No abstract

Acceleration, or an increase in the rate of movement, is integral to success in many sports. Improvements in acceleration often entail workouts done at intensities that elicit higher blood lactate concentrations (BLa). The purpose of the study is to assess the impact of acceleration on BLa. Methods required subjects (n = 45) to perform 4 workouts that each involved two 1-minute sets of hip- and knee-extension repetitions on an inertial exercise trainer (Impulse Training Systems, Newnan, Georgia). Subjects performed 2 workouts comprised solely of phasic or tonic repetitions; their sequence was randomized to prevent an order effect. Before and 5 minutes after exercise, subjects' BLa were assessed with a calibrated analyzer (Sports Resource Group, Hawthorne, New York). Post and delta (post-pre) BLa both served as criterion measures for multivariate analysis. Average and peak acceleration values, derived from both phasic and tonic workouts, served as predictor variables. Results showed statistical significance (p < 0.05; R = 0.2534) and yielded the following prediction equation from phasic workouts: delta BLa = 1.40 + 1.116 (average acceleration set 1)--0.011 (peak acceleration set 1)--0.634 (average acceleration set 2) + 0.005 (peak acceleration set 2). Conclusions suggest delta BLa variance, which represents the increase of the metabolite incurred from workouts, is most easily explained by average acceleration values, which describes the mean increase in the rate of movement from phasic workouts. To improve an athlete's tolerance for acceleration-induced BLa increases, workouts should be tailored with respect to the muscles involved and the duration of exercise bouts of their chosen sport.

Our study purpose examined salivary hormonal responses to high-speed resistive exercise. Healthy subjects (n = 45) performed 2 elbow flexor workouts on a novel (inertial kinetic exercise; Oconomowoc, WI, USA) strength training device. Our methods included saliva sample collection at both preexercise and immediately postexercise; workouts entailed two 60-second sets separated by a 90-second rest period. The samples were analyzed in duplicate for their testosterone and cortisol concentrations ([T], [C]). Average and maximum elbow flexor torque were measured from each exercise bout; they were later analyzed with a 2(gender) × 2(workout) analysis of variance (ANOVA) with repeated measures for workout. The [T] and [C] each underwent a 2(gender) × 2(time) ANOVA with repeated measures for time. A within-subject design was used to limit error variance. Average and maximum torque each had gender (men > women; p < 0.05) effects. The [T] elicited a 2-way interaction (p < 0.05), as men incurred a significant 14% increase over time, but women's values were unchanged. Yet multivariate regression revealed that 3 predictor variables (body mass and average and maximum torques) did not account for a significant amount of variance associated with the rise in male [T]. Changes in [C] were not significant. In conclusion, changes in [T] concur with the results from other studies that showed significant elevations in male [T], despite the brevity of current workouts and the rather modest volume of muscle mass engaged. Practical applications imply that salivary assays may be a viable alternative to blood draws from athletes, yet coaches and others who may administer this treatment should know that our results may have produced greater pre-post hormonal changes if postexercise sample collection had occurred at a later time point.

A high-speed, low-resistance inertial exercise trainer (IET, Impulse Training Systems, Newnan, Ga) is increasingly employed in rehabilitative and athletic performance settings. Repetitions on an IET are done through a large range of motion because multijoint movements occur over more than one plane of motion, with no limitation on velocities or accelerations attained. The current study purpose is to assess data reproducibility from an instrumented IET through multiple test-retest measures. Data collection methods required the IET left and right halves to be fitted with a TLL-2K force transducer (Transducer Techniques, Temecula, Calif) on one of its pulleys, and an infrared position sensor (Model CX3-AP-1A, automationdirect.com) located midway on the underside of each track. Signals passed through DI-158U signal conditioners (DATAQ Instruments, Akron, Ohio) and were measured with a four-channel analog data acquisition card at 4000 Hz. To assess data reproducibility, college-age subjects (n = 45) performed four IET workouts that were spaced 1 week apart. Workouts entailed two 60-second sets of repetitive knee- and hip-extensor muscle actions as subjects were instructed to exert maximal voluntary effort. Results from multiple test-retest measures show that the IET elicited reproducible intra- and interworkout data despite the unique challenge of multiplanar and multijoint exercise done over a large range of motion. We conclude that future studies in which IET performance measurement is required may choose to instrument the device with current methodology. Current practical applications include making IET data easier to comprehend for the coaches, athletes, and health care providers who use the device.

The purpose of the study was to compare blood lactate and hormonal responses with flywheel ergometer (FERG) leg presses for preliminary assessment of workouts best suited for future in-flight resistance exercise. Comprised of 10 repetition sets, the workouts entailed 3 sets of concentric and eccentric (CE3) actions, or concentric-only actions done for 3 (CO3) or 6 (CO6) sets. Methods employed included assessment of blood lactate concentrations ([BLa-]) before and 5 minutes postexercise. Venous blood was also collected before and at 1 and 30 minutes postexercise to assess growth hormone, testosterone, cortisol concentrations ([GH], [T], [C]) and [T/C] ratios. [BLa-] were compared with 2 (time) x 3 (workout) analysis of variance. Hormones were assessed with 2 (gender) x 3 (time) x 3 (workout) analysis of covariances. Results showed [BLa-] had a time effect. Growth hormone concentration showed gender x workout, gender x time, and workout x time interactions, whereas [T] had a 3-way interaction. [C] had gender, time, and workout effects. [T/C] yielded a gender x time interaction. It was concluded that, because CO6 and CE3 yielded similar anabolic hormonal data but the latter had a lower [C] 30 minutes postexercise, CE3 served as the best workout. Although the FERG was originally designed for microgravity, the effort put forth by current subjects was like that for workouts aimed at greater athletic performance and conditioning. Practical applications suggest that eccentric actions should be used for FERG workouts geared toward muscle mass and strength improvement.