Effects of high-intensity resistance training on untrained older men. I. Strength, cardiovascular, and metabolic responses.

Most resistance training studies of older subjects have emphasized low-intensity, short-term training programs that have concentrated on strength measurements. The purpose of this study was, in addition to the determination of strength, to assess intramuscular and transport factors that may be associated with strength increments. Eighteen untrained men ages 60-75 years volunteered for the study; 9 were randomly placed in the resistance-training group (RT), and the other half served as untrained (UT) or control subjects. RT subjects performed a 16-week high-intensity (85-90% 1 repetition maximum (RT]) resistance training program (2 x/wk) consisting of 3 sets each to failure (6-8 repetitions based on 1 RM of 3 exercises): leg press (LP), half squat (HS), and leg extension (LE) with 1-2 minutes rest between sets. Pre- and post- training strength was measured for the 3 training exercises using a 1 RM protocol. Body fat was calculated using a 3-site skinfold method. Biopsies from the vastus lateralis m. were obtained for fiber type composition, cross-sectional area, and capillarization measurements. Exercise metabolism, electrocardiography, and arterial blood pressure were observed continuously during a progressive treadmill test, and resting echocardiographic data were recorded for all subjects. Pre- and post-training venous blood samples were analyzed for serum lipids. Resistance training caused significant changes in the following comparisons: % fat decreased in the RT group by almost 3%, strength improved for all exercises: LE = + 50.4%, LP = + 72.3%, HS = + 83.5%; type IIB fibers decreased and IIA fibers increased; cross-sectional areas of all fiber types (I, IIA, IIB) increased significantly, and capillary to fiber ratio increased but not significantly. No differences were noted for ECG and echocardiographic data. The RT group significantly improved treadmill performance and VO2max. Pre- and post-training serum lipids improved but not significantly. No significant changes occurred in any pre- to post-tests for the UT group. The results show that skeletal muscle in older, untrained men will respond with significant strength gains accompanied by considerable increases in fiber size and capillary density. Maximal working capacity, VO2max, and serum lipid profiles also benefited from high-intensity resistance training, but no changes were observed for HR max, or maximal responses of arterial blood pressure. Older men may not only tolerate very high intensity work loads but will exhibit intramuscular, cardiovascular, and metabolic changes similar to younger subjects.

Cardiorespiratory and metabolic adaptations to hyperoxic training.

This study examined the effects of hyperoxic training on specific cardiorespiratory and metabolic responses. A group of 19 male subjects trained for 5 weeks on a cycle ergometer at 70 percent of hyperoxic or normoxic maximal heart rate, the hyperoxic group (HG) breathing 70 percent O2, the normoxic group (NG) breathing 21 percent O2. The subjects were tested pre- and post-training under both hyperoxia and normoxia. Measurements included cardiac output (Q(c)), stroke volume (SV), heart rate (HR), pulmonary ventilation (V(E)), oxygen consumption (VO(2)), partial pressure of oxygen (PO(2)), partial pressure of inspired carbon dioxide (PCO(2)), blood lactate concentration [La], and fiber type composition. The V(E) was significantly lower at submaximal work rates (P <0.05) and maximal V(E) increased after training in both groups for both test conditions; hyperoxic V(E) was lower than normoxic V(E) (P <0.05). The maximal V0(2) increased significantly (P <0.05) in both groups for both tests and was 11 percent - 12 percent higher during hyperoxia. Post-training maximal heart rate (HR(max)) was significantly decreased (P <0.05) at the same absolute work rate regardless of the training group or test type. The SV was increased at each work rate and Q c was unchanged. The maximal Q(c) increased significantly (P <0.05) for both groups and types of test: for normoxia: NG 27.3-30.41*min(-1) and HG 30.3-32.31*min(-1) and for hyperoxia: NG 24.7-25.6 and HG 27.9-31.21*min(-1). Although working at the same intensity relative to HR(max), HG showed significantly lower [La] following a single training session, yet maximal values were unchanged after training. Both groups showed a significant increase in the percentage of type IIA fibers post-training but HG retained a larger percentage of IIB fibers. Mitochondrial enzymes; citrate kinase, 3-hydroxyacyl CoA dehydrogenase, and cytochrome c-oxidase were increased in the normoxic trained subjects (P <0.05). In summary, training induced adaptive responses in maximal aerobic power, HR, SV, Q(c), [La], and muscle fiber type composition, independent of inspired PO(2). Intramuscular data suggested there may be some differences between hyperoxic and normoxic training and these were substantiated by mitochondrial enzyme and lactate findings. Our data would suggest that transport mechanisms may limit the ability to increase aerobic power.

Circadian rhythm of cortisol confounds cortisol responses to exercise: implications for future research.

