Lincoln A. Gotshalk

Low-volume circuit versus high-volume periodized resistance training in women.

PURPOSE The purpose of this investigation was to determine the long-term training adaptations associated with low-volume circuit-type versus periodized high-volume resistance training programs in women. METHODS 34 healthy, untrained women were randomly placed into one of the following groups: low-volume, single-set circuit (SSC; N = 12); periodized high-volume multiple-set (MS; N = 12); or nonexercising control (CON) group (N = 10). The SSC group performed one set of 8-12 repetitions to muscular failure 3 d x wk(-1). The MS group performed two to four sets of 3-15 repetitions with periodized volume and intensity 4 d x wk(-1). Muscular strength, power, speed, endurance, anthropometry, and resting hormonal concentrations were determined pretraining (T1), after 12 wk (T2), and after 24 wk of training (T3). RESULTS 1-RM bench press and leg press, and upper and lower body local muscular endurance increased significantly (P < or = 0.05) at T2 for both groups, but only MS showed a significant increase at T3. Muscular power and speed increased significantly at T2 and T3 only for MS. Increases in testosterone were observed for both groups at T2 but only MS showed a significant increase at T3. Cortisol decreased from T1 to T2 and from T2 to T3 in MS. Insulin-like growth factor-1 increased significantly at T3 for SSC and at T2 and T3 for MS. No changes were observed for growth hormone in any of the training groups. CONCLUSION Significant improvements in muscular performance may be attained with either a low-volume single-set program or a high-volume, periodized multiple-set program during the first 12 wk of training in untrained women. However, dramatically different training adaptations are associated with specific domains of training program design which contrast in speed of movement, exercise choices and use of variation (periodization) in the intensity and volume of exercise.

Effect of resistance training on women's strength/power and occupational performances.

PURPOSE The effects of resistance training programs on strength, power, and military occupational task performances in women were examined. METHODS Untrained women aged (mean +/- SD) 23 +/- 4 yr were matched and randomly placed in total- (TP, N = 17 and TH, N = 18) or upper-body resistance training (UP, N = 18 and UH, N = 15), field (FLD, N = 14), or aerobic training groups (AER, N = 11). Two periodized resistance training programs (with supplemental aerobic training) emphasized explosive exercise movements using 3- to 8-RM training loads (TP, UP), whereas the other two emphasized slower exercise movements using 8- to 12-RM loads (TH, UH). The FLD group performed plyometric and partner exercises. Subjects were tested for body composition, strength, power, endurance, maximal and repetitive box lift, 2-mile loaded run, and U.S. Army Physical Fitness Tests before (T0) and after 3 (T3) and 6 months of training (T6). For comparison, untrained men (N = 100) (MEN) were tested once. RESULTS Specific training programs resulted in significant increases in body mass (TP), 1-RM squat (TP, TH, FLD), bench press (all except AER), high pull (TP), squat jump (TP, TH, FLD), bench throw (all except AER), squat endurance (all except AER), 1-RM box lift (all except aerobic), repetitive box lift (all), push-ups (all except AER), sit-ups (all except AER), and 2-mile run (all). CONCLUSIONS Strength training improved physical performances of women over 6 months and adaptations in strength, power, and endurance were specific to the subtle differences (e.g., exercise choice and speeds of exercise movement) in the resistance training programs (strength/power vs strength/hypertrophy). Upper- and total-body resistance training resulted in similar improvements in occupational task performances, especially in tasks that involved upper-body musculature. Finally, gender differences in physical performance measures were reduced after resistance training in women, which underscores the importance of such training for physically demanding occupations.

Acute hormonal responses to heavy resistance exercise in younger and older men.

Abstract The purpose of this investigation was to examine the acute responses of several hormones [total and free testosterone (TT and FT, respectively), adrenocorticotropic hormone (ACTH), cortisol (C), growth hormone (GH), and insulin (INS)] to a single bout of heavy resistance exercise (HRE). Eight younger [30-year (30y) group] and nine older [62-year (62y) group] men matched for general physical characteristics and activity levels performed four sets of ten repetitions maximum (RM) squats with 90 s rest between sets. Blood samples were obtained from each subject via an indwelling cannula with a saline lock pre-exercise, immediately post-exercise (IP), and 5, 15 and 30 min post-exercise. Levels of TT, FT, ACTH, C and lactate significantly increased after HRE for both groups. Pre-HRE pairwise differences between groups were noted only for FT, while post-HRE pairwise differences were found for TT, FT, GH, glucose and lactate. Area under the curve analysis showed that the 30y group had a significantly higher magnitude of increase over the entire recovery period (IP, 5, 15, and 30 min post-exercise) for TT, FT, ACTH and GH. Few changes occurred in the INS response with the only change being that the 62y group demonstrated a decrease IP. Lactate remained elevated at 30 min post-HRE. This investigation demonstrates that age-related differences occur in the endocrine response to HRE, and the most striking changes appear evident in the FT response to HRE in physically active young and older men.

Creatine supplementation improves muscular performance in older men.

