Search Results

You are looking at 21 - 28 of 28 items for

  • Author: Robert U. Newton x
  • All content x
Clear All Modify Search
Restricted access

Bradley C. Nindl, William J. Kraemer, Lincoln A. Gotshalk, James O. Marx, Jeff S. Volek, Jill A. Bush, Keijo Häkkinen, Robert U. Newton, and Steve J. Fleck

Regional fat distribution (RFD) has been associated with metabolic derangements in populations with obesity. For example, upper body fat patterning is associated with higher levels of free testosterone (FT) and lower levels of sex-hormone binding globulin (SHBG). We sought to determine the extent to which this relationship was true in a healthy (i.e., non-obese) female population and whether RFD influenced androgen responses to resistance exercise. This study examined the effects of RFD on total testosterone (TT), FT, and SHBG responses to an acute resistance exercise test (ARET) among 47 women (22 ± 3 years; 165 ± 6 cm; 62 ± 8 kg; 25 ± 5 %BF; 23 ± 3 BMI). RFD was characterized by 3 separate indices: waist-to-hip ratio (WHR), ratio of upper arm fat to mid-thigh fat assessed with magnetic resonance imaging (MRI ratio), and ratio of subscapular to triceps ratio (SB/TRi ratio). Skinfolds were measured for the triceps, chest, subscapular, mid-axillary, suprailaic, abdomen, and thigh regions. The ARET consisted of 6 sets of 10 RM squats separated by 2-min rest periods. Blood was obtained pre- and post- ARET. TT, FT, and SHBG concentrations were determined by radioimmunoassay. Subjects were divided into tertiles from the indices of RFD, and statistical analyses were performed by an ANOVA with repeated measures (RFD and exercise as main effects). Significant (p < .05) increases following the AHRET were observed for TT (~25%), FT (~25%), and SHBG (4%). With multiple regression analysis, anthropometric measures significantly predicted pre- concentrations of FT, post-concentrations of TT, and pre-concentrations of SHBG. The SB/TRi and MRI ratios but not the WHR, were discriminant for hormonal concentrations among the tertiles. In young, healthy women, resistance exercise can induce transient increases in testosterone, and anthropometric markers of adiposity correlate with testosterone concentrations.

Restricted access

Tai T. Tran, Lina Lundgren, Josh Secomb, Oliver R.L. Farley, G. Gregory Haff, Laurent B. Seitz, Robert U. Newton, Sophia Nimphius, and Jeremy M. Sheppard

Purpose:

To determine whether a previously validated performance-testing protocol for competitive surfers is able to differentiate between Australian elite junior surfers selected (S) to the national team and those not selected (NS).

Methods:

Thirty-two elite male competitive junior surfers were divided into 2 groups (S = 16, NS = 16). Their age, height, body mass, sum of 7 skinfolds, and lean-body-mass ratio (mean ± SD) were 16.17 ± 1.26 y, 173.40 ± 5.30 cm, 62.35 ± 7.40 kg, 41.74 ± 10.82 mm, 1.54 ± 0.35 for the S athletes and 16.13 ± 1.02 y, 170.56 ± 6.6 cm, 61.46 ± 10.10 kg, 49.25 ± 13.04 mm, 1.31 ± 0.30 for the NS athletes. Power (countermovement jump [CMJ]), strength (isometric midthigh pull), 15-m sprint paddling, and 400-m endurance paddling were measured.

Results:

There were significant (P ≤ .05) differences between the S and NS athletes for relative vertical-jump peak force (P = .01, d = 0.9); CMJ height (P = .01, d = 0.9); time to 5-, 10-, and 15-m sprint paddle; sprint paddle peak velocity (P = .03, d = 0.8; PV); time to 400 m (P = .04, d = 0.7); and endurance paddling velocity (P = .05, d = 0.7).

