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Biomedical subjects

A Weltman

Publications and source records attributed to A Weltman.

At least 91 records · Page 5Linked to original sources
PubMed1987

Prediction of lactate threshold and fixed blood lactate concentrations from 3200-m running performance in male runners.

To determine the effectiveness of a 3200-m time trial for predicting VO2 and running velocity at lactate threshold (LT), fixed blood lactate concentrations of 2.0, 2.5, and 4.0 mM, and peak, 42 male runners (means age = 31.1 +/- 8.3 years; means ht = 176.8 +/- 6.6 cm; means wt = 70.4 +/- 10.0 kg) completed a VO2 peak/LT test and a 3200-m time trial. The continuous treadmill protocol started at 0% grade 150 m/min and increased 10 m/min every 3 min until exhaustion. Velocity at LT, 2.0, 2.5, and 4.0 mM was determined from individual velocity blood lactate relationships, and VO2 values were determined from individual plots ov VO2 vs velocity. VO2 peak and velocity peak were chosen as the highest values observed. Oxygen uptake at LT, 2.0, 2.5, 4.0 mM, and peak was 52.51, 56.61, 58.31, 61.70, and 64.21 ml/kg.min-1, respectively, while the velocities associated with LT, 2.0, 2.5, 4.0 mM, and peak were 235.5, 251.5, 259.8, 273.5, and 285.5 m/min, respectively. During the 3200-m time trial (means time = 11.28 +/- 0.96 min), 400-m split times and cumulative times were recorded. Twenty-nine subjects were randomly assigned to a validation sample and the remaining subjects were used for cross-validation purposes. Regression analysis revealed that a 3200-m time trial was a good predictor of both VO2 (ml/kg.min-1) and velocity (m/min) at LT, 2.0, 2.5, 4.0 mM, and peak.

Adult↗
PubMed1986

The effects of hydraulic resistance strength training in pre-pubertal males.

In order to examine the effectiveness and safety of hydraulic resistance strength training in young males, 26 pre-pubertal males (mean age = 8.2 +/- 1.3 yr) completed a 14-wk strength training study. Subjects were evaluated before and after the 14-wk experimental period for pubertal state (Tanner's sexual maturity rating, serum testosterone, and serum dihydroepiandrosterone sulfate). Effectiveness of the strength training program was determined by measuring pre-post differences in: isokinetic strength for flexion and extension at the knee and elbow joints at two speeds (30 degrees and 90 degrees X s-1) (KIN COM, Chattecx, Inc., Chattanooga, TN), flexibility, standing long jump, vertical jump, body composition parameters, maximal oxygen consumption, and creatinine phosphokinase. Safety of strength training was assessed by biphasic musculoskeletal scintigraphy before and after the program and by physician evaluation of complaints by subjects. Strength training subjects (N = 16) participated in a 45 min/session, 3 session/wk, 14-wk supervised strength training program with an attendance rate of 91.5%. Participants performed concentric work using hydraulic resistance equipment (Hydra-Fitness Industries, Belton, TX). Eccentric work was not performed. Control subjects (N = 10) did not strength train but did participate in sport activities and activities of daily living. Results indicated that strength training subjects increased isokinetic strength as a result of strength training (average concentric work/repetition increases by 18.5 to 36.6% for the eight motions tested; torque scores over the first 90% of the range of motion increases by 13.1 to 45.1% for the eight motions tested). These changes were significantly greater than changes seen in the control group (P less than 0.05). Strength training subjects also demonstrated significant improvements (as compared to control subjects) in vertical jump (+10.4%), flexibility (+8.4%), and maximal oxygen consumption [+19.4% (l X min-1), +13.8% (ml X kg X min-1)] after the experimental period. Musculoskeletal scintigraphy revealed no evidence of damage to epiphyses, bone, or muscle as a result of strength training. Only one strength training-related injury was reported (left shoulder pain, 3 strength training sessions missed). In contrast, six strength training subjects sustained injuries during activities of daily living, resulting in 47 missed strength training sessions. It was concluded that, in the short term, supervised concentric strength training using hydraulic resistance equipment is safe and effective in pre-pubertal boys.