PURPOSE Creatine supplementation has been shown to enhance muscle strength and power after only 5-7 d in young adults. Creatine supplementation could therefore benefit older individuals because aging is associated with a decrease in muscle strength and explosive power. METHODS We examined the effects of 7 d of creatine supplementation in normally active older men (59-72 yr) by using a double-blind, placebo-controlled design with repeated measures. After a 3-wk familiarization period to minimize learning effects, a battery of tests was completed on three occasions separated by 7 d (T1, T2, and T3). After T1, subjects were matched and randomly assigned into creatine (N = 10) and placebo (N = 8) groups. After T2, subjects consumed supplements (0.3 g x kg(-1) x d(-1)) for 7 d until T3. All subjects were tested for maximal dynamic strength (one-repetition maximum leg press and bench press), maximal isometric strength (knee extension/flexion), upper- and lower-body explosive power (6 x 10-s sprints on a cycle ergometer), and lower-extremity functional ability (timed sit-stand test and tandem gait test). Body composition was assessed via hydrostatic weighing, and blood samples were obtained to assess renal and hepatic responses and muscle creatine concentrations. RESULTS No significant increases in any performance measures were observed from T1 to T2 with the exception of isometric right-knee flexion in the placebo group indicating stability in the testing protocols. Significant group-by -time interactions indicated the responses from T2 to T3 were significantly greater (P <or= 0.05) in the creatine compared with the placebo group, respectively, for body mass (1.86 and -1.01 kg), fat-free mass (2.22 and 0.00 kg), maximal dynamic strength (7-8 and 1-2%), maximal isometric strength (9-15 and -6 to 1%), lower-body mean power (11 and 0%), and lower-extremity functional capacity (6-9 and 1-2%). No adverse side effects were observed. CONCLUSION These data indicate that 7 d of creatine supplementation is effective at increasing several indices of muscle performance, including functional tests in older men without adverse side effects. Creatine supplementation may be a useful therapeutic strategy for older adults to attenuate loss in muscle strength and performance of functional living tasks.

The effect of heavy resistance exercise on the circadian rhythm of salivary testosterone in men.

Abstract Circadian rhythms of serum testosterone concentrations in men have been shown, in general, to be highest in the morning and lowest in the evening. Thus, the purpose of this investigation was to determine the effects of acute resistance exercise upon the waking circadian rhythm of salivary testosterone over 2 days (with or without resistance exercise). The subjects included ten resistance-trained men (with at least 1 year of lifting experience) with the following characteristics [mean (SD)]: age 21.6 (1.1) years; height 177.8 (9.5) cm; body mass 80.5 (11.5) kg; percent body fat 7.9 (1.7)%. A matched, randomized, crossover study design was used such that each subject was tested under both the resistance exercise and control (no exercise) conditions. The resistance exercise protocol consisted of ten exercises performed for three sets of ten repetitions maximum with 2 min of rest between sets. Saliva sample 1 was collected at 0615 hours and resistance exercise began immediately afterwards at approximately 0620 hours, and sample 2 was collected at 0700 hours, which corresponded approximately to a mid-exercise (or control) time point. Saliva samples were then obtained every hour on the hour from 0800 hours until 2200 hours. No significant differences were observed between the exercise and resting conditions for salivary testosterone, with the exception of a significant decrease at 0700 hours during the resistance exercise protocol. The results of this investigation indicate that resistance exercise does not affect the circadian pattern of salivary testosterone secretion over a 16-h waking period in resistance-trained men.

Cardiovascular Responses to a High-Volume Continuous Circuit Resistance Training Protocol

The purpose of this investigation was to determine the level of cardiovascular stress elicited by continuous and prolonged circuit resistance training (CRT). Each of the 11 men who volunteered as a subject were tested to determine oxygen consumption and heart rate responses to a submaximal and maximal treadmill protocol and a CRT session consisting of 10 exercises and 10 repetitions at 40% of 1 repetition maximum (1RM) for each station with 4.6 circuits performed. The physiological stress of the CRT in this study was evident by the sustained heart rate of more than 70% of maximum for 16.6 minutes, with the last 12 minutes at more than 80%. Despite the large anaerobic component in CRT, VO2 was sustained at 50% or more of maximum for the final 12 minutes. Treadmill running, involving large muscle groups, increased VO2 more rapidly than CRT, where alternating larger and smaller muscle groups were used. In addition, at the same VO2 heart rate differed significantly between the 2 modes of activity. Heart rate in CRT was higher (at 165) than the heart rate of 150 found during treadmill running at the same 50% VO2. Such workouts may be used in a training cycle in classical linear periodization or in a nonlinear program day targeting local muscular endurance under intense cardiorespiratory conditions, which may help individuals develop enhanced toleration of physiological environments where high cardiovascular demands and higher lactate concentrations are present.

Comparison of body composition assessment among lean black and white male collegiate athletes.