Conclusions:

All performance variables, particularly CMJ height; time to 5-, 10-, and 15-m sprint paddle; sprint paddle PV; time to 400 m; and endurance paddling velocity, can effectively discriminate between S and NS competitive surfers, and this may be important for athlete profiling and training-program design.

Restricted access

Tai T. Tran, Lina Lundgren, Josh Secomb, Oliver R.L. Farley, G. Gregory Haff, Robert U. Newton, Sophia Nimphius, and Jeremy M. Sheppard

The purpose of this study was to develop and evaluate a drop-and-stick (DS) test method and to assess dynamic postural control in senior elite (SE), junior elite (JE), and junior development (JD) surfers. Nine SE, 22 JE, and 17 JD competitive surfers participated in a single testing session. The athletes completed 5 drop-and-stick trials barefoot from a predetermined box height (0.5 m). The lowest and highest time-to-stabilization (TTS) trials were discarded, and the average of the remaining trials was used for analysis. The SE group demonstrated excellent single-measures repeatability (ICC = .90) for TTS, whereas the JE and JD demonstrated good single-measures repeatability (ICC .82 and .88, respectively). In regard to relative peak landing force (rPLF), SE demonstrated poor single-measures reliability compared with JE and JD groups. Furthermore, TTS for the SE (0.69 ± 0.13 s) group was significantly (P = .04) lower than the JD (0.85 ± 0.25 s). There were no significant (P = .41) differences in the TTS between SE (0.69 ± 0.13 s) and JE (0.75 ± 0.16 s) groups or between the JE and JD groups (P = .09). rPLF for the SE (2.7 ± 0.4 body mass; BM) group was significantly lower than the JE (3.8 ± 1.3 BM) and JD (4.0 ± 1.1 BM), with no significant (P = .63) difference between the JE and JD groups. A possible benchmark approach for practitioners would be to use TTS and rPLF as a qualitative measure of dynamic postural control using a reference scale to discriminate among groups.

Restricted access

Tim L.A. Doyle, Ronald W. Davis, Brendan Humphries, Eric L. Dugan, Bryon G. Horn, Jae Kun Shim, and Robert U. Newton

A number of researchers have long questioned systems used for classifying athletes with disabilities. Wheelchair basketball players have gained much attention from researchers. Despite this, no change to the NWBA classification system has been made since it was first adopted in 1984. This study investigated the NWBA classification system. At two summer basketball camps, 46 players were tested to assess player sprint performance and stratification under the NWBA medical classification system. The group consisted of Class 1, 2, and 3 players. Electronic timing gates were used to collect 20 meter sprint-times. Results indicate that Class 1 players were significantly slower compared to Class 2 and 3 players (p < .05) with no difference between Class 2 and 3. The results of this study support a change to this system.

Restricted access

Lina E. Lundgren, Tai T. Tran, Sophia Nimphius, Ellen Raymond, Josh L. Secomb, Oliver R.L. Farley, Robert U. Newton, Julie R. Steele, and Jeremy M. Sheppard

Purpose:

To develop and evaluate a multifactorial model based on landing performance to estimate injury risk for surfing athletes.

Methods:

Five measures were collected from 78 competitive surfing athletes and used to create a model to serve as a screening tool for landing tasks and potential injury risk. In the second part of the study, the model was evaluated using junior surfing athletes (n = 32) with a longitudinal follow-up of their injuries over 26 wk. Two models were compared based on the collected data, and magnitude-based inferences were applied to determine the likelihood of differences between injured and noninjured groups.

Results:

The study resulted in a model based on 5 measures—ankle-dorsiflexion range of motion, isometric midthigh-pull lower-body strength, time to stabilization during a drop-and-stick (DS) landing, relative peak force during a DS landing, and frontal-plane DS-landing video analysis—for male and female professional surfers and male and female junior surfers. Evaluation of the model showed that a scaled probability score was more likely to detect injuries in junior surfing athletes and reported a correlation of r = .66, P = .001, with a model of equal variable importance. The injured (n = 7) surfers had a lower probability score (0.18 ± 0.16) than the noninjured group (n = 25, 0.36 ± 0.15), with 98% likelihood, Cohen d = 1.04.

