Despite consuming similar calories and protein during resistance training, daily supplementation with whey was more effective than soy protein or isocaloric carbohydrate control treatment conditions in promoting gains in lean body mass. These results highlight the importance of protein quality as an important determinant of lean body mass responses to resistance training.

The primary purpose of this investigation was to evaluate the influence of a whole body compression garment on recovery from a typical heavy resistance training workout in resistance-trained men and women. Eleven men (mean +/- SD: age, 23.0 +/- 2.9 years) and 9 women (mean +/- SD: age 23.1 +/- 2.2 years) who were highly resistance trained gave informed consent to participate in the study. A within-group (each subject acted as their own control), balanced, and randomized treatment design was used. Nutritional intakes, activity, and behavioral patterns (e.g., no pain medications, ice, or long showers over the 24 hours) were replicated 2 days before each test separated by 72 hours. An 8-exercise whole body heavy resistance exercise protocol using barbells (3 sets of 8-10 repetition maximum, 2.0- to 2.5-minute rest) was performed after which the subject showered and put on a specific whole body compression garment one designed for women and one for men (CG) or just wore his/her normal noncompression clothing (CON). Subjects were then tested after 24 hours. Dependent measures included sleep quality, vitality rating, resting fatigue rating, muscle soreness, muscle swelling via ultrasound, reaction movement times, bench throw power, countermovement vertical jump power, and serum concentrations of creatine kinase (CK) measured from a blood sample obtained via venipuncture of an arm vein. We observed significant (p < or = 0.05) differences between CG and CON conditions in both men and women for vitality (CG > CON), resting fatigue ratings (CG < CON), muscle soreness (CG < CON), ultrasound measure swelling (CG < CON), bench press throw (CG > CON), and CK (CG < CON). A whole body compression garment worn during the 24-hour recovery period after an intense heavy resistance training workout enhances various psychological, physiological, and a few performance markers of recovery compared with noncompressive control garment conditions. The use of compression appears to help in the recovery process after an intense heavy resistance training workout in men and women.

These observed inhomogeneous changes in CSA may alter the thigh's moment of inertia and moment arms of muscle "compartments," and the influence of elastic component force transmission on the muscular force expression. Such selective hypertrophy is speculated to be biomechanically beneficial to high-force or high-power movements used in training.

The purpose of this study was to examine the relationship between lower-body muscle structure and vertical jump performance. Twenty-five resistance-trained men (age, 23.3 +/- 3.2 years; height, 176.1 +/- 7.4 cm; and weight, 86.2 +/- 11.6 kg) took part in both anatomical and jump performance testing. Muscle fascicle thickness, fascicle length, and pennation angle were analyzed for the vastus lateralis (VL) and the lateral gastrocnemius (LG). Jump height and both relative and absolute power were measured for the squat jump (SJ), countermovement jump (CMJ), and depth drop jump (DDJ). Regressions were used to determine if jump performance could be predicted using the aforementioned structures. No VL measurements were significantly correlated with any of the jump measures. Lateral gastrocnemius pennation angle was a significant but weak predictor of jump height for all 3 jump types (SJ: r2 = 0.212, p = 0.021; CMJ: r2 = 0.186, p = 0.018; DDJ: r2 = 0.263, p = 0.005). When comparing jump height at increasing preloads, none of the variables of interest could significantly predict the jump height differences between CMJ and SJ. However, LG fascicle length had a weak but significant inverse relationship with DDJ-CMJ (r2 = 0.152; p = 0.031). Lateral gastrocnemius thickness was the strongest predictor of absolute power for all jump types and between jump types (SJ: r2 = 0.181, p = 0.034; CMJ: r2 = 0.201, p = 0.014; DDJ: r2 = 0.122, p = 0.049; CMJ-SJ: r2 = 0.201, p = 0.014; DDJ-CMJ: r2 = 0.146, p = 0.034). Lateral gastrocnemius pennation angle was also the best predictor of relative power for all 3 jump types and between jump types (SJ: r2 = 0.172, p = 0.038; CMJ: r2 = 0.416, p = 0.000; DDJ: r2 = 0.167, p = 0.024; CMJ-SJ: r2 = 0.391, p = 0.000; DDJ-CMJ: r2 = 0.136, p = 0.039). Results for jump performance differ from those previously found for sprinting in that greater pennation and shorter fascicles, positively predicting jumping ability at increased prestretch loads reinforcing the need for training specificity. Our findings in resistance-trained men indicate that where jumping is vital to athletic success one can benefit from developing LG muscle architecture along with addressing eccentric strength.

The purpose of this study was to verify the concurrent validity of a bar-mounted Myotest® instrument in measuring the force and power production in the squat and bench press exercises when compared to the gold standard of a computerized linear transducer and force platform system. Fifty-four men (bench press: 39-171 kg; squat: 75-221 kg) and 43 women (bench press: 18-80 kg; squat: 30-115 kg) (age range 18-30 years) performed a 1 repetition maximum (1RM) strength test in bench press and squat exercises. Power testing consisted of the jump squat and the bench throw at 30% of each subject's 1RM. During each measurement, both the Myotest® instrument and the Celesco linear transducer of the directly interfaced BMS system (Ballistic Measurement System [BMS] Innervations Inc, Fitness Technology force plate, Skye, South Australia, Australia) were mounted to the weight bar. A strong, positive correlation (r) between the Myotest and BMS systems and a high correlation of determination (R2) was demonstrated for bench throw force (r = 0.95, p < 0.05) (R2 = 0.92); bench throw power (r = 0.96, p < 0.05) (R2 = 0.93); squat jump force (r = 0.98, p < 0.05) (R2 = 0.97); and squat jump power (r = 0.91, p < 0.05) (R2 = 0.82). In conclusion, when fixed on the bar in the vertical axis, the Myotest is a valid field instrument for measuring force and power in commonly used exercise movements.