Anthropometry↗
PubMed1985

Differential effects of exercise on serum lipid and lipoprotein levels seen with changes in body weight. A meta-analysis.

Ninety-five studies conducted between September 1955 and October 1983 measuring changes in human serum lipid and lipoprotein levels in response to exercise training were analyzed using meta-analysis. Change in body weight during exercise training may confound observed serum lipid and lipoprotein level changes; thus, data from these studies were partitioned into those where subjects gained body weight, maintained body weight, or lost body weight. Results showed differential changes in cholesterol, triglyceride, low-density lipoprotein-cholesterol (LDL-C), high-density lipoprotein-cholesterol, and cholesterol/high-density lipoprotein-cholesterol levels in the three body-weight categories. Where body weight did not change, cholesterol and LDL-C levels decreased significantly (7.3 mg/dL and 3.3 mg/dL, respectively). Where body weight decreased, cholesterol and LDL-C levels also decreased significantly (13.2 mg/dL and 11.1 mg/dL, respectively). However, with body-weight increase, cholesterol and LDL-C levels increased by 2.9 mg/dL and 3.0 mg/dL, respectively. These results suggest that reductions in cholesterol and LDL-C levels were greatest when exercise training was combined with body-weight losses.

Body Weight↗
PubMed1985

Effects of training at and above the lactate threshold on the lactate threshold and maximal oxygen uptake.

Thirty-three college women (mean age = 21.8 years) participated in a 5 d X wk-1, 12 week training program. Subjects were randomly assigned to 3 groups, above lactate threshold (greater than LT) (N = 11; trained at 69 watts above the workload associated with LT), = LT (N = 12; trained at the work load associated with LT) and control (C) (N = 10). Subjects were assessed for VO2max, VO2LT, VO2LT/VO2max, before and after training, using a discontinuous 3 min incremental (starting at 0 watts increasing 34 watts each work load) protocol on a cycle ergometer (Monark). Respiratory gas exchange measures were determined using standard open circuit spirometry while LT was determined from blood samples taken immediately following each work load from an indwelling venous catheter located in the back of a heated hand. Body composition parameters were determined before and after training via hydrostatic weighing. Training work loads were equated so that each subject expended approximately 1465 kJ per training session (Monark cycle ergometer) regardless of training intensity. Pretraining, no significant differences existed between groups for any variable. Post training the greater than LT group had significantly higher VO2max (13%), VO2LT (47%) and VO2LT/VO2max (33%) values as compared to C (p less than .05). Within group comparisons revealed that none of the groups significantly changed VO2max as a result of training, only the greater than LT group showed a significant increase in VO2LT (48%) (p less than .05), while both the = LT and greater than LT group showed significant increases in VO2LT/VO2max (= LT 16%, greater than LT 42% (p less than .05)).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1985

Effects of pedal frequency on VO2 and work output at lactate threshold (LT), fixed blood lactate concentrations of 2 mM and 4 mM, and max in competitive cyclists.

To determine the effects of differing pedal frequencies on VO2 and work output values at the lactate threshold (LT), fixed blood lactate concentrations of 2 mM and 4 mM (2 mM, 4 mM), and at max, nine male competitive road racing cyclists (USCF category I or II) completed three VO2 max tests; on a Monark bicycle ergometer, at pedal frequencies of 60, 90, and 120 rpm. Each stage was 3 min in duration, starting at 0 kgm/min with subsequent stages increased by either 180 kgm/min (60 and 120 rpm) or 178 kgm/min (90 rpm). Blood samples were taken during the last 30 s of each stage. VO2 and work output at LT, 2 mM, and 4 mM were determined from individual blood lactate-work rate and VO2-work rate relationships. VO2 max and maximal work output were chosen as the peak values observed during the VO2 max tests. Results indicated that work output at LT, 2 mM, and 4 mM was affected by choice of pedal frequency (1278, 1140, 999 kgm/min at LT; 1533, 1450, 1182 kgm/min at 2 mM; 1780, 1703, 1487 kgm/min at 4 mM; for 60, 90, and 120 rpm, respectively, P less than 0.05). Max work output at 60 and 90 rpm was significantly greater (P less than 0.05) than at 120 rpm (2035, 2053, 1879 kgm/min for 60, 90, and 120 rpm, respectively).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1985

Prediction of maximal effort bicycle ergometer endurance performance.

