Lawrence Weiss - Academia.edu (original) (raw)
Papers by Lawrence Weiss
Journal of Strength and Conditioning Research, 2015
Harry, JR, Paquette, MR, Caia, J, Townsend, RJ, Weiss, LW, and Schilling, BK. Effects of footwear... more Harry, JR, Paquette, MR, Caia, J, Townsend, RJ, Weiss, LW, and Schilling, BK. Effects of footwear condition on maximal jumping performance. J Strength Cond Res 29(6): 1657-1665, 2015-The purpose of this investigation was to examine the effects of footwear on kinetics and lower extremity electromyographic (EMG) activity during the vertical jump (VJ) and standing long jump. Fifteen men performed the 2 jump types in 3 footwear conditions: barefoot, minimal shoes, and crosstraining shoes. Jump displacement and kinetic data were collected, along with EMG activity of the biceps femoris, medial gastrocnemius, peroneus longus, semitendinosus/semimembranosus, soleus (SOL), tibialis anterior, vastus lateralis, and vastus medialis. Subjective footwear performance and comfort were also assessed with a custom survey. No differences were found in jump displacement, peak ground reaction forces (GRF), countermovement and propulsive phase durations, vertical impulse, peak countermovement, or average propulsive EMG activity. Significant differences in peak propulsive root mean square EMG were found between barefoot and minimal shoes (p = 0.030) and minimal shoes and shod (p = 0.031) conditions for the SOL during the VJ, and for average countermovement EMG of the semitendinosus/semimembranosus during the VJ between barefoot and shod (p = 0.039). Moderate-to-large effect sizes (.0.59) were found between conditions for horizontal GRF, propulsive phase duration, average EMG amplitude, and duration of EMG activity during the countermovement. Participants reported higher comfort ratings when shod compared with barefoot and minimal shoes for both jumps. Participants also perceived better performance when shod compared with barefoot and minimal shoes for the VJ only. No acute differences in displacement were observed between barefoot, minimal shoes, and cross-trainer shoes during vertical and horizontal jumps. Some differences in muscle activation and timing seem to be present, and thus, training effects between footwear conditions should be examined. Footwear familiarization may prove beneficial, as acute increases in comfort seem unrelated to performance improvements. *SLJ = standing long jump; VJ = vertical jump; GRFz = vertical ground reaction force; GRFy = horizontal ground reaction force; ES = effect size. †Mean 6 SD for kinetic data: peak vertical ground reaction force (Peak GRFz) and peak horizontal ground reaction force (Peak GRFy 3 bodyweight), countermovement and propulsive phase duration (seconds), countermovement and propulsive impulse (N$s) for the barefoot, minimal shoes, and cross-training shoes (shod) are presented for the SLJ and VJ tests. Moderate-to-large ESs were found during the VJ for peak GRFy (barefoot vs. shod), propulsive phase duration (barefoot vs. shod; minimal shoes vs. shod), and countermovement impulse (barefoot vs. shod; minimal shoes vs. shod).
Journal of Strength and Conditioning Research, Sep 1, 2016
Body dimensions may influence various types of physical performance. This study was designed to e... more Body dimensions may influence various types of physical performance. This study was designed to establish the reliability and precision of bilateral lower-body dimensions using surface anatomic landmarks and either sliding calipers or goniometry. Fifty university students (25 men and 25 women) were measured on two separate occasions separated by 48 or 72 hours. A small digital caliper was used to acquire longitudinal dimensions of the feet, while a larger broad-blade caliper was used to measure lower-limb, hip, and pelvic dimensions. Quadriceps angle (Q-angle) was determined via surface goniometry. Data for all foot and lower-limb dimensions were both reliable and precise (intraclass correlation coefficient ≥ 0.72, standard error of measurement 0.1-0.5 cm). Measures of Q-angle were also reliable and precise (intraclass correlation coefficient ≥ 0.85, standard error of measurement 0.2-0.4 degrees). Findings from this investigation demonstrate that lower-body dimensions may be reliably and precisely measured via simple practical tests, when surface anatomic landmarks and standardized procedures are used. Although inter-tester reliability remains to be established, meticulous adherence to specific measurement protocols is likely to yield viable output for lower-body dimensions when more sophisticated methods are unavailable or inappropriate.
Isokinetics and Exercise Science, Oct 1, 1998
Isokinetics and Exercise Science, Oct 1, 1997
Two force and two power variables were monitored during standardized multiple-joint, closed-chain... more Two force and two power variables were monitored during standardized multiple-joint, closed-chain, velocity-spectrum tests to ascertain if contiguous velocities produced discrete or redundant output. Measurements were obtained from 52 men and 50 women during squats performed at six velocities ranging from 0.51 to 2.04 m· S-l. Main effects as well as the sex-by-main-effects interaction were significant (P < 0.001) for all four variables. Therefore, post hoc tests were performed separately for men and women. Maximal squatting forces over the velocity spectrum produced force-velocity curves resembling classical single-joint ones. The highest force output occurred at the slowest test velocity as expected and signifcantly decreased (P < 0.05) for each increment in velocity for both men and women. Concurrently, maximal squatting power over the velocity spectrum produced power-velocity curves resembling classical single-joint ones. The highest power output (x = 1.26 m . S-l) occurred as part of a plateau at intermediate velocities as expected and was signifcantly less at faster and slower velocities. However, maximal power output generally materialized at faster velocities for men (x = 1.54 m·s- 1 ) than for women (x = 0.97 m·s- 1 ). It appears the six squatting velocities used in this investigation elicit discrete force data for both men and women, and results for force and power resemble what would be expected for isolated single-joint testing protocols. However, it remains unclear why an apparent gender difference exists in the velocity at which the highest peak power is produced.
PubMed, Mar 1, 2001
Background: Various repetition strategies are employed in typical weight-training programs. Stren... more Background: Various repetition strategies are employed in typical weight-training programs. Strength is purportedly best developed using relatively few repetitions against great resistance. Strength in this context has typically been measured isotonically (dynamic constant external resistance or DCER) by performing a one-repetition maximum (1 RM). Multiple-joint isokinetic (velocity controlled) strength assessments are now available which may enable us to emulate movement patterns and velocities with those occurring in everyday activities while providing us with force and power information that heretofore has been difficult to obtain. Therefore, we assessed the effects of various repetition schemes during heavy-resistance training on multiple-joint isokinetic performance. METHODS. Setting: Volunteers participated in 12 weeks (36 sessions) of variable-resistance weight training (8 different exercises) in one of the following programs: I-3 sets x 3-4 RM; II-3 x 9-10 RM; III-3 x 15-16 RM; IV, control. Participants: 48 apparently-healthy young men (18 to 34 years of age, X = 23.2) who had not participated in systematic heavy-resistance training during the previous year. Measures: Pre and post velocity-spectrum tests were conducted for both the squat (0.41, 0.65, 0.90, 1.14, and 1.39 m x s(-1) and bench press (0.50, 0.79, 1.09, 1.39 and 1.69 m x s-1) at which time peak force and peak power were measured. Force and power measurements were adjusted to control for body weight (N/kg and W/kg, respectively). Change (delta) scores were used for comparisons. Results: One-way ANOVA s indicated that when compared to controls, improvements in force were significantly (p < 0.05) greater only at the slowest velocity (squats: Group II > Control; bench presses: Groups I, II, III > Control). However, changes in power were significantly (p < 0.05) greater than for controls at all 5 velocities tested (squats: Groups I, II > Control; bench presses: Groups I, II > Control except at 1.69 m x sec-1) where only Group I > Control). Conclusions: Due to the mixed findings for force improvements consequent to the various repetition schemes, conclusions are somewhat tentative. It appears, however, that strength increases only for slow velocities in young, previously untrained men consequent to 3 months of a relatively wide range of RM schemes using variable-resistance equipment. Power, on the other hand, appears to increase in the same subjects across a velocity spectrum for both squats and bench presses when no more than 10 RM are performed per set.