Despite the health benefits associated with physical activity (PA), screen time reduction, and sleep quantity and quality, the relationships between PA, screen time, and sleep quantity and quality remain unclear in adolescents. The present study is a cross-sectional analysis of data from adolescents aged 16–19 years who participated in the 2005–2006 National Health and Nutrition Examination Survey (n = 542). Multivariable logistic regression models, adjusted for confounders, examined the relationship between objectively measured PA, self-reported screen time, and sleep quantity and quality. Respondents who met the current PA recommendation had 50% lower odds of having sufficient sleep (≥8 h) than those not meeting the recommendation (OR = 0.50, 95% CI: 0.26, 0.94). Respondents who met the screen time recommendation (≤2 h/day) had 55% lower odds of reporting poor sleep quality than those whose screen time exceeded the recommendation (OR = 0.45, 95% CI: 0.22, 0.91), with similar patterns observed for females and males. However, males who met both PA and screen time recommendations had 73% lower odds of reporting poor sleep quality than males who met neither recommendation (OR = 0.27, 95% CI: 0.07, 0.99). In conclusion, PA and screen time are associated with sleep quantity or sleep quality in adolescents, and there are differences in these associations by sex.

Previous research has highlighted the importance of muscle and tendon structure to stretch shortening cycle performance. However, the relationships between muscle and tendon structure to performance are highly dependent on the speed and intensity of the movement. The purpose of this study was to determine if muscle and tendon structure is associated with the rate of force development (RFD) throughout static squat jump (SJ), countermovement jump (CMJ), and drop jump (DJ; 30-cm height). Twenty-five strength- and power-trained men participated in the study. Using ultrasonography, vastus lateralis (VL) and gastrocnemius (GAS) pennation (PEN) and fascicle length (FL), and Achilles tendon (AT) thickness and length were measured. Subjects then performed SJ, CMJ, and DJ, during which RFD was calculated over time 5 distinct time intervals. During CMJs, early RFD could be predicted between 0 and 10 milliseconds by both GAS-FL (r² = 0.213, β = 0.461) and AT-length (r² = 0.191, β = 20.438). Between 10 and 30 milliseconds GAS-FL was a significant predictor of CMJ-RFD (r² = 0.218, β = 0.476). During DJ, initial RFD (0-10 milliseconds) could be significantly predicted by GAS-FL (r² = 0.185, β = 20.434), VL-PEN (r² = 0.189, β = 0.435), and GAS-PEN (r² = 0.188, β = 0.434). These findings suggest that longer ATs may have increased elasticity, which can decrease initial RFD during CMJ; thus, their use in talent identification is not recommended. The GAS fascicle length had an intensity-dependent relationship with RFD, serving to positively predict RFD during early CMJs and an inverse predictor during early DJs. During DDJs, subjects with greater PEN were better able to redirected initial impact forces. Although both strength and plyometric training have been shown to increase FL, only heavy strength training has been shown to increase PEN. Thus, when a high eccentric load or multiple jumps are required, heavy strength training might be used to elicit muscular adaptations that are suited to fast force production during jumping.

Rehabilitation programs and research experiments use single-arm protocols in which the contralateral arm is not functional or used as a control limb. This study was interested in determining the hormonal signal impacts of such one- versus two-arm exercise responses that might have an impact on adaptational changes with training. The purpose was to examine the acute hormonal responses to a unilateral and a bilateral upper-body resistance exercise (RE) protocol. A balanced randomized treatment intervention with series time frame for blood collections before and after exercise was used as the basic experimental design. Ten recreationally resistance trained men (18-25 years, 20.4 +/- 1.2 years, 175.6 +/- 4.5 cm, 81.7 +/- 9.3 kg) gave informed consent to participate in the investigation. Each subject performed unilateral (dominant arm only) and bilateral upper-body RE protocol separated by 1 week in a balanced randomized fashion. The RE protocol consisted of 3 sets of 10 repetitions of 5 different dumbbell upper-body exercises at 80% of 1-repetition maximum, and blood samples were obtained before and 5, 15, and 30 minutes immediately postexercise (IP). Blood was obtained and analyzed for lactate, immunoreactive growth hormone (iGH), cortisol (C), total testosterone (T), and insulin concentrations. Total volume of work also was determined for the 2 exercise sessions. Total volume of work performed during the unilateral protocol was 52.1% of that for the bilateral protocol. Both RE protocols elicited a significant (p < or = 0.05) increase in lactate and iGH, but the increase for the bilateral condition was significantly greater. Cortisol decreased significantly during recovery for the unilateral condition. Testosterone was not affected by either protocol. Insulin was significantly increased at IP and 5 minutes postexercise for both conditions.These results indicate that the hormonal responses to dominant-arm unilateral RE is blunted compared to that for bilateral RE. This differential endocrine response is likely a result of the difference in volume between the protocols. It is important to pay attention to the amount of muscle mass utilized in a resistance exercise protocol to optimize endocrine signaling.