M. L. Pollock’s research while affiliated with University of Wisconsin - Milwaukee and other places

IntroductionPhysiological and pathological changes related to ageing and exercise scienceExercise in preventive geriatricsSpecial concerns related to medical clearence of exerciseEffects of endurance training in the elderlyExercise prescription in the elderlyConsulionsRefernces

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.

Deterioration in left ventricular function is a more sensitive marker of myocardial ischemia during exercise than ST segment depression. The current study was designed to evaluate left ventricular function during one-repetition-maximum (1-RM) strength testing and resistance exercise in cardiac patients with moderate left ventricular dysfunction. Using echocardiographic methods, left ventricular function was evaluated in 15 patients with left ventricular dysfunction (age, 65 +/- 6.5 years; ejection fraction, 42.1 +/- 5.8). Measurements were performed during 1-RM testing and resistance exercise (20%, 40%, and 60% of 1-RM using 10 to 15 repetitions) on the one-arm biceps curl (BIC) and bilateral knee extension exercises and compared with measurements of left ventricular function during the symptom-limited graded exercise test (SL-GXT). During the knee extension exercise, there was a slight but significant reduction (P< or =.05) in ejection fraction values at the end of 60% 1-RM, as compared with rest and previous workloads. Significant increases in systolic blood pressure and left ventricular end-systolic volume ratio values (P< or =.05) from rest to exercise were observed across test modes and for all workloads. The prevalence of new wall motion abnormalities during knee extension and BIC 1-RM strength testing was comparable with that observed during SL-GXT. The greatest increase in new wall motion abnormalities was seen during 60% 1-RM of knee extension exercise, as compared with prior workloads, BIC exercises, and SL-GXT. Despite an increase in occurrence of ischemic changes during the highest resistance exercise workloads and with larger muscle mass, the findings are small in magnitude and do not suggest reduced cardiac performance.

A group of 26 sedentary adults [mean age 48.4 (SD 6.4) years] were allocated randomly into either a non-exercising control group (CON, n =9) or an exercise group (EX, n = 17) that trained 3 days a week for 12 weeks using a total body recumbent stepper (TBRS). Training intensity and duration progressed from 50% of heart rate reserve maximum (HRRmax) for 20 min to 75% HRRmax for 40 min. Maximal exercise responses were measured during incremental treadmill (TM) and TBRS tests to examine the specificity of the adaptations to training. Muscle strength was measured using a one repetition maximum (1 RM) test for the leg press (LP), chest press (CP), and seated row (SR). Muscle endurance (END) was evaluated for LP, CP, and SR as the number of repetitions achieved before failure when exercising at an intensity of 60% of baseline 1 RM. Body composition was estimated using the sum of seven skinfolds. After training, significant increases (P < 0.05) in maximal oxygen uptake and exercise time were observed in the EX group on both the TM (9.3% and 4.8%, respectively) and TBRS (18.2% and 70.5%, respectively). The TBRS training resulted in significant increases (P < 0.01) in 1 RM and END of the legs, chest, and back, with greater magnitude of improvements observed for END. Furthermore, TBRS training resulted in a significant increase in lean body mass and significant reductions in fat mass and percentage body fat (P<0.01). The CON did not show changes in any measurement (P>0.05). These data indicated concurrent improvements in both cardiovascular and muscle fitness. The greater improvements observed on the TBRS test and in muscle endurance suggest the adaptations are specific to the mode of training.

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. 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. 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. These findings indicate that increased circulating IGF-I may, at least in part, mediate increases in strength that result from resistance training.

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 . wk(-1) program in which they performed single-set resistance training (I-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 (I-RM) far 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 I-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.

Studies have shown that digoxin binds to the working muscles during an acute bout of exercise, with a concomitant decrease in serum digoxin concentration. This study investigated the effects of 16 weeks of endurance exercise training on the pharmacokinetics of digoxin in old and young adults. Twelve subjects, aged 68.5 +/- 4.5 years, and six subjects, aged 30.3 +/- 3.8 years, completed the study. All subjects were healthy, sedentary, and taking no cardiovascular medications. After initial testing and maximum oxygen consumption (VO2max) measurements, subjects were hospitalized for 28 hours for renal function testing and digoxin clearance studies and then randomly assigned to an exercise (EG) or control (CG) group. The EG completed 16 weeks (three 1-hour bouts/week) of aerobic training at 75% to 85% of maximum capacity. The CG did not exercise. All tests were repeated at the end of the 16-week study period. In the older EG subjects, VO2max increased by 3.4 ml/kg/min, or approximately 16% (P = 0.0002). VO2max increased in the younger EG subjects by 1.1 ml/kg/min, but the increase was not significant (P > 0.05). There were no significant changes in body composition, renal function, or time of onset, peak concentration, or elimination phase half-life of digoxin in either the old or young exercise or control groups (P > 0.05 for all variables). Although 16 weeks of endurance exercise training improves cardiorespiratory fitness, the pharmacokinetics of digoxin are neither improved nor adversely affected in healthy old and young adults.

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.