Journal of Strength and Conditioning Research, Jun 1, 2020
This investigation examined the effects of footwear and sex on vertical jump displacement and joi... more This investigation examined the effects of footwear and sex on vertical jump displacement and joint power contributions. Twenty-three young adults with basketball experience performed 3 maximal countermovement vertical jumps in minimal and standard footwear. Ground reaction force and 3D kinematic data were collected during jumping. Footwear by sex analysis of variance for all dependent variables and effect sizes (d) was computed. An interaction effect showed that men produced greater lower-limb-positive work than women in standard footwear. Men jumped higher than women (d = 2.53) and produced greater peak ankle, knee and hip joint moments (d. 0.99), positive joint powers (d. 1.07) and, positive knee and hip joint work (d. 1.04) with no sex differences for negative joint powers and work (p. 0.05). Minimal footwear produced less peak-positive knee power (d = 0.27) and less positive ankle (d = 0.34) and knee (d = 0.21) joint work than standard footwear. Because negative joint power and work were similar between sexes, men may be better able to use the stretch-shortening cycle compared with women. Higher joint mechanical demands may provide a better vertical jumping training stimulus in standard compared with minimal footwear. Future studies should investigate footwear training effects on performance and joint mechanics during jumping.
Medicine and Science in Sports and Exercise, May 1, 2015
Foot anthropometric dimensions may influence moment arm lengths and respective moments of force r... more Foot anthropometric dimensions may influence moment arm lengths and respective moments of force resisted by skeletal muscles. Depending upon circumstances, absolute or normalized expressions of these measures may have greater utility. PURPOSE: To determine the stability reliability and precision of two absolute and normalized moment arm lengths of the foot. METHODS: Longitudinal foot dimensions were obtained in 27 men and 27 women including the anterior-posterior distance between the posterior calcaneus and: 1) talocrural (TALO) and 2) metatarsophalangeal (META) joints. Bilateral measurements of seated subjects were performed using a digital sliding caliper. Absolute dimensions were normalized to height and lower-limb length (LLL, greater trochanter to lateral malleolus). Measures were obtained twice, separated by either 24 or 48 hours. Stability reliability was determined using intraclass correlation coefficient (ICC), and precision using standard error of measurement (SEM). RESULTS: The scatter of points around the trend lines for all 54 subjects combined appear to be uniform and the separate SEMs for men and women are similar. Assuming homoscedasticity, data are reported for the combined groups. For the 3 bilateral expressions of the 2 foot dimensions (12 measures), the low and high means (standard deviation) are reported for each session as well as the ICC and SEM for the pair of sessions. For TALO, means were 5.1 (0.4) and 5.2 (0.5) cm, ICCs were 0.79 and 0.82, and SEMs were 0.2 and 0.2. When normalized to height, means were 0.030 (0.002) and 0.030 (0.002) cm/cm height, ICCs were 0.65 and 0.75, and SEMs were 0.001 and 0.001. When normalized to LLL, means were 0.062 (0.005) and 0.063 (0.005) cm/cm LLL, ICCs were 0.69 and 0.73, and SEMs were 0.003 and 0.003. For META, means were 17.0 (1.2) and 17.1 (1.1) cm, ICCs were 0.97 and 0.98, and SEMs were 0.2 and 0.2. When normalized to height, means were 0.098 (0.002) and 0.100 (0.002) cm/cm height, ICCs were 0.92 and 0.94, and SEMs were 0.001 and 0.001. When normalized to LLL, means were 0.205 (0.010) and 0.208 (0.011) cm/cm LLL, ICCs were 0.92 and 0.92, and SEMs were 0.003 and 0.003. CONCLUSIONS: Surface landmarks and digital calipers can be used to precisely measure the 2 foot dimensions in question, whether or not they are normalized. Reliability is high for the META dimension, and lower for the TALO dimension. Meticulous data acquisition protocols are required to acquire potentially useful data.
Journal of Strength and Conditioning Research, 2002
Currently, variables predictive of vertical jumping performance can account for only part of its ... more Currently, variables predictive of vertical jumping performance can account for only part of its total variability. A potential additional source of variation called explosive strength deficit (ESD) was described in 1995 by Zatsiorsky (Science and Practice of Strength Training. Champaign, IL: Human Kinetics, 1995. pp. 34-35.). ESD is determined by measuring the maximum force generated under ideal circumstances (F mm) and under task-relevant conditions (F m). It is calculated as 100(F mm Ϫ F m)/F m. For this study, the following operational definitions were used: F mm ϭ squatting peak force at 0.51 m•s Ϫ1 ; F m ϭ squatting peak force at 1.43 m•s Ϫ1. Data were analyzed using forward stepwise multiple regression. Mean ESD for men was 29.7% (SD ϭ 11.7) and for women was 49.3% (SD ϭ 11.2). For men and women, respectively, zero-order correlations for ESD with restricted vertical jumping (RVJ) distance were Ϫ0.35 and Ϫ0.60, and between ESD and drop vertical jumping (DVJ) distance were Ϫ0.20 and Ϫ0.63. However, when the previously identified predictors were taken into account, ESD was not a significant predictor (p Ͼ 0.05) of either type of jump. Therefore, it was concluded that ESD on the basis of velocity-regulated squats does not augment the explained variance previously established for vertical jumping performance.
