No description available.

There is a need for reliable analysis techniques for kinetic data for coaches and sport scientists who employ athlete monitoring practices. The purpose of the study was: (1) to determine intra- and inter-rater reliability within a manual-based kinetic analysis program; and (2) to determine test-retest reliability of an algorithm-based kinetic analysis program. Five independent raters used a manual analysis program to analyse 100 isometric mid-thigh pull (IMTP) trials obtained from previously collected data. Each trial was analysed three times. The same IMTP trials were analysed using an algorithm-based analysis software. Variables measured were peak force, rate of force development from 0 to 50 ms (RFD50) and RFD from 0 to 200 ms (RFD200). Intraclass correlation coefficients (ICC) and coefficient of variation (CV) were used to assess intra- and inter-rater reliability. Nearly perfect reliability was observed for the manual-based (ICC > 0.92). However, poor intra- and inter-rater CV was observed for RFD (CV > 16.25% and CV > 32.27%, respectively). The algorithm-based method resulted in perfect reliability in all measurements (ICC = 1.0, CV = 0%). While manual methods of kinetic analysis may provide sufficient reliability, the perfect reliability observed within the algorithm-based method in the current study suggest it is a superior method for use in athlete monitoring programs.

Abstract available in the Journal of Strength and Conditioning Research.

Abstract available in the Journal of Strength and Conditioning Research.

No description available.

Purpose: Monitor changes in force production, running economy (RE), and running kinematics (RK) in a highly trained marathon runner after beginning a strength training (ST) program. Methods: One marathon runner (M, 27 y, 165 cm, 53.3 kg, VO2pesk 67.43 ml/kg/min, PR 2:33:13) with no history of ST completed a 12-week block periodized ST program. Baseline and reliability testing was conducted over a two-month period prior to ST. The completed ST RPE and work (volume load*displacement) and running volume (km/wk) were monitored over the 12 weeks. The athlete performed an isometric mid-thigh pull to assess peak force (PF, N), rate of force development at 250 ms (RFD250), and net impulse at 250 ms (NI250) during baseline and throughout ST. The athlete performed a steady state test on a treadmill instrumented with the OptojumpTM optic sensor system to assess RE (ml/kg/km) and RK during baseline and throughout ST. Impact of the ST program was assessed by percent change of the variables during the taper from the baseline average and by the odds of a true change using the typical error and smallest worthwhile change. Results: PF improved (120:1 odds) by 17.11%, RFD250 improved (22:1 odds) by 24.73%, and NI250 improved (10:1 odds) by 16.70% before competition. Ground contact time decreased (7:1 odds) by 2.57%, flight time decreased (1:1 odds) by 1.49%, step rate increased (2:1 odds) by 2.28%, and step length decreased (57:1: odds) by 2.21%. RE improved (3:1 odds) by 2.09%. Conclusion: Improving a runner’s maximal strength and rate of force development may positively influence RK and RE.

Aim: The purpose of this study was: 1) to investigate the alterations and relationships among training variables, performance variables, and physiological variables and 2) investigate the effects of strength training on potentiation complexes. Methods: The study enrolled nine D-1 collegiate throwers and four control subjects. The throwers participated in an 11-week resistance training and throws program. Resistance training volume load and throwing volume were recorded for 11 weeks. Measurements of maximal strength (isometric mid-thigh pulls) and dynamic mid-thigh pulls (DMTP) across a spectrum of loads: Males- 60kg, 140kg, 180kg, 220kg, 140kg, 30% isometric peak force (IPF), Females- 60kg, 80kg, 100kg, 120kg, 80kg, 30% IPF), were measured at weeks 1, 7, and 11. The control group was tested for isometric maximum strength at T1 (week 1) and T3 (week 11) Results: The throwers increased at each time point in isometric peak force (IPF), allometrically scaled IPF (IPFa), and isometric impulse. The throwers strength (IPF and IPFa) was significantly greater than the controls and the throwers experienced statistically significant changes in maximum strength from T1 to T3 when compared to the controls. The throwers demonstrated statistically significant changes in total load variables (variable for load 1+ load 2 + load 3 etc.) for DMTPs. Conclusion: As a whole these data suggest a potential for increased performance capabilities specific to throwing. Some data trends indicate that potentiation can occur as a result of performing a heavy pull before a lighter one. However, increasing maximum strength as a result of focusing on strength training did not enhance this potentiation effect.