Variations in the density of the fat-free mass (DFFM) across ethnic groups is a critical factor that invalidates the use of body fat equations. It has also been suggested that resistance trained athletes may have higher body densities (BDs) than untrained subjects. Thus, the validity of using anthropometric (ANT) equations, which have mainly been derived on white nonathletic groups, has been questioned for athletic white and black men. This study compared BD and percent body fat (%BF) between 34 white (20 +/- 1 yr, 184 +/- 11 cm, 84 +/- 12 kg, 25 +/- 3 BMI) and 30 black (20 +/- 1 yr, 182 +/- 9 cm, 84 +/- 12 kg, 25 +/- 2 BMI) male collegiate athletes and determined the accuracy of 5 ANT equations in estimating %BF. Subjects were underwater weighed (UWW), and skinfold measurements were obtained from the chest, mid-axillary, abdomen, suprailiac, subscapula, triceps, and thigh. BD was obtained from UWW and estimated from the five skinfold equations. From UWW, significant (P < or = 0.05) differences were found for BD (1.075 +/- 0.007 vs 1.0817 +/- 0.009), but not for %BF (10.49 +/- 2.8 vs 11.59 +/- 3.4) for white and black subjects, respectively. Differences were noted for subcutaneous skinfold sites (abdominal (vertical), suprailiac, and thigh), sum of three and seven skinfolds, and proportion of subscapular subcutaneous fat. One out of five and five out of five ANT equations (Siri conversions) yielded significantly lower estimates compared with UWW %BF for the white and black athletes, respectively. Use of the Schutte equation for the black athletes resulted in overpredictions of %BF for five out of five equations. In addition, the Schutte equation offered slightly greater accuracy than did the Siri equation for estimating %BF in black athletes. These data confirm earlier concerns that ANT equations derived on general populations may not be as accurate for athletic populations and also suggest that correction equations are necessary for converting BD into %BF for populations differing with respect to race or training status.

Relation Between C-Reactive Protein Levels and Body Composition in a Multiethnic Sample of School Children in Hawaii

Adipose cells secrete proinflammatory cytokines that stimulate hepatic production of C‐reactive protein (CRP). CRP levels are associated with adiposity levels in adults, adolescents, and older children but not in young children (age 2–3). This study examined the relation between CRP, adiposity, and cardiovascular and metabolic variables including blood pressure, glucose, and blood lipids in two young cohorts of children, averaging ∼5.5 and 8.5 years, respectively.

Measures of adiposity in two cohorts of Hawaiian school children

Background: Native Hawaiians have high rates of obesity and obesity-related diseases compared with non-Hawaiians in Hawaii, and the relation between this ethnic disparity in adiposity and socioeconomic status (SES) in children is unclear. Aim: The present study compared measures of adiposity in two cohorts of school children residing in the Hilo area of Hawaii and related these measures to parental reports of ethnicity, household income and parent educational attainment. Subjects and methods: All children in either Kindergarten (mean age 5.6 years) or third grade (mean age 8.7 years) in eight elementary schools in the Hilo area were invited to participate. A total of 125 children had anthropometric, bioelectric impedance and air displacement plethysmography measurements taken and their parents answered questions about household income, parental educational attainment and genealogical background that included ethnicity of ancestors. Results: Boys and girls in both cohorts had stature approximately at the 50th percentile (Z-score = 0) of national samples (CDC data). Z-scores of BMI were elevated compared to the CDC reference curves, but were significantly higher in male Native Hawaiian children in the older cohort among whom nearly 50% had a BMI above the 95th percentile for age. In the younger cohort, there was no significant ethnic difference in adiposity measures. In the older cohort, Native Hawaiian boys had significantly higher adiposity measures than their classmates. Adiposity in third grade girls was significantly and inversely related to their fathers educational attainment. Percentage of Hawaiian ancestry was not significantly related to adiposity measures. Conclusions: Ethnic disparity in adiposity among Native Hawaiians compared with non-Hawaiian age mates occurs after the age of 6 years, and is confined to males in this sample. For older girls, fathers, but not mothers, educational attainment was inversely related to adiposity.

Physical activity level and body composition in a multiethnic sample of school children in Hawaii

Abstract Background: Obesity, particularly in Native Hawaiians, is an important health risk. A possible contributing factor to obesity is reduced physical activity levels. Aim: This study investigates the relationship between measured levels of physical activity and body composition in two grade cohorts of school children of Native Hawaiian/Pacific Islander (NHPI) and non-NHPI ethnicity. Methods: A sample of 105 Kindergarteners and third graders were measured for adiposity, physical fitness, and physical activity levels. Ethnicity was determined from genealogical surveys. BMI, waist circumference (WC) and body fat percentage derived from air displacement plethysmography were used to evaluate adiposity. Maximal oxygen consumption (VO2max/kg) was estimated and total energy expenditure (TEE), physical activity level (PAL) and percentage of time inactive (PTI) were determined using the Flex-heart rate method. Results: VO2max, but not TEE, PAL or PTI, was significantly correlated with BMI in Kindergarteners; while VO2max and PAL were negatively correlated with BMI, PAL was significantly negatively correlated with WC and PTI was positively correlated with fat percentage among third graders. There were no significant ethnic differences in VO2max, TEE, PAL or PTI. Conclusions: PAL and PTI are moderately related to adiposity measures, and there are no ethnic differences in physical activity or fitness measures in this sample.