Biomedical subjects

Michael H Stone

Publications and source records attributed to Michael H Stone.

29 records · Page 2Linked to original sources

PubMed2004

Influence of familiarization on the reliability of vertical jump and acceleration sprinting performance in physically active men.

The purpose of the present study was to determine the number of familiarization sessions required to obtain an accurate measure of reliability associated with loaded vertical jump and 20-m sprint running performance. Ten physically active men attended 5 separate testing sessions over a 3-week period where they performed unloaded and loaded (10-kg extra load) countermovement (CMJ) and static (SJ) jumps, followed by straight-line 20-m sprints. Jump height was recorded for the vertical jumps using a jump mat, while the time for 10 m and 20 m was recorded during the sprints using photocells. The highest (jump conditions) and fastest (sprint) of 3 trials performed during each of the 5 testing sessions was used in the subsequent analysis. Familiarization was assessed using the scores obtained during the 5 separate testing sessions. Reliability was assessed by calculating intraclass correlation coefficients (ICCs) and coefficient of variation (CV). No significant differences were obtained between the testing sessions for any of the measures. ICCs ranged from 0.89 to 0.95, while CVs ranged from 1.9 to 2.6%. These results indicate that high levels of reliability can be achieved without the need for familiarization sessions when using loaded and unloaded CMJ and SJ and 20-m sprint performance with physically active men.

Adult↗

PubMed2004

The relationship between vertical jump power estimates and weightlifting ability: a field-test approach.

The purpose of this study was to assess the usefulness of the vertical jump and estimated vertical-jump power as a field test for weightlifting. Estimated PP output from the vertical jump was correlated with lifting ability among 64 USA national-level weightlifters (junior and senior men and women). Vertical jump was measured using the Kinematic Measurement System, consisting of a switch mat interfaced with a laptop computer. Vertical jumps were measured using a hands-on-hips method. A counter-movement vertical jump (CMJ) and a static vertical jump (SJ, 90 degrees knee angle) were measured. Two trials were given for each condition. Test-retest reliability for jump height was intra-class correlation (ICC) = 0.98 (CMJ) and ICC = 0.96 (SJ). Athletes warmed up on their own for 2-3 minutes, followed by 2 practice jumps at each condition. Peak power (PP) was estimated using the equations developed by Sayers et al. (24). The athletes' current lifting capabilities were assessed by a questionnaire, and USA national coaches checked the listed values. Differences between groups (i.e., men versus women, juniors versus resident lifters) were determined using t-tests (p < or = 0.05). Correlations were determined using Pearson's r. Results indicate that vertical jumping PP is strongly associated with weightlifting ability. Thus, these results indicate that PP derived from the vertical jump (CMJ or SJ) can be a valuable tool in assessing weightlifting performance.

Adolescent↗

PubMed2003

Borderline patients at the border of treatability: at the intersection of borderline, narcissistic, and antisocial personalities.

The author discusses the difficulties involved in treating patients with borderline personality disorder and concomitant Cluster B-narcissistic, histrionic, and/or antisocial-personality traits or disorders. He presents eight vignettes of patients with borderline personality disorder combined with various types of Cluster B personality traits or disorders and describes the course of their treatment. The author posits that such patients fall on a continuum ranging from difficult to treat but still treatable, to those with strong narcissistic or even psychopathic traits whose illness fails to improve no matter what treatment methods are applied (i.e., they have "untreatable" illness).

Journal Article↗

PubMed2003

Effects of different set configurations on barbell velocity and displacement during a clean pull.

The effects of 3 types of set configurations (cluster, traditional, and undulating) on barbell kinematics were investigated in the present study. Thirteen men (track and field = 8; Olympic weightlifters = 5) (mean +/- SEM age, 23.4 +/- 1.1 years; height, 181.3 +/- 2.1 cm; body mass, 89.8 +/- 4.2 kg) performed 1 set of 5 repetitions in a cluster, traditional, and undulating fashion at 90 and 120% of their 1 repetition maximum (1RM) power clean (119.0 +/- 4.3 kg). All data were collected at 50 Hz and analyzed with a V-Scope Weightlifting Analysis System. Peak velocity (PV) and peak displacement (PD) were analyzed for each repetition and averaged for each set type. Results indicated that a significantly (p < 0.016) higher PV occurred during the cluster set when compared with the traditional sets at both intensities. PD was significantly higher than traditional sets at the 120% intensity. The present study suggests set configuration can affect PV and PD during clean pulls.

Adult↗

PubMed2003

Power and maximum strength relationships during performance of dynamic and static weighted jumps.