Human Movement Science, Aug 1, 2020
Running promotes better cardiovascular health and has positive effects on the musculoskeletal sys... more Running promotes better cardiovascular health and has positive effects on the musculoskeletal system in older adults. However, older adults have lower ankle plantarflexor torques and positive powers during running, and exhibit changes in plantarflexor morphology than young adults. Since older runners who run as much as younger runners exhibit youthful ankle mechanical outputs, running exposure may preserve the locomotor factors that mediate running speed. The purpose of this study was to compare ankle mechanical output during running and plantarflexor morphological characteristics between older runners who have low or high lifetime running exposure. Ten older runners with low lifetime running exposure and nine older runners with high lifetime running exposure performed over-ground running trials at 3.0 m/s (±5%) while kinematic and ground reaction force (GRF) data were collected and used to compute joint angular kinetics. Right medial gastrocnemius morphological characteristics were assessed using ultrasonography at rest and during isometric contractions. Ankle torques, powers, and plantarflexor morphology were compared between groups. Older runners with different lifetime running exposures ran with similar ankle mechanical output (i.e. no effect of running exposure) (p > .05) and exhibited similar medial gastrocnemius morphology during isometric testing. The findings from this study demonstrate that lifetime running exposure does not appear to influence ankle mechanical output or plantarflexor morphology in middle-aged runners.
Journal of Strength and Conditioning Research, 2000
Page 1. 241 Journal of Strength and Conditioning Research, 2000, 14(3), 241247 2000 National Str... more Page 1. 241 Journal of Strength and Conditioning Research, 2000, 14(3), 241247 2000 National Strength & Conditioning Association Comparative Effects of Deep Versus Shallow Squat and Leg-Press Training on Vertical Jumping Ability and Related Factors ...
Perceptual and Motor Skills, Aug 1, 2006
Summa y.-The effects of contextual interference on learning pistol-shooting skills in a natural t... more Summa y.-The effects of contextual interference on learning pistol-shooting skills in a natural training environment were examined. The shooting skills consisted of three "stages" with different requirements for the skill variations commonly used in the field. 12 participants were randomly assigned into one of two practice conditions, blocked vs serial. Following a 20-min. safety and skill instructional session, Blocked group practiced 10 trials in a row at each stage, while Serial group performed 5 trials in a row for each of the three stages and then repeated the cycle. Both groups completed a total of 30 practice trials over the three stages. A 10-min. rest interval was provided prior to a retention test which included 9 trials (3 trials at each stage in a blocked format). Results based on the data of Stage 111, the most complex skill among the three stages, showed a pattern consistent with previous findings that practicing in the serial schedule depressed performance during initial training but maintained the performance better at retention, relative to the blocked practice. 'The authors thank all participants who volunteered for the study. Special thanks are extended 50 Mr. William John Keller for his assistance in data collection.
Journal of Strength and Conditioning Research, 2021
ABSTRACT Daugherty, HJ, Weiss, LW, Paquette, MR, Powell, DW, and Allison, LE. Potential predictor... more ABSTRACT Daugherty, HJ, Weiss, LW, Paquette, MR, Powell, DW, and Allison, LE. Potential predictors of vertical jump performance: Lower extremity dimensions and alignment, relative body fat, and kinetic variables. J Strength Cond Res 35(3): 616-625, 2021-The association of structural and kinetic variables with restricted vertical jump (RVJ) displacement without and with added mass was examined in 60 men and women. Added mass (weighted vest) simulated a 5% increase in body fat (BF%). Independent variables included BF%, thigh length, and static Q-angle (Q-angles), and while performing RVJ, different expressions of frontal-plane knee angle (FPKA), dynamic Q-angle (Q-angled), vertical ground reaction force (vGRF), concentric vertical impulse (Iz), concentric rate of force development (CRFD), and vertical power (Pz). Variables having significant (p ≤ 0.05) negative correlations with RVJ displacement included BF% (r = -0.76) and Q-angles (r = -0.55). Those having significant (p ≤ 0.05) positive correlations with RVJ displacement included peak and average concentric Pz (r range = 0.74-0.81), peak and average concentric vGRF (r range = 0.46-0.67), Iz (r range = 0.32-0.54), thigh length (r = 0.31), minimum Q-angled (r = 0.31), and maximum FPKA (r = 0.28). Variables not associated (p > 0.05) with RVJ displacement included minimum and excursion FPKA (r = 0.11 and 0.23), maximum, excursion, and average Q-angled (r = 0.24, 0.11, and 0.22), and CRFD (r range = 0.19-0.24). A simple regression model predicted RVJ displacement (p = 1.00) for the simulated 5% increase in body fat. To maximize jumping performance, (a) high levels of body fat should be avoided, (b) peak and average Pz, vGRF, and Iz should be maximized through training, and (c) having a lower Q-angles is associated with better jumping ability.
Medicine & Science in Sports & Exercise, 2015
Foot anthropometric dimensions may influence moment arm lengths and respective moments of force r... more Foot anthropometric dimensions may influence moment arm lengths and respective moments of force resisted by skeletal muscles. Depending upon circumstances, absolute or normalized expressions of these measures may have greater utility. PURPOSE: To determine the stability reliability and precision of two absolute and normalized moment arm lengths of the foot. METHODS: Longitudinal foot dimensions were obtained in 27 men and 27 women including the anterior-posterior distance between the posterior calcaneus and: 1) talocrural (TALO) and 2) metatarsophalangeal (META) joints. Bilateral measurements of seated subjects were performed using a digital sliding caliper. Absolute dimensions were normalized to height and lower-limb length (LLL, greater trochanter to lateral malleolus). Measures were obtained twice, separated by either 24 or 48 hours. Stability reliability was determined using intraclass correlation coefficient (ICC), and precision using standard error of measurement (SEM). RESULTS: The scatter of points around the trend lines for all 54 subjects combined appear to be uniform and the separate SEMs for men and women are similar. Assuming homoscedasticity, data are reported for the combined groups. For the 3 bilateral expressions of the 2 foot dimensions (12 measures), the low and high means (standard deviation) are reported for each session as well as the ICC and SEM for the pair of sessions. For TALO, means were 5.1 (0.4) and 5.2 (0.5) cm, ICCs were 0.79 and 0.82, and SEMs were 0.2 and 0.2. When normalized to height, means were 0.030 (0.002) and 0.030 (0.002) cm/cm height, ICCs were 0.65 and 0.75, and SEMs were 0.001 and 0.001. When normalized to LLL, means were 0.062 (0.005) and 0.063 (0.005) cm/cm LLL, ICCs were 0.69 and 0.73, and SEMs were 0.003 and 0.003. For META, means were 17.0 (1.2) and 17.1 (1.1) cm, ICCs were 0.97 and 0.98, and SEMs were 0.2 and 0.2. When normalized to height, means were 0.098 (0.002) and 0.100 (0.002) cm/cm height, ICCs were 0.92 and 0.94, and SEMs were 0.001 and 0.001. When normalized to LLL, means were 0.205 (0.010) and 0.208 (0.011) cm/cm LLL, ICCs were 0.92 and 0.92, and SEMs were 0.003 and 0.003. CONCLUSIONS: Surface landmarks and digital calipers can be used to precisely measure the 2 foot dimensions in question, whether or not they are normalized. Reliability is high for the META dimension, and lower for the TALO dimension. Meticulous data acquisition protocols are required to acquire potentially useful data.
