subjects. CONCLUSION: The results of the present study suggest that the use of TE in conjunction with heavy resistance training is associated with muscle architecture changes that are commonly associated with high-force production. Since there was little difference between the groups in muscle thickness, changes in pennation and possibly fascicle length may have contributed to strength gains seen in TE subjects.

Adult↗

PubMed2000

Muscular and cardiorespiratory effects of pseudoephedrine in human athletes.

AIMS: Pseudoephedrine (PSE) is a readily available over-the-counter nasal decongestant which is structurally similar to amphetamine and is included on the International Olympic Committee's list of banned substances. However to date, little research has supported its putative ergogenic effect. This study investigated whether a 180 mg dose of PSE ingested 45 min prior to exercise enhanced short-term maximal exercise performance and/or altered related physiological variables. METHODS: A randomised, double-blind, crossover study in 22 healthy male athletes. RESULTS: Maximum torque (mean +/- s.d., n = 22) produced in an isometric knee extension exercise was 321.1+/-62.0 Nm (PSE) and 295.7+/-72.4 Nm (placebo), and peak power obtained on the 'all-out' 30 s cycle test was 1262.5+/-48.5 W (PSE) and 1228.4+/-47.1 W (placebo) (P<0.01, P<0.03, respectively). Subjects were estimated to be producing 96.9+/-2.4% of their maximal possible isometric leg extension force after PSE ingestion, but only 95.3+/-2.4% when PSE was not ingested. Bench press tasks and total work during the cycle test were not affected by the ingestion of PSE. Lung function was altered following ingestion of PSE (P<0.05) with FEV1 and FVC significantly increased (P<0.02, P<0.01, respectively) although the FEV1/FVC ratio was not altered. Heart rate was significantly elevated by the ingestion of PSE immediately following the 30 s cycle sprint (P<0.01) however, lactate concentration was not altered by the ingestion of PSE. CONCLUSIONS: The administration of a 180 mg dose of PSE increased maximum torque, produced in an isometric knee extension and produced an improvement in peak power during maximal cycle performance, as well as improving lung function.

Adolescent↗

PubMed1998

Physical performance differences between weight-trained sprinters and weight trainers.

The present study tested and compared well-trained athletes who were performing low-velocity, high-force resistance training and sprint running training (ST) when recruited, with subjects who were performing low-velocity, high-force resistance training but not sprint training (NST) when recruited. Eleven male sprint runners (mean +/- SD; age = 19.0 +/- 1.4 yr: height = 182.0 +/- 4.7 cm: mass = 75.7 +/- 4.7 kg), and eight male weight-trained athletes who were not currently performing sprint training, or any other additional training, (mean + SD; age = 21.5 +/- 1.8 yr: height = 184.5 +/- 3.6 cm: mass = 78.4 +/- 4.6 kg) participated in the study; all subjects had a minimum of two years resistance training experience. Tests included 1. running speed (20 m time after a 50 m acceleration distance and 20 m acceleration time from a stationary start), 2. isokinetic hip flexor/extensor torque (and torque adjusted for body mass), angle of peak torque, time to reach peak torque and torque acceleration energy at low (1.05 rad x s(-1) [60 degrees x s(-1)), moderate (4.74 rad x s(-1) [270 degrees x s(-1)) and high (8.42 rad x s(-1) [480 degrees x s(-1)) speeds and 3. maximum squat lift. ST subjects produced more isokinetic hip extensor torque when adjusted for body mass at 4.74 rad x s(-1) (270 degrees x s(-1); p<0.05) and reached their peak torque faster (p<0.05). ST subjects also produced more hip flexor torque at 8.42 rad x s(-1) (480 degrees x s(-1); p<0.05), and torque per body mass at 4.74 rad x s(-1) (270 degrees x s(-1)) and 8.42 rad x s(-1) (480 degrees x s(-1); p<0.05) and reached peak flexor torque faster than NST subjects (4.74 rad x s(-1) [270 degrees x s(-1)], p<0.05; 8.42 rad x s(-1) [480 degrees x s(-1), p<0.01). Further, ST subjects performed better in tests of running acceleration over 20 m (p<0.02) and achieved a higher maximum running velocity after a 50 m acceleration distance (p<0.001). No significant differences were found in isokinetic strength at low (1.05 rad x s(-1) [60 degrees x s(-1)) velocities or in maximal squat lift strength. The results of the present study suggest that athletes who perform low-velocity, high force training concurrently with high-velocity training are superior in tests of isokinetic strength at high velocities when compared to athletes who only perform low-velocity, high force training. This may be due to training or genetic factors.

Adult↗