The purpose of this study was to investigate the relationship of the 1 repetition maximum (1RM) squat to power output during countermovement and static weighted vertical squat jumps. The training experience of subjects (N = 22, 87.0 +/- 15.3 kg, 14.1 +/- 7.1% fat, 22.2 +/- 3.8 years) ranged from 7 weeks to 15+ years. Based on the 1RM squat, subjects were further divided into the 5 strongest and 5 weakest subjects (p <or= 0.05). Squat jumps were performed with a countermovement or statically at 2 different sessions spaced 1 week apart. Jumps were performed with weights ranging from 10 to 100% of the 1RM squat. A maximum effort was made for each trial; subjects performed jumps (feet left the floor) with weights up to approximately 90% of 1RM. Squat-jump power was determined using the V-scope 120. Results indicate strong correlations (r = 0.77-0.94) between the 1RM squat and both countermovement and static jump power up to 90% of 1RM. The highest power outputs for both jump conditions occurred at 10% of the 1RM and decreased as the relative intensity increased. Comparisons of weak and strong subjects indicate that as maximum strength increases the percentage of 1RM at which peak power occurs also increases (40 vs. 10% of 1RM). From a practical aspect, to improve jumping power output, these results suggest that improving maximum strength should be a primary component of training programs and that strength training should shift from lighter (10% 1RM) to heavier (40% 1RM) loads.

Adolescent↗

PubMed2003

Carbohydrate supplementation and resistance training.

There is a growing body of evidence suggesting that the performance of resistance-training exercises can elicit a significant glycogenolytic effect that potentially could result in performance decrements. These decrements may result in less than optimal physiological adaptations to training. Currently some scientific evidence suggests that carbohydrate supplementation prior to and during high-volume resistance training results in the maintenance of muscle glycogen concentration, which potentially could result in the maintenance or increase of performance during a training bout. Some researchers suggest that ingesting carbohydrate supplements prior to and during resistance training may improve resistance-training performance. Additionally, the ingestion of carbohydrates following resistance exercise enhances the resynthesis of muscle glycogen, which may result in a faster time of recovery from resistance training, thus possibly allowing for a greater training volume. On the basis of the current scientific literature, it may be advisable for athletes who are performing high-volume resistance training to ingest carbohydrate supplements before, during, and immediately after resistance training.

Beverages↗

PubMed2003

Effect of warm-up on the standing broad jump in trained and untrained men and women.

The effect of 3 warm-up routines on standing broad jump (SBJ) performance was investigated. Thirty-two men and women participated as subjects. Following the determination of 1-repetition maximum (1RM) squat, subjects completed warm-up routines and broad jumps on 4 occasions in a randomized order. Subjects performed SBJ immediately (POST) and 15 min following (POST15) the given warm-up routine. The routines were high force, consisting of high % 1RM, low repetition squats; high power, consisting of low % 1RM, low repetition speed squats; stretching, consisting of static stretches; and no activity, a control condition. Repeated measures analysis of covariance (ANCOVA) revealed no differences among broad jump performance following any of the warm-up routines (p = 0.157). A strong correlation (R = 0.805) was found between 1RM squat and SBJ. These data indicate that warm-up of any type has little effect on jump performance and that maximum strength is strongly related to jumping ability.

Adult↗

PubMed2003

Maximum strength-power-performance relationships in collegiate throwers.

Presently the degree to which peak force influences power production or explosive performance such as strength training movements or throwing (shot-put and weight-throw) is unclear. This study describes the relationships between a measure of maximum strength, isometric peak force (IPF), dynamic peak force (PF), peak power (PP), the 1-repetition movement power snatch (SN), and throwing ability over an 8-week training period. Five male and 6 female (n = 11) well-trained collegiate throwers participated. PF was measured using an AMTI force plate; PP was measured using an infrared-ultrasonic tracking device (V-Scope, Lipman Electronics). Clean pulls from the midthigh position were assessed isometrically and dynamically at a constant load, 30% and 60% of IPF. Specific explosive strength was evaluated using an SN and using the shot-put (SP) and weight-throw (WGT) measured under meet conditions. Variables (PF, PP, SN) were assessed 3 times at 0 weeks, 4 weeks, and 8 weeks. Each measurement period preceded a field meet by 3 days. Peak force, peak rate of force development, and PP increased over the 8 weeks. Correlation coefficients (r) indicate that IPF is strongly related to dynamic PF and PP 30%, 60% of the IPF. Furthermore, strong correlations were found for the SN and the distance for the SP and WGT, and these relationships tended to increase over time. Results suggest that maximum strength (i.e., IPF) is strongly associated with dynamic PF. In addition, maximum strength is strongly associated with PP even at relatively light loads such as those associated with sport-specific dynamic explosiveness (i.e., SN, SP, WGT).