Journal of strength and conditioning research / National Strength & Conditioning Association, Jan 3, 2016
Vertical jump (VJ) capability is integral to the level of success attained by individuals partici... more Vertical jump (VJ) capability is integral to the level of success attained by individuals participating in numerous sport and physical activities. Knowledge of factors related to jump performance may help with talent identification and/or optimizing training prescription. Although myriad variables are likely related to VJ, this study focused on determining if various lower-body dimensions and/or body composition would explain some of the variability in performance. Selected anthropometric dimensions were obtained from 50 university students (25 men and 25 women) on two occasions separated by 48 or 72 hours. Estimated body fat percentage (BF%), height, body weight, hip width, pelvic width, bilateral quadriceps angle (Q-angle), and bilateral longitudinal dimensions of the feet, leg, thigh, and lower limb were obtained. Additionally, participants completed countermovement VJs. Analysis showed BF% to have the highest correlation with countermovement VJ displacement (r = -0.76, p < 0....
Journal of strength and conditioning research / National Strength & Conditioning Association, Jan 29, 2016
Body dimensions may influence various types of physical performance. This study was designed to e... more Body dimensions may influence various types of physical performance. This study was designed to establish the reliability and precision of bilateral lower-body dimensions using surface anatomic landmarks and either sliding calipers or goniometry. Fifty university students (25 men and 25 women) were measured on two separate occasions separated by 48 or 72 hours. A small digital caliper was used to acquire longitudinal dimensions of the feet, while a larger broad-blade caliper was used to measure lower-limb, hip, and pelvic dimensions. Quadriceps angle (Q-angle) was determined via surface goniometry. Data for all foot and lower-limb dimensions were both reliable and precise (intraclass correlation coefficient ≥ 0.72, standard error of measurement 0.1 - 0.5 cm). Measures of Q-angle were also reliable and precise (intraclass correlation coefficient ≥ 0.85, standard error of measurement 0.2 - 0.4 degrees). Findings from this investigation demonstrate that lower-body dimensions may be rel...
Military Medicine, 2012
The current U.S. Navy Physical Readiness Test (PRT) measures aerobic fitness and muscular enduran... more The current U.S. Navy Physical Readiness Test (PRT) measures aerobic fitness and muscular endurance via a 1½ mile run and curl-up/push-up tests, respectively. Nine new modalities were recommended to either replace or supplement the current PRT. Personnel and civilians (N = 179) were recruited from a local Navy base and participated in all modalities (duplicate if possible) over 4 weeks following familiarization sessions. Subjects performed single-leg plank, single-leg wall squat, cadence push-ups, leg/hip dynamometer, standing long jump, and pro-agility test. Cardiovascular modalities were also performed via the 300-yard shuttle, 2-km row, and 5-km bike. Performance in the modalities was correlated to the subjects' existing PRT scores as well as within the new modalities. Although most modalities could not be concretely recommended, the plank and wall squat were eliminated from consideration because of poor reliability scores. The strongest correlation existed between the standing long jump and pro-agility test for the entire sample. Correlation scores were also analyzed by gender. The cardiovascular modalities did not have strong enough scores to elicit a recommendation to replace the 1½ mile run, but future considerations for similar testing would be to collect scores for the existing modalities in addition to the proposed modalities.
Journal of Strength and Conditioning Research, Feb 1, 1997
ABSTRACT Two equations were developed to predict distance in a restricted standing vertical jump ... more ABSTRACT Two equations were developed to predict distance in a restricted standing vertical jump (RVJ). Body composition and strength related variables generated via velocity-spectrum squats were obtained on 52 men and 50 women. Eight squat variables at 4 velocities were selected as potential predictors of RVJ performance. These variables along with body weight, body fat, and gender were used to generate two explanatory regressions. R values ranged from 0.80 to 0.83, and SEE ranged from 0.045 to 0.048 meters for the two equations. Variables with a positive relationship to RVJ were relative peak power at each individual's optimal velocity for power production and at 1.43 m [middle dot] s-1. Variables with a negative relationship were relative peak force and % body fat. It appears that (a) the more relative squatting power a person can generate at moderately fast squatting velocities, the greater the RVJ distance; and (b) excessive body fat and the ability to generate high relative squatting forces at slow velocities attenuate the predicted distance. (C) 1997 National Strength and Conditioning Association
Research in Sports Medicine, 2003
To determine the effects of 12 weeks of resistance exercise with MyoVive and/or colostrum supplem... more To determine the effects of 12 weeks of resistance exercise with MyoVive and/or colostrum supplementation, 19 male and female recreationally weighttrained subjects (X ± SE; age = 28.3 ± 6.9 yrs; hgt = 68.2 ± 3.8 cm) were divided into MyoVive + colostrum (n = 4), MyoVive + casein & whey (n = 4), colostrum + casein & whey (n = 6), and casein & whey (n = 5) groups. All groups similarly increased (p < .05) 1 repetition maximum (RM) leg press (kg; pre = 158.6 ± 12.8, post = 189.3 ± 11.3), body mass (kg; pre = 79.0 ± 3.2, post = 80.7 ± 3.8), and lean body mass (kg; pre = 60.1 ± 3.1, post = 62.2 ± 2.8). Increases were observed for peak force (N; all loads), peak velocity (m. s-1 ; 70% & 40% 1 RM), and peak power (W; 70% & 40% 1 RM) for all groups for the leg press exercise, with no differences between groups. When performance data were adjusted for body mass, lean body mass, lower body lean mass as determined by DEXA, or % change, no group differences were observed. Relative (%) fiber type content, cross-sectional areas (mm 2), % fiber type areas, or % myosin heavy chain expression did not change for any group. These data suggest that MyoVive and colostrum supplementation have no greater effect on cellular and performance adaptations when compared to casein and whey protein.
Isokinetics and Exercise Science, 1998
Journal of strength and conditioning research, Jan 2, 2018
Smith, RE, Paquette, MR, Harry, JR, Powell, DW, and Weiss, LW. Footwear and sex differences in pe... more Smith, RE, Paquette, MR, Harry, JR, Powell, DW, and Weiss, LW. Footwear and sex differences in performance and joint kinetics during maximal vertical jumping. J Strength Cond Res XX(X): 000-000, 2018-This investigation examined the effects of footwear and sex on vertical jump displacement and joint power contributions. Twenty-three young adults with basketball experience performed 3 maximal countermovement vertical jumps in minimal and standard footwear. Ground reaction force and 3D kinematic data were collected during jumping. Footwear by sex analysis of variance for all dependent variables and effect sizes (d) was computed. An interaction effect showed that men produced greater lower-limb-positive work than women in standard footwear. Men jumped higher than women (d = 2.53) and produced greater peak ankle, knee and hip joint moments (d > 0.99), positive joint powers (d > 1.07) and, positive knee and hip joint work (d > 1.04) with no sex differences for negative joint powe...