Conclusions:

The proposed model seems sensitive and easy to implement and interpret. Further research is recommended to show full validity for potential adaptations for other sports.

Restricted access

William J. Kraemer, N. Travis Triplett, Andrew C. Fry, L. Perry koziris, Jeffrey E. Bauer, James M. Lynch, Tim McConnell, Robert U. Newton, Scott E. Gordon, Richard C. Nelson, and Howard G. Knuttgen

The purpose of this study was to provide an in-depth sports medicine profile of women college tennis players and determine the relationships among an array of performance and clinical variables. Thirty-eight non-resistance-trained women from NCAA Divisions I and III collegiate tennis teams participated. A comprehensive battery of performance tests was conducted on each subject, including measurements of dynamic, isometric, and isokinetic strength; joint laxity and flexibility; speed; agility; power and power endurance; peak oxygen consumption; body composition; and ball velocities of the serve, forehand, and backhand. It was found that no single variable strongly explains tennis performance. The low amount of shared variance of strength measures with ball velocities suggests that tennis skills play a large role in producing peak ball velocities in this group. Due to the large range observed in profiled variables, individual evaluation is needed for clinical and conditioning recommendations.

Restricted access

William J. Kraemer, Jill A. Bush, Robbin B. Wickham, Craig R. Denegar, Ana L. Gomez, Lincoln A. Gotshalk, Noel D. Duncan, Jeff S. Volek, Robert U. Newton, Margot Putukian, and Wayne J. Sebastianelli

Context:

Prior investigations using ice, massage, or exercise have not shown efficacy in relieving delayed-onset muscle soreness.

Objectives:

To determine whether a compression sleeve worn immediately after maximal eccentric exercise enhances recovery.

Design:

Randomized, controlled clinical study.

Setting:

University sports medicine laboratory.

Participants:

Fifteen healthy, non-strength-trained men, matched for physical criteria, randomly placed in a control group or a continuous compression-sleeve group (CS).

Methods and Measures:

Subjects performed 2 sets of 50 arm curls. 1RM elbow flexion at 60°/s, upper-arm circumference, resting-elbow angle, serum creatine kinase (CK), and perception-of-soreness data were collected before exercise and for 3 days.

Results:

CK was significantly (P < .05) elevated from the baseline value in both groups, although the elevation in the CS group was less. CS prevented loss of elbow extension, decreased subjects’ perception of soreness, reduced swelling, and promoted recovery of force production.

Conclusions:

Compression is important in soft-tissue-injury management.

Restricted access

William J. Kraemer, Ana L. Gómez, Nicholas A. Ratamess, Jay R. Hoffman, Jeff S. Volek, Martyn R. Rubin, Timothy P. Scheett, Michael R. McGuigan, Duncan French, Jaci L. VanHeest, Robbin B. Wickham, Brandon Doan, Scott A. Mazzetti, Robert U. Newton, and Carl M. Maresh

Objective:

To determine the effects of Vicoprofen®, ibuprofen, and placebo on anaerobic performance and pain relief after resistance-exercise-induced muscle damage.

De-sign:

Randomized, controlled clinical study.

Setting:

University human-performance/sports-medicine laboratory.

Participants:

36 healthy men.

Methods and Measures:

After baseline testing (72 h), participants performed an eccentric-exercise protocol. Each was evaluated for pain 24 h later and randomly assigned to a Vicoprofen (VIC), ibuprofen (IBU), or placebo (P) group. Postexercise testing was performed every 24 h for 4 d.

Results:

Significantly greater muscle force, power, and total work were observed in VIC than in P (P < .05) for most time points and for IBU at 48 h.

Conclusions:

Anaerobic performance is enhanced with VIC, especially within the first 24 h after significant muscle-tissue damage. The greater performances observed at 48 h might be a result of less damage at this time point with VIC treatment.