L. Garzarella

Time course for strength and muscle thickness changes following upper and lower body resistance training in men and women.

Abstract The purpose of this study was to investigate the time course of skeletal muscle adaptations resulting from high-intensity, upper and lower body dynamic resistance training (WT). A group of 17 men and 20 women were recruited for WT, and 6 men and 7 women served as a control group. The WT group performed six dynamic resistance exercises to fatigue using 8–12 repetition maximum (RM). The subjects trained 3 days a week for 12 weeks. One-RM knee extension (KE) and chest press (CP) exercises were measured at baseline and at weeks 2, 4, 6, 8, and 12 for the WT group. Muscle thickness (MTH) was measured by ultrasound at eight anatomical sites. One-RM CP and KE strength had increased significantly at week 4 for the female WT group. For the men in the WT group, 1 RM had increased significantly at week 2 for KE and at week 6 for CP. The mean relative increases in KE and CP strength were 19% and 19% for the men and 19% and 27% for the women, respectively, after 12 weeks of WT. Resistance training elicited a significant increase in MTH of the chest and triceps muscles at week 6 in both sexes. There were non-significant trends for increases in quadriceps MTH for the WT groups. The relative increases in upper and lower body MTH were 12%–21% and 7%–9% in the men and 10%–31% and 7%–8% in the women respectively, after 12 weeks of WT. These results would suggest that increases in MTH in the upper body are greater and occur earlier compared to the lower extremity, during the first 12 weeks of a total body WT programme. The time-course and proportions of the increase in strength and MTH were similar for both the men and the women.

Effects of resistance training on insulin-like growth factor-I and IGF binding proteins.

PURPOSE Our goal was to determine the effects resistance training on circulating IGF-I and on two of its major binding proteins, IGFBP-1 and IGFBP-3. Additional goals were to compare the time course of hormonal changes with the time course of strength changes and to determine the effect of training volume on the extent of hormonal changes. METHODS Thirty-one men and women (mean age = 37 +/- 7 yr) completed a 25-wk, 3 d x wk(-1) program in which they performed single-set resistance training (1-SET, N = 11), multiple-set resistance training (3-SET, N = 11), or no exercise (Control, N = 9). Before training, and after 13 and 25 wk of training, blood hormones were analyzed and strength was assessed as the sum of one-repetition maximum (1-RM) for leg extension and chest press exercises. RESULTS During the first 13 wk of resistance training, circulating IGF-I increased by approximately 20% in both the 1-SET and 3-SET groups (P = 0.041). No further increases occurred between 13 and 25 wk. In the 3-SET group, IGFBP-3 decreased 20% between 13 and 25 wk (P = 0.008). Training did not alter IGFBP-1. Increases in 1-RM strength occurred mainly during the first 13 wk of training and were significantly higher with 3-SET training compared to 1-SET. CONCLUSIONS These findings indicate that increased circulating IGF-I may, at least in part, mediate increases in strength that result from resistance training.

Single versus multiple sets in long-term recreational weightlifters

PURPOSE The purpose of this study was to determine the effects of increasing training volume from one set to three sets on muscular strength, muscular endurance, and body composition in adult recreational weight lifters. METHODS Forty-two adults (age 39.7 +/- 6.2 yr; 6.2 +/- 4.6 yr weight training experience) who had been performing one set using a nine-exercise resistance training circuit (RTC) for a minimum of 1 yr participated in this study. Subjects continued to perform one set (EX-1; N = 21) or performed three sets (EX-3; N = 21) of 8-12 repetitions to muscular failure 3 d x wk(-1) for 13 wk using RTC. One repetition maximums (1-RM) were measured for leg extension (LE), leg curl (LC), chest press (CP), overhead press (OP), and biceps curl (BC). Muscular endurance was evaluated for the CP and LE as the number of repetitions to failure using 75% of pretraining 1-RM. Body composition was estimated using the sum of seven skinfold measures. RESULTS Both groups significantly improved muscular endurance and 1 RM strength (EX-1 by: 13.6% LE; 9.2% LC; 11.9% CP; 8.7% OP; 8.3% BC; and EX-3 by: 12.8% LE; 12.0% LC; 13.5% CP; 12.4% OP; 10.3% BC) (P < 0.05). Both groups significantly improved lean body mass (P < 0.05). No significant differences between groups were found for any of the test variables (P > 0.05). CONCLUSION Both groups significantly improved muscular fitness and body composition as a result of the 13 wk of training. The results show that one-set programs are still effective even after a year of training and that increasing training volume over 13 wk does not lead to significantly greater improvements in fitness for adult recreational weight lifters.

Cross-Validation of the YMCA Submaximal Cycle Ergometer Test to Predict VO2max

Abstract Maximal oxygen uptake (VO2max) is an important indicator of health-risk status, specifically for coronary heart disease (Blair et al., 1989). Direct measurement of VO2max is considered to be the most accurate means of determining cardiovascular fitness level. Typically, this measurement is taken using a progressive exercise test on a treadmill or cycle ergometer. Unfortunately, this test is costly and time consuming and requires a well equipped laboratory, highly trained personnel, and for some populations medical supervision. Therefore, submaximal exercise test protocols that predict VO2max have been developed (Astrand & Rhyming, 1954; Fitchett, 1985). These tests require less equipment, time and are easily administered without highly skilled personnel.