Journal of Strength and Conditioning Research, 2015
Harry, JR, Paquette, MR, Caia, J, Townsend, RJ, Weiss, LW, and Schilling, BK. Effects of footwear... more Harry, JR, Paquette, MR, Caia, J, Townsend, RJ, Weiss, LW, and Schilling, BK. Effects of footwear condition on maximal jumping performance. J Strength Cond Res 29(6): 1657-1665, 2015-The purpose of this investigation was to examine the effects of footwear on kinetics and lower extremity electromyographic (EMG) activity during the vertical jump (VJ) and standing long jump. Fifteen men performed the 2 jump types in 3 footwear conditions: barefoot, minimal shoes, and crosstraining shoes. Jump displacement and kinetic data were collected, along with EMG activity of the biceps femoris, medial gastrocnemius, peroneus longus, semitendinosus/semimembranosus, soleus (SOL), tibialis anterior, vastus lateralis, and vastus medialis. Subjective footwear performance and comfort were also assessed with a custom survey. No differences were found in jump displacement, peak ground reaction forces (GRF), countermovement and propulsive phase durations, vertical impulse, peak countermovement, or average propulsive EMG activity. Significant differences in peak propulsive root mean square EMG were found between barefoot and minimal shoes (p = 0.030) and minimal shoes and shod (p = 0.031) conditions for the SOL during the VJ, and for average countermovement EMG of the semitendinosus/semimembranosus during the VJ between barefoot and shod (p = 0.039). Moderate-to-large effect sizes (.0.59) were found between conditions for horizontal GRF, propulsive phase duration, average EMG amplitude, and duration of EMG activity during the countermovement. Participants reported higher comfort ratings when shod compared with barefoot and minimal shoes for both jumps. Participants also perceived better performance when shod compared with barefoot and minimal shoes for the VJ only. No acute differences in displacement were observed between barefoot, minimal shoes, and cross-trainer shoes during vertical and horizontal jumps. Some differences in muscle activation and timing seem to be present, and thus, training effects between footwear conditions should be examined. Footwear familiarization may prove beneficial, as acute increases in comfort seem unrelated to performance improvements. *SLJ = standing long jump; VJ = vertical jump; GRFz = vertical ground reaction force; GRFy = horizontal ground reaction force; ES = effect size. †Mean 6 SD for kinetic data: peak vertical ground reaction force (Peak GRFz) and peak horizontal ground reaction force (Peak GRFy 3 bodyweight), countermovement and propulsive phase duration (seconds), countermovement and propulsive impulse (N$s) for the barefoot, minimal shoes, and cross-training shoes (shod) are presented for the SLJ and VJ tests. Moderate-to-large ESs were found during the VJ for peak GRFy (barefoot vs. shod), propulsive phase duration (barefoot vs. shod; minimal shoes vs. shod), and countermovement impulse (barefoot vs. shod; minimal shoes vs. shod).
Journal of Strength and Conditioning Research, Sep 1, 2016
Body dimensions may influence various types of physical performance. This study was designed to e... more Body dimensions may influence various types of physical performance. This study was designed to establish the reliability and precision of bilateral lower-body dimensions using surface anatomic landmarks and either sliding calipers or goniometry. Fifty university students (25 men and 25 women) were measured on two separate occasions separated by 48 or 72 hours. A small digital caliper was used to acquire longitudinal dimensions of the feet, while a larger broad-blade caliper was used to measure lower-limb, hip, and pelvic dimensions. Quadriceps angle (Q-angle) was determined via surface goniometry. Data for all foot and lower-limb dimensions were both reliable and precise (intraclass correlation coefficient ≥ 0.72, standard error of measurement 0.1-0.5 cm). Measures of Q-angle were also reliable and precise (intraclass correlation coefficient ≥ 0.85, standard error of measurement 0.2-0.4 degrees). Findings from this investigation demonstrate that lower-body dimensions may be reliably and precisely measured via simple practical tests, when surface anatomic landmarks and standardized procedures are used. Although inter-tester reliability remains to be established, meticulous adherence to specific measurement protocols is likely to yield viable output for lower-body dimensions when more sophisticated methods are unavailable or inappropriate.
Isokinetics and Exercise Science, Oct 1, 1998
Isokinetics and Exercise Science, Oct 1, 1997
Two force and two power variables were monitored during standardized multiple-joint, closed-chain... more Two force and two power variables were monitored during standardized multiple-joint, closed-chain, velocity-spectrum tests to ascertain if contiguous velocities produced discrete or redundant output. Measurements were obtained from 52 men and 50 women during squats performed at six velocities ranging from 0.51 to 2.04 m· S-l. Main effects as well as the sex-by-main-effects interaction were significant (P < 0.001) for all four variables. Therefore, post hoc tests were performed separately for men and women. Maximal squatting forces over the velocity spectrum produced force-velocity curves resembling classical single-joint ones. The highest force output occurred at the slowest test velocity as expected and signifcantly decreased (P < 0.05) for each increment in velocity for both men and women. Concurrently, maximal squatting power over the velocity spectrum produced power-velocity curves resembling classical single-joint ones. The highest power output (x = 1.26 m . S-l) occurred as part of a plateau at intermediate velocities as expected and was signifcantly less at faster and slower velocities. However, maximal power output generally materialized at faster velocities for men (x = 1.54 m·s- 1 ) than for women (x = 0.97 m·s- 1 ). It appears the six squatting velocities used in this investigation elicit discrete force data for both men and women, and results for force and power resemble what would be expected for isolated single-joint testing protocols. However, it remains unclear why an apparent gender difference exists in the velocity at which the highest peak power is produced.
PubMed, Mar 1, 2001
Background: Various repetition strategies are employed in typical weight-training programs. Stren... more Background: Various repetition strategies are employed in typical weight-training programs. Strength is purportedly best developed using relatively few repetitions against great resistance. Strength in this context has typically been measured isotonically (dynamic constant external resistance or DCER) by performing a one-repetition maximum (1 RM). Multiple-joint isokinetic (velocity controlled) strength assessments are now available which may enable us to emulate movement patterns and velocities with those occurring in everyday activities while providing us with force and power information that heretofore has been difficult to obtain. Therefore, we assessed the effects of various repetition schemes during heavy-resistance training on multiple-joint isokinetic performance. METHODS. Setting: Volunteers participated in 12 weeks (36 sessions) of variable-resistance weight training (8 different exercises) in one of the following programs: I-3 sets x 3-4 RM; II-3 x 9-10 RM; III-3 x 15-16 RM; IV, control. Participants: 48 apparently-healthy young men (18 to 34 years of age, X = 23.2) who had not participated in systematic heavy-resistance training during the previous year. Measures: Pre and post velocity-spectrum tests were conducted for both the squat (0.41, 0.65, 0.90, 1.14, and 1.39 m x s(-1) and bench press (0.50, 0.79, 1.09, 1.39 and 1.69 m x s-1) at which time peak force and peak power were measured. Force and power measurements were adjusted to control for body weight (N/kg and W/kg, respectively). Change (delta) scores were used for comparisons. Results: One-way ANOVA s indicated that when compared to controls, improvements in force were significantly (p < 0.05) greater only at the slowest velocity (squats: Group II > Control; bench presses: Groups I, II, III > Control). However, changes in power were significantly (p < 0.05) greater than for controls at all 5 velocities tested (squats: Groups I, II > Control; bench presses: Groups I, II > Control except at 1.69 m x sec-1) where only Group I > Control). Conclusions: Due to the mixed findings for force improvements consequent to the various repetition schemes, conclusions are somewhat tentative. It appears, however, that strength increases only for slow velocities in young, previously untrained men consequent to 3 months of a relatively wide range of RM schemes using variable-resistance equipment. Power, on the other hand, appears to increase in the same subjects across a velocity spectrum for both squats and bench presses when no more than 10 RM are performed per set.