Adolescent↗

PubMed2003

Reliability of power output during short-duration maximal-intensity intermittent cycling.

The aims of the present study were: (a) to determine the number of familiarization trials required to establish a high degree of reliability in measures of power output during maximal intermittent cycling; and (b) to examine the reliability of those same measures after familiarization had been established. On separate days over a 3-week period, 2 groups of 7 recreationally active men completed 8 trials of 1 of 2 maximal (20 x 5-second) intermittent cycling tests with contrasting recovery periods (10-seconds or 30-seconds). Significant (p < 0.05) between-trial differences were detected in post-hoc tests involving trials 1 and 2 only. Within-subject test-retest reliability was therefore assessed across trials 3-8. Apart from values of maximum power output in Protocol 1 (10-second recovery periods), all remaining measures of power output showed high degrees of within-subject test-retest reliability (coefficient of variation: 2.4-3.7%). The results of the present study indicate that in subjects unfamiliar with maximal intermittent cycling, high degrees of reliability in many performance measures can be achieved following the completion of 2 familiarization trials.

Adult↗

PubMed2002

American College of Sports Medicine position stand. Progression models in resistance training for healthy adults.

In order to stimulate further adaptation toward a specific training goal(s), progression in the type of resistance training protocol used is necessary. The optimal characteristics of strength-specific programs include the use of both concentric and eccentric muscle actions and the performance of both single- and multiple-joint exercises. It is also recommended that the strength program sequence exercises to optimize the quality of the exercise intensity (large before small muscle group exercises, multiple-joint exercises before single-joint exercises, and higher intensity before lower intensity exercises). For initial resistances, it is recommended that loads corresponding to 8-12 repetition maximum (RM) be used in novice training. For intermediate to advanced training, it is recommended that individuals use a wider loading range, from 1-12 RM in a periodized fashion, with eventual emphasis on heavy loading (1-6 RM) using at least 3-min rest periods between sets performed at a moderate contraction velocity (1-2 s concentric, 1-2 s eccentric). When training at a specific RM load, it is recommended that 2-10% increase in load be applied when the individual can perform the current workload for one to two repetitions over the desired number. The recommendation for training frequency is 2-3 d x wk(-1) for novice and intermediate training and 4-5 d x wk(-1) for advanced training. Similar program designs are recommended for hypertrophy training with respect to exercise selection and frequency. For loading, it is recommended that loads corresponding to 1-12 RM be used in periodized fashion, with emphasis on the 6-12 RM zone using 1- to 2-min rest periods between sets at a moderate velocity. Higher volume, multiple-set programs are recommended for maximizing hypertrophy. Progression in power training entails two general loading strategies: 1) strength training, and 2) use of light loads (30-60% of 1 RM) performed at a fast contraction velocity with 2-3 min of rest between sets for multiple sets per exercise. It is also recommended that emphasis be placed on multiple-joint exercises, especially those involving the total body. For local muscular endurance training, it is recommended that light to moderate loads (40-60% of 1 RM) be performed for high repetitions (> 15) using short rest periods (< 90 s). In the interpretation of this position stand, as with prior ones, the recommendations should be viewed in context of the individual's target goals, physical capacity, and training status.

Adaptation, Physiological↗

PubMed2002

Snatch technique of collegiate national level weightlifters.

Bar trajectory during weightlifting movements is related to the position of the body during the lift and the displacement of the feet during the drop-under phase. The purpose of this study was to examine anterior-posterior foot displacement and its relationship with performance in the snatch of collegiate weightlifters. Snatch attempts of men weightlifters from the 1998 U.S.A. Weightlifting Collegiate National Championships were analyzed for horizontal displacement of the feet by video analysis. Lifts were analyzed under 2 conditions: all lifts combined and the heaviest successful attempt for each lifter. Lifts (n = 74) were placed into 4 groups: forward displacement (FD, >2.5 cm); no displacement (ND, +/-2.5 cm); rearward displacement (RD, >2.5 cm); and those that showed asymmetric (AS, >7 cm difference in right and left foot) displacement of the feet. Chi-square revealed no significant difference in success rate between groups for all attempts. No statistically significant differences were noted between groups in body mass to bar mass ratio or Sinclair formula for heaviest successful attempts. Results indicate that foot displacement did not significantly affect snatch success or lifting ability in collegiate national level lifters.

Adult↗