Several devices are available to measure vertical jump (VJ) height based on flight time, VJ reach height, or ground reaction forces. The purpose of this study was to determine the accuracy of a VJ mat for measuring flight time and VJ height compared with a VJ tester or a force plate. Seventeen men and 18 women (X ± SD; age = 20.9 ± 0.7 years, height = 176.1 ± 0.9 cm, weight = 72.6 ± 13.5 kg) served as subjects. Subjects performed counter-movement vertical jumps while standing on both a force plate (1,000 Hz) and a VJ mat. A Vertec VJ tester was used to measure jump reach. Compared with the force plate, the VJ mat reported greater VJ height (VJ mat = 0.50 ± 0.12 m, force plate = 0.34 ± 0.10 m) and flight time (VJ mat = 0.629 ± 0.078 seconds, force plate = 0.524 ± 0.077 seconds). Comparison of VJ heights from the VJ mat and the Vertec revealed no significant differences (Vertec = 0.48 ± 0.11 m). Regression analyses indicated strong relationships between testing methods and suggested that high VJ performances may be underestimated with the VJ mat. This particular VJ mat compared favorably with the Vertec but not the force plate. It seems that the different flight times derived from the VJ mat may permit the VJ mat to be in closer agreement with VJ heights from the Vertec. Also, the VJ mat may not be an appropriate tool for assessing high VJ performances (i.e., ≥0.70 m; ≈28 inches). Practitioners and researchers using similar VJ mats may not obtain accurate flight times and may underestimate high performers.

No abstract

Leucine ingestion reportedly activates the mTOR pathway in skeletal muscle, contributing to a hypertrophy response. The purpose of the study was to compare the post-resistance exercise effects of leucine and whey protein supplementation on endocrine responses and muscle mTOR pathway phosphorylation. On visit 1, subjects (X±SD; n=20; age=27.8±2.8yrs) provided baseline blood samples for analysis of cortisol, glucose and insulin; a muscle biopsy of the vastus lateralis muscle to assess mTOR signaling pathway phosphorylation; and were tested for maximum strength on the leg press and leg extension exercises. For visits 2 and 3, subjects were randomized in a double-blind crossover design to ingest either leucine and whey protein (10g+10g; supplement) or a non-caloric placebo. During these visits, 5 sets of 10 repetitions were performed on both exercises, immediately followed by ingestion of the supplement or placebo. Blood was sampled 30 min post-, and a muscle biopsy 45 min post-exercise. Western blots quantified total and phosphorylated proteins. Insulin increased (α<.05) with supplementation with no change in glucose compared to placebo. Relative phosphorylation of AKT and rpS6 were greater with leucine and whey supplementation compared to placebo. Supplementation of leucine and whey protein immediately after heavy resistance exercise increases anabolic signaling in human skeletal muscle.

Hahn, CJ, Jagim, AR, Camic, CL, and Andre, MJ. Acute effects of a caffeine-containing supplement on anaerobic power and subjective measurements of fatigue in recreationally active men. J Strength Cond Res 32(4): 1029-1035, 2018-Studies show mixed results for the effects of caffeine on performance, warranting further investigation. The purpose of this study was to examine the acute effects of a caffeine-containing supplement on anaerobic power and subjective measurements of fatigue during resisted sprinting on men. Fourteen recreationally active men (N = 14; [mean ± SD], age: 21.0 ± 0.7 years, height: 178.5 ± 5.1 cm, body mass: 77.3 ± 9.6 kg, and percent body fat: 12.6 ± 4.8%) participated in a double-blind, placebo-controlled, within-subject crossover design study. The first visit required each participant to complete 3 sets of practice sprints on a nonmotorized treadmill ranging from 10 to 20 seconds. During the second visit, participants completed 5 more practice sprints ranging from 15 to 25 seconds. During the third and fourth visits, participants ingested one serving of a caffeine-containing or placebo beverage (the opposite beverage was consumed during the fourth visit), rested for 20 minutes, and completed a dynamic warm-up before sprinting. Anaerobic power was assessed using a countermovement vertical jump and nonmotorized treadmill sprint test. Psychological variables were scored using a 5-point Likert scale. No significant (p ≤ 0.05) differences were observed between conditions for average (p = 0.22) or peak power (p = 0.43). Both conditions resulted in a significant increase in fatigue, although the increase was less for the caffeine condition (caffeine [INCREMENT] = 0.93 and placebo [INCREMENT] = 1.71). These findings indicated that the caffeine-containing supplement improved perceived measures of fatigue but not power indices assessed through vertical jump or nonmotorized treadmill sprinting. The consumption of a caffeine beverage may be beneficial for reducing perceived fatigue during acute anaerobic exercise, particularly when repeated sprints are used.

Heavy resistance exercise is often prescribed for collegiate basketball players to enhance game performance, but few data are available concerning the transference of lower body strength and power to the opportunity to play professionally after college. This study investigated if lower body muscular power and strength measures obtained during the barbell squat are related to future professional playing opportunities. The data was collected over a seven year period from a collegiate men’s basketball program (n=37; X±SD, age=20.0±1.4 yrs, hgt=1.98±0.09 m, bw=94.5±11.8 kg). Lower body strength was determined from 1 repetition maximum (1RM) tests of the parallel high-bar squat. Maximum lower body squat power was determined from speed squat testing across a load spectrum (30-90% 1RM) while an external tethered dynamometer or a 3-D video motion capture system quantified barbell power. Repeated measures ANOVA with Tukey’s HSD post hoc, Spearman ρ correlations, and Cohen’s D effect sizes were used to analyze the results. Subjects who subsequently played in the NBA or in professional leagues elsewhere had greater lower body strength and power. This was mainly attributed to their greater body mass, since strength and power relative to body mass was not different between the groups. Even without statistically significant differences, effect sizes consistently indicated moderate to large differences between the NBA and other professional groups when compared to those who did not play professionally. Regardless, lower body strength and power were related to post-collegiate playing opportunities, with greater values related to higher levels of professional play.