Journal of Strength and Conditioning Research, Jun 1, 2020
This investigation examined the effects of footwear and sex on vertical jump displacement and joi... more This investigation examined the effects of footwear and sex on vertical jump displacement and joint power contributions. Twenty-three young adults with basketball experience performed 3 maximal countermovement vertical jumps in minimal and standard footwear. Ground reaction force and 3D kinematic data were collected during jumping. Footwear by sex analysis of variance for all dependent variables and effect sizes (d) was computed. An interaction effect showed that men produced greater lower-limb-positive work than women in standard footwear. Men jumped higher than women (d = 2.53) and produced greater peak ankle, knee and hip joint moments (d. 0.99), positive joint powers (d. 1.07) and, positive knee and hip joint work (d. 1.04) with no sex differences for negative joint powers and work (p. 0.05). Minimal footwear produced less peak-positive knee power (d = 0.27) and less positive ankle (d = 0.34) and knee (d = 0.21) joint work than standard footwear. Because negative joint power and work were similar between sexes, men may be better able to use the stretch-shortening cycle compared with women. Higher joint mechanical demands may provide a better vertical jumping training stimulus in standard compared with minimal footwear. Future studies should investigate footwear training effects on performance and joint mechanics during jumping.
Medicine and Science in Sports and Exercise, May 1, 2015
Foot anthropometric dimensions may influence moment arm lengths and respective moments of force r... more Foot anthropometric dimensions may influence moment arm lengths and respective moments of force resisted by skeletal muscles. Depending upon circumstances, absolute or normalized expressions of these measures may have greater utility. PURPOSE: To determine the stability reliability and precision of two absolute and normalized moment arm lengths of the foot. METHODS: Longitudinal foot dimensions were obtained in 27 men and 27 women including the anterior-posterior distance between the posterior calcaneus and: 1) talocrural (TALO) and 2) metatarsophalangeal (META) joints. Bilateral measurements of seated subjects were performed using a digital sliding caliper. Absolute dimensions were normalized to height and lower-limb length (LLL, greater trochanter to lateral malleolus). Measures were obtained twice, separated by either 24 or 48 hours. Stability reliability was determined using intraclass correlation coefficient (ICC), and precision using standard error of measurement (SEM). RESULTS: The scatter of points around the trend lines for all 54 subjects combined appear to be uniform and the separate SEMs for men and women are similar. Assuming homoscedasticity, data are reported for the combined groups. For the 3 bilateral expressions of the 2 foot dimensions (12 measures), the low and high means (standard deviation) are reported for each session as well as the ICC and SEM for the pair of sessions. For TALO, means were 5.1 (0.4) and 5.2 (0.5) cm, ICCs were 0.79 and 0.82, and SEMs were 0.2 and 0.2. When normalized to height, means were 0.030 (0.002) and 0.030 (0.002) cm/cm height, ICCs were 0.65 and 0.75, and SEMs were 0.001 and 0.001. When normalized to LLL, means were 0.062 (0.005) and 0.063 (0.005) cm/cm LLL, ICCs were 0.69 and 0.73, and SEMs were 0.003 and 0.003. For META, means were 17.0 (1.2) and 17.1 (1.1) cm, ICCs were 0.97 and 0.98, and SEMs were 0.2 and 0.2. When normalized to height, means were 0.098 (0.002) and 0.100 (0.002) cm/cm height, ICCs were 0.92 and 0.94, and SEMs were 0.001 and 0.001. When normalized to LLL, means were 0.205 (0.010) and 0.208 (0.011) cm/cm LLL, ICCs were 0.92 and 0.92, and SEMs were 0.003 and 0.003. CONCLUSIONS: Surface landmarks and digital calipers can be used to precisely measure the 2 foot dimensions in question, whether or not they are normalized. Reliability is high for the META dimension, and lower for the TALO dimension. Meticulous data acquisition protocols are required to acquire potentially useful data.
Journal of Strength and Conditioning Research, 2002
Currently, variables predictive of vertical jumping performance can account for only part of its ... more Currently, variables predictive of vertical jumping performance can account for only part of its total variability. A potential additional source of variation called explosive strength deficit (ESD) was described in 1995 by Zatsiorsky (Science and Practice of Strength Training. Champaign, IL: Human Kinetics, 1995. pp. 34-35.). ESD is determined by measuring the maximum force generated under ideal circumstances (F mm) and under task-relevant conditions (F m). It is calculated as 100(F mm Ϫ F m)/F m. For this study, the following operational definitions were used: F mm ϭ squatting peak force at 0.51 m•s Ϫ1 ; F m ϭ squatting peak force at 1.43 m•s Ϫ1. Data were analyzed using forward stepwise multiple regression. Mean ESD for men was 29.7% (SD ϭ 11.7) and for women was 49.3% (SD ϭ 11.2). For men and women, respectively, zero-order correlations for ESD with restricted vertical jumping (RVJ) distance were Ϫ0.35 and Ϫ0.60, and between ESD and drop vertical jumping (DVJ) distance were Ϫ0.20 and Ϫ0.63. However, when the previously identified predictors were taken into account, ESD was not a significant predictor (p Ͼ 0.05) of either type of jump. Therefore, it was concluded that ESD on the basis of velocity-regulated squats does not augment the explained variance previously established for vertical jumping performance.