Isometric torso rotation strength: Effect of training frequency on its development

OBJECTIVE To examine training frequencys effect on torso rotation muscle strength. DESIGN The study followed a pretest-posttest randomized-group design. SETTING University laboratory. PATIENTS Subjects, 33 men (age 30 +/- 11yr) and 25 women (age 28 +/- 10yr) with no history of low back pain, volunteered to participate in the study and were tested for isometric (IM) torso rotation strength before (T1) and after (T2) 12 weeks of training. Measurements of maximal voluntary IM torso rotation torque (N.m) were made through a 108 degrees range of motion (54 degrees, 36 degrees, 18 degrees, 0 degree, -18 degrees, -36 degrees, -54 degrees). Subjects were stratified by peak torque at T1, and randomized to a nonexercising control group (C, n = 10), or groups that trained once a week (1x/wk, n = 16), twice a week (2x/wk, n = 17), or three times a week (3x/wk, n = 15); and all groups were similar in strength. INTERVENTIONS Training consisted of 8 to 12 repetitions of full range dynamic variable resistance exercise to volitional fatigue, for both left and right rotation. MAIN OUTCOME To determine the best training frequency for the development of torso rotation strength. RESULTS Relative improvements (average increase in strength gained at each angle) for the training groups were 4.9%, 16.3%, and 11.9% for the 1, 2, and 3x/wk groups, respectively. The 1x/wk group did not increase in IM torso rotation strength compared to the control group at any angle. Both the 2 and 3x/ wk groups increased their IM torso rotation strength compared to the control group at all but one angle. There were no significant differences in IM torso rotation strength between the groups that trained 2 or 3x/wk. During the training period, the 2 and 3x/wk groups increased their dynamic training load significantly more than the 1x/wk group. CONCLUSIONS Posttraining dynamic strength was not different between training frequencies of 2 and 3x/wk. Therefore, training the rotary torso muscles 2x/wk is recommended.

The Lack of Effect of Aerobic Exercise Training on Propranolol Pharmacokinetics in Young and Elderly Adults

The effects of exercise training on the pharmacokinetics of orally administered propranolol were studied in young and elderly healthy volunteers. Twenty‐three young (30 ± 5 years of age) and 20 elderly (67 ± 5 years of age) adults were randomly assigned to endurance training (N = 12 young subjects, 10 elderly subjects) or nonexercising control (N = 11 young subjects, 10 elderly subjects) groups. Training consisted of treadmill walking, stairclimbing, or both three times per week for 40 minutes at 70–85% of maximal heart rate reserve for 16 weeks. Resting plasma propranolol concentrations after a single dose of 80 mg of oral propranolol were measured by high performance liquid chromatography with fluorescence detection, and estimated hepatic blood flow measured was measured using indocyanine green during supine rest. Aerobic training increased maximal oxygen uptake (VO2 max) by 13% and 14% in the exercising young and elderly groups, respectively. There was no change in VO2 max in either control group. Adjusted mean estimated hepatic blood flow after exercise corrected for body weight for the young subjects who did not exercise (15.6 mL/min/Kg) and those who did (18.2 mL/min/Kg) groups were of borderline significance. No statistical differences were detected in the experimental propranolol pharmacokinetic parameters (maximal concentration, time of maximal concentration, terminal half‐life, area under the curve, and protein binding) or derived pharmacokinetic parameters (intrinsic clearance, bioavailability, clearance, and volume of distribution). These results provide evidence that changes in aerobic fitness do not produce corresponding changes in propranolol pharmacokinetics in young or elderly adults.

Type 1 and type 2 diabetes mellitus in childhood in the United States: practice patterns by pediatric endocrinologists.

AIM To determine the relative frequency of type 2 diabetes mellitus (DM) in the US, and to assess diabetes practice patterns in the US. METHOD A questionnaire regarding pediatric diabetes practice patterns was distributed to the members of the Lawson Wilkins Pediatric Endocrine Society in 1999. Only one member of each practice group was requested to respond. Responses received through early 2000 were analyzed. RESULTS One hundred and twenty-six practices representing 45% of the members of the Society responded. 11.9% of pediatric patients with DM were considered to have type 2 DM. On average 53 new patients with DM were seen each year. The average practice consisted of 2.5 physicians, 1.5 nurse educators, 1.3 dieticians, 1.0 social workers and 0.5 nurse practitioners. Management practices comply by and large with the recommendations of the American Diabetes Association and reflect a trend toward more intensive treatment and monitoring. CONCLUSION Type 2 DM was seen in 11.9% of patients. Most diabetes practices in the US utilize a team approach to the management of youth with DM.

Exercise training in older men and women: Effects on cardiovascular and renal function

This study investigated the effects of endurance exercise training on cardiovascular and renal function in healthy, older adults. Twenty-three sedentary men and women, 68.2 ± 4.6 (mean ± SD) years of age completed medical screening, including ECG studies and serum chemistries, graded exercise testing, maximal oxygen uptake (VO2max) determinations, and renal function testing prior to being randomly assigned to an exercise group (EG, n = 13), or to a non-exercising control group (CG, n = 10). The EG completed 16 weeks (3-bouts · wk−1) of supervised exercise training on treadmills and stair-climbers, progressing in intensity from 50% to 85% of maximal heart rate reserve. Effective renal plasma flow (ERPF) and glomerular filtration rate (GFR) were measured by single-bolus I.V. radioisotope injections, VO2max was measured during maximum exercise testing. The EG showed a significant increase in VO2max (from 21.8 ml · kg−1 min−1 to 26.0 ml · kg−1 · min−1; p = 0.0009), while the CG showed no change (p = 0.05). There were no significant changes in ERPF or GFR in either group after the 16-wk training or control periods (p > 0.05). These data suggest that although endurance exercise training improves cardiorespiratory function in older adults, renal function is neither improved nor adversely affected.