Biomedical subjects

Edward P Hebert

Publications and source records attributed to Edward P Hebert.

4 recordsLinked to original sources

PubMed2003

Hormonal responses from concentric and eccentric muscle contractions.

UNLABELLED: Intense resistance exercise can acutely increase testosterone (T), free testosterone (FT), and growth hormone (GH) concentrations, but there are few investigations concerning acute endocrine responses to concentric (CON) and eccentric (ECC) contractile actions. PURPOSE: The purpose of the study was to compare acute anabolic hormonal responses to bouts of dynamic CON and ECC contractions from multiple exercises at the same absolute load. METHODS: Ten young men (age: 24.7 +/- 1.2 yr, weight: 85.45 +/- 24.2 kg, and height: 178 +/- 0.2 cm) completed two trials in counterbalanced fashion consisting of only CON or ECC contractions at the same absolute workload. Subjects performed four sets of 12 repetitions of bench press, leg extension, military press, and leg curl at 80% of a 10-repetition maximum with 90-s rest periods. Blood samples were collected pre-, post-, and 15-min postexercise. RESULTS: There were significant increases in GH, T, and FT and lactate for both trials, but only GH and lactate were greater for the CON trial. CONCLUSION: CON exercise increases GH concentrations to a much greater extent than ECC exercise at the same absolute load, and it is likely that greater GH responses were related to intensity rather than mode of contraction. Also, CON and ECC dynamic contraction trials at the same absolute workload elicited similar small but significant increases in T and FT, indicating that the greater metabolic stress produced by during the CON trial did not affect these hormone responses.

Adult↗

PubMed2003

RPE, pain, and physiological adjustment to concentric and eccentric contractions.

PURPOSE: The purpose of the study was to compare perceptual (RPE and pain), cardiac (heart rate), lactate, and endocrine (cortisol) responses with concentric (CON) and eccentric (ECC) resistance exercise protocols using the same absolute workload. METHODS: Eight healthy men with resistance-training experience participated in the study. Subjects completed two experimental trials consisting of either CON contractions or ECC contractions at the same absolute workload for each of four exercises: bench press, leg extension, military press, and leg curl. Subjects performed four sets of 12 repetitions at 80% of 10-RM with 90-s rest periods. Blood samples were taken before, immediately after, and 15-min postexercise. RESULTS: There was a significant trial effect for RPE, with CON exercise eliciting a higher RPE than ECC exercise (6.71 +/- 0.51 and 4.10 +/- 0.27, respectively). A significant trial effect was also demonstrated for pain, with CON exercise producing a higher pain rating than ECC exercise (5.59 +/- 0.41 and 3.23 +/- 0.27, respectively). Significantly higher heart rates and lactates were also demonstrated during the CON trial. For cortisol, a significant interaction was revealed between the pre- and immediate posttrial measures but not an overall trial effect. Correlational analyses revealed a significant relationship between RPE and pain for both trials. CONCLUSIONS: CON exercise elicits greater perceptual (higher RPE and pain rating), cardiac, lactate and cortisol response than ECC exercise at the same absolute workload. Data demonstrate that relative to absolute load, RPE and pain respond to resistance exercise in a similar fashion. Additionally, physiological cues are consistent with these perceptual data.

Adolescent↗

PubMed2003

Adiponectin responses to continuous and progressively intense intermittent exercise.

PURPOSE: Adiponectin is a recently discovered adipocyte protein that is lower in patients with coronary artery disease and in Type II diabetics who have insulin resistance. Regular exercise is known to be a preventative factor in the development of atherosclerosis and Type II diabetes. Acute exercise increases insulin sensitivity; however, it also increases beta-adrenergic and glucocorticoid activities that may suppress adiponectin expression. Two experiments were conducted to determine whether acute exercise affects adiponectin concentrations. METHODS: In the first experiment, six healthy male subjects completed 30 min of heavy continuous running exercise at 79% of VO (2max). In the second experiment, well-trained runners completed strenuous intermittent exercise consisting of treadmill running at 60, 75, 90, and 100% VO (2max). A resting control trial for the second experiment was also conducted. RESULTS: Glucose and insulin were not altered significantly in the first experiment, but both increased significantly (P < 0.05) in the second experiment. A significant increase (P < 0.05) in adiponectin in the first experiment was no longer significant after correction for plasma volumes shifts. In the second experiment, there were significant (P < 0.05) changes in adiponectin concentrations over time but not a significant difference between adiponectin responses in exercise and control trials. CONCLUSIONS: The data suggest that 30 min of heavy continuous running or more strenuous intermittent running does not stimulate an increase in production and release of adiponectin, and small increases in adiponectin concentrations resulting from the exercise may be attributed to normal plasma volume shifts.

Adiponectin↗

PubMed2003

Different effects of concentric and eccentric muscle actions on plasma volume.

The effects of concentric (CON) and eccentric (ECC) contractions on Delta plasma volume (PV), heart rate (HR), and lactate in responses to protocols in different body positions were investigated. CON or ECC contractions were performed in either a single-exercise (6 sets of 12 repetitions of leg extensions completed at 80% of 12 repetition maximum [12RM] with 3-minute rest periods) or multiexercise (4 sets of 10 repetitions for both CON and ECC trials of bench press, leg extension, military press, and leg curl at 80% of 10RM with 90-second rest periods) protocols. HR and lactate increased significantly for both protocols from pre- to postexercise for CON but not ECC trials. DeltaPV was greater following both CON single-exercise (-11.48 +/- 1.38%) and multiexercise (-4.64 +/- 0.33%) trials vs. ECC single-exercise (-1.62 +/- 1.69%) and multiexercise (-1.26 +/- 1.20) trials. Data demonstrate ECC exercise in response to single and multiexercise protocols at the same absolute workload as CON exercise produces less cardiovascular stress.

Adult↗