Human Movement Science, Aug 1, 2020
Running promotes better cardiovascular health and has positive effects on the musculoskeletal sys... more Running promotes better cardiovascular health and has positive effects on the musculoskeletal system in older adults. However, older adults have lower ankle plantarflexor torques and positive powers during running, and exhibit changes in plantarflexor morphology than young adults. Since older runners who run as much as younger runners exhibit youthful ankle mechanical outputs, running exposure may preserve the locomotor factors that mediate running speed. The purpose of this study was to compare ankle mechanical output during running and plantarflexor morphological characteristics between older runners who have low or high lifetime running exposure. Ten older runners with low lifetime running exposure and nine older runners with high lifetime running exposure performed over-ground running trials at 3.0 m/s (±5%) while kinematic and ground reaction force (GRF) data were collected and used to compute joint angular kinetics. Right medial gastrocnemius morphological characteristics were assessed using ultrasonography at rest and during isometric contractions. Ankle torques, powers, and plantarflexor morphology were compared between groups. Older runners with different lifetime running exposures ran with similar ankle mechanical output (i.e. no effect of running exposure) (p > .05) and exhibited similar medial gastrocnemius morphology during isometric testing. The findings from this study demonstrate that lifetime running exposure does not appear to influence ankle mechanical output or plantarflexor morphology in middle-aged runners.
Journal of Strength and Conditioning Research, 2000
Page 1. 241 Journal of Strength and Conditioning Research, 2000, 14(3), 241247 2000 National Str... more Page 1. 241 Journal of Strength and Conditioning Research, 2000, 14(3), 241247 2000 National Strength & Conditioning Association Comparative Effects of Deep Versus Shallow Squat and Leg-Press Training on Vertical Jumping Ability and Related Factors ...
Perceptual and Motor Skills, Aug 1, 2006
Summa y.-The effects of contextual interference on learning pistol-shooting skills in a natural t... more Summa y.-The effects of contextual interference on learning pistol-shooting skills in a natural training environment were examined. The shooting skills consisted of three "stages" with different requirements for the skill variations commonly used in the field. 12 participants were randomly assigned into one of two practice conditions, blocked vs serial. Following a 20-min. safety and skill instructional session, Blocked group practiced 10 trials in a row at each stage, while Serial group performed 5 trials in a row for each of the three stages and then repeated the cycle. Both groups completed a total of 30 practice trials over the three stages. A 10-min. rest interval was provided prior to a retention test which included 9 trials (3 trials at each stage in a blocked format). Results based on the data of Stage 111, the most complex skill among the three stages, showed a pattern consistent with previous findings that practicing in the serial schedule depressed performance during initial training but maintained the performance better at retention, relative to the blocked practice. 'The authors thank all participants who volunteered for the study. Special thanks are extended 50 Mr. William John Keller for his assistance in data collection.
Journal of Strength and Conditioning Research, 2021
ABSTRACT Daugherty, HJ, Weiss, LW, Paquette, MR, Powell, DW, and Allison, LE. Potential predictor... more ABSTRACT Daugherty, HJ, Weiss, LW, Paquette, MR, Powell, DW, and Allison, LE. Potential predictors of vertical jump performance: Lower extremity dimensions and alignment, relative body fat, and kinetic variables. J Strength Cond Res 35(3): 616-625, 2021-The association of structural and kinetic variables with restricted vertical jump (RVJ) displacement without and with added mass was examined in 60 men and women. Added mass (weighted vest) simulated a 5% increase in body fat (BF%). Independent variables included BF%, thigh length, and static Q-angle (Q-angles), and while performing RVJ, different expressions of frontal-plane knee angle (FPKA), dynamic Q-angle (Q-angled), vertical ground reaction force (vGRF), concentric vertical impulse (Iz), concentric rate of force development (CRFD), and vertical power (Pz). Variables having significant (p ≤ 0.05) negative correlations with RVJ displacement included BF% (r = -0.76) and Q-angles (r = -0.55). Those having significant (p ≤ 0.05) positive correlations with RVJ displacement included peak and average concentric Pz (r range = 0.74-0.81), peak and average concentric vGRF (r range = 0.46-0.67), Iz (r range = 0.32-0.54), thigh length (r = 0.31), minimum Q-angled (r = 0.31), and maximum FPKA (r = 0.28). Variables not associated (p > 0.05) with RVJ displacement included minimum and excursion FPKA (r = 0.11 and 0.23), maximum, excursion, and average Q-angled (r = 0.24, 0.11, and 0.22), and CRFD (r range = 0.19-0.24). A simple regression model predicted RVJ displacement (p = 1.00) for the simulated 5% increase in body fat. To maximize jumping performance, (a) high levels of body fat should be avoided, (b) peak and average Pz, vGRF, and Iz should be maximized through training, and (c) having a lower Q-angles is associated with better jumping ability.
Medicine & Science in Sports & Exercise, 2015
Foot anthropometric dimensions may influence moment arm lengths and respective moments of force r... more Foot anthropometric dimensions may influence moment arm lengths and respective moments of force resisted by skeletal muscles. Depending upon circumstances, absolute or normalized expressions of these measures may have greater utility. PURPOSE: To determine the stability reliability and precision of two absolute and normalized moment arm lengths of the foot. METHODS: Longitudinal foot dimensions were obtained in 27 men and 27 women including the anterior-posterior distance between the posterior calcaneus and: 1) talocrural (TALO) and 2) metatarsophalangeal (META) joints. Bilateral measurements of seated subjects were performed using a digital sliding caliper. Absolute dimensions were normalized to height and lower-limb length (LLL, greater trochanter to lateral malleolus). Measures were obtained twice, separated by either 24 or 48 hours. Stability reliability was determined using intraclass correlation coefficient (ICC), and precision using standard error of measurement (SEM). RESULTS: The scatter of points around the trend lines for all 54 subjects combined appear to be uniform and the separate SEMs for men and women are similar. Assuming homoscedasticity, data are reported for the combined groups. For the 3 bilateral expressions of the 2 foot dimensions (12 measures), the low and high means (standard deviation) are reported for each session as well as the ICC and SEM for the pair of sessions. For TALO, means were 5.1 (0.4) and 5.2 (0.5) cm, ICCs were 0.79 and 0.82, and SEMs were 0.2 and 0.2. When normalized to height, means were 0.030 (0.002) and 0.030 (0.002) cm/cm height, ICCs were 0.65 and 0.75, and SEMs were 0.001 and 0.001. When normalized to LLL, means were 0.062 (0.005) and 0.063 (0.005) cm/cm LLL, ICCs were 0.69 and 0.73, and SEMs were 0.003 and 0.003. For META, means were 17.0 (1.2) and 17.1 (1.1) cm, ICCs were 0.97 and 0.98, and SEMs were 0.2 and 0.2. When normalized to height, means were 0.098 (0.002) and 0.100 (0.002) cm/cm height, ICCs were 0.92 and 0.94, and SEMs were 0.001 and 0.001. When normalized to LLL, means were 0.205 (0.010) and 0.208 (0.011) cm/cm LLL, ICCs were 0.92 and 0.92, and SEMs were 0.003 and 0.003. CONCLUSIONS: Surface landmarks and digital calipers can be used to precisely measure the 2 foot dimensions in question, whether or not they are normalized. Reliability is high for the META dimension, and lower for the TALO dimension. Meticulous data acquisition protocols are required to acquire potentially useful data.
