CiteULike: omalbams excercise

The effects of supraphysiologic doses of testosterone on muscle size and strength in normal men.

S Bhasin — 2008-01-27T19:10:40-00:00

N Engl J Med, Vol. 335, No. 1. (4 July 1996), pp. 1-7.

BACKGROUND: Athletes often take androgenic steroids in an attempt to increase their strength. The efficacy of these substances for this purpose is unsubstantiated, however. METHODS: We randomly assigned 43 normal men to one of four groups: placebo with no exercise; testosterone with no exercise; placebo plus exercise; and testosterone plus exercise. The men received injections of 600 mg of testosterone enanthate or placebo weekly for 10 weeks. The men in the exercise groups performed standardized weight-lifting exercises three times weekly. Before and after the treatment period, fat-free mass was determined by underwater weighing, muscle size was measured by magnetic resonance imaging, and the strength of the arms and legs was assessed by bench-press and squatting exercises, respectively. RESULTS: Among the men in the no-exercise groups, those given testosterone had greater increases than those given placebo in muscle size in their arms (mean [+/-SE] change in triceps area, 424 +/- 104 vs. -81 +/- 109 square millimeters; P < 0.05) and legs (change in quadriceps area, 607 +/- 123 vs. -131 +/- 111 square millimeters; P < 0.05) and greater increases in strength in the bench-press (9 +/- 4 vs. -1 +/- 1 kg, P < 0.05) and squatting exercises (16 +/- 4 vs. 3 +/- 1 kg, P < 0.05). The men assigned to testosterone and exercise had greater increases in fat-free mass (6.1 +/- 0.6 kg) and muscle size (triceps area, 501 +/- 104 square millimeters; quadriceps area, 1174 +/- 91 square millimeters) than those assigned to either no-exercise group, and greater increases in muscle strength (bench-press strength, 22 +/- 2 kg; squatting-exercise capacity, 38 +/- 4 kg) than either no-exercise group. Neither mood nor behavior was altered in any group. CONCLUSIONS: Supraphysiologic doses of testosterone, especially when combined with strength training, increase fat-free mass and muscle size and strength in normal men.

Physical Activity and Mortality: Is the Association Explained by Genetic Selection?

Sofia Carlsson — 2008-01-08T22:34:30-00:00

Am. J. Epidemiol., Vol. 166, No. 3. (1 August 2007), pp. 255-259.

Public health recommendations promote physical activity to improve health and longevity. Recent data suggest that the association between physical activity and mortality may be due to genetic selection. Using data on twins, the authors investigated whether genetic selection explains the association between physical activity and mortality. Data were based on a postal questionnaire answered by 13,109 Swedish twin pairs in 1972. The national Cause of Death Register was used for information about all-cause mortality (n = 1,800) and cardiovascular disease mortality (n = 638) during 1975-2004. The risk of death was reduced by 34% for men (relative risk = 0.64, 95% confidence interval: 0.50, 0.83) and by 25% for women (relative risk = 0.75, 95% confidence interval: 0.50, 1.14) reporting high physical activity levels. Within-pair comparisons of monozygotic twins showed that, compared with their less active co-twin, the more active twin had a 20% (odds ratio = 0.80, 95% confidence interval: 0.65, 0.99) reduced risk of all-cause mortality and a 32% (odds ratio = 0.68, 95% confidence interval: 0.49, 0.95) reduced risk of cardiovascular disease mortality. Results indicate that physical activity is associated with a reduced risk of mortality not due to genetic selection. This finding supports a causal link between physical activity and mortality. 10.1093/aje/kwm132

Effects of aerobic training, resistance training, or both on glycemic control in type 2 diabetes: a randomized trial.

RJ Sigal — 2008-01-07T18:22:03-00:00

Ann Intern Med, Vol. 147, No. 6. (18 September 2007), pp. 357-369.

BACKGROUND: Previous trials have evaluated the effects of aerobic training alone and of resistance training alone on glycemic control in type 2 diabetes, as assessed by hemoglobin A1c values. However, none could assess incremental effects of combined aerobic and resistance training compared with either type of exercise alone. OBJECTIVE: To determine the effects of aerobic training alone, resistance training alone, and combined exercise training on hemoglobin A1c values in patients with type 2 diabetes. DESIGN: Randomized, controlled trial. SETTING: 8 community-based facilities. PATIENTS: 251 adults age 39 to 70 years with type 2 diabetes. A negative result on a stress test or clearance by a cardiologist, and adherence to exercise during a 4-week run-in period, were required before randomization. Interventions: Aerobic training, resistance training, or both types of exercise (combined exercise training). A sedentary control group was included. Exercise training was performed 3 times weekly for 22 weeks (weeks 5 to 26 of the study). MEASUREMENTS: The primary outcome was the change in hemoglobin A1c value at 6 months. Secondary outcomes were changes in body composition, plasma lipid values, and blood pressure. RESULTS: The absolute change in the hemoglobin A1c value in the combined exercise training group compared with the control group was -0.51 percentage point (95% CI, -0.87 to -0.14) in the aerobic training group and -0.38 percentage point (CI, -0.72 to -0.22) in the resistance training group. Combined exercise training resulted in an additional change in the hemoglobin A1c value of -0.46 percentage point (CI, -0.83 to -0.09) compared with aerobic training alone and -0.59 percentage point (CI, -0.95 to -0.23) compared with resistance training alone. Changes in blood pressure and lipid values did not statistically significantly differ among groups. Adverse events were more common in the exercise groups. LIMITATIONS: The generalizability of the results to patients who are less adherent to exercise programs is uncertain. The participants were not blinded, and the total duration of exercise was greater in the combined exercise training group than in the aerobic and resistance training groups. CONCLUSION: Either aerobic or resistance training alone improves glycemic control in type 2 diabetes, but the improvements are greatest with combined aerobic and resistance training. ClinicalTrials.gov registration number: NCT00195884. CRITICAL APPRAISSAL This is a superb randomized trial of two different types of exercise, or their combination on glycemic control and weight in diabetic patients. It randomized approximately 240 patients to aerobic exercise, resistance exercise (weights), the combination vs. standard therapy (control). It showed that aerobic exercise had a positive effect on HgbA1c, compared with control, and weight training had an intermedicate effect, and the combination of both aerobic and weight training had the best effect. Weight followed the same pattern. Hbg A1c was reduced by nearly 1% (absolute) with the combination approach. Weight fell about 2-2.5 kg with exercise. This helps me recommend a combination approach for my patients (diabetic or not) - and for myself! Christopher Cannon, MD