Fifteen competitive cyclists and 15 subjects not involved in competitive cycling were studied to determine the relationship between VO2max, lactate threshold (LT), fixed blood lactate concentrations, body composition parameters, and maximal effort bicycle ergometer performance. The subjects were assessed for VO2max, LT, VOLT, and VO2 associated with blood lactate concentrations of 3, 4, 5, and 6 mM/l (VO2 3 mM-VO2 6 mM/l), using an incremental protocol on the bicycle ergometer. Body composition was determined by underwater weighing. Subjects also completed two 10-min drop-off performance tests (starting at 70 rpm) at the same absolute power output (4.5 kg resistance, 1890 kgm/min) (ABS) and at the same relative power output (the highest power output completed for 3 min on the VO2max test) (REL). Metabolic measures and revolution scores were collected on a minute-by-minute basis during the performance tests. The results indicated that the competitive cyclists had higher VO2max (4.25 +/- 0.39 vs 3.50 +/- 0.54 l/min); VO2 LT (2.91 +/- 0.55 vs 1.66 +/- 0.49 l/min); VO2 3 mM, VO2 4 mM, VO2 5 mM, VO2 6 mM, VO2 LT/VO2max (68.5 +/- 11.2 vs 47.2 +/- 10.9 %); max resistance (5.70 +/- 0.56 vs 4.63 +/- 0.67 kg); and resistance at LT (3.57 +/- 0.70 vs 1.93 +/- 0.68 kg) as compared to the noncompetitive subjects (P less than 0.05). Correlational analysis revealed poor prediction between metabolic measures and the homogeneous cumulative rpm scores during the REL test.2+ subjects (r = 0.60 to 0.90).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1985

Effects of physical training on cardiovascular fitness and behavior patterns of mentally retarded adults.

The effects of training on maximal oxygen consumption (VO2 max) and body weight of 5 mentally retarded adults were examined. These residents of an intermediate care facility volunteered to participate in a 23-week physical-training program. Supervised training sessions were held 4 to 6 days per week with attendance optional. Subjects were assessed for VO2 max and body weight changes before and after the training program. Results indicated that subjects attended the exercise sessions an average of 3.1 times per week and covered an average distance of 9.0 km/week. Their body weight was reduced by 3.6 kg and VO2 max increased 43%. Further favorable behavior changes occurred during the course of the physical training program.

Adult↗
PubMed1983

Prior exhaustive exercise and subsequent, maximal constant load exercise performance.

The effect of an elevated blood lactate concentration on maximal constant load exercise performance (MCLE) was studied in nine males. Two experimental sessions followed a continuous VO2max test, each consisting of an initial work bout at approximately 110% VO2max, a 20 min recovery, and a second maximal performance test. Blood lactate concentrations reached approximately 10 mM following the initial work bout and were altered prior to the second bout by one of two recovery patterns: 1) active recovery (AR)--pedaling at 40% VO2max or 2) passive recovery (PR)--sitting quietly. Performance time, total pedal revolutions, metabolic parameters, and heart rate (HR) were measured during each work bout. Despite significant differences in blood lactate concentration, there were no differences in work output among the performance tests (either between conditions or from pre- to post-recovery); there was a low correlation (r = 0.08) between pre-existing blood lactate concentration and work output on a subsequent maximal constant load exercise test. It was concluded that elevated blood lactate concentration does not affect maximal constant load exercise performance.

Adult↗
PubMed1983

The effects of exercise on blood lipids and lipoproteins: a meta-analysis of studies.