Journal of strength and conditioning research / National Strength & Conditioning Association, Jan 3, 2016
Vertical jump (VJ) capability is integral to the level of success attained by individuals partici... more Vertical jump (VJ) capability is integral to the level of success attained by individuals participating in numerous sport and physical activities. Knowledge of factors related to jump performance may help with talent identification and/or optimizing training prescription. Although myriad variables are likely related to VJ, this study focused on determining if various lower-body dimensions and/or body composition would explain some of the variability in performance. Selected anthropometric dimensions were obtained from 50 university students (25 men and 25 women) on two occasions separated by 48 or 72 hours. Estimated body fat percentage (BF%), height, body weight, hip width, pelvic width, bilateral quadriceps angle (Q-angle), and bilateral longitudinal dimensions of the feet, leg, thigh, and lower limb were obtained. Additionally, participants completed countermovement VJs. Analysis showed BF% to have the highest correlation with countermovement VJ displacement (r = -0.76, p < 0....
Journal of strength and conditioning research / National Strength & Conditioning Association, Jan 29, 2016
Body dimensions may influence various types of physical performance. This study was designed to e... more Body dimensions may influence various types of physical performance. This study was designed to establish the reliability and precision of bilateral lower-body dimensions using surface anatomic landmarks and either sliding calipers or goniometry. Fifty university students (25 men and 25 women) were measured on two separate occasions separated by 48 or 72 hours. A small digital caliper was used to acquire longitudinal dimensions of the feet, while a larger broad-blade caliper was used to measure lower-limb, hip, and pelvic dimensions. Quadriceps angle (Q-angle) was determined via surface goniometry. Data for all foot and lower-limb dimensions were both reliable and precise (intraclass correlation coefficient ≥ 0.72, standard error of measurement 0.1 - 0.5 cm). Measures of Q-angle were also reliable and precise (intraclass correlation coefficient ≥ 0.85, standard error of measurement 0.2 - 0.4 degrees). Findings from this investigation demonstrate that lower-body dimensions may be rel...
Military Medicine, 2012
The current U.S. Navy Physical Readiness Test (PRT) measures aerobic fitness and muscular enduran... more The current U.S. Navy Physical Readiness Test (PRT) measures aerobic fitness and muscular endurance via a 1½ mile run and curl-up/push-up tests, respectively. Nine new modalities were recommended to either replace or supplement the current PRT. Personnel and civilians (N = 179) were recruited from a local Navy base and participated in all modalities (duplicate if possible) over 4 weeks following familiarization sessions. Subjects performed single-leg plank, single-leg wall squat, cadence push-ups, leg/hip dynamometer, standing long jump, and pro-agility test. Cardiovascular modalities were also performed via the 300-yard shuttle, 2-km row, and 5-km bike. Performance in the modalities was correlated to the subjects' existing PRT scores as well as within the new modalities. Although most modalities could not be concretely recommended, the plank and wall squat were eliminated from consideration because of poor reliability scores. The strongest correlation existed between the standing long jump and pro-agility test for the entire sample. Correlation scores were also analyzed by gender. The cardiovascular modalities did not have strong enough scores to elicit a recommendation to replace the 1½ mile run, but future considerations for similar testing would be to collect scores for the existing modalities in addition to the proposed modalities.
Journal of Strength and Conditioning Research, Feb 1, 1997
ABSTRACT Two equations were developed to predict distance in a restricted standing vertical jump ... more ABSTRACT Two equations were developed to predict distance in a restricted standing vertical jump (RVJ). Body composition and strength related variables generated via velocity-spectrum squats were obtained on 52 men and 50 women. Eight squat variables at 4 velocities were selected as potential predictors of RVJ performance. These variables along with body weight, body fat, and gender were used to generate two explanatory regressions. R values ranged from 0.80 to 0.83, and SEE ranged from 0.045 to 0.048 meters for the two equations. Variables with a positive relationship to RVJ were relative peak power at each individual's optimal velocity for power production and at 1.43 m [middle dot] s-1. Variables with a negative relationship were relative peak force and % body fat. It appears that (a) the more relative squatting power a person can generate at moderately fast squatting velocities, the greater the RVJ distance; and (b) excessive body fat and the ability to generate high relative squatting forces at slow velocities attenuate the predicted distance. (C) 1997 National Strength and Conditioning Association
Research in Sports Medicine, 2003
To determine the effects of 12 weeks of resistance exercise with MyoVive and/or colostrum supplem... more To determine the effects of 12 weeks of resistance exercise with MyoVive and/or colostrum supplementation, 19 male and female recreationally weighttrained subjects (X ± SE; age = 28.3 ± 6.9 yrs; hgt = 68.2 ± 3.8 cm) were divided into MyoVive + colostrum (n = 4), MyoVive + casein & whey (n = 4), colostrum + casein & whey (n = 6), and casein & whey (n = 5) groups. All groups similarly increased (p < .05) 1 repetition maximum (RM) leg press (kg; pre = 158.6 ± 12.8, post = 189.3 ± 11.3), body mass (kg; pre = 79.0 ± 3.2, post = 80.7 ± 3.8), and lean body mass (kg; pre = 60.1 ± 3.1, post = 62.2 ± 2.8). Increases were observed for peak force (N; all loads), peak velocity (m. s-1 ; 70% & 40% 1 RM), and peak power (W; 70% & 40% 1 RM) for all groups for the leg press exercise, with no differences between groups. When performance data were adjusted for body mass, lean body mass, lower body lean mass as determined by DEXA, or % change, no group differences were observed. Relative (%) fiber type content, cross-sectional areas (mm 2), % fiber type areas, or % myosin heavy chain expression did not change for any group. These data suggest that MyoVive and colostrum supplementation have no greater effect on cellular and performance adaptations when compared to casein and whey protein.
Isokinetics and Exercise Science, 1998
Journal of strength and conditioning research, Jan 2, 2018
Smith, RE, Paquette, MR, Harry, JR, Powell, DW, and Weiss, LW. Footwear and sex differences in pe... more Smith, RE, Paquette, MR, Harry, JR, Powell, DW, and Weiss, LW. Footwear and sex differences in performance and joint kinetics during maximal vertical jumping. J Strength Cond Res XX(X): 000-000, 2018-This investigation examined the effects of footwear and sex on vertical jump displacement and joint power contributions. Twenty-three young adults with basketball experience performed 3 maximal countermovement vertical jumps in minimal and standard footwear. Ground reaction force and 3D kinematic data were collected during jumping. Footwear by sex analysis of variance for all dependent variables and effect sizes (d) was computed. An interaction effect showed that men produced greater lower-limb-positive work than women in standard footwear. Men jumped higher than women (d = 2.53) and produced greater peak ankle, knee and hip joint moments (d > 0.99), positive joint powers (d > 1.07) and, positive knee and hip joint work (d > 1.04) with no sex differences for negative joint powe...