Whole-body vibration (WBV) may positively influence performance acutely through the potentiation of the muscle’s series elastic components and neuromuscular mechanisms. The purpose of this investigation was to examine the acute effects of WBV on sprint performance in NCAA Division I collegiate male sprinters and jumpers. Twenty-one athletes (n=21) completed a control or WBV protocol (30 seconds, 50 Hz, low amplitude ~3mm) one minute before a 30 m flying sprint. Each athlete participated in three separate trials using randomized treatment sessions (1 treatment per session) over 12 weeks of preparation training prior to the indoor season. The control condition consisted of no vibration, while treatment 1 (T1) and treatment 1 repeated (T1-R) incorporated vibration. The vibration-sprint protocol was repeated after a five minute rest period following the first sprint (test-re-test ICC≥0.81). The sprint consisted of a 15 m run-in from a standing start and a 30 m flying sprint with a total distance of 45 m. A two-way factorial ANOVA with repeated measures (p ≤ 0.05) was used to compare treatments. Statistics showed no differences between the treatments at all distances (average sprint time of control vs. T1, control vs. T1-R, and T1 vs. T1-R). The results of this study indicate that WBV at 50 Hz and low amplitude has no potentiation effect on sprint times (15, 30, 45, or 30 m fly). Further research is needed to determine if different WBV protocols may elicit enhanced results in 30 m flying sprint performance. The present WBV protocol does not appear to have practical acute value for sprinting.

The purposes of this study were to examine the effect of ballistic concentric-only half-squats (COHS) on subsequent squat-jump (SJ) performances at various rest intervals and to examine the relationships between changes in SJ performance and bilateral symmetry at peak performance. Thirteen resistance-trained men performed an SJ immediately and every minute up to 10 min on dual force plates after 2 ballistic COHS repetitions at 90% of their 1-repetition-maximum COHS. SJ peak force, peak power, net impulse, and rate of force development (RFD) were compared using a series of 1-way repeated-measures ANOVAs. The percent change in performance at which peak performance occurred for each variable was correlated with the symmetry index scores at the corresponding time point using Pearson correlation coefficients. Statistical differences in peak power (P = .031) existed between rest intervals; however, no statistically significant pairwise comparisons were present (P > .05). No statistical differences in peak force (P = .201), net impulse (P = .064), and RFD (P = .477) were present between rest intervals. The relationships between changes in SJ performance and bilateral symmetry after the rest interval that produced the greatest performance for peak force (r = .300, P = .319), peak power (r = –.041, P = .894), net impulse (r = –.028, P = .927), and RFD (r = –.434, P = .138) were not statistically significant. Ballistic COHS may enhance SJ performance; however, the changes in performance were not related to bilateral symmetry.

Objectives: The purpose of this study was to examine the relationship of velocities in the back squat between one repetition maximum (1RM) and submaximally loaded repetition maximum (RM) conditions, specifically in regard to what has been described as the minimal velocity threshold (MVT). The MVT describes a minimum concentric velocity that an individual must reach or surpass in order to successfully complete a repetition. Design: To test the presence of a MVT, participants were tested for 1RM and RM back squat ability. The mean concentric veloci ties (MCV) of the last successful repetition of each condition were then compared. Methods: Fourteen male participants familiar with the back squat volunteered to participate in the current study (age = 25.0 y ± 2.6, height = 178.9 cm ± 8.1, body mass = 88.2 kg ± 15.8). The mean concentric velocity (MCV) during the last successful repetition from each testing condition was considered for the comparison. Results: Results indicated a non-significant negative relationship of MCV between the 1RM and RM conditions (r = -0.135), no statistical difference between testing conditions (p = 0.266), with a small-to-moderate effect size (d = 0.468). Conclusions: The results of this study suggest that MVT should be further investigated to enhance its use in the practical setting. Additionally, coaches considering using a velocity-based approach for testing athletes should use data from either 1RM or RM conditions, but not both interchangeably. Coaches should be cautious when considering group averages or comparing velocity data between athletes, which may not be appropriate based on our results.