The results of 66 training studies involving the measurement of human blood lipid and lipoprotein changes over time, conducted over the last 26 yr, and representing 2925 subjects (2086 experimental and 839 control) were collected and statistically aggregated using the meta-analysis technique. Across all types of subjects, treatments, sources, and research designs, the average exercising subject was found to have a reduction in total cholesterol of 10 mg X dl-1 (P les than 0.01), total triglyceride decreased by 15.8 mg X dl-1 (P less than 0.01), DHL-C increased by 1.2 mg X dl-1 (NS), LDL-C decreased by 5.1 mg X dl-1 (P less than 0.05), and total/HDL-C ratio showed a large decrease of 0.48 (P less than 0.01). None of the changes for the control groups were significant. Initial levels of total cholesterol, total triglyceride, HDL-C, and total/HDL-C ratio were strongly correlated with their respective changes as a result of training, regardless of the data partitioning. Higher initial levels of total cholesterol, total triglyceride, and total/HDL-C ratio resulted in greater decreases post-exercise (r = 0.48, 0.76, and 0.75, respectively; P less than 0.01), and lower initial levels of HDL-C resulted in greater post-exercise increases (r = 0.50; P less than 0.01). Overall, physical training seemed to produce beneficial changes in blood lipids and lipoproteins. However, researchers must be careful when examining the relationship between physical training and serum lipids and lipoproteins because initial levels, age, length of training, intensity, VO2max, body weight, and percent body fat have been shown in this meta-analysis to interact with exercise and serum lipid and lipoprotein changes.

Age Factors↗
PubMed1981

Exercise recovery above and below anaerobic threshold following maximal work.

The purpose of this study was to determine the effects of resting and exercise recovery above [70% of maximum O2 uptake (VO2 max)] and below [40% of VO2 max] anaerobic threshold (AT) on blood lactate disappearance following maximal exercise. Blood lactate concentrations at rest (0.9 mM) and during exercise at 40% (1.3 mM) and 70% (3.5 mM) of VO2 max without preceding maximal exercise were determined on separate occasions and represented base lines for each condition. The rate of blood lactate disappearance from peak values was ascertained from single-component exponential curves fit for each individual subject for each condition using both the determined and resting base lines. When determined base lines were utilized, there were no significant differences in curve parameters between the 40 and 70% of VO2 max recoveries, and both were significantly different from the resting recovery. When a resting base line (0.9 mM) was utilized for all conditions, 40% of VO2 max demonstrated a significantly faster half time than either 70% of VO2 max or resting recovery. No differences were found between 70% of VO2 max and resting recovery. It was concluded that interpretation of the effectiveness of exercise recovery above and below AT with respect to blood lactate disappearance is influenced by the base-line blood lactate concentration utilized in the calculation of exponential half times.

Adult↗
PubMed1981

Comparison of hydrostatic weighing at residual volume and total lung capacity.

Hydrostatic weighing (HW) was performed at both residual volume (RV) and total lung capacity (TLC) (both measured on land) to determine if underwater weighting at extreme lung volumes affected the measurement of body density. Subjects were 72 middle-aged males (mean age = 43.4 yr) and 51 middle-aged females (mean age = 40.2 yr). Subjects were first assessed for underwater weight at RV for at least 10 trials. Subjects were than instructed to inspire maximally and hold their breath underwater for as long as they could. Three trials at TLC were used for assessment of underwater weight. Forced vital capacity and residual volume (oxygen dilution) were determined separately on land. Small but statistically significant differences in body density (Db) were observed with the use of RV (1.0354 g/ml for men and 1.0196 g/ml for women) vs TLC (1.0367 g/ml for men and 1.0221 g/ml for women) (p less than 0.05). Percent fat values for the RV and TLD data differed by only 0.5% for men and 0.9% for women. Results indicated that the difference between percent fat determination by HW at RV and TLC, was negligible. It was concluded that HW at TLC may be the method of choice for subjects who are uncomfortable with performing the technique of underwater weighing at RV.

Adipose Tissue↗