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Although it is generally accepted that human performance must be assessed in a manner specific to the training, previous studies have violated this principle. In order to determine the validity of evaluating short-term resistance training programs with isometric and isokinetic measures, 23 recreationally active males participated in an 8-week training program. Subjects were randomly divided into barbell squat, hip sled, leg extension, and control groups. Pre- and posttesting of quadriceps strength was performed with a Cybex isokinetic dynamometer. Six angle-specific torques (N.m) were determined at 0 rad-s^-1 and 1.05 rad-s^-1. Ten RM training loads increased significantly for all groups that trained. Isometric torque values differed significantly from isokinetic torque values at 30, 60, 75, and 90° of leg flexion for all groups. No significant torque increases from pre- to posttest were observed for any group at any limb angle for either isometric or isokinetic testing, or for isokinetic peak torque. This indicates that strength increases during short-term dynamic external resistance exercise are not adequately assessed with either isometric or isokinetic evaluations.

Research in achievement goal perspective theory suggests that the creation of a caring/task-involving (C/TI) climate results in more advantageous psychological and behavioral responses relative to an ego-involving (EI) climate; however, research has not yet examined the physiological consequences associated with psychological stress in relation to climate. Given the possible health and fitness implications of certain physiological stress responses, it is critical to understand this association. Thus, the purpose of this study was to examine whether an EI climate procures increases in the stress-responsive hormone cortisol, as well as negative psychological changes, following the learning of a new skill, compared with a C/TI climate. Participants (n = 107) were randomized to a C/TI or an EI climate in which they learned how to juggle for 30 min over the course of 2 hr. Seven salivary cortisol samples were collected during this period. Results indicated that EI participants experienced greater cortisol responses after the juggling session and significantly greater anxiety, stress, shame, and self-consciousness relative to C/TI participants. In contrast, the C/TI participants reported greater enjoyment, effort, self-confidence, and interest and excitement regarding future juggling than the EI participants. These findings indicate that motivational climates may have a significant impact on both the physiological and psychological responses of participants.

To determine absolute and relative (adjusted for body mass) strength, mean power, and mean velocity for upper and lower body resistance exercises, forty-seven young boys and girls participated in maximal strength testing. Healthy young boys and girls, ages 3- to 7-years old, were tested for one-repetition maximum (1-RM) strength, and 70% of 1-RM to determine mean power and mean velocity on the chest press and leg press exercises. Adult weight machines were modified to accommodate the smaller size and lower strength levels of the children. A 2 × 4 (sex × age) ANOVA was used to determine age and sex differences in performance. No interaction or sex differences were observed for any variable at any age. 1-RM strength, mean power, and mean velocity significantly increased across ages (p ≤ .05). When adjusted for body mass, the changes were insignificant, with one exception. Relative mean power for the bench press increased with age. Data indicated children from 3-7 years of age are capable of performing strength and power tests, but may require more attempts at maximal loads compared with adults. It appears that muscular strength and velocity during this stage of development are primarily dependent on increasing body mass, whereas power is influenced by additional variable(s).

The purpose of this study was to evaluate the effect of glycine propionyl-Lcarnitine (GPLC) supplementation and endurance training for 8 wk on aerobicand anaerobic-exercise performance in healthy men and women (age 18–44 yr). Participants were randomly assigned to 1 of 3 groups: placebo (n = 9), 1 g/d GPLC (n = 11), or 3 g/d GPLC (n = 12), in a double-blind fashion. Muscle carnitine (vastus lateralis), VO_2peak, exercise time to fatigue, anaerobic threshold, anaerobic power, and total work were measured at baseline and after an 8-wk aerobic-training program. There were no statistical differences (p > .05) between or within the 3 groups for any performance-related variable or muscle carnitine concentrations after 8 wk of supplementation and training. These results suggest that up to 3 g/d GPLC for 8 wk in conjunction with aerobic-exercise training is ineffective for increasing muscle carnitine content and has no significant effects on aerobic- or anaerobic-exercise performance.

The use of resistance training for children has increased in popularity and interest. It appears that children are capable of voluntary strength gains. Exercise prescription in younger populations is critical and requires certain program variables to be altered from adult perspectives. Individualization is vital, as the rate of physiological maturation has an impact on the adaptations that occur. The major difference in programs for children is the use of lighter loads (i.e., > 6 RM loads). It appears that longer duration programs (i.e., 10-20 wks) are better for observing training adaptations. This may be due to the fact that it takes more exercise to stimulate adaptational mechanisms related to strength performance beyond that of normal growth rates. The risk of injury appears low during participation in a resistance training program, and this risk is minimized with proper supervision and instruction. Furthermore, with the incidence of injury in youth sports, participation in a resistance training program may provide a protective advantage in one’s preparation for sports participation.

Displacement-based measurement systems are becoming increasingly popular for assessment of force expression variables during resistance exercise. Typically a linear position transducer (LPT) is attached to the barbell to measure displacement and a double differentiation technique is used to determine acceleration. Force is calculated as the product of mass and acceleration. Despite the apparent utility of these devices, validity data are scarce. To determine whether LPT can accurately estimate vertical ground reaction forces, two men and four women with moderate to extensive resistance training experience performed concentric-only (CJS) and rebound (RJS) jump squats, two sessions of each type in random order. CJS or RJS were performed with 30%, 50%, and 70% one-repetition maximum parallel back squat 5 minutes following a warm-up and again after a 10-min rest. Displacement was measured via LPT and acceleration was calculated using the finite-difference technique. Force was estimated from the weight of the lifter-barbell system and propulsion force from the lifter-barbell system. Vertical ground reaction force was directly measured with a single-component force platform. Two-way random average-measure intraclass correlations (ICC) were used to assess the reliability of obtained measures and compare the measurements obtained via each method. High reliability (ICC > 0.70) was found for all CJS variables across the load-spectrum. RJS variables also had high ICC except for time parameters for early force production. All variables were significantly (p < 0.01) related between LPT and force platform methods with no indication of systematic bias. The LPT appears to be a valid method of assessing force under these experimental conditions.

The testosterone-to-cortisol ratio (T/C) has been shown to be positively correlated with strength and power. However, few studies have examined the relationship between a standardized power performance measurement and T/C throughout a season of intercollegiate competition. The purpose of this study was to examine the relationships between salivary T/C and vertical jump (VJ) performance of female National Collegiate Athletic Association Division II basketball players across a season. Saliva samples were taken before practice, weekly, for a total of 29 weeks. Samples were assayed for testosterone (T) and cortisol (C). After saliva collection, players completed two countermovement VJs, with the best jump used for data analysis. A positive correlation between T/C and VJ was seen only during the preseason phase. Statistically significant differences were observed across the season for T/C and VJ. T/C in the nonconference phase was significantly lower than the preseason phase and the late-conference phase, p = .013 and p = .047, respectively. VJ was significantly lower in the late-conference phase when compared to the preseason and nonconference phases, p < .001 and p = .026, respectively. VJ in the early-conference phase was also significantly lower than the preseason phase, p < .001. These data support the literature that has indicated a positive relationship between the T/C and lower-body power but only in the preseason phase. This relationship reverses and trends toward a negative relationship, before disappearing in the second half of the season. Monitoring T/C may provide value in assessing female athletes’ performance potential in the preseason phase. T/C should be interpreted with more caution once the competitive season begins.