To investigate whether measurements of cortisol responses to exercise are confounded by neglect of the hormone's circadian rhythm, we measured the serum and salivary cortisol responses of eight women to 40 min of 70% maximal oxygen consumption treadmill exercise beginning at 0800 and 2000. Responses were calculated relative to the usually employed preexercise concentrations and also to concentrations at the same times of another day while subjects were at rest. Compared with areas under response curves (AUCs) calculated relative to their circadian baselines, AUCs for serum and salivary cortisol calculated by reference to preexercise concentrations were underestimated (serum, P < 0.001; salivary, P < 0.01) by 93 and 84% in the morning and by 37 and 35% in the evening, respectively. Calculated by the usual preexercise baseline method, rises in serum and salivary cortisol were similarly underestimated. More accurately calculated relative to their circadian baselines, serum and salivary cortisol AUCs were similar (P = 0.63 and P = 0.37, respectively) in the morning and evening, as were their rises (P = 0.23 and P = 0.70, respectively). In future investigations of the existence and magnitude of cortisol responses, those responses must be calculated relative to the hormone's circadian baseline.

The effect of resistance training on blood pressure in normotensive women.

The purpose of the present study was to determine whether conventional resistance training alters 24-h ambulatory and manually determined casual blood pressure of normotensive women. Seven individuals (23 +/- 2 years old) trained 2 days week-1 for 20 weeks emphasizing the hip and knee extensor muscle groups. Three sets to exhaustion of the knee extension, squat, knee flexion and leg press exercises were performed. The load for each exercise represented approximately 80-85% of the one-repetition maximum. Average values for 24-h ambulatory blood pressure were not different (P greater than 0.05) pre- and post-training (systolic, 107 +/- 4 vs. 109 +/- 1 mmHg; diastolic, 73 +/- 2 vs. 71 +/- 2 mmHg). Ambulatory values over 8-h segments of the 24 h (day, evening, night) and casual resting determinations of blood pressure were also not affected. The lack of change in blood pressure cannot be explained by an insufficient training response. Knee extensor strength during dynamic or isokinetic actions increased (approximately 43%, P less than 0.05). In addition, biopsies from the vastus lateralis muscle showed an increase (P less than 0.05) in average muscle fibre cross-sectional area of 32%. This hypertrophic response was further substantiated by an increase (P less than 0.05) in lean body mass (41.2 +/- 1.3 kg to 43.4 +/- 1.5 kg). These results indicate that resistance training, which increases muscular strength, muscle fibre area and lean body mass, does not alter ambulatory or casual blood pressure. Thus, the concern that conventional resistance training may chronically elevate blood pressure does not appear warranted, at least in normotensive women.

Serum creatine kinase activity and its changes after a muscle biopsy.

The significance of the absolute elevations of serum creatine kinase (CK) levels after intense exercise and injuries was studied by measuring CK activities from seven healthy active males during a 2-week period, with a muscle biopsy taken between the first and second week. Most of the subjects (three lifters and two runners) carried on their normal exercise activities, while two lifters stopped training during the 2 weeks. The weight of the biopsy, number of fibres, percentage of fibre types, and cross-sectional areas of the muscle fibres were measured. The CK levels of the non-active subjects and runners remained consistently low during the control week, whereas those of the lifters were usually 500% greater than those of the other two groups, and fluctuated with the intensity of their workouts. A muscle biopsy, having a mean weight of 71.3 mg and containing 1800 fibres, increased the CK values by approximately 100 units litre-1 (U l-1) in most of the subjects. One runner injured his right hamstring muscles 2 days prior to the biopsy, and his CK values rose from 50 to 4400 U l-1. The increases in CK after the biopsy were not related to fibre type, activity, weight of the biopsy, or number or size of fibres removed. These results indicate that: (1) CK values are consistently lower in normal subjects and runners than in lifters. (2) Weight training results in chronic elevations of CK. (3) Compared to a muscle biopsy, muscular injury dramatically increases CK levels. (4) Elevation of serum CK is observed as early as 1 h after an intense weight-lifting session.(ABSTRACT TRUNCATED AT 250 WORDS)

Endurance training and blood pressure in normotensive and hypertensive adults.

Twenty-one male and female adults 43 +/- 4 yr of age completed in 8-wk control period, 16 wk of conditioning, and 12 wk of deconditioning to determine whether exercise alters blood pressure. Subjects were classified as borderline/mild hypertensive (H, diastolic pressure greater than or equal to 85 and less than 104 mm Hg, N = 8) or normotensive (N, diastolic pressure less than 85 mm Hg, N = 13) based on average blood pressure during the control period. Conditioning increased (P less than 0.05) VO2max to a similar extent in both groups (average, 14%) and decreased (P less than 0.05) resting heart rate (H, 78 +/- 5 to 65 +/- 3; N, 75 +/- 3 to 71 +/- 3 beats.min-1). The double product over 24 h of ambulatory monitoring of blood pressure and heart rate decreased (P less than 0.05) in both groups. After deconditioning, VO2max returned to values not different (P greater than 0.05) from those of the control period. Ambulatory 24-h double product and heart rate increased (P less than 0.05). In spite of this strong evidence of a conditioning effect, neither group showed changes (P greater than 0.05) in average 24-h ambulatory or casual blood pressure. The average ambulatory blood pressure for 8-h segments of the day (8 a.m.-4 p.m., 4 p.m.-12 a.m., and 12 a.m.-8 a.m.) was also not altered. Cardiac output and total peripheral resistance at rest did not